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

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.

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.

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.

The lesions detected by PET may be related to distal lung microembolism originating from the site of paravenous injection.