The cerebral vasomotor response in varying CO2 concentrations, as evaluated using cine phase contrast MRI: Flow, volume, and cerebrovascular resistance indices

Purpose: Previous studies have identified that impaired cerebral vasomotor reactivity (VMR) is associated with a higher risk of stroke and transient ischemic attack. This study aims to evaluate VMR by measuring the blood flow waveforms of the supplying arteries and dural sinuses using cine phase contrast MRI (PC MRI) and hypercapnic challenge. Methods: PC MRI flow quantification was performed on an oblique slice approximately perpendicular to the target vessels to include the left (LICA) and right internal carotid artery (RICA), basilar artery (BA), sinus rectus (SR), and superior sagittal sinus (SSS). A total of four PC MRI scans were performed at different CO2 concentrations (room air and 3%, 5%, and 7% CO2). Results: The analyses obtained the flow parameters and cerebrovascular resistance parameters for all five vessels. Results indicated that the vascular resistance indices decreased with increasing CO2 concentration in four vessels (LICA, RICA, BA, and SR). The obtained VMR parameters demonstrated exponential increases with increasing CO2 concentration. Conclusions: Using entire blood flow waveforms, this study applied separate flow dynamics during systolic and diastolic periods to obtain cerebrovascular resistance parameters and extensive flow-related information. It is the first to investigate the cerebrovascular resistance parameters under hypercapnic challenge using cine MRI. This technique could provide a useful tool for clinical application in cerebrovascular disease. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.4754806]