What is molecular imaging/nuclear medicine?
Nuclear medicine is a specialized area of radiology that uses very small amounts of radioactive materials, or radiotracers, to examine organ function and structure. This branch of radiology is often used to help diagnose and treat abnormalities very early in the progression of a disease, such as cancer.
Nuclear imaging enables visualization of organ and tissue structure as well as function. The extent to which a radiopharmaceutical is absorbed by a particular organ or tissue may indicate the level of function of the organ or tissue being studied.
A tiny amount of a radiotracer is used during the procedure to assist in the examination. Several different types of radiotracers are available, including forms of the elements technetium, thallium, gallium, iodine, and xenon. The type of radionuclide used will depend on the type of study and the body part being studied.
After the radionuclide has been administered and has collected in the body tissue under study, small amounts of radiation will be emitted and detected. The most common type of detector is the gamma camera. By measuring the behavior of the radionuclide in the body during a scan, the radiolgist can assess and diagnose various conditions.
In planar imaging, the gamma camera results in two-dimensional (2D) imaging. Single photon emission computed tomography (SPECT) produces images of the organ similar to a CT scan. In certain instances, such as PET scans, three-dimensional (3D) images are produced.
How are nuclear medicine scans done?
As stated above, nuclear medicine scans may be performed on many organs and tissues of the body. Each type of scan employs certain technology, radionuclides, and procedures.
A nuclear medicine scan consists of injection of the radiotracer and subsequent imaging. The amount of time between administration of the tracer and imaging may range from a few moments to a few days, depending on the body tissue being examined and the tracer being used. Some scans are completed in minutes, while others may require the patient to return a few times over the course of several days.
Although each facility may have specific protocols in place, generally, nuclear imaging studies follow this process:
- The patient will be asked to remove any jewelry or other objects that may interfere with the procedure.
- An intravenous (IV) line will be started in the hand or arm.
- The patient will lie flat on a table in the procedure room.
- The radionuclide will be injected.
- The gamma camera will be positioned over the patient and will obtain images through the body.
- The patient may be asked to change positions during the test.