MR Elastography of the Brain: In healthy subjects and patients with glioblastoma

Abstract

In the pursuit of treatment strategies for brain tumors, advanced MRI techniques are used to investigate the properties of tumors. Cancer is known to affect the biomechanical properties of tissues, such as stiffness. MR elastography (MRE) is an imaging technique that can measure stiffness noninvasively. In this thesis, we perform MRE in the brain of healthy subjects and patients with glioblastoma, the most aggressive type of brain tumor. We find that MRE is a robust technique for measuring brain tissue stiffness and that it can help us understand the properties of brain tumors. In patients with glioblastoma, we find that the biomechanical properties measured by MRE differ between tumor tissue and the healthy brain. Consistent with the infiltrative nature of the disease, abnormal values can extend beyond the tumor borders that are visible on conventional MR images. Low tissue stiffness is moreover associated with higher blood flow. MRE imaging of glioblastoma can demonstrate tumor heterogeneity before surgery. We show that tumor regions of increased stiffness were associated with extracellular matrix reorganization using RNA sequencing of tissue biopsies. Notably, biopsies identified as stiff by MRE were associated with a gene expression signal that correlates with shorter survival of glioblastoma patients.