Standard‐space atlas of the viscoelastic properties of the human brain

Abstract

Standard anatomical atlases are common in neuroimaging because they facilitate data analyses and comparisons across subjects and studies. The purpose of this study was to develop a standardized human brain atlas based on the physical mechanical properties (i.e., tissue viscoelasticity) of brain tissue using magnetic resonance elastography (MRE). MRE is a phase contrast-based MRI method that quantifies tissue viscoelasticity noninvasively and in vivo thus providing a macroscopic representation of the microstructural constituents of soft biological tissue. The development of standardized brain MRE atlases are therefore beneficial for comparing neural tissue integrity across populations. Data from a large number of healthy, young adults from multiple studies collected using common MRE acquisition and analysis protocols were assembled (N = 134; 78F/ 56 M; 18-35 years). Nonlinear image registration methods were applied to normalize viscoelastic property maps (shear stiffness, μ, and damping ratio, ξ) to the MNI152 standard structural template within the spatial coordinates of the ICBM-152. We find that average MRE brain templates contain emerging and

Robustness of MR Elastography in the Healthy Brain: Repeatability, Reliability, and Effect of Different Reconstruction Methods

“…This study presents both absolute and normalized measurements. Because stiffness has been shown to vary with age and sex, normalizing within each subject is even more critical with a more heterogeneous subject population 31,32 …”

Calibration of a Heterogeneous Brain Model Using a Subject-Specific Inverse Finite Element Approach

“…The implementation of brain material heterogeneity in the CAB-20MSym template model was derived from the MRE134 template image ( Hiscox et al, 2020 ). This template was constructed using MRE data from 134 healthy, young adults (18–35 years, 78F/56M) using common MRE acquisition and data processing protocols ( Hiscox et al, 2020 ).…”

“…The implementation of brain material heterogeneity in the CAB-20MSym template model was derived from the MRE134 template image ( Hiscox et al, 2020 ). This template was constructed using MRE data from 134 healthy, young adults (18–35 years, 78F/56M) using common MRE acquisition and data processing protocols ( Hiscox et al, 2020 ). To adapt the MRE134 template, originally defined in MNI152 space with 2 mm isotropic voxels, it was first non-linearly registered to the CAB-20MSym template space using ANTs non-linear registration ( Avants et al, 2008 ).…”

“…The goal of this study is to calibrate and verify a heterogenous FE brain model by leveraging experimental datasets reporting (1) MRE-derived material properties ( Hiscox et al, 2020 ), (2) high rate, in situ , brain displacements measured from human cadaveric specimens using sonomicrometry ( Alshareef et al, 2020a ), and (3) low rate, in vivo , brain strain measured from human volunteers using tagged magnetic resonance imaging (tMRI; Knutsen et al, 2020 ). Material parameters for the model were developed in three phases.…”

“…Material parameters for the model were developed in three phases. First, stiffness data from an MRE template image (average of 134 subjects; Hiscox et al, 2020 ) was used to define the relative stiffness gradient throughout the brain model. Second, the linear stiffness parameter was calibrated using low-displacement cases from the Alshareef et al (2020a) dataset and verified using brain strain data from the in vivo tMRI dataset.…”