Basilar artery thrombus magnetic susceptibility for cardioembolic stroke identification

The susceptibility vessel sign (SVS) on magnetic resonance imaging (MRI) in the middle cerebral artery is a reliable biomarker for cardioembolic ischemic stroke. As for the basilar artery (BA), the magnetic susceptibility-related image signs, the quantitative evaluation of the corresponding thrombus, and their prediction of cardioembolism require further study. This study aimed to assess thrombus susceptibility-related image characteristics using susceptibility-weighted imaging (SWI) and quantitative susceptibility mapping (QSM) MRI in acute BA occlusion and analyze their associations with cardioembolic ischemic stroke. A total of 41 consecutive acute ischemic stroke patients with BA occlusion within 48 h of onset were recruited. A three-dimensional (3D) multi-echo scan on a 3.0T MRI scanner was applied to all participants, and the quantitative susceptibility value of the BA thrombus was computed using QSM. The presence and diameter of SWI SVS in patients with cardioembolic stroke were not significantly different from those with other etiologies. While BA thrombus's susceptibility in patients with cardioembolic stroke was significantly higher than that in patients with non-cardioembolic stroke (0.42±0.09 vs. 0.22±0.11 ppm, P<0.001). Receiver operating characteristic (ROC) curve analysis showed that the optimal cutoff value for the QSM susceptibility of BA thrombus in the identification of cardioembolic stroke was 0.33 ppm, with sensitivity, specificity, positive predictive value, and negative predictive value of 81.8% (95% CI: 48.2% to 97.7%), 81.3% (95% CI: 63.6% to 92.8%), 60.0% (95% CI: 40.9% to 76.5%), and 92.9% (95% CI: 78.6% to 97.9%), respectively. Magnetic susceptibility in BA thrombus could discriminate cardiogenic embolism from other stroke subtypes, thus becoming a novel biomarker of cardiogenic stroke in acute BA occlusion.