Leptomeningeal anastomosis and early ischemic lesions on diffusion-weighted imaging in male murine focal cerebral ischemia.

Leptomeningeal anastomosis is a key factor for determining early ischemic lesions on diffusion-weighted imaging (DWI) in human stroke. However, few studies have validated this relationship in an experimental model. This study sought to clarify the involvement of leptomeningeal anastomosis in early ischemic lesions using a murine model. Adult male C57BL/6 mice were subjected to unilateral common carotid artery (CCA) occlusion or sham surgery. Seven or 14 days later, the middle cerebral artery (MCA) was occluded for 45 min. In the first experiment, the leptomeningeal collaterals were visualized using magnetic resonance imaging (MRI) DWI. In the second experiment, DWI was performed immediately after MCA occlusion, and the infarct sizes were determined 24 hr after recirculation. Unilateral CCA occlusion reduced the size of early ischemic lesions, enlarged the pial vessel diameter, and mitigated infarct size. The relationship between the DWI lesion size and pial vessel diameter was significant (r = 0.84, p < 0.01). The association between infarct size and DWI lesion size was also significant (r = 0.96, p < 0.01). In conclusion, involvement of the collateral circulation in early ischemic lesions was evident in the murine model. Both MRI and evaluation of leptomeningeal anastomosis could be used to develop a novel strategy targeting enhancement of the collateral circulation.