radiology for surgeons_in_clinical_practice

Radiology for Surgeonsin Clinical Practice

Evis Sala · Alan H. Freeman ·David J. Lomas · Helmut Ringl

Radiology for Surgeonsin Clinical Practice

Foreword by Johannes Zacherl

123

Evis Sala Alan H. FreemanDepartment of Radiology Department of RadiologyAddenbrooke’s Hospital Addenbrooke’s HospitalCambridge CambridgeUK UK

David J. Lomas Helmut RinglDepartment of Radiology Department of RadiologyAddenbrooke’s Hospital Medical University ViennaCambridge ViennaUK Austria

ISBN: 978-1-84800-095-7 e-ISBN: 978-1-84800-096-4DOI: 10.1007/978-1-84800-096-4

British Library Cataloguing in Publication DataRadiology for surgeons in clinical practice

1. Interventional radiology 2. Diagnosis, SurgicalI. Sala, Evis616′ .0757

ISBN-13: 9781848000957

Library of Congress Control Number: 2007943248

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Foreword

In the daily medical routine, recent refinements of severalmodern imaging techniques enable us to enhance diagnosticaccuracy. Tremendous efforts in radiology have been madeto help us to avoid inappropriate interventions and treat-ments by a misleading diagnosis and to obviate false-negativeresults, too.

The rapid development of imaging techniques requirescontinuing theoretical updating in this field by publica-tions like the current compendium. Theoretical principles ofradiology methods are brought up in a concise manner, andaccording to the composition of modern medical universitycurricula, the pathology findings are arranged and describedin dependence on clinical symptoms rather than as a listing ofdiseases. This configuration therefore turns the opus in frontof you into a useful and valuable companion during surgicaleducation. The initial tentativeness of young trainees and ofthe nonradiology “old hand” in the face of modern imagingtechniques and new contrast agents, will rapidly disappearand turn into enlightened familiarity, helping one to usethose fine arts in discovering the patient’s problem and inthe planning of treatment strategy.

In the era of interdisciplinary boards and discussion,surgeons traditionally are an essential driving force. Thisposition demands an expertise in imaging, which may bestrengthened by a special advantage: the surgeon is in theunique position to immediately compare radiology findingswith the intracorporeal situation during surgery, what weoften might call “the clinical truth.” This circumstance allowsfor an accurate learning effect, which should be a centralaspect of training in clinical decision making. A furtheradvantage of close-to-the-patient disciplines is the correlation

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vi Foreword

between clinical signs and radiology findings. I do not want toend this foreword without emphasizing the need of keepingan eye on the clinical signals and additionally on informationdelivered by modern technology.

My first mentor repeated the claim that “the surgeon isthe better radiologist.” Thanks to the authors of this book,this sentence may again become true.

Johannes Zacherl

Preface

Hamilton Bailey, in his time perhaps the foremost teacher ofsurgery in the English language, described assessment of theacute abdomen in his book, Demonstration of Physical Signsin Clinical Surgery (1960), as follows:

Physical signs and their interpretation reach a high pinnacleof importance in the diagnosis of acute abdominal disease.Frequently an urgent and all important diagnosis has to beformulated by their aid alone.

How times have changed and the perspective from nearlyhalf a century later is completely different.

The history and clinical examination still remain thebedrock of diagnosis but virtually no patient today will passthrough the hands of a surgeon without some form of radio-logical imaging, from the simple plain radiographic image tocomplex 3D reformats of data sets acquired during CT andMR examinations. In this context, diagnostic imaging hasrevolutionized the way surgery is practiced. It thus behoovesthe surgical trainee to remain abreast of all the techniquesavailable and to be cognizant of their advantages and disad-vantages.

In this small book, the authors – all radiologists –have attempted to look at the patient from the clinicalperspective of symptoms and signs, and then to formulatethe relevant imaging which would be appropriate for theirmanagement.

Our intention has been to produce a radiological guidefor the surgical trainee, without delving too deeply into thetechnological processes of image acquisition and manipu-lation. We hope it helps.

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viii Preface

Our particular thanks go to Melissa Morton of SpringerUK for the encouragement to produce this book and toBarbara Chernow and all the production team at Springerwho have been responsible for bringing it to fruition.

Evis SalaAlan H. Freeman

David J. LomasHelmut Ringl

Contents

Foreword by Johannes Zacherl........................................... vPreface .................................................................................... vii

Part I Principles of Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1. Plain Radiographs, or X-rays ..................................... 11.2. Contrast Medium Studies ........................................... 3

1.2.1. Oral Contrast Medium Studies ...................... 31.2.2. Intravenous Contrast Medium Studies ......... 4

1.2.2.1. Intravenous Urography.................... 51.2.2.2. X-ray Angiography........................... 6

1.3. Cross-sectional Imaging .............................................. 71.3.1. Ultrasound ........................................................ 71.3.2. Computed Tomography.................................. 81.3.3. Magnetic Resonance Imaging ........................ 10

1.4. Nuclear Medicine Imaging.......................................... 12

Part II Imaging of Common Clinical Problems . . . . . . . 15

2.1. Pain and the Acute Abdomen ................................... 152.1.1. Chest Pain ......................................................... 16

2.1.1.1. Pneumothorax ................................... 162.1.1.2. Aortic Dissection .............................. 182.1.1.3. Infections............................................ 212.1.1.4. Tumors ............................................... 242.1.1.5. Boerhaave’s Syndrome .................... 27

2.1.2. Abdominal Pain ............................................... 302.1.2.1. Small Bowel Obstruction................. 332.1.2.2. Large Bowel Obstruction ................ 342.1.2.3. Pseudoobstruction ............................ 38

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x Contents

2.1.2.4. Perforation of Hollow Viscus ......... 382.1.2.5. Acute Appendicitis........................... 422.1.2.6. Acute Cholecystitis........................... 472.1.2.7. Acute Pancreatitis............................. 502.1.2.8. Small Bowel Ischemia ...................... 532.1.2.9. Renal Colic ........................................ 56

2.1.3. Abdominal Sepsis ............................................ 602.1.3.1. Intraabdominal Collections ............. 602.1.3.2. Imaging of Postoperative

Abdomen............................................ 642.2. Mass ............................................................................... 66

2.2.1. Imaging of Abdominal Masses by TheirLocation............................................................. 662.2.1.1. Liver Tumors..................................... 662.2.1.2. Adrenal Tumors................................ 712.2.1.3. Tumors of the Pancreas ................... 752.2.1.4. Retroperitoneal Sarcoma................. 77

2.2.2. Abdominal Aortic Aneurysm ........................ 782.3. Bleeding......................................................................... 82

2.3.1. Gastrointestinal Bleeding ............................... 822.3.1.1. Diagnosis of Upper

Gastrointestinal Bleeding ................ 832.3.1.1.1. Endoscopy ....................... 832.3.1.1.2. Angiography.................... 842.3.1.1.3. Nuclear Medicine

Studies .............................. 842.3.1.2. Causes of Upper

Gastrointestinal Bleeding ................ 842.3.1.2.1. Esophagitis, Ulcers,

and Varices ...................... 842.3.1.2.2. Gastric Erosions and

Peptic Ulceration ............ 862.3.1.2.3. Tumors of

the UpperGastrointestinal Tract..... 88

2.3.1.3. Diagnosis of LowerGastrointestinal Bleeding ................ 922.3.1.3.1. Nuclear Medicine

Studies .............................. 92

Contents xi

2.3.1.3.2. Angiography.................... 922.3.1.3.3. Colonoscopy .................... 932.3.1.3.4. Capsule Endoscopy ........ 93

2.3.1.4. Causes of LowerGastrointestinal Bleeding ................ 932.3.1.4.1. Diverticular Disease....... 932.3.1.4.2. Colorectal Carcinoma .... 972.3.1.4.3. Inflammatory Bowel

Disease.............................. 992.3.1.4.4. Meckel’s Diverticulum... 1042.3.1.4.5. Angiodysplasia ................ 104

2.3.2. Hematuria ......................................................... 1062.4. Jaundice ......................................................................... 110

2.4.1. Radiologic Evaluation of MechanicalBiliary Obstruction........................................... 1102.4.1.1. Biliary Stones .................................... 1122.4.1.2. Carcinoma of the Head of the

Pancreas.............................................. 1142.4.1.3. Tumors of the Biliary Tract ............ 115

2.5. Trauma........................................................................... 1182.5.1. Chest Trauma ................................................... 1182.5.2. Abdominal Trauma ......................................... 123

2.5.2.1. Hepatic Trauma ................................ 1252.5.2.2. Pancreatic Trauma............................ 1262.5.2.3. Splenic Trauma ................................. 1262.5.2.4. Renal Tract Trauma......................... 1272.5.2.5. Bladder Trauma................................ 129

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Part IPrinciples of Imaging

Imaging investigations are an essential part of the managementof patients presenting with surgical problems. To have alogical plan of investigation for a particular clinical situation,an understanding of the imaging techniques is requiredincluding the method of generating an image, costs, strengths,weaknesses, and associated risks. This chapter introducesthe basic concepts of the available imaging modalitiesand their advantages and disadvantages in clinical practice.

1.1 Plain Radiographs, or X-rays

X-rays are electromagnetic radiation with an energy andfrequency substantially greater than visible light. They aregenerated within an X-ray tube, in which electrons are accel-erated at a small metal target from which X-rays are thenemitted. These are then collimated into a shaped beam anddirected at the relevant part of a patient. Depending uponthe intervening tissue’s attenuation properties, a character-istic pattern of X-rays is transmitted through the imaged part.Conventionally, these X-rays are then converted by phosphorscreens into light photons, which expose photographic filmsubsequently processed to create the X-ray film or radio-graph viewed on a lightbox. Increasingly, these systems arebeing replaced by solid-state X-ray detectors (e.g., selenium-based or amorphous silicon–based materials), which convertX-rays indirectly (computed radiography; CR) or directly(direct radiography; DR) into electrical signals, providing

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2 Part I. Principles of Imaging

digital and filmless acquisition. These are usually reviewedon workstations but can be converted to film if needed.Image contrast relies on the fact that different parts of thebody attenuate (stop) X-rays better than others. Lungs aremostly gas, and most X-rays pass straight through, whereasbones are high in calcium, which absorbs X-rays to a highdegree. A tissue structure is often only visible if it liesadjacent to another tissue of different density. In generalterms, the major attenuation differences occur between gas,soft tissues, fat, and bone. Therefore, radiographic examina-tions are particularly good for directly imaging bony struc-tures and those containing gas, such as the lungs. Conven-tional radiographs are projection techniques providing nointrinsic depth information, therefore interpreting abdominaland pelvic examinations requires some skill, for example tounderstand the patterns of normal and abnormal gas andfluid distribution.

An additional feature of X-rays is that they may be used toobtain dynamic information using an image intensifier. This istermed fluoroscopy and allows real-time observation duringa range of diagnostic and therapeutic procedures. Despitenewer, more sophisticated forms of imaging, a plain radio-graph remains one of the cheapest, fastest, and simplest waysof detecting many problems; however, they lack sensitivityand specificity. The diagnostic advantage of the use of X-rays typically outweighs the risks from the effects of ionizingradiation (see Section 1.3.2).

Advantages Disadvantages

• Fast • Uses ionizing radiation• Relatively inexpensive • Limited soft tissue

contrast• High spatial resolution • Projection method• Widely available lacking any true depth

discrimination

1.2 Contrast Medium Studies 3

1.2 Contrast Medium Studies

A limitation of plain X-ray examination is that most ofthe soft tissue structures of the body are of similar radio-graphic density. To visualize these various soft tissue struc-tures, contrast agents were developed and improved duringthe 20th century. Although negative contrast using gas waswidely used, most studies now employ positive contrastmedia that attenuate X-rays by means of their high atomicnumber. These agents include barium sulfate used mainly inthe gastrointestinal tract and water-soluble agents containingbound iodine that may also be used intravenously.

1.2.1 Oral Contrast Medium Studies

Barium sulfate is an inert, insoluble substance that can betaken orally and used to outline the various portions of thegastrointestinal tract. Improved results and higher sensitivityare achieved with double-contrast studies combining both gasdistension and barium coating of the luminal surface of theorgan being examined.

An important issue is the choice of contrast media in caseof suspected esophageal tear or gastrointestinal perforation.Barium in the mediastinal or peritoneal cavity is harmful andmay cause mediastinal or peritoneal fibrosis. Water-solublenon-ionic contrast media are safer, although they lack thelevel of anatomic definition created by barium. Similarly,if aspiration is suspected or likely, water-soluble, non-ioniccontrast media should always be used first, followed bybarium if there is no obvious leak. Ionic, water-solublecontrast media such as Gastrografin (Schering Health CareLtd., Burgess Hill, West Sussex, UK) should be avoided asthey cause severe pulmonary edema if aspirated.Examples of barium studies are as follows:

Barium swallow: This is used for the imaging of the pharynxand the esophagus. It is one of the first-line investigationmethods for esophageal disorders, particularly in casesof dysphagia. Good fluoroscopy is important, and video


recordings are made as the barium is swallowed if a motilitydisorder is suspected.

Barium meal: Used for examination of the lower esophagus,stomach, and duodenum. Double-contrast techniquesprovide excellent detail of the mucosal surface of thestomach and duodenum. Although considered the basictechnique for radiologic investigation of the stomach, ithas been largely replaced by endoscopy.

Small bowel study: Used to examine the structure andmotility of the small bowel. Barium can be given eitherorally (barium follow-through) or administered via a tubeplaced into the distal duodenum or proximal jejunum(small bowel enema or enteroclysis). Barium introduceddirectly into the small bowel offers exquisite visualizationby creating an uninterrupted column of contrast mediumdistending the jejunum and ileum. This facilitates detectionof any structural abnormality that might be present.Capsule endoscopy has replaced this technique for subtlelesions with no morphologic changes (e.g., some arterio-vascular malformations).

Barium enema: Double contrast using barium and air via arectal tube to outline the lumen and mucosa of the largebowel. Despite the increasing role of colonoscopy, double-contrast barium enema remains widely used for exami-nation of the large bowel. Limited single-contrast studiescan be used to demonstrate and confirm the level of acolonic obstruction or a fistula.

1.2.2 Intravenous Contrast Medium Studies

Intravenous contrast medium is used to enhance vessel andtissue contrast in various X-ray–dependent imaging modal-ities. After intravenous administration, the contrast agentpasses through the venous and arterial system, thus renderingthese vessels visible. During circulation, a certain amountof the contrast medium passes through the vessel walland distributes to the extracellular fluid of the surrounding

1.2 Contrast Medium Studies 5

tissue/organs producing the necessary contrast to showanatomic and pathologic details. The contrast medium isthen excreted through the kidneys and finally delineates theurinary tract.

Intravenous contrast media that are used for X-ray exami-nations are based on iodine. They can be categorized asionic and non-ionic, depending on their molecular structureand osmotic behavior in the blood. Non-ionic contrastmedia such as Iopamidol (Bracco UK Ltd., Wooburn Green,Buckinghamshire, UK) have less risk of adverse reactions(in part related to their low osmolarity) but are typicallymore expensive than their ionic equivalents. Side effectsinclude nephrotoxicity and allergic reactions ranging frommild skin alterations to anaphylaxis. Therefore, elevatedserum creatinine levels and a previous history of contrastmedium allergy represent relative contraindications, and analternative imaging modality such as ultrasound (US) ormagnetic resonance imaging (MRI) should be considered. Ifthe use of an iodine-based contrast medium is unavoidable,high-risk patients should receive a premedication with corti-costeroids (prednisolone 30 mg orally 12 and 2 hours beforecontrast medium) and antihistamines. To reduce nephrotox-icity, all patients should be adequately hydrated before thecontrast medium injection, and intravenous fluids may beneeded for those with known renal impairment.

1.2.2.1 Intravenous Urography

Intravenous urography (IVU) is used to investigate urinarytract disorders, especially renal colic. It provides someanatomic and functional renal information but is most usefulfor demonstrating the ureters and pelvicaliceal systems 5 to20 minutes after injection of intravenous contrast medium.An initial plain radiograph (to look for renal tract calcifi-cation) is always obtained. In the case of acute renal colic,IVU has been partially replaced by low-dose unenhancedcomputed tomography (CT) in many institutions. The latteryields not only higher sensitivity and specificity but offersalso additional information of all other abdominal organs.


1.2.2.2 X-ray Angiography

Arteriography demonstrates narrowing or obstruction (byplaque, thrombus, or embolus) of major organ arteries suchas the coronary, cerebral, or carotid. It is achieved byinjection of contrast medium directly into the artery viaa catheter. This relatively invasive technique also allowstherapeutic interventions such as dilating narrowed arteries(angioplasty) or blocking off leaking or ruptured vessels(embolization). The development of less invasive techniquessuch as Doppler ultrasound, computed tomography angiog-raphy (CTA), and magnetic resonance angiography (MRA)has replaced the majority of diagnostic angiography.

The most common approach for both diagnostic and thera-peutic angiography is via direct puncture of the commonfemoral artery. Other approaches can be used when thefemoral approach is impossible because of occlusive iliacdisease. Different catheter sizes and shapes are used forparticular procedures such as selective arteriography of celiacaxis and mesenteric and renal arteries. These techniques areinvasive with small but definite associated risks includingaccidental rupture or blockage of a vessel, which mayoccasionally lead to serious morbidity or mortality.

Digital subtraction angiography takes advantage of digitaldata acquisition, storage, and processing. First, an image istaken without contrast medium in the vessel: the mask. Thenimages are taken as contrast medium is being injected: thecontrast film. Finally, the computer subtracts the mask fromthe contrast film leaving an image of the vessels withoutthe background bone. This technique offers superior contrastresolution with lower doses of contrast medium, though thespatial resolution is inferior to conventional angiography. Itplays an important role in interventional studies as the imagescan be viewed immediately.

In venography, contrast medium is injected via a needle orcatheter positioned directly into the vein to be imaged, andseries of plain radiographs/digital images are taken. The roleof venography in occlusive disease of the leg veins has beenlargely superseded by compression ultrasound.

1.3 Cross-sectional Imaging 7

1.3 Cross-sectional Imaging

1.3.1 Ultrasound

US provides real-time cross-sectional imaging of soft tissues.Because of its ability to differentiate tissue characteristicsand demonstrate blood flow, US has become a valuabletechnique for evaluating solid organs and vessels as well asan excellent method of guiding interventional procedures.US is a relatively inexpensive, rapid imaging modality thatavoids ionizing radiation. It is patient friendly, as it oftenrequires no special preparation. Mobile US machines can betaken to the bedside or into the operating theater, providinga great advantage for emergency use. US can also be usedto guide tissue biopsy or drainage procedures because of theinteractive nature of real-time US.

US uses high-frequency sound waves produced by piezo-electric crystals that transform electrical energy into longi-tudinal compression waves (2 to 20 MHz); these echoes arereflectedechoes inasimilar fashiontosonarandradar.Modernsystems use pulses of US and by timing the delay for theechoes to return calculate the depth at which the reflected echooriginated. Sophisticated computing, crystal multiplexing,and signal processing allows for real-time image display.

Image contrast is generated by tissues that have varyingacoustic impedance, and at cellular and tissue interfaces,impedance mismatches result in varying amounts of echoreflection. The terms increased or decreased echoreflectivityare used to describe tissues appearing bright or dark, respec-tively. Pure fluid reflects no sound and is often termedanechoic, typically appearing black on an image.

A major limitation of ultrasound imaging is the inabilityto see through gas and bone, limiting particularly the exami-nation of the iliac fossae and retroperitoneum. Endolu-minal transducers can also be used to avoid problemswith obscuring gas and to improve resolution; for example,transvaginal, transrectal, endoscopic, intraductal (biliary andpancreatic), and intravascular transducers have all beendeveloped.


Doppler US is based on the Doppler effect. When theobject reflecting US waves is moving, it shifts the frequencyof the returning echoes, creating a higher frequency if itis moving toward the probe and a lower frequency if it ismoving away from the probe. The frequency shift is directlyrelated to the object’s velocity allowing a real-time display ofestimated blood velocity, which can be useful in large vesselsto estimate stenoses (e.g., for the carotid and cardiac valves).This information can be graphed against time (duplex US andM-mode) or used to provide a color overlay on a real-timeimage (color Doppler imaging).

Contrast agents have recently been developed using small“microbubbles” able to pass through the capillary bed andprovide increased echoreflectivity. Clinical applications beingevaluated include fallopian tube patency, detection of vesico-ureteric reflux, assessment of portal venous patency incirrhosis, diagnosis of renal artery stenosis, and so forth.Recently, liver specific microbubbles have been developed toincrease sensitivity in the detection of focal liver malignancies.

