Magnetic resonance elastography of brain tumors

Magnetic resonance elastography (MRE) is a non-invasive imaging technique that can be used to quantify the mechanical properties of brain tissue. Mechanical changes in brain tissue cannot be directly assessed with conventional imaging, whereas MRE provides viscoelastic maps that reveal stiffness differences between healthy brain tissue and benign and malignant tumors. Studies in healthy individuals have demonstrated regional differences in mechanical properties between gray and white matter. Similar variability is observed in brain tumors, where mechanical properties differ with tumor type, grade, histological subtype, and microstructural composition. MRE has been applied to benign brain tumors, including meningiomas, vestibular schwannomas, and pituitary adenomas, to evaluate tumor consistency and support surgical planning. In malignant tumors like glioblastoma, stiffness differences have been linked to changes in extracellular matrix, including fibrous composition, adhesion molecules, and vascular remodeling. As suggested by preclinical research, MRE may also detect treatment-induced mechanical changes and could potentially be used to longitudinally monitor alterations in the tumor microenvironment. This review summarizes current knowledge of MRE in brain tumors, with a focus on stiffness and viscosity related parameters and their biological and structural correlates. The literature reviewed here increasingly supports reduced tissue fluidity and increased mechanical heterogeneity as biomechanical hallmarks of brain tumor aggressiveness.