Comparison of visual and semiquantitative analysis of 18F-FDOPA-PET/CT for recurrence detection in glioblastoma patients

Amino acid transport imaging with F-18-FDOPA PET is increasingly used for detection of glioblastoma recurrence. However, a standardized image interpretation for F-18-FDOPA brain PET studies has not yet been established. This study compares visual and semiquantitative analysis parameters for detection of tumor recurrence and correlates them with progression-free survival (PFS). One-hundred ten patients (72 male:38 female) with suspected tumor recurrence who underwent F-18-FDOPA PET imaging were studied. PET scans were analyzed visually (5-point scale) and semiquantitatively (lesion-to-striatum- and lesion- to-normal-brain-tissue ratios using both SUVmean and SUVmax). Accuracies for recurrence detection were calculated using histopathology and clinical follow-up for validation. Receiving operator characteristic and Kaplan-Meier survival analysis were performed to derive imaging-based prediction of PFS and overall survival (OS). Accuracies for detection of glioblastoma recurrence were similar for visual (82) and semiquantitative (range, 7782) analysis. Both visual and semiquantitative indices were significant predictors of PFS, with mean lesion-to normal brain tissue ratios providing the best discriminator (mean survival, 39.4 vs 9.3 months; P .001). None of the investigated parameters was predictive for OS. Both visual and semiquantitative indices detected glioblastoma recurrence with high accuracy and were predictive for PFS. Lesion-to-normal-tissue ratios were the best discriminators of PFS; however, none of the investigated parameters predicted OS. These retrospectively established analysis parameters need to be confirmed prospectively.