Abstract
The aim of this study was to evaluate enhancing of the depth sensitivity of time-resolved near-infrared spectroscopy with a subtraction-based approach. Due to the complexity of light propagation in a heterogeneous media, and to prove the validity of the proposed method in a heterogeneous turbid media we conducted a broad analysis taking into account a number of parameters related to the method as well as various parameters of this media. The results of these experiments confirm that the depth sensitivity of the subtraction-based approach is better than classical approaches using continuous-wave or time-resolved methods. Furthermore, the results showed that the subtraction-based approach has a unique, selective sensitivity to a layer at a specific depth. In vivo application of the proposed method resulted in a greater magnitude of the hemodynamic changes during functional activation than with the standard approach.
Highlights
IntroductionAccurate estimation of optical properties of heterogeneous tissue structures by near-infrared spectroscopy (NIRS) methods is challenging [1]
Accurate estimation of optical properties of heterogeneous tissue structures by near-infrared spectroscopy (NIRS) methods is challenging [1]. Perhaps nowhere is this better exemplified than using NIRS to measure the optical properties of brain tissue, which requires contending with significant signal contamination from superficial tissue layers
CW-NIRS is frequently used in functional NIRS studies [4,5]
Summary
Accurate estimation of optical properties of heterogeneous tissue structures by near-infrared spectroscopy (NIRS) methods is challenging [1]. Perhaps nowhere is this better exemplified than using NIRS to measure the optical properties of brain tissue, which requires contending with significant signal contamination from superficial tissue layers (skull and scalp). The most popular and widely used in brain applications is multi-distance continuous-wave (CW) NIRS [2]. This method is based on the assumption that depth sensitivity is proportional to source-detector (rSD) separation. CW-NIRS is frequently used in functional NIRS (fNIRS) studies [4,5]
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