Two‐layered susceptibility vessel sign is associated with biochemically quantified thrombus red blood cell content

Abstract

Background and purpose Better characterization of the thrombus could be useful to determine acute ischemic stroke (AIS) etiology and predict response to thrombolysis and endovascular therapy (EVT). To test the hypothesis that susceptibility vessel sign (SVS) on baseline MRI is related to red blood cell (RBC) content of AIS thrombi, we compared the total hemoglobin content of AIS thrombi retrieved by endovascular therapy (EVT) from patients with or without SVS or two‐layered SVS (TLSVS). Methods Baseline MRI of 84 anterior AIS patients were reviewed by neuro‐radiologists blinded to clinical and biochemical data. Thrombi from these patients were retrieved by EVT and analyzed for hemoglobin content (HbC) by quantitative ELISA and measurement of heme concentration. Results SVS and TLSVS were respectively observed in 85.7% and 50.0% of cases. The median HbC content was 253 µg/mg thrombus (IQR, 177 to 333) and the median heme content was 219 µg/mg thrombus (131 to 264). Thrombus HbC and heme content were highly correlated to thrombus RBC content determined by flow cytometry (r=0,94). Thrombi from patients with TLSVS weighed more (31.1 [16.5 to 68.3] mg vs. 17.7 [11.7 to 33.3] mg; p=0.005) and had a higher HbC content (278 [221 to 331] µg/mg vs. 196 [139 to 301] µg/mg; p=0.010) compared to thrombi from patients without TLSVS. There was no difference in thrombus weight or HbC content according to SVS status. Conclusions Our study shows that TLSVS is significantly associated with a higher thrombus weight and RBC content, as determined by quantitative assays.