Cytoskeletal protein breakdown and serum albumin extravasation in MRI DWI-T2WI mismatch area in acute murine cerebral ischemia.

MRI diffusion-weighted imaging (DWI)-FLAIR mismatch is known as predictive of symptom onset within 4.5 h. This study assessed the breakdown of cytoskeletal protein and blood-brain barrier (BBB) in DWI-T2 mismatch. We employed occlusion of middle cerebral artery (MCAO) in C57BL/6 mice. We serially measured MRI including DWI and T2WI. After MRI, we prepared brain sections or samples and examined microtubule-associated protein 2 (MAP2) expression, alpha-fodrin degradation, extravasation of albumin and claudin-5 expression. In permanent or transient MCAO for 45 min, DWI hyperintensities was already found at 60 min without change of T2, showing DWI-T2 mismatch. In permanent MCAO, MAP2 expressions were preserved, and no extravasation of albumin was observed. In transient MCAO, MAP2 immunoreaction was already lost in the lateral part of the striatum. In both models, alpha-fodrin degradation was already detected. At 180 min, T2 hyperintensities appeared, where MAP2 signal was lost and albumin extravasation was found. At 24 h, hyperintensities of DWI and T2WI was found in the whole MCA territory, where MAP2 signal was completely lost with marked albumin extravasation and alpha-fodrin degradation. Immunoreaction for claudin-5 was preserved up to 180 min. DWI-T2 mismatch area may not always indicate intactness of cytoskeletal protein but shows preservation of BBB.