imaging

G U E L P H N U C L E A R

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A clinician’sguide to

nuclear medicine

Medisys is dedicatedto providing quality

medical imaging services.

TABLE OF CONTENTS

An Introduction to Nuclear Medicine Procedures .............................................................................. 1

Safety Information.................................................................................................................................... 2

Bone and Joint Scan...............................................................................................................................3-4

Brain Scan................................................................................................................................................... 5

Nuclear Cardiology Introduction ........................................................................................................6-7

Perfusion Imaging..................................................................................................................................8-9

Ventricular Function Assessment (MUGA) ....................................................................................... 10

Colloid Liver/Spleen Scan.....................................................................................................................11

RBC Liver Scan ....................................................................................................................................... 12

Hepatobiliary Scan.................................................................................................................................. 13

Lung Ventilation and Perfusion Scan................................................................................................... 14

Thyroid Uptake and Scan ................................................................................................................ 15-16

Renal Scan .......................................................................................................................................... 17-18

Gallium Scan for Infection, Inflammation and Tumor..................................................................... 19

Osteoporosis Detection .........................................................................................................................20

Nuclear Medicine Tomographic (SPECT) Imaging .......................................................................... 21


IMAGINGtnms

A clinician’s guide to nuclear medicine

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AN INTRODUCTION TO NUCLEAR MEDICINE PROCEDURES Why refer patients for nuclear medicine imaging? • Nuclear medicine distinguishes itself from other

diagnostic imaging modalities through its ability to provide a functional image for diagnosis.

• These images demonstrating the function of an organ or lesion (when correlated with the anatomic images of x-ray, ultrasound, CT or MRI), provide the clinician with greater insight into the disease process, or effectively exclude pathology.

How does nuclear medicine work?• Nuclear medicine uses a variety of radioactive-

labelled pharmaceuticals which are designed to localize in specific organs according to physiological interactions. Alterations in the normal distribution of activity, or in the rate of accumulation or clearance, indicate disease states.

• The patient receives this radiopharmaceutical

via intravenous injection, except in the case of radioactive iodine uptake studies, which require the patient to swallow a radioactive 131Iodine capsule and bone mineral estimation using DEXA.

• Images are taken of the patient using a gamma camera which is a detection device only. It maps the distribution of the radiopharmaceutical as it decays. The radiation dose is inherent in the radiopharmaceutical which the patient receives; there is no dose from the equipment. This is important since nuclear medicine procedures require 0.5 to 1.5 hours imaging time.

• A specialized device is used for bone mineral densitometry. An x-ray (DEXA) beam is used to penetrate the bone and allows the calculation of bone mineral content. The radiation exposure received by the patient while undergoing DEXA is approximately equivalent to the background radiation received during flight from Toronto to Vancouver.

The following pages of this guide will provide important safety information about nuclear medicine procedures and summaries of the most common nuclear medicine procedures referred in the course of family practice patient care. If you require information on any other procedure which is not covered in this guide, please call us.

Our goal is to provide the referring physician with the information necessary to ensure that patients arrive at our facilities informed of the procedure they are to undergo. This helps to alleviate any apprehension the patient may be experiencing when a diagnostic procedure is required.

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SAFETY INFORMATIONIs nuclear medicine safe?In the clinical setting, nuclear medicine techniques are entirely safe. However, we try to minimize the dose to the patient, family, community and the environment by:• Having written Protocol Manuals and Policy

and Procedure Manuals to standardize service throughout our facilities and to assist the technologist in every aspect of their profession.

• Following the standards set by: a) The Atomic Energy Control Board b) The Alternative Funding Unit of the Ministry of Health under the Independent Health Facilities Act c) The Bureau of Radiation and Medical Devices of the Health Protection Branch d) The X-Ray Inspection Service of the Ministry of Health

What level of radiation will the patient receive?The most commonly used isotope is 99mTechnetium (99mTc) with a six-hour half-life and 140 keV pure gamma emission. Radiation doses to patients are comparable to those from x-ray procedures. Although exact comparisons are not valid, the whole-body radiation dose is lower than that of whole-body surveys with radiographs, while for specific-site evaluation, the “target organ” for the study may have a somewhat higher dose than with x-rays. Additional images do not add additional radiation dose. All doses are within established guidelines for safety. There are a number of organizations world wide responsible for determining the affects of all levels of radiation on human beings. The long-term effects of the low levels of radiation used in diagnostic imaging are not known,

but no biological complications from diagnostic doses have been reported and the effects are not even measurable for a given patient.

