Gamma CT Scan: Purpose, Procedure and Types

An advanced imaging technique in nuclear medicine that combines functional imaging with detailed anatomical imaging is called a Gamma CT scan. It is usually used with SPECT/CT (Single Photon Emission Computed Tomography/CT), which uses a gamma camera to detect the signals of a radiotracer and CT to give detailed images of the body's structures. This combination can be helpful to determine the function of an organ or tissue and its abnormalities. Depending on the clinical need and the type of image requested, Molecular Diagnostics and Therapy involves nuclear medicine imaging in support of the evaluation of various aspects of health.  

What Is a Gamma CT Scan?

A Gamma CT scan combines two imaging techniques. The first is a technique involving the injection of a small dose of radioactive material called a radiotracer, called nuclear medicine imaging. The radiotracer is distributed through the body and becomes concentrated in the organ or tissue of interest. A gamma camera is used to detect the energy radiated by the radiotracer and produce images of the distribution. Then, CT imaging is performed to obtain detailed anatomical information. This combination can give doctors additional information about the structure and function of the area being studied.

What Are the Uses of Gamma CT Scan?

Depending on the condition addressed and the body part being assessed, there are various indications for gamma CT and SPECT/CT. It may be used in:

• Bone imaging: To assess areas of increased bone activity, including certain infections, fractures, arthritis, and suspected bone involvement from disease.
• Heart imaging: To evaluate blood flow to the heart muscle and assess certain heart conditions.
• Brain imaging: To study blood flow and certain neurological conditions, including selected cases involving seizures or memory disorders.
• Kidney and other organ imaging: Certain nuclear medicine studies can assess organ function and blood flow.
• Cancer evaluation: In selected situations, nuclear medicine imaging can help evaluate disease activity or identify areas that require further assessment.

The exact usefulness of the scan depends on the medical condition and radiotracer being used.

Gamma CT Scan Procedure

Before the scan, your health care team will ask questions regarding your symptoms, medical history, medications, allergies, pregnancy status, and any imaging or treatment you've had before. This is dependent on the particular nuclear medicine test. A small dose of a radiotracer is often injected into the body at the time of the procedure. Tracers are sometimes swallowed or inhaled for some nuclear medicine exams. 

When the radiotracer is administered, it must collect and go into the area of interest. The waiting time can be rather long in some studies. You will then be placed on an exam table. While the gamma camera rotates around the body, it detects gamma rays emitted by the radiotracer, which are then used to form an image of the body in SPECT. The CT component of the scan uses X-rays to produce detailed anatomical images, which are acquired alongside the SPECT images. A computer integrates all the information to help create a detailed picture of the area under study. It is likely that you will have to lie still with the images being taken.

Types of Gamma CT or SPECT/CT Scans

There are no specific types of gamma CT scans. These radiotracers are used for various SPECT/CT procedures based upon the radiotracer, organ, disease, and/or organ-specific procedures studied.

Bone SPECT/CT

When physicians require more detailed information about bone activity after the performance of a nuclear medicine bone scan, then a bone  SPECT/CT scan may be performed.

Cardiac SPECT/CT

A cardiac nuclear medicine imaging test can look at the blood flow to the heart muscle. Can be carried out in rest and stress situations, depending upon the clinical question.

Brain SPECT/CT

Selected neurologic evaluations such as epilepsy and some memory-producing conditions may benefit from brain SPECT studies to gather information about cerebral blood flow.

Other SPECT/CT Studies

In a few selected organs and tissues, the use of different radiotracers is possible in SPECT/CT. The correct type is selected depending on the patient's condition and the information that the physician needs.

Gamma CT Scan vs Regular CT Scan

The primary source of information provided by a regular computed tomography (CT) scan is detailed anatomical images formed by an X-ray. A Gamma CT or SPECT/CT provides both anatomical (CT) and nuclear medicine (Gamma) information in one test to assess the distribution of a radiotracer. This concept also makes it possible to obtain information on structure and function; this can be helpful in some clinical questions for which SPECT/CT may be used.

Is Gamma CT Scan Safe?

A tiny amount of radioactive substance is used for nuclear medicine tests. The type of radiotracer chosen varies depending on the exam, and the quantity of radiation used is aimed at acquiring the necessary diagnostic information within the framework of achieving the lowest possible dose that can be achieved without compromising the diagnostic information. The gamma camera does not radiate; it measures radiation from the radiotracer in the body. Patients should also notify the medical staff if they are, or may be, pregnant or breastfeeding, as this information should be taken into account when planning the patient's examination.

Why Is Gamma CT Important?

The biggest advantage of SPECT/CT is that it makes it possible to examine two types of information at the same time. Good information is obtained on the radiotracer and can be correlated with the physiological function demonstrated on CT. This can assist doctors in better understanding some of the abnormalities and whether further tests or follow-up are necessary. But a Gamma CT scan alone cannot rule out all diseases. Results should be interpreted alongside symptoms, medical history, examination findings, and other applicable tests.

Gamma CT Scan at Molecular Diagnostics and Therapy

Molecular Diagnostics and Therapy offers nuclear medicine and other diagnostic imaging services that help diagnose various health conditions. The right scan is chosen based on the patient's clinical needs and the information desired by the treating physician.

Conclusion

In general, Gamma CT scan (also known as SPECT/CT) is a combination of nuclear medicine and CT imaging, which gives information on both the activity and structure of organs and tissues. Some of its uses are in the evaluation of selected bones, the heart, the brain, cancer, and other areas of medicine. As a procedure, it consists of injection of an appropriate radiotracer, and then imaging with a gamma camera and CT scanner. Because some SPECT/CT procedures involve other radiotracers and preparation techniques, it is important for the patient to follow his/her physician's instructions. Molecular Diagnostics and Therapy provides advanced diagnostic and nuclear medicine services to support proper medical evaluation.