Quantitative Assessment of Acute Intracranial Clot and Collaterals on High-Resolution Magnetic Resonance Imaging

<b><i>Introduction:</i></b> There has been an increasing demand for imaging methods that provide a comprehensive evaluation of intracranial clot and collateral circulation, which are helpful for clinical decision-making and predicting functional outcomes. We aimed to quantitatively evaluate acute intracranial clot burden and collaterals on high-resolution magnetic resonance imaging (HR-MRI). <b><i>Methods:</i></b> We analyzed acute ischemic stroke patients with internal carotid artery or middle cerebral artery occlusion in a prospective multicenter study. The clot burden was scored on a scale of 0–10 based on the clot location on HR-MRI. The collateral score was assigned on a scale of 0–3 using the minimum intensity projection from HR-MRI. Uni- and multivariable logistic regression analyses were performed to assess their correlation with clinical outcome (modified Rankin Scale &gt;2 at 90 days). Thresholds were defined to dichotomize into low- and high-score groups, and predictive performances were assessed for clinical and radiologic outcomes. <b><i>Results:</i></b> Ninety-nine patients (mean age of 60.77 ± 11.54 years) were included in the analysis. The interobserver correlation was 0.89 (95% CI: 0.77–0.95) for the clot burden score and 0.78 (95% CI: 0.53–0.90) for the collateral score. Multivariable logistic regression analysis demonstrated that the collateral score (odds ratio: 0.41, 95% CI: 0.19–0.90) was significantly associated with clinical outcomes. A better functional outcome was observed in the group with clot burden scores greater than 7 (<i>p</i> = 0.011). A smaller final infarct size and a higher diffusion-weighted imaging-based Alberta Stroke Program Early Computed Tomography Score were observed in the group with collateral scores greater than 1 (all <i>p</i> &lt; 0.05). <b><i>Conclusions:</i></b> HR-MRI offers a new tool for quantitative assessment of clot burden and collaterals simultaneously in future clinical practices and research endeavors.