The procedures that produce PET/CT, PET/MRI, and PET scan images allow physicians to evaluate the metabolic physiology (functional behavior) of the tissues in the body. Areas affected by most types of disease will appear much brighter on the images than healthy tissue.
Below is a list of the various types of PET studies that referring providers may request and some representative images:
PET demonstrates patterns of cellular activity throughout the body, especially those organs that use glucose as their primary energy source. This normal PET scan shows Fluorine-18 (radiotracer) labeled glucose, known as FDG, as it is distributed through the body. The brain, thyroid, heart, kidneys, bowel, and bladder are all shown demonstrating normal FDG uptake, while inflammation or cancer would typically show a more intense and different pattern of uptake.
Normal whole body PET scan. PET shows the organs that normal demonstrate FDG uptake, which are the organs that derive a high percentage of their energy from glucose (FDG radiotracer is a glucose analogue)
While the modality can be used to evaluate many diseases, the most common clinical role for PET is for cancer detection or follow-up. Once the radiotracers have been injected and have distributed throughout the body, a PET scan for cancer will demonstrate very bright spots on the study in regions of hypermetabolic tumors, which is the most common type of cancer variant.
Whole body PET/CT scan demonstrating colon cancer, seen as an area of hypermetabolic uptake (orange color) within the ascending colon on the body's right side
The brain PET scan is an effective tool for assessing a wide range of neurological disorders, including Alzheimer’s disease, schizophrenia, epilepsy, and dementia. Because brain metabolism of glucose and oxygen correlates with brain activity, these images can help radiologists diagnose neurological disorders at very early stages.
PET/MRI of the brain showing postoperative changes in the posterior left cerebrum (parietal lobe), demonstrating no uptake (no orange color), with otherwise normal gray matter activity (orange and red color)
The PET scan lung procedure is used for assessing the presence of lung cancer, determining the stage of the disease, and monitoring its progress after treatment has begun. If on the PET scan lung cancer should appear, the computer illustrates highly detailed images of the malignant growth and its activity within the lung(s).
PET/CT scan through the chest demonstrating locally aggressive lung cancer represented by orange-color hypermetabolic uptake posterior to the heart
The PET Scan metastatic cancer provides a sharp and detailed image of the spread of cancer cells throughout the body, often well before other imaging modalities can demonstrate abnormalities. If on the PET scan metastatic cancer appears, there will usually be several bright spots that indicate which organs have been affected by the disease.
Whole body PET/CT scan demonstrating renal cell carcinoma metastatic to the paraaortic lymph nodes (series of 5 bright yellow ovals in the middle of the abdomen)
The lymphoma PET scan is used at all stages of the disease. The lymphoma PET scan can assess whether lymphoma is present, can define the disease’s stage, and can guide and assess responses to treatment. Both Hodgkin's and non-Hodgkin's lymphoma can be visualized on PET scan images.
Whole body PET/CT scan of extensive lymphoma, with multiple malignant nodes within the bilateral axillae (armpits) and immediately inferior to the liver (large masses of irregular orange color in both areas)