Biswas Arindam, Parthasarathy Ashwin B
Department of Electrical Engineering, University of South Florida, Tampa, FL 33620, USA.
IEEE Access. 2022;10:129754-129762. doi: 10.1109/access.2022.3228439. Epub 2022 Dec 12.
Diffuse Correlation Spectroscopy (DCS), a noninvasive optical technique, measures deep tissue blood flow using avalanche photon counting modules and data acquisition devices such as FPGAs or correlator boards. Conventional DCS instruments use in-processor counter modules that consume 32 bits/channel which is inefficient for low-photon budget situations prevalent in diffuse optics. Scaling these photon counters for large-scale imaging applications is difficult due to bandwidth and processing time considerations. Here, we introduce a new, lossless compressed sensing approach for fast and efficient detection of photon counts. The compressed DCS method uses an array of binary-coded-decimal counters to record photon counts from 8 channels simultaneously as a single 32-bit number. We validate the compressed DCS approach by comparisons with conventional DCS in experiments on tissue simulating phantoms and in-vivo arm cuff occlusion. Lossless compressed DCS was implemented with 87.5% compression efficiency. In tissue simulating phantoms, it was able to accurately estimate a tissue blood flow index, with no statistically significant difference compared to conventional DCS. Compressed DCS also recorded blood flow in vivo, in human forearm, with signal-to-noise ratio and dynamic range comparable to conventional DCS. Lossless 87.5% efficient compressed sensing counting of photon counts meets and exceeds benchmarks set by conventional DCS systems, offering a low-cost alternative for fast (~100 Hz) deep tissue blood flow measurement with optics.
扩散相关光谱法（DCS）是一种非侵入性光学技术，它使用雪崩光子计数模块以及诸如现场可编程门阵列（FPGA）或相关器板等数据采集设备来测量深部组织血流。传统的DCS仪器使用处理器内计数器模块，每个通道消耗32位，这对于漫射光学中普遍存在的低光子预算情况效率低下。由于带宽和处理时间的考虑，将这些光子计数器扩展用于大规模成像应用很困难。在此，我们引入一种新的无损压缩传感方法，用于快速高效地检测光子计数。压缩DCS方法使用一系列二进制编码十进制计数器，将来自8个通道的光子计数同时记录为一个32位数字。我们通过在组织模拟体模实验和体内手臂袖带阻塞实验中与传统DCS进行比较，验证了压缩DCS方法。无损压缩DCS的压缩效率达到87.5%。在组织模拟体模中，它能够准确估计组织血流指数，与传统DCS相比无统计学显著差异。压缩DCS还记录了人体前臂的体内血流，其信噪比和动态范围与传统DCS相当。光子计数的87.5%高效无损压缩传感计数达到并超过了传统DCS系统设定的基准，为使用光学方法快速（约100Hz）测量深部组织血流提供了一种低成本替代方案。
