A comparison between flat and spherical models of the human head for NIR light propagation

2021 ◽  
Author(s):  
Demian A. Vera ◽  
Maria V. Waks Serra ◽  
Hector A. Gracia ◽  
Guido R. Baez ◽  
Daniela I. Iriarte ◽  
...  
Keyword(s):  
Light Propagation ◽  
Human Head ◽  
Nir Light ◽  
Spherical Models

Monte Carlo simulation of light propagation in adult brain: influence of tissue blood content and indocyanine green

2008 ◽  
Vol 16 (2) ◽  
Author(s):  
P. Niederer ◽  
R. Mudra ◽  
E. Keller
Keyword(s):  
Monte Carlo ◽  
Indocyanine Green ◽  
Light Propagation ◽  
Near Infrared ◽  
Human Head ◽  
Adult Brain ◽  
Blood Content ◽  
Representative Model ◽  
Adult Head ◽  
Clinically Significant

AbstractNear-infrared spectroscopy (NIRS), applied to a human head, is a noninvasive method in neurointensive care to monitor cerebral hemodynamics and oxygenation. The method is particularly powerful when it is applied in combination with indocyanine green (ICG) as a tracer substance. In order to assess contributions to the measured optical density (OD) which are due to extracerebral circulation and disturb the clinically significant intracerebral signals, we simulated the light propagation in an anatomically representative model of the adult head derived from MRI measurements with the aid of Monte Carlo methods. Since the measured OD signal depends largely on the relative blood content in various transilluminated tissues, we weighted the calculated densities of the photon distribution under baseline conditions within the tissues with the changes and aberrations of the relative blood volumes which we expect to prevail under physiological conditions. Furthermore, the influence of the IGC dye as a tracer substance was assessed. We conclude that up to about different 70% of the measured OD signal may have its origin in the tissues of interest under optimal conditions, which is mainly due to the extrapolated high relative blood content of brain tissue along with the influence of ICG.

scholarly journals The complete ellipsoidal shell-model in EEG imaging

2006 ◽  
Vol 2006 ◽  
pp. 1-18 ◽  
Author(s):  
S. N. Giapalaki ◽  
F. Kariotou
Keyword(s):  
Cerebrospinal Fluid ◽  
Shell Model ◽  
Electric Dipole ◽  
Human Head ◽  
Observation Point ◽  
Ellipsoidal Shell ◽  
Exterior Space ◽  
Proposed Model ◽  
Spherical Models ◽  
The Brain

This work provides the solution of the direct Electroencephalography (EEG) problem for the complete ellipsoidal shell-model of the human head. The model involves four confocal ellipsoids that represent the successive interfaces between the brain tissue, the cerebrospinal fluid, the skull, and the skin characterized by different conductivities. The electric excitation of the brain is due to an equivalent electric dipole, which is located within the inner ellipsoid. The proposed model is considered to be physically complete, since the effect of the substance surrounding the brain is taken into account. The direct EEG problem consists in finding the electric potential inside each conductive space, as well as at the nonconductive exterior space. The solution of this multitransmission problem is given analytically in terms of elliptic integrals and ellipsoidal harmonics, in such way that makes clear the effect that each shell has on the next one and outside of the head. It is remarkable that the dependence on the observation point is not affected by the presence of the conductive shells. Reduction to simpler ellipsoidal models and to the corresponding spherical models is included.

scholarly journals Monte Carlo modeling of light propagation in the human head for applications in sinus imaging

2015 ◽  
Vol 20 (3) ◽  
pp. 035004 ◽  
Author(s):  
Albert E. Cerussi ◽  
Nikhil Mishra ◽  
Joon You ◽  
Naveen Bhandarkar ◽  
Brian Wong
Keyword(s):  
Monte Carlo ◽  
Light Propagation ◽  
Human Head ◽  
Monte Carlo Modeling

scholarly journals Effect of head model on Monte Carlo modeling of spatial sensitivity distribution for functional near-infrared spectroscopy

2015 ◽  
Vol 08 (05) ◽  
pp. 1550024 ◽  
Author(s):  
Ting Li ◽  
Yan Li ◽  
Yunlong Sun ◽  
Meixue Duan ◽  
Liyuan Peng
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Light Propagation ◽  
Near Infrared ◽  
Human Head ◽  
Head Model ◽  
Functional Near Infrared Spectroscopy ◽  
Quantitative Evidence ◽  
Spatial Sensitivity ◽  
Sensitivity Distribution

Modeling Light propagation within human head to deduce spatial sensitivity distribution (SSD) is important for Near-infrared spectroscopy (NIRS)/imaging (NIRI) and diffuse correlation tomography. Lots of head models have been used on this issue, including layered head model, artificial simplified head model, MRI slices described head model, and visible human head model. Hereinto, visible Chinese human (VCH) head model is considered to be a most faithful presentation of anatomical structure, and has been highlighted to be employed in modeling light propagation. However, it is not practical for all researchers to use VCH head models and actually increasing number of people are using magnet resonance imaging (MRI) head models. Here, all the above head models were simulated and compared, and we focused on the effect of using different head models on predictions of SSD. Our results were in line with the previous reports on the effect of cerebral cortex folding geometry. Moreover, the influence on SSD increases with the fidelity of head models. And surprisingly, the SSD percentages in scalp and gray matter (region of interest) in MRI head model were found to be 80% and 125% higher than in VCH head model. MRI head models induced nonignorable discrepancy in SSD estimation when compared with VCH head model. This study, as we believe, is the first to focus on comparison among full serials of head model on estimating SSD, and provided quantitative evidence for MRI head model users to calibrate their SSD estimation.

Monte Carlo modeling of light propagation in the human head for applications in sinus imaging

2015 ◽  
Author(s):  
Albert E. Cerussi ◽  
Nikhil Mishra ◽  
Joon You ◽  
Naveen Bhandarkar ◽  
Brian J. F. Wong
Keyword(s):  
Monte Carlo ◽  
Light Propagation ◽  
Human Head ◽  
Monte Carlo Modeling
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