Brain

MR elastography of the brain is an emerging technique that can noninvasively estimate brain tissue stiffness, which is usually reported as the shear modulus. It relies on using motion-encoding gradients synchronized to an externally applied vibration, to measure shear wave propagation through the brain parenchyma. This data is then analyzed, typically offline, to produce cerebral elastograms – maps of brain stiffness. In recent years, more patient-friendly vibration transducers have been developed, enabling clinical studies in human patient groups. A number of degenerative brain disorders have been observed to be associated with lower brain stiffness, although studies tend to be relatively small, and few have been independently confirmed by other research groups to date. Due to wide variation in the implementations and analysis approaches used in brain MR elastography, users must take care when interpreting brain MRE data. There is a need for large scale multi-site studies using brain MRE in clinical brain disorders.