Stroke: Highlights of Selected Articles

In this study, the authors hypothesized that in acute ischemic strokes, more permeable intracranial arterial thrombi (as opposed to less permeable thrombi) could be associated with better clinical outcomes and improved response to intra-arterial therapy. The authors examined the attenuation increase on computed tomographic angiography (CTA) and void fraction, using combination of noncontrast computed tomography and CTA, as a surrogate for contrast penetration in thrombi and thrombus permeability, and correlated these to clinical outcomes. The study examined 184 patients from the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR-CLEAN) study. To measure thrombus attenuation, CTA images were aligned by automated algorithm to noncontrast computed tomography. Regions of interest were constructed to measure the attenuation within the thrombus and contralateral artery. Thrombus perviousness was estimated by (1) the increase in the attenuation of the thrombus on the CTA when compared with the noncontrast computed tomography and (2) the thrombus void fraction (ratio of the thrombus void volume over the total thrombus volume). The primary outcome measure was favorable outcome at 90 days (modified Rankin Scale score, ≤2), and secondary outcomes included modified Rankin Scale, early recanalization, and final infarct volume. The median thrombus intensity increase was 7.6 HU (interquartile range, 0.30–17.4) for unfavorable outcome and 15.3 HU (interquartile range, 7.5–27.8) for a favorable outcome (P<0.001). The median void fraction was 4.2% (interquartile range, 0.2–10.5) for unfavorable outcome and 10.2% (interquartile range, 4.5–17.9) for favorable outcome (P<0.001). Sensitivity analyses showed that a thrombus was considered pervious when the intensity increase on CTA was larger than the threshold of 10.9 HU, with 64% specificity and sensitivity, and when the thrombus void fraction was 6.5% (66% specificity; 62% sensitivity). The odds ratio for favorable outcome of a patient with a pervious thrombus were 3.2 (95% confidence interval [CI], 1.7–6.4) for increased attenuation and 3.3 (95% CI, 1.7–6.3) for thrombus void fraction. Furthermore, thrombus perviousness was significantly associated with the final score on the modified Rankin Scale score, recanalization rates, and final infarct volume. These measures may, thus, prove useful for early prognostication and treatment selection of patients with acute ischemic stroke. See p 732.