Effect of mannitol on focal cerebral ischemia evaluated by magnetic resonance imaging.

We have evaluated the effect of mannitol on focal cerebral ischemia using T2-weighted magnetic resonance (MR) imaging and intravoxel incoherent motion (IVIM) MR imaging. The left middle cerebral artery (MCA) was exposed via the transorbital approach in 20 adult cats and occluded just proximal to the origin of the perforating arteries. Seven cats in treatment group received mannitol (0.5 g/kg i.v.) at 0, 6, 12 and 18 hours after MCA occlusion. The other 13 cats received saline and served as controls. Sequential MR coronal images were obtained at 2, 4, 6, and 24 hours after MCA occlusion using a GE Signa (1.5 tesla) system. IVIM MR imaging demonstrated ischemic cerebral injury as a sharply demarcated area at 2 hours after MCA occlusion in control group, while T2-weighted MR imaging failed to show clear evidence of the injury until 2-6 hours. At 24 hours after MCA occlusion, the infarcted area in the mannitol treatment group was 36.9 +/- 7.7% (S.E.M) of the left hemisphere, as compared to 57.3 +/- 5.3% in control group (p < 0.05). Mannitol has beneficial effect on ischemic injury.