18Fluoroethyl‐l‐tyrosine‐PET in long‐term epilepsy associated glioneuronal tumors

PURPOSE: Long-term epilepsy associated tumors (LEATs) are a frequent cause of drug-resistant partial epilepsy. A reliable tumor diagnosis has an important impact on therapeutic strategies and prognosis in patients with epilepsy, but often is difficult by magnetic resonance imaging (MRI) only. Herein we analyzed a large LEAT cohort investigated by 18fluoroethyl-L-tyrosine-positron emission tomography (FET-PET). METHODS: Thirty-six patients with chronic partial epilepsy and a LEAT-suspect MRI lesion were analyzed by FET-PET using visual inspection and quantitative analysis of standard uptake values (SUV). PET results were correlated with clinical and histopathologic data. RESULTS: FET-PET study was positive in 22 of 36 analyzed lesions and in 14 of 22 histologically verified LEAT lesions. The precise World Health Organization (WHO) tumoral entity was not predicted by FET-PET. Notably, FET uptake correlated strikingly with age at epilepsy onset (p = 0.001). Further correlations were seen for age at surgery (p = 0.007) and gadolinium-contrast enhancement on MRI (p < 0.05). DISCUSSION: FET-PET is a helpful tool for LEAT diagnosis, particularly when MRI readings are ambiguous. FET uptake, which is likely mediated by the l-amino acid transporter (LAT) family, might indicate a principally important biologic property of certain LEATs, since LAT molecules also are involved in cell growth regulation.