Reproducibility of a time-resolved NIRS, multidistance diffuse correlation spectroscopy system: towards noninvasive...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Imaging

Background:

• Longitudinal monitoring of cerebral blood flow (CBF), oxygenation (StO2), and cerebral metabolic rate of oxygen (CMRO2) is crucial for early detection of secondary brain injury.
• Current monitoring methods may lack the sensitivity or feasibility for frequent, reliable measurements.

Purpose of the Study:

• To assess the reproducibility and reliability of an in-house time-resolved near-infrared spectroscopy (trNIRS) and multidistance diffuse correlation spectroscopy (mdDCS) system for daily monitoring.
• To demonstrate the system's capability for longitudinal monitoring through carotid compression tests.

Main Methods:

• Daily trNIRS/mdDCS measurements were conducted on volunteers over one week.
• Reproducibility was assessed using coefficient of variation (CV), and reliability using intraclass correlation coefficient (ICC).
• Carotid compression was applied to induce controlled changes in CBF, StO2, and CMRO2 for longitudinal assessment.

Main Results:

• Optical measurements demonstrated good-to-excellent within-acquisition, between-acquisition, and between-day reproducibility (CV < 19%) and reliability (ICC 0.67-0.99).
• Short-distance DCS showed sensitivity to probe repositioning.
• Carotid compression reliably reduced CBF, StO2, and CMRO2, with consistent results observed up to three weeks prior.

Conclusions:

• The hybrid trNIRS/mdDCS system is feasible for daily monitoring of cerebral physiological parameters.
• The system offers reliable and reproducible measurements, supporting its use in clinical settings for early detection of neurological changes.