foundations of sonography (2) chuan lu 卢 川 department of diagnostic medical imaging school of...

Foundations of Sonography (2)

Chuan Lu 卢 川Department of

Diagnostic Medical Imaging

School of Radiology

Taishan Medical University

Topics

Introduction to Scanning Techniques Orientation to Labeling and Patient Position Sonographic Terminology Ultrasound Criteria For Cyst/Complex/Solid Patient Preparation Clinical Applications of Ultrasound

Introduction to Scanning Techniques

The state of the art ultrasound demands a high degree of manual dexterity and hand-eye-coordination and ability to conceptualize two-dimensional information into a three –dimensional format.

In addition, the sonographer must possess a

thorough understanding of anatomy , physiology, instrumentation, artifact production, and transducer characteristics.

Sectional Anatomy

The sonographer must have a solid knowledge of both gross anatomy and sectional anatomy , and the normal anatomical variations that may occur in the body.

The sonographer should carefully evaluate organ and vascular relationships to the neighboring structures rather than memorizing where in the abdomen a particular structure” should “ be ( i.e., it is better to recall the location of the gallbladder as anterior to the right kidney and medial to the liver than to remember it is found 6 cm above the umbilicus)

Ultrasound equipment today is so sophisticated that it demands a much greater understanding of the physical principles of sonography to produce quality images.

The addition of Doppler techniques , color flow mapping, and three-dimensional imaging has enhanced the understanding of anatomy and physiology as it relates to blood-flow dynamics and reconstruction

The student will soon learn that the “art of scanning” cannot be acquired from reading a textbook; the one-on-one, individual “hand –on” training in a clinical atmosphere is a critical and integral part of the sonographer’s experience in producing high-quality scans.

The sonographer must be aware of the special scanning techniques , artifacts encountered , and equipment malfunctions to be able to produce consistently high-quality scans .

Ultrasound can distinguish interfaces among soft tissue structures of different acoustic densities . The strength of the echoes reflected depends on the acoustic interface and the angle at which the sound beam strikes the interface.

The sonographer must determine which ”window “ on the patient is the best to record optimal ultrasound images and which transducer will best fit into that window.

Orientation to Labeling and Patient Position

Terms Relating to Orientation

Anterior or Ventral : Structure lying toward the front of the patient

Posterior or Dorsal: Structure lying toward the back of the patient

Lateral : Structure lying away from the midline

Medical :Structure lying toward the midline Proximal :Near Distal : Away from the origin Prone : The patient lies on his or her

stomach Supine: The patient lies on his or her back

Superior ,Cranial ,Cephalad :Interchangeable terms denoting a structure closer to the patient’s head

Inferior or Caudal : Terms denoting a structure closer to the patient’s feet

Proximal :Near

Distal : Away from the origin

Anterior or Ventral : Structure lying toward the front of the patient

Posterior or Dorsal: Structure lying toward the back of the patient

Terms Relating to Orientation

Terms Relating to Labeling

The American Institute of Ultrasound in Medicine( AIUM) has established standards for labeling studies so that a sonogram done in Columbus , Ohio, can be interpreted with no misunderstanding in Baltimore, Maryland.

These standards are occasionally revised and are available on request from the ( AIUM)

One of the great features of real-time ultrasound is that structures can be visualized in their long axis, which may be oblique and not fall neatly into a sagittal or transverse plane

However, the basic principle of examining everything in at least two plane is a sound one, so suggestions for labeling an abdomen in longitudinal and transverse plane will be discussed here

Longitudinal (Sagittal )Scans

In the abdomen, the aorta and the inferior vena cava(IVC) may not follow an exact longitudinal plane, but should be imaged in their long axis if possible . Since these images also include other anatomy of interest-left lobe of liver, superior mesenteric artery, pancreas, and so forth-it suffices to label them ”ML” (midline) unless you wish to draw the sonologist’s attention to something in particular.

Longitudinal scans present the patient’s head to the left of the screen and feet to the right of the screen and use the xiphoid , umbilicus , or symphysis to denote the midline of the scan plane.

longitudinal scans (Sagital Scan)

The longitudinal scans for the abdomen and pelvis are oriented with the patient’s head toward the left of the screen and feet toward the right of the screen. This means the sonographer would be viewing the body from the right side of the patient.

Longitudinal scan

The longitudinal scans for the abdomen and pelvis are oriented with the patient’s head toward the left of the screen and feet toward the right of the screen.

Ultrasound of spleen and left kidney—Patient lying on back head to left.a. spleenb. left kidney

The longitudinal scans for the abdomen and pelvis are oriented with the patient’s head toward the left of the screen and feet toward the right of the screen. This means the sonographer would be viewing the body from the right side of the patient.

