Diffusion Tensor Imaging Reveals Elevated Diffusivity of White Matter Microstructure that Is Independently Associated with Long-Term Outcome after Mild Traumatic Brain Injury: A TRACK-TBI Study

Journal of Neurotrauma, 2022 · DOI: 10.1089/neu.2021.0408 · Published: October 1, 2022

Simple Explanation

This study used diffusion tensor imaging (DTI) to examine white matter changes in patients with mild traumatic brain injury (mTBI). The goal was to see how these changes relate to long-term recovery. The researchers found that in mTBI patients, certain measures of white matter microstructure were elevated compared to controls shortly after the injury. Some of these differences decreased over time. Importantly, the degree of these early white matter changes was linked to how well patients recovered six months after the injury, suggesting that DTI could be a useful tool for predicting outcomes.

Study Duration

6 Months

Participants

391 mTBI patients and 148 controls

Evidence Level

Not specified

Key Findings

1
Patients with mTBI showed higher levels of axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) in white matter compared to controls at both two weeks and six months post-injury.
2
Global white matter AD and MD at two weeks post-injury were independently associated with six-month incomplete recovery (GOSE <8 vs = 8).
3
The association of two-week AD with six-month GOSE was consistently stronger for the left-sided tract than the right.

Research Summary

This multi-center study examined white matter changes after mTBI using DTI, finding widespread higher levels of AD, MD, and RD, and lower levels of FA, at two weeks after trauma compared with matched controls. The changes in MD, and especially AD, partially resolve by six months post-injury, whereas those of FA and RD do not. Higher AD and MD at two weeks are both independently associated with better long-term outcome, even after accounting for demographic, clinical, and CT factors.

Practical Implications

Biomarker for Clinical Trials

DTI can serve as an imaging biomarker for patient selection and to monitor treatment response in clinical trials, especially those targeting pathophysiological mechanisms.

Prognostic Tool

DTI has utility as an imaging biomarker for patient selection and to monitor treatment response in clinical trials.

Understanding Pathophysiology

The findings contribute to understanding the dynamic pathophysiological processes, such as neuroinflammatory vasogenic edema and secondary axonal degeneration, in mTBI.

Study Limitations

1
DTI assumes an ellipsoidal model with a single ﬁber orientation per voxel; hence, all DTI metrics have issues in WM regions with crossing ﬁbers.
2
Only about half of enrolled patients with mTBI could be imaged with research MRI scans.
3
Approximately 20% of imaged patients had to be excluded, largely because of motion artifacts.

Your Feedback

Was this summary helpful?

Back to Neurology