Nuclear Medicine
 What
Is Nuclear Medicine?
How Does Nuclear
Medicine Work?
3-Phase Bone Scan
Biliary Scan / Gallbladder
Ejection Fraction
Captopril Scan
Gastric Emptying Scan
/ Reflux Scan
Gated Cardiac Scan
GI Bleed Scan
Liver / Spleen Sulfur
Colloid Scan
Myocardial Perfusion
Scan
Parathyroid Scan
Renal Nuclear Scan
Spect Imaging
Thyroid Uptake and
Scan
Ventilation and Perfusion
Lung Scan
Whole Body Bone Scan
What Is Nuclear Medicine?
Nuclear medicine is a safe and painless imaging technology, which
uses very small amounts of specially formulated radioactive materials
(or tracers) to help diagnose and treat a variety of diseases. Nuclear
medicine provides physicians information about medical problems
based on how parts of the body function as differing from x-ray,
which demonstrates a body's appearance (or structure).
All nuclear medicine exams involve IV injection, inhalation and/or
swallowing of specially formulated compounds (tracers) with imaging
at timed intervals. Tracers are attracted to specific organs, bones
or tissues in the body, which then are detectable by special types
of cameras. Reactions to these tracers are rare. The total amount
of radiation a patient receives from a nuclear medicine examination
is comparable to that received during a diagnostic x-ray.
Some examinations require special positioning, and most exams take
one to two hours to complete though some will take longer.
Nuclear medicine testing is commonly used in children to evaluate
bone pain, injuries, infection or kidney and bladder function. Common
nuclear medicine applications include:
- Diagnosis and treatment of thyroid conditions
- Cardiac stress tests to analyze blood flow to the heart muscle
- Bone scans for detection of cancer, infection or subtle bone
injuries
- Lung scans for blood flow to the lungs and air exchange
- Liver and gall bladder scans
How Does Nuclear Medicine Work?
Radioactive atoms are attached to a carrier material, which travel
to a receptive organ or tissue. A special camera (gamma camera)
is then used to take a picture of the radioactive material in the
organ to be studied.
Common radioactive atoms include technecium 99m and iodine 131.
Common organs studied include bone, lungs, kidneys, stomach or thyroid
glands.
3-Phase Bone Scan
3-phase bone scan is primarily used to evaluate patients with suspected
bone infections (osteomyelitis).
Stage 1 of a 3-phase bone scan involves IV injection of a radioactive
tracer and short sequenced imaging of the blood flow that is occurring
in the area of concern, frequently a hand or foot. In the second
phase of the exam, an image of the soft tissue is obtained followed
by the 3rd phase, which includes delayed images 3 or 4 hours later
of the specific area. Third-phase images enable imaging of the bone's
functional uptake of the tracer. Images obtained in phases 1 and
2 enable evaluation of blood flow to the area of concern.
Biliary Scan / Gallbladder Ejection Fraction
Also called: HIDA scan
The biliary scan with gallbladder ejection fraction is the most
commonly performed liver nuclear medicine examination. Today, the
biliary scan is used to evaluate the function of the liver, biliary
tree, gallbladder and bile ducts for possible obstruction. The biliary
scan may also be used to evaluate suspected abnormal contraction
of the gallbladder, which may justify the need for its surgical
removal.
Biliary scan involves IV injection of a radioactive tracer, which
reaches the liver and enables imaging of the functional excretion
of bile from the liver and the biliary tree. The gallbladder, which
acts as a reservoir and the common bile duct is also imaged.
If poor contraction of the gallbladder is suspected, a medication,
CCK, can be injected, to stimulate gallbladder contraction. The
amount of activity, which is excreted by the gallbladder is measured
and the "ejection fraction" is calculated. Patients with
low ejection fractions usually have poorly functioning gallbladders.
Plan for an additional 1 to 2 hours to complete your exam.
Captopril Scan
Captopril scan is variation of renal nuclear scanning, which allows
for enhanced imaging of impaired blood supply to the kidney. Captopril
scan requires that a renal nuclear scan is performed first followed
by patient ingestion of captopril, a medicine (in capsule form)
which dilates small vessels of the kidney.
A repeat renal scan is performed 30 minutes later. Abnormal renal
function caused by decreased blood flow to the kidney will be exaggerated
for a short period after captopril. By comparing the before and
after scan the blood flow decrease can be evaluated.
The patient should plan for 1 to 2 hours to complete this exam.
Gastric Emptying Scan / Reflux Scan
Gastric emptying scan / reflux scans are performed on children
and adults, who experience difficulty passing food or liquids from
the stomach.
These scans require a patient to eat / drink a soft food such as
oatmeal or a liquid mixed with trace amounts of a radioactive compound
followed by imaging and measurement of gastric emptying over a period
of about 1 hour. The examination will demonstrate if emptying is
too rapid or more importantly, delayed or too slow. The patient,
monitored throughout the exam, is also evaluated for reflux (return
of food or liquid up the esophagus).
The patient should plan for 1 to 2 hours to complete these exams.
Gated Cardiac Scan
Also called: Ejection fraction study
A gated cardiac scan is performed to evaluate the ability of the
heart to pump blood. The examination can determine how effectively
the muscle of left ventricle of the heart is pumping (contracting)
by measuring the amount / percent of blood in the heart that is
ejected when it beats (ejection fraction).
Gated cardiac scans require the administration of a radioactive
tracer into the bloodstream, to allow visualization of the beating
heart on images. During this exam, EKG (electrocardiogram) leads
are attached for purposes of electronically timing ("gating")
the intervals of contraction.
GI Bleed Scan
The GI (gastrointestinal) bleed scan is typically performed to
determine the source of GI bleeding when endoscopy or colonoscopy
fails to identify the source.
