Abstract
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Objectives Although the usefulness of FDG-PET in the diagnosis of prostate cancer has been regarded as limited, abnormal incidental foci of hypermetabolism in the prostate gland may sometimes be identified during routine interpretation of FDG-PET/CT scans. This study evaluated the yield of whole-body FDG PET/CT for the detection of unexpected FDG-avid prostate cancers in patients being evaluated by PET/CT for known or suspected malignances.
Methods Reports from whole-body FDG PET/CT scans from January 2010 to April 2011 were reviewed, and 4354 patients who had been scanned for known or suspected malignant lesions were included in this study. FDG-avid focal lesions in the prostate gland newly discovered on PET/CT were interpreted as suggestive of unexpected prostate cancer. These abnormalities were compared with the final diagnosis obtained from the medical records, including pathologic reports.
Results PET-positive lesions suggestive of prostate cancers were found in 129 (3.0%) of 4354 patients. The pathological confirmation of the suspected lesion was obtained in 15 patients. Among them, the lesions were proven to be malignant in 13 patients (0.3%) and benign in 2 patients. Although the final diagnosis of the suspected lesion has not yet been pathologically resolved in the remaining patients, most of the FDG-avid foci were assumed as physiological FDG accumulation in the urethra or urinary reflux in the prostate gland when compared with other imaging modalities.
Conclusions Whole-body PET/CT detected unexpected FDG-avid prostate cancers in at least 0.3% of patients. Our data suggests FDG-avid focal prostate lesion incidentally found on FDG-PET/CT warrants further evaluation because of the substantial rate of malignancy