What if patients are sensitive to radio-opaque dyes? Many patients who are referred to us for nuclear medicine studies have previously undergone investigations using radio-opaque dyes. These patients are often apprehensive about having the radioactive injection due to their experience with the adverse reactions associated with radio-opaque dyes. Please assure your patients that there are no documented reactions of this severity for radiopharmaceuticals and no relationship between iodine sensitivity and radiopharmaceuticals has been established.

What about pregnant patients?Pregnancy, or possible pregnancy is a relative contraindication and we try to avoid diagnostic tests under these circumstances unless medically necessary. If the patient is unsure of possible pregnancy and it is not within ten days of the onset of menses, the patient will be asked to rebook the study at the next onset of menses. Patients who insist that the technologist proceed with the procedure will be asked to sign a form documenting their consent. If a patient is lactating, infant nursing should be deferred (pump the breast, and discard the milk) for 36 hours if the radiopharmaceutical used is 99mTechnetium. All other radiopharmaceuticals used in nuclear medicine require a prolonged period of discontinued breast feeding. This information can be obtained by calling any of our nuclear imaging locations. Prolonged contact with infants should be avoided for 24 hours.

Patients who do not speak English MUST be accompanied by someone who can speak English and is willing to explain the procedure to the patient and ensure that all of the patient’s questions have been answered. This is an important safety issue and the study will not be performed if, in the opinion of the attending technologist or physician, the patient cannot provide informed consent.

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BONE AND JOINT SCANIntroductionA mineral change of up to 30-50% is required to be visible on a radiograph. Bone scans demonstrate metabolic changes in bone at the 5-10% level and are thus much more sensitive in the early detection of focal or diffuse skeletal lesions. Abnormal bone scans, in symptomatic patients with normal radiographs, may indicate stress fractures, occult sepsis, arthritis or other lesions in areas difficult to recognize on a radiograph. A positive scan is often non specific, for example, traumatic versus pathologic fracture, and radiographic correlation may be recommended for more specific diagnoses.

The bone scan evaluates the physiological activity of lesions seen radiographically. It can differentiate bone islands from metastases, old fractures from new, active from inactive arthritis and revascularization of avascular necrosis. Most active lesions demonstrate increased uptake of the radiopharmaceutical but avascular bone or highly destructive lesions may demonstrate decreased uptake on the bone scan.

The addition of tomography (SPECT) enhances the sensitivity of diagnosis and, more accurately, localizes lesions particularly in the spine (disc degeneration versus apophyseal arthritis).

In patients with abnormal Alkaline Phosphatase or calcium levels, the bone survey may detect asymptomatic Paget’s disease, metastatic disease, or metabolic bone disease.

Blood flow and blood pool images are useful adjuncts to the bone scan, demonstrating the vascularity of a lesion and any affected soft tissue component. The presence or absence of hyperemia reflects the activity of inflammation, the presence of synovitis in arthritis, the age of a fracture, and the process of repair.

At your request, a Total Body Bone Scan, Joint Survey, or Specific-Site Bone Scan may be performed. Tomographic (SPECT) Imaging may be useful in some situations.

Main Indications• Arthritic survey (blood pool images show synovial

inflammation).• Trauma to detect occult fractures. • Assess healing or complications of fractures.• Postoperative complications (in conjunction with

gallium scans for sepsis).• Bone or joint sepsis (in conjunction with gallium

scan).• Avascular necrosis, acute and revascularization

phase (SPECT may be useful).• Metastatic survey pre- and post-treatment.• Back pain (SPECT very useful).• Undiagnosed causes of bone pain (i.e. osteoid

osteoma, etc.).• Correlate activity of a radiological lesion (bone

island vs. osteoblastic metastasis).• Abnormal alkaline phosphatase (Paget’s disease,

metastases, metabolic bone disease, etc.).

The status of the urinary tract may also be evaluated during a bone scan for renal or pelvic tumors.

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Patient Information• No preparation.• 99mTc labelled methylene diphosphonate, the

radiopharmaceutical required for bone scanning, rarely may cause allergic reactions in highly sensitive individuals.

• The scan is a two-part study performed on one day.

• The patient will be asked to drink at least a litre of any fluid between the initial and second parts and to void as often as possible. This improves the images by decreasing the radiation in the soft tissues and it also decreases the radiation dose to the patient. The patient will be advised to continue to drink and void as often as possible for the remainder of the day.

Part I1. The patient is given an intravenous injection of

the radiopharmaceutical; flow- and blood-pool images are taken demonstrating vascularity and the presence of hyperemia.

2. The patient is free to leave the facility and must drink 4-5 glasses of any fluid and clear the bladder as often as possible. There are no restrictions on eating or any other activity.

3. There is a wait of 2-3 hours before Part II.

Part IIAn additional imaging time of 30-90 minutes is required to acquire images which demonstrate bone metabolism.

