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Original research
Opercular Index Score: a CT angiography-based predictor of capillary robustness and neurological outcomes in the endovascular management of acute ischemic stroke
  1. Alexander Copelan1,
  2. Monzer Chehab1,
  3. Waleed Brinjikji2,
  4. Zachary Wilseck3,
  5. David F Kallmes2,
  6. Jeffery Wilseck1
  1. 1 Department of Radiology and Diagnostic Imaging, Beaumont Health System, Royal Oak, Michigan, USA
  2. 2 Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
  3. 3 Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan, USA
  1. Correspondence to Dr Alexander Copelan, Beaumont Health System, Diagnostic Radiology Administration-2CT, 3601 W, 13 Mile Rd, Royal Oak, MI 48073, USA; alexander.copelan{at}


Background Many CT angiography (CTA) collateral scoring systems are either subjective or complex and time consuming.

Objective To evaluate the correlation between a CTA collateral scoring system—the Opercular Index Score (OIS)—with neurological outcomes at 90 days following endovascular treatment for acute ischemic stroke (AIS) secondary to large vessel occlusion.

Methods Fifty-five patients with AIS due to distal internal carotid artery, M1, or proximal M2 occlusions who underwent endovascular treatment were included. OIS was retrospectively calculated from CTA images, reconstructed from CT perfusion imaging, as the ratio of opacified M3 opercular branches in the Sylvian fissure on the unaffected side to those on the stroke side and dichotomized into favorable (OIS≤2) and poor (OIS>2). The ability of OIS to predict good neurological outcomes (modified Rankin Scale score ≤2 at 90 days) was assessed using sensitivity, specificity, and area under the curve (AUC) with receiver operating characteristic analysis.

Results Thirty-five patients had a favorable OIS and 20 patients had a poor OIS. Patients with favorable OIS had an 80.0% (n=28) rate of good neurological outcomes compared with 15.0% (n=3) of patients with a poor OIS (p<0.0001). On multivariate logistic regression analysis adjusting for baseline National Institutes of Health Stroke Scale score, OIS, and device used, favorable OIS was the only variable independently associated with good neurological outcome (OR=17.2, 95% CI 3.8 to 104.3) and demonstrated a sensitivity of 90.3% and specificity of 70.8% with an AUC of 0.822.

Conclusions OIS is a simple and practical non-invasive scoring system that can be used to predict collateral robustness and good neurological outcome among patients with AIS undergoing endovascular treatment.

  • CT Angiography
  • Stroke
  • Thrombectomy

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  • Contributors AC designed the data collection tools, monitored data collection for the whole trial, and was primary author of the draft and revisions of the manuscript. He is guarantor. MC assisted with data collection, contributed to the introduction and discussion, and assisted with the initial draft of the manuscript. WB contributed to data collection, wrote and conducted the statistical analysis, and contributed to the discussion section of the manuscript. ZW assisted in the literature review and contributed to the discussion section of the manuscript. DFK contributed to data collection and assisted with the discussion section of the manuscript. JW was the primary senior author, proposed the idea for the study, assisted in the data collection and the editing of the manuscript.

  • Competing interests None declared.

  • Ethics approval Institutional review board at both institutions.

  • Provenance and peer review Not commissioned; externally peer reviewed.