Background and purpose: We aimed to investigate the role of perfusion MRI parameters (TTP: time to peak, CBF: cerebral blood flow, CBV: cerebral blood volume) as a prognostic factor for the risk of stroke recurrence or cardiovascular outcome in patients with transient ischemic attack (TIA) or minor stroke.
Methods: We retrospectively reviewed TIA or minor stroke patients who underwent our stroke MRI protocol (DWI, perfusion MRI, and MRA) in a consecutively collected stroke registry. Primary outcome was nonfatal stroke recurrence and secondary outcome was cardiovascular composite outcome. Multivariate analysis was used to examine the association of perfusion MRI parameters and angiographic findings with the risk of stroke recurrence and cardiovascular event.
Results: Of the 326 patients who met inclusion criteria, we identified 15(4.6%) nonfatal strokes and 25(7.7%) cardiovascular composite events during the first 1 year after the index TIA or minor stroke. The presence of regional delayed perfusion on TTP maps (p=0.002) and regional hyperperfusion on CBV maps (p<0.001) were associated with recurrent stroke. In MRA images, concomitant stenosis of the intracranial arteries and/or extracranial carotid arteries was associated with cardiovascular events (p=0.009). Using multivariate cox proportional hazard analysis, presence of regional hyperperfusion on CBV remained an independent predictor of recurrent stroke (HR 10.82, 95% CI 4.19-38.67, p<0.001) and cardiovascular event (HR 6.30, 95% CI 2.67-18.25, p<0.001). The AUC of the CBV maps was also greater than other parameters for the prediction of stroke recurrence (AUC=0.701, 95% CI 0.54-0.86) and cardiovascular composite outcome (AUC=0.628, 95% CI 0.50-0.76).
Conclusions: Increased CBV on perfusion MRI, representing the hemodynamic status of postischemic hyperperfusion, could be more useful than other perfusion parameters in predicting poor prognosis of TIA or minor stroke patients.