Objective To describe the pitfalls in positron emission tomography/computed tomography （PET/CT） imaging and classify them according to the principles of their generation. Methods We summarized retrospectively the 18F-fluorodeoxyglucose （FDP） PET/CT imaging pit-falls through reviewing the PET/CT images of 872 patients. The pitfalls were divided into artifacts and infrequent physiological uptake

and the artifacts were further classified according to their causes. Meanwhile

we calculated the incidences of various pitfalls. Whether the PET/CT pitfalls influenced the diagnostic decision was analyzed. The appearances of pitfalls in PET were also described. Results Pitfalls could be found in PET/CT images of 684 （78.4%） patients. Artifacts were found in 664 （76.15%） patients

and could be classified into self-factor artifacts and equipment-or technology-related artifacts. Among self-factor artifacts

respiratory motion （57.5%）

postprandial or hyperglycemia artifacts （2.41%）

and metal or high density matter artifacts （1.38%） were frequent. As for equipment- or technology-related factors

injection point outleakage or radiotracer contamination （13.88%） and truncation artifacts （1.83%） were most common ones. Infrequent physiological FDG uptakes

including fatty uptake

endometrial uptake

and bilateral breast feeding period uptake

were found in 20 （2.29%） patients. Among all pitfalls

the artifacts in 92 （13.4%） patients and infrequent physiological uptakes in 6 （0.88%） patients affected the diagnostic results. Artifact images in PET could be described as hot or cold area and the images of infrequent physiological uptake were always shown as hot area. Conclusions The incidence of pitfall in PET/CT imaging was high and the causes of pitfalls are various. Among all causes that artifacts generated

respiratory motion is the most common. Some pitfalls may disturb clinical physicians’ decision

so it is important to recognize artifacts and physiological uptake

and distinguish them from pathological uptakes.