PET/CT: Focal lung uptake of 18F-fluordeoxyglucose on PET but no structural alterations on CT

Abstract The combination of positron emission tomography (PET) and computed tomography (CT) in a single device (PET/CT) provides a powerful diagnostic tool opening new horizons for imaging diagnosis. In order to correctly interpret PET/CT studies, knowledge of the biodistribution of 18 F-fluorodeoxyglucose (FDG), the physiological variants as well as the pitfalls, including the artefacts which may be found is necessary. We report four cases performed during the follow up diagnosis of an oncology study performed with 18 F-FDG-PET/CT. This study showed focal uptake in the lung parenchyma in the PET study in all the cases, with no structural lesions being found on CT scan. Radiotracer extravasation in three of these patients and a recent change in the injection protocol used suggest that an artefact was responsible for these discrepancies.