New Pulse Sequence Combining Diffusion MRI and MR Elastography (dMRE)

Introduction: MRE measures tissue stiffness, which reflects the underlying structural organization of cells, extracellular matrix, and capillaries. Diffusion MRI measures the apparent diffusion coefficient (ADC), which describes the random motion of water molecules in both the intraand the extra-cellular compartments. Both MRE and diffusion MRI are used for detecting diseases in soft biological tissues such as the brain, liver, and other internal organs. Therefore, the combination of MRE and diffusion MRI may provide complementary information on the changes of tissue cellularity and structure associated with pathology. Several studies have shown the potential of combining MRE with diffusion MRI for assessing liver diseases, and for measuring the anisotropic viscoelasticity of gel phantoms and human brains. These studies, however, used separate acquisitions of MRE and diffusion that prolong the imaging protocols. Here, we introduce a new pulse sequence, Diffusion-MRE (dMRE), that is capable of encoding diffusion attenuation and MRE wave motion simultaneously.