![]() With DWI it is possible to identify severely ischemic brain regions within minutes to hours after stroke onset. The new MR techniques of diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) are rapidly becoming integral parts of the diagnostic workup in the acute stroke setting. Functionally, more moderate perfusion deficits (TTP delays ≥4 and <6 s) appear to also contribute to the acute clinical deficit. The volume of the regions with TTP delays of ≥4 s correlated better with ESS ( r=−0.88, P<0.001) than other PWI (or DWI) volumes, which indicated that a TTP delay of ≈4 s might be the threshold for functional impairment of brain tissue.Ĭonclusions-Only patients with severe perfusion deficits in the PWI/DWI mismatch (TTP delays of ≥6 s) are at high risk of lesion enlargement. Lesions increased in 9 of 12 patients (75%) in whom the area with TTP delay ≥6 s was larger than the DWI lesion, but they increased in only 1 of 8 (12.5%) of the remaining patients, in whom the area with a TTP delay ≥6 s was smaller than the DWI lesion. A TTP delay of ≥6 s in the mismatch region was found to be associated with lesion enlargement between the initial and follow-up MRI scans. Results-In 80% of patients the acute DWI lesion was surrounded by regions with abnormal TTP delays (PWI>DWI lesion). With PWI, the volumes of regions with “time-to-peak” (TTP) delays of ≥2, 4, 6, 8, and 10 seconds were measured these volumes were compared with the acute DWI lesion volumes, final infarct size, and ESS score. Methods-Twenty patients with nonlacunar ischemic stroke were imaged with DWI, PWI, and conventional MRI within 24 hours of symptom onset and after 1 week in addition, the European Stroke Scale (ESS) score was recorded. During the first hours of stroke evolution, the regions with abnormal perfusion are typically larger than the DWI lesions, and this mismatch region has been suggested to be “tissue at risk.” The aim of this study was to evaluate the PWI/DWI mismatch region in acute stroke patients and find parameters indicative of both infarct progression and functional impairment. Customer Service and Ordering Informationīackground and Purpose-Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) are relatively new MR techniques increasingly used in acute stroke.Stroke: Vascular and Interventional Neurology.Journal of the American Heart Association (JAHA).Circ: Cardiovascular Quality & Outcomes.Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB). ![]()
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