In vivo time-gated diffuse correlation spectroscopy at quasi-null source-detector separation

Area of Science:

• Biomedical Optics
• Medical Instrumentation
• Physiological Monitoring

Background:

• Diffuse correlation spectroscopy (DCS) is crucial for non-invasively assessing tissue blood flow.
• Traditional DCS systems often require complex time-tagging electronics and can be limited by probe size and photon collection efficiency.

Purpose of the Study:

• To demonstrate a simplified time-domain diffuse correlation spectroscopy (TD-DCS) approach.
• To enable quasi-null source-detector separation measurements for enhanced blood flow detection.
• To reduce instrumentation complexity and probe dimensions for practical applications.

Main Methods:

• Utilized a fast time-gated single-photon avalanche diode (SPAD) detector.
• Implemented TD-DCS at quasi-null source-detector separation.
• Eliminated the need for conventional time-tagging electronics.

Main Results:

• Achieved increased photon collection efficiency.
• Demonstrated simplified real-time instrumentation and reduced probe dimensions.
• Successfully performed depth-discriminating, quasi-null distance blood flow measurements in a human subject.

Conclusions:

• The developed TD-DCS method offers a more practical and efficient approach for blood flow monitoring.
• This technique paves the way for miniaturized optical sensors with improved spatial resolution.
• Enhanced contrast of local blood flow changes can be achieved for advanced physiological monitoring.