Total time required approximately 3 to 4 hours Normal Bone Scan

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BRAIN PERFUSION IMAGING

IntroductionThe distribution of cerebral blood flow may be demonstrated by SPECT imaging, after the injection of a lipophilic radiopharmaceutical which binds to neural cells, relative to blood flow to the area. The distribution of blood may be altered by cerebrovascular disease, migraine headaches, various dementias and head trauma. Correlation with CT and MRI is important in interpreting abnormal brain perfusion images.

Main Indications• Evaluation of dementia (Alzheimers, atrophy etc.)• Headache• Post head trauma

Patient InformationPatients should be instructed to avoid caffeine, alcohol and any other drug known to affect cerebral blood flow.

ProcedureAn I.V. will be set up for the injection. The patient will be injected with the radiopharmaceutical 15 minutes after the I.V. is set up, in a quiet area. The I.V. will be removed 15 minutes after the injection.

Ninety minutes after the injection, the patient will be positioned on a scanning table with his/her head supported by a headrest and strap. The gamma camera will be set up to move in a series of steps around the patient’s head. The scanning time is approximately 30 minutes and it is very important that the patient not move during this time.

Total time required approximately 2.5 to 3.5 hours.

Normal brain perfusion SPECT scan Brain perfusion SPECT scan showing multiple infarcts (arrows)

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NUCLEAR CARDIOLOGY INTRODUCTIONIntroductionMany family practitioners are now taking the initiative in the diagnosis and continuing care of patients with coronary artery disease. If the patient has known CAD, previous myocardial infarction, valvular disease, coronary artery angioplasty or bypass graft, the patient may be referred for a myocardial perfusion scan to detect ischemia or scar due to CAD, or for a MUGA study to assess ventricular function. A medically supervised stress ECG is an important component of the nuclear cardiology study and should be correlated with the imaging results.

Mycardial perfusion tracers such as Myoview, Cardiolite or Thallium distribute in the myocardium proportional to blood flow. A stress perfusion scan is indicated to detect CAD, particularly in patients with non-specific or non-diagnostic ECGs (digitalis effect, previous myocardial infarction, bundle branch block, etc.), or where there is a disparity between the clinical and ECG findings (asymptomatic ST abnormalities, chest pain with normal ECG, etc.), or to evaluate the myocardium at risk following infarction, or coronary artery angioplasty. SPECT (tomography) images improve the sensitivity of detection and improve anatomic localization of the lesion, compared with planar images. A defect seen during stress which is not present at rest is due to ischemia. A fixed defect, that is, one that is demonstrated on both the post-stress and rest images, is likely an infarction. Gated SPECT allows assssement of wall motion and left ventricular ejection fraction at rest.

Computer-assisted exercise multiple gated acquisition ventricular function studies (MUGA) using radiolabelled red blood cells are useful in determining wall-motion abnormalities and ejection-fraction response to exercise. Normally, the ejection fraction will rise during exercise. If there is cardiac

dysfunction due to ischemia, infarction, valve disease or other cardiomyopathy, the ejection fraction will fall and wall-motion abnormalities may occur. Resting wall-motion abnormalities suggest scarring or aneurysm. First-pass cardiac transit times and computer-generated phase analysis of wall motion enhance diagnosis.

Imaging TechniqueImaging protocols for all myocardial perfusion studies include SPECT (tomographic imaging) and gated wall motion studies. SPECT imaging is considered the contemporary gold standard in nuclear cardiology due to enhanced lesion detection. With planar imaging, lesion detection is limited since resolution is decreased by the superimposition of normally perfused myocardium. SPECT imaging allows the myocardium to be reconstructed into thin slices thereby improving image resolution and localization of specific vessel involvement.

StressingStressing of patients undergoing myocardial perfusion imaging may be performed via exercise or pharmacological intervention using Persantine (dipyridamole). All exercise studies are performed using a treadmill unless exercise on a supine bicycle is specifically ordered. Exercise ventricular function studies (MUGA) are performed as supine bicycle exercise studies only.

Persantine stressing is usually indicated when the patient suffers from orthopedic problems which would prevent exercise or when the patient demonstrates left bundle-branch block.

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Contraindications to Persantine Stressing• Allergies to dipyridamole or aminophylline• Asthma• Bronchodilators • COPD• Unstable Angina• Cardiac Failure• Recent Acute MI• Severe debilitation

The following pages provide detailed information regarding each nuclear cardiology study performed at our facility.

