Microstructural changes in memory-related brain regions of stroke-free patients with middle cerebral artery occlusion as revealed by diffusion spectrum imaging.

We used diffusion spectrum imaging (DSI) and 3-dimensional arterial spin labeling to investigate microstructural and perfusion changes in memory-related brain regions in stroke-free patients with middle cerebral artery (MCA) occlusion. Forty-nine patients with unilateral MCA occlusion, 11 with bilateral MCA occlusion, and 30 healthy controls underwent 3.0 T MRI. Quantitative anisotropy (QA), restricted diffusion imaging (RDI), and fractional anisotropy (FA) were analyzed in memory-related gray matter regions and fiber tracts. The ratio of cerebral blood flow (CBF) and QA in the affected temporal lobe compared to the contralateral side is referred to as relative CBF (rCBF) and relative QA (rQA). Pearson correlation analysis was conducted to assess the relationship between rCBF and rQA in the temporal lobe. In unilateral MCA occlusion patients, paired t-tests revealed significantly lower QA and RDI in lesion-side regions of interest (ROIs) compared with contralateral ROIs. For healthy controls, bilateral hemispheric values were averaged, and independent t-tests were used for group comparisons. Patients with unilateral MCA occlusion showed broadly reduced QA and RDI in bilateral ROIs relative to controls, with more severe abnormalities on the lesion side. A moderate correlation between temporal lobe rCBF and rQA indicated that cerebral hypoperfusion may contribute to microstructural alterations. These findings demonstrate that stroke-free patients with unilateral MCA occlusion exhibit subclinical microstructural damage in memory-related brain regions and connected white matter tracts.