Selection Of Magnetic Resonance Imaging Or Computed Tomography Before Mechanical Thrombectomy For Acute Ischemic Stroke

Introduction: Evaluation of ischemic core and penumbra by magnetic resonance imaging (MRI) or computed tomography (CT) is useful in determining the indication for mechanical thrombectomy (MT) for acute ischemic stroke, however, it is still uncertain which imaging modality is superior. In this study, we compared the clinical outcomes after MT by imaging modality in the K-NET registry (Kanagawa intravenous and endovascular treatment of acute ischemic stroke registry). Methods: The K-NET registry (January 2018 to December 2021) is a Japanese multicenter prospective registry study of patients treated with Intravenous thrombolysis with recombinant tissue plasminogen activator (alteplase), endovascular treatment of cerebral infarction, or both for acute ischemic stroke. Patients who were enrolled by December 2020 and underwent MT were included in the study. We compared the favorable outcome at 90 days (modified Rankin Scale [mRS] score 0-2 or mRS shift [prestroke - day 90] = 0) between the MRI group and the CT alone group. Results: Of the 2348 patients enrolled in K-NET, 1763 underwent MT. Median age was 77 years (70-84) and 745 (42.2%) were female. There were 1311 patients in the MRI group and 452 in the CT group. There were no notable differences in patient characteristics. Despise the time from presentation to imaging was significantly shorter in the CT group (MRI: 14 minutes [9-21]; CT: 8 minutes [4-15]; P<0.001), there was no difference in time from presentation to recanalization. The rate of favorable outcome at 90 days was higher in the MRI group (MRI: 46.4%; CT: 40.7%; P=0.03). There was no difference in outcome between the two groups within 6 hours of onset, however, after 6 hours, the MRI group had a better outcome (MR 41.1%; CT: 28.2%; P=0.05). Compared due to SSS-TOAST classification, the MRI group had a better outcome in atherothrombotic patients (MRI group: 53.8%; CT group: 40.3%; P=0.04), while other subtypes of stroke did not show any difference. Conclusions: MRI imaging before MT was associated with favorable outcome. In addition, patients after 6 hours of onset and those with atherothrombotic disease had more favorable outcomes in the MRI group, suggesting that MRI may be useful as an imaging modality before thrombus retrieval in these patients.