Background Clinical response immediately after revascularisation therapy differs among patients. Although reperfusion is the deciding factor with respect to this dramatic response to revascularisation therapy, the influence of pre- and post-treatment diffusion–perfusion status on the speed and degree of recovery are unknown.

Methods Consecutive stroke patients who were eligible for revascularisation therapy underwent serial diffusion–perfusion MRI. Tmax perfusion maps were generated, and stroke severity and recovery were assessed up to day 90. The relationship of diffusion and perfusion lesion indices with the speed and degree of recovery were evaluated.

Results 69 patients (42 men; aged 66.3±15.9 years) were included; National Institutes of Health Stroke Scale (NIHSS) score was 13.3±6.4 points. 19 received intravenous tissue plasminogen activator (tPA) and 50 received endovascular therapy with/without intravenous tPA. Early dramatic improvement (NIHSS score reduction of ≥40% within 24 h) was observed in 24 (34.8%) patients. Among the other 45 patients, 18 (40%) showed good outcomes (modified Rankin score 0–2 at day 90), suggesting delayed recovery. The volume of post-treatment perfusion delay was similar between the early and delayed recovery groups (p=0.329) but smaller than in the non-responders group (p<0.05). Multivariate testing revealed that smaller post-treatment perfusion delay volumes were independently associated with both early dramatic improvement and delayed recovery. In addition, initial diffusion weighted imaging lesion volume was smaller in the former than in the latter (p=0.029) and was independently associated with early dramatic recovery.

Conclusions A significant proportion of patients with a lack of early dramatic improvement (40%) showed delayed recovery. Both pretreatment infarct volume and post-treatment reperfusion correlated with the degree and speed of recovery.