Vidisha Goyal
BME PhD Proposal Presentation

Date: 2025-03-13
Time: 11:00 AM-1:00 PM
Location / Meeting Link: N357 (HSRB II) / https://emory.zoom.us/j/92555727262

Committee Members:
Erin M. Buckley, PhD (Advisor) Candace C. Fleischer, PhD Francisco Robles, PhD John Oshinski, PhD Ofer Sadan, MD/PhD


Title: Broadband Optical Spectroscopies for measurement of cerebral water content in adults

Abstract:
Cerebral edema refers to an increase in brain water content that leads to an expansion in brain volume. Edema is a common complication following numerous pathologies, including traumatic brain injury and stroke, that is a significant contributor to morbidity and mortality. As edema progresses, it can distort vital brain structures, alter function, and increase intracranial pressure, resulting in secondary brain damage beyond that of the initial injury. Unfortunately, current clinical evaluation of cerebral edema relies on indirect and intermittent assessment via qualitative imaging studies (typically computed tomography) or invasive intraparenchymal or ventricular pressure sensors. There is an urgent need for a non-invasive bedside monitor of brain water content to improve the diagnosis of edema and to assess the efficacy of treatments aimed at reducing edema. Broadband Absorption spectroscopy (BAS) may provide such a monitoring tool. BAS is a non-invasive optical approach that quantifies water concentration at depths of ~1-2cm using the spectral signature of multiply-scattered near-infrared light (650-1000 nm) that is detected at the tissue surface. Previous ex vivo work has validated BAS in tissue-mimicking phantoms, and in vivo work has demonstrated the promise of BAS-measured water estimates in cancerous breast tissue. However, BAS has yet to be used to study brain water content in humans, in part because of the paucity of gold-standard techniques that accurately quantify tissue water content for corroboration, as well as because of the potentially appreciable extracerebral (scalp and skull) influence inherent to the BAS signal due to its non-invasive nature. In pilot work, we have taken the first steps to use BAS to measure regional cerebral water content in adults. We have shown that the technique is feasible in the intensive care unit, and we have used initial studies to refine data collection procedures to optimize data quality. We have shown BAS estimates of brain water are highly repeatable. In a validation study (18 healthy and 6 stroke), we demonstrated strong correlation between BAS-measured water content and quantitative MRI-measured water content within a region of interest encompassing the approximate frontal volume interrogated by BAS, suggesting that the contribution of scalp and skull to the BAS signal may be of small concern to the acute changes that drive or describe therapeutic effect of cerebral edema. Further, we showed BAS is sensitive to decreases in brain water content after hyperosmolar therapy aimed at reducing edema (n=8). However, we must increase our samples sizes and demonstrate that these exciting results are generalizable to a variety of edema etiologies. Thus, our approach will validate BAS and demonstrate its ability to detect changes with edema progression and response to treatment across a clinically diverse patient cohort. Successful completion of these aims will provide the foundation first steps towards a bedside tool that could have a powerful impact to address a major deficit in the clinical management of critically-ill patients suffering from cerebral edema.