What is a PET / CT scan?

Positron Emission Tomography, also called PET, is a diagnostic tool that produces images that demonstrate organ function. PET images are based on the detection of subatomic particles, specifically positrons.


Positrons are emitted from a radioactive substance administered to the patient and are ultimately detected by special crystals within the PET scanner. This information is then digitized to produce a 3-Dimensional image of the whole body or of a specific organ. With PET/CT, Computerized Tomography images are also obtained, which show detailed views of the structure of the body part being examined. The two types of images are “fused” by a computer into a set of pictures that shows both anatomical detail and function of the area being examined.


PET PET/CT scans are most often used to determine whether a growth is malignant (cancerous) or benign (non-cancerous), to evaluate the progression of disease and to assess the effects of clinical therapies. In addition, PET/CT is used to evaluate patients who have memory disorders such as Alzheimer’s Disease, seizure disorders that are not responsive to medical therapy and for the assessment of cardiovascular disease.


What To Expect

The PET/CT procedure typically lasts 2-3 hours. It begins with an injection of a tiny amount of radioactive glucose (sugar) “tracer” solution that enables evaluation of glucose metabolism (function) in the body. There are no known side effects to this injection. Once injected, you will be asked to rest in quiet room and avoid significant movement or talking, which may alter the localization of the tracer. The resting period lasts approximately 60 min.


As with many diagnostic procedures, there are some risks associated with radiation exposure. Most clinicians believe the beneficial information gained from PET/CT exams outweigh the exposure risks. There are no residual side effects from a PET scan. On rare occasions, CT contrast may cause reaction. You will be able to drive yourself home. Consult your physician before the exam if you may possibly be pregnant or are breast-feeding.


How To Prepare

Instructions for the 12 hours prior to your exam time


Stay on a low carbohydrate diet.

Do NOT engage in any strenuous exercise.

Do NOT chew gum and avoid mints.

Refrain from consuming any caffeine, including any decaf products for 24 hours prior to your exam.


Day of the Exam

Do NOT eat anything six (6) hours prior to your appointment time. Please drink several glasses of water (2-6) and take medications. If you need to eat, please limit yourself to a small protein-only meal. If you are diabetic, please consult your doctor for questions regarding medication.


Wear warm and comfortable clothes. You will receive an injection.

If you're having a CT, you may be asked to drink oral contrast.


You will be asked to sit quietly in the waiting room for 60-90 minutes after the injection.

Wear comfortable, warm clothing. Do not wear jewelry or clothing with metal zippers or buttons. (Sweats are recommended)