High-speed multi-exposure laser speckle contrast imaging with a single-photon counting camera

Area of Science:

• Biomedical Optics
• Neuroimaging
• Medical Imaging Technology

Background:

• Laser speckle contrast imaging (LSCI) is a key technique for assessing cerebral blood flow (CBF).
• Existing LSCI methods face limitations in temporal resolution and accuracy.
• Advancements in sensor technology offer opportunities to improve LSCI performance.

Purpose of the Study:

• To introduce and validate a novel multi-exposure laser speckle imaging (MESI) method.
• To leverage a CMOS single-photon avalanche diode (SPAD) array for enhanced LSCI.
• To achieve real-time CBF measurement with improved temporal resolution and accuracy.

Main Methods:

• Developed a MESI approach using high-frame rate acquisition with minimal inter-frame dead time.
• Utilized a CMOS SPAD array for noise-free readout and high sensitivity.
• Conducted in vivo comparative measurements on a mouse brain against standard LSCI.

Main Results:

• The MESI method successfully mimicked multiple exposures in a single-shot acquisition series.
• Real-time speckle contrast measurements were achieved with high temporal resolution.
• Comparative in vivo studies demonstrated the feasibility and performance of the new approach.

Conclusions:

• The presented MESI method, utilizing a SPAD array, provides a significant advancement for CBF imaging.
• This technique enables accurate and high-temporal-resolution assessment of cerebral blood flow.
• The findings support the potential of MESI for real-time neuroimaging applications.