Objective: Previous studies revealed a close relationship between thrombus length and recanalization rate after intravenous thrombolysis (IVT). However, there is no effective measurement of thrombus length on MRI. As a novel approach, we prospectively adjusted the order of sequence acquisition to obtain delayed gadolinium-enhanced T1 (dGE-T1) and thereby assess thrombus length on dGE-T1 to evaluate its predictive value for recanalization after IVT.
Methods: We reviewed prospectively collected clinical and imaging data from acute ischemic stroke patients with middle cerebral artery (MCA) occlusion who underwent multimodal MRI before and 24 hours after IVT. Perfusion-weighted imaging (PWI) was performed followed by conventional T1. We measured thrombus length on dGE-T1 and examined its association with MCA recanalization.
Results: Of the included 74 patients, the median age was 66 years and 28 (37.8%) were women. Median baseline NIHSS score was 13 (IQR 6-17). Thrombus length was 8.18 ± 4.56 mm on dGE-T1, which was an acceptable predictor for no recanalization (odds ratio 1.196; 95% CI: 1.015 to 1.409; p=0.033), with a receiver-operator characteristic of 0.732 (95% CI: 0.619 to 0.845; p=0.001). The optimal cut-off point was identified at 6.77 mm, which yielded a sensitivity of 77.8% , a specificity of 57.9%, and odds ratio 4.81 (95% CI: 1.742 to 13.292; p=0.002). Moreover, no one achieved recanalization after IVT when length of thrombus exceeded 14 mm on dGE-T1.
Conclusions: The dGE-T1, obtained by simply adjusting scanning order in multimodal MRI protocol, is a useful tool for thrombus length estimation and MCA recanalization prediction after IVT.