Experimental study of NIR transmittance of the human skull

Лычагов, В. В.; Tuchin, Valery V.; Vilensky, Maxim A.; Reznik, Boris; Ichim, Thomas E.; Taboada, Luis De

doi:10.1117/12.650116

Cited by 17 publications

(7 citation statements)

References 5 publications

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“…If there is incremental attenuation of NILT penetration due to the additional barriers, even by 50–90%, then the delivered power density on the cortical surface would be estimated to be 2.9–14.5 mW/cm 2 . This would be in agreement with the abstracted conference proceedings study of Lychagov [ 32 ].…”

Section: Discussionsupporting

confidence: 91%

“…Secondly, and most important, there is no evidence demonstrating that the treatment was adequately optimized prior to NEST trial initiation. While there is brief abstract report in the scientific meeting literature [ 32 ] discussing NILT, there is limited peer-reviewed literature documenting optimized parameters for NILT across the skull into the brain tissue that can be used as a guide for clinical trial design. For example, the original NEST-1 trial article by Lampl and colleagues specified a cortex surface fluence of 1 J/cm 2 [ 15 ], the NEST-2 trial paper by Zivin et al does not specify any power density treatment regimen [ 16 ], and the NEST-3 trial article is also devoid of important information regarding the treatment regimen used in the study [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

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Transcranial Near-Infrared Laser Transmission (NILT) Profiles (800 nm): Systematic Comparison in Four Common Research Species

et al. 2015

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Background and PurposeTranscranial near-infrared laser therapy (TLT) is a promising and novel method to promote neuroprotection and clinical improvement in both acute and chronic neurodegenerative diseases such as acute ischemic stroke (AIS), traumatic brain injury (TBI), and Alzheimer’s disease (AD) patients based upon efficacy in translational animal models. However, there is limited information in the peer-reviewed literature pertaining to transcranial near-infrared laser transmission (NILT) profiles in various species. Thus, in the present study we systematically evaluated NILT characteristics through the skull of 4 different species: mouse, rat, rabbit and human.ResultsUsing dehydrated skulls from 3 animal species, using a wavelength of 800nm and a surface power density of 700 mW/cm2, NILT decreased from 40.10% (mouse) to 21.24% (rat) to 11.36% (rabbit) as skull thickness measured at bregma increased from 0.44 mm in mouse to 0.83 mm in rat and then 2.11 mm in rabbit. NILT also significantly increased (p<0.05) when animal skulls were hydrated (i.e. compared to dehydrated); but there was no measurable change in thickness due to hydration.In human calvaria, where mean thickness ranged from 7.19 mm at bregma to 5.91 mm in the parietal skull, only 4.18% and 4.24% of applied near-infrared light was transmitted through the skull. There was a slight (9.2-13.4%), but insignificant effect of hydration state on NILT transmission of human skulls, but there was a significant positive correlation between NILT and thickness at bregma and parietal skull, in both hydrated and dehydrated states.ConclusionThis is the first systematic study to demonstrate differential NILT through the skulls of 4 different species; with an inverse relationship between NILT and skull thickness. With animal skulls, transmission profiles are dependent upon the hydration state of the skull, with significantly greater penetration through hydrated skulls compared to dehydrated skulls. Using human skulls, we demonstrate a significant correlation between thickness and penetration, but there was no correlation with skull density. The results suggest that TLT should be optimized in animals using novel approaches incorporating human skull characteristics, because of significant variance of NILT profiles directly related to skull thickness.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Transcranial Near-Infrared Laser Transmission (NILT) Profiles (800 nm): Systematic Comparison in Four Common Research Species

et al. 2015

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“…Human scalp, skull, and brain tissue have been examined for absorption and scattering properties of light and for NIR light transmission and attenuation in vivo during brain surgery. Transmittance and diffuse reflectance of ex vivo samples of human cadaver skull and skull, scalp and brain have also been measured . Those studies involved transmission, scattering, and temperature measurements on excised non‐preserved human skull and brain tissue as well as formalin preserved tissue.…”

Section: Discussionmentioning

confidence: 99%

Quantitative analysis of transcranial and intraparenchymal light penetration in human cadaver brain tissue

et al. 2015

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Transcranial light measurements of unfixed human cadaver brains allowed for determinations of light penetration variables. While unfixed human cadaver studies do not reflect all the conditions seen in the living condition, comparisons of light scatter and penetration and estimates of fluence levels can be used to establish further clinical dosing. The 808 nm wavelength light demonstrated superior CNS tissue penetration.

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“…This is to be compared to NILT of 11.26% (mean thickness 2.11 mm) in rabbits, 21.24% in rats (mean thickness 0.829 mm) and 40.10% in mice, when measures were done on dehydrate skulls. This data indicates that NILT penetration significantly decreases as skull thickness increases [21,22].…”

Section: Transcranial Nir Laser Transmission Profiles (800 Nm)mentioning

confidence: 70%

Recent Advances in the Laser Radiation Transport through the Head Tissues of Humans and Animals – A Review

Sabeeh

Tuchin

2020

J-BPE

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Modern studies of the penetration of light into biological tissues is becoming very important in various medical applications. This is an important factor for determining the optical dose in many diagnostic and therapeutic procedures. The absorption and scattering properties of the tissue under study determine how deeply the light will penetrate into the tissue. However, these optical properties are highly dependent on the wavelength of the light source and tissue condition. This overview paper analyzes the transmission of light through different areas of human and animal head tissues, and the optimal laser wavelength and power density required to reach different parts of the brain are determined using lasers with different wavelengths by comparing the distribution of fluence, penetration depth and the mechanism of interaction between laser light and head tissues. The power variation in different regions of the head is presented, as estimated using Monte Carlo (MC) simulations. Data are analyzed for the absorption and scattering coefficients of the head tissue layers (scalp, skull, brain), calculated using integrating sphere measurements and inverse problem solving algorithms such as inverse MC (IMC) and adding-doubling (IAD). This study not only offered a quantitative comparison between wavelengths in terms of light transmission efficiency, but also anticipated the exciting opportunity for online, accurate and visible optimization of LLLT lighting parameters.

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Experimental study of NIR transmittance of the human skull

Cited by 17 publications

References 5 publications

Transcranial Near-Infrared Laser Transmission (NILT) Profiles (800 nm): Systematic Comparison in Four Common Research Species

Transcranial Near-Infrared Laser Transmission (NILT) Profiles (800 nm): Systematic Comparison in Four Common Research Species

Quantitative analysis of transcranial and intraparenchymal light penetration in human cadaver brain tissue

Recent Advances in the Laser Radiation Transport through the Head Tissues of Humans and Animals – A Review

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