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

Farina, Andrea; Torricelli, Alessandro; Bargigia, Ilaria; Spinelli, Lorenzo; Cubeddu, Rinaldo; Foschum, Florian; Jäger, Marion; Simon, Emanuel; Fugger, Oliver; Kienle, Alwin; Martelli, Fabrizio; Ninni, Paola Di; Zaccanti, Giovanni; Milej, Daniel; Sawosz, Piotr; Kacprzak, Michał; Liebert, Adam; Pifferi, Antonio

doi:10.1364/boe.6.002609

Cited by 57 publications

(53 citation statements)

References 47 publications

(57 reference statements)

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“…Phantom measurements (source-detector separation = 2 cm, upper layer μ a = ~0.15 cm -1 and μ' s = ~15 cm -1 ) have demonstrated that a homogeneous fit retrieved the lower layer absorption within <15% discrepancy, as long as the thickness of the upper layer is ≤6 mm [43]. Also, comparing a two-layer model with a homogeneous model on the analysis of in vivo measurements on the forehead of 10 subjects, we obtained a good agreement in the estimate of μ a of the lower layer (~10 mm deep) between the homogeneous fit and the two-layer fit [44]. …”

Section: Resultsmentioning

confidence: 67%

In Vivo, Non-Invasive Characterization of Human Bone by Hybrid Broadband (600-1200 nm) Diffuse Optical and Correlation Spectroscopies

et al. 2016

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Non-invasive in vivo diffuse optical characterization of human bone opens a new possibility of diagnosing bone related pathologies. We present an in vivo characterization performed on seventeen healthy subjects at six different superficial bone locations: radius distal, radius proximal, ulna distal, ulna proximal, trochanter and calcaneus. A tailored diffuse optical protocol for high penetration depth combined with the rather superficial nature of considered tissues ensured the effective probing of the bone tissue. Measurements were performed using a broadband system for Time-Resolved Diffuse Optical Spectroscopy (TRS) to assess mean absorption and reduced scattering spectra in the 600–1200 nm range and Diffuse Correlation Spectroscopy (DCS) to monitor microvascular blood flow. Significant variations among tissue constituents were found between different locations; with radius distal rich of collagen, suggesting it as a prominent location for bone related measurements, and calcaneus bone having highest blood flow among the body locations being considered. By using TRS and DCS together, we are able to probe the perfusion and oxygen consumption of the tissue without any contrast agents. Therefore, we predict that these methods will be able to evaluate the impairment of the oxygen metabolism of the bone at the point-of-care.

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Section: Resultsmentioning

confidence: 67%

In Vivo, Non-Invasive Characterization of Human Bone by Hybrid Broadband (600-1200 nm) Diffuse Optical and Correlation Spectroscopies

et al. 2016

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“…It should be noted that a large variability in the baseline optical properties of human head tissues has been reported in the literature. 58 The regularization method employed here includes elements of the two most commonly used regularization methods used for ERPs, MEG, and EEG source analysis. The relative merits of minimum norm and LORETA as tools for conducting source analysis of electrophysiological data have been previously investigated.…”

Section: Discussionmentioning

confidence: 99%

Combining energy and Laplacian regularization to accurately retrieve the depth of brain activity of diffuse optical tomographic data

et al. 2016

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, "Combining energy and Laplacian regularization to accurately retrieve the depth of brain activity of diffuse optical tomographic data," J. Biomed. Opt. Abstract. Diffuse optical tomography (DOT) provides data about brain function using surface recordings. Despite recent advancements, an unbiased method for estimating the depth of absorption changes and for providing an accurate three-dimensional (3-D) reconstruction remains elusive. DOT involves solving an ill-posed inverse problem, requiring additional criteria for finding unique solutions. The most commonly used criterion is energy minimization (energy constraint). However, as measurements are taken from only one side of the medium (the scalp) and sensitivity is greater at shallow depths, the energy constraint leads to solutions that tend to be small and superficial. To correct for this bias, we combine the energy constraint with another criterion, minimization of spatial derivatives (Laplacian constraint, also used in low resolution electromagnetic tomography, LORETA). Used in isolation, the Laplacian constraint leads to solutions that tend to be large and deep. Using simulated, phantom, and actual brain activation data, we show that combining these two criteria results in accurate (error <2 mm) absorption depth estimates, while maintaining a two-point spatial resolution of <24 mm up to a depth of 30 mm. This indicates that accurate 3-D reconstruction of brain activity up to 30 mm from the scalp can be obtained with DOT.

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“…The curve fitting procedure requires calculation of time-resolved data using a computational model of light propagation for given optical properties in an iterative manner, which as a consequence requires a fast and reliable model for a complex heterogeneous system [15,16].…”

Section: Introductionmentioning

confidence: 99%

Time-resolved near infrared light propagation using frequency domain superposition

Wojtkiewicz¹,

Durdurán²,

Dehghani³

2017

Biomed. Opt. Express

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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).

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

Cited by 57 publications

References 47 publications

In Vivo, Non-Invasive Characterization of Human Bone by Hybrid Broadband (600-1200 nm) Diffuse Optical and Correlation Spectroscopies

In Vivo, Non-Invasive Characterization of Human Bone by Hybrid Broadband (600-1200 nm) Diffuse Optical and Correlation Spectroscopies

Combining energy and Laplacian regularization to accurately retrieve the depth of brain activity of diffuse optical tomographic data

Time-resolved near infrared light propagation using frequency domain superposition

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