BACKGROUND AND PURPOSE:
Anatomical imaging is a hallmark for visualizing chronic and acute infarcts but provides incomplete information on stroke risk. Respiratory hypercapnic gas challenges show promise for noninvasively assessing hemodynamic function and mapping cerebrovascular reserve capacity, an indicator of how near parenchyma is to exhausting autoregulatory capacity. However, limited safety information exists for this method in high-risk patients with flow-limiting stenosis. This study re…