# Noninvasive optical monitoring of tissue with Frequency Domain Diffuse Correlation Spectroscopy

> **NIH NIH R21** · UNIVERSITY OF SOUTH FLORIDA · 2021 · $173,750

## Abstract

PROJECT SUMMARY/ABSTRACT
 Blood flow and blood oxygenation are both important physiological markers of tissue health and function that
can be quantitatively measured using two independent but complementary diffuse optical technologies. Diffuse
Correlation Spectroscopy (DCS) measures the fluctuations in intensity of coherently scattered light to estimate
blood flow, and multi-distance Diffuse Optical Spectroscopy (DOS) estimates blood oxygenation from the
absorption of light by tissue. While the two optical techniques can be combined into a single hybrid fiber optic
probe, differences in the respective volume of tissue interrogated by DCS/DOS could result in systemic errors in
estimation of optical properties – especially when using multi-distance measurements in heterogeneous tissues.
As a result, the accuracy and reliability of hemodynamic responses due to focal changes in tissue function, such
as due to functional activation or due to localized tumors, are poor. This research proposal addresses these
issues, and develops a new diffuse optical technique, Frequency Domain Diffuse Correlation Spectroscopy (FD-
DCS), to simultaneously measure blood flow and blood oxygenation from a single set of measurements without
confounding partial volume effects. More specifically, we develop a generalized tissue light propagation model
that fully describes the diffusion of temporal light fluctuations through tissue, and related instrumentation to
leverage this approach, to estimate static (tissue absorption and reduced scattering coefficients) and dynamic
(tissue blood flow) properties. We characterize coherence, modulation and noise characteristics of the FD-DCS
technique using experiments in tissue simulating phantoms. In addition, we validate the new technique against
existing technologies (and theoretical expectations) via controlled measurements of absorption/scattering
coefficients, and flow in tissue simulating phantoms. Finally, we perform preliminary in vivo feasibility
experiments, to demonstrate and validate the instrument in a biological setting.

## Key facts

- **NIH application ID:** 10141274
- **Project number:** 5R21GM137209-02
- **Recipient organization:** UNIVERSITY OF SOUTH FLORIDA
- **Principal Investigator:** Ashwin Bharadwaj Parthasarathy
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $173,750
- **Award type:** 5
- **Project period:** 2020-05-01 → 2023-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10141274

## Citation

> US National Institutes of Health, RePORTER application 10141274, Noninvasive optical monitoring of tissue with Frequency Domain Diffuse Correlation Spectroscopy (5R21GM137209-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10141274. Licensed CC0.

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