PET (Positron Emission Tomography) differs from other diagnostic imaging technologies, because it measures the biochemical or metabolic activity of cells.  Other technologies, like CT, MRI and X-Ray are looking at specific anatomy of bones, organs or vessels.  PET is measuring whether abnormal cells are metabolizing a tracer agent, called FDG, that has been injected in to the patient’s arm.  Typically a tumor or cancer cell is more likely to metabolize this tracer agent at higher levels than normal cells.   Biochemical or metabolic changes occur in the body before physical changes are seen in other diagnostic imaging.  Thus, PET has emerged as a leading tool in the diagnosis and treatment of cancer.

PET exams are painless, but they do require the patient to receive a sugar-based contrast agent (FDG) that contains safe, short-lived radiopharmaceuticals (also called radioisotopes).  About 1 hour after the contrast agent is injected, the scan can begin.   The scan will produce a detailed 3 dimensional look at the entire body and can reveal any tumor or active cancers that have metabolized the FDG.   

Is Is it uncomfortable? The test itself is completely painless.  You will be asked to lie quietly in the PET scanners “patient couch” during the study.

What can I do to prepare? That day and the Night before Your preparations before the PET exam are very important. Our staff will give you personalized instruction depending upon the nature of your test. In general, the guidelines are as follows: No food or drink after midnight of the day prior to the exam (we want your glucose to be low).  Water, BLACK coffee or tea, and medications are the only exception Patients that are scheduled after 10:30 am may eat a very light breakfast before 7 a.m. If the patient is a diabetic, their blood sugar should be below 150/mg/DL and they should bring their medications with them to our clinic. Wear loose fitting clothing and be prepared to spend 2-3 hours at the clinic.   You may want to bring a sweater or jacket.  The PET scan room will be cold.  At the MRI scan suite Plan to arrive at the CT scan suite at least 1 hour and 15 minutes before your scheduled appointment.  This will allow the necessary time to prepare your paperwork, and have you receive an injection of the the glucose-based contrast agent that is part of the exam.  You will be asked to fill our a brief questionnaire about your medical history, medications, allergies and insurance.

How long does it take? Each examination is tailored to individual requirements, so don’t be alarmed if your exam is different from one that you have had before, or if some additional pictures are taken after the first series is completed.  From start to finish, the scanning usually lasts between 45 and 1 hour.  On occasion, scans can be longer.

What happens after the scan? PET has no side effects or ill effects.  Once the PET staff are sure enough information has been collected, you may leave and go about your normal activities without restriction.   Most of the radioactivity will be gone by the time you leave the department.  However, you should drink as much water as possible for the rest of the day, and empty your bladder often.  This will help remove all remaining radioisotopes from your body within 24 hours.