PET/CT FAQs

What is PET/CT Scan?

Positron Emission Tomography (PET) is a system that measures the metabolic activity of radioactive glucose, F-18 deoxyglucose (FDG) in tumors. The increased glucose consumption by tumors compared to normal tissue, is translated into increased uptake of FDG on the PET images.

Anatomic localization of the increased uptake of FDG is made possible and accurate by the simultaneous acquisition of the CT scan (PET/CT).

What are the common indications for a PET/CT?

PET/CT is primarily used in oncology for the detection of cancer. It is used to determine whether a lesion is benign or malignant. It is indicated for the assessment of tumor response to therapy. PET/CT is also indicated for the early detection of suspected recurrent tumors and for the diagnosis of metastatic disease.

PET/CT is indicated in a wide variety of cancer including:

  • Lung Cancer
  • Colorectal Cancer
  • Lymphoma
  • Melanoma
  • Ovarian Cancer
  • Breast Cancer
  • Head and Neck Cancers
  • Pancreatic Cancer
  • Brain Tumors

There are neurological applications of PET/CT including the evaluation of patients with memory impairment, Alzheimer's disease, Parkinson's disease, seizure disorders and brain tumors.

There are cardiac applications of PET/CT, such as the assessment of blood flow to the heart muscle and tissue viability from prior heart attacks.

How is the procedure performed?

A technologist will take you to a room where the radioactive substance is administered through a vein in the arm. It will take about 60 minutes for the substance to travel and accumulate in the tissues of the body. During this period, you will be asked to rest quietly and avoid any body movement or talking. After this period of rest, scanning of the whole body will begin and may take about 30 minutes to complete. You will be asked to remain still for the duration of the examination. After the test, you should drink plenty of fluid to flush the substance from your body.

How should I prepare for the procedure?

You should wear comfortable loose-fitting clothes. You should not eat for 5 hours before the test. You will be encouraged to drink water.

If you are diabetic, you should follow specific diet guidelines to control the glucose level during the day of the test.

Because the radioactive substance is very short-lived and decays quickly, it is important to be on time for the appointment and receive the radioactive substance at the scheduled time.

What factors may affect PET/CT results?

Uncontrolled diabetes and elevated blood sugar level can affect the results of the PET/CT.

Patients who have eaten within a few hours prior to the examination may have false PET/CT results.

Because the radioactive substance decays quickly and is only effective for a short period of time, it is important to be on time for the appointment and to receive the radioactive substance at the scheduled time.


When will I know the results?


Once your PET/CT exam is completed, the pictures will be looked at by the radiologist, a specially trained physician who is able to interpret the images for your doctor. The radiologist will send your doctor a written report. You should contact your physician within 2 to 3 days of your exam to make an appointment to go over your results and discuss your next step.


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