Nuclear Medicine Communications The use of Multiparametric 18F-DOPA PET/MRI in post-therapy assessment of patients with gliomas

Purpose: To determine the utility of F-DOPA PET/MRI versus cross-sectional MRI alone in glioma response assessment and identify whether the two techniques demonstrate different tumour features. Methods: F-DOPA PET/MRI studies from 40 patients were analysed. Quantitative PET parameters and conventional MRI features were recorded. Tumour volume was assessed on both PET and MRI. Using DSC-PWI, maps of CBF and CBV were obtained. Within VOIs of tumour features and normal-appearing white matter (NAWM) drawn on MRI, SUVmax, CBF and CBV were recorded. Presence of residual active tumour was assessed by qualitative visual assessment. ROC analysis was performed univariately and on parameter combination to analyse ability to determine presence/absence of disease. Reference standard for presence of viable tissue was biopsy or clinical follow-up. Results: Median SUVmax was 3.4 for low-grade glioma (LGG) and 3.3 for high-grade glioma (HGG). There was a significant correlation between PWI parameters and WHO grade (p<0.001), but no correlation with SUVmax. Median F-DOPA volume was 8216.88 mm for HGG and 6284.94 mm for LGG; MRI volume was 6316.57 mm and 5931.55 mm respectively. SUVmax analysis distinguished enhancing and non-enhancing components from necrosis and NAWM and demonstrated active disease in non-enhancing regions. Visually, the modalities were concordant in 37 patients. Combining the multiparametric PET/MRI approach with all available data enhanced detection of the presence of tumour (AUC 0.99, p<0.01). Conclusion: MRI and F-DOPA are complementary modalities for assessment of tumour burden. Matching F-DOPA and MRI in assessing residual tumour volume may better delineate the radiotherapy target volume.