Focal lung uptake of 18F-fluorodeoxyglucose (18F-FDG) without computed tomography findings

BACKGROUND: Integrated positron emission tomography/computed tomography (PET/CT) systems represent a major development allowing functional and anatomical information to be acquired in a single examination session and therefore providing a more accurate definition of suspected lesion characteristics. Together with the increasing number of clinical settings in which PET/CT scans have been advocated, however, pitfalls in image interpretation have been reported. METHODS: Four female subjects presenting a focal area of increased F-fluorodeoxyglucose (F-FDG) uptake with no evidence of a corresponding CT abnormality were included in the study. PET/CT scans were performed in all cases after the administration of 5.3 MBq . kg of F-FDG through a venous cannula. RESULTS: Focal high uptake of F-FDG was observed in lung lesions without anatomical counterparts on CT in four female cases. The only common feature to all was the paravenous injection of the radiotracer. CONCLUSION: The lesions detected by PET may be related to distal lung microembolism originating from the site of paravenous injection.