Early Post-Thrombectomy MRI Markers: Temporal Evolution and Association With Reperfusion and Clinical Outcome

A significant proportion of patients with ischemic stroke treated with endovascular therapy (EVT) do not achieve favorable clinical outcomes despite successful recanalization. Identifying patients who may benefit from adjunctive therapies is a priority. We hypothesized that incomplete reperfusion is associated with evolution of imaging markers on early post-EVT MRI and clinical outcome.

Patients who underwent attempted EVT for anterior circulation large vessel occlusion (LVO) stroke and had early (<6 hours) and planned 24-hour MRI were enrolled in the Guiding neUroprotection After Reperfusion to prevent Damage in acute ischemic Stroke study. Imaging markers were evaluated by consensus, blinded to clinical data except for the LVO target. Frequencies of imaging markers and lesion patterns, and their associations with reperfusion and clinical outcome were reported. Good clinical outcome was defined as modified Rankin Scale (mRS) score 0-2 at 30 days.

A total of 207 patients were included: median age 67 years, 53% female, 47% Black or African American, admission NIH Stroke Scale (NIHSS) score 16 (10-21), preadmission mRS score 0 (0-1), and onset-to-triage time 192 minutes. Patients with incomplete reperfusion (54%) had higher apparent diffusion coefficient (ADC) and perfusion volumes after EVT and, by 24 hours, exhibited higher rates of lesion growth and edema. Thirty-five percent of those with early incomplete reperfusion had a mixed perfusion pattern at 24 hours. A stable lesion pattern was seen in only 12% of all patients at 24 hours. Early complete reperfusion was associated with lower NIHSS scores (8 vs 13, p = 0.011) and increased early neurologic improvement (ENI, 66% vs 43%, p = 0.002), at 24 hours. Absence of mixed signal on ADC (odds ratio 3.01, p = 0.015, 95% CI 1.24-7.33) remained a significant predictor of good clinical outcome at 30 days, even after adjusting for age, admission NIHSS score, and ENI.

This observational study systematically characterized MRI markers at serial follow-up early after EVT. The heterogeneous and dynamic evolution observed during the hours and days after EVT in most patients suggests further opportunity to intervene, with early incomplete reperfusion and reperfusion injury as prognostic differentiators. Our findings can serve as a roadmap for designing future clinical trials to develop adjunctive therapies targeting these imaging markers.