Metabolic Imaging of Cerebral Gliomas: Spatial Correlation of Changes in O-(2-18F-Fluoroethyl)- L-Tyrosine PET and Proton Magnetic Resonance Spectroscopic Imaging

The aim of this study was to determine the spatial correlation of O-(2-18F-fluoroethyl)-L-tyrosine (18F-FET) uptake and the con-centrations of choline (Cho), creatine (Cr), and total N-acetylas-partate (tNAA) determined with proton magnetic resonance spectroscopic imaging (1H MRSI) in cerebral gliomas for the multimodal evaluation of metabolic changes. Methods: 18F-FET PET and 2-dimensional 1H MRSI were performed in 15 patients with cerebral gliomas of World Health Organization (WHO) grades II–IV. PET and 1H MRSI datasets were coregistered by use of mutual information. On the basis of their levels of 18F-FET uptake, 4 different areas in a tumor (maximum, strong, moderate, and low 18F-FET uptake) were defined on PET slices as being congruent with the volume of interest in the 1H MRSI experiment. 18F-FET uptake in lesions was evaluated as tumor-to-brain ratios. Metabolite concentrations for Cho, Cr, an