Detection of clinically unexpected malignant and premalignant tumors with whole-body FDG PET: histopathologic comparison.

Purpose: To determine the clinical importance and malignant potential of unexpected abnormal foci of hypermetabolism at fluorodeoxyglucose (FDG) positron emission tomography (PET) performed for evaluation of malignancy.

Materials And Methods: A total of 1,750 FDG PET scans were obtained to evaluate a variety of known or suspected malignancies. Each scan was evaluated for abnormal unexpected hypermetabolism based on unusual location (ie, foci that did not conform to the usual distribution of metastases given the primary tumor for which the PET scan was requested) and discrete focal nature of an abnormality.