US is considered a very safe technique, and is widely usedin pediatrics and obstetrics. There are theoretical concernsrelated to tissue heating and cavitation within cells that limitthe power used, particularly using endovaginal probes inearly pregnancy.


• Cheap • Cannot see through gas or bone• Portable • Limited window and filmed record• Safe • More operator dependent than CT

1.3.2 Computed Tomography

CT uses X-rays to obtain cross-sectional images that providedepth information. Modern systems can rapidly and robustlyimage a combination of soft tissue, bone, and blood vessels.


The use of a calibrated X-ray detector system providesmuch improved soft tissue contrast compared with conven-tional radiographs although the mechanism of image contrastremains the same. CT is increasingly used in both acuteand chronically ill patients and is also essential to guidepercutaneous interventional procedures such as biopsies anddrainage of fluid collections.

Current CT systems use continuous spiral data acquisitionin the axial plane as the patient moves through a rotatingfan-beam of X-rays. A volume of data is acquired that maybe reformatted in other anatomic planes as required. Intra-venous contrast medium allows for vascular imaging andalso improved organ imaging with the detection of patho-logic lesions as based on their vascular enhancement. Owingto the short total acquisition time of spiral CT, differentcontrast enhancement phases are now possible. These multi-phase studies can further improve the characterization offocal lesions. Multislice spiral CT scanners can simultane-ously collect up to 64 or more slices of data during each spiralrotation reducing examination times and allowing improvedimage reformatting.

CT is particularly sensitive for detecting acute hemor-rhage, gas, and calcium and for these reasons is widelyused in the evaluation of acute trauma. Other recent appli-cations of CT include use as a first-line investigation inthe diagnosis of abdominal pain, appendicitis, and renalcolic. CT examination is fast and simple, enabling a quickoverview of possible life-threatening pathology, and facili-tates a dedicated surgical treatment.

As a result of all these new applications and improvements,there has been a dramatic increase in the number of CT exami-nations, which now account for the majority of medical irradi-ation of the population. As a result of this ionizing radiation,there is an estimated increased lifetime risk of 1 in 2500 solidmalignancies from the dose of a single routine abdomen-pelvicCT. Therefore, it is important that the use of CT is managedappropriately by clinicians and radiologists to ensure that CTis the appropriate investigation in a given clinical situationrather than other “safer” techniques such as US or MRI.


1.3.3 Magnetic Resonance Imaging

MRI provides multiplanar imaging of the body with excellentsoft tissue discrimination and a range of contrast mechanisms.Historically, relatively long imaging times made magneticresonance (MR) less robust for imaging the abdomenand pelvis although new fast-imaging techniques are nowavailable. It has the particular advantage of avoiding the useof ionizing radiation.

MRI exploits the ability of nuclei with an uneven numberof nuclei to resonate (at specific frequencies) between energystates in a magnetic field. As approximately 70% of thehuman body is composed of water and fat, protons are theprimary nucleus used for imaging. When placed in a strongmagnetic field, the protons resonate at a particular frequencyand reach equilibrium. This equilibrium can be disturbed by aradiofrequency-pulse excitation and the return to equilibriumobserved and used to generate images. T1 and T2 relaxationtimes are decay constants reflecting the ability of nuclei toreturn to equilibrium after excitation. Different tissues havevarying T1 and T2 properties that allow them to be discrim-inated in an image. The spatial localization of the tissueswithin the image is complicated and relies on the mathe-matical Fourier transform and additional transiently appliedmagnetic fields.

Soft tissue contrast is superior to X-ray–based CT imagingand readily allows separation of liver, spleen, muscle, fat,tendons, cartilage, and blood flow; however, the ability todiscriminate between calcium, air, and dense fibrous tissueis limited, as these materials all lack protons and thereforegenerate no signal. MR can generate angiograms (MRA)utilizing both intrinsic flow and intravenous bolus injectionsof contrast medium (relying on T1 shortening for the vascularsignal). In addition, heavily T2-weighted (T2W) images usingintrinsic fluids (that have a long T2 value) as contrast havebeen used to noninvasively demonstrate the biliary tree,avoiding the need for invasive endoscopic retrograde cholan-giopancreatography (ERCP) examinations.


MRI has quickly evolved in recent years to becomethe primary diagnostic imaging technique for many neuro-logic and musculoskeletal problems. It is used selectively inabdomen and pelvis, for example in staging pelvic malig-nancy, mapping perineal fistulae, and detecting common bileduct stones. It plays an important role in preoperative stagingof tumors of the rectum, prostate, ovary, and uterus. MRAis replacing many conventional diagnostic angiographicprocedures, for example in the diagnosis of renal arterystenosis and the preoperative evaluation of kidney transplantdonors.

MR contrast agents are based around gadolinium chelates,which are administered intravenously and operate in asimilar fashion to the iodinated agents used in CT. Theyare not organ or pathology specific but may be valuablein distinguishing tumor recurrence from changes due toprevious surgery. Recently, gadolinium-based contrast mediahave been associated with a serious and rare systemicfibrosing condition. The condition appears to be limited topatients with preexisting severe renal impairment, and insuch patients caution should be exercised when using theseagents. Blood-pool and liver-specific contrast agents havebeen developed that allow more prolonged investigation timeand increase the conspicuity of liver lesions. There is ongoingresearch in the development of tumor-specific and targetedagents such as necrosis-specific and inflammation-specificagents. Although not commonly used in clinical practice,several studies have proved MR useful in assisting interven-tional procedures such as biopsy guidance and to monitorradiofrequency, cryoablation, and laser therapies.

MRI is a relatively safe technique although the use of astrong magnetic field may damage pacemakers and causemetal fragments in the retina or brain to move, so patientsare routinely screened for these and other risks. Surgical clipsand joint replacements are, however, not usually a risk to thepatient although they may degrade the images. MRI is alsorelatively motion sensitive leading to image artifacts. This isone reason why MRI has been less robust for imaging acutelyill patients when compared with CT.



• Excellent soft tissue • Complex to understandcontrast and interpret

• Multiplanar acquisition • Motion sensitive

1.4 Nuclear Medicine Imaging

Nuclear medicine (NM) provides primarily functional ratherthan anatomic imaging and relies on detecting emittedgamma rays from radiopharmaceuticals administered topatients. This functional information allows NM techniquesto diagnose certain diseases earlier than other techniques thatprovide mainly anatomic information. For example, boneinfection results in increased cellular activity of bone, causingradionuclides to be taken up in greater amounts by infectedbone. NM techniques may demonstrate this change earlierthan the anatomic image provided by a plain radiograph orCT examination. The amount of radiation that is taken upand then emitted by a specific body part is linked to themetabolic activity and cellular function of the organ or tissue.

NM studies are typically performed using radiationdetectors or gamma cameras after the oral or intravenousintroduction of radioactive chemicals (radionuclides, radio-pharmaceuticals, or radiotracers that emit gamma rays) intothe body. Radiopharmaceuticals are usually formulated tolocalize in the specific part of the body to be studied.The radionuclide substances used in NM imaging are eithersynthesized radioactive substances, such as technetium, orradioactive forms of elements that are naturally found in thebody, such as iodine. The emitted gamma rays are detectedby the gamma camera using a large crystal detector andare spatially localized. The gamma rays are then convertedinto light and subsequent electrical signal, which is used tocreate the image. As the method relies on the emission ofgamma rays, the achievable spatial resolution is relatively

1.4 Nuclear Medicine Imaging 13

low compared with other techniques, but this is compensatedfor by the additional functional information.

Emission computed tomography (ECT) is a method ofobtaining three-dimensional localization of the radionuclidewithin the patient. ECT involves cross-sectional data acqui-sition and reconstruction similar to CT. It can be achieved bysingle positron emission computed tomography (SPECT) andpositron emission tomography (PET). SPECT is based on thedetection of single gamma rays emitted from radionuclidessuch as technetium-99m and thalium-201. SPECT imagesrepresent uptake measured from different angular viewsaround the patient so they can be reconstructed in differentanatomic planes. PET involves coincident detection of pairedhigh-energy photons emitted simultaneously after the annihi-lation of positron-emitting radionuclides such as carbon-11, fluorine-18, and so forth. PET is becoming increasinglyimportant in oncology, being able to differentiate in certainsituations between active tumor growth and necrotic tissue.PET is more sensitive than SPECT, but PET scanners aremuch more costly than SPECT scanners and are often onlyavailable in the largest medical centers.


• Provides functional • Poor anatomicinformation definition

• Detection of • Not readily available inradiographically occult emergency situationsabnormalities

To overcome the low spatial resolution and the lackof anatomic detail, PET-CT was recently introduced. Itcombines the anatomic information of CT and the metabolicinformation provided by PET. This ability to demonstrateabnormal metabolic activity enables PET-CT to differentiatebenign from malign tissue (e.g., a scar from a neoplasm).


Suggestions for Further Reading

1. Harvey CJ, Pilcher JM, Eckersley RJ, Blomley MJK, CosgroveDO. Advances in ultrasound. Clin Radiol 2002;57:157–177.

2. Klingenbeck–Regn K, Schaller S, Flohr T, Ohnesorge B,Kopp A, Baum U. Subsecond multi-slice computed tomog-raphy: basics and applications. Eur J Radiol 1999;31:110–124.

3. Terrier F, Grossholz M, Becker CD (eds). Spiral CT of theabdomen. Springer, Berlin, 2002.

4. McRobbie DW, Moore E, Graves MJ, Prince MR. MRI frompicture to proton. Cambridge University Press, Cambridge, UK,2003.

5. Murray IPC, Ell PJ (eds). Nuclear medicine in clinical diagnosisand treatment. Churchill Livingstone, Edinburgh, 1994.

6. Hart B, Wall BF. Radiation exposure of the UK populationfrom the medical and dental x-ray examinations. NRPB, March2002. NRPB. Document W4 pp 1–41. National RadiationProtection Board Health Protection Agency. Chilton; Didcot,Oxford, UK.

7. Thomsen HS, Morcos SK, ESUR. ESUR guidelines on contrastmedia. Abdom Imaging 2006;31(2):131–140.

8. Heneghan JP, McGuire KA, Leder RA, DeLong DM,Yoshizumi T, Nelson RC. Helical CT for nephrolithiasisand ureterolithiasis: comparison of conventional and reducedradiation-dose techniques. Radiology 2003;229(2):575–580.

9. Kapoor V, McCook BM, Torok FS. An introduction to PET-CTimaging. Radiographics 2004;24(2):523–543.

Part IIImaging of Common ClinicalProblems

As has been seen, radiology plays an increasingly importantrole in the management of the surgical patient, bothfor preoperative diagnosis and postoperative management.Techniques have evolved rapidly since the discovery ofX-rays in 1895, and the availability and combination ofdifferent imaging modalities have improved the ability toachieve rapid and accurate diagnoses. Image guidance allowsthe use of percutaneous procedures, such as tumor biopsyand abscess drainage, which avoid the need for open surgery.Radiographic studies remain the first-line imaging techniquein many clinical situations although cross-sectional imagingwith ultrasound (US), magnetic resonance imaging (MRI),and especially computed tomography (CT) are now widelyused in patients with acute abdominal pain and after trauma.The aim of this chapter is to provide a simple diagnosticframework for common surgical situations.

2.1 Pain and the Acute Abdomen

Most diseases of thoracic and abdominal viscera areassociated with pain at some time during their course. Thissection focuses on imaging of certain common clinical situa-tions where pain is a prominent symptom.

15

16 Part II. Imaging of Common Clinical Problems

2.1.1 Chest Pain

It is important for the surgeon to recognize certain imagingfeatures of pathologies resulting in chest pain although physi-cians rather than surgeons will most commonly deal withnontraumatic chest pain.

2.1.1.1 Pneumothorax

Pneumothorax reflects the accumulation of air in the pleuralspace and commonly presents with pleuritic chest painand/or dyspnea. Diagnosis of pneumothorax is made with achest radiograph, which may also demonstrate complicationsand relevant underlying lung pathology. Signs indicating apneumothorax on an erect chest radiograph include:

• Visceral pleural line separated from the chest wall by atransradiant area devoid of blood vessels

• Deep costophrenic sulcus laterally• Visible anterior costophrenic recess (double-diaphragm

sign)• Increased transradiancy of ipsilateral lung or hypochon-

drium• Ipsilateral depression of the diaphragm• Contralateral mediastinal shift

The last two signs in combination and particularlymediastinal shift indicate a tension pneumothorax thattypically causes rapid deterioration in a patient’s clinicalcondition and requires prompt intervention. In situationswhen an erect inspiratory chest radiograph is indeterminate,an expiratory or lateral decubitus radiograph may helpin making the diagnosis. Occasionally, it is difficult todifferentiate pneumothorax from other pulmonary lesions

�Figure 2.1.1.1A,B. Pneumothorax. (A) In this erect chest radio-graph (CXR), the visceral pleural line (arrow) is separated fromthe chest wall by a transradiant area lacking in vascular markingsindicating a right pneumothorax. (B) Left-sided pneumothorax(arrows) causing mild mediastinal shift to the right.


or overlying transradiancies such as simple cysts, emphy-sematous bullae, pneumatoceles, pneumomediastinum, andsurgical emphysema. CT can confidently make the diagnosisof pneumothorax in these cases if required.

2.1.1.2 Aortic Dissection

Aortic dissection is a separation or splitting of the arterialwall and characteristically presents with sudden-onset, severechest pain in the precordial and substernal region radiatingthrough to the back. There are two types of dissectionaccording to the Stanford anatomic classification: type A,which starts in the ascending aorta and proximal arch;and type B, which begins distal to the origin of the leftsubclavian artery. Type A accounts for 70% of aortic dissec-tions and has a high incidence of complications including

Figure 2.1.1.2A. Aortic dissection. Erect posteroanterior (PA)CXR showing widening of superior mediastinum and displacementof the trachea in a 21-year-old man after trauma.

Figure 2.1.1.2B,C. Aortic dissection. (B) Contrast-enhancedCT (CECT) image showing the presence of the intimal flap(arrow) separating the true and false lumen. Note also trachealdisplacement. (C) Axial CECT image of the descending aorta,the true lumen (arrow) is usually smaller and shows an earlierenhancement then the false lumen (arrowhead).


cardiac tamponade, coronary artery occlusion, acute aorticregurgitation, and dissection extension into the major aorticarch branches. Early imaging and diagnosis is essential asthe treatment for type A is usually emergency surgery,whereas type B dissections have a more benign course andare managed conservatively.

Although a normal chest radiograph does not exclude thediagnosis of dissection, this should be performed initially.Suggestive signs of aortic dissection are

• Widening of the mediastinum (on an erect film takenposteroanteriorly)

• Separation of the aortic wall calcification from the marginof the aortic outline by more than 1 cm

• Depression of the left main bronchus• Widening of the paravertebral line

If previous chest radiographs are available, comparison canbe very helpful to assess any recent change in the appearanceof the aortic outline and mediastinum in general.

Depending on the patients’ clinical status, the availabilityof imaging techniques, and local expertise, different imagingroutes can be followed. If the patient is relatively stableand cardiac MRI is immediately available, it is an excellentdiagnostic method. MRI offers multiplanar imaging of theentire aorta with its branches as well as excellent viewsof the mediastinum. Subtle signs such as early intramuralhematoma are particularly well demonstrated. It is usuallyeasy to diagnose full aortic dissection with the intimal flapand the different signal intensity of blood flow in true andfalse lumens. The most important issue is to define the fullextent of the dissection into the aortic branches as wellas complications such as aortic regurgitation, which is wellobserved using cine sequences.

Currently, CT is more widely available than cardiac MRI,and multislice CT offers image reconstruction in differentanatomic planes. It also has the advantage of showing calcifi-cation, which is of value in detecting intimal displacement. Itis important to perform an unenhanced CT acquisition before

2.1 Pain and the Acute Abdomen 21

administering intravenous contrast medium as acute intra-mural hematoma may appear as an ellipse of increased atten-uation. Dynamic intravenous contrast medium–enhanced CTmay show:

• Presence of the intimal flap• Presence of the true and false lumen• Extent of the dissection (aortic branches involved and

possible infarction of intraabdominal viscera)• Complications such as aortic rupture, pericardial collec-

tions, and so forth.

Aortic Dissection

• Chest radiograph is normal in 25%.• MRI is an excellent imaging technique where

available; only for stable patients.• CT is more widely available and is better in showing

intimal calcification.• Aortography has a limited role where CT and/or

MRI are available.

Transthoracic and transesophageal echocardiography havea very high sensitivity and specificity in diagnosis of aorticdissection but are more operator dependent and not alwaysavailable in emergency situations. Invasive aortography,formerly the routine technique for aortic dissection, is nowrarely required.

2.1.1.3 Infections

Lower respiratory tract infection (pneumonia) may presentwith chest pain and is usually diagnosed with chest radio-graphy alone. This evaluates the extent of pneumoniaand its complications, assesses response to treatment, and

Figure 2.1.1.3A. Left lower lobe pneumonia. CXR showing a retro-cardiac opacity which is obscuring the medial aspect of the lefthemidiaphragm.

�Figure 2.1.1.3B,C. Left lower lobe pneumonia. (B) CXR showingright upper lobe pneumonia. (C) Coronal reformatted image ofa CECT of the thorax in the same patient highlighting an airbronchogram (arrow).


demonstrates possible predisposing lung pathologies.Features of pneumonia on a plain chest radiograph include:

• Area of parenchymal opacification, which may be lobar,segmental, or nonsegmental.

• Presence of an air-bronchogram.• Localized translucencies indicating the presence of an

abscess, pneumatocele formation, and so forth.• Volume changes are not usually present unless there is

associated collapse.• Pleural effusion or empyema.• Hydropneumothorax.• Underlying diseases such as malignancy, bronchiectasis,

pulmonary sequestration, bronchogenic cyst, and so forth,which are predisposing factors in developing pneumonia.

Comparison with previous radiographs is helpful for evalu-ating new changes in patients with a predisposing conditionand assessing response to treatment.

2.1.1.4 Tumors

Chest pain may be the presenting symptom in patientswith bronchial carcinoma. Pain often indicates invasion ofthe chest wall by the tumor and carries a poor prognosis.The diagnosis can be suggested from the plain chest radio-graph, although further imaging with CT combined withbronchoscopy and biopsy is usually required for tumorstaging.Radiologic features of bronchial carcinoma include:

• Lung mass with lobular, spherical, or oval shape especiallyif located in the periphery, which may contain cavitationor small areas of calcification.

• Fine streaks of opacity radiating into the lung from acentral mass (corona radiata) or a solitary band (tail)between the lesion and the pleura.

• Lung apex mass (superior sulcus tumor), which mayresemble pleural thickening.

Figure 2.1.1.4A,B. Bronchial carcinoma. (A) CXR showing aspiculated central mass superior to the right hilum. (B) CECTshowing the right central mass as well as small-volume mediastinallymphadenopathy. (Continued)


Figure 2.1.1.4C. (Continued) Bronchial carcinoma. Coronal refor-mation of this tumor using lung window setting.

• Lobar collapse in association with central tumors—adjacent fissures may show a bulge related to the proximalmass.

• The presence of consolidation in an elderly patientconfined to one lobe or more that does not improve over3 weeks despite antibiotic treatment, or recurrent consoli-dation in the same lobe.

• Visible mass with associated compression of major bronchi.• Hilar enlargement/mediastinal mass.• Pleural/pericardial effusion.• Raised paralyzed hemidiaphragm.• Direct chest wall invasion such as rib destruction or soft

tissue mass.


Investigation and Stagingof Bronchial Carcinoma

• Plain chest radiograph and CT are the routineimaging modalities for diagnosis and intrathoracicstaging.

• MRI provides additional useful informationregarding involvement of great vessels, pericardium,heart, carina and aortopulmonary window andsuperior sulcus.

• PET provides accurate assessment of the intratho-racic lymph node involvement and is useful for evalu-ating recurrent disease.

CT remains superior to MRI in the diagnosis of lung lesions,especially small parenchymal lesions, near the pleura ordiaphragm. PET using [18F]fluorodeoxyglucose (FDG) hashigher sensitivity and specificity than CT and MRI fordiagnosing lymph node involvement by the tumor. MRI is asgood as CT for the routine diagnosis of mediastinal invasion.MRI is, however, superior to CT for assessing involvementof major mediastinal blood vessels and the carina. It isbetter than CT in demonstrating chest wall or diaphragmaticinvasion. MRI is currently the imaging modality of choicefor demonstrating the extent of the superior sulcus tumor asit provides excellent tissue contrast between the tumor andthe soft tissues of the chest wall, and also the thin layer ofextrapleural fat is better seen on MRI than on CT.

