What type of study is this?

This is a Quantitative Study study (also classified as: Experimental Study).

September 17, 2025

Evidence for axonal beading and loss in traumatic brain injury using ultra-high gradient ex vivo diffusion MRI

DSDongsuk SungGeorgia Institute of Technology HLHong‐Hsi LeeHarvard University KCKwok‐Shing ChanHarvard University

Key Points

Axon diameter and intra-axonal fraction were significantly reduced in focal white matter after TBI.
Histological observations of axonal beading and loss correlate with the imaging findings from diffusion MRI.
The study utilized high-resolution ex vivo diffusion MRI on postmortem human brains to analyze axonal changes.
Enhanced imaging capabilities of the Connectome 2.0 MRI scanner facilitate detailed examination of neurodegeneration.

Abstract

Motivation: Understanding the impact of traumatic brain injury (TBI) on axonal microstructure can elucidate neurodegenerative mechanisms and inform novel therapeutics. Goal(s): To investigate post-TBI alterations in axonal microstructure using high-resolution, ultra-high b-value ex vivo diffusion MRI in postmortem human whole-brain specimens. Approach: Four postmortem brains from TBI patients were scanned using 3D diffusion-weighted multi-shot EPI on the Connectome 2.0 MRI scanner. Diffusion data were fitted to the AxCaliber-SMT model to estimate axon diameter, intra-axonal diffusivity, and intra-axonal fraction. Results: Axon diameter and intra-axonal fraction were reduced in focal white matter near cortical contusions, aligning with histopathologically observed features such as axonal beading and loss. Impact: This study leverages the high-performance gradients of the Connectome 2.0 scanner and a state-of-the-art RF coil for ex vivo imaging to create a platform for histopathologic-imaging correlation and elucidate the mechanisms of post-traumatic neurodegeneration.

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