Characterization of a fiber-coupled SPAD camera system for deep-tissue blood-flow measurement using diffuse...

Area of Science:

• Biomedical Optics
• Medical Imaging
• Photonics

Background:

• Diffuse Correlation Spectroscopy (DCS) is vital for noninvasive blood flow monitoring, particularly cerebral blood flow.
• Conventional DCS faces signal-to-noise ratio (SNR) limitations in deep tissues due to scarce photons and detector scalability issues.

Purpose of the Study:

• To demonstrate a novel DCS system utilizing a 500x500 single-photon avalanche diode (SPAD) array (SwissSPAD3) for enhanced SNR.
• To validate the performance of the SPAD-based DCS system against conventional methods in phantoms and human subjects.

Main Methods:

• Integration of the SwissSPAD3 SPAD array with a custom field-programmable gate array (FPGA) for parallel data acquisition.
• Validation using two-layer liquid phantoms and human measurements, comparing against a lab-standard continuous-wave DCS system.
• Assessment of blood flow tracking at extended source-detector separations up to 3.25 cm.

Main Results:

• The SPAD-based DCS system achieved significant SNR increases compared to conventional DCS.
• Robust blood flow tracking was demonstrated even at large source-detector separations (up to 3.25 cm).
• The system proved effective in both phantom studies and human measurements.

Conclusions:

• SPAD-based parallel detection offers a scalable approach to enhance deep-tissue DCS performance.
• This technology holds promise for improved noninvasive monitoring of blood flow in clinical applications.
• The developed system overcomes limitations of conventional DCS, enabling better signal detection in challenging scenarios.