Nuclear Medicine is a sub-specialty of radiology that uses radioactive compounds, in very small quantities, to study the organs of the body. Nuclear Medicine is especially useful in assessing the functioning of organs, as opposed to only their anatomy. Common Nuclear Medicine procedures include the bone scan, lung scan, hepatobiliary scan, thyroid scan and numerous tests on the heart.
A Nuclear Medicine technologist performs the procedure, which involves injection of a radioactive substance (not an iodine-based "dye"), and usually at least one-half hour of imaging with a Nuclear Medicine gamma camera.
Millions of Nuclear Medicine procedures are performed every year in the U.S. Nuclear Medicine uses radioactive materials, or isotopes, to obtain specific diagnostic information. The isotope is administered by injection, orally or by breathing.
These isotopes transmit a pattern of rays representing the organ size, shape and function. Rays are detected by a special camera that when coupled with a computer, produces an image on a screen.
Side-effects are extremely rare, since the tracer is cleared from the body by natural processes, and the patient's radiation exposure is small, usually comparable to a single chest X-ray. A radiologist interprets the study and informs the physician ordering the test of the results, who then advises the patient.
The individual performing the exam is known as a Nuclear Medicine technologist. The technologist will ask you about your medical history and may ask you for some identification.
If there is any possibility that you may be pregnant, please inform the technologist. After this short interview, the Nuclear Medicine isotope will then be administered appropriately for the type of exam your physician ordered.
When it is time for your scan, the technologist will position you on a scanning table and take the appropriate images for the study. Most of the time you are asked to lie very still on your back and the camera is rotated around you. Each image takes from three minutes to one hour. The length of time for the entire procedure varies significantly. Your doctor's office will discuss with you the amount of time needed for your particular exam or you may call our department.
Many modalities allow visualization of the kidneys, ureters and bladder. To obtain functional data your physician must depend on the Nuclear Medicine department. There are many types of renal scans. Renal studies may take from one to two hours depending on the variety ordered. The patient must lie very still on an imaging table while a small amount of a radioactive drug is administered through an IV.
Hepatobiliary or HIDA scan is primarily a test on the gallbladder, a small organ located beneath the liver that serves as a reservoir for bile. This test can help in diagnosing gallbladder disease. The patient must not eat or drink for at least 8 hours prior to the test, and must avoid any use of opiate medications. In the procedure, the patient lies on his or her back on a Nuclear Medicine imaging table. A gamma camera is positioned above the abdomen, and he/she is injected (in the veins of the arm) with the liquid radioagent. Images are taken for one hour, after which the patient may have a short break. If the gallbladder has become visible by the end of this hour, the second part of the exam is usually performed. During the second procedure, the gallbladder is induced to empty its contents by the injection of an enzyme, CCK, which simulates a fatty meal. This second part of the procedure, which lasts 20 minutes, allows calculation of the Gallbladder Ejection Fraction (GBEF), a measure of the organ's functional capacity.
If your doctor has any concerns about your liver he or she may order a Nuclear liver/spleen scan. This study requires no special preparations and can be completed in as little as 30 minutes. You will be given a small injection of a radioactive material that will be filtered from your blood stream by your liver and spleen. This filtering action will enable the radiologist to differentiate between functioning and non-functioning liver tissue. After the injection you will lay on a Nuclear imaging table while you are being scanned by a gamma camera.
Nuclear Bone Scans
Bone scans use the radiopharmaceutical, 99mTc-MDP, to study the body's skeletal system. The way in which this compound is absorbed by the bones can reveal a range of important pathologies to the radiologist, including bone injury, bone infection (osteomyelitis), and metastatic bone disease (cancer that has spread from a primary organ site to the bones).
In the procedure, the patient is first injected with the liquid radioagent. A waiting period of at least 2 hours follows during which the patient is asked to drink as much liquid as possible, if medically permitted. Outpatients are free to leave the radiology department or hospital during this time.
For scanning, the patient lies on his/her back on a Nuclear Medicine imaging table, and the gamma camera passes slowly from head to foot. This imaging usually lasts about 30 minutes.
Thyroid scans study the size, position and shape of the thyroid gland. The test is usually performed in conjunction with a thyroid uptake procedure, which determines whether the thyroid is functioning too actively (hyperthyroidism), not actively enough (hypothyroidism), or normally. Prior to the test, the patient must avoid all medications and substances containing iodine, including especially thyroid medicines, iodine-containing vitamins, and steroids, and must not have had X-ray procedures using iodinated dyes (please consult your physician for specifics).
The study involves two days, the first for dosing and the second for scanning. On the first day, the patient receives the radiopharmaceutical, usually Iodine-123, in the form of a small capsule to be swallowed. Before administering the capsule, the technologist will take a detailed patient history and answer questions. The capsule has no side effects and involves minimal radiation exposure. This requires less than 30 minutes.
The patient returns the next day for scanning with a gamma camera, thyroid probe and sometimes a physical examination of the thyroid by the radiologist. This requires about an hour.