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Early Identification of Ischemic Stroke With DWI-FLAIR Mismatch

Acute lesions ID'd with DWI, but not FLAIR, likely to be in time for safe, effective thrombolysis

WEDNESDAY, Oct. 5 (HealthDay News) -- The mismatch between acute ischemic lesion visibility on diffusion-weighted magnetic resonance imaging (MRI) (DWI), and fluid-attenuated inversion recovery (FLAIR) MRI (DWI-FLAIR mismatch) can identify patients with acute ischemic lesions within 4.5 hours of symptom onset, according to a study published online Oct. 5 in The Lancet Neurology.

Götz Thomalla, M.D., from the Universitätsklinikum Hamburg-Eppendorf in Germany, and colleagues investigated whether DWI-FLAIR mismatch in acute ischemic lesion visibility could detect patients with acute ischemic lesions within the recommended time window for thrombolysis. Clinical and MRI data were collected from 543 patients (mean age, 66 years; median National Institutes of Health Stroke Scale score of 8) between 2001 and 2009. Predictive values of DWI-FLAIR mismatch were calculated to identify patients within 4.5 to 6 hours of symptom onset. Potential confounding covariates were identified by multivariate regression analysis.

The investigators identified acute ischemic lesions on DWI in 95 percent of patients, and on FLAIR in 50 percent of patients, with moderate interobserver agreement for acute ischemic lesion visibility on FLAIR imaging. The sensitivity, specificity, and positive and negative predictive values for DWI-FLAIR mismatch identifying patients within 4.5 hours were 62, 78, 83, and 54 percent, respectively. Significant independent predictors of lesion visibility on FLAIR imaging were longer time to MRI, lower age, and larger DWI lesion volume.

"Patients with an acute ischemic lesion detected with DWI but not with FLAIR imaging are likely to be within a time window for which thrombolysis is safe and effective," the authors write.

Several authors disclosed financial ties to the medical device and pharmaceutical industries.

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