How to Read a Petscan

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A PET, which stands for positron-emissions tomography, scan is used to detect cancer in patients. A PET scan can locate cancer, give information on the stage of the cancer and monitor how well treatments are working for current cancer patients. PET scans can even diagnosis benign or cancerous tumors. When a doctor finds a lump in a lung, a PET scan may be able to tell whether surgery and treatment is necessary without having to do a traditional biopsy. PET scans work by using a small amount of a radioactive tracer attached to glucose. The scanner finds areas in the body that are using more glucose and signifies that as a sign of cancer.

Attend a PET/CT Image Interpretation training (see Additional Resources). PET scans should be read by professionals who have been trained (either through regular coursework or through specialized courses) to avoid unclear results or panic in the person who had the PET scan. Doctors should not hand over results without letting the patient know how to read the scan and what it means.

Search the PET scan for hot spots if you are trained in reading PET scans. Hot spots will occur where the body is using more glucose.

Use the Standardized Uptake Values (SUVs) scale to measure the brightness of a hot spot on a PET scan. The scale range is zero to 15. Zero indicates no uptake, and 15 is maximal uptake. Most cancers are above 2 or 3 on this scale.

Decide if the SUVs are in the 2 to 3 SUVs range. If they are, discern whether the patient may have cancer or the hotspots may be a sign of highly metabolic normal tissues. Highly metabolic normal tissues can register in the 2 to 3 SUVs range also, but it would abnormal for this tissue to be closer to 15.

Discuss the patient's options if any cancerous tumors are found in the body during the PET scan. PET scans can show that the tumor is benign or cancerous, and so a biopsy may or may not need to be scheduled for the patient.


If you are not a medical professional trained to read PET scans, then you should consult your doctor. Your physician should not hand over results to you without advice and guidance.