Evaluation of White Matter Integrity Utilizing the DELPHI (TMS-EEG) System

Area of Science:

• Neuroscience
• Biomedical Engineering
• Neurology

Background:

• White matter (WM) integrity is crucial for brain function.
• Stroke and traumatic brain injury (TBI) can cause significant WM damage.
• Current methods for assessing WM damage have limitations.

Purpose of the Study:

• To evaluate brain white matter (WM) fibers connectivity damage in stroke and traumatic brain injury (TBI) subjects.
• To assess the efficacy of direct electrophysiological imaging (DELPHI) using transcranial magnetic stimulation (TMS)-evoked potentials (TEPs).
• To correlate DELPHI measures with diffusion tensor imaging (DTI) metrics of WM microstructure.

Main Methods:

• 123 participants (53 with WM pathologies: 39 stroke, 14 TBI; 70 controls) underwent DELPHI and DTI scans.
• DELPHI evaluated TMS-EEG-evoked potentials for brain network analysis.
• DTI quantified WM microstructure using fractional anisotropy (FA).

Main Results:

• DELPHI showed significant differences between healthy and stroke/TBI groups (balanced accuracy 0.81, AUC 0.88).
• A regression model predicted WM microstructure changes (FA) based on DELPHI measures.
• Highest correlations were found for fibers near stimulation sites (e.g., frontal corpus callosum, anterior internal capsule).

Conclusions:

• TMS-evoked response features correlate with WM microstructure changes in stroke and TBI.
• A multidimensional DELPHI approach combined with supervised learning is a strong indicator of WM abnormalities.
• DELPHI offers a promising tool for assessing WM integrity in neurological conditions.