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PERFUSION IMAGING

Main Indications • Detection of coronary artery disease. • Typical or atypical angina with normal ECG.• Typical or atypical angina with indeterminate

ECG, i.e. BBB, digitalis effect.• Abnormal ECG in asymptomatic patient.• Non-invasive assessment of pilots, executives, etc.,

with equivocal ECG stress tests.• Follow-up to coronary artery bypass.• Correlation with equivocal coronary angiogram finding. • Questionable myocardial infarction.• Assess myocardium at risk following myocardial

infarction.

The radiopharmaceutical of choice is 99mTc labelled Myoview (tetrofosmin) or Cardiolite (Sestimibi) which provides improved image quality and decreased radiation dose to the patient.

201Thallium may be useful in patients to assess tissue viability post MI.

Patient Information• The patient should be appropriately dressed for a

stress test (running shoes, shorts; women require a short-sleeved, loose-fitting t-shirt).

• Light breakfast, no caffeine.• Preferably off Beta-blockers (on the advice of

the referring physician). Please ask the patient to bring a list of current medications.

• Copy of previous ECG, if available.• Patient will sign a consent form outlining risks

associated with the stress testing.• Stress tests will be supervised by a qualified

physician.• 12-lead ECG tracings recorded before, during and

after exercise.• Allergic reactions are rare.

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Myocardial Ischemia - The defect seen in the stress perfusion images shows significant

improvement on the rest study (arrows)

Normal Myocardial Perfusion scan. Tomographic (“SPECT”) stress and rest images

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Myoview Perfusion Imaging StudyMyoview studies may be performed using one- or two-day protocols. It is preferable to perform the stress and rest images on separate days.

Rest Study1. The patient receives an intravenous injection of

Myoview; one to one and a half hours are required for equilibration and blood-pool clearance. The patient may leave the facility during this interval but must not engage in any strenuous activity during the waiting period or consume any caffeine.

2. The patient then undergoes ECG gated wall-motion and SPECT imaging for approximately 45 minutes.

Total study time of approximately 2 - 2.5 hours.

Stress Study1. The patient will undergo stressing which will

consist of either exercise or persantine infusion. Stressing requires approximately 15 minutes. The patient will not be asked to exercise beyond his or her capabilities.

2. There is a 30 minute to 1.5 hour delay for blood-pool clearance. The patient may leave the facility during the interval.

3. The patient then undergoes SPECT imaging for approximately 40 minutes.

Total study time is 2 - 3 hours.

For those patients who cannot return on a second day, a one-day rest and stress protocol may be scheduled. A one-day protocol requires a larger radiation dose to the patient and a 4.5 - 5 hour total study time. The patient may leave the clinic during waiting periods. Please inform the technologist, at the time of booking, if the test must be completed in one visit.

Thallium Perfusion Imaging StudyThallium myocardial perfusion imaging is performed as a one-day study.

Stress Study1. The patient will undergo stressing which will

consist of exercise or persantine infusion. Stressing requires approximately 15 minutes. The patient will not be asked to exercise beyond his or her capabilities.

2. The patient will undergo ECG gated wall motion study and SPECT imaging immediately post stressing.

Redistribution Study1. The patient has a 3 - 4 hour period of rest

following the exercise, during which time the radiopharmaceutical will redistribute.

2. The patient may leave the facility during this time and will be asked to refrain from strenuous exercise and the intake of caffeine.

3. The patient will then undergo an ECG gated wall-motion study and SPECT imaging.

Total study time is 5 - 6 hours.

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VENTRICULAR FUNCTION ASSESSMENT (MUGA)Main Indications • To assess left ventricular function in patients with

known or suspected myocardial disease or valvular dysfunction.

• To detect regional wall-motion abnormalities (eg. ventricular aneurysm post-myocardial infarction).

• To assess the effect of drug therapy or conditioning in rehabilitation of cardiac patients.

• Non-invasive assessment in patients with equivocal or discordant myocardial perfusion/ECG findings.

*Note: In the presence of significant arrhythmia (ie. atrial fibrillation)the irregular cardiac rhythm will interfere with ECG gating.

Patient Information• The patient should be appropriately dressed for a

stress test (running shoes, shorts, women require a short sleeved loose fitting t-shirt).

• Light breakfast, no caffeine.• Patients will sign a consent form prior to stressing,

outlining risks associated with stress testing.• Stress test will be supervised by a qualified

physician.• Preferably, the patient should be off Beta-blockers

(on advice of referring physician). Please ask the patient to bring a list of his or her current medications.

• Provide a copy of previous ECG, if available.• 12-lead ECG will be recorded before, during and

after exercise.• Allergic reactions are rare.

Procedure1. The patient is given an intravenous injection of a

red blood cell labelling agent which prepares the RBCs for tagging with the radiopharmaceutical.

