Background: Infarct volume is an important surrogate marker for assessing the efficacy of acute stroke therapies. We studied the evolution of acute stroke lesions on FLAIR images over time following endovascular therapy in a subgroup of patients (n=35) from the DEFUSE 2 study.
Methods: FLAIR images were acquired both post-revascularization (median 12h after symptom onset) and at day 5. Patients were separated into two groups based on the degree of reperfusion achieved on Tmax>6s perfusion imaging (>90% vs. <90%). After co-registration and signal normalization, lesion volumes and signal intensity were assessed in both initial infarct (lesion visible after revascularization), and recruited infarct (additional lesion visible lesion on day 5).
Results: All 35 patients had FLAIR lesion growth between post-revascularization and day 5. Median infarct growth was significantly larger in patients with 90% (8.12ml, p=0.003). In the initial infarct, signal intensity did not change between post-revascularization and day 5 in the >90% reperfused group, while it increased in the <90% reperfused group (p = 0.01). In the recruited infarct, signal increased significantly in both groups between post-revascularization and day 5 (p < 0.0001).
Conclusions: Compared with patients who have <90% reperfusion, patients with >90% reperfusion have significantly less infarct growth between post- endovascular revascularization and day 5. Therefore, reductions in ischemic lesion growth attributable to reperfusion therapies are likely to be more apparent at day 5 compared to early post-revascularization.