Introduction and Hypothesis: We evaluated the ability of mixed grading system based on thrombus burden and collateral status assessed by multiphase computed tomography (MPCT) as a predictor of outcome after recanalization therapy.
Methods: Eighty-six consecutive patients who underwent MPCT for acute M1 middle cerebral artery occlusion within 6 hours of symptom onset were included. Collateral status to the occluded MCA territory was classified as follows: grade 1, no collaterals; grade 2, slow collaterals with persistence of defect; Grade 3, slow but complete collateral; grade 4, rapid complete collateral. A grade of 1-2 was designated as poor, 3-4 as good collateral flow. Short clot segment was defined as contrast filling defect length on MPCT < 1 centimeter. We divided patients into 3 groups based on collateral status and clot segment length: good collateral with short clot segment (N=29), good collateral with long clot segment (N=34), poor collateral (N=23).
Results: Clinical characteristics were not different between 3 groups. Good functional outcome (3 months modified Rankin scale scores ≤ 2) and major neurologic improvement (1 day NIHSS score improved to 0 or 1 point or > 8 points decrease from baseline) were more frequent for short clot segment group and good collateral group than poor collateral group. In logistic regression, after adjusting other variables, good collateral and short clot segment were independent predictors for good functional outcome compared poor collateral (good collateral: OR 12.117, p=0.013; short clot segment with good collateral: OR 44.418, p=0.003). Similarly, the major neurologic improvement was significantly related with good collateral and short segment group. (good collateral: OR 8.903, p=0.41; short clot segment with good collateral: OR 40.430, p=0.006)
Conclusions: Short clot segment and good collateral flow assessed with MPCT were useful additional markers predicting clinical outcomes after recanalization therapy.