Viscoelasticity of subcortical gray matter structures

Hum Brain Mapp. 2016 Dec;37(12):4221-4233. doi: 10.1002/hbm.23314. Epub 2016 Jul 12.


Viscoelastic mechanical properties of the brain assessed with magnetic resonance elastography (MRE) are sensitive measures of microstructural tissue health in neurodegenerative conditions. Recent efforts have targeted measurements localized to specific neuroanatomical regions differentially affected in disease. In this work, we present a method for measuring the viscoelasticity in subcortical gray matter (SGM) structures, including the amygdala, hippocampus, caudate, putamen, pallidum, and thalamus. The method is based on incorporating high spatial resolution MRE imaging (1.6 mm isotropic voxels) with a mechanical inversion scheme designed to improve local measures in pre-defined regions (soft prior regularization [SPR]). We find that in 21 healthy, young volunteers SGM structures differ from each other in viscoelasticity, quantified as the shear stiffness and damping ratio, but also differ from the global viscoelasticity of the cerebrum. Through repeated examinations on a single volunteer, we estimate the uncertainty to be between 3 and 7% for each SGM measure. Furthermore, we demonstrate that the use of specific methodological considerations-higher spatial resolution and SPR-both decrease uncertainty and increase sensitivity of the SGM measures. The proposed method allows for reliable MRE measures of SGM viscoelasticity for future studies of neurodegenerative conditions. Hum Brain Mapp 37:4221-4233, 2016. © 2016 Wiley Periodicals, Inc.

Keywords: brain; elastography; gray matter; hippocampus; thalamus; viscoelasticity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Biophysical Phenomena
  • Brain / diagnostic imaging
  • Brain / physiology*
  • Elasticity
  • Elasticity Imaging Techniques / methods*
  • Gray Matter / diagnostic imaging
  • Gray Matter / physiology*
  • Humans
  • Image Processing, Computer-Assisted / methods
  • Magnetic Resonance Imaging* / methods
  • Male
  • Nonlinear Dynamics
  • Reproducibility of Results
  • Uncertainty
  • Viscosity
  • Young Adult