<title>Near-infrared time-resolved spectroscopy system for tissue oxygenation monitor</title>

Abstract

We developed a three wavelength time-resolved spectroscopy system cadled the TRS-1 0 for use as a tissue oxygenation monitor. The TRS-1 0 achieved a higher data acquisition rate and a system miniaturization maintaining high sensitivity and time resolution. The TRS-1O consists of a three wavelength picosecond light pulser (PLP) with auto power control as a pulsed light source, a photomultiplier tube (PMT) having high speed and high sensitivity and miniaturized signal processing circuits for time-resolved measurement (CFD, TAC, A/D converter and histogram memory). The TRS-1O system was used to measure the time course of oxygen metabolism in a human forearm with a pneumatic cuff attached to occlude blood flow. Our system succeeded in accurately measuring concentrations of Oxy-(Hb02) and deoxyhemoglobin (Hb) in the human forearm based on diffusion theory by means of TRS data observation having an accumulation time of one second per point.

Influence of red laser irradiation on hemoglobin oxygen saturation and blood volume in human skin in vivo

“…These temporal changes of oxygenation disguise small effects of laser induced changes at low light fluence rate (see bellow). The value of blood oxygen saturation in skin at rest (50-70%) at normal ambient temperature (2O-22 C) agrees fairly well with that ofreported by others [4][5][6]. It should be noted that the measurements done at lower ambient temperatures gave the values of blood oxygen saturation in skin at rest as low as 10-30 % with increasing temporal oscillation range.…”

Reduction of V̇O2slow component by priming exercise: novel mechanistic insights from time-resolved near-infrared spectroscopy

“…The principles of operation and algorithms utilized by the equipment have been described in detail elsewhere (Oda et al. ; Ohmae et al. ).…”

“…In the present study, estimation of the optical path length, reduced scattering coefficient ( μ s ’) and absorption coefficient ( μ a ) are achieved by fitting the receiver profile of photon counts over time to a function based on diffusion theory (Oda et al. ; Ohmae et al. ).…”

Slowed oxygen uptake kinetics in hypoxia correlate with the transient peak and reduced spatial distribution of absolute skeletal muscle deoxygenation

“…Each TRS‐20 probe provided picosecond light pulses at three different wavelengths (760, 795 and 830 nm) to measure absolute muscle deoxygenation ([deoxy(Hb + Mb)]; [HHb]), oxygenation ([oxy(Hb + Mb)]; [HbO 2 ]) and total haemoglobin concentration ([Hb + Mb]; [Hb tot ]). Temporal light intensity profiles at each measurement point were fitted with a photon diffusion equation (Oda et al 1999) for estimation of mean optical path length, scattering and absorption coefficients, which allowed quantification of NIRS chromophores in micromoles (Chin et al 2011; Koga et al 2011, 2012). To account for adipose tissue thickness (ATT) on the NIRS signal (Niwayama et al 2000; Koga et al 2011), a novel correction factor based on the relationship between [Hb tot ] and ATT was determined from participants in the rested, upright‐seated position.…”