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Background and purpose: Magnetic resonance imaging quantitative T2* mapping has shown reliable identification of thrombus red blood cell content in vitro. The thrombus composition has been in vivo, associated with outcomes after endovascular therapy for acute ischemic stroke. We aim to analyze the red blood cell content of thrombi retrieved from patients with large vessel occlusions in relation to the thrombus-T2* relaxation time in magnetic resonance imaging. Material and methods: Consecutive acute ischemic stroke patients treated by endovascular therapy were scanned with an magnetic resonance imaging quantitative T2* mapping sequence. Quantitative histologic evaluations of red blood cell content were performed. A linear regression assessed the association between vascular risk factors, comorbidities, antithrombotic drugs intake, baseline National Institutes of Health Stroke Scale (NIHSS), intravenous thrombolysis before endovascular therapy, time between onset and groin puncture, patient's outcome at 3 months, magnetic resonance imaging quantitative T2* mapping results, and the red blood cell content of thrombi. The correlation between the mean thrombus-T2* relaxation time and red blood cell content was assessed by calculating the Pearson correlation coefficient. Results: Among 31 thrombi, 16 were "Fibrin rich" and 15 "red blood cell dominant." The median red blood cell content was 39 (range, 0–90; interquartile range, 37). The median (interquartile range) thrombus-T2* relaxation time was shorter in "red blood cell dominant" thrombi (21, interquartile range 6) than in "Fibrin rich" thrombi (24, interquartile range 7), without significant difference (p = 0.15), as shown in the Box plot. An inverse correlation between thrombus-T2* relaxation time and red blood cell content was found, with a correlation coefficient of −0.41 (95% CI, −0.67 to −0.08, p = 0.02). Conclusion: Our study shows that a shorter thrombus-T2* relaxation time is related to a higher red blood cell content within in vivo thrombi. [ABSTRACT FROM AUTHOR]

Background: Fluid attenuated inversion recovery (FLAIR) vascular hyperintensity (FVH) document slowed vascular flow at the level and after the occlusion site patients with acute ischemic stroke (AIS). We aimed to assess the accuracy of FVH for the confirmation and location of a large vessel occlusion (LVO). Methods: Three radiologists reviewed the FLAIR sequence of the admission MRI exam of patients with suspected AIS at a single academic center. Readers were provided with the main clinical deficit with National Institute of Health Stroke Severity score and were asked to identify and locate an LVO when appropriate. Kappa coefficients were calculated for agreement along with diagnosis performances of FVH to recognize and locate an LVO with digital subtracted angiography (DSA) as gold standard. Results: Among 125 patients screened with MRI for a suspected AIS, 96 (81%) were diagnosed with AIS and 47 (38%) patients had an anterior LVO of whom 25 (20%) had a DSA for mechanical thrombectomy. Kappa coefficients for intra- and inter-readers were good to excellent. Overall, the sensitivity and the specificity of the FVH to predict an anterior LVO was 0.98 (95% confidence interval [CI]: 0.94–1) and 0.86 (95% CI: 0.79–0.96), respectively, while PPV and NPV were 0.87 (95% CI: 0.85–0.95) and 0.98 (0.97–1), respectively. FVH also showed good to excellent accuracy for identifying M1 and M2 versus internal carotid artery occlusion site. Conclusion: We found that FVH demonstrated excellent diagnostic performances for the identification of LVO and its level with good to excellent reproducibility. This MRI radio marker of occlusion provides additional arguments and may speed-up the detection of potential candidates for MT. [ABSTRACT FROM AUTHOR]