Negative 18F-FET PET/CT in Brain Metastasis Recurrence: a Teaching Case Report.

Abstract

\n Positron emission tomography (PET) using O-(2-[18F]fluoroethyl)-L-tyrosine (18F-FET) positron emission tomography (PET) has been shown to be a useful tool for differentiating radiation therapy outcomes either brain metastasis recurrence or radiation necrosis. We present the case of a female with known metastatic brain lesion with suspicion of tumor recurrence on follow-up MRI 16 months after radiosurgery. 18F-FET PET was indicative of radiation necrosis. Due to the patient s medical history, the discrepancy between brain MRI and the PET/CT results, surgical biopsies were decided, which were positive for brain metastasis recurrence. Diagnosis of metastasis recurrence may be challenging also on 18F-FET PET/CT. In case of discrepancies between MRI and PET/CT results, false-negative 18F-FET PET/CT is still possible and should lead to careful follow-up or biopsy.