Improved estimates of cerebral circulation time from BOLD fMRI data using putamen and sagittal sinus signals

Motivation: Cerebral circulation time (CCT) is a metric that provides insight into cerebrovascular health. However, conventional CCT measurements typically require injection of contrast agents, or demonstrate high variability. Goal(s): We propose an improved, contrast-free method to calculate CCT by cross-correlating fMRI signals from the putamen and sagittal sinus. Approach: n 16 healthy adult datasets (8 subjects, 2 sessions), we compared CCT estimates using the internal carotid artery (as proposed in the literature) or putamen as “arterial” references in breath-hold and resting-state data. Results: The putamen ROI provides more reliable CCT estimates, consistent with values from bolus-tracking methods. Impact: A modified analysis of fMRI data provides a robust method to measure cerebral circulation time on a single-subject level. This method may offer an accessible, contrast-free metric of cerebrovascular health for future application in patient populations.