The images generated by a positron emission topography (PET) scan essentially provide a visual representation of what is happening in the human body, by revealing metabolic activity differences in organs and tissue. Areas of high activity typically appear brighter than areas with lower levels on PET scans. These bright areas are usually the focus of diagnostic interest. The process of interpreting these scans is complex and involves a number of variables. Radiologists who have received specialized training in nuclear medicine most often perform PET scan image interpretation.
PET scan images are captured by a camera that photographs the path of a radioactive substance as it moves through the body. One of the most common radioactive substances used for PET scans is a simple sugar analog, known as fluorodeoxyglucose (FDG). After receiving this radiopharmaceutical injection, the body metabolizes the sugar and the radioactive positrons carried by the FDG are released. The patient is placed in a PET scanner, which captures the rate of positrons released. This information is then translated into visual images that can be interpreted and used to identify areas of concern.
These images have proven useful in the diagnosis of various cancers, heart diseases, and brain disorders in the human body. The information provided by PET scans usually offers information on a metabolic level, which can be essential in detecting cancer cell activity. To give a more complete picture of what is happening within the body, physicians will sometimes order a combination of a PET scan and a computerized tomography (CT) test. The CT test reveals internal anatomical information that can be used to more accurately pinpoint the location of abnormal growths. Combining these two tests can be especially beneficial for those with cancerous growths.
Interpreting PET scan images is complicated by a number of factors. Visual interpretation alone is insufficient to accurately read a PET scan. Radiologists may use other tools such as the Standardized Uptake Value (SUV) scale to augment interpretation of PET scan images. It is also important to note that PET scans can give false positives. This is especially true where there are abnormal chemical balances in the body, such as when a patient has diabetes or has eaten just before the procedure. If a patient has questions about a PET scan image, scheduling a consultation with a trained radiologist is likely to yield the most satisfactory result.