Characterizing Quantitative Magnetization Transfer Maps from an MR-Linac in Regions of Progression in Biopsy-Only Glioblastoma

In biopsy-only glioblastoma patients scanned and treated on a 1.5T MR-Linac, this study quantifies the relationship between the quantitative magnetization transfer (qMT) semi-solid fraction and enhancing regions seen on post-contrast T1-weighted imaging on follow-up MRI scans. Metrics were computed to assess the spatial overlap between low semi-solid fraction regions and enhancing regions. In certain patients, the low semi-solid fraction region at the time of treatment correlated with enhancing region at follow up imaging. Our results suggest reduced semi-solid fraction values precede tumour progression, which could be used for guiding dose adaptation in radiation therapy.