2.1.1.5 Boerhaave’s Syndrome

Boerhaave’s syndrome is the spontaneous rupture of thedistal esophagus and usually presents with acute severe chestpain. It is caused by violent retching and vomiting usuallyafter an alcoholic binge. The sudden increase in the intralu-minal pressure causes a full-thickness esophageal tear. It is


Figure 2.1.1.5. Boerhaave’s syndrome. Water-soluble swallowshowing extravasation of the contrast medium from the distalesophagus into the mediastinum.


the most serious perforation of the GI tract carrying a veryhigh mortality rate (70%). The tear is vertical and typicallymeasures 1 to 4 cm. It is most commonly located on the leftlateral wall of the distal esophagus, just above the gastroe-sophageal junction. Rarely, it occurs in the cervical or upperthoracic esophagus where it has a better prognosis.

Prompt imaging is crucial, as large tears often requireimmediate surgical intervention. Plain chest radiographfindings include:

• Widening of the mediastinum• Pneumomediastinum: manifest by radiolucent air streaks

along the lateral border of aortic arch and descendingthoracic aorta

• Left-sided pleural effusion

CT in the imaging test of choice but is usually unable to locatethe exact anatomic site of esophageal tear. CT demonstrates:

• Extraluminal air• Extravasation of oral contrast medium in the lower

mediastinum surrounding the esophagus• Pleural and/or pericardial fluid collections

X-ray swallow with water-soluble contrast media showsextravasation from the distal esophagus into the mediastinumand extension into the adjacent fascial planes with large tears.


1. Greene R, McCloud TC, Stark P. Pneumothorax. SeminRoentgenol 1977;12:313–325.

2. Khan IA, Nair CK. Clinical, diagnostic, and managementperspectives of aortic dissection. Chest 2002;122(1):311–328.

3. Set PAK, Flower CDR, Smith IE, et al. Hemoptysis: comparativestudy of the role of CT and fiberoptic bronchoscopy. Radiology1993;189:677–680.

4. Laurent F, Montaudon M, Corneloup O. CT and MRI of lungcancer. Respiration 2006;73(2):133–142.

5. Nehoda H, Houmont K. Boerhaave’s syndrome. N Engl J Med2001;344:138–139.


2.1.2 Abdominal Pain

Patients with acute abdominal pain present a diagnosticand management challenge to the general surgeon. Plainabdominal radiographs remain the first imaging investigationin these patients and may provide a specific diagnosis in somecases. Increasingly, additional imaging with US, CT, and MRIis performed early in the management of these patients tofacilitate a rapid definitive diagnosis.

Figure 2.1.2A. Small bowel obstruction. Supine abdominal X-ray(AXR) showing multiple dilated gas-filled loops of small bowel.

Figure 2.1.2B,C. Small bowel obstruction. (B) Erect AXR on thesame patient showing multiple fluid levels. (C) CECT (differentpatient) showing dilated loops of small bowel with the string ofbeads sign (arrow). (Continued)

Figure 2.1.2D,E. (Continued) Small bowel obstruction. (D) CECTon the same patient showing a Spigelian hernia (arrow) as the causeof the small bowel obstruction. (E) Axial CECT showing extensivewall thickening of the ileum causing small bowl obstructionHistology revealed a primary small bowl lymphoma.


Figure 2.1.2F. Small bowel obstruction. Coronal reformattedimages of CECT of a different patient with small bowl obstructiondue to adhesions; note the transition zone (arrow) and the dilatedbowl loops (arrowheads).

2.1.2.1 Small Bowel Obstruction

In mechanical small bowel obstruction (SBO), swallowed airand intestinal secretions fill the dilated proximal small boweland there is reduction in the caliber and gas content of largebowel distal to the obstruction. Features of SBO on plainabdominal radiograph are

• Dilated gas-filled loops of small bowel, greater than 3-cmdiameter, which tend to be central, numerous, and in thecase of the jejunum have valvulae conniventes that extendright across the bowel.


• Multiple fluid levels on an erect abdominal radiograph.• String of beads sign on an erect abdominal radiograph,

due to small amount of gas trapped between valvulaeconniventes.

• The small bowel may be completely filled with fluid,especially with a longer standing degree of obstruction,giving the appearance of “gasless” abdomen.

• Absence of gas or feces in the large bowel.• All the above signs may be absent in proximal SBO, where

a dilated stomach may be the only sign.

These changes may appear after 3 to 5 hours and are usuallypresent after 12 hours from the onset of symptoms. Often,the plain abdominal radiograph will not show the causeof obstruction, but there are several important causes thatshould be diagnosed on plain radiographs. The presence ofgas below the line of the inguinal ligament may indicate anincarcerated femoral or inguinal hernia, a cause of SBO inabout 15% of cases. Gas in the biliary tree and an opaquegallstone in the right iliac fossa are the classic features ofa gallstone ileus. It should be remembered that adhesivedisease is the cause of SBO in about 50% of cases.

CT will confirm the presence of SBO and also provideadditional information regarding the level and the causeof obstruction. It will, in addition, give staging informationif a malignancy is the cause of SBO. CT is the imagingtechnique of choice in diagnosis of small bowel strangulation,being of great value in urgent surgical management of thesepatients.

2.1.2.2 Large Bowel Obstruction

The most common cause of large bowel obstruction (LBO) inthe Western world is a tumor, with rectosigmoid carcinomabeing the most common (65% at this location). This isclosely followed by diverticulitis. Because LBO affects muchmore commonly the left colon, plain abdominal radiographsusually suggest the diagnosis. Dilated (more than 5-cmdiameter), gas-filled loops of large bowel that tend to beperipheral and few in number are seen proximal to the level


Figure 2.1.2.2A. Cecal volvulus. Supine AXR showing a large gas-filled viscus in the center of the abdomen. (Continued)

of obstruction with little or no gas present distal to it. If theileocecal valve is competent, little or no gas is seen in thesmall bowel, whereas multiple dilated gas-filled small bowelloops are present when the ileocecal valve is incompetent. Inthe latter, the appearances can be identical with pseudoob-struction (see later). With long-standing obstruction, thececum is at risk of perforation.


Figure 2.1.2.2B. (Continued) Cecal volvulus. Erect AXR showingan air-fluid level within the dilated cecum.

Single-contrast enema is often performed as an emergencyinvestigation prior to surgery in order to confirm the presenceand determine the level of obstruction. Usually, the infor-mation provided by the combination of plain abdominalradiograph and contrast enema is adequate for appropriatesurgical management. In the situations when the plain radio-graph findings are equivocal or when the patient is unable totolerate a contrast enema, CT can provide comparable infor-


Figure 2.1.2.2C. Cecal volvulus. Sigmoid volvulus. Supine AXRshowing a markedly dilated loop of sigmoid colon with a distinctmidline crease that corresponds with twisted mesenteric root (coffeebean sign).

mation regarding the level and cause of obstruction as well asstaging information if a colonic carcinoma is demonstrated.

Cecal volvulus is a surgical emergency, and the diagnosiscan be promptly made on a plain abdominal radiograph withno need for further imaging. Features of cecal volvulus are

• Markedly dilated cecum containing few haustral markings.• Large gas-filled viscus, which may lie virtually anywhere

in the abdomen but is more frequently positioned in theleft upper quadrant.


• Marked gaseous or fluid distension of the small bowel,which also fills the empty right iliac fossa.

• Attached gas-filled appendix.• Collapse of the left side of the colon.

Sigmoid volvulus usually occurs in the elderly or in insti-tutionalized psychiatric patients. The diagnosis should beconfidently made on a plain abdominal radiograph. Bariumenema may be used in equivocal cases. Features of sigmoidvolvulus are

• A dilated ahaustral bowel loop with apex under the lefthemidiaphragm, above the level of the T10 vertebra.

• Coffee bean sign: markedly dilated loop of sigmoid colonwith a distinct midline crease that corresponds with twistedmesenteric root.

• Bird of prey sign: tapered end of barium column on bariumenema.

2.1.2.3 Pseudoobstruction

Pseudoobstruction, or Ogilvie’s syndrome, is marked colonicdistension without a mechanical obstructing cause that mayoccur as a result of pharmacological, biochemical, neural,endocrine, and myopathic factors. It usually occurs inthe elderly patient and may be self-limiting or associatedwith common medical conditions such as chest infection,myocardial infarction, and so forth. Plain abdominal radio-graphs may be indistinguishable from LBO, demonstratingdilated large and small bowel loops, and a single-contrastenema or CT is usually indicated to exclude mechanicalobstruction in order to avoid inappropriate surgical inter-vention, which can be disastrous.

2.1.2.4 Perforation of Hollow Viscus

The most common cause of pneumoperitoneum is perfo-ration of peptic ulcer followed by diverticulitis and malig-nancy. An erect chest radiograph and an abdominalradiograph, usually taken supine, should always be obtained


Figure 2.1.2.3. Pseudoobstruction. Supine AXR showing dilatedlarge and small bowel loops. Note the enormous distension of thececum.

if perforation is suspected. Both are very sensitive, and aslittle as 1 mL of free air can be detected on an erect chestradiograph or a left lateral decubitus abdominal radiograph.On the erect chest radiograph, air is seen under one orboth diaphragms and if under both results in the continuousdiaphragm sign.

Figure 2.1.2.4A,B. Perforation of hollow viscus. (A) Erect CXRshowing large amount of free subdiaphragmatic air. (B) CECTdemonstrating free intraperitoneal air (arrows) and fluid (arrow-heads) after gastric perforation.


Figure 2.1.2.4C. Perforation of hollow viscus. Supine AXR in thesame patient showing Rigler’s sign (arrows).

Signs of free intraperitoneal air on a supine abdominalradiograph are

• Air overlying or outlining solid organs such as liver andspleen (lucent liver sign)

• A triangle of air outlining Morrison’s pouch (Doges capsign)

• Air outlining intraabdominal structures such as falciformligament, umbilical median, medial and lateral ligaments(inverted V sign)


• Bowel wall outlined by air both inside and outside (Rigler’ssign)

• Centrally placed intraperitoneal free air (football sign) andscrotal air in children

• Cupola sign of air under the central diaphragm

It is very important to be able to recognize conditions thatcan simulate pneumoperitoneum because an observationalerror may lead to unnecessary surgery. Chilaiditi’s syndromein which the colon is interposed between the liver andthe diaphragm can mimic pneumoperitoneum, but usuallyhaustral folds can be seen that will allow identification of thecolon. A gas-containing subphrenic abscess may also mimica pneumoperitoneum as can basal pulmonary atelectasis. Onthe left side, a gas-distended fundus of the stomach maycause confusion, and clarification by a decubitus film may benecessary. Postoperative air may sometimes cause confusion,but this should have resolved by 5 to 7 days and shoulddecrease in size with time.

Where the plain radiographs are equivocal, then CT isthe most sensitive imaging technique for diagnosis of freeintraperitoneal air. A small amount of free intraabdominalair can be seen anterior to the liver or midline abdomen(as the mobile air collects anteriorly with the patient in thesupine position) and in the peritoneal recesses or retroperi-toneal spaces. This is best appreciated by reviewing theimages on “lung window” settings. CT may identify thecause of pneumoperitoneum and can offer additional infor-mation to plain radiographs. X-ray contrast studies canalso be performed to confirm a perforation. Water-solublecontrast medium administered orally or via a nasogastrictube combined with fluoroscopic imaging can often identifythe location of a perforation in the proximal GI tract.Urgent surgery is usually required for a perforated hollowviscus.

2.1.2.5 Acute Appendicitis

Acute appendicitis is the most common cause of anabdominal surgical emergency. The diagnosis is usually


made on the basis of clinical history and physical exami-nation with no need for imaging. Sometimes, however,the clinical findings are equivocal, and increasingly CT isused to confirm the diagnosis, although concerns aboutradiation exposure indicate that it should only be used whenappropriate.

Plain Abdominal Radiograph Findingsin Acute Appendicitis

• Calcified appendicolith (10%)• Right iliac fossa mass• Localized ileus• Loss or right psoas margin and blurring of properi-

toneal fat line• Extraluminal gas collections• Pneumoperitoneum• Scoliosis concave to the right

Plain abdominal radiographic findings are nonspecific andusually unhelpful. They may show an appendicolith. CT isthe most accurate technique for confirming the diagnosis ofappendicitis and assessing the severity and possible compli-cations, with a sensitivity and specificity of 100% and95%, respectively. CT findings include a distended appendixmeasuring more than 6 mm in diameter, which is thick-walled and may enhance after administration of intravenouscontrast medium. An appendicolith can be seen in 25% ofthe cases. Associated inflammatory changes include streakingof the periappendiceal fat, fluid collection owing to abscessformation, thickening of the cecal and/or terminal ileum wall,and thickening of the anterior renal and adjacent fascialplanes.

Graded-compression US has a recognized value inthe diagnosis of acute appendicitis in children. Graded

Figure 2.1.2.5A,B. Acute appendicitis. (A) CECT demonstratinga dilated appendix (arrow). Note the enhancement of the wall ofthe appendix and stranding of the pericecal fat planes. (B) Anappendicolith (arrow) is noted.

Figure 2.1.2.5C,D. Acute appendicitis. (C) CECT axial. (D)CECT in a different patient with appendicitis (arrow) and abscessformation in the wall of the cecum (arrowheads). Note that it isunusual to see the presence of luminal area in acute appendicitis.(Continued)


Figure 2.1.2.5E. (Continued) Acute appendicitis. Coronal refor-matted images (different patient) demonstrating an appendicularabscess (arrow). An appendicolith is again noted.

compression is applied with the transducer over the rightiliac fossa in order to displace bowel gas and examinethe appendix. In a patient with appendicitis, the appendixappears as a tubular noncompressive, aperistaltic structurethat measures more than 7 mm in its transverse diameter. An


appendicolith, casting posterior acoustic shadowing, may beseen. The surrounding inflammatory mass appears heteroge-neous, and an abscess or fluid collection may be present. USin expert hands potentially offers a sensitivity and sensitivityof 98%. The choice between US and CT depends on the localavailability and expertise, but US is preferred in childrenand pregnant women because of lack of ionizing radiationand in younger women where there is higher incidence ofpelvic inflammatory disease. Imaging, however, should notbe a substitute for adequate clinical skills and should only berequested when there is clinical uncertainty, thus avoiding thedelay in prompt surgical treatment or inappropriate radiationexposure.

2.1.2.6 Acute Cholecystitis

Acute cholecystitis results from cystic duct obstruction byan impacted gallstone in more than 90% of cases. Patientsusually present with classic symptoms and signs of rightupper quadrant pain and tenderness, and the diagnosis willbe confirmed by US if surgery is contemplated during thefirst admission. Apart from confirming the diagnosis, US maydetect other causes of acute abdominal pain such as rightrenal obstruction.

Ultrasound Features in AcuteCholecystitis

• Gallstone: mobile hyperechoic foci that cast posterioracoustic shadowing

• Tenderness on compression over the gallbladder(sonographic Murphy’s sign)

• Thickening of gallbladder wall greater than 3 mm• Pericholecystic fluid• Distended gallbladder

Figure 2.1.2.6A,B. Acute cholecystitis. (A) CECT showing aninflamed gallbladder and a calcified stone in the common bile duct(arrow). (B) Axial CECT in a septic patient showing lack of mucosalenhancement of the gallbladder (arrows) suggestive of a necrotizingcholecystitis.

Figure 2.1.2.6C,D. Acute cholecystitis. (C) Note the dilatedgallbladder with enhancing, thickened wall and stranding of thesurrounding fat planes as well as the large laminated gallstone.(D) Coronal reformatted image of this CECT showing the extentof the necrosis (arrows).


Plain abdominal radiograph findings are nonspecific andusually unhelpful. They include calcified gallstones (20%),right upper quadrant mass due to an enlarged gallbladder,duodenal or high colonic ileus, and rarely air within thebiliary tree (in cases of gallstone ileus).

On US, the two most important features are the presenceof gallstones and maximal tenderness on compressionover the gallbladder (sonographic Murphy’s sign), whichis highly specific for acute cholecystitis. Both scintig-raphy using technetium-99m (99mTc)-labeled derivativesof iminodiacetic acid (HIDA) and US are diagnosticallyaccurate, and the choice between them may reflect localexpertise and availability. HIDA scintigraphy has a 100%negative predictive value and a good sensitivity. A positiveexamination consists of nonvisualization of gallbladderbut prompt visualization of the common bile duct andduodenum 1 hour after injection. False-positive results occurin alcoholic liver disease and in patients receiving parenteralnutrition.

CT is not the primary imaging modality because of its lowsensitivity for gallstones. It is, however, of good value inimaging possible complications such as gangrenous cholecys-titis, perforation of gallbladder resulting in abscess formationor biloma, Mirizzi’s syndrome, and so forth.

2.1.2.7 Acute Pancreatitis

The most common cause of acute pancreatitis in Westerncountries is alcohol followed by cholelithiasis. Less frequentcauses are metabolic disorders such as hyperparathyroidism,trauma, abdominal surgery, viral infections, drugs, andso forth. The plain abdominal radiograph is unreliable,being normal in more than 75% of patients with acutepancreatitis, but can demonstrate a number of features(see box).


Plain Film Findingsin Acute Pancreatitis

• Gallstones• Pancreatic calcifications with chronic pancreatitis• Gasless abdomen• Generalized or paralytic ileus in the left upper

quadrant• Sentinel loop and colon cutoff sign• Separation of greater curve of stomach from trans-

verse colon• Loss of left psoas outline• Extraluminal air bubbles• Left pleural effusion• Elevated left hemidiaphragm

The diagnosis of acute pancreatitis is usually straight-forward based on clinical history, findings, and hyperamy-lasemia. In these cases, US is primarily indicated to detectthe presence of gallstones as a possible cause because thepancreas is not always visible due to the accompanying smallbowel ileus. When visualized, the pancreas may be enlarged,hypoechoic, and ill defined. Peripancreatic fluid and possiblecomplications such as abscess and pseudocyst formation canbe identified. US is unable to accurately assess pancreaticnecrosis, which many consider the single most importantdeterminant of morbidity and mortality in these patients.

CT more reliably demonstrates all these features (exceptfor gallstones). In particular, it is the imaging techniqueof choice to assess the presence and extent of pancreaticnecrosis. After intravenous contrast medium administration,thin, small field of view sections are obtained duringpancreatic phase enhancement in addition to conventionalarterial and venous phases. In cases of mild acute pancre-atitis, the pancreas may appear normal. More commonly,

Figure 2.1.2.7A,B. Acute pancreatitis. (A) CECT showing inflam-matory changes mainly involving pancreatic head, which appearsenlarged and contains areas of lack of parenchymal enhancementsuggestive of edema. (B) There are numerous gallstones within thegallbladder.


the gland appears enlarged with increased attenuation in theperipancreatic fat and adjacent fascial plane thickening. Thepancreas itself normally shows homogeneous enhancement,but in severe acute pancreatitis necrotic tissue appears asareas of reduced or absent enhancement in the parenchyma.The presence of parenchymal air is highly suggestive ofinfection although fistulation to the gastrointestinal tractcan result in identical appearances. CT is very sensitivefor demonstrating complications such as pancreatic abscess,adjacent fluid collections, or pseudocyst formation. It isparticularly helpful for vascular complications including bothpseudoaneurysm formation and thrombosis of the splenicor portal vein. The Balthazar CT Severity Index, which hasbeen shown to have a good correlation with morbidity andmortality of the disease, can be calculated on the basis of theCT findings.

Recommendations forContrast-Enhanced CTin Acute Pancreatitis

• Patients who do not improve within 72 hours of thecommencement of conservative management

• To confirm the diagnosis of acute pancreatitis and toevaluate the extent and severity of disease

• Patients with a Ranson score greater than 3• To diagnose complications• To guide interventional procedures

2.1.2.8 Small Bowel Ischemia

Different processes can lead to small bowel ischemia, themost common being mesenteric thrombus or embolus, infil-tration, and trauma. It represents a serious surgical conditionthat can be difficult to diagnose clinically and often requiresprompt imaging and treatment.


�Figure 2.1.2.8A,B. Small bowel ischemia. (A) Axial and (B)coronal reformatted images of a CECT study showing fillingdefects within the superior mesenteric artery (arrow) and vein(arrowhead).

Figure 2.1.2.8C. Small bowel ischemia. CECT in a different patientdemonstrating an abnormal loop of small bowel that shows athickened and unenhancing wall (arrows).