2. 20 - 30 minutes after the initial injection, the patient is positioned under the gamma camera and injected with the radiopharmaceutical, which will attach to the RBCs and allow blood pool imaging of the heart.

3. A series of ECG gated wall-motion images are acquired at rest, during exercise and post-exercise.

Total study time is approximately 1 hour.

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COLLOID LIVER/SPLEEN SCANIntroductionRoutine liver imaging utilizes a labelled colloidal material which is extracted by the RES (Kupfer cells) surrounding the liver sinusoids. Any lesion replacing or displacing liver parenchyma or lesions altering portal flow will alter the distribution of the tracer. The RES of the spleen, which also concentrates thecolloid, is imaged.

The abdominal flow study may detect vascular abnormalities of the abdomen (ie. aortic aneurysm) and assess the vascularity of mass lesions.

A radionuclide (SPECT) liver spleen scan is more sensitive than ultrasound or CT in detecting diffuse liver disease, and approaches CT in the sensitivity of detection of focal liver lesions such as cyst, metastases, and hemangiomas.

Main Indications • RUQ mass, query Hepatomegaly.• LUQ mass, query Splenomegaly.• Morphological changes in diffuse liver disease, ie.

cirrhosis, hepatitis.• Mass liver lesions (primary, secondary, cysts,

abscess, hemangioma, etc.)• Abdominal trauma, liver or spleen injury.• Metastatic follow-up or preoperative assessment

of tumour.• Hepatoma in cirrhotic liver (in conjunction with

gallium scan).• RUQ pain, hepatitis vs. abscess.• Questionable or equivocal lesion seen on

ultrasound.

Patient Information• No preparation.• 99mTc labelled colloids may cause allergic reactions

in highly sensitive individuals.

Procedure1. The patient receives an injection of the labelled

colloid.2. Approximately 15 minutes post injection, planar

or tomographic (SPECT) images of the liver and spleen are acquired.

Total study time is 1 hour.

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Liver scan for HemangiomaLeft side images: Colloid scan shows parenchymal defect

(arrows)Right side images: Labelled Red Blood Cell scan shows

vascular nature of the lesion

RBC LIVER SCAN

IntroductionA labelled red-blood-cell liver scan, in conjunction with a colloid liver/spleen scan, is useful in the diagnosis of cavernous hemangioma of the liver. The hemangioma is differentiated from other space occupying liver lesions since it will be demonstrated as a “cold” or photopenic area on the liver/spleen scan and a “hot” area (increased activity) on the labelled red-blood-cell scan. The two studies must be performed on separate days, with at least one day between the two. The studies will be acquired as tomographic (SPECT) studies.

Main Indications • R/O cavernous hemangioma.

Patient Information• No preparation. • Allergic reactions are rare.

Procedure1. The patient receives an injection of a non-

radioactive pharmaceutical, which prepares the red blood cells for labelling with the radiopharmaceutical.

2. 20 - 30 minutes after the first injection, the patient is positioned under the camera and receives an injection of the radiopharmaceutical, 99mTc pertechnetate.

3. A series of blood-pool images are acquired.Tomographic imaging is performed 2 hours after the second injection. The patient may leave the facility during the waiting period.

Total study time is 45 minutes immediately post-injection and 30 minutes 2 hours post injection.

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HEPATOBILIARY SCAN

IntroductionRadioactive-labelled drugs which follow pathways of bile are useful in detecting hepatocyte function and excretion, outlining biliary drainage and evaluating gallbladder dynamics. Radionuclide gall-bladder imaging is the most sensitive indicator of acute or chronic cholecystitis and is extremely accurate in diagnosing cystic duct obstruction. The presence or absence of calculi-demonstrated byultrasound is non specific. Abnormalities in biliary dynamics and drainage may be identified in patients with epigastric discomfort, bile reflux gastritis, and post operatively.

Main Indications • Acute cholecystitis (more than 95% accuracy to

exclude or detect). • RUQ discomfort, rule out acute biliary

obstruction.• Diffuse parenchymal liver disease (ie. cirrhosis,

hepatitis).• Postoperative bile excretory pathways.• Liver trauma, bile leak.• Indigestion, bile reflux gastritis.• Severe jaundice (not as useful as ultrasound in

differentiating obstructive from non-obstructive causes).

• Mild jaundice (useful for partial obstruction or intrahepatic segmental obstruction).

• Dilated ducts seen on ultrasound, query obstructed or residual dilatation following previous obstruction.

• Gallstones seen on ultrasound, query significance re: biliary dynamics.

Patient Information• NPO for 4 hours.• Allergic reactions are rare.• Generally one-part study.• If the gall bladder has not demonstrated signs

of contraction at 90 minutes post injection, the patient may be given a fatty meal (if tolerated) to stimulate gallbladder contraction.

