Atlas of confounding factors in head and neck PET/CT imaging.

Purpose: Interpretation of positron emission tomography/computed tomography (PET/CT) studies in the head and neck region is challenging due to the complex anatomy and nonspecific physiologic and inflammatory FDG uptake. We present an atlas of common confounding factors encountered at our institution.

Materials And Methods: We present whole-body fluorodeoxyglucose (FDG) PET/CT studies of 20 patients with various confounding factors in the head and neck.

False-positive indium 111 pentetreotide scan for recurrent meningioma due to radiation fibrosis.

A patient with recurrent meningioma in the right frontal lobe, treated with resection and radiation, had a routine magnetic resonance imaging scan that was suspicious for recurrent disease. Follow-up Octreoscan showed moderately increased focal uptake in same region, compatible with recurrence of meningioma; however, the histopathology was consistent with radiation fibrosis. There are reported cases of uptake on Octreoscans at other sites of the body due to chronic inflammation, but only one other case has been reported in the brain.