In vivo determination of the optical properties of infant brain using frequency-domain near-infrared spectroscopy

Abstract

We investigate the optical properties of the brain in 23 neonates in vivo using a frequency domain near-infrared spectroscopy (NIRS). In this study, a calibration procedure is employed to determine the absorption and reduced scattering coefficients with single source-detector separation. The absorption coefficients of the infant foreheads are lower than the values reported in adults. A large intersubject variation in the reduced scattering coefficients is also demonstrated. Furthermore, physiological parameters are derived from the absorption coefficients at two wavelengths (788 and 832 nm). The mean total hemoglobin concentration (THC) is 39.7+/-9.8 microM and the mean cerebral blood oxygen saturation (StO2) is 58.7+/-11.2%. Our preliminary results show that this bedside frequent domain NIRS could provide quantitative optical measurement of the infant brain.

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

“…[6][7][8][9][10][11][12][13][14] We focused this study on evaluating the method for TD-NIRS data, in comparison with the traditional homogeneous model. Comparing the performance of this approach for different NIRS modalities (CW, FD, and TD), incorporating realistic noise characteristic for each technology, will require further studies beyond the scope of the present manuscript.…”

“…Various continuous-wave (CW), [1][2][3][4][5] frequency-domain (FD), [6][7][8][9][10][11][12][13][14] and time-domain (TD) [15][16][17][18][19] near-infrared spectroscopy (NIRS) approaches offer the ability to determine the absolute absorption and scattering coefficients of biological tissue. The retrieved optical absorption measured at multiple wavelengths allows quantification of different chromophores' concentrations within the tissue.…”

“…For brain imaging, the robust assessment of cerebral blood volume (CBV) and oxygenation, derived from the measure of hemoglobin concentrations in the brain, is essential for reliable cross-sectional and longitudinal studies of health, disease, and disease progression. 8,9,[19][20][21][22] Continuous-wave methods, such as broadband or hyperspectral approaches originally proposed more than 15 years ago, 2 require spatially 1 or spectrally [2][3][4][5] resolved information in order to disentangle the contributions from tissue absorption and scattering. The frequency-domain multidistance (FDMD) approach based on a homogeneous model 6 has been extensively validated with Monte Carlo simulations, 14 phantoms, 6,12 and animal models.…”

“…11,13 It has been successfully applied to the monitoring of brain oxygenation and metabolism in healthy and brain-injured infants. 8,9,20 Time-resolved approaches are generally based on the nonlinear fit of temporal point spread functions (TPSFs). They have been validated with Monte Carlo simulations and phantoms, 15,23,24 and have been applied to monitor developmental cerebral changes in infants.…”

“…21 Most of the in vivo studies mentioned above have relied on a simple head model described as a homogeneous semi-infinite medium. 1,[6][7][8][9][10]16,[19][20][21][22]25,26 This model has shown promising results in piglets and infants, 5,8,9,11,20,22,27 but it is widely recognized that, in the case of the adult head, its oversimplification causes strong contamination of the brain optical properties by those of the extracerebral tissue. For the FDMD approach, Franceschini et al 12 have shown, with simulations and phantom measurements in a slab geometry, that when a superficial layer thicker than ∼1 cm is present, the error on the retrieved absorption of the second layer can exceed 50%.…”