Effect of a thin superficial layer on the estimate of hemodynamic changes in a two-layer medium by time domain NIRS

Abstract

Abstract:In order to study hemodynamic changes involved in muscular metabolism by means of time domain fNIRS, we need to discriminate in the measured signal contributions coming from different depths. Muscles are, in fact, typically located under other tissues, e.g. skin and fat. In this paper, we study the possibility to exploit a previously proposed method for analyzing time-resolved fNIRS measurements in a two-layer structure with a thin superficial layer. This method is based on the calculation of the timedependent mean partial pathlengths. We validated it by simulating venous and arterial arm cuff occlusions and then applied it on in vivo measurements. ©2016 Optical Society of America

Probe-hosted silicon photomultipliers for time-domain functional near-infrared spectroscopy: phantom andin vivotests

“…24 To remove the contribution of the more superficial layers, i.e., lipid in the muscle and skull in the head, we applied a correction method based on the refined computation of the path lengths traveled by photons in a two-layer medium. 25,26 The a-priori knowledge of the thickness of the UP layer is necessary and it was measured or estimated for each subject.…”

Time-Domain Near-Infrared Spectroscopy and Imaging: A Review

“…Zucchelli et al and Re et al utilized the analytical formulations of the partial pathlength of Equation (24) with the analytical solutions of the TD-DE for two-layered media to estimate perturbations of µ a2 [32] (pp. [109][110][111][112][113][114][115][116][117][118][119][120][121][122][123][124][125] [152,153]. When the spectroscopic TR reflectance, R(t, λ), is divided into many time gates, the ratio of the perturbed and unperturbed R(t, λ) averaged over the g-th time-gate is derived from Equation (24) as,…”

NIRS-EMG for Clinical Applications: A Systematic Review

“…Photons which arrive later ("late photons") travelled through longer paths inside the tissue and, thus, they investigated deeper layers where the muscular tissue is located. By exploiting these peculiar characteristic of time-resolved measurements, it is possible to remove the more superficial physiological and confounding contributions from the detected signal [61,62]. Up to now, due to the high cost of components and the complexity of the technique, there are few commercially available instruments which exploit the TD-NIRS approach for muscle monitoring.…”