Taking MR elastography (MRE) to the microscopic scale (µMRE)

Microscopic resolution MR Elastography (μMRE) could be useful not only in vivo, but also in vitro for assessing the development and differentiation of engineered tissues prior to implantation, as well as for assessing the 3 dimensional viscoelastic properties of biopsied specimens. Using MRE to determine viscoelastic properties of sub-millimeter tissue structure requires that both the MR image and the vibratory shear waves be viewed with tens of microns resolution. Thus, μMRE requires larger imaging gradients, faster gradient switching times and higher acoustic excitation frequencies than clinical MRE. Developments and difficulties faced in pushing the resolution limits of μMRE are reviewed, including challenges in high frequency shear wave actuation, high field image acquisition and reconstruction, and tissue modeling.