Positron Emission Tomography

Overview

Mayo Clinic has more than 10 years of experience with Positron emission tomography (PET) scanning and Mayo radiologists have performed scans on more than 8,600 patients. All three Mayo Clinic locations have state-of-the-art PET scanners. The Minnesota and Arizona locations also have a PET machine combined with a CT scanner. Patients and their families receive detailed information and guidance regarding test results. Read more about PET.

Scans showing lung cancer (bright spot in the chest).
At left – CT scan; center – PET scan; right – combined CT-PET scan.

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About PET Scanning

Positron emission tomography is a noninvasive imaging technique that creates three-dimensional images of the heart, brain and other organs of the body. PET scans are mostly used in diagnosing cancer, especially lung cancer, colon and rectal cancer, head and neck cancers and lymphoma. However, they can also be used for heart disease, dementia and seizures.

PET is "metabolic imaging" — it detects changes in cells as they use energy to grow. It identifies rapidly growing cells, such as cancer cells. PET scans can show cancers before anatomical changes are visible and can distinguish scar tissue from active tumors. A small amount of radioactive glucose, called a tracer, is injected into the patient's body. The tracer is absorbed at different rates by different tissue. The camera (positron) detects the radiation coming from the patient's body. A computer constructs a three-dimensional image. Malignancies light up as "hot spots" in the image. A typical scan takes about two hours, including preparation.

As a diagnostic tool, PET can be an alternative to biopsy. Mayo Clinic often combines PET scanning with CT scanning to enhance the accuracy of the diagnosis.

Benefits of PET Scanning

• Very sensitive and specific test; may clarify the results of other tests
• Helps identify cancer that has spread, even if other tests (CT, MRI, ultrasound) cannot find it
• May allow patients to avoid unnecessary biopsies or surgery
• Can lead to more appropriate care and image-guided therapy