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Cerebral Blood Flow-Based Resting State Functional Connectivity of the Human Brain using Optical Diffuse Correlation Spectroscopy
Published on: May 27, 2020
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Depth-Sensitive Cerebral Blood Flow and Low-Frequency Oscillations for Consciousness Assessment Using Time-Gated
Medrxiv : the Preprint Server for Health Sciences
|September 15, 2025
Summary
Time-gated diffuse correlation spectroscopy (TG-DCS) shows promise for bedside monitoring of brain states. This noninvasive technique differentiates healthy, covertly conscious, and comatose states by analyzing cerebral blood flow and oscillations.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Medical Physics
Background:
- Assessing brain states in critically ill patients, such as those with traumatic brain injury (TBI), is challenging.
- Current methods for monitoring cerebral blood flow (CBF) and brain activity are often invasive or lack depth sensitivity.
- Distinguishing between different levels of consciousness requires sensitive and accessible monitoring tools.
Purpose of the Study:
- To evaluate the feasibility of depth-sensitive bedside monitoring of CBF and low-frequency oscillations (LFOs) using time-gated diffuse correlation spectroscopy (TG-DCS).
- To differentiate between healthy controls, comatose TBI patients, and covertly conscious individuals in the subacute phase.
- To assess the potential of TG-DCS in detecting residual cortical reactivity.
Main Methods:
- Utilized a 1064 nm TG-DCS system with superconducting nanowire single-photon detectors to collect resting-state data.
- Collected 10-minute data from 25 healthy subjects, one comatose patient, and one covertly conscious subject.
- Analyzed photon arrival times to separate superficial and deep brain signals, extracting blood flow index (BFI) and quantifying LFOs in specific frequency bands.
Main Results:
- Low-frequency oscillation power increased progressively from healthy to covert to comatose states, particularly in late-gated (deep) signals.
- Late-gated BFI was elevated in injured brain states compared to healthy controls.
- Functional responses to an auditory stimulus showed a canonical hemodynamic profile in healthy subjects but delayed reactivity in the covertly conscious individual.
Conclusions:
- TG-DCS is a feasible noninvasive bedside tool for monitoring brain states and distinguishing between different levels of consciousness.
- The technique can detect residual cortical reactivity, offering valuable insights into brain function in injured patients.
- Further validation in larger patient cohorts is warranted to establish its clinical utility.
