Does SWI Clot Length Predict Intracranial Atherosclerosis-related Large Vessel Occlusion in Acute Stroke?

Background: Prediction of etiology of acute large vessel occlusion (LVO) will help to tailor mechanical thrombectomy (MT) approach. Objective: ICAD-related LVO is focal and likely to have a short clot length, which can be measured on susceptibility-weighted imaging (SWI). Materials and Methods: This is a single-center study based on a retrospective analysis of acute LVO stroke treated by MT between April 2018 and June 2021. ICAD- related LVO was diagnosed if the final angiography showed fixed focal stenosis or re-occlusion after MT. Demographic and clinical characteristics, imaging features, SWI clot sign, SWI clot length and morphology of retrieved clots were compared between the ICAD-related LVO and Thromboembolic LVO. Results: Ninety-eight patients underwent MT for acute LVO stroke. Eighty-two patients were included in the analysis among which 26 were grouped under ICAD-related LVO, and 56 were grouped under thromboembolic etiology based on the final angiogram. SWI clot length >9.1 mm with a branching pattern of occlusion was seen in thromboembolic LVO whereas a clot length < 9.1 mm with a truncal pattern of occlusion was seen in ICAD LVO (p<0.05). SWI Clot length cut off of 9.17 mm predicted the etiology of occlusion with a sensitivity of 62.5% (95% CI, 35.4–84.8) and specificity of 93.2% (95% CI, 81.3-98.6). Conclusion: A short clot length (<9.1 mm) predicts ICAD related LVO as probable etiology. Along with other validated imaging parameters for predicting etiology, it helps to tailor mechanical thrombectomy.