Acute DWI volume is a strong imaging predictor of favorable outcomes in patients with acute stroke and treated with mechanical thrombectomy.

Background: Infarct volume on diffusion-weighted imaging (DWI) is a promising imaging marker for clinical outcomes in patients with acute stroke treated with mechanical thrombectomy (MT), but its predictive value has not been well evaluated, especially in consecutive patients. The present study aimed to elucidate the relationship between infarct volume and its change and favorable functional outcomes in consecutive patients with acute stroke who underwent MT.

Method: Of patients with consecutive acute stroke who underwent MT from September 2014 through December 2019, those who were pre-morbidly independent were enrolled. Infarct volume on DWI was measured at admission (DWI) and 24 h after admission (DWI) with semi-automated imaging software. Infarct growth (IG) was calculated as the difference between DWI and DWI. Factors associated with a favorable outcome (mRS score 0-2) 3 months after stroke onset were assessed by multivariable analyses. Model performance was evaluated with the C-statistic.

Results: A total of 251 patients (165 male [66 %], median age 75 [IQR 67-81] years, median NIHSS score 15 [7-21]) were enrolled in the present study. Multivariable logistic regression analysis showed that DWI (OR 0.74, 95 % CI 0.62-0.87 for every 10-mL increment) and IG (0.74, 0.62-0.88 for every 10-mL increment) were independently and negatively associated with a favorable outcome. These associations were observed in patients with diverse vessel occlusions. Adding DWI or IG to the conventional predictors of favorable outcomes improved predictive accuracy (p < 0.05).

Conclusion: DWI infarct volume 24 h after admission and IG can be strong imaging predictors of favorable outcomes after MT.