Decreased tissue stiffness in glioblastoma by MR elastography is associated with increased cerebral blood flow

[EN] Purpose: Understanding how mechanical properties relate to functional changes in glioblastomas may help explain different treatment response between patients. The aim of this study was to map differences in biome-chanical and functional properties between tumor and healthy tissue, to assess any relationship between them and to study their spatial distribution. Methods: Ten patients with glioblastoma and 17 healthy subjects were scanned using MR Elastography, perfusion and diffusion MRI. Stiffness and viscosity measurements G' and G '', cerebral blood flow (CBF), apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in patients' contrast-enhancing tumor, necrosis, edema, and gray and white matter, and in gray and white matter for healthy subjects. A regression analysis was used to predict CBF as a function of ADC, FA, G' and G ''. Results: Median G' and G' ' in contrast-enhancing tumor were 13% and 37% lower than in normal-appearing white matter (P < 0.01), and 8% and 6% lower in necrosis than in contrast-enhancing tumor, respectively (P < 0.05). Tumors showed both inter-patient and intra-patient heterogeneity. Measurements approached values in normalappearing tissue when moving outward from the tumor core, but abnormal tissue properties were still present in regions of normal-appearing tissue. Using both a linear and a random-forest model, prediction of CBF was improved by adding MRE measurements to the model (P < 0.01). Conclusions: The inclusion of MRE measurements in statistical models helped predict perfusion, with stiffer tissue associated with lower perfusion values. Grant Support: We gratefully acknowledge support from the European Union's Horizon 2020 Programme: ERC Grant Agreement No. 758657-ImPRESS, Research and Innovation Grant Agreements No. 668039-FORCE and Marie Sklodowska-Curie grant agreement (No 844646-GLIOHAB), South-Eastern Norway Regional Health Authority (Grant Agreement No. 2017073, 2013069 and 2021057), The Research Council of Norway FRIPRO (Grant Agreement No. 261984), the National Institutes of Health R21 grant (Grant Agreement No. EB030757), and the German Research Foundation (DFG, SCHR 1542/1-1). Svensson, SF.; Fuster García, E.; Latysheva, A.; Fraser-Green, J.; Nordhoy, W.; Darwish, OI.; Hovden, IT... (2022). Decreased tissue stiffness in glioblastoma by MR elastography is associated with increased cerebral blood flow. European Journal of Radiology. 147:1-11. https://doi.org/10.1016/j.ejrad.2021.