Comparison of a layered slab and an atlas head model for Monte Carlo fitting of time-domain near-infrared spectroscopy data of the adult head

Abstract:The in-vivo optical properties of the human head are investigated in the 600-1100 nm range on different subjects using continuous wave and time domain diffuse optical spectroscopy. The work was performed in collaboration with different research groups and the different techniques were applied to the same subject. Data analysis was carried out using homogeneous and layered models and final results were also confirmed by Monte Carlo simulations. The depth sensitivity of each technique was investigated and related to the probed region of the cerebral tissue. This work, based on different validated instruments, is a contribution to fill the existing gap between the present knowledge and the actual in-vivo values of the head optical properties.

Section: Discussionmentioning

confidence: 99%

In-vivo multilaboratory investigation of the optical properties of the human head

Farina¹,

Torricelli²,

Bargigia³

et al. 2015

“…The 80% limit cuts off the early photons where the diffusion approximation does not represent the light transport well. The late photons limit is often related to the noise level of measured curve and may vary between 20% -1% [40][41][42][43].…”

Section: Discussionmentioning

confidence: 99%

“…The TPSF region of interest (ROI) is defined as a percentage of the maximum value of a TPSF, which is set to 80% on the leading edge and 5% on the falling edge as shown in Fig. 3 as it has been reported [40][41][42][43] that the 50%-100% leading edge limit and 20% -1% falling edge limit can be used to carry out the procedure of curve fitting. Accuracy of the TPSF calculated in the frequency domain Eq.…”

Section: Accuracy and Speedmentioning

confidence: 99%

Time-resolved near infrared light propagation using frequency domain superposition

Wojtkiewicz¹,

Durdurán²,

Dehghani³

2017

Time-resolved temporal point spread function (TPSF) measurement of near infrared spectroscopic (NIRS) data allows the estimation of absorption and reduced scattering properties of biological tissues. Such analysis requires an iterative calculation of the theoretical TPSF curve using mathematical and computational models of the domain being imaged which are computationally complex and expensive. In this work, an efficient methodology for representing the TPSF data using a superposition of cosines calculated in frequency domain is presented. The proposed method is outlined and tested on finite element realistic models of the human neck and head. Using an adult head model containing ~140k nodes, the TPSF calculation at each node for one source is accelerated from 3.11 s to 1.29 s within an error limit of ± 5% related to the time domain calculation method. 1957-1975 (1995).

“…The Monte Carlo method [39][40][41] can provide a flexible modeling framework to simulate specific experimental or clinical conditions and to assess the contribution of each of the three chromophores to attenuation signals at different wavelengths. There is no doubt that such a comprehensive sensitivity analysis will be instrumental in revealing the physical basis of optical measurements obtained from brain tissues.…”

Section: Discussionmentioning

confidence: 99%

Optimal wavelength combinations for near-infrared spectroscopic monitoring of changes in brain tissue hemoglobin and cytochrome c oxidase concentrations

Arifler

Zhu

Madaan

et al. 2015

Abstract:We analyze broadband near-infrared spectroscopic measurements obtained from newborn piglets subjected to hypoxia-ischemia and we aim to identify optimal wavelength combinations for monitoring cerebral tissue chromophores. We implement an optimization routine based on the genetic algorithm to perform a heuristic search for discrete wavelength combinations that can provide accurate concentration information when benchmarked against the gold standard of 121 wavelengths. The results indicate that it is possible to significantly reduce the number of measurement wavelengths used in conjunction with spectroscopic algorithms and still achieve a high performance in estimating changes in concentrations of oxyhemoglobin, deoxyhemoglobin, and oxidized cytochrome c oxidase. While the use of a 3-wavelength combination leads to mean recovery errors of up to 10%, these errors drop to less than 4% with 4 or 5 wavelengths and to even less than 2% with 8 wavelengths.