Multiphase MR Angiography Collateral Map: Functional Outcome after Acute Anterior Circulation Ischemic Stroke

Abstract

Background: Collateral circulation determines tissue fate and affects treatment result in acute ischemic stroke. A precise method forcollateral estimation in an optimal imaging protocol is necessary to make an appropriate treatment decision for acute ischemic stroke. Purpose: To verify the value of multiphase collateral imaging data sets (MR angiography collateral map) derived from dynamic contrastmaterial-enhanced MR angiography for predicting functional outcomes after acute ischemic stroke. Materials and Methods: This secondary analysis of an ongoing prospective observational study included data from participants withacute ischemic stroke due to occlusion or stenosis of the unilateral internal carotid artery and/or M1 segment of the middle cerebralartery who were evaluated within 8 hours of symptom onset. Data were obtained from March 2016 through August 2018. Thecollateral grading based on the MR angiography collateral map was estimated by using six-scale MR acute ischemic stroke collateral(MAC) scores. To identify independent predictors of favorable functional outcomes, age, sex, risk factors, baseline NationalInstitutes of Health Stroke Scale (NIHSS) score, baseline diffusion-weighted imaging (DWI) lesion volume, site of steno-occlusion,collateral grade, mode of treatment, and early reperfusion were evaluated with multiple logistic regression analyses. Results: One hundred fifty-four participants (mean age 6 standard deviation, 69 years 6 13; 99 men) were evaluated. Younger age(odds ratio [OR], 0.45; 95% confidence interval [CI]: 0.29, 0.70; P,.001), lower baseline NIHSS score (OR, 0.85; 95% CI:0.78, 0.94; P,.001), MAC score of 3 (OR, 27; 95% CI: 4.0, 179; P,.001), MAC score of 4 (OR, 17; 95% CI: 2.1, 134; P =.007), MAC score of 5 (OR, 27; 95% CI: 2.5, 306; P =.007), and successful early reperfusion (OR, 7.5; 95% CI: 2.6, 22; P,.001) were independently associated with favorable functional outcomes in multivariable analysis. There was a linear negative associationbetween collateral perfusion grades and functional outcomes (P<.001). Conclusion: An MR angiography collateral map was clinically reliable for collateral estimation in patients with acute ischemic stroke.This map provided patient-specific pacing information for ischemic progression. (C) RSNA, 2020