A 15.6 frames per second 1-megapixel multiple exposure laser speckle contrast imaging setup

Area of Science:

• Biomedical Engineering
• Optical Imaging
• Microcirculation Research

Background:

• Laser speckle contrast imaging (LSCI) is a valuable technique for visualizing blood flow.
• Traditional LSCI systems face limitations in processing speed and image quality.
• Multiple exposure time imaging (MELSCI) offers potential for improved perfusion assessment.

Purpose of the Study:

• To develop and validate a high-speed MELSCI system for enhanced blood perfusion visualization.
• To implement a field programmable gate array (FPGA) for real-time processing of MELSCI data.
• To evaluate the system's performance in a human finger occlusion model.

Main Methods:

• A MELSCI setup was engineered with a 1000 fps camera and FPGA for rapid image acquisition and processing.
• Images with multiple exposure times (1-64 ms) were generated via cumulative summation of consecutive snapshots.
• Local contrast was computed using 4x4 pixel regions, with averaging for signal-to-noise improvement.

Main Results:

• The FPGA implementation enabled calculation of contrast images at all exposure times within 28 ms.
• The system achieved processing rates of 15.6 fps for MELSCI data.
• Significant contrast changes were observed during finger occlusion and subsequent hyperemia, validating the system's efficacy.

Conclusions:

• The developed FPGA-based MELSCI system provides high-speed, high-quality blood perfusion imaging.
• This technology enables improved microcirculatory perfusion estimates compared to single exposure time methods.
• The system demonstrates robust performance in dynamic physiological studies, such as occlusion-induced hyperemia.