In our project we have a shown that the precise targeting of CO2 in combination with BOLD-MRI can be used as a non-invasive “brain stress test” to identify patients at risk for stroke. This technique can be adopted as a routine clinical test in the diagnosis, treatment and prognosis of patients who are at risk of stroke and those with suspected cerebral blood flow abnormalities.”

Cerebrovascular reactivity (CVR), defined as a change in cerebral blood flow in response to a vasoactive stimulus, reflects the vascular reserve capacity of cerebral vessels. Impaired CVR has shown to be an important prognostic marker for stroke. However, no CVR method has been widely adopted to assess the risk for stroke and for clinical management. This project developed a non-invasive method of mapping CVR using a precise targeting of CO2 and Blood oxygen level dependent (BOLD) MRI to identify patients at risk for stroke and to monitor the effect of treatments. In an innovative use of existing techniques, this study showed that the precise targeting of CO2 in combination with BOLD-MRI, provide a feasible, non-invasive and reproducible measure of CVR. This combined technique may be complementary in identifying patients with poor cerebrovascular reserve at risk for stroke and thus constitute a “Brain Stress Test”. This technique can be adapted for routine clinical test in the diagnosis, treatment and prognosis of patients who are at risk of stroke and those with suspected cerebral blood flow abnormalities. This test stands to improve patient care and lower the burden of care on our hospital system.