All transverse supine scans are oriented with the liver on the left of the screen ;this means the sonographer would be viewing the body from the feet up to the head (“optimistic view”)

All transverse supine scans are oriented as looking up from the feet, with the liver on the left side of the screen( right side of the patient is on the left of the screen)

Transverse ScanTransverse Scan

Transverse ScanTransverse Scan

All transverse supine scans are oriented as looking up from the feet, with the liver on the left side of the screen( right side of the patient is on the left side of the screen)

Normal pancreas seen on sonogram. Looking up from abdomen toward the head of the patient. The liver is in front of the pancreas. A vein draining the spleen is behind the pancreas.

Transverse Scans Transversely ,whether you are angling

cephalad or not, on inspiration or not ,”trans left,” ”trans right,””trans left obl,” “trans right obl” will cover most of the labeling needed in the abdomen.

All scans should be appropriately labeled for future reference. This include the patient’s name, date, and anatomic position.

Body position markers are available on many ultrasound machines and may be used in the place of written labels

Decubitus These are scans taken with the patient lying

on either side; following the traditional radiology standard, the label is for the side down. So an image of the left kidney , taken with the patient on her right side, is labeled “right lateral decubitus.”

The position of the patient should be described in relation to the scanning table( e.g., a right decubitus would mean the right side down; a left deculitus would indicate the left side down).

If the scanning plane is oblique ,the sonographer should merely state that it is an oblique view without specifying the exact degree of obliquity

Oblique Scan

Coronary scan

Real-time scans are labeled as transverse or longitudinal for a specific organ, such as the liver , gallbladder, pancreas , spleen , or uterus.

The smaller organs that can be imaged on a single plane, such as the kidney , are labeled as long-middle, -lateral ,or medial ; whereas the transverse scans are labeled as transverse –low,-middle , and high.

Sonographic Terminology

Sonographic Terminology

One of the primary responsibilities of the sonagrapher is the identification and description of normal and abnormal anatomy. The following descriptive list of key terminology will help the sonagrapher summarize the results obstained from the

Ultrasound examination

Anechoic or sonolucent-(black on screen ) (opposite of echogenic) well-defined

echgenic walls without internal echoes; this structure is fluid-filled and transmits

sound easily

Anechoic or sonolucent (black-water): Example: vascular structure (blood), distended urinary bladder, gallbladder (bile), amniotic cavity, simple cyst

Anechoic or sonolucent: Example: vascular structure, distended urinary bladder, gallbladder, amniotic cavity, simple cyst

Ultrasound of the gallbladder. The wall or lining of the gallbladder is white, the bile within the gallbladder is mostly made of water and it appears as a clear black space within the walls of the gallbladder.

Echogenic or hyperechoic-(opposite of anechoic) echo-producing structure:

reflects sound with a brighter intensity Example: gallstone, renal calyx, bone, fat,

fissures, ligaments

Hypoechoic: low –level echoes within a structure

Example: liver, renal parenchyma, spleen, pancreas, lymph nodes

Hypoechoic: low –level echoes within a structure

Example: liver, renal parenchyma, spleen, pancreas, lymph nodes

Isechoic- very close to the normal parenchyma echogenicity pattern

Example: metastatic disease

Enhancement, increased through transmission-sound that travels through an anechoic (fluid-filled) substance and is not attenuated

Homogenerous-

(opposite of heterogenerous) completely uinform in texture or composition

Example: the text of the liver, thyroid, scrotum, and myometrium are homogenerous

Homogenerous

Example: the texture of the liver, thyroid, scrotum, and myometrium are homogenerous

Homogenerous

Ultrasound of the liver. This image demonstrates the (homogenerous.) liver tissue

Inhomogenerous( hysterogeneous)-not uniform in texture or composition

Example: many tumors have characteristics of both” cystic” and solid types of patterns

Inhomogenerous( hysterogeneous)-not uniform in texture or composition Example: many tumors have characteristics of both” cystic” and solid types of patterns

Inhomogenerous( hysterogeneous)-not uniform in texture or composition Example: many tumors have characteristics of both” cystic” and solid types of patterns

Inhomegenous

homegenous

Acoustic Shadowing Shadowing-the sound beam is attenuated by a solid or calcified object. This reflection or absorption may be partial or

complete . A stone would cause a sharp shadow

posterior to its border Air bubbles in the duodenum may cause a

“dirty shadow” to occur secondary to reflection.

