Mapping tissue microstructure of brain white matter in vivo in health and disease using diffusion MRI

TL;DR

This paper presents a diffusion MRI-based biophysical modeling framework that accurately maps brain white matter microstructure, capturing changes during development and disease, with potential for clinical and large-scale research applications.

Contribution

The study introduces a machine learning-based estimator for a multicompartment diffusion model that specifically quantifies axonal microstructure in vivo.

Findings

Captures morphological changes in axons during development, ischemia, and multiple sclerosis

Demonstrates high sensitivity and specificity of the model in clinical conditions

Applicable to large datasets for studying brain development and pathology

Abstract

Diffusion magnetic resonance imaging offers unique in vivo sensitivity to tissue microstructure in brain white matter, which undergoes significant changes during development and is compromised in virtually every neurological disorder. Yet, the challenge is to develop biomarkers that are specific to micrometer-scale cellular features in a human MRI scan of a few minutes. Here we quantify the sensitivity and specificity of a multicompartment diffusion modeling framework to the density, orientation and integrity of axons. We demonstrate that using a machine learning based estimator, our biophysical model captures the morphological changes of axons in early development, acute ischemia and multiple sclerosis (total N=821). The methodology of microstructure mapping is widely applicable in clinical settings and in large imaging consortium data to study development, aging and pathology.