Growth of the core infarct during the first hours of ischemia onset is not well-understood. We hypothesized that factors other than time from onset of ischemia contribute to core infarct volume as measured by MR imaging.

Prospectively collected clinical and imaging data of consecutive patients with stroke presenting between March 2008 and April 2013 with anterior circulation large-vessel occlusion and MR imaging performed within 6 hours from the time of onset were reviewed. The association of time from onset, clinical, and radiographic features with DWI volume was assessed by using χ² and Mann-Whitney U tests.

Of 91 patients, 21 (23%) underwent MR imaging within 0–3 hours from onset, and 70 (76%), within 3–6 hours. Median MR imaging infarct volume was similar in both timeframes, (24.7 versus 29.4 mL, P = .906), and there was no difference in the proportion of patients with large infarct volumes (≥70 mL, 23.8% versus 22.8%, P = .928). Using receiver operating characteristic analysis, we detected no association between the time from onset and MR imaging infarct volume (area under the curve = 0.509). In multivariate analysis, CTA collaterals (>50% of the territory) (adjusted OR, 0.192; 95% CI, 0.04–0.9; P = .046), CTA ASPECTS (adjusted OR, 0.464; 95% CI, 0.3–0.8; P = .003), and a history of hyperlipidemia (adjusted OR, 11.0; 95% CI, 1.4–88.0; P = .023) (but not time from stroke onset to imaging) were independent predictors of MR imaging infarct volume.

Collateral status but not time from stroke onset to imaging was a predictor of the size of core infarct in patients with anterior circulation large-vessel occlusion presenting within 6 hours from onset.