The usefulness of diffusion-weighted/fluid-attenuated inversion recovery imaging in the diagnostics and timing of lacunar and nonlacunar stroke

Introduction The DWI/FLAIR mismatch is a potential radiological marker for the timing of stroke onset. The aim of the study was to assess if the DWI/FLAIR mismatch can help to identify patients with both lacunar and nonlacunar acute ischemic stroke within 4.5 h of onset. Methods A retrospective study was performed in which the authors analysed data from 86 ischemic lacunar and nonlacunar stroke patients with a known time of symptom onset, imaged within the first 24 h from stroke onset (36 patients <4.5 h, 14 patients 4.5-6 h, 15 patients 6-12 h, and 21 patients 12-24 h). Patients underwent the admission CT and MR scan. The presence of lesions was assessed in correlation with the duration of the stroke. Results The time from stroke onset to neuroimaging was significantly shorter in patients with an ischemic lesion visible only in the DWI (mean 2.78 h, n=24) as compared to patients with signs of ischemia also in other modalities (mean 8.6 h, n=62) (p=0.0001, Kruskal-Wallis ANOVA). The DWI/ FLAIR mismatch was characterised by a global sensitivity of 58 %, specificity 94 %, PPV 87.5 %, and NPV 76 % in identifying patients in the 4.5 h thrombolysis time window. For lacunar strokes (n=20), these parameters were as follows: sensitivity 50 %, specificity 92.8 %, PPV 75 %, and NPV 81.2 %. Conclusions The presence of acute ischemic lesions only in DWI can help to identify both lacunar and nonlacunar stroke patients who are in the 4.5 h time window for intravenous thrombolysis with high specificity.