Procedure1. The patient is given an intravenous injection of a

radiopharmaceutical, which allows the imaging of the hepatobiliary system.

2. Images are taken sequentially until the full drainage pattern is outlined, usually 60 -120 minutes. Occasionally there may be a need for a second set of images 4 - 6 hours later.

Average study time is 90 minutes, but the study may require several hours (see above). The patient is free to leave the facility during waiting periods if the study has to be extended.

Normal Biliary ScanNote bile ducts, gall bladder and excretion into small bowel

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LUNG VENTILATION AND PERFUSION SCANIntroductionIf you suspect an acute pulmonary embolism, you should refer your patient to the nearest hospital nuclear medicine department. Matched ventilation and perfusion defects or non-segmental perfusion abnormalities have a lower probability for pulmonary embolic disease. Severe ventilatory abnormalities are seen in COPD. Where chronic changes, COPD or pneumoconiosis are present, evaluation of both ventilation and perfusion provides a valuable assessment of lung function.

A recent chest x-ray (within 24 hours of the V/Q scan) is necessary to compare with the scan to evaluate the presence of other parenchymal disease, such as pneumonia which may produce ventilation and or perfusion abnormalities, and will decrease the specificity of the test (ie: matched V/Q and chest x-ray defects will be indeterminate for PE).

Main Indications • Resolution of emboli.• Residual lung function in severe chronic disease.• Pre-operative assessment of lung function.• Pneumoconiosis (in conjunction with gallium

scan).• Mediastinal involvement by neoplasm (in

conjunction with gallium scan).• Perfusion lung scan in conjunction with

radionuclide venogram for phlebitis.

Patient Information• No preparation. • Allergic reactions are rare.

Ventilation Scan1. Ventilation is performed by inhalation of

radioactive aerosols.2. The patient breathes a radioactive aerosol for 5

- 10 minutes after which lung images are acquired for 30 minutes using a gamma camera.

Perfusion Scan1. Perfusion lung scans are performed following an

intravenous injection of 99mTc labelled albumin particles. These particles will not compromise lung perfusion.

2. Immediately after the ventilation images have been completed, the intravenous injection of albumin particles is performed.

3. The distribution of these particles in the lungs is imaged immediately post injection. Imaging requires 30 minutes.

Total study time is 1-2 hours. *Recent chest x-ray (within 24 hours of V/Q scan) or report should be available for comparison.

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THYROID UPTAKE AND SCAN

IntroductionThe measurement of the accumulation of radioiodine (RAIU) in the thyroid gland is an indication of the thyroid trapping at 1 hour and hormone production (organification) at 24 hours. The thyroid scan, using 99mTechnetium-pertechnetate to minimize radiation dose, shows the distribution of thyroid function and helps to determine thyroid morphology (when palpation is equivocal) and to evaluate the activity of a palpable nodule. Hot (functioning) nodules are rarely malignant. Solitary, cold (non-functioning) nodules have an increased risk of malignancy, particularly in young females and male patients, and when they are solid by ultrasound. A history of previous head or neck irradiation is also significant.

Valuable information concerning thyroid morphology and total function is gained when the radioactive iodine uptake (RAIU) and thyroid scan are performed in conjunction with each other. In thyroiditis, which is often painless or silent, the uptake values, clinical symptoms and serum hormone levels may be contradictory. The inflammed gland releases hormone- causing thyrotoxic symptoms, but the uptake values are low due to hypofunction. The scan appearance may range from a gland which demonstrates little or no localization of the radiopharmaceutical, often seen in subacute thyroiditis, to a gland demonstrating a multinodular appearance or diffuse increased uptake, seen in chronic thyroiditis (Hashimoto’s thyroiditis). This is in contrast to Grave’s disease, which demonstrates high uptake values and the typical appearance of a diffusely “hot” gland.Studies performed on patients who are taking thyroid medication reveal the efficacy of thyroid suppression and the presence of autonomous nodules. Normal uptake values: 1 hour less than 4%; and 24 hours 6-24%.

Main Indications • Hyper or hypothyroidism, clinical or biochemical.• Goitre.• Nodule assessment.• Ectopic gland (lingual, thyroglossal duct, or

retrosternal).• Detect primary tumour if secondaries are present

elsewhere.• Occult malignancy: follow-up after neck

irradiation (i.e. acne, ringworm, adenoids).

Patient Information• Two visits, one day apart. Patient is given one

capsule p.o. on day one and one intravenous injection on day two.

• Patients undergoing RAIU must be NPO from midnight on for the first visit only.

