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Updated: Apr 28, 2026
Advanced Diffusion Imaging in The Hippocampus of Rats with Mild Traumatic Brain Injury
Published on: August 14, 2019
Microinfarct disruption of white matter structure: a longitudinal diffusion tensor analysis
Eitan Auriel1, Brian L Edlow1, Yael D Reijmer1
1From the J. Philip Kistler Stroke Research Center, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
Objective:
To evaluate the local effect of small asymptomatic infarctions detected by diffusion-weighted imaging (DWI) on white matter microstructure using longitudinal structural and diffusion tensor imaging (DTI).
Methods:
Nine acute to subacute DWI lesions were identified in 6 subjects with probable cerebral amyloid angiopathy who had undergone high-resolution MRI both before and after DWI lesion detection. Regions of interest (ROIs) corresponding to the site of the DWI lesion (lesion ROI) and corresponding site in the nonlesioned contralateral hemisphere (control ROI) were coregistered to the pre- and postlesional scans. DTI tractography was additionally performed to reconstruct the white matter tracts containing the ROIs. DTI parameters (fractional anisotropy [FA], mean diffusivity [MD]) were quantified within each ROI, the 6-mm lesion-containing tract segments, and the entire lesion-containing tract bundle. Lesion/control FA and MD ratios were compared across time points.
Results:
The postlesional scans (performed a mean 7.1 ± 4.7 months after DWI lesion detection) demonstrated a decrease in median FA lesion/control ROI ratio (1.08 to 0.93, p = 0.038) and increase in median MD lesion/control ROI ratio (0.97 to 1.17, p = 0.015) relative to the prelesional scans. There were no visible changes on postlesional high-resolution T1-weighted and fluid-attenuated inversion recovery images in 4 of 9 lesion ROIs and small (2-5 mm) T1 hypointensities in the remaining 5. No postlesional changes in FA or MD ratios were detected in the 6-mm lesion-containing tract segments or full tract bundles.
Conclusions:
Asymptomatic DWI lesions produce chronic local microstructural injury. The cumulative effects of these widely distributed lesions may directly contribute to small-vessel-related vascular cognitive impairment.
Insights
Small asymptomatic brain infarctions detected by diffusion-weighted imaging (DWI) cause lasting white matter damage. These lesions may contribute to cognitive decline associated with small-vessel disease.
Area of Science:
- Neuroimaging
- Neurology
- White Matter Diseases
Background:
- Small asymptomatic lesions are increasingly detected using diffusion-weighted imaging (DWI).
- The long-term microstructural impact of these lesions on white matter is not well understood.
Purpose of the Study:
- To evaluate the local effect of small asymptomatic infarctions on white matter microstructure.
- To use longitudinal diffusion tensor imaging (DTI) to assess changes over time.
Main Methods:
- Subjects with probable cerebral amyloid angiopathy and DWI lesions underwent serial MRI.
- Regions of interest (ROIs) in lesioned and contralateral healthy white matter were analyzed.
- DTI parameters (fractional anisotropy, mean diffusivity) were quantified before and after lesion detection.
Main Results:
- A significant decrease in FA and increase in MD ratios in lesioned ROIs was observed post-lesion.
- No visible changes were seen on conventional MRI, though small T1 hypointensities appeared in some lesions.
- No microstructural changes were detected in larger white matter tract segments or bundles.
Conclusions:
- Asymptomatic DWI lesions induce chronic local microstructural injury in white matter.
- The cumulative effect of these lesions may contribute to vascular cognitive impairment.
