Imaging of non-or very subtle contrast-enhancing malignant gliomas with [ 11C]-methionine positron emission tomography

Abstract

In patients with World Health Organization (WHO) grade III glioma with a lack of or minimal (< 1 cm 3) magnetic resonance imaging (MRI) contrast enhancement, the volume of the metabolically active part of the tumor was assessed by [ 11C]-methionine positron emission tomography (MET-PET). Eleven patients with WHO grade III gliomas underwent MET-PET and MRI (contrast-enhanced T 1-and T 2-weighted images). To calculate the volumes in cubic centimeters, threshold-based volume of interest analyses of the metabolically active tumor (MET uptake index ≥ 1.3), contrast enhancement, and the T2 lesion were performed after coregistration of all images. In all patients, the metabolically active tumor volume was larger than the volume of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) enhancement (20.8 ± 18.8 vs 0.29 ± 0.25 cm 3; p