Both positron emission tomography (PET) and gallium scans are nuclear imaging tests used for the diagnosis of disease, treatment staging and assessment, and monitoring for signs of relapse. Both are used to safely identify tumors, infection or inflammation inside the body, but there are differences. Let’s look at both scans.
What is a Gallium Scan?
A nuclear medicine gallium scan involves a radioactive material called gallium-67, which is injected into a vein. It attaches itself to proteins in the blood and spreads throughout the body. Inflamed, infected or malignant cells in the bones and some organs soak up gallium so they can be imaged by a special gamma camera. These pictures are sent to a computer for analysis.
It can take the area being studied anywhere from 6-48 hours to absorb the gallium, depending on what organ and/or disorder is being investigated, so this procedure is usually split into more than one appointment. The scan itself is simple. You lie back on a special table while the scanner isolates what organs or tissues have collected the gallium. Most gallium scans take about 30-60 minutes.
While gallium is a radioactive material, it produces about the same radiation exposure as a standard x-ray, so it is considered quite safe. However, it is not advised for women who are pregnant or breastfeeding.
What Can a Gallium Scan Find?
Gallium scans are used by radiologists to help diagnose:
Certain cancers, such as lung tumors and Hodgkin lymphoma (HL)
Unexplained fever
Infection of the bone (osteomyelitis) or tissue (cellulitis)
Respiratory infection
Inflammation/scarring of the lung (sarcoidosis/pulmonary fibrosis)
It is also used after cancer treatment to help assess the effectiveness of treatment.
What is a PET Scan?
Positron emission tomography, or PET, is a nuclear medicine imaging scan that, like a gallium scan, uses a small amount of a radiopharmaceutical, often F-18 fluorodeoxyglucose, which is a molecule similar to glucose. It absorbs quickly, usually within 30-60 minutes. The radioactive material is injected into a vein, where it spreads to and collects in organs and tissues with abnormally high metabolic or biochemical activity, particularly those related to cancer cells, certain brain disorders, and coronary artery and heart disease. It also uses images captured by a gamma camera that are sent to a computer for analysis. The scan itself usually takes about 30 minutes to complete.
What Can a PET Scan Find?
PET enables examination of organs and systems as they’re functioning, revealing blood flow, glucose metabolism, oxygen use and other processes on a cellular level. PET is used to diagnose:
Tumors of the brain, breast, thyroid, lung, colon and other organs
Lymphoma
Heart disease
Brain disorders like seizures, epilepsy, dementia and Alzheimer’s disease
As with a gallium scan, PET is often used to monitor the effectiveness of treatment and signs of cancer recurrence.
The Basic Differences Between the Two Tests
As you can see, both scans share a lot of commonalities. So, what are the differences?
A PET scan is used to evaluate the metabolism and function of bodily tissues to identify and assess disease.
A gallium scan is used to evaluate the amount of radiotracer absorbed by bodily tissues to identify and assess disease.
A PET scan can be used to diagnose and monitor not only cancer, but also certain heart and brain diseases and disorders.
A gallium scan may be more useful than PET for discovering infection and inflammation.
A PET scan can be completed in a single visit.
A gallium scan usually requires two to three visits to complete.
RAO for Nuclear Medicine Imaging
Since 1973, RAO has been a trusted provider of medical imaging and therapeutic interventional services. RAO is accredited by the American College of Radiology in nuclear medicine and a range of other leading-edge services for accuracy, safety and best practice standards. Our team of Board-certified radiologists includes doctors who are fellowship-trained in nuclear medicine, diagnostic imaging, and other areas of specialization. RAO is dedicated to the highest level of accuracy, efficiency, and safe, minimally-invasive interventional treatments for a variety of diseases and disorders.
