20 Updates on Magnetic Resonance Imaging assessment of tumour MicrOStructure in GlioblastomA: A cross-sectional study (The MIMOSA Study)

Abstract The MIMOSA (Magnetic Resonance Imaging assessment of tumour MicrOStructure in GlioblastomA) study is recruiting patients with a presumed diagnosis of glioblastoma (GBM) pre-operatively to receive advanced diffusion-weighted magnetic-resonance-imaging (DW-MRI) using the CONNECTOM microstructure MRI-scanner at Cardiff University Brain Research Imaging Centre (CUBRIC). This provides a novel non-invasive tool to explore the tumour and peritumoral zone (PTZ) over time, characterising tissue microstructure and the tumour microenvironment in patients with GBM before and after treatment. We aim to provide insight to enable improved assessment and prediction of treatment response in patients with GBM. Methods From May 2025- Feb 2026 21 patients with radiologically-suspected GBM identified from South Wales Neuro-oncology MDT completed CONNECTOM and MR-elastography scans pre-surgery. Imaging data are processed using a fully-automated analysis pipeline incorporating quality control and voxel-wise microstructural modelling to characterise tumour and peritumoral tissue. Sequences include VERDICT and HARDI, providing diffusion and microstructure sensitivity, improving characterization of heterogeneity, and supporting robust quantitative comparisons across subjects and repeat time points at 3 and 6-months. Results 16/21 patients have had GBM subsequently diagnosed on histology (1 meningioma, 1 oligodendroglioma, 1 poorly-differentiated carcinoma, 2 awaiting histology). 4/21 patients have completed all follow-up scans, with 1/21 withdrawing at 3 months. Initial analysis confirms high data-quality and feasibility of extracting quantitative microstructural metrics from advanced DW-MRI across tumour and PTZ. Interim analysis of pre-operative scans demonstrates microstructural heterogeneity within the tumour and extension into the PTZ. Patient feedback demonstrates that the long scanning protocol is well tolerated. Conclusions We demonstrate that recruitment of suitable patients is feasable, and the target of 40 patients within 2 years is achievable. Analysis of post-operative imaging will aim to reveal changes in tumour and PTZ over time.