WHAT IS PET?

PET/CT is a dual-purpose imaging device, a combination of PET (positron emission tomography) and CT (computed tomography) imaging techniques within a single piece of equipment. The scans, which are taken at the same time, can be presented separately or as a single, overlapping image. The two techniques offer different types of information about the complex human body. The highly sensitive PET detects the metabolic or physiologic activity within cancer growing cells of the body; CT provides a detailed picture of the body’s anatomy that reveals the location, size, and shape of abnormal cancerous growths. For example, a PET scan can highlight a tumor’s increased glucose consumption, while CT scan reveals the physical location.

A positron camera (tomography) is used to produce cross-sectional tomographic images, which are obtained from positron emitting radioactive tracer substances (radiopharmaceuticals) such as F18 fluorodeoxyglucose (FDG) that is administered intravenously to the patient. The tracer is very safe. Adverse reactions are essentially non-existent.

Alone, each imaging test has particular benefits and limitations, but when the results of PET and CT scans are “fused” together, the combined images provide complete information on cancer location and metabolism. PET/CT also eliminates the common problem of a delay between the two studies, during which time the patient’s condition may change.

In one continuous full-body scan (usually about 20-30 minutes), PET captures images of miniscule changes in the body’s metabolism caused by the growth of abnormal cells, while CT images simultaneously allow physicians to pinpoint the exact location, size, and shape of the diseased tissue or tumor.

Essentially, small lesions or tumors are detected with PET and then precisely located with CT.

There are tremendous benefits of having a combined PET/CT scan:

• Earlier diagnosis
• Accurate staging and localization
• Precise treatment and monitoring

For example:

• Physicians can use PET/CT to differentiate between benign and malignant lesions.
• Surgeons can use PET/CT to determine the optimal location to perform an invasive procedure.
• Radiation Oncologists can use PET/CT to tailor radiation fields reaching all the cancer cells without damaging the surrounding healthy cells.
• Medical Oncologists can use PET/CT to monitor response to treatment.<

WHAT ARE THE BENEFITS OF PET FOR PATIENTS?

• Detailed diagnostic information not available from other tests like CT and MR
• Shorter time for definitive diagnosis
• Enhanced ability to detect disease with fewer invasive diagnostic procedures
• Improved staging of the disease and better monitoring of cancer recurrences
• More effective tracking of the results of treatment therapy
• Less extensive surgeries and avoidance of some surgeries
• Lower overall cost of care

WHY ARE PET AND CT USED TOGETHER?

PET/CT represents the next level of diagnostic imaging power for oncology. PET detects metabolic signals in the body while CT provides a detailed picture of the internal anatomy, revealing the location, size, and shape of cellular activity.

Alone, each imaging test is effective for a wide variety of applications. But when the results of PET and CT scans are "fused" together, the combined image provides complete information on cancer location and metabolism.

For more specific information about PET/CT and what to expect if you are scheduled for an exam, please download the following brochures: PET/CT PATIENT INFORMATION GUIDE

LINKS

National Oncology PET Registry
San Diego County Cancer Navigator
Susan G. Komen for the Cure
CyberKnife of Southern California at Vista
American Medical Association
American Society of Nuclear Cardiology
Society of Nuclear Medicine
North County Radiology Group