Physiological and structural characterization of human skin in vivo using combined photothermal radiometry and diffuse reflectance spectroscopy

Verdel, Nina; Marin, Ana; Milanič, Matija; Majaron, Boris

doi:10.1364/boe.10.000944

Cited by 38 publications

(78 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Roughly at z = 0.4 mm, a transition to a region with markedly lower temperatures starts. This temperature drop agrees well with the reported decrease of the blood volume fraction from the papillary (2–4%) to the reticular dermis (1–2%) . The same transition, albeit not so evident, is present also in the two IR temperature profiles.…”

Section: Resultssupporting

confidence: 91%

Temperature Depth Profiles Induced in Human Skin In Vivo Using Pulsed 975 nm Irradiation

et al. 2019

Self Cite

View full text Add to dashboard Cite

Background and Objectives The aim of this study was to determine the temperature depth profiles induced in human skin in vivo by using a pulsed 975 nm diode laser (with 5 ms pulse duration) and compare them with those induced by the more common 532 nm (KTP) and 1,064 nm (Nd:YAG) lasers. Quantitative assessment of the energy deposition characteristics in human skin at 975 nm should help design of safe and effective treatment protocols when using such lasers. Study Design/Materials and Methods Temperature depth profiles induced in the human skin by the three lasers were determined using pulsed photothermal radiometry (PPTR). This technique involves time‐resolved measurement of mid‐infrared emission from the irradiated test site and reconstruction of the laser‐induced temperature profiles using an earlier developed optimization algorithm. Measurements were performed on volar sides of the forearms in seven volunteers with healthy skin. At irradiation spot diameters of 3–4 mm, the radiant exposures were 0.24, 0.36, and 5.7 J/cm2 for the 975, 532, and 1,064 nm lasers, respectively. Results Upon normalization to the same radiant exposure of 1 J/cm 2, the assessed maximum temperature rise in the epidermis averaged 0.8 °C for the 975 nm laser, 7.4 °C for the 532 nm, and 0.6 °C for the 1,064 nm laser. The characteristic subsurface depth to which 50% of the absorbed laser energy was deposited was on average 0.31 mm at 975 nm irradiation, and slightly deeper at 1,064 nm, and 0.15 mm at 532 nm. The experimentally obtained relations were reproduced in a dedicated numerical simulation. Conclusions The assessed energy deposition characteristics show that the pulsed 975 nm diode laser is very suitable for controlled heating of the upper dermis as required, for example, for nonablative skin rejuvenation. The risks of nonselective overheating of the epidermis and subcutis are significantly reduced in comparison with irradiation at 532 and 1,064 nm, respectively. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

show abstract

Section: Resultssupporting

confidence: 91%

Temperature Depth Profiles Induced in Human Skin In Vivo Using Pulsed 975 nm Irradiation

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…This reduces the ambiguity in the assessed values due to intrinsic correlations between the model parameters, thus enabling robust monitoring of physiological changes in skin upon various stimuli (e.g., obstruction of cutaneous blood circulation and sun exposure). Applying the same approach in direct inverse MC analysis is also possible, but leads to a considerably higher computational load due to increased dimensionality of the resulting optimization problem confounded with the stochastic noise inherent in this numerical technique [46].…”

Section: Resultsmentioning

confidence: 99%

Suitability of diffusion approximation for an inverse analysis of diffuse reflectance spectra from human skin in vivo

et al. 2019

Self Cite

View full text Add to dashboard Cite

Diffusion approximation (DA) of the radiative transport equation allows derivation of enclosed solutions for diffuse reflectance from multi-layer scattering structures, such as human skin. Although the DA is known to be inadequate near tissue boundaries and light sources, analytical tractability makes such solutions very attractive for use in noninvasive characterization of biological organs based on measured diffuse reflectance spectra (DRS). For the presented three-layer model of human skin, which enables a good match with DRS in visible spectral range measured with an integrating sphere, the DA solutions systematically overshoot numerically simulated DRS (using Monte Carlo approach) by 1-2 percentage points. However, using the former in inverse analysis of the latter can result in much larger artifacts, most notably overestimations of the melanin and blood contents by up to 15%, which must be considered when analyzing experimental DRS. Despite such systematic errors, the described approach allows simple and robust monitoring of physiological changes in human skin, as demonstrated in tests involving temporary obstruction of blood circulation and seasonal variations due to extensive sun exposure.

show abstract

“…The ability of the hyperspectral system to sense changes in the wounds is dependent on the ability of these changes to influence the reflectance. The reflectance is determined by the optical properties of the tissue, which is typically modeled as a multilayer structure with absorption and scattering coefficients μ a (λ) and μ s (λ) in each layer [28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Hyperspectral characterization of re‐epithelialization in an in vitro wound model

Bjørgan

Pukstad

Randeberg

2020

Journal of Biophotonics

View full text Add to dashboard Cite

In vitro wound models are useful for research on wound re-epithelialization. Hyperspectral imaging represents a non-destructive alternative to histology analysis for detection of reepithelialization. This study aims to characterize the main optical behavior of a wound model in order to enable development of detection algorithms. K-Means clustering and agglomerative analysis were used to group spatial regions based on the spectral behavior, and an inverse photon transport model was used to explain differences in optical properties. Six samples of the wound model were prepared from human tissue and followed over 22 days. Re-epithelialization occurred at a mean rate of 0.24 mm 2 /day after day 8 to 10. Suppression of wound spectral features was the main feature characterizing re-epithelialized and intact tissue. Modeling the photon transport through a diffuse layer placed on top of wound tissue properties reproduced the spectral behavior. The missing top layer represented by wounds is thus optically detectable using hyperspectral imaging.

show abstract

Physiological and structural characterization of human skin in vivo using combined photothermal radiometry and diffuse reflectance spectroscopy

Cited by 38 publications

References 51 publications

Temperature Depth Profiles Induced in Human Skin In Vivo Using Pulsed 975 nm Irradiation

Temperature Depth Profiles Induced in Human Skin In Vivo Using Pulsed 975 nm Irradiation

Suitability of diffusion approximation for an inverse analysis of diffuse reflectance spectra from human skin in vivo

Hyperspectral characterization of re‐epithelialization in an in vitro wound model

Contact Info

Product

Resources

About