Tara Urner BME PhD Proposal Presentation Date:2022-03-25 Time: 1:00 - 2:00PM Location / Meeting Link: https://emory.zoom.us/j/98983030101 Committee Members: Erin Buckley (Advisor) Brandon Dixon Ofer Sadan Francisco Robles Shella Keilholz Title: Noninvasive optical assessment of microvascular blood flow waveforms – a novel biomarker of cerebrovascular health Abstract: The vasculature of the brain must be highly reactive to its physiological environment to ensure adequate delivery of oxygen and nutrients to the most metabolically demanding and delicate organ in the body. Cerebral blood flow, blood volume, and perfusion pressure, are maintained in dynamic equilibrium through coordinated adjustments in vasomotor tone. Pulsatile inflow from the heart is met by both static and dynamic resistance from the complex cerebrovascular tree, such that the resulting cerebral blood flow waveform at the cardiac frequency carries information about vascular compliance, vasomotor tone, and critical closing pressure. Indeed, the value of characterizing pulsatile flow in the brain has been demonstrated by the widespread adoption of transcranial doppler ultrasound (TCD) to clinical management of brain injury. However, TCD is sensitive to the large feeding arteries of the brain, and cannot sense the microvasculature, which is the site of nutrient and oxygen exchange where many pathologies originate. In contrast, diffuse correlation spectroscopy (DCS) is a non-invasive optical modality that measures microvascular blood flow. Recent advances in DCS acquisition speeds (up to 100Hz) now allow resolution of pulsatile microvascular cerebral blood flow. This proposal takes the initial steps of exploring the utility of this pulsatile flow to determine normative values for metrics of waveform morphology (Aim 1) and to quantify how these metrics change with brain injury (Aim 2).