Voxel-Wise Analysis of Fluoroethyltyrosine PET and MRI in the Assessment of Recurrent Glioblastoma During Antiangiogenic Therapy

OBJECTIVE. In MRI of patients with recurrent glioblastoma, bevacizumab-induced normalization of tumor vascularity can be difficult to differentiate from antitumor effects. The aim of this study was to assess the utility of 18F-fluoroethyl-L-tyrosine (FET) PET in the evaluation of recurrent glioblastoma treated with bevacizumab. SUBJECTS AND METHODS. MRI and FET PET were performed before and after administration of two doses of bevacizumab to 11 patients with recurrent glioblastoma. The ratio between normalized FET uptake at follow-up and baseline of the entire (volume of T2 FLAIR abnormality) and enhancing tumor were assessed for prediction of progression-free survival (PFS) and overall survival (OS). Voxel-wise Spearman correlation between normalized FET uptake and contrast-enhanced T1 signal intensity was assessed and tested as a predictor of PFS and OS. RESULTS. Mean Spearman correlation between FET uptake and contrast-enhanced T1 signal intensity before therapy was 0.65 and after therapy was 0.61 (p =...