Absent middle cerebral artery flow predicts the presence and evolution of the ischemic penumbra

Objectives: In acute ischemic stroke the pattern of a perfusion-imaging (PI ) lesion larger than the diffusion-weighted imaging (DWI) lesion may be a m arker of the ischemic penumbra. We hypothesized that acute middle cerebral artery (MCA) occlusion would predict the presence of presumed "penumbral" p atterns (PI > DWI), ischemic core evolution, and stroke outcome. Methods: E choplanar PI, DWI, and magnetic resonance angiography (MRA) were performed in 26 patients with MCA territory stroke. Imaging and clinical studies (Can adian Neurological Scale, Barthel Index, and Rankin Scale) were performed w ithin 24 hours of onset and repeated at days 4 and 90. Results: MCA flow wa s absent in 9 of 26 patients. This was associated with lar ger acute PI and DWI lesions, greater PI/DWI mismatch, early DWI lesion expansion, larger f inal infarct size, worse clinical outcome (p < 0.01) and provided independe nt prognostic information (multiple linear regression analysis, p < 0.05). Acute penumbral patterns were present in 14 of 26 patients. Most of these p atients (9 of 14) had no MCA flow, whereas all nonpenumbral patients (PI le ss than or equal to DWI lesion) had MCA flow (p < 0.001). Penumbral-pattern patients with absent MCA flow had greater DWI lesion expansion (p < 0.05) and worse clinical outcome (Rankin Scale score, p < 0.05). Conclusions: Abs ent MCA flow on MRA predicts the presence of a presumed penumbral pattern o n acute PI and DWI and worse stroke outcome. Combined MRA, PI, and DWI can identify individual patients at risk of ischemic core progression and the p otential to respond to thrombolytic therapy beyond 3 hours.