Abstract
Asymmetric hypointensity of cerebral veins on susceptibility-weighted imaging has been shown to indirectly reflect tissue hypoxia after cerebral ischemia. We therefore investigated whether patients with prominent asymmetry of the cerebral veins on SWI and a relatively small diffusion-weighted imaging lesion (SWI-DWI mismatch), representing the presence of salvageable tissue, were more likely to benefit from thrombolytic therapy. We conducted a retrospective study of the anterior circulation of patients with ischemic stroke with SWI/DWI acquired before thrombolysis. The asymmetry index was defined as the ratio of cerebral vein voxel count between the ischemic and normal hemisphere on the SWI phase map. We defined SWI-DWI mismatch as an asymmetry index score of ≥1.75 with a DWI lesion volume of ≤25 mL. Favorable outcome was defined as modified Rankin Scale 0-2 at 3 months. Univariate and multivariate logistic regression analyses were used to examine the association between the mismatch profile and favorable outcome. Fifty-four patients undergoing thrombolytic treatment were enrolled in this study. The rate of favorable outcome was significantly higher among patients with baseline SWI-DWI mismatch compared with those without (78% versus 44%; adjusted odds ratio, 6.317; 95% CI, 1.12-35.80; P = .037). Patients with SWI-DWI mismatch were also more likely to have a favorable outcome from reperfusion (91% versus 43%, P = .033) or recanalization (100% versus 40%, P = .013). The accuracy of SWI-DWI mismatch for predicting favorable outcome was higher than that of perfusion-diffusion mismatch (63% versus 48.1%). The presence of SWI-DWI mismatch may identify patients with ischemia who would benefit from early reperfusion therapy.
Highlights
BACKGROUND AND PURPOSEAsymmetric hypointensity of cerebral veins on susceptibility-weighted imaging has been shown to indirectly reflect tissue hypoxia after cerebral ischemia
ABBREVIATIONS: AI ϭ asymmetry index; TIMI ϭ Thrombolysis in Myocardial Infarction; Tmax ϭ time-to-peak of the residue function
Intravenous thrombolysis with recombinant tissue plasminogen activator is a proved treatment for acute ischemic stroke within 4.5 hours of symptom onset.[1]
Summary
We conducted a retrospective study of the anterior circulation of patients with ischemic stroke with SWI/DWI acquired before thrombolysis. Our predefined inclusion criteria for MR imaging– guided intravenous thrombolysis included the following: 1) age older than 18 years; 2) stroke symptoms lasting Ͼ1 hour; 3) an NIHSS score of Ն4 or NIHSS score of Ͻ4 but with aphasia or severe dysarthria; 4) the absence of intracranial hemorrhage confirmed by SWI; 5) onset-to-treatment time within 4.5 hours and fulfilling standard clinical criteria, or onset-to-treatment time of 4.5– 6 hours with large-vessel occlusion on MR angiography and fulfilling the perfusion-diffusion mismatch criteria: DWI lesion of Յ70 mL, a perfusion lesion to diffusion lesion volume ratio of Ն1.2, and an absolute difference between perfusion and diffusion lesion volume of Ͼ10 mL.[16] Standard IV thrombolysis exclusion criteria were applied according to current guidelines.[17] We prospectively obtained baseline demographic and clinical information. All procedures were conducted according to the principles expressed in the Declaration of Helsinki
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