• Allergic reactions are rare.• We use a low-dose iodine 131I capsule for uptake

and 99mTc-pertechnetate for scanning to minimize radiation exposure to the patient.

*Note: Recent administration of iodine containing materials such as IVP and gallbladder contrast, exogenous thyroid hormone, propylthiouracil and other drugs, such as iodine containing cough medication, may alter thyroid function. If you wish to refer a patient without discontinuing thyroid medication please advise the technologist.

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Day 11. The patient swallows a capsule

containing 131I. 2. One hour post capsule administration,

a thyroid probe is used to detect the uptake of the 131I in the thyroid gland.

Total Day 1 study time is 1 hour and 15 minutes.

Day 21. At 24 hours the thyroid uptake is again

measured.2. The patient is then positioned under the

gamma camera and given an intravenous injection of a radiopharmaceutical which allows imaging of the thyroid gland.

Total Day 2 study time is 1 hour.

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RENAL SCANIntroductionThe renal scan provides information concerning renal perfusion, function, morphology and drainage with a single intravenous injection of a radiopharmaceutical. Computer quantification of differential renal function is useful in the evaluation of hypertension or other renal parenchymal or obstructive problems. The use of Captopril in conjunction with a renal scan may improve detection of hypertension that is caused by renal artery stenosis.

The renal scan with the administration of Lasix is used in differentiating non-obstructive from obstructive dilatation of the urinary tract. Allergic reactions to nuclear medicine radiopharmaceuticals are rare, and this test may be used safely in patients with sensitivity to x-ray contrast agents.

Radioactive tracers are excreted by filtration by the glomeruli or secretion by the tubules and follow the pathways of urinary drainage. Quantification of differential function is possible by this technique, unlike a radiographic or ultrasound examination. The renal blood flow study and differential renal function are useful in screening patients with hypertension.

Main Indications • Hypertension (asymmetrical flow or function).• Renal failure.• Obstructed kidneys, level of obstruction and

residual function.• Trauma, renal function, urine leaks.• Reflux.• Flank pain, query infarct.

• Renal assessment when iodine sensitivity is present and IVP is contraindicated.

• Vascularity of renal mass lesions (in conjunction with ultrasound).

• Renal excretory pathways, post-operative.• Residual urine volume in bladder.• Lasix stimulation in hydronephrosis (to

differentiate obstructed from non-obstructed dilatation).

Patient Information• Please ask the patient to be well hydrated before

arriving for the study. Patients undergoing a renal scan with Lasix injection or Captopril administration will be asked to drink additional water on arrival.

• Sulphonamide sensitivity contraindicates Lasix administration.

• Allergic reactions to the radiopharmaceutical are rare.

• The renal scan without Lasix or Captopril is a two-part study performed in one day.

Procedure for Renal Scan (without Lasix or Captopril administration)Part I - The patient is given an intravenous injection of the radiopharmaceutical followed by sequential imaging for about 30 minutes.Part II - The patient must return 2 hours post-injection for further imaging (approximately 20 minutes). Total Part I study time 30 - 45 minutes and total Part II study time is 20 - 25 minutes. More>>>

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Procedure for Renal Scan with Lasix Administration1. The patient is given an intravenous injection of

the radiopharmaceutical followed by sequential imaging for about 15 minutes.

2. The patient is asked to void and then a physician administers the Lasix intravenously.

3. Sequential imaging continues for another 30 minutes.

Total study time is 1.5 hours.

Procedure for Renal Scan with Captopril Administration 1. The study begins by measuring the patient’s

resting blood pressure.2. The Captopril is then administered to the patient

per os.3. The patient’s blood pressure is monitored for one

hour.4. The radiopharmaceutical is administered and renal

imaging is performed for 30 minutes.5. Blood pressure monitoring continues to ensure

that the patient’s blood pressure returns to the resting level.

6. If after one hour the blood pressure has not risen to resting level, the referring physician will be contacted for instructions.

Total study time is approximately 2 hours.

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GALLIUM SCAN FOR INFECTION, INFLAMMATION AND TUMOURIntroductionGallium (67Ga) localizes in active inflammatory lesions, as well as in many malignant neoplasms. Gallium scanning is a valuable tool in the bioassay of the activity of septic or aseptic inflammatory lesions, such as sarcoidosis, chronic inflammatory lung disease, complications of prostheses, osteomyelitis, etc.

It is used in the detection and staging of malignancies, such as lymphoma and melanoma, and in differentiating benign from malignant liver masses. If the patient has underlying bone pathology (ie. post-operative or post-infective bone repair), both a bone scan and a gallium scan must be performed to differentiate gallium uptake in infection and bone repair.

