Percent Insular Ribbon Infarction Predicts Infarct Growth Rate, Stroke Outcome

Published Date: February 15, 2023
By News Release

Percent insular ribbon infarction (PIRI) complements current stroke outcome predictors, classifying patients with slowly progressive stroke who could benefit from late-window endovascular thrombectomy (EVT), according to a study in the American Journal of Roentgenology.

Noting that PIRI was independently associated with infarct growth rate and 90-day outcome, “PIRI may help identify patients who could benefit from late-window EVT when requiring transfer to EVT-capable centers,” wrote head researcher Robert W. Regenhardt, MD, PhD, from the department of neurology at Massachusetts General Hospital and Harvard Medical School.

Analyzing a previous clinical trial of acute stroke patients untreated with reperfusion therapies from January 2007 to June 2009, Regenhardt et al. reevaluated 31 trial patients (median age, 71 years; 12 female, 19 male) with anterior-circulation large-vessel occlusion who underwent serial MRI examinations. Two neuroradiologists independently scored PIRI on presentation MRI—mild (0-1), moderate (2), severe (3-4)—based upon length ratios of the insula portion showing restricted diffusion to the insula’s total length. A 90-day modified Rankin Scale (mRS) was also obtained.

Ultimately, in multivariable models controlling for age, large-vessel occlusion location, and collateral pattern, PIRI category was a significant independent predictor of presentation-to-48-hour infarct growth rate (β=1.3) and 90-day mRS ≤2 (OR=0.2). Sensitivity and specificity for predicting 90-day mRS ≤2 were 90% and 84% for mild-to-moderate PIRI, versus 70% and 74% for symmetric collateral pattern.

“To our knowledge, the present study is the first to show the PIRI category to be an independent predictor of 90-day mRS <2 in multivariable models,” the authors added.

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