HPET Scan - Frequently Asked Questions (FAQ's)

Q. What does PET stand for?

A. PET is an acronym for Positron Emission Tomography.

Q. What is a PET scan and how does it work?

A. The patient receives an intravenous injection of FDG ( fluorodeoxyglucose) which is a glucose analog labeled with radioactive fluorine (F-18). Following the injection, the patient waits 45 minutes to 1 hour to allow the isotope to be distribute throughout the body. FDG acts like glucose, is taken up by all cells in the body and is then phosphorylated which prevents its exit from the cells.

The more metabolically active cells (cancer) take up a greater percentage of the FDG than normally active cells. F-18 decays by way of positron (positively charged electron) emission. The positron is a short lived subatomic particle that travels a few millimeters. This positively charged particle then combines with the negatively charged electron resulting in the annihilation of both particles.

The result of this interaction is the release of energy in the form of two photons. It is these photons that are detected by the PET scanner. The patient is then taken to the PET scanner for imaging. The scanner creates a 3 dimensional image of the activity throughout the body and areas of increased metabolism (cancers) appear as “hot spots” on the images.

Q. How much of a radiation exposure is there?

A. The total patient dose is less than a CT scan and on the order of two chest x-rays. The radioisotope used (F-18) has a very short half life (about 110 minutes) resulting in a very rapid decay. The majority of the radioactivity is eliminated by 18 hours.

Q. Are there any adverse reactions associated with the exam?

A. There are no adverse reactions resulting from the scan. There are no reported allergies. The exam does not involve the injection of iodinated contrast used with CT scans.

Q. How long does it take for a PET scan?

A. The entire procedure lasts 2 - 4 hours although most are completed in 2 hours.

Q. Should I have a PET scan?

A. Consult your physician.

Q. What should I bring to the PET scan center on the day of my exam?

A. Please bring a copy of your prescription and all pertinent prior diagnostic imaging studies such as CT scans, MRI scans or plain film radiographs.

Wear warm, comfortable clothing.

Q: What patient preparation is there for a PET scan?

A. You should not eat anything after midnight if your exam is scheduled for the morning. Otherwise, a 4 hour fast is required. You should not perform any strenuous exercise the day before the study. Please inform the staff if you are pregnant or breast feeding.

Q. What if I may be pregnant?

A. A PET scan should not be performed. Please consult your physician for certain cases where the benefits outweigh the risks.

Q. What if I am Breast feeding?

A. Breast feeding will not interfere with the scan but breast feeding must be suspended for three days following the scan to allow all the radioisotope to be eliminated from your body.

Q. What if I am a diabetic?

A. Your blood sugar level will need to be stable. Please contact us if your blood sugars are labile.

Q. Do any medications interfere with the PET scan?

A. Some medications may interfere with a PET scan. We will examine the medications you are taking and inform you if a certain medication should not be taken on the day of the exam.

Q. How soon will my doctor receive the results of the scan?

A. Your physician should have the results of your scan within 24-48 hours.

Q. Will insurance cover the cost of a PET scan?

A. Most private medical insurance carriers will pay for the exam. The Centers for Medicare and Medicaid Services (CMS) recently approved Medicare reimbursement for certain disease processes.

Q. What is the difference between a CT scan and a PET scan?

A. A CT scan uses x-rays to define the anatomic structures of the body. The PET scan uses radiolabeled glucose (sugar) that is metabolized by cells of the body and thus displays physiology rather than anatomic structures. For example, a CT scan may detect a small nodule in your lung but often offers no insight into whether the nodule is benign or malignant. The PET scan shows the metabolic activity of the nodule which is typically increased in cases of cancer and decreased or normal in benign etiologies.