707 S. Garfield Ave.
Suite B-001
Alhambra, CA 91801
Tel: 626.227.2727
Fax: 626.227.2799

1661 Hanover Road
Suite 102
City of Industry, CA 91748
Tel: 626.965.8118
Fax: 626.965.8114


PET/CT is the most advanced diagnostic imaging tool for oncology. PET detects changes in cell function within the body while CT provides a detailed picture of the internal anytomy, revealing the location, size, and shape of cellular activity. When the results of PET and CT scans are “fused” together, the combined image provides complete information on cancer location and metabolism.

PET produces molecular images of the body's biological functions and is becoming a very powerful technique in evaluating heart disease and neurological disorders such as Alzheimer's Disease. A PET/CT scan helps your physician diagnose a problem, determine the best approach for treatment and monitor your progress.

The clinical advantages of PET/CT:

  • Detailed diagnostic information not available from other imaging tests.
  • Earlier detection of disease
  • Improved staging of the disease and better monitoring of cancer recurrences
  • Improved targeting of metabolically active cancers for radiation therapy
  • More effective tracking of the results of treatment therap

What is being injected for the scan and why?

For PET scans, a very small amount of a radiopharmaceutical is infused into the bloodstream. The substance contains radioactive molecules that provide imaging information when absorbed, or concentrated in tissue. Areas with rapid cell growth, such as malignant tumors, will show much higher concentrations of the dose than normal healthy tissue. A computer records this information and converts it into pictures for diagnostic purposes.

For a PET/CT scan, you may also receive a contrast agent by mouth or intravenous (IV) injection. The amount of radiation you will receive is about the same as any other radiology procedure. You should not feel any side effects from the material. Most of the radioactivity will be gone by the time you leave the department.

What will I experience during the procedure?

The administration of the radioactive substance will feel like a slight pinprick if given by intravenous injection. You will then be made as comfortable as possible before you are positioned in the PET scanner for the test. You will be asked to remain still for the duration of the examination. Patients who are claustrophobic may feel some anxiety while positioned in the scanner. Also, some patients find it uncomfortable to hold one position for more than a few minutes. You will not feel anything related to the radioactivity of the substance in your body.

Who interprets the results and how do I get them?

Patients undergo PET because their referring physician has recommended it. A radiologist who has specialized training in PET will interpret the images and forward a report to your referring physician. It usually takes one to three days to interpret, report and deliver the results. In order to facilitate interpretation, you may be asked to bring any previous radiologic images with you, such as recent CT (CAT) scans or MRI images.

What are the benefits vs. risks?

  • Because PET allows study of body function, it can help physicians detect alterations in biochemical processes that suggest disease before changes in anatomy are apparent with other imaging tests, such as CT or MRI.
  • Because the radioactivity is very short-lived, your radiation exposure is low. The substance amount is so small that it does not affect the normal processes of the body.
  • The radioactive substance may expose radiation to the fetus in patients who are pregnant or the infants of women who are breast-feeding. The risk to the fetus or infant should be considered in relation to the potential information gain from the result of the PET examination. If you are pregnant, you should inform the PET imaging staff before the examination is performed.

What are the limitations of Positron Emission Tomography?

PET can give false results if a patient's chemical balances are not normal. Specifically, test results of diabetic patients or patients who have eaten within a few hours prior to the examination can be adversely affected because of blood sugar or blood insulin levels.

Also, because the radioactive substance decays quickly and is effective for a short period of time, it must be produced in a laboratory near the PET scanner. It is important to be on time for the appointment and to receive the radioactive substance at the scheduled time. PET must be done by a radiologist who has specialized in nuclear medicine and has substantial experience with PET. Most large medical centers now have PET services available to their patients. Medicare and insurance companies cover many of the applications of PET, and coverage continues to increase.

Finally, the value of a PET scan is enhanced when it is part of a larger diagnostic work-up. This often entails comparison of the PET scan with other imaging studies, such as CT or MRI.