Acoustic Shadowing

A stone would cause a sharp shadow posterior to its border

Fluid level-interface between fluids with different acoustic characteristics. This level will change with patient position

Example: dermoid with fluid level

Ultrasound Criteria For Cyst/Complex/Solid

Ultrasound Criteria For Cyst/Solid/Complex The through transmission of the sound is either

increased, unchanged ,or decreased .An anechoic mass will show increased transmission of sound ,whereas a dermoid tumor will show decreased transmission

The characteristic of an organ or mass is said to be either anechoic , hypoechoic, isoechoic , hyperechoic ,or echogenic

Transmission is altered by whether a structure is cyst, complex ,or solid

Ultrasound Criteria For Cyst/Solid/Complex

Cyst : Anechoic, smooth, well-defined border,

increased transmission Solid : Internal echoes , irregular /regular

borders , decreased transmission Complex: Has characteristics of both cyst

and solid

Cyst : Anechoic, smooth, well-defined border, increased transmission

Cyst : Anechoic, smooth, well-defined border, increased transmission

Solid : Internal echoes , irregular /regular borders , decreased transmission

Solid : Internal echoes , irregular /regular borders , decreased transmission

Solid : Internal echoes , irregular /regular borders , decreased transmission

Solid : Internal echoes , irregular /regular borders , decreased transmission

Complex: Has characteristics of both cyst and solid

Complex: Has characteristics of both cyst and solid

Complex: Has characteristics of both cyst and solid

Ultrasound Criteria For Cyst/Complex/Solid

After the sonographer has delineated the normal landmarks and anatomic structures, careful evaluation is made for the presence of pathology. The abnormality is evaluatated by several criteria which include:

The border of the structure may be smooth and well-defined, or irregular

The texture(or parenchyma) of the structure is either homogeneous or heterogeneous;if a mass is present, it may be hypoechoic, echogenic, or isoechoic to the rest of the parenchyma

The through transmission of the sound is either increased , unchanged, or decreased, whereas a dermoid tumor will show decreased transmission

The characteristic of an organ or mass is said to be either anechoic, hypoechoic, isechoic, hyperechoic, or echogenic

Transmission is altered by whether a structure is a cyst, complex, or solid

Cyst: Smooth ,well-defined borders, anechoic, increased transmission

Complex: Has characteristics of both cyst and solid(abscess)

Solid:Irregular borders, internal echoes, decreased transmission

Patient Preparation

Patient Preparation

Gallbladder and Pancreas Scans Patients scheduled for upper abdominal scans

should ingest nothing that will make the gallbladder contract for at least 8 hours preceding the sonogram.

Water is acceptable, but often the patient is scheduled for an upper gastrointestinal series the same day.

This can be a problem if good visualization of the pancreas is required , since water in the stomach is often crucial to the ultrasound exam. In those cases requiring the ingestion of water , the GI series should be scheduled for the following day.

Patient Preparation

Pelvic Scans The bladder should be distended to provide an

acoustic window to the pelvic structure in patient undergoing a transabdominal pelvic scan. Outpatients should be instructed to drink enough fluid –at least 16 ounces –to make their bladder slightly uncomfortable at the time of exam.

Since an endovaginal examination is very often used as a follow-up, we now recommended not emptying the bladder 2 hours before an exam rather than drinking water if a transvaginal exam is likely to be performed .

Obstetric Scans For early transabdominal obstetric scans, the

bladder should be distended enough to visualize the lower uterine segments .

After 20 weeks , the bladder should be empty to evaluate properly the cervix and relationship to the placenta

Clinical Applications of Ultrasound

Abdominal ultrasound Gynecology Obstetrics Echocardiography Small parts: thyroid, breast, Scrotum. Vessels Musculoskeletal ultrasound

Clinical Applications of Ultrasound

Abdominal ultrasound Digestive System:

The Liver, Gallbladder, Biliary System, Pancreas, Spleen

Urinary System:

Kidney, Bladder,Prostate

Clinical Applications of Ultrasound

Gynecology Infertility: For Ovulation Induction Intrauterine Conceptive Device Uterine anomalies Ovarian anomalies Rule out Pelvic Mass:

Ovarian masses (cystic , solid, complex)

Uterine Masses

Clinical Applications of Ultrasound

Obstetrics First Trimester Pregnancy Second and Third Semesters Pregnancy Obstetric Measurement and Gestational Age Fetal Growth Assessment Prenatal Diagnosis of Congenital Anomolies Fetal Well-Being and Fetal Death

Clinical Applications of Ultrasound

Vessels Extracranial Cerebrovascular Evaluation Intracranial Cerebrovascular Evaluation Peripheral Arterial Evaluation Peripheral Venous Evaluation

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