The Utility of Cerebrovascular Reactivity MRI in Brain Rehabilitation: A Mechanistic Perspective

• Type of Material: Article
• Authors: Venkatagiri Krishnamurthy, Emory University; Justin D Sprick, Emory University; Lisa Krishnamurthy, Emory University; Jolie D Barter, Emory University; Aaminah Turabi, Atlanta VAMC; Ihab Hajjar, Emory University; Joe Nocera, Emory University
• Language: English
• Date: 2021-03-17
• Publisher: FRONTIERS MEDIA SA
• Publication Version: Final Published Version
• Copyright Statement: © 2021 Krishnamurthy, Sprick, Krishnamurthy, Barter, Turabi, Hajjar and Nocera.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3389/fphys.2021.642850
• Title of Journal or Parent Work: FRONTIERS IN PHYSIOLOGY
• Volume: 12
• Start Page: 642850
• End Page: 642850
• Grant/Funding Information: This work was supported by the Center grant award (5I50RX002358) sponsored by Veterans Health Administration. VK received funding from the Veterans Affairs Rehabilitation Research & Development Service (USA) grant 1IK2RX002934. JN received funding from the Veterans Affairs Rehabilitation Research & Development Service (USA) grant 1I01RX002825. LK received funding from the Veterans Affairs Rehabilitation Research & Development Service (USA) grant IK1 RX002629. IH received funding from NIH grants K24AG062786, R01AG049752, and RF1AG057470.
• Keywords: integrative physiology; rehabilitation; MEDIATED DILATION; ALZHEIMERS-DISEASE; MRI; Science & Technology; mechanism; Life Sciences & Biomedicine; cerebrovascular reactivity; PHYSICAL-ACTIVITY; cerebrovascular disease; MILD COGNITIVE IMPAIRMENT; ARTERIAL STIFFNESS; CARBON-DIOXIDE; CARDIOVASCULAR RISK-FACTORS; CEREBRAL-BLOOD-FLOW; AEROBIC EXERCISE; Physiology; VASCULAR ENDOTHELIAL FUNCTION; aging
• Research Categories: Health Sciences, Rehabilitation and Therapy

Abstract

Cerebrovascular control and its integration with other physiological systems play a key role in the effective maintenance of homeostasis in brain functioning. Maintenance, restoration, and promotion of such a balance are one of the paramount goals of brain rehabilitation and intervention programs. Cerebrovascular reactivity (CVR), an index of cerebrovascular reserve, plays an important role in chemo-regulation of cerebral blood flow. Improved vascular reactivity and cerebral blood flow are important factors in brain rehabilitation to facilitate desired cognitive and functional outcomes. It is widely accepted that CVR is impaired in aging, hypertension, and cerebrovascular diseases and possibly in neurodegenerative syndromes. However, a multitude of physiological factors influence CVR, and thus a comprehensive understanding of underlying mechanisms are needed. We are currently underinformed on which rehabilitation method will improve CVR, and how this information can inform on a patient’s prognosis and diagnosis. Implementation of targeted rehabilitation regimes would be the first step to elucidate whether such regimes can modulate CVR and in the process may assist in improving our understanding for the underlying vascular pathophysiology. As such, the high spatial resolution along with whole brain coverage offered by MRI has opened the door to exciting recent developments in CVR MRI. Yet, several challenges currently preclude its potential as an effective diagnostic and prognostic tool in treatment planning and guidance. Understanding these knowledge gaps will ultimately facilitate a deeper understanding for cerebrovascular physiology and its role in brain function and rehabilitation. Based on the lessons learned from our group’s past and ongoing neurorehabilitation studies, we present a systematic review of physiological mechanisms that lead to impaired CVR in aging and disease, and how CVR imaging and its further development in the context of brain rehabilitation can add value to the clinical settings.