Plain abdominal radiographic findings depend on theseverity of the disease. Nonspecific dilated bowel loops withmultiple fluid levels or fluid-filled loops are a frequentfinding. Thickening of the bowel wall (“thumb printing”)may be visible, which is due to submucosal hemorrhage andedema. In severe cases, gas may be seen within the bowelwall and/or the mesenteric and portal veins. Barium studieswill show separation of the bowel loops and thickening ofvalvulae conniventes. Mucosal ulceration can be seen inadvanced cases.

Contrast-enhanced CT may provide an early diagnosisof mesenteric ischemia by demonstrating not only thedilated fluid-filled loops of bowel with wall thickeningand ascites but more importantly the lack of mesentericvascular enhancement after administration of intravenouscontrast media. Occasionally, thrombus may be visible ina mesenteric artery or vein and gas within the mesen-teric veins and/or bowel wall. Reconstruction of vascularanatomy using multislice CT will further assist in an accuratediagnosis.

Angiography was widely used to make the diagnosis priorto CT and remains valuable for equivocal cases. It will showfeatures of occlusion, vasoconstriction, or vascular beading.Emboli are typically seen at major branching points distal tothe first 3 cm of superior mesenteric artery.

2.1.2.9 Renal Colic

Renal colic is usually caused by stone disease but mayalso arise secondary to a transitional cell carcinoma of therenal pelvis or ureter. Microscopic or macroscopic hematuriaoccurs in most cases.

�Figure 2.1.2.9A,B. Urolithiasis. (A) Axial CT image showing a leftdistal ureteric stone. (B) CT coronal reformatted image confirmingthe presence of the left distal ureteric stone approximately 5 cmfrom the left vesico-ureteric junction. Also note mild dilatation ofthe left ureter proximal to the stone. (Continued)


�Figure 2.1.2.9C,D. (Continued) Urolithiasis. (C) Axial CECT ofan impacted right vesico-ureteric junction (VUJ) calculus (arrow).(D) Curved planar reformatted image of the right dilated ureter(arrowheads).

Urolithiasis: Imaging is almost always required to make aninitial diagnosis but may not be needed for uncomplicatedrecurrent disease. Plain abdominal radiograph may show acalcified opacity along the line of the urinary tract, but upto 30% of the stones are not calcified (or obscured). Intra-venous urography (IVU) is helpful in showing the degreeand site of obstruction. Features of obstruction includedilatation of the pelvicaliceal system and/or the ureter,depending on the position of the stone. US may showrenal stones and features of hydronephrosis, but it has tobe remembered that the pelvicaliceal system may appearnormal in the early phase of obstruction. US cannot reliablydemonstrate ureteric stones. Nonenhanced CT (NECT) isincreasingly used as the imaging modality of choice whenurolithiasis is suspected. It has a sensitivity and specificityof 97%, with a calculus within the ureter being pathog-nomonic. It can detect radiolucent stones as well as uretericedema surrounding a small impacted stone. Stranding of theperinephric/periureteral fat and perinephric fluid collectionsare associated findings easily detectable by CT. Confusioncan arise from the presence of phleboliths, but multiplanarreformats in coronal and sagittal planes will help resolve thedilemma.

Transitional cell carcinoma: Plain abdominal radiograph isusually normal. IVU shows single or multiple filling defectsin the renal pelvis, ureter, or bladder. One or more calycesmay also fail to opacify (phantom calyx) or there may becalyceal distension with tumor (oncocalyx). Hydronephrosisdue to tumor obstruction is an additional but uncommonfinding. US confirms these findings, but CT is indicated forstaging purposes.


2.1.3 Abdominal Sepsis

Patients with abdominal sepsis may present with localor systemic signs and frequently pose a diagnostic andmanagement challenge to the surgeon. Imaging is importantfor both diagnosis and therapy, as image-guided drainage ofintraabdominal collections is often the preferred treatmentoption. This section concentrates on imaging of abdominalcollections and the postoperative abdomen.

2.1.3.1 Intraabdominal Collections

Patients with abdominal sepsis may present with fever;abdominal pain, and/or bowel symptoms caused bysubphrenic, intrahepatic, and pelvic abscesses.

Subphrenic and subhepatic abscesses can occur aftersurgery of stomach, pancreas, spleen, splenic flexure of colon,perforating cholecystitis, or gastric and duodenal ulcer orcan develop as a complication of acute pancreatitis, appen-dicitis, cholecystitis, and perforated duodenal ulcer. A rightparacolic abscess can follow acute appendicitis or developsecondary to a subphrenic abscess, whereas a left paracolicabscess can result from perforated diverticular disease orfrom ascending pelvic infections. A pelvic abscess maycomplicate appendicitis, pelvic inflammatory disease, andlarge bowel surgery. Abscesses also occur within organs suchas liver, pancreas, and spleen.

A plain chest radiograph may show a raised hemidiaphragm,loculated gas under the diaphragm, or basal lung consolidationand/orpleuraleffusion.Theabdominalradiographcandemon-strate gas fluid level or gas bubbles that remain unchangedon sequential films. Other features include a soft tissue mass,paralytic ileus, or effacement of the fat planes.

US is an appropriate technique for suspected collections inthe upper abdomen and pelvis if localizing signs are presentbut may overlook collections. This is a particular problemin the iliac fossae due to overlying bowel gas. Collectionsappear as hypoechoic or anechoic lesions usually with irregularmargins and may be multiloculated. CT is the modality ofchoice for studying the whole abdomen and pelvis. Fluid collec-tions are well demonstrated, and rim enhancement around


Figure 2.1.3.1A,B. Right paracolic abscess. (A) CECT showing alarge multiloculated collection in the right paracolic space. Notethe presence of rim enhancement. (B) CT-guided insertion of draininto the abscess.

a collection after contrast media injection strongly suggestsan abscess. Good bowel preparation by oral contrast mediais essential to distinguish fluid-filled bowel loops from anabnormal collection. Both US and CT can guide percutaneous


aspiration and drainage. MRI is not widely used for acuteintraabdominal sepsis but is particularly helpful in preoper-ative imaging of pelvic fistulae due to inflammatory boweldisease, most commonly Crohn’s disease.

In the majority of the patients, the diagnosis is estab-lished by CT and/or US, but when those are negative orwhen there are no localizing signs of the sepsis, a labeledwhite cell scintigram is a useful diagnostic option. It offersa sensitivity and specificity of 95% and 90%, respectively.Acute intraabdominal sepsis can be investigated using eitherindium-111 (111In) or 99mTc-labeled white cells, although thelatter gives images of better resolution and is preferred ifthere is coexistent inflammatory bowel disease. Sequentialimaging is essential in order not to miss an abscess in commu-nication with bowel lumen.

Imaging of Abdominal Sepsis

• US is a good initial imaging method for upperabdomen and pelvis when localizing signs arepresent, but not for the iliac fossae where obscuringgas may lead to false-negative results.

• CT is the modality of choice for diagnosis wherelocalizing signs to the upper abdomen or true pelvisare absent.

• Both US and CT can be used for guiding percuta-neous aspiration and drainage where appropriate.

• White cell scanning is an alternative investigationwhen there are no localizing signs. It demon-strates enteric communication and can identify sepsisat any site.

• MRI is very helpful is cases of inflammatory boweldisease complicated by perineal fistulae.

In patients with genuine pyrexia of unknown origin,gallium-67 (67G) should be the first imaging option. This isbecause only 10% of cases with pyrexia of unknown origin(PUO) are caused by pyogenic sepsis, and in the absence


of neutrophils, a labeled white cell scintigram will not bepositive. Other conditions such as lymphoma, melanoma,tuberculosis, sarcoidosis, and so forth, show avid galliumuptake, making it nonspecific in imaging of the abdominalsepsis. The value of gallium imaging is to localize a potentialcause that can subsequently be investigated by other imagingmodalities such as US, CT, or MRI.

Suggested Diagnostic Algorithm in Abdominal Sepsis

Suspected Abdominal Sepsis

No Localising Signs Localising Signs

White Cell Scan

PercutaneousDrainage

– +

LowerAbdomen

UpperAbdomen

US CT

Stop

Stop Surgery


2.1.3.2 Imaging of Postoperative Abdomen

Imaging is valuable for investigating postoperative complica-tions. The clinical picture may be that of an acute abdomenor intraabdominal sepsis. Plain abdominal radiographs stillremain the first imaging test, and the same diagnostic criteriaas for the preoperative radiograph apply. As mentionedbefore, both US and CT are used to detect abnormal fluidcollections, abscesses, and so forth, but CT is usually the morepractical option because it provides a rapid, noninvasive, andglobal view of the abdominal cavity, unimpeded by extensivebowel gas from concomitant ileus, wounds, surgical dressings,and so forth.

Pneumoperitoneum is a common feature on the postoper-ative plain abdominal radiograph, being present in 60% ofpostlaparotomy patients. Intraperitoneal air takes between 1day and 3 weeks to reabsorb dependent on the patient’s bodyhabitus. Gas is more rapidly reabsorbed in obese patientswho generally have no residual gas after the fifth postoper-ative day. It is important to note that any increase in theamount of postoperative air indicates an anastomotic leak ora hollow viscus perforation. CT is the most sensitive methodfor the assessment of pneumoperitoneum and will also detectabnormal air collections in abdominal viscera.

Paralytic ileus is common and may simulate or coexist withobstruction. Small bowel obstruction due to adhesions maydevelop a few days after a laparotomy. Patients may developanastomotic leaks and/or intraabdominal abscesses. Imagingfeatures of these conditions are described in detail in theprevious sections.


1. Marincek B. Nontraumatic abdominal emergencies: acuteabdominal pain: diagnostic strategies. Eur Radiol 2002;12(9):2136–2150.

2. Stapakis JC, Thickman D. Diagnosis of pneumoperitoneum:abdominal CT versus upright chest film. J Comput Assist Tomogr1992;16:713–716.

Figure 2.1.3.2A,B. Imaging of postoperative abdomen. (A)Scanogram and (B) axial CECT images showing a retained swab asdemonstrated by the radiopaque material. Note extensive mass dueto gossypiboma.


3. Rao PM, Boland GWL. Imaging of acute right lower abdominalquadrant pain. Clin Radiol 1998;53:639–649.

4. Ng CS, Watson CJ, Palmer CR, et al. Evaluation of earlyabdominopelvic computed tomography in patients with acuteabdominal pain of unknown cause: prospective randomisedstudy. BMJ 2002;325:1387–1390.

5. Lee R, Tung HKS, Tung PHM, et al. CT in the acute mesentericischaemia. Clin Radiol 2003;58:279–287.

2.2 Mass

2.2.1 Imaging of Abdominal Massesby Their Location

Many intraabdominal tumors when advanced may present aspalpable abdominal masses. Imaging confirms and diagnosesthese masses and is particularly helpful for diagnosing anddetecting smaller tumor masses that are not easily palpable.

This section concentrates on imaging of tumors ofliver, adrenal, body and tail of pancreas, retroperitoneallymphadenopathy, and sarcomas. Imaging of pancreatichead tumors is described under “Jaundice” (Section 2.4)imaging features of renal cell carcinoma are given in under“Hematuria” (Section 2.3.2), and imaging of gastrointestinaltumor is described in detail under “Bleeding” (Section 2.3).

2.2.1.1 Liver Tumors

Liver tumors can be classified as primary and metastatictumors. Primary tumors may be benign or malignant. USis widely used in liver imaging, especially for the follow-up of the patients with cirrhosis, to detect small hepatocel-lular carcinomas. Other benign lesions, such as hemangiomas,adenomas, or focal nodular hyperplasia (FNH), can bedetected incidentally during US. Capillary hemangiomas arethe most common benign tumors of the liver and have aclassic appearance on US examination of a well-definedhyperechoic, often slightly lobulated mass. Unfortunately,this appearance may be mimicked by some metastases,

2.2 Mass 67

particularly from the gastrointestinal tract, so in the appro-priate clinical situation further imaging may be required.US findings on focal nodular hyperplasia and adenomaare usually nonspecific. MRI is now considered the mostsensitive and specific imaging technique for the diagnosisof these benign liver lesions. Hemangiomas are of highsignal intensity, similar to water and higher than spleen,on T2-weighted (T2W) images. They rapidly enhance ina centripetal fashion after gadolinium diethylenetriaminepenta-acetic acid (Gd-DTPA) administration (light bulbsign.) FNH appears as an isointense to minimally hypointenselesion on T1-weighted (T1W) images and hyperintense onT2W images. The central scar, if present, is of low signalintensity on T1W images and of high signal intensity on T2Wimages. After Gd-DTPA injection, the lesion enhances avidlyand homogeneously while the central scar remains initiallyof low signal intensity, although it may demonstrate delayedenhancement. On MRI examination, simple adenoma hassimilar appearances to FNH.

Combination of US and triphasic contrast-enhanced CT(CECT) can accurately suggest a definitive diagnosis in mostcases of malignant liver lesions. This section provides adetailed description of imaging findings in hepatocellularcarcinoma and liver metastasis.

Hepatocellular carcinoma (HCC) is the most commonprimary liver tumor. It may present either as a single largemass or as a multifocal diffuse lesion. The tumor usuallydevelops in a cirrhotic liver, for example, due to chronicviral hepatitis (HBV and HCV cirrhosis) but can occur denovo within a normal liver. In cirrhotic livers, all imagingtechniques have limited sensitivity and specificity. US iswidely used as a screening technique for at-risk patientgroups and may demonstrate a hypoechoic, heterogeneous,and less frequently a hyperechoic lesion. Features of under-lying liver cirrhosis such as a small, nodular hyperechoic liverwith associated splenomegaly, varices, and ascites can be wellappreciated on US.

HCC appears as a low-attenuation single or multifocalmass on unenhanced CT images and necrosis, calcification,


Figure 2.2.1.1A. Hepatocellular carcinoma. Arterial phase of aCECT demonstrating an enhancing lesion in the superior aspect ofthe right lobe of the liver (arrow) consistent with hepatocellularcarcinoma. Note the presence of ascites (arrowheads).

and fat may be demonstrated. Biphasic CECT, with arterialand portal phase imaging, increases the sensitivity of thetechnique as approximately 10% of HCC lesions are onlyvisible during the arterial phase. The tumor shows hetero-geneous enhancement on arterial phase images and appearsas a heterogeneous low-attenuation lesion, sometimes indis-tinguishable from normal liver parenchyma, on portal phaseimages. HCC demonstrates intense enhancement on CThepatic arteriography. There is no enhancement during CTarterial portography.

�Figure 2.2.1.1B,C. Liver metastasis. Portal phase (B) axial and(C) coronal CECT images demonstrating multiple low-attenuationlesions within both lobes of the liver consistent with multiple livermetastasis.


Frequently, it can be very difficult to distinguish HCCfrom regenerating cirrhotic nodules on US and CTimages. MRI can be helpful in these cases. HCC appearshypointense on T1W images and hyperintense on T2Wimages, and cirrhotic nodules may demonstrate increasedsignal intensity on T1W images and low signal intensityon T2W images. The use of liver-specific contrast mediumagents, such as super paramagnetic iron oxide (SPIO), mayimprove the sensitivity of MRI in detecting small HCC.Magnetic resonance angiography (MRA) allows nonin-vasive, accurate assessment of hepatic vessels, portal vein,and inferior vena cava prior to hepatic resection or livertransplantation.

Angiography typically demonstrates a hypervascular tumorwith marked neovascularity and arteriovenous shunting.

Liver metastases may be demonstrated with US, CT, orMRI with an increasing order of sensitivity. Although theyhave relatively specific features, they may be mimicked bybenign causes such as liver abscesses, hemangiomas, and soforth. A tissue diagnosis is therefore appropriate, and whereimpossible (such as lesions less than 5 mm), serial follow-upimaging is indicated.

US typically demonstrates multiple solid liver lesions witha hypoechoic rim. Biopsy of larger lesions can be performedunder US guidance and is especially useful when the liver isthe only site of metastasis and the primary tumor is unknown.CT is excellent in demonstrating liver metastasis especiallywhen larger than 10 mm. They can be hypovascular such asthose from lung, gastrointestinal tract, pancreatic, bladder,uterine tumors, most breast cancer cancers, and so forth,or hypervascular in cases of renal cell carcinoma (RCC),thyroid carcinoma, melanoma, endocrine tumors, and soforth. Although the majority of lesions are detectable onunenhanced CT, the addition of CECT (portal phase images)increases the sensitivity by 5% to 10%. Typically, CT demon-strates randomly distributed lesions throughout the liverwith low-attenuation center and peripheral rim enhancementin case of hypovascular metastasis. Hypervascular metas-tases appear as high-attenuation lesions in late arterial phase

2.2 Mass 71

images. MRI is also a comparably accurate technique fordemonstrating liver metastasis but is not routinely used inpractice owing to availability and costs compared with USor CECT examinations. [18F]fluorodeoxyglucose–positronemission tomography (FDG-PET) is increasingly used wherehepatic resection of a solitary metastasis is being considered,but mainly for the detection of extrahepatic metastaticdisease.

2.2.1.2 Adrenal Tumors

The detection of adrenal masses has significantly increasedwith the widespread use of cross-sectional imaging, and theyare revealed in 5% to 10% of CT or magnetic resonance(MR) examinations of the abdomen. The majority of adrenalmasses are incidental benign adenomas, even in patientswith known primary malignancy. However, the adrenal isa common site of metastasis, particularly from lung, breastcancer, and melanoma primaries. The accurate differenti-ation between an adenoma and a metastasis becomes crucialin patients with known primary malignancy, particularly lungcancer, as adrenal metastasis indicates advanced disease andcurative surgery is not warranted. In practice, a combinationof CT, MRI, and PET is used to characterize adrenal massesin the oncology patient.

Certain CT findings such as the shape of the gland, size ofthe lesion, and change in size over time are useful in differ-entiating benign from malignant lesions. Adenomas tend tohave smooth margins, are smaller, and show little changeover time. Large lesions (especially if greater than 3 cm)that increase in size with time and have an irregular contourare likely to represent adrenal carcinomas or metastasis.These features are useful but nonspecific. There are two maincriteria used to reliably differentiate benign adenomas frommalignant lesions: intracellular lipid content and vascularenhancement pattern. A dedicated adrenal CT protocolshould be performed. It consists of an NECT followedby a CECT with images obtained in portal (70 seconds)

Figure 2.2.1.2A,B. Pheochromocytoma. (A) T2-weighted axial MRshowing a large, high signal intensity mass in the right adrenal. (B)The mass is of low signal intensity on T1-weighted coronal image.Appearances are in keeping with an adrenal pheochromocytoma.

2.2 Mass 73

Figure 2.2.1.2C. Pheochromocytoma. Typical contrast enhance-ment (arrow) on a coronal T1-weighted, fat-suppressed sequenceof a right adrenal pheochromocytoma (different patient).

and delayed phases (10 to 15 minutes). Thin collimation(3 mm) and rapid bolus injection of intravenous contrastmedium (3 mL/s) are used. The majority of adenomas (80%)contain intracellular lipid that results on low attenuation<10 Hounsfield units (HU) on NECT, thus reliably distin-guishing them from malignant lesions, and no further imagingis required. Around 20% of adenomas are lipid-poor makingdifferentiation from malignant lesions practically impossibleon NECT alone. The attenuation value and percentageenhancement washout of the lesion at delayed CECT arevery useful in these cases. A HU of less than 37 on delayed


images and 50% or greater enhancement washout value isdiagnostic of an adenoma (sensitivity of 96% and specificityof 100%).

It is important to realize that if CT findings are stillequivocal, the patient should undergo further evaluation withMRI or an adrenal biopsy to confirm a benign or a malignantlesion. Conventional T1W, T2W, and Gd-DTPA enhancedimages and chemical shift imaging are used. Adenomas are oflow signal, whereas metastases are of high signal intensity onT2W images. However, there is significant overlap betweenthe two. Enhancement pattern is similar to that seen duringCT imaging. Chemical shift or in-phase and out-of-phaseimaging is used to detect lipid and relies on the differentresonance frequency rates of protons in fat and watermolecules. It is the most sensitive method for differenti-ating adenomas from metastasis. Adenomas appear darkeron out-of-phase than on in-phase images as a result of signalreduction due to cancellation of the lipid and water protonsignals. In adrenal metastases, which do not contain lipid,there is no signal loss on out-of-phase images, and thus therelative signal intensity remains the same on both sequences.More recently, PET has been used in the evaluation of thenonfunctioning adrenal masses. Unlike previously discussedimaging modalities, a positive PET study accurately identifiesa malignant mass rather than an adenoma. As with othertumors, PET is not reliable in diagnosis of small lesions(less than 10 mm).

