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Updated: Jun 3, 2026
Advanced Diffusion Imaging in The Hippocampus of Rats with Mild Traumatic Brain Injury
Published on: August 14, 2019
Diffusion tensor MRI reveals chronic alterations in white matter despite the absence of a visible ischemic lesion on
Ebeline Bihel1, Simon Roussel, Jérôme Toutain
1CERVOxy, Hypoxia and Cerebrovascular Pathophysiology, CI-NAPS UMR-6232, University of Caen, 59, Boulevard Henri Becquerel BP5229, Caen, France 14074.
Background And Purpose:
The impact of stroke on white matter is poorly described in preclinical investigations mainly based on rodents with a low white (WM)/gray matter ratio. Using diffusion tensor imaging, we evaluated WM alterations and correlated them with sensorimotor deficits after stroke in the marmoset, a nonhuman primate that displays a WM/gray matter ratio close to that of humans.
Methods:
Marmosets underwent a transient brain ischemia (3-hour). Eight serial MRI examinations were made during ischemia and up to 45 days after reperfusion. The sensorimotor deficits were evaluated weekly over 45 days. To assess WM alterations, the SD of the angle of the first eigenvector projection was calculated in the cortex and in the internal and external capsules. The fiber-tracking approach was used to measure the number and the length of bundles.
Results:
Changes in the apparent diffusion coefficient and the fractional anisotropy values were similar during the temporal evolution of the lesion in the marmoset model of ischemia to that reported in patients with stroke. Despite an absence of visible lesions on T2-MRI and diffusion tensor imaging at the chronic stage, diffusion tensor MRI evidenced alterations in WM by the increase in the standard deviation of the angle of the first eigenvector projection in the cortex, internal and external capsules, and the decrease in the number of bundles of fibers tracked. The disruption of WM was strongly correlated with the chronic sensorimotor deficits.
Conclusions:
Despite an absence of a visible ischemic lesion at the chronic stage, diffusion tensor MRI revealed disorganization of WM, which probably underlies the persistence of functional deficits.
Insights
Stroke significantly impacts white matter (WM) integrity, even after visible lesions disappear. Diffusion tensor imaging in marmosets revealed chronic WM disorganization, correlating with lasting sensorimotor deficits.
Area of Science:
- Neuroscience
- Radiology
- Primate Models
Background:
- Preclinical stroke research often uses rodents with low white matter (WM)/gray matter ratios, limiting relevance to human stroke.
- White matter alterations post-stroke are not well-characterized in preclinical models.
Purpose of the Study:
- To investigate WM alterations and sensorimotor deficits after stroke in marmosets, a primate model with a human-like WM/gray matter ratio.
- To correlate WM changes with functional deficits using diffusion tensor imaging (DTI).
Main Methods:
- Marmosets experienced transient focal cerebral ischemia.
- Serial MRI (including DTI) and weekly sensorimotor assessments were performed for 45 days post-reperfusion.
- WM integrity was assessed using diffusion metrics and fiber tracking.
Main Results:
- DTI findings in marmosets mirrored human stroke evolution regarding apparent diffusion coefficient and fractional anisotropy.
- Chronic DTI revealed WM alterations (increased eigenvector angle standard deviation, decreased fiber bundle count) despite absent T2-MRI lesions.
- WM disruption strongly correlated with persistent sensorimotor deficits.
Conclusions:
- DTI can detect chronic WM disorganization after stroke in marmosets, even without visible lesions on conventional MRI.
- This WM disorganization likely explains persistent functional deficits observed in the chronic stroke phase.
