MR mismatch profiles in patients with intracranial atherosclerotic stroke: a comprehensive approach comparing stroke subtypes.

Most clinical trials have focused on the presence of perfusion- and diffusion-weighted imaging (PWI-DWI) mismatch by more than 20%, and different stroke subtypes were lumped together. We hypothesized that intracranial large artery atherosclerotic stroke (IC-LAA) would show different PWI-DWI and magnetic resonance angiography (MRA)-DWI mismatch profiles, compared with other stroke subtypes. Consecutive patients underwent pretreatment multiparametric magnetic resonance imaging for the acute middle cerebral artery infarcts within 6 h of symptom onset. We assessed the difference in the DWI-PWI mismatch ratio, severity of hypoperfusion, and MRA-DWI mismatch among the stroke subtypes. Of 86 patients, 19 (22.1%) had IC-LAA; 42 (48.8%) cardioembolic stroke, 15 (17.4%) extracranial-LAA, and 10 (11.6%) had cryptogenic embolic stroke. Although the volume of the penumbra was not different among the groups, the mismatch ratio was higher (P=0.003) and the severity of hypoperfusion was lower in the IC-LAA group (P=0.001). The MRA-DWI mismatch was more prevalent in the IC-LAA group than in other groups (P<0.001). Collateral grading, assessed in 41 patients, was more likely to be intermediate/excellent in the IC-LAA group (P<0.001). Multivariate testing revealed that a larger mismatch ratio and less severe hypoperfusion, and MRA-DWI mismatch were independently associated with IC-LAA. Our data show that patients with IC-LAA had different mismatch profiles, which were related to better collaterals, compared with other subtypes.