Caffeine can interfere with PET scan results

Drinking coffee before having a PET scan may interfere with the results seen, says a study done by Saint Louis University researchers.

Positron emission tomography (PET) or computed tomography (CT) scan is done as a procedure to find out malignant growth or to evaluate the effect of treatment on an already diagnosed malignant growth. In this process a tracer like fluorodeoxyglucose is injected in the body that can be traced with the help of the tomography machine.

Drinking coffee before having a PET scan will interfere with the results as caffeine can affect the myocardial uptake, or the amount of tracer used. With intake of caffeine more fluorodeoxyglucose clusters around the heart, making it difficult to take a look into the lesions of the heart. This effect is same as when the PET scan is taken immediately after the person had done some vigorous physical exercise. Patients who had coffee before the PET scan have a higher myocardial uptake that the patients who did not.

Researchers suggest that patients scheduled for a PET scan should avoid having coffee for sometime before the scan, as even a normal amount of caffeine in the beverage can cause distortions and present a false image.

Reference: Saint Louis University, News release, June 2005