Adrenal carcinomas are rare, presenting as large, usuallyunilateral adrenal masses. The patient may present witha palpable mass, abdominal pain or, in 50% of cases,the Cushing syndrome. The CT appearance is that of alarge mass (>5 cm) with central necrosis and calcifica-tions (20%) that shows heterogeneous contrast mediumenhancement. Tumor extension into the renal vein andinferior vena cava (IVC) can be reliably identified onCT. MRI is especially helpful in evaluating IVC invasionand delineating tumor-liver interface in right adrenalcarcinomas.

2.2 Mass 75

Suggested Algorithm for Diagnosis of Adrenal Massesin Oncology Patients

NECT

Delayed CECT (10–15 min)

HU < 10 HU > 10

Benign In- and out-of-phase MR

HU > 37 andwashout < 50%

HU < 37 andWashout > 50%

BenignBiopsy

Benign Biopsy

No signalreduction

Signalreduction

2.2.1.3 Tumors of the Pancreas

Pancreatic tumors may arise from the endocrine or exocrinepancreatic tissue. Ductal adenocarcinoma is the mostcommon pancreatic tumor arising from the ductal epitheliumof the exocrine pancreas. They occur in the pancreatic headin 65% of cases, with the remainder arising in the body ortail. Imaging features of ductal carcinoma of the pancreatichead are discussed in Section 2.4.1.3.

US is commonly the first imaging test performed to inves-tigate jaundice or nonspecific abdominal pain. A tumor haslower reflectivity than pancreatic tissue, and obstruction of themain pancreatic duct (normally <3 mm diameter) may also beapparent. CECT with thin collimation (3 mm) and rapid intra-venous bolus contrast medium injection is the technique of


Figure 2.2.1.3. Carcinoma of the body of the pancreas. CECTimage demonstrating a low-attenuation mass (arrow) within thenormal enhancing pancreatic body representing a pancreatic ductcarcinoma. Note the presence of a single metastases within the leftlobe of the liver (arrowhead).

choice for both diagnosis and staging of the disease. Images aretaken at different phases of contrast enhancement (i.e., arterialand portal phases). The tumor is seen as a low-attenuation areawithin the densely enhancing normal pancreatic tissue, betterappreciated in the arterial phase. CT is capable of demon-strating perivascular invasion of arterial and venous structuressuch as the superior mesenteric artery, superior mesentericvein, and splenic vein. This is crucial in the determinationof tumor resectability. Complete circumferential vascularencasement by tumor is a sign of nonresectability. CT is alsovery sensitive in detecting invasion of other adjacent structuresaswellasregional lymphadenopathyandlivermetastasis.Fine-needle aspiration cytology and biopsy samples can be obtainedunder CT guidance. Further imaging may be obtained byendoscopic or laparoscopic US. Although MRI may be helpfulto evaluate vascular invasion, generally it offers no diagnosticimprovement compared with CT and is not therefore routinelyindicated.

2.2 Mass 77

2.2.1.4 Retroperitoneal Sarcoma

Retroperitoneal sarcoma is a primary malignant retroperi-toneal tumor of mesodermal origin. It is usually a largeheterogeneous mass that displaces the retroperitoneal

Figure 2.2.1.4A,B. Retroperitoneal sarcoma. CECT imagesdemonstrating a pelvic mass (arrows in A) of mixed attenuationthat is causing right-side hydronephrosis (B). Histology showed aretroperitoneal liposarcoma.


structures. Based on the tissue of origin, retroperitonealsarcoma comprises a spectrum of malignant tumors suchas liposarcoma, leiomyosarcoma, fibrosarcoma, rhabdom-yosarcoma, angiosarcoma, and so forth. Liposarcoma is themost common primary retroperitoneal malignant tumor andis classically located in the perinephric region.

CT is the best imaging modality for diagnosis and staging ofliposarcomas. It shows a poorly defined or well-encapsulatedlarge mass that can be of soft tissue, fatty, or mixed attenu-ation depending on histologic differentiation. The mass maycontain areas of calcifications and can invade, displace, ordistort surrounding structures. It usually shows heteroge-neous enhancement on CECT. MRI demonstrates variablesignal intensity that depends on the amount of fat content aswell as intratumoral necroses and hemorrhage. Liposarcomasare hypovascular on angiography.

2.2.2 Abdominal Aortic Aneurysm

The plain abdominal radiograph is unreliable in the diagnosisof abdominal aortic aneurysm (AAA) and any suspectedrupture. Positive signs when present (approximately 70%)depend on the outlining of an aneurysm by wall calcifi-cation or perhaps a retroperitoneal mass. US is very usefulin diagnosis and defining aneurysm diameter (the mostimportant determinant of rupture risk) but may be limitedwith regard to relationship with renal arteries and aorticbifurcation. However, if the aneurysm commences below thelevel of the superior mesenteric artery, it is unlikely that therenal arteries are involved. US can also show the presence ofthrombus and detect free intraabdominal fluid in a leakingAAA. It is widely used to follow aneurysm growth whenresection is deferred.

CT is the investigation of choice in patients who are beingconsidered for aneurysm resection. It provides an accuratemeasurement of aneurysm diameter and wall thickness andis useful in evaluating the degree of aortic calcification andpresence of thrombus. Classification of AAA into suprarenal,

Figure 2.2.2A,B. Abdominal aortic aneurysm. CT angiogram (A)axial, (B) coronal. (Continued)

Figure 2.2.2C,D. (Continued) Abdominal aortic aneurysm. CTangiogram (C) sagittal images showing an aortic abdominalaneurysm. (D) Axial CECT image of an abdominal aortic aneurysmwith dissection. Note the origin of the right renal artery (arrow)from the true lumen.

2.2 Mass 81

Figure 2.2.2E. Abdominal aortic aneurysm. Coronal reformattedimage of the same patient, showing the extent of the dissection;the true lumen (arrow) is significantly smaller than the false lumen(arrowhead).

pararenal, and infrarenal is fundamental to the surgicalapproach and is easily achieved with CT angiography usingmultislice CT and three-dimensional reconstruction. CT alsoroutinely demonstrates anatomic variants such as retroaorticleft renal vein, left-sided inferior vena cava, horseshoe kidneyalong with complications such as leakage, inflammatoryaneurysms, and periaortitis. Postoperatively, CT evaluatesleakage, abscess formation, and complications such as aorto-duodenal fistula, and so forth.


MRI, especially MRA, equals CT for vascular assessmentpreoperatively but is not widely used owing to relativecost and availability. X-ray–based angiography is now rarelyrequired prior to surgery as multislice CT and MRI usuallyprovide adequate information.


1. Kamel IR, Choti MA, Horton KM, et al. Surgically staged focalliver lesions: accuracy and reproducibility of dual-phase helicalCT for detection and characterisation. Radiology 2003;227:752–757.

2. Caoili EM, Korobkin M, Francis IR, et al. Adrenal masses:characterisation with combined unenhanced and delayedenhanced CT. Radiology 2002;222:629.

3. Mehmet Erturk S, Ichikawa T, Sou H, et al. Pancreatic adeno-carcinoma: MDCT versus MRI in the detection and assessmentof locoregional extension. J Comput Assist Tomogr 2006;30(4):583–590.

4. Kim T, Murakami T, Oi H, et al. CT and MR imaging ofabdominal liposarcoma. AJR 1996;166:829–833.

5. Iino M, Kuribayashi S, Imakita S, et al. Sensitivity and speci-ficity of CT in the diagnosis of inflammatory abdominal aorticaneurysms. J Comput Assist Tomogr 2002;26:1006–1012.

2.3 Bleeding

Both gastrointestinal hemorrhage and hematuria arecommon clinical problems and may require significantimaging investigations.

2.3.1 Gastrointestinal Bleeding

Gastrointestinal (GI) hemorrhage can be anatomicallydivided into upper GI bleeding, defined as hemorrhage froma site proximal to the ligament of Treitz, whereas bleedingdistal to this point is lower GI in origin. Diagnostic techniquesinclude endoscopy, angiography, and nuclear medicine.

2.3 Bleeding 83

2.3.1.1 Diagnosis of UpperGastrointestinal Bleeding

Endoscopy is the primary technique for diagnosis and thera-peutic intervention in upper GI hemorrhage (e.g., esophagealvarices).

2.3.1.1.1 Endoscopy Whenever GI bleeding is thought tooriginate from a site proximal to the ligament of Treitz, theprincipal investigation technique should be flexible upperGI endoscopy. The diagnostic accuracy is excellent if it isperformed within the first 12 hours of bleeding. Endoscopyis widely available and relatively noninvasive. It is of greatvalue as it can qualitatively assess the bleeding rate and thepossibility of rebleeding and allows biopsies to be obtained.It provides a definitive diagnosis in the majority of the cases

Figure 2.3.1.1.1. Endoscopy. Dieulafoy lesion in the stomach.


and offers numerous therapeutic interventions for specificlesions (i.e., injection of adrenaline into the base of the ulceror hot biopsy of small bleeding sources). If the bleedinglesion is still thought to be high small bowel (i.e., around ordistal to the ligament of Treitz), then upper GI enteroscopyis indicated.

2.3.1.1.2 Angiography Angiography is only performedwhen full endoscopy fails to locate a bleeding point or whentherapeutic embolization is indicated. Selective injection ofceliac axis and superior mesenteric artery is performed. Incases of active blood loss (bleeding rate >0.5 mL/min),extravasated contrast medium is seen into the bowel lumen.Angiography is insensitive if bleeding is intermittent orof venous origin. Angiography is valuable in detection ofvascular abnormalities such as arteriovenous malformationsand angiodysplasia.

2.3.1.1.3 Nuclear Medicine Studies Nuclear medicinestudies, either 99mTc-labeled red cells or sulfur colloid, arerarely used in the diagnosis of upper GI hemorrhage. Ableeding point shows as an area of increased uptake outsidenormal areas of uptake. Radionuclide studies are moresensitive than angiography but lack accuracy in localizingthe site of bleeding.

2.3.1.2 Causes of Upper Gastrointestinal Bleeding

There are numerous causes of upper GI bleeding, mostof them now amenable to medical rather than surgicaltreatment. They are listed in the following subsections.

2.3.1.2.1 Esophagitis, Ulcers, and Varices Esophagitiscommonly results from gastroesophageal reflux disease(GORD), which is a manifestation of peptic ulcer disease.GORD causes a spectrum of abnormalities ranging fromsuperficial esophagitis to deep penetrating ulcers. It accountsfor approximately 3% of upper GI bleeding. Barrett’sesophagus also results from GORD, wherein the normalsquamous epithelium of the distal esophagus is replaced by

2.3 Bleeding 85

Figure 2.3.1.2.1. Esophageal erosions. Classic erosive esophagitiswith the presence of reflux ulcers in the lower esophagus.

specialized columnar epithelium. Ulcers when they occur inthis situation are found at the squamo-columnar junction.Barrett’s esophagus is associated with a high incidence ofadenocarcinoma so that patients with this condition are keptunder surveillance with yearly endoscopy and biopsy todetect early dysplastic changes.

Esophageal varices can be demonstrated either byendoscopy or barium studies. Endoscopy is advantageous asit also offers the therapeutic options of injecting sclerosantsor banding the varices. There are two types of varices:uphill and downhill varices. Uphill varices are seen inportal hypertension and are caused by the diverted bloodflow via the esophagus to the superior vena cava. Theyare found in the lower esophagus and fundus of the


stomach. Downhill varices are caused by superior vena cavaobstruction, where the blood flow is diverted from head andneck via esophagus to the azygos system. They are usuallyfound in upper and mid esophagus. At barium swallow, bothtypes appear as serpiginous filling defects best seen in proneposition.

2.3.1.2.2 Gastric Erosions and Peptic Ulceration Gastro-duodenal erosions account for the majority of gastrointestinalhemorrhages. Gastric erosions are aphthous ulcers that donot penetrate the muscularis mucosa. Alcohol, salicylates,and nonsteroidal anti-inflammatory drugs (NSAIDs) are themost common causes of acute hemorrhagic gastritis. Anotherimportant cause is the stress syndrome in critically ill patientsdue to multiple trauma, sepsis, shock, and so forth.

At double-contrast barium studies, gastric erosions appearas shallow, small, 1- to 2-mm-diameter collections of bariumsurrounded by a radiolucent rim of edema; an appearancemirrored at endoscopy with a hemorrhagic center andedematous rim.

The majority of peptic ulcers in the stomach or duodenumare related to Helicobacter pylori infection and the remainderdue to NSAID and alcohol abuse. Most gastric ulcers arebenign. They are usually situated on the lesser curve and onthe posterior wall of the antrum and body of the stomach.Ulcers occurring on the fundus and the proximal half ofthe greater curve are more likely to be malignant. Gastriculcers related to NSAIDs and alcohol are more commonlyseen on the greater curve of the antrum. Gastric ulcers atany location can cause major hemorrhage due to the highvascularity of the stomach wall, typically via the left gastricartery. Duodenal ulcers are virtually always benign and are 3

�Figure 2.3.1.2.2A,B. Gastric erosions. (A) Classic erosive antralgastritis most likely associated with NSAID use. (B) Small discreteulcers with evidence of recent bleeding (different patient). Thearrow indicates the pylorus.


times more frequent than gastric ulcers. The majority (95%)of duodenal ulcers occur in the duodenal bulb, 5% beingpostbulbar. The latter may raise the possibility of Zollinger-Ellison syndrome. Most bleeding duodenal ulcers are situatedin the posterior wall of the duodenal bulb, where they erodethe gastroduodenal artery.

The majority of the peptic ulcers are diagnosed byendoscopy but do exhibit classic appearances on double-contrast barium studies. The appearance depends on whetherthe ulcer is seen in profile or en face. In profile, the classicfeature of a benign ulcer is the sign of penetration (i.e., theulcer crater projects through the wall of the stomach). It maydemonstrate a thin lucent line representing intact mucosa(Hampton line) or edema around the margin may causethe so-called ulcer collar. Sometimes, the edema may be soprominent that it results in an ulcer mound that projects intothe lumen of the stomach. Seen en face, the ulcer is demon-strated as a collection of barium with folds radiating to it, andthese usually fade gently as they reach the edge of the ulcer.Likewise, duodenal ulcers may be seen as an ulcer craterbut also cause deformity of the duodenal cap, particularlywhen associated with scarring from healing fibrosis (Trefoildeformity).

CT is not a sensitive imaging tool for diagnosis of simplepeptic ulcer disease, but it is very useful in the diagnosisof complications such as ulcer penetration or perforation.Imaging features include thickening of the stomach/duodenalwall, luminal narrowing, and infiltration of surrounding fator organs such as pancreas. CT is the best test for diagnosisof free air in the abdomen (duodenal and antral ulcers)or in the lesser sac (ulcers of the posterior body of thestomach).

2.3.1.2.3 Tumors of the Upper Gastrointestinal Tract Grossbleeding is unusual from tumors of esophagus, stomach, orsmall bowel, but occult upper GI hemorrhage resulting inanemia is common. Significant bleeding occasionally compli-cates gastric tumors, particularly ulcerated gastrointestinalstromal tumors (GISTs).

2.3 Bleeding 89

Gastrointestinal stromal tumor is a submucosalmesenchymal tumor that originates from smooth musclecells. It can occur anywhere in the GI tract, the stomachbeing the most common site. At barium studies, it appearsas a rounded, exophytic submucosal mass that can ulcerate.Contrast-enhanced CT demonstrates a hypervascular submu-cosal mass on arterial phase images and helps demonstratethe common exophytic element. Necrosis is a commonfeature of large lesions. On MRI, it appears as an isointensemass on T1W sequences and hypointense to isointense withhyperintense areas of necrosis on T2W sequences. Theyenhance after gadolinium administration.

Gastric carcinoma is the third most common GI malig-nancy. Diagnosis by double-contrast barium meal hasbeen largely replaced by endoscopy, which also offerssimultaneous biopsy. Staging is performed by endoscopic US(local) and CT (distant).

At double-contrast barium meal, early gastric cancerappears as either an elevated polypoid lesion, or a superficialplaque-like lesion, or as a shallow irregular ulcer. Advancedgastric cancer has different appearances in barium studies. Itmay be ulcerative, polypoid, or infiltrative. A malignant ulcerhas irregular borders with lobulated folds converging towardthe crater when viewed en face. In profile, the ulcer often hasan intraluminal location and demonstrates an abrupt acuteangle at its margin with normal mucosa. Polypoid cancershows as a smooth or lobulated filling defect, whereas theinfiltrative variety narrows the lumen and when extensiveresults in a linitis plastica appearance (5% to 15%).

CT offers good delineation of the primary tumor if wateris used as intraluminal contrast agent. CT findings includea polypoid mass with or without ulceration, focal or diffusethickening of stomach wall with loss of normal rugae, andstranding of perigastric fat. Mucinous carcinoma demon-strates areas of low attenuation and calcifications withinthe thickened gastric wall. Scirrhous carcinoma producesthickened gastric wall that shows marked enhancement ondynamic CT study.

Figure 2.3.1.2.3A. Gastrointestinal stromal tumor. Large,smooth submucosal mass with evidence of early mucosalulceration.

�Figure 2.3.1.2.3B,C. Gastrointestinal stromal tumor. Axial CECTimages of an extensive peritoneal bleeding originating fromtumor erosion (not shown) of jejunal artery. Note the contrastagent extravasation (arrow in B) indicating the origin of thebleeding.


2.3.1.3 Diagnosis of LowerGastrointestinal Bleeding

The selection of appropriate diagnostic and therapeuticstrategies is dependent on the severity and nature of thelower GI hemorrhage. These include urgent nuclear medicinestudy, angiography, and colonoscopy.

2.3.1.3.1 Nuclear Medicine Studies Nuclear medicinestudies have excellent sensitivity (more than 90%) indetecting continued acute bleeding in hemodynamicallystable patients. They can detect bleeding as low as 0.1mL/min. In addition, nuclear scintigraphy is a very usefulscreening test prior to angiography, allowing specific angio-graphic approach to the appropriate mesenteric vessel. Thedisadvantage includes low specificity especially for smallbowel lesions and lack of any therapeutic options causingpossible delays in patient’s management.

Technetium sulfur colloid is sensitive in detecting activebleeding, but significant hepatic and splenic uptake mayobscure bleeding sites in the upper abdomen. 99mTc-labeledred cell imaging is relatively time consuming but allowsrepeated imaging for up to 24 hours after injection, whichis very important in cases of intermittent bleeding. It alsoprovides better anatomic localization compared with sulfurcolloid. Red cell scintigraphy has a very high negativepredictive value (more than 90%) (i.e., a negative red cellstudy indicates that the patient has stopped bleeding). Apositive test indicates continuing bleeding, and once theanatomic site of bleeding is determined, either angiographicor surgical control can be attempted.

2.3.1.3.2 Angiography Angiography can detect bleedingwith rates as low as 0.5 mL/min. This technique requiresselective catheterization of mesenteric vessels and injectionof contrast medium. Extravasation and pooling of contrastmedium into the bowel lumen indicates active bleeding.Direct catheterization of the appropriate vessel canbe performed if bleeding site has been localized bynuclear medicine studies. The superior mesenteric arteryis catheterized and injected initially, and if this fails to

2.3 Bleeding 93

demonstrate bleeding, then the inferior mesenteric arteryand, if necessary, the celiac trunk are studied next. Angiog-raphy offers the possibility of therapeutic options suchas intraarterial infusion of vasopressin or transcatheterembolization using coils or Gelfoam (Pfizer Manufacturing,Pharmacia & Upjohn Company, Belgium).

2.3.1.3.3 Colonoscopy The role of emergency colonoscopyin patients with major ongoing lower GI hemorrhage remainscontroversial. Technical difficulties in these cases includeimpaired visualization by active bleeding or blood clotsand inability to identify anatomic sites within the colon.Furthermore, the risk of colonic perforation is higherin the emergency situation when compared with electivecolonoscopy. Colonoscopy is very useful in cases of self-limited major hemorrhage when both nuclear medicine andangiographic studies have failed to diagnose bleeding. Italso provides useful information regarding the etiology ofbleeding and allows a variety of therapeutic modalitiessuch as electrocauterization, sclerotherapy, laser photocoag-ulation, and so forth.

2.3.1.3.4 Capsule Endoscopy In this procedure, the patientswallows a small capsule that is capable of transmittingimages to an external receiver. This is proven to be particu-larly useful in demonstrating causes of obscure small bowelbleeding but must be used with caution if there is a possibilityof a small bowel stricture.