GI bleed scanning involves IV injection of a radioactive tracer,
which tags to the red blood cells and travels through the blood
system over a period of hours (up to 24). Blood, which leaks into
the intestine may be detected by images of the tracer, which appear
in the colon or small bowel.
Patients should plan for an additional 2 hours to complete this
exam.
Liver / Spleen Sulfur Colloid Scan
Liver / spleen scan, common in the past, may still be used in rare
circumstances to evaluate defects of the liver or spleen or to evaluate
disorders of the liver such as cirrhosis. Liver / spleen scanning
has been largely replaced by more sensitive CT.
Nuclear medicine liver / spleen scanning involves IV injection
of a radioactive tracer, sulphur colloid. The patient is positioned
to lie on his / her back for imaging of the abdominal area from
several positions.
Myocardial Perfusion Scan
Myocardial perfusion scan is performed to evaluate the patient
for narrowing (atherosclerosis), of the coronary arteries, which
supply blood to the heart muscle.
The examination involves injection of a radioactive tracer into
the arm followed by imaging of the heart while the patient is at
rest. EKG (electrocardiogram) leads are attached to the patient
and a treadmill test is performed. The patient is exercised to the
maximum level he / she can tolerate at which time a second radioactive
tracer is injected intravenously. The tracer enables imaging and
analysis of blood flow to the heart muscle.
The rest and exercise scans are compared to determine if sufficient
blood is delivered to the heart during exercise. Decreased delivery
of tracer during exercise is often the source of chest pain and
may indicate a narrowing of the coronary artery, which could lead
to a future heart attack.
Parathyroid Scan
Parathyroid scan is performed to evaluate suspected overactive
functioning or tumor (adenoma) of the parathyroid.
Parathyroid scan involves IV injection of the radioactive tracer,
technetium, nuclear medicine imaging and SPECT imaging of the neck
and the upper chest. Some parathyroid glands are found in an abnormal
position in the upper chest. SPECT images allow for more clarity,
as detection of parathyroid adenomas can be very subtle.
Renal Nuclear Scan
Also called: Renal scan
Renal nuclear scan is generally performed to determine if kidney
function is impaired. The scan is also used to evaluate possible
obstruction. In addition, renal scans can assess the normal function
of a kidney and calculate the glomerular filtration rate (a measure
of renal function).
Renal nuclear scan is commonly used to determine if there is adequate
blood supply to the kidney. In addition, renal scans can assess
the normal function of a kidney and the relative function of both
kidney to renal function, calculate the glomerular filtration rate
and determine if obstruction is present.
Renal scan involves IV injection of a radioactive tracer, which
concentrates in the kidney and is excreted by the kidney. Images
are obtained of the tracer transiting the kidney. If an artery supplying
blood to the kidney is narrowed, delayed blood flow may be evident.
The patient should plan for an additional 1 to 2 hours to complete
this exam.
SPECT Imaging
SPECT imaging is an imaging method, which allows for enhanced image
clarity of a specific area of concern. SPECT imaging (single photon
emission computed tomography) produces images in sliced sections
like CT. SPECT imaging may
used to evaluate back pain in the young patient or to evaluate a
concern, which may have a subtle presentation, such as parathyroid
tumor.
SPECT imaging generally involves IV injection of radioactive tracer
and imaging of an area of concern at timed intervals over a period
of several hours.
Thyroid Uptake and Scan
Thyroid uptake and scan is performed to evaluate the appearance
of the thyroid gland. The scan also will reveal if the thyroid is
homogeneous or if it has nodules within the gland.
Thyroid uptake and scan involves swallowing a radioactive iodine
compound in the form of a capsule and imaging of the neck 4 hours
and 24 hours later to demonstrate the "uptake" of tracer
by the thyroid and evaluate the metabolic function of the gland.
The amount of "uptake" in an overactive gland is high.
Ventilation and Perfusion Lung Scan
Also called: VQ scan or lung scan
Ventilation and perfusion lung scan has played a critical role
in the detection of potentially life threatening pulmonary emboli
(a blood clot which travels to the lung), however, CT
pulmonary angiogram has evolved as the more sensitive test for
this purpose.
The lung scan includes two scanning components, perfusion and ventilation.
The perfusion scan involves IV injection of a radioactive tracer,
which flows to the small vessels of the lungs and enables imaging
of the distribution of blood supply to the lungs. The ventilation
scan involves inhalation of a radioactive aerosol compound, which
enables measurement and imaging of the exchange of air within the
bronchi and the trachea. The results of the two scanning components
are then compared.
Patients with pulmonary embolism, as a result of a blocked artery
and no other underlying disease, will demonstrate decreased (defective)
blood flow (perfusion) to an area, however ventilation (air exchange
to the lungs) will be normal. Persons with other lung disease, such
as emphysema, will demonstrate matched abnormalities in both perfusion
and ventilation. The key to diagnosis of pulmonary embolism is unmatched
results between perfusion and ventilation.
Ventilation and perfusion lung scan takes 1 to 2 hours to complete.
Whole Body Bone Scan
Whole body bone scan is generally performed to evaluate skeletal
pain or possible tumor spread to the bones (metastasis). MRI is also used as an examination for evaluation of bone marrow.
Whole body bone scan involves IV injection of a radioactive tracer
and imaging of the whole body 3 to 4 hours later. The tracer, which
is made in part from chemicals that are similar to those in bone,
included within the bone and allows for visualization of the bone
where bone metabolism is abnormal. The uptake of tracer is non-specific.
The uptake may be the result of an old or new injury (fracture)
or infection. X-rays of an area may be necessary to further evaluate
the cause of an abnormal scan.
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