Main IndicationsInfection and Inflammation • Bone, acute osteomyelitis vs. chronic sepsis.• Orthopedic prosthesis, sepsis vs. loosening.• Lung infiltrates, sepsis vs. fibrosis (activity of

pneumoconiosis, TB, etc.).• Pyrexia of unknown origin, occult sepsis.• Post-operative complications.• Inflammatory bowel disease.• Urinary tract infections.• Sinusitis.• Sarcoidosis distribution and activity.• Monitor response to therapy of sepsis or

neoplasm.

Tumour• Not for detection of occult neoplasm.• Useful for staging lymphoma, melanoma.• Pre-operative staging of lung carcinoma

(mediastinal spread).• Hepatoma vs. focal fibrosis in liver.

Patient Information• Allergic reactions are rare.• Two-part study, 2 or 3 days apart.

Day 11. The patient is given an intravenous injection

of 67Ga only, unless the gallium scan is to be performed in conjunction with another scan, such as a bone or liver scan.

2. The delay is 48 - 72 hours and the patient may require bowel cleansing if a lesion is suspected in the abdomen. Otherwise normal activity and diet.

Day 2The patient is imaged for 30 - 120 minutes.

**Note: Uptake in a lesion may be suppressed by steroids.

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OSTEOPOROSIS DETECTION

IntroductionWorld-wide experience with bone mineral measurements now indicates that osteoporosis may be accurately detected. There is a definite relationship between bone density and risk of fracture. Osteoporosis is a significant health hazard in post-menopausal women, and in patients with metabolic, renal or GI disorders. Loss of bone mineral increases the risk of fractures of the spine, hip and wrist, resulting in kyphosis, pain or severe disability. Treatment of patients with rapid bone loss, or established osteoporosis may reverse this process and reduce morbidity.

General practitioners are now treating many peri-menopausal female patients with Estrogens, calcium supplements, or other drugs. Early detection and treatment of osteoporosis may prevent the serious complications and deformity associated with recurrent fractures. Bone densitometry measurements can evaluate progression of disease or response to treatment.

Radiographs are insensitive to subtle alterations in mineral content. Bone mineral measurements using the Dual X-Ray Absorptiometry (DEXA) technique is an accurate, sensitive method of detecting osteoporosis. The calcium content of the spine and proximal femur is determined and compared with a reference population, matched for age, race and sex. There is a normal loss of bone mineral after age 40. Patients below the normal range or losing mineral at a faster rate than normal require additional consideration. An estimate of fracture risk, related to the mineral content is included.

Main Indications• Peri-menopausal caucasian or oriental female.• Family history of osteoporosis.• Sedentary lifestyle.• Diet low in calcium.• History of fractures without significant trauma.• Renal or GI disorders.• Steroid medications (ie. arthritis or allergy

therapy).• Follow - up of patients on active therapy for

osteoporosis: repeat at 9-12 months (follow - up of other patients not necessary at less than 18-24 month intervals).

Patient Information• No preparation.• No injections.• The radiation exposure which the patient receives

from DEXA is approximately equivalent to the background radiation received during flight from Toronto to Vancouver.

Procedure1. The patient will be asked to provide a detailed

medical history. 2. The patient lies on a comfortable stretcher while

an x-ray beam passes over the spine and femur.

Total study time is approximately 30 - 45 minutes.

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NUCLEAR MEDICINE TOMOGRAPHIC (SPECT) IMAGINGIntroductionSingle Photon Emission Computed Tomography (SPECT) is a technique which produces cross-sectional scan images. A gamma camera rotates around the patient’s body taking a series of images from numerous angles. A computer reconstructs these multiple views into tomographic slices in transverse, coronal, sagittal and oblique views, similar to CT and Magnetic Resonance Imaging. SPECT images, however map the distribution of function rather than anatomy and are complementary to these other modalities.

Tomography enhances the spatial resolution, permitting more precise localization of a lesion. The elimination of tissue activity above and below the plane in focus results in increased sensitivity of detection and better delineation of the lesion structure.

Tomographic Applications

Bone• Spine for low back pain and post-operative

complications.• Knee for osteochondral fracture, meniscus tears. • Base of skull and temporomandibular joints.• Detection of avascular necrosis of the hips or

knees.

Liver• Improved detection of space occupying lesions.

Brain• Improves detection of lesions.• Separates calvarial and intracranial pathology,

especially post-craniotomy.

Heart• More precise anatomic localization of ischemia or

infarct.

Patient InformationTomographic acquisition does not add additional radiation to the patient (unlike CT).

The SPECT portion of the study takes about 30 - 40 minutes, while the patient lies on a comfortable stretcher.

**Note: Tomographic imaging is not available at all offices. If you require SPECT our technologist will advise.

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