2.3.1.4 Causes of Lower Gastrointestinal Bleeding

2.3.1.4.1 Diverticular Disease Diverticular disease is themost common colonic pathology in Western society and isfound in more than 50% of individuals over the age of 60years. Diverticula can occur anywhere in the colon but aremost common in the sigmoid colon. They represent acquiredherniation of mucosa and submucosa through the muscularispropria layer of the bowel wall. Most of them are thereforefalse diverticula, containing only mucosa and submucosa.They usually measure 5 to 10 mm. Enlargement of a colonic

Figure 2.3.1.4.1A,B. Diverticular disease. (A) Double contrastbarium enema (DCBE) demonstrates a typical diverticular stricturelikely to be associated with a diverticular abscess. (B) Axial CTimage of the pelvis (3 months later) demonstrating sigmoid diver-ticulitis and confirming the presence of an intramural abscess withavid wall enhancement.

2.3 Bleeding 95

Figure 2.3.1.4.1C. Diverticular disease. Axial CECT image ofsigmoid diverticulitis (arrow) in a different patient without evidenceof stenosis or perforation.

diverticulum leads to stretching of the vasa recta located atthe dome of the lesion. Weakening and erosions into thosevessels leads to intraluminal bleeding. The hemorrhage tendsto be significant and of arterial source.

It is important to appreciate from both imaging andmanagement point of view that diverticular disease repre-sents a spectrum of stages:

• Prediverticular stage: manifested by thickening of colonicwall and the presence of immature diverticula.

• Diverticulosis stage: well-formed diverticula.• Diverticulitis: localized pericolic inflammation leading to

small abscesses due to diverticula perforation and/orstricture formation.

CT with oral/rectal and intravenous contrast medium is theimaging modality of choice, especially in the diverticulitis


phase. CT is excellent in diagnosing complications of divertic-ulitis such as perforation, intraabdominal collections, fistulae,portal vein thrombosis, and liver abscesses.

CT Features in Acute Diverticulitis

• Small colonic outpouching filled with air/contrastmedium

• Colonic wall thickening with marked enhancement• Arrowhead sign: edema at the orifice of inflamed

diverticulum• Stranding of the pericolic fat, fascial thickening• Pericolic changes such as abscess and/or sinus

formation, colovesical fistulas• Free intraabdominal air and/or fluid• Thrombus within the superior mesenteric/portal vein• Liver abscesses

Double-contrast barium enema is a traditional imagingtest. In diverticulosis stage, it clearly shows multiple diver-ticula as flask-like protrusions with broad necks (in profile)or ring shadows of well-circumscribed barium collections—bowler hat sign (en face). If acute diverticulitis or perforationis suspected, water-soluble contrast medium is used. Findingsinclude:

• Marked thickening and distortion of haustral folds.• Focal area of asymmetric narrowing of the bowel lumen

caused by intramural inflammation and mucosal tethering.• Longitudinal intramural fistulous tracts (double tracking).• Fistulas to bladder, vagina, or small bowel.• Pericolonic abscesses.• Strictures, especially in the sigmoid colon. These can

be difficult to distinguish from malignant strictures andsometimes cause large bowel obstruction.

There is little place for plain radiography, apart fromdemonstrating complications such as perforation and big

2.3 Bleeding 97

diverticular abscesses. In those cases, plain abdominal X-raycan demonstrate signs of pneumoperitoneum or mottled gascollection outside the bowel, more commonly around thesigmoid in cases of abscess formation. Air within the bladderis seen with colovesical fistulas.

2.3.1.4.2 Colorectal Carcinoma Colorectal cancer is themost common malignancy of the GI tract and the thirdmost common cancer overall. The majority (65%) occur inrectum and sigmoid colon and 98% are adenocarcinomas onhistopathology. Colorectal neoplasms account for approxi-mately 5% of significant lower GI bleeding. Double-contrastbarium enema is an excellent imaging modality for thediagnosis of colorectal cancer but is being supplanted byCT colonography (CTC). In this procedure, the colon iscleansed as for a barium enema or colonoscopy and it is thendistended with air prior to imaging. The images can eitherbe viewed in two-dimensional format or reconstructed intothree-dimensional virtual imaging format, or “fly through.”This is a particularly sensitive test for demonstrating adeno-matous polyps that are the precursor for colorectal cancer,and it rivals optical colonoscopy in their detection. Frankcarcinomas are demonstrated as polypoid masses, circum-ferential thickening of the bowel wall, or as a malignantstricture. Other changes include stranding of the pericolicfat, tumor extension through the bowel wall or into adjacentorgans, lymphadenopathy, and liver metastasis.

Barium enema if performed shows colorectal cancer aseither an anular or polypoid lesion. Annular or apple corelesions are usually found in the sigmoid colon. They appearas circumferential narrowing of the bowel with shoulderingand mucosal destruction. They also can result in large bowelobstruction. Polypoid lesions are usually large and are morecommonly found in rectum or cecum, shown as large fillingdefects.

MR has a particular role in the local staging of rectalcancers and their relationships to the mesorectal fascia.This is relevant to the need or otherwise for neoadjuvanttreatment.

Figure 2.3.1.4.2A,B. Colorectal carcinoma. (A) Contrast enemademonstrates an apple core lesion (arrows) in the rectosigmoidjunction in keeping with a carcinoma. (B) CECT confirms thepresence of the tumor (arrows) and shows a mild degree of distallarge bowel obstruction and ascites.

2.3 Bleeding 99

Figure 2.3.1.4.2C. Colorectal carcinoma. Sagittal T2-weighted MRIimage of rectal cancer (arrows). The presence of negative contrastagent (arrowheads) in the rectal lumen increases the accuracy oflocal staging.

2.3.1.4.3 Inflammatory Bowel Disease Low GI bleedingtypically occurs with ulcerative colitis (UC), but sometimesileocolic Crohn’s disease can present with profuse rectalbleeding due to arterial perforation.

Ulcerative colitis is a chronic diffuse inflammatory diseasethat involves the colorectal mucosa. Inflammation is limitedto mucosa and submucosa, whereas in Crohn’s disease, thereis transmural involvement. It usually begins in the rectumand may progress proximally to involve the whole colon. In30% of the patients, there is involvement of the terminalileum (backwash ileitis). Patients with ulcerative colitis havean increased risk of developing colorectal cancer, especially

Figure 2.3.1.4.3A,B. (A) Ulcerative colitis. DCBE demonstrates anahaustral colon with fine granular background - typical appearancesof ulcerative colitis. Also note the gaping ileocecal valve (proneimage). (B) Crohn’s disease. DCBE demonstrates typical appear-ances of Crohn’s disease with discrete asymmetrical ulceration andskip lesions.

Figure 2.3.1.4.3C,D. Crohn’s disease. (C) Axial CECT of a complexileal-cecal fistula with thickening and increased enhancement of theileal wall (arrows). (D) Coronal reformatted image demonstratingthe complex fistula (arrows) and thickened ileal wall (arrowheads).


in the case of pancolitis where 75% of the patients developcolorectal cancer.

Double-contrast barium enema is an excellent diagnostictest. Imaging findings depend on the phase of the disease.

Barium Enema Findingsin Ulcerative Colitis

Acute phase

• Fine granular pattern of colonic mucosa• Collar button ulcers• Edematous, thickened haustra• Inflammatory pseudopolyps• Narrowing of the colorectal lumen

Chronic phase

• Rigidity and symmetric narrowing of the coloniclumen giving the appearances of lead-pipe colon

• Loss of haustrations and shortening of the colon• Inflammation of the terminal ileum (backwash ileitis)• Widening of the presacral space more than 1.5 cm• Benign colonic strictures

CT features of UC are nonspecific and can be verydifficult to differentiate from other colitides, especiallyCrohn’s disease, based on imaging features alone. CT demon-strates narrowing of the large bowel lumen caused bydiffuse, symmetrical thickening of colonic wall, which isless marked than in Crohn’s disease. It shows widening ofthe presacral space due to proliferation of perirectal fat.Contrast-enhanced CT demonstrates the target or halo sign,which is the same as that in Crohn’s disease. Other featuresinclude enhancement of inflammatory pseudopolyps andstranding of the pericolic fat.

Crohn’s disease is a chronic granulomatous inflammatorybowel disease. It can occur anywhere in the bowel from

2.3 Bleeding 103

the mouth to the anus but most frequently affects theterminal ileum and proximal large bowel. Barium follow-through/enteroclysis and CT are very good in the diagnosisof the disease and its complications, and MRI is sensitive indetecting fistulas and sinuses that can be difficult to appre-ciate on other imaging modalities.

Barium Studies Findingsin Crohn’s Disease

• Skip lesions: affected and normal intervening areas• Asymmetrical thickening of the bowel all due to a

combination of inflammation and fibrosis• Aphthoid ulcers: punctate barium collections

surrounded by a halo• Fissuring ulcers• Cobblestone pattern: combination of longitudinal

and transverse ulcers• Sacculations on the antimesenteric side of the bowel• Inflammatory pseudopolyps• Luminal narrowing and multiple strictures especially

involving terminal ileum (string sign)• Sinus tracts, fistulas, and anorectal lesions

CT findings depend on the stage of the disease. In theacute stage, there is asymmetrical bowel wall thickeninggreater than 1 cm. A similar degree of thickening may beseen in pseudomembranous colitis. The target or double-halo sign on CECT is produced by intense enhancement ofinner mucosa and outer muscularis propria layers, whereasedematous thickened submucosa is of low attenuation. Inthe chronic stage, there is luminal narrowing and reducedattenuation of thickened bowel wall indicating irreversibletransmural fibrosis. CT can elegantly demonstrate mesen-teric changes such as stranding of the mesenteric fat and low-volume mesenteric lymphadenopathy. CT is also useful inthe diagnosis of disease complications such as abscesses andfistulas.


MRI examination using T2W fat-suppressed imaging orT1W imaging with intravenous Gd-DTPA are excellentfor detecting and mapping fistulas, sinuses, and abscessesespecially in perianal Crohn’s disease. Transrectal US can beuseful particularly in the evaluation of the anal sphincter incases of anal involvement.

2.3.1.4.4 Meckel’s Diverticulum Meckel’s diverticulum is acongenital true diverticulum of the ileum. It occurs in theantimesenteric border of the distal ileum, approximately 60cm proximal to the ileocecal valve. Meckel’s diverticulumusually contains ileal mucosa, but it can contain ectopictissue, such as gastric or pancreatic mucosa, in up to 50%.Bleeding is rare, but when it occurs, it is associated with thepresence of gastric mucosa. Hemorrhage is usually seen inchildren and is very rare in young adults.

Angiography is the best imaging test in setting of acutehemorrhage. It shows extravasation of contrast medium intothe diverticulum and elegantly demonstrates the persistentvitello-intestinal artery as a long, nonbranching vessel arisingfrom a distal ileal artery. Scintigraphy using 99mTc pertech-netate is a well-recognized technique for identifying aMeckel’s diverticulum that contains ectopic gastric mucosa.The area of ectopic uptake is seen within 5 to 10 minutes ofradionuclide injection as an area of increase tracer uptakein the lower abdomen, usually on the right side. The overalldiagnostic accuracy is low as the test is positive only in thosediverticula that contain ectopic gastric mucosa. Small bowelenema (enteroclysis) may be performed when the diagnosisof Meckel’s diverticulum is suspected. It is a more reliabletechnique than barium follow-through. The diverticulumappears as a blind-ending sac arising from the antimesentericborder of the distal ileum. Occasionally, the diverticulum mayinvert appearing as a filling defect, which may sometimesbecome the leading point of an intussusception.

2.3.1.4.5 Angiodysplasia Angiodysplasia represents vas-cular ectasia in microcirculation of the mucous and thesubmucous layers of the bowel and occurs primarily in

2.3 Bleeding 105

Figure 2.3.1.4.4A. Meckel’s diverticulum. Barium follow throughexamination showing a blind ending sac (arrow) arising from theantimesenteric border of distal ileum. (Continued)

the ascending colon and cecum in middle-age and elderlypatients. It is the most common cause of occult lowerGI hemorrhage, but massive bleeding is very uncommon.Angiography is the imaging test of choice with excellentresults when performed during a bleeding episode. It


Figure 2.3.1.4.4B. (Continued) Meckel’s diverticulum. Angiogramin a different patient shows persistent vitello-intestinal artery(arrow) as a long nonbranching vessel arising from a distal ilealartery.

demonstrates one or more tiny lakes of contrast medium onthe antimesenteric border of the bowel. In addition, early-filling veins may be seen draining the abnormal area.

2.3.2 Hematuria

Hematuria can be the presenting symptom of a variety ofrenal tract pathologies including stone disease, infection,neoplasms, and trauma. Diagnostic imaging of stone diseaseand transitional cell carcinoma have been discussed in detailin Section 2.1.2.9, and imaging of renal trauma will be

Figure 2.3.2A,B. Renal cell carcinoma. (A) CECT showing aheterogeneously enhancing mass (arrows) originating from themidportion of the right kidney in keeping with a renal cellcarcinoma. (B) Axial T1-weighted image of the arterial phase ofa contrast-enhanced MRI (different patient) showing a right-sidedRCC (arrow) as strongly enhancing mass.


discussed in Section 2.5.2. A general view of the bestdiagnostic approach in patients with hematuria is given inthis section. Imaging features of renal cell carcinoma are alsodescribed.

A combination of US and cystoscopy remains the bestscreening test for hematuria. US is more sensitive than IVUin demonstrating small renal masses situated outside thecollecting system. A hematuria service, with early clinicalexamination, urine cytology testing, and US, is frequentlyprovided for painless hematuria in many centers. IVUprovides good anatomic definition of the kidneys and, tosome extent, an indication of their function. It is especiallysensitive in the detection of small endothelial lesions. CT isexcellent for diagnosis and staging of renal cell carcinoma.

Renal cell carcinoma (RCC) is the most common primaryrenal tumor. Gross hematuria is the most common presentingsymptom (60%). However, more than 50% of RCCs areincidentally found on CT, US, or MRI of the abdomen. USdemonstrates a hyperechoic, hypoechoic, or in the majorityof cases an isoechoic mass. Cystic RCCs typically havemultiple thickened septae and nodular solid components.Color Doppler US is useful in detecting tumor thrombusextension to the renal vein and IVC.

At CT and on unenhanced images, RCC appears as asoft tissue mass that contains calcifications in up to 30%of the cases. Multiphase CT imaging is ideal for stagingand preoperative planning of RCC. Most RCCs are hyper-vascular on contrast-enhanced CT images. They are bestseen on nephrographic phase (renal enhancement at capillarylevel) images, whereas small intrarenal RCC can be missedon corticomedullary phase (enhancing renal cortex withlimited medullary enhancement). Contrast-enhanced CT isvery accurate for detecting tumor extension to the IVC andrenal vein, as well as distant metastasis such as liver, adrenal,lung, bone, and so forth. Three-dimensional CT recon-struction with volume rendering and maximum projectiontechniques are excellent for preoperative staging, and MRIcan provide additional information on vascular involvementif required.

2.3 Bleeding 109

Proposed Algorithm for Diagnostic Workup of PainlessHematuria

US + Cystoscopy

Normal Abnormal

Persistingbleeding

Retrogradeureterogram for

upper tracttransitional

cell carcinoma(TCC)

Renal tumour Bladder tumour

CT/MRI

Biopsy if atypicalappearances

CT staging


1. Chen CY, Wu DC, Kang WY, Hsu JS. Staging of gastriccancer with 16 channel-MDCT. Abdom Imaging 2006;31:514–520.

2. Low VHS. Diagnosis of gastric carcinoma: sensitivity of double-contrast barium studies. AJR 1994;162:329–334.

3. Miettinen M, El-Rifai W, Sobin L, Lasota J. Evaluation ofmalignancy and prognosis of gastrointestinal stromal tumours: areview. Hum Pathol 2002;33:478–483.

4. Howarth DM. The role of nuclear medicine in the detectionof acute gastrointestinal bleeding. Semin Nucl Med 2006;36(2):133–146.

5. Browder W, Cerise EJ, Litwin MS. Impact of emergency angiog-raphy in massive lower gastrointestinal bleeding. Ann Surg1986;204:530.


6. Gore RM, Miller FH, Pereles FS, Yaghmai V, Berlin JW. HelicalCT in the evaluation of the acute abdomen. AJR 2000;174:901–913.

2.4 Jaundice

Jaundice, a yellow pigmentation of the skin, mucousmembranes, and sclera, results from excess circulatingbilirubin. It is usually described as prehepatic, hepatic, orposthepatic but only the latter, essentially mechanical biliaryobstruction is amenable to surgical treatment, and this willbe discussed.

2.4.1 Radiologic Evaluation of MechanicalBiliary Obstruction

The two major causes of bile duct obstruction are biliarystones and malignant tumors. Stone disease is the mostcommon followed by carcinoma of the head of thepancreas. Other tumors include ampullary tumors, cholan-giocarcinoma, gallbladder carcinoma, and porta hepatislymphadenopathy. Benign biliary strictures resulting fromacute pancreatitis may also cause biliary obstruction, as mayischemia.

The combination of clinical assessment and radiologicexamination provides an accurate diagnosis of the cause ofposthepatic jaundice in 98% of patients. Plain abdominalradiographs are usually unhelpful in the assessment ofpatients presenting with jaundice. They may show calcifiedbiliary stones in 10% of the patients, and pancreatic areacalcification is suggestive of chronic pancreatitis.

The diagnosis of extrahepatic and/or intrahepatic bile ductdilatation is a crucial step in the evaluation of the jaundicedpatient. US is used as the primary imaging technique todiagnose the presence of duct dilatation and distinguishbetween obstructive and nonobstructive jaundice. Dilatedintrahepatic bile ducts appear as branching hypoechoic struc-tures radiating from the porta hepatis, paralleling the portal

2.4 Jaundice 111

vein and hepatic arterial branches but with no flow within.They are often detected first in the left lobe of the liver.US can define the site and cause of biliary obstruction inonly 30% of cases as the lower common bile duct is oftenobscured by overlying bowel gas. Where US is equivocal forthe presence of bile duct dilatation or is unable to identify theunderlying etiology, magnetic resonance cholangiopancre-atography (MRCP) is used as this is unaffected by bowel gas.

In a patient where biliary obstruction has been diagnosedby US, and gallstones are demonstrated convincingly asthe cause, endoscopic retrograde cholangiopancreatography(ERCP) should be the next investigation. It can reliablydemonstrate the dilated biliary system, confirm the presenceof calculi, and allow their extraction after sphincterotomy.

Where the initial investigations indicate biliary ductobstruction due to a likely malignant cause, the idealnext step is to stage the tumor in order to assess theoperability. This is best performed with CECT, prior toany drainage procedure, allowing demonstration of anobstructing mass and staging-related information such aslocal nodal enlargement and vascular invasion. Additionalinformation can be provided using both MRI, endoscopicultrasound, and ERCP where appropriate. At ERCP, plasticor self-expandable metal stents can also be placed to relievethe jaundice.

Percutaneous transhepatic cholangiography (PTC) is lessfrequently used in the assessment of obstructive jaundice butis valuable where palliative drainage is required and whereERCP has failed. Typically, this is in patients with extensivehilar malignancy, benign biliary strictures, or after gastro-duodenal surgery.

Nuclear medicine studies using 99mTc-labeledN-substituted iminodiacetic acid compounds (99mTc-HIDA)have no role in imaging of obstructive jaundice because ofimpaired bilirubin excretion but are useful in the evaluationof low-grade obstruction, after bile duct surgery, and soforth.


Suggested Algorithm in Diagnosis of ObstructiveJaundice

Abnormal LiverFunction Tests

US

Dilated Ducts

EquivocalNo causeidentified

Normal Ducts

Stop? non surgical

jaundice

DefiniteStone

DefiniteTumour

MRCP Staging CT

Stone Normal Tumour

Stone ERCP + StentInsertion

ERCP + Stone extraction+/– Sphincterectomy

2.4.1.1 Biliary Stones

Gallstones are present in approximately 15% of the adultpopulation in the United Kingdom. There are three commontypes of gallstones: cholesterol, pigmented, and mixed stones.

Figure 2.4.1A,B. (A) Gallbladder stones. US of the gallbladderdemonstrating two echogenic foci within the gallbladder repre-senting gallbladder stones. (B) Common bile duct stones. MRCPimage demonstrating a well-defined low-signal-intensity fillingdefect within the common bile duct representing a stone.


US is more than 95% accurate in the diagnosis of gallstonesin the gallbladder. They appear as one or more hypere-choic foci with related acoustic shadowing. They changeposition with change in patient position. US can also reliablyassess the presence of associated inflammatory changes inthe gallbladder.

