Introduction: Resting cerebral blood flow (CBF) and perfusion measures have been used to determine brain health. Studies showing variation in resting CBF with age and fitness level using different imaging approaches have produced mixed findings. We assess the degree to which resting CBF measures through transcranial Doppler (TCD) and arterial spin labeling (ASL) MRI provide complementary information in older and younger, fit and unfit cohorts. Methods: Thirty-five healthy volunteers (20 younger: 24 ± 7y; 15 older: 66 ± 7y) completed two experimental sessions (TCD/MRI). Aging and fitness effects within and between imaging modalities were assessed. Results: Middle cerebral artery blood velocity (MCAv, TCD) was lower and transit time (MRI) slower in older compared with younger participants (p <.05). The younger group had higher gray matter cerebral perfusion (MRI) than the older group, albeit not significantly (p =.13). Surprisingly, fitness effects in the younger group (decrease/increase in MCAv/transit time with fitness, respectively) opposed the older group (increase/decrease in MCAv/transit time). Whole cohort transit times correlated with MCAv (r=−0.63; p <.05), whereas tissue perfusion did not correlate with TCD measures. Conclusion: TCD and MRI modalities provide complementary resting CBF measures, with similar effects across the whole cohort and between subgroups (age/fitness) if metrics are comparable (e.g., velocity [TCD] versus transit time [MRI]).
Bibliographical noteFunding Information:
We would like to thank Dr Matthew Ryan for assessing the ECGs. We would also like to thank the Birmingham University Imaging Centre (BUIC) for generously providing additional MRI scanning time to support this study. This work was supported by The Physiological Society [Research Grant #444, 2014], a University of Birmingham PhD studentship and a University of Birmingham University of Nottingham Strategic Collaboration Grant.
This work was supported by The Physiological Society [Research Grant #444, 2014], a University of Birmingham PhD studentship, and a University of Birmingham–University of Nottingham Strategic Collaboration Grant
© 2021 The Authors. Brain and Behavior published by Wiley Periodicals LLC
- MRI functional
- cerebral blood flow
- cerebral hemodynamics
- multimodal imaging
- transcranial Doppler sonography
ASJC Scopus subject areas
- Behavioral Neuroscience