High-speed 2D imaging with frequency-domain near-infrared spectroscopy

2021 ◽  
Author(s):  
Roy A. Stillwell ◽  
Thomas D. O'Sullivan
Keyword(s):  
Infrared Spectroscopy ◽  
Frequency Domain ◽  
Near Infrared Spectroscopy ◽  
High Speed ◽  
Near Infrared ◽  
2D Imaging

scholarly journals A scalable, multi-wavelength, broad bandwidth frequency-domain near-infrared spectroscopy platform for real-time quantitative tissue optical imaging

2021 ◽  
Author(s):  
Roy A. Stillwell ◽  
Vincent J. Kitsmiller ◽  
Alicia Y. Wei ◽  
Alyssa Chong ◽  
Lyla Senn ◽  
...  
Keyword(s):  
Optical Properties ◽  
Infrared Spectroscopy ◽  
Frequency Domain ◽  
Real Time ◽  
Near Infrared Spectroscopy ◽  
High Speed ◽  
Near Infrared ◽  
Single Channel ◽  
Lookup Table ◽  
K Nearest Neighbor

Frequency-domain near-infrared spectroscopy (FD-NIRS) provides quantitative noninvasive measurements of tissue optical absorption and scattering, and provides a safe and accurate method for characterizing tissue composition and metabolism. However, the poor scalability and high complexity of most FD-NIRS systems assembled to date have contributed to its limited clinical impact. To address these shortcomings, we present a scalable, digital-based FD-NIRS platform capable of measuring optical properties and tissue chromophore concentrations in real-time. The system provides single-channel FD-NIRS amplitude/phase, optical property, and chromophore data at a maximum display rate of 36.6 kHz, 17.9 kHz, and 10.2 kHz, respectively, and can be scaled to multiple channels as well as integrated into a handheld format. The entire system is enabled by several innovations including an ultra-high-speed k-nearest neighbor lookup table method (maximum of 250,000 inversions/s for large 2500x700 table of absorption and reduced scattering coefficients), embedded FPGA and CPU high-speed co-processing, and high-speed data transfer (due to on-board processing). We show that our 6-wavelength, broad modulation bandwidth (1-400 MHz) system can be used to perform 2D high-density spatial mapping of optical properties.

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