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Post-Traumatic Cerebral Microhemorrhages and their Effects Upon White Matter Connectivity in the Aging Human Brain
Abstract:
Cerebral microbleeds (CMBs), a common manifestation of mild traumatic brain injury (mTBI), have been sporadically implicated in the neurocognitive deficits of mTBI victims but their clinical significance has not been established adequately. Here we investigate the longitudinal effects of post-mTBI CMBs upon the fractional anisotropy (FA) of white matter (WM) in 21 older mTBI patients across the first ~6 months post-injury. CMBs were segmented automatically from susceptibility-weighted imaging (SWI) by leveraging the intensity gradient properties of SWI to identify CMB-related hypointensities using gradient-based edge detection. A detailed diffusion magnetic resonance imaging (dMRI) atlas of WM was used to segment and cluster tractography streamlines whose prototypes were then identified. The correlation coefficient was calculated between (A) FA values at vertices along streamline prototypes and (B) topological (along-streamline) distances between these vertices and the nearest CMB. Across subjects, the CMB identification approach achieved a sensitivity of 97.1% ± 4.7% and a precision of 72.4% ± 11.0% across subjects. The correlation coefficient was found to be negative and, additionally, statistically significant for 12.3% ± 3.5% of WM clusters (p <; 0.05, corrected), whose FA was found to decrease, on average, by 11.8% ± 5.3% across the first 6 months post-injury. These results suggest that CMBs can be associated with deleterious effects upon peri-lesional WM and highlight the vulnerability of older mTBI patients to neurovascular injury.
Insights
Cerebral microbleeds (CMBs) after mild traumatic brain injury (mTBI) can negatively impact white matter integrity in older adults. This study shows CMBs are linked to decreased fractional anisotropy (FA) in white matter within six months post-injury.
Area of Science:
- Neuroimaging
- Neurology
- Traumatic Brain Injury Research
Background:
- Cerebral microbleeds (CMBs) are common after mild traumatic brain injury (mTBI) but their clinical impact on neurocognition remains unclear.
- Understanding the longitudinal effects of CMBs on white matter (WM) integrity is crucial for assessing mTBI outcomes.
Purpose of the Study:
- To investigate the longitudinal association between post-mTBI CMBs and white matter (WM) fractional anisotropy (FA) in older adults.
- To quantify the impact of CMBs on WM integrity in the initial six months following mTBI.
Main Methods:
- Automated segmentation of CMBs from susceptibility-weighted imaging (SWI) using gradient-based edge detection.
- Diffusion MRI (dMRI) and tractography were used to analyze WM structure and its relationship with CMB proximity.
- Correlation analysis between FA values along WM streamline prototypes and topological distances to the nearest CMB.
Main Results:
- The CMB identification method demonstrated high sensitivity (97.1% ± 4.7%) and precision (72.4% ± 11.0%).
- A statistically significant negative correlation was found between CMBs and FA in 12.3% ± 3.5% of WM clusters (p < 0.05, corrected).
- FA in affected WM clusters decreased by an average of 11.8% ± 5.3% over six months post-injury.
Conclusions:
- Post-mTBI CMBs are associated with detrimental effects on peri-lesional white matter integrity.
- Older adults with mTBI exhibiting CMBs may be particularly vulnerable to neurovascular injury and subsequent WM changes.
