A positron emission tomography (PET) scan is a valuable diagnostic imaging tool used to detect many types of abnormalities and cancers in the body, including lymphoma. The scan also helps doctors determine the stage and progression of the cancer beyond the initial tumor, which helps them determine the best course of treatment. A person who is scheduled for a PET scan can expect to spend up to three hours in a hospital or nuclear medicine clinic. He or she will receive a small injection of radioactive material and lie still on a table for about an hour while a machine takes images. The test is painless, and patients are usually allowed to go home immediately afterward if they are in good health.
A doctor usually explains the details of a PET scan for lymphoma before the day of the test. He or she can discuss the actual procedure as well as its risks and benefits. It is important for the patient to provide a thorough medical history, a list of current medications, and allergy information so the doctor can make sure he or she will be a good candidate for the procedure. Dietary and medication restrictions may be put in place for the days or hours leading up to testing to ensure good, accurate results.
When a person arrives at the medical center to receive a PET scan for lymphoma, he or she will typically be asked to fill out insurance forms, liability waivers, and other paperwork. It may take a while to complete the necessary forms, so it is generally a good idea to arrive early. Once the doctor or radiology technician is ready, the patient will be brought to an examination room and asked to change into a hospital gown.
A small amount of radioactive material called fluorodeoxyglucose (FDG) is injected into a vein in the arm about an hour before a PET scan for lymphoma. FDG circulates throughout the blood and lymphatic system. PET scans detect the activity of FDG in the body to create accurate images of tumors and observe how quickly they are growing. The amount and type of radiation received is entirely harmless to humans.
During the PET scan for lymphoma, the patient is asked to lie still on a table that is slid into a large tube, the PET scanning machine. The machine senses radiation waves put off by FDG and creates digital, three-dimensional pictures that can later be interpreted by a radiologist. In most cases, a PET scan for lymphoma takes about one hour. Test results are usually available a few days after the procedure, at which time the patient and doctor can discuss findings and make treatment decisions.