Nuclear Gamma Scan: Purpose, Procedure and Types

A gamma scan is an imaging technique using nuclear medicine to assess the functioning of certain organs and tissues. This process uses a minimal amount of radioisotopes or radiotracers in conjunction with the camera to visualize body activities. While there are some imaging techniques that mainly focus on showing the anatomical structures of the body, a gamma scan can also offer indications of the functions of the organs involved or the movement of the radiotracers through the body.

Nuclear medicine imaging is used to help evaluate various medical conditions in Molecular Diagnostics and Therapy. The type of scan proposed depends on the symptoms, medical history, and the clinical question.

What Is a Nuclear Gamma Scan?

A nuclear gamma scan, or gamma camera scan, is a diagnostic test that identifies gamma rays that are emitted from a radioactive substance within the body. Typically, the radiotracer is administered via injection, although the capsule or liquid form is sometimes used. The tracer is targeted to specific organs or tissues. Once the signal is captured by the gamma camera, it's processed by the computer to generate images. These images can be used to determine the functions of different organs and detect regions of the body that require additional investigation. Interpretation of results is considered with symptoms, examination, and other tests. 

What Are the Uses of a Gamma Scan?

Gamma scans are used to investigate different health conditions depending on the organ being examined. Common applications include:

• Bone evaluation: Helps assess certain bone abnormalities, infections, injuries, and possible spread of cancer to bones.
• Heart assessment: Some nuclear medicine scans evaluate blood flow to the heart muscle.
• Kidney function: Renal scans can assess kidney function, drainage, and certain blockages.
• Thyroid evaluation: Thyroid scans help examine the gland's structure and activity.
• Liver and gallbladder assessment: Selected scans evaluate bile flow and gallbladder function.
• Cancer evaluation: Certain nuclear medicine studies help assess disease activity and monitor treatment response.

The specific test is selected according to the condition being investigated. A gamma scan does not diagnose every disease on its own. 

Types of Nuclear Gamma Scans

The term gamma scan covers several examinations. The main types include:

1. Planar Gamma Scan

This type of scan produces a two-dimensional picture of the organ or region of interest being looked at. Images are usually taken from fixed positions, such as front and back views.

2. SPECT Scan

Single photon emission computed tomography (SPECT): a gamma camera is able to rotate around the patient and produce 3D images. It can give information on where the tracer is distributed in an organ and its distribution state at a more detailed level.

3. SPECT/CT Scan

SPECT/CT is a nuclear medicine scan performed in conjunction with computed tomography (CT). On a SPECT scan, the information is about the activity of the tracer, and on a CT scan, it is about the structure. The fusion of pictures can assist doctors in pinpointing the exact location of an irregularity more clearly. 

How Is a Gamma Scan Performed?

The procedure is different depending on the type of scan and the organ being scanned. The general steps are as follows. First, the healthcare team inspects the patient's medication, preparation, and medical history. A small amount of the radiotracer is typically injected into a vein. Some scans require the tracer to be swallowed.

Depending on the area being examined, the patient may have to wait until the tracer reaches the area. Waiting times vary with the type of test and can range from relatively short to hours. The gamma camera detects the gamma rays emitted by the tracer while the patient lies on the imaging table. Appropriate images are required, and the patient may be asked to move or turn to get the best views. An expert then looks at the pictures and writes a report for the referring doctor.

How Should You Prepare for a Gamma Scan?

Prep varies with the scan obtained. Many scans need no fasting, but some, such as hepatobiliary or cardiac stress studies, do. Follow the instructions for your specific scan. Before the test, tell the doctor or technologist what medications and dietary supplements you are taking, if you have had any medical tests or surgery recently, and any medical conditions or allergies that might affect the test. 

It is important to inform the team if you are pregnant, or may be pregnant, or are breastfeeding, as this may impact on which and when the examination is performed. Never stop or change any medication without your healthcare professional’s direction.

Is a Gamma Scan Safe?

The amount of radioactive substance used in a nuclear medicine scan is carefully checked. Most diagnostic gamma scans are non-invasive, with few side effects, and are generally well tolerated. The amount of radiation the patient receives from the tracer is considered when deciding whether the test is appropriate. 

The benefits and risks are dependent on the exam and/or patient situation. Any special precautions will be explained by the healthcare staff, including those pertaining to pregnancy or breastfeeding. Most patients can resume normal activities after the scan unless told otherwise.

What Is the Difference Between a Gamma Scan and a CT Scan?

A gamma scan detects signals from the radiotracer inside the body and may be used to give information about organ function. CT scans are imaging tests that involve using X-rays to create detailed images of the structure of that part of the body. Some exams involve the use of both techniques (SPECT/CT), which enables physicians to compare information related to function with that related to anatomy. The choice will vary depending on the medical question being studied.

Conclusion

The nuclear gamma scan can be used as an effective diagnostic test to assess the function of certain organs and tissues. There are different types, all offering a different amount of detail for specific clinical needs: planar imaging, SPECT, and SPECT/CT. The preparation time, time for the scan, and safety protocols depend upon the examination, and so patients should follow the instructions of their healthcare team.

Molecular Diagnostics and Therapy offers diagnostic services to support the evaluation and monitoring of health conditions. Choosing the correct test always depends on the patient's requirements and the guidance of the prescribing doctor.