Rowan Brothers

BME PhD Proposal Presentation

Date: 2023-02-21
Time: 10AM-11:30AM

Location / Meeting Link: HSRB E260 / https://emory.zoom.us/my/robroth.zoom.link 

Committee Members:
Clinton Joiner; Beatrice Gee; Shella Keilholz; Wilbur Lam; Erin Buckley


Title: Non-invasive optical assessments of cerebral metabolic stress in pediatric sickle cell disease

Abstract:
In sickle cell disease (SCD), chronic anemia coupled with inflammation, red blood cell sickling, and endothelial dysfunction leave patients at high risk of stroke. Cerebral blood flow (CBF) is chronically elevated in SCD to compensate for decreases in oxygen delivery caused by severe anemia. Further compensatory elevations in cerebral oxygen extraction fraction (OEF), i.e., the fraction of oxygen that is extracted by the tissue as blood travels from arteries to veins, have also been observed. It is hypothesized these chronic elevations in both CBF and OEF leave patients ill-equipped to respond to acute increases in oxygen metabolic demand, e.g., due to infection, fever, or injury. This chronic state of cerebral metabolic stress leaves patients at high risk for infarction. Indeed, elevated OEF has been associated with increased risk of infarction and routine measurements of OEF and CBF could potentially be used to assess efficacy of anemia therapies and risk for infarct. However, current methods of measuring CBF and OEF are prohibitively expensive for routine monitoring, require sedation in children <6y, and have limited availability. Thus, there is an unmet clinical need for a way to non-invasively, routinely assess cerebral metabolic stress, and the overall goal of this proposal is to demonstrate the utility of two low-cost, non-invasive optical tools, namely diffuse correlation spectroscopy (DCS) and frequency domain near-infrared spectroscopy (FDNIRS), in assessing cerebral metabolic stress in pediatric patients with SCD. Towards this goal, we first validate DCS measurements of cerebral blood flow against perfusion magnetic resonance imaging (MRI) (Aim 1), we investigate the potential influences of sickle hemoglobin on DCS measurements of cerebral blood flow (Aim 2), and we demonstrate that FDNIRS/DCS are sensitive to reductions in cerebral metabolic stress caused by current stroke prevention therapy for SCD (Aim 3).