A Spectroscopic Diffuse Optical Tomography System for the Continuous 3-D Functional Imaging of Tissue—A Phantom Study

Abstract

This article demonstrates a spectroscopic diffuse optical tomography (DOT) system for the noninvasive continuous imaging of tissue. The system was built on an embedded system architecture along with an algorithm that performs entire system control, data acquisition, noise-free lock-in detection, and wireless data transmission to a host computer, equipped with a graphics processing unit (GPU). The GPU system executes a fast 3-D DOT spectroscopic image reconstruction algorithm. The algorithm computes Jacobians and solves four different depth-sensitive inverse problems of image reconstruction. The host computer sends commands to the DOT server system and collects data, and simultaneously performs high-speed 3-D spectroscopic image reconstruction to display images in real-time. We designed a configurable optical fiber patch to collect depth-resolved diffused light exiting the imaging media by placing the patch on the surface. The simulation and experimental results from two setups showed the spectroscopic imaging capability of the system to map the concentration of oxyhemoglobin, deoxyhemoglobin, and water, and to characterize the tumor located deep inside the tissue. The proposed system uses low-cost LEDs, photodiode detectors, embedded system, and algorithms to perform high-speed 3-D functional imaging and can be further miniaturized. Our promising results pave the way for the development of a low-cost hand-held spectroscopic DOT system for the real-time onsite functional imaging of biological tissue.