Approximately 15% of patients with gallstones have stoneswithin the bile ducts that may appear as hyperechoic fociwithin the common bile duct, which is usually dilated. Thenormal range of US measurements for the diameter of thecommon hepatic duct is commonly accepted as up to 6 mm,unless there has been a cholecystectomy in which case 10 mmis considered the upper limit of normal. The bile duct shouldbe measured where the right main hepatic artery crossesthe common hepatic duct. The sensitivity of US in detectingcholedocholithiasis is poor, and compared with ERCP, US isonly 20% to 30% accurate in the diagnosis of the commonbile duct calculi. This is due to several factors includingnormal-caliber ducts and obscuring of ducts by overlyingbowel gas. MRCP is much more accurate, and endoscopicUS can improve accuracy further for detecting small distalcommon bile duct stones.

ERCP is the next step if US confirms bile duct stonesor if there is a strong clinical suspicion of duct stones butequivocal US findings. ERCP has the major advantage ofendoscopic sphincterotomy and stone removal, which does notnecessitate any further treatment in the elderly population,whereas younger patients are referred for subsequent chole-cystectomy. If there is doubt about the diagnosis MRCP is nextindicated as a noninvasive diagnostic test. ERCP should bereserved in most cases for its therapeutic potential.

2.4.1.2 Carcinoma of the Head of the Pancreas

Ductal adenocarcinoma of the pancreatic head is the mostcommon malignant cause of obstructive jaundice. US showsa dilated common bile duct with abrupt termination at thelevel of the pancreatic head. It may demonstrate a hypoe-choic mass at the head of the pancreas as well as locallymphadenopathy and liver metastasis. It is not a sensitivetechnique for detecting small lesions.

2.4 Jaundice 115

Figure 2.4.1. Carcinoma of the head of the pancreas. Arterialphase CECT of the abdomen showing a low-attenuation lesion(arrow) within the normal enhancing pancreatic head representinga pancreatic carcinoma.

CECT, as described in detail in Section 2.2.1.3, is thetechnique of choice for both diagnosis and staging of thedisease. The tumor appears as a low-attenuation lesion withinthe head of normal avidly enhancing pancreas (best seenin arterial and pancreatic phases). Local tumor extensioninto porta hepatis structures such as the portal vein andcontiguous invasion into the adjacent duodenum, stomach,and mesentery can be demonstrated.

ERCP demonstrates significant dilation of common bileduct with irregular distal rat-tail stricture and prestenoticdilatation. As the majority of the cases are inoperable, it isusually the practice to place a bile duct stent for palliativepurposes.

2.4.1.3 Tumors of the Biliary Tract

These include cholangiocarcinoma, ampullary carcinoma,and carcinoma of the gallbladder.


Cholangiocarcinoma is a malignant tumor that arises fromthe epithelium of intra- or extrahepatic bile ducts. It is thesecond most common primary malignant liver tumor afterhepatocellular carcinoma. It may arise from any part of thebiliary tree, but a specific subtype involving the confluence ofright and left hepatic ducts is referred to as a Klatskin tumor.Imaging is often challenging, as the tumor volume may besmall, and best achieved by a combination of techniques suchas CECT, MRI, and if needed ERCP/PTC.

US may show a heterogeneous, hypoechoic mass withintrahepatic duct dilatation or dilatation of both intra- andextrahepatic ducts in common bile duct lesions. CECT withthree phases of enhancement—arterial, portal, and delayedphase—is the best imaging test with a very good sensitivityespecially for large lesions. Gadolinium-enhanced T1W MRIand multislice CECT are probably equivalent for detectingsmall hilar tumors, as well as intrahepatic disease extensionand periductal tumor infiltration.

CT findings in cholangiocarcinoma

Nonenhanced CT

• Low attenuation single/multiple lesions at theperiphery, or central at the confluence of the ductalsystem, or at the level of common bile duct withintrahepatic bile duct dilatation

Arterial phase (at 35 seconds postinjection)

• Early rim-enhancement with heterogeneous centralenhancement of the lesion

Portal phase (at 70 seconds postinjection)

• Less marked enhancement of the lesion

Delayed phase (at 10 minutes postinjection)

• Persistent enhancing tumor (more than the adjacentliver) due to fibrous stroma

2.4 Jaundice 117

ERCP is a valuable imaging technique permittingdiagnostic biopsy and palliative intervention procedures.ERCP findings include:

• Multiple long concentric strictures of intrahepatic ductswith associated diffuse prestenotic dilatation

• Ductal wall irregularity• Hilar strictures with associated proximal intrahepatic bile

duct dilatation in Klatskin tumors• Intraductal lobulated filling defect in common bile duct

tumors

In the event of a failed ERCP, PTC may be performed.Ampullary carcinoma is a malignant tumor arising from theampulla of Vater. CECT with duodenal distension with wateris the best imaging modality for diagnosis and staging ofthe disease. It demonstrates a hypodense, lobulated softtissue mass at the ampulla. There is also dilatation ofboth common bile duct and pancreatic duct (the double-duct sign). ERCP shows intra- and extrahepatic bile ductdilatation, and dilated common duct coming to an abruptend often with significant shouldering, suggestive of malig-nancy. Concomitant biopsies can also be taken at the timeof ERCP as the ampulla itself frequently appears abnormal,although frequently much of the tumor is submucosal. Ongadolinium-enhanced T1W MRI, adenocarcinoma of theampulla appears as a hypointense lesion compared with high-signal normal enhancing pancreatic tissue. MRCP will showsimilar appearances to ERCP.

Gallbladder carcinoma it is the fifth most common GImalignancy. It usually presents as a large soft tissue massinfiltrating the gallbladder fossa and carries a very poorprognosis. Plain abdominal radiograph is often noncontrib-utory, though it may show presence of calcified gallstonesand porcelain gallbladder, both predisposing conditions forgallbladder carcinoma. US findings include a hypoechoicmass infiltrating the gallbladder fossa, irregular diffuse thick-ening of the gallbladder wall, echogenic mucosal polypoidmass larger than 1 cm, gallstones, and occasionally a calcifiedporcelain gallbladder wall. CECT demonstrates a hypovas-cular mass infiltrating the gallbladder fossa with presence


of gallstones or porcelain gallbladder. It often shows tumorextension into the adjacent liver and porta hepatis. MRI israrely performed in practice as a combination of US and CTusually provides an accurate diagnosis in most patients.


1. Han JK, Choi BI, Kim AY, et al. Cholangiocarcinoma: pictorialessay of CT and cholangiographic findings. Radiographics2002;22:173–187.

2. Talamini MA, Moesinger RC, Pitt HA, et al. Adenocarcinomaof the ampulla of Vater. Ann Surg 1997;225:590–600.

3. Levy AD, Murakata LA, Rohrmann CA Jr. Gallbladdercarcinoma: radiologic-pathologic correlation. Radiographics2001;21:295–314.

4. Ichikawa T, Erturk SM, Sou H, et al. MDCT of pancreatic adeno-carcinoma: optimal imaging phases and multiplanar reformattedimaging. AJR Am J Roentgenol 2006;187(6):1513–1520.

5. Slattery JM, Sahani DV. What is the current state-of-the-artimaging for detection and staging of cholangiocarcinoma? Oncol-ogist 2006;11(8):913–922.

2.5 Trauma

Imaging plays a crucial role in the diagnosis and managementof patients with trauma with CT the investigation of choice.New-generation multislice CT machines provide a very fastand robust data acquisition, completing examinations in a fewminutes, which is very important in critically ill patients. Thepossibility of multiplanar reconstruction is helpful in planningcomplicated surgical interventions in patients with multiorgantrauma, particularly skeletal. It goes without saying that anearly competent clinical assessment is important to ensure thatimaging studies cover all the relevant body organs at risk.

2.5.1 Chest Trauma

Major chest trauma rarely occurs in isolation and isusually part of polytrauma. Head injury, fractures of the

Figure 2.5.1A,B. Chest trauma. CT of the chest at (A) lungand (B) bone windows showing significant pneumomediastinum,pneumopericardium, as well as extensive surgical emphysema withinthe soft tissues of the anterior thoracic wall. Note posterior left riband vertebral body fractures.


vertebral column and extremities, and abdominal and pelvictrauma are all common associated injuries. One or severalthoracic structures or organs can be damaged due to bluntor penetrating chest trauma. This can lead to thoraciccage fractures, pneumothorax and hemothorax, pulmonarycontusion, diaphragmatic rupture, pneumomediastinum, andaortic dissection/rupture. Although plain chest radiographis usually the first imaging performed in a patient withsuspected chest trauma, most patients will proceed to CT.

Plain chest radiograph will demonstrate only 50% of ribfractures. Extensive views looking for subtle rib fractures arenot indicated in theacutesituation.Theydonotalterapatient’smanagement as they are almost always treated conservatively.It is more important to detect associated injuries and complica-tions such as pneumothorax or pulmonary contusions. Imagingfindings in pneumothorax are described in Section 2.1.1.1.Lung contusion occurs in the majority of cases of blunt chesttrauma. Contusions appear as areas of peripheral consoli-dation, usually adjacent to the ribs or spine. Changes on thechest radiograph appear within 6 hours of trauma and persistfor up to a week. Nonresolving or progressing areas of consol-idations should raise the suspicion of adult respiratory distresssyndrome (ARDS) or fat embolism.

Fractures of the upper three ribs imply severe trauma thatmay have resulted in damage to the great vessels, brachialplexus, spinal or major airways. Fractures of the lowerthree ribs raise suspicion for associated injuries to spleen,liver, and kidneys, and further imaging of the abdomenshould be performed. In children, rib fractures are rare asaccidental injuries, and their presence should alert thoseresponsible for the management of the patient to nonac-cidental injury. Sternal fractures occur less frequently thanrib fractures but they carry a relatively high mortality dueto associated mediastinal injuries. Lateral sternal views canreliably diagnose sternal fractures, and CT can elegantlydemonstrate associated injuries. Thoracic spine fractures areoften overlooked on the initial assessment especially if thereare no neurologic signs. CT demonstrates the presence ofthe fracture as well as other features such as paraspinalhematoma, spinal cord contusion, and so forth.

2.5 Trauma 121

Hemothorax is frequently present in patients with chesttrauma. It usually produces a meniscus sign on a conven-tional erect chest radiograph (CXR). However, in traumapatients, it is likely that the CXR is taken in a supineposition and therefore the blood tracks posterior to the lungsproducing a diffuse increased opacification of the affectedhemithorax rather than classic meniscus sign. If CXR findingsare equivocal, then CT is indicated.

Pneumomediastinum is usually caused by tracheobronchialor esophageal ruptures. The CXR appearances are of verticallucencies that outline mediastinal structures, especially onthe left side, and often extend into the neck and/or chestwall. These features are better appreciated on a lateralCXR. CT is more sensitive than plain radiography in demon-strating the presence and extent of the pneumomediastinum.Bronchial tears are uncommon, and the majority occur inthe main stem bronchus. They are usually associated withother extensive injuries such as fractures of the upper ribs,sternum, and thoracic spine. CXR demonstrates the presenceof pneumothorax, pneumomediastinum, and the fallen lungsign with complete rupture. CT with coronal reconstructionis more sensitive in locating the site of the tear and demon-strating associated injuries.

Traumatic aortic rupture due to rapid deceleration atimpact causes 15% to 20% of road traffic accident deaths.The majority of those surviving an aortic rupture haveruptures at the isthmus, just distal to the origin of the leftsubclavian artery where the aorta is most fixed. The initialradiologic evaluation is likely to be a CXR, which will beabnormal in 70% of the patients. Aortic rupture is a surgicalemergency that requires prompt diagnosis and surgical repairin virtually all cases.

Plain Chest Radiographs Findingsin Aortic Rupture

• Widening of the superior mediastinum (more than8 cm or more than 25% of thoracic width)


• Loss of definition of the aortic knuckle• Depression of the left main bronchus• Displacement of the trachea and the nasogastric tube

to the right• Left apical pleural cap and left pleural effusion• Associated fractures of the upper three ribs

CT is the next imaging test performed in suspected aorticrupture if the patient is hemodynamically stable. It elegantlydemonstrates direct signs of aortic rupture such as intimalflap, irregularity of the aortic contour, and pseudoaneurysms,as well as indirect signs of hemomediastinum. It is veryimportant to obtain unenhanced images first in order toconfirm the presence of fresh blood. Reformatted CT imageshave a very high sensitivity and specificity for diagnosingaortic rupture; however, an unexplained hemomediastinummay require urgent catheter angiography

Diaphragmatic rupture occurs in less than 5% of patientswith significant blunt thoracoabdominal trauma. Tears areusually at least 10 cm long, radially oriented, and usuallyoccur at the weakest part of the diaphragm—the posterioraspect of the musculo-tendinous junction. Left- and right-sided tears occur with equal frequencies but left-sided onesare diagnosed easier than the right-sided tears, the majorityof which are missed. This is due to the fact that liver herni-ation through a right-sided tear retains the smooth contourof the hemidiaphragm, which is interpreted mistakenly asnormal on a CXR. Prompt diagnosis of diaphragmaticrupture is very important because surgical repair of the tearis mandatory, as they do not heal spontaneously.

As noted, the CXR is insensitive in the diagnosis ofdiaphragmatic rupture, being abnormal in less than 50% ofthe cases. Radiographic findings may include:

• Elevation of the hemidiaphragm (comparison with oldfilms is very important)

• Loss of the diaphragmatic contour

2.5 Trauma 123

• Contralateral mediastinal shift• Presence of hollow viscera within the thorax• Coiled nasogastric tube within the left hemithorax

CT is the best available technique, though it is sometimesdifficult to visualize the dome of the diaphragm as it usuallylies tangential to the axial plane. Multislice CT with itsability to produce coronal and sagittal reformatted imageshas significantly improved the sensitivity and specificity ofCT. Features of diaphragmatic rupture on CT include inter-ruption of normal diaphragmatic contour, and herniation ofthe abdominal contents within the chest. On the left side,this results in the collar sign (constriction of the stomachas it passes through the tear into the chest) and on theright side the cottage loaf sign with the liver herniatingthrough the diaphragm. US is very good in visualizing thediaphragm especially if outlined by fluid and can reliablydiagnose tears. The examination is difficult if the patient isvery tender or if there are complications such as extensivesurgical emphysema, pneumothorax, and so forth, which willimpair visualization of the diaphragm. These factors togetherwith its operator dependence limit the role of US in routineimaging of the diaphragmatic rupture. MRI is excellent indetecting diaphragmatic tears, although its use in practice islimited because of MRI incompatibility of some life-supportdevices used in trauma patients. Direct multiplanar imagingis very important in detecting small tears. They are bestshown in T1W sequence where the diaphragm appears as alow-intensity line outlined on either sides by high-intensitymediastinal and abdominal fat.

2.5.2 Abdominal Trauma

Abdominopelvic trauma accounts for a large proportion ofmorbidity and mortality in multitrauma patients. Multiplelife-threatening injuries often coexist, requiring rapid triagewith simultaneous diagnostic and therapeutic interventions.The choice of imaging modalities depends to a large extenton local availability and expertise. In practice, CECT is the

Figure 2.5.2A,B. Liver trauma. (A) Unenhanced and (B) portalphase CECT of the abdomen demonstrating an irregular low-attenuation area in the posterior aspect of the right lobe of the liver(best appreciated on the CECT image) representing liver laceration.

2.5 Trauma 125

Figure 2.5.2C. Kidney trauma. CECT of the abdomen showinglack of perfusion in the posterior aspect of the right kidney. Notealso the presence of free perirenal fluid in this trauma patient.

most useful and quickest method. Imaging findings in liver,pancreatic, splenic, and urinary tract trauma are described inthis section.

2.5.2.1 Hepatic Trauma

The liver is the most frequently injured intraabdominalorgan. Trauma to the liver can lead to parenchymal lacer-ation, capsular rupture, intraparenchymal or subcapsularhematoma. Laceration may involve major vessels and canlead to massive hemorrhage. Imaging plays a crucial rolein hepatic trauma except when patients require immediatesurgery because of extensive life-threatening injuries. At CTexamination, initial unenhanced images are mandatory inorder to demonstrate high-attenuation fresh hemorrhage.The location of fresh clot can be a good indication of anearby site and source of bleeding. Postcontrast images arealso mandatory when organ trauma is suspected. Portal phase


images are excellent in detecting subtle lacerations of theliver, and arterial phase images should be performed toindicate hepatic artery trauma when an injury involving theporta is suspected. US can reliably demonstrate the presenceof free intraabdominal fluid, suggesting liver laceration orcapsular rupture, but is not reliable for parenchymal tears.It is a very useful technique for the follow-up of the knownlesions such as subcapsular hematomas as they resolve andfor diagnosing complications such as intraabdominal collec-tions. Angiography is only indicated in cases of continuingsignificant bleeding suggesting a vessel laceration. It reliablydemonstrates the source of bleeding and guides therapeuticprocedures such as embolization, thus avoiding open surgery.

2.5.2.2 Pancreatic Trauma

Pancreatic trauma is rare and is usually associated with othervisceral injuries, especially of the liver and duodenum. It istypically caused by significant direct impact such as from asteering wheel or a seatbelt injury resulting in the midlinecompression of the pancreas against the vertebral column.This may result in fracture of the gland or main pancreaticduct disruption, which carries a high complication rate. Thin-slice CT with fast bolus contrast injection (3 to 4 mL/s)and oral contrast medium is the best technique for imagingof pancreatic trauma. Imaging features include fluid in thelesser sac, thickening of the anterior renal fascia, strandingof the peripancreatic fat, focal enlargement of the pancreas,and intraparenchymal hematoma. CT can elegantly show afracture line through the gland and separation of fracturefragments. ERCP may be required if a pancreatic duct injuryis suspected.

2.5.2.3 Splenic Trauma

The spleen is the most common intraabdominal organ torequire surgery after injury. The current trend is towardconservative management because of increased incidenceof postsplenectomy sepsis. However, delayed rupture canoccur in this situation. CECT will show altered contour to

2.5 Trauma 127

the spleen in subcapsular hematomas and low-attenuationareas in intraparenchymal hematomas. Parenchymal lacera-tions appear as hypodense irregular lines (areas of nonen-hancement) separating more dense splenic fragments (areasof normal enhancement). Splenic fracture is seen as deeplaceration extending from the capsule to the splenic hilum.US plays little role in imaging of acute splenic trauma butis a good technique for the follow-up of patients that havebeen managed conservatively.

2.5.2.4 Renal Tract Trauma

Renal injury is seen in just fewer than 10% of patientswith blunt or penetrating abdominal trauma. The AmericanAssociation for the Surgery of Trauma (AAST) has describeda renal injury severity score that is based on surgical obser-vations. AAST injury grade varies from grade I (renalcontusion or subcapsular hematoma) to grade V (shatteredkidney with renal vascular pedicle injury). Most renal injuriesare minor (grade I and II) and are managed conservatively.The main role of imaging in renal trauma is to help indeciding whether the patient should be managed conserva-tively or surgically. CECT is the initial study of choice inrenal trauma. Nephrographic and parenchymal phases arevaluable in demonstrating perfusion, active bleeding, andextent of parenchymal injury, and excretory phase is veryuseful in assessing the integrity of the collecting system.CECT findings depend on the grade of the injury.

CECT Grading of Renal Injuries

Grade I injury

• Intraparenchymal contusion/hematoma: ill-definedarea of reduced attenuation relative to normalkidney (parenchymal phase)

• Subcapsular hematoma: round fluid collection ofrelatively high attenuation (clotted blood)


• Small linear lacerations with hematoma adjacent tothem

• Subsegmental cortical infarct: wedge-shaped low-attenuation area

Grade II injury

• Deeper laceration through cortex extending tomedulla: hypodense area in the nephrographic phase

• Contrast medium extravasation into the perinephricspace during the excretory phase

• Segmental cortical infarct

Grade III injury

• Renal lacerations extending into collecting system,vascular injury (active arterial contrast extrava-sation)

• Cortical rim sign representing preserved capsularenhancement a reliable sign of subacute infarction

• Shattered kidney pathognomonic of renal arterythrombosis: lack of enhancement of entire injuredkidney

• Perinephric hematoma, hemoperitoneum

Grade IV injury

• Fragmentation of the kidney with large perinephrichematoma compromising renal perfusion

• Avulsion of the renal pedicle• Active bleeding and urine extravasation into the

peritoneal cavity

US has a low sensitivity and a very low negative predictivevalue for the diagnosis of renal trauma and cannot provideany functional information about the injured kidney. It is,however, a useful technique for the follow-up of posttrau-matic intrarenal or perirenal collections. Limited IVU (singleradiograph), usually taken in the operating theater (once the

2.5 Trauma 129

patient is stable) can be helpful as it allows the visualizationof both kidneys and reliably diagnoses most of the majorrenal injuries. The only role of angiography in renal trauma isto demonstrate the vascular anatomy prior to reconstructivesurgery.

2.5.2.5 Bladder Trauma

The bladder is the most commonly injured organ after bluntpelvic trauma. The presence of a full bladder increases thelikelihood of bladder injury in pelvic trauma. The spectrumof injury includes bladder contusion, interstitial injury, andintraperitoneal rupture, extraperitoneal rupture, or a combi-nation of both. Intraperitoneal rupture is caused by directtrauma to the distended bladder and usually occurs at thedome of the bladder. It accounts for 15% of bladder injuries.Extraperitoneal rupture is usually caused by bony fragmentsfrom anterior pelvic arch fractures and is located at thebase of the bladder. It accounts for 85% of significantbladder injuries. CT cystography has been shown to bevery useful especially in imaging of extraperitoneal bladderruptures as it also elegantly demonstrates multiple pelvicfractures and any other concomitant injuries. Cystographyshows contrast medium extravasation in paracolic guttersand around the bowel loops in cases of intraperitonealbladder rupture. Findings in extraperitoneal rupture includeperivesical contrast medium extravasation producing a flame-shape urinary bladder and extravasation of contrast mediuminto the perineum, anterior abdominal wall, scrotum, and soforth.


1. Dee P. The radiology of chest trauma. Radiol Clin North Am1992;30:291–306.

2. Shackleton KL, Stewart ET, Taylor AJ. Traumatic diaphrag-matic injuries: spectrum of radiographic findings. Radiographics1998;18:49–59.


3. Lubner M, Menias C, Rucker C, et al. Blood in the belly: CTfindings of hemoperitoneum. Radiographics 2007;27(1):109–125.

4. Shanmuganathan K, Mirvis SE, Boyd-Kranis R, Takada T,Scalea TM. Non-surgical management of blunt splenic injury:use of CT criteria to select patients for splenic arteriography andpotential endovascular therapy. Radiology 2000;217:75–82.

5. Kawashima A, Sandler CM, Corl FM, et al. Imaging ofrenal trauma: a comprehensive review. Radiographics 2001;21:557–574.

6. Vaccaro JP, Brody JM. CT cystography in the evaluation ofmajor bladder trauma. Radiographics 2000;20:1373–1381.

Index

AAbdomen

acute. See Abdominal painfluid collections in, 60–63free air in, 88“gasless,” 34, 51postoperative, 64septic, 60–65

Abdominal aortic aneurysm,78–82

Abdominal pain, 30–59appendicitis-related, 42–46cholecystitis-related, 46–50large bowel obstruction-

related, 34–38pancreatitis-related, 50–53pneumoperitoneum-related,

38–42pseudoobstruction (Ogilvie’s

syndrome)-related,38, 39

renal colic-related, 56–59small bowel ischemia-related,

53–56small bowel obstruction-

related, 30–34Abdominal x-rays

of abdominal aorticaneurysms, 78

for abdominal painevaluation, 30

of appendicitis, 43of cholecystitis, 48of diverticular disease, 96–97

of large bowel obstruction,34–36, 37

of pancreatitis, 50of pneumoperitoneum, 38,

39–41of pseudoobstruction

(Ogilvie’s syndrome),38, 39

of small bowel ischemia, 53of small bowel obstruction,

30–31, 32, 34of urolithiasis, 56, 58

Abscessintraabdominal

appendicular, 47diverticular, 96–97pancreatic, 53paracolic, 60, 61pericolonic, 96postoperative, 64subhepatic, 60subphrenic, 40–41, 60

pulmonary, pneumonia-related, 22

Adenocarcinoma, 75, 85Adenoma, hepatic, 68, 69, 71,

73–74Adrenal carcinoma/tumors, 71–75Ampullary carcinoma/tumors,

110, 115, 117Aneurysm, abdominal aortic,

78–82Angiodysplasia, 104–106

131

132 Index

Angiographyof angiodysplasia, 104–106computed tomography, 6,

79–80, 81, 89digital subtraction, 6of gastrointestinal

hemorrhage, 84of gastrointestinal tract

hemorrhage, 92–93of hepatic trauma, 126magnetic resonance (MRA),

6, 10, 70, 82of Meckel’s diverticulum, 104of renal tract trauma, 129of small bowel ischemia, 55X-ray-based, of abdominal

aortic aneurysm, 82Aortic dissection/rupture, 18–21,

20, 120, 121–122Aortography, of aortic

dissection/rupture, 21Appendicitis, acute, 42–45, 60Appendicoliths, 43, 44, 45, 47Appendix, gas-filled, 37–38Apple core lesions, of the

sigmoid colon, 99Arrowhead sign, 96Arteriography, 6

computed tomography, 69Aspiration

of contrast media, 3of intraabdominal fluid

collections, 61–62Atelectasis, basal pulmonary,

40–41

BBalthazar CT Severity Index, 53Barium enemas, 4

bird of prey sign on, 38of colorectal carcinoma, 97, 99of diverticular strictures, 95double-contrast

of colorectal carcinoma,97, 99

of diverticular disease, 96

of gastric carcinoma, 89–90of gastric erosions,

86–87, 88of peptic ulcers, 88of ulcerative colitis, 99,

100–102of sigmoid volvulus, 38single-contrast, of large bowel

obstruction, 36Barium studies, 3–4, 5

barium meal, 4barium swallow, 3–4of Crohn’s disease, 103of esophageal varices, 85, 86of gastrointestinal stromal

tumors (GISTs), 89Bile ducts, mechanical

obstruction of, 110–118Biliary stones. See GallstonesBiloma, 50Bird of prey sign, 38Bladder, traumatic injury to, 129Bleeding. See HemorrhageBoerhaave’s syndrome, 27–29Bowler hat sign, 96Bronchial carcinoma, as chest

pain cause, 23–27Bronchoscopy, of bronchial

carcinoma, 23–24

CCalcification

adrenal, 74aortic dissection-related, 20of gallstones, 117–118pancreatic, 50, 110

Cecumabscess formation in, 47perforation of, 35polypoid lesions of, 99volvulus of, 37–38

Chest pain, 16–29aortic dissection/rupture-

related, 18–21Boerhaave’s syndrome-

related, 27–29

Index 133

bronchial carcinoma-related,23–27

pleuritic, 16pneumonia-related, 21–23pneumothorax-related, 16–18

Chest trauma, 118–123Chest x-rays

of abdominal sepsis, 60of aortic dissection/rupture,

18–19, 20, 21, 121–122of Boerhaave’s syndrome, 29of bronchial carcinoma,

23–26, 27of chest trauma, 120, 121of diaphragmatic ruptures,

122–123of pneumonia, 21–23, 24of pneumoperitoneum, 38–39of pneumothorax, 16–18

Chilaiditi’s syndrome, 40Child abuse, as rib fracture

cause, 120Cholangiocarcinoma, 110, 115,

116–117Cholangiopancreatography

endoscopic retrograde(ERCP), 111, 114, 115,116, 117, 126

magnetic resonanceimaging as alternativeto, 10

magnetic resonance (MRCP),111, 113, 114, 117

percutaneous transhepatic(PTC), 111, 116, 117

Cholecystectomy, 114Cholecystitis, 46–50, 60Choledocholithiasis, 114Cirrhosis, 66, 69Coffee bean sign, 38Colic, renal, 5, 56–59Colitis, ulcerative, 99–103Collar sign, 123Colon

diverticula of, 93–97lead-pipe, 101

pseudoobstruction (Ogilvie’ssyndrome) of, 35, 38, 39

sigmoidapple core lesions of, 99diverticula of, 93, 95, 96volvulus of, 37, 38

Colon carcinoma, 36Colon cutoff sign, 51Colonography, computed

tomography, 97, 99Colonoscopy, 93, 99Colorectal carcinoma, 97–99Computed tomography (CT),

8–9of abdominal aortic

aneurysms, 78, 81–82for abdominal pain

evaluation, 30adrenal tumors, 71, 73of aortic dissection/

rupture, 122of appendicitis, 43, 44, 45–46of Boerhaave’s syndrome, 29of bronchial carcinoma, 23–24,

26, 27of chest trauma, 119, 120, 121of cholangiocarcinoma, 116contrast-enhanced, 71, 73–74

of abdominal aorticaneurysms, 80–81

of abdominopelvic trauma,123–124, 125, 126–128

of ampullarycarcinoma, 117

of aortic dissection, 19,20–21

of biliary ductobstruction, 111

of cholangiocarcinoma, 116of cholecystitis, 48, 49, 50of colorectal carcinoma, 98of Crohn’s disease,

102–103, 103–104of diverticular disease, 95of gallbladder carcinoma,

117–118

134 Index

Computed tomography (cont.)of gastrointestinal stromal

tumors (GISTs), 89, 91of hepatocellular

carcinoma, 69, 70of liver metastases, 70–71of liver tumors, 67–68,

69, 70of pancreatic cancer/

tumors, 75–76, 115of pancreatitis, 52, 53of renal cell carcinoma, 107of renal tract trauma,

127–128of retroperitoneal sarcoma,

77, 78of small bowel ischemia,

55, 56of small bowel obstruction,

31, 32, 33of splenic trauma, 126–127of ulcerative colitis,

102–103of diaphragmatic ruptures, 123of diverticular disease, 95–96emission (ECT), 13of gastric carcinoma, 91of hepatic trauma, 125of intraabdominal fluid

collections, 60–62as ionizing radiation source, 9of large bowel obstruction, 36of liver metastases, 70–71multislice, 9noncontrast-enhanced, 71, 73

of aortic dissection/rupture, 20–21

of cholangiocarcinoma, 116of urolithiasis, 58, 59

of pancreatic trauma, 126of peptic ulcer

complications, 88of pneumoperitoneum, 41–42of pneumothorax, 18of pseudoobstruction

(Ogilvie’ssyndrome), 38

of renal cell carcinoma,108–109

for renal colic evaluation, 5of small bowel obstruction, 34of transitional cell

carcinoma, 59of ulcerative colitis, 102

Computed tomography (CT)angiography, 6, 79–80,81, 89

Computed tomography (CT)arteriography,hepatic, 69

Computed tomography (CT)colonography, 97, 99

Computed tomographycystography, 129

Continuous diaphragmsign, 39

Contrast medium agentsgadolinium-based, 11,

68–69, 104liver-specific, 70for magnetic resonance

imaging, 11microbubble-based, 8for ultrasound studies, 8

Contrast medium studies, 3–6intravenous contrast studies,

4–6oral contrast studies, 3–4

Contusions, pulmonary, 120Coronary arteries, aortic

dissection-relatedocclusion of, 20

Cottage loaf sign, 123Crohn’s disease, 62, 99,

102–104Cross-sectional imaging,

7–12Cross-sectional studies,

7–12Cupola sign, 40Cystography, computed

tomography, 129Cystoscopy, for hematuria

diagnosis, 108

Index 135

DDiaphragm, rupture of, 120,

122–123Dieulafoy lesions, 83Diverticular disease, 60, 93–97Diverticulitis, 34, 38, 95–96Diverticulosis, 95Doges cap sign, 39Doppler effect, 8Double-diaphragm sign, 17Double-duct sign, 117Double-halo sign, 103Double tracking, 96Duodenal ulcers, 60, 88

EEchocardiography, 21Echoreflexitivity, 7Empyema, pneumonia-

related, 22Endoscopy, 83–84, 86–87, 93Enteroclysis, of Meckel’s

diverticulum, 104, 106Esophagitis, 84, 85Esophagus

barium studies of, 3–4Barrett’s, 84–85ruptures/tears of, 3, 27–29, 121varices of, 85–86

FFallen lung sign, 121Fever (pyrexia), of unknown

origin, 62–63Fistulae

aortoduodenal, 81–82colovesical, 96, 97pelvic, 62

Fluid collections, intraabdominal,60–63

Fluoroscopy, 2, 3–4Focal nodular hyperplasia

(FNH), 66, 68, 69Football sign, 40

GGallbladder

in acute cholecystitis, 47, 48perforation of, 50porcelain, 117–118

Gallbladder carcinoma, 110, 115,117–118

Gallium-67 imaging, 62–63Gallstone ileus, 34, 48Gallstones, 110, 112–114

as biliary obstructioncause, 111

calcified, 117–118as cholecystitis cause, 47cholesterol, 112mixed, 112as pancreatitis cause, 50,

52, 53pigmented, 112

Gamma cameras, 12–13Gastric carcinoma/tumors, 89–91Gastritis, acute hemorrhagic, 86Gastroduodenal erosions, 86–88Gastroesophageal reflux disease

(GERD), 84Gastrointestinal stromal tumors

(GISTs), 88–91Gastrointestinal tract

as hemorrhage site. SeeHemorrhage,gastrointestinal

perforated, 3

HHalo sign, 102–103Hampton line, 88Helicobacter pylori, 87Hemangioma, hepatic, 66, 68–69Hematoma, subcapsular, 126Hematuria, 56, 82, 106–109Hemorrhage, gastrointestinal,

82–110hematuria, 56, 82, 106–109hepatic trauma-related,

125, 126

136 Index

Hemorrhage (cont.)lower-tract, 82, 92–106upper-tract, 82–91

Hemothorax, traumatic, 120, 121Hepatitis, 69Hepatocellular carcinoma, 66,

67–68, 69–70Hernia, incarcerated, 34Hollow viscus, perforation of,

38–42Hydronephrosis, 58, 59Hydropneumothorax, 24

IIleitis, backwash, 99, 101Ileus

gallstone, 34, 48paralytic, 51, 60, 64

Imaging, principles of, 1–14. Seealso specific types ofimaging

Inferior vena cava, 74, 81Inflammatory bowel disease, 62,

99–104Intraabdominal tumors

adrenal tumors, 71–75liver tumors, 66–71pancreatic tumors, 66, 75–76retroperitoneal tumors, 77–78

Intravenous urography (IVU), 5,58, 59, 108, 128–129

Intussusception, 104Inverted V sign, 40Iodine-based contrast medium,

3, 5Ionizing radiation

computed tomography-related, 9

X-rays-related, 2Iopamidol, 5Ischemia, of the small bowel,

53–56

JJaundice, 75

definition of, 110obstructive, 110–118

KKidney, horseshoe, 81Klatskin tumors, 116, 117

LLarge bowel. See also Cecum;

Colonbarium studies of, 4obstruction of, 34–38, 96

Light bulb sign, 68–69Liposarcoma, perinephric, 78Liver, traumatic injury to,

125–126Liver tumors, 66–71Lucent liver sign, 39Lung cancer. See Bronchial

carcinomaLymphoma, of the small

bowel, 33

MMagnetic resonance angiography

(MRA), 6, 10, 70, 82Magnetic resonance cholan-

giopancreatography(MRCP), 111, 113,114, 117

Magnetic resonance imaging(MRI), 10–12

of abdominal aorticaneurysms, 82

for abdominal painevaluation, 30

of adrenal tumors, 71, 74advantages and disadvantages

of, 11, 12of ampullary carcinoma, 117of aortic dissection, 20of benign liver lesions, 68–69of biliary duct obstruction, 111of bronchial carcinoma, 27of cholangiocarcinoma, 116contrast agents for, 11of Crohn’s disease, 104of diaphragmatic rupture, 123

Index 137

of gastrointestinal stromaltumors (GISTs), 89

of hepatocellularcarcinoma, 70

of inflammatory boweldisease, 62

of liver metastases, 70–71of rectal carcinoma, 98, 99of renal cell carcinoma,

108–109of retroperitoneal sarcoma, 78

Masses, intraabdominal. SeeIntraabdominal tumors

Meckel’s diverticulum, 104,105–106

Mirizzi’s syndrome, 50Mucinous carcinoma, 91Murphy’s sign, 47, 48

NNonsteroidal anti-inflammatory

drugs, adverse gastriceffects of, 86, 87

Nuclear medicine studies, 12–13,84, 92, 111

OOgilvie’s syndrome

(pseudoobstruction),35, 38, 39

Oncocalyx, 59

PPain

abdominal. See Abdominalpain

thoracic. See Chest painPancreas, traumatic injury to, 126Pancreatic cancer/tumors, 75–76

of the head of the pancreas,110, 114–115

Pancreatitis, 50–53, 60, 110Pelvic inflammatory disease,

44, 60Peptic ulcers, 38, 84–85, 87–88

Pericardial effusions, lungcancer-related, 26, 29

Pharynx, barium studies of, 3–4Pheochromocytoma, 73Phleboliths, 58Plain radiographs. See X-ray(s)Pleural effusions, 22, 26, 29,

51, 60Pneumatocele, pneumonia-

related, 22Pneumomediastinum, 119,

120, 121Pneumonia, as chest pain cause,

21–23, 24Pneumopericardium, 119Pneumoperitoneum, 38–42, 64Pneumothorax, 16–18, 120Positron emission tomography-

computed tomography(PET-CT), 13

Positron emission tomography(PET), 13, 71, 74

[18F]fluorodeoxyglucose(FDG), 27, 71

Pregnant women, acuteappendicitis diagnosisin, 44

Pseudoobstruction (Ogilvie’ssyndrome), 35, 38, 39

Pyemia, portal, 96

RRadionuclides, 12Rectal carcinoma, 98, 99Rectosigmoid carcinoma, 34Red-cell imaging, 99mtechnetium-

labeled, 92Renal arteries, involvement in

abdominal aorticaneurysms, 78

Renal cell carcinoma, 107,108–109

Renal tract, traumatic injury to,127–129

Retroperitoneal sarcoma,77–78

138 Index

Rib fractures, 120Rigler’s sign, 40

SScintigraphy

of gastrointestinalhemorrhage, 92

iminodiacetic acid(HIDA)-based, 48,50, 111

of Meckel’s diverticulum, 104red cell-labeled, 92white cell-labeled, 62–63

Scirrhous carcinoma, 91Sentinel loop sign, 51Sepsis, abdominal, 60–65Single positron emission

computed tomography(SPECT), 13

Small bowelbarium studies of, 4ischemia of, 53–56obstruction of, 30–34, 64

Small bowel enema(enteroclysis), 104, 106

Spleen, traumatic injury to,126–127

Stents, biliary, 115Stomach, erosive lesions of, 86–88Stress syndrome, 86Strictures

biliary, 115colonic, 101diverticular, 95, 96hilar, 117

String of beads sign, 34Superior sulcus tumors, 24, 27Superior vena cava, obstruction

of, 85–86Super paramagnetic iron

oxide, 70

TTamponade, cardiac, 20Target sign, 102–103Transitional cell carcinoma, 59

Trauma, 118–130abdominopelvic, 118, 120,

123–129thoracic, 118–123

Trefoil deformity, 88

UUlcers. See also Duodenal ulcers;

Peptic ulcerscollar button, 101Crohn’s disease-related, 103

Ultrasound, 7–8for abdominal pain

evaluation, 30advantages and disadvantages

of, 7, 8of appendicitis, 43–44of biliary duct obstruction,

110–111of cholangiocarcinoma, 116of cholecystitis, 46, 50contrast agents for, 8of Crohn’s disease, 104of diaphragmatic ruptures, 123Doppler, 6, 8of gallbladder carcinoma,

117, 118of gallstones, 112–114of hematuria, 108of hepatic trauma, 126of hepatocellular carcinoma,

69, 70of intraabdominal fluid

collections, 60, 61–62of liver metastases, 70–71of liver tumors, 66, 68of pancreatic cancer/tumors,

75, 114of pancreatitis, 50of renal tract trauma, 128of splenic trauma, 127of transitional cell

carcinoma, 59Ureteric stones, 56,

58, 59Urolithiasis, 56, 58, 59

Index 139

VVarices, esophageal, 85–86Venography, 6Vertebral body fractures, 118,

119, 120Vesico-ureteric junction

calculus, 59Volvulus

cecal, 37–38sigmoid, 37, 38

WWhite-cell scanning, of

abdominal sepsis, 62–63

XX-ray(s). See also Abdominal

x-rays; Chest x-raysbasic principles of, 1–2discovery of, 15

X-ray angiography, 6X-ray contrast studies, of

pneumoperitoneum, 42X-ray swallowing studies, of

Boerhaave’s syndrome,28, 29

ZZollinger-Ellison syndrome, 88

radiology for surgeons_in_clinical_practice

Health & Medicine

interventional radiology

publication data radiology

lomas helmut ringl radiology

clinical practice foreword

evis sala alan

clinical symptoms

freeman david

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