Noninvasive assessment of skin structure by combined photothermal radiometry and optical spectroscopy: coregistration with multiphoton microscopy

Verdel, Nina; Lentsch, Griffin; Balu, Mihaela; Tromberg, Bruce J.; Majaron, Boris

doi:10.1364/ao.57.00d117

Cited by 18 publications

(32 citation statements)

References 23 publications

(47 reference statements)

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“…From the reconstructed temperature profiles, the epidermal-dermal boundary depths (z ed ) were estimated by fitting three log-normal curves to each reconstructed profile and assessing the intersection point between the first and second log-normal curve (see Appendix). Thus, the estimated average epidermis-dermis boundary depth for all volunteers was 0.11 ± 0.02 mm, which is within the reported interval of human epidermis thickness [35,36]. The obtained z ed served as an input parameter for estimation of the epidermal fraction of deposited energy, f epi , calculated as the integral of the epidermal peak divided by the integral over the entire temperature profile.…”

Section: Resultssupporting

confidence: 69%

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

et al. 2019

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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.

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Section: Resultssupporting

confidence: 69%

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

et al. 2019

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“…The applied light is absorbed well by both epidermal melanin and hemoglobin in dermal vasculature. The radiant exposure was estimated to ∼0.30 J/cm at the effective spot size of ~5 mm [1][2][3].…”

Section: Methodsmentioning

confidence: 99%

“…Mid-IR emission from the tissue surface was recorded with a fast IR camera (SC7500 by FLIR Systems Inc.; λ = 3.5-5.1 µm) at a rate of 1000 frames per second. PPTR signals were obtained by lateral averaging of the radiometric data over a suitable area of interest (typically 1 x 1 mm 2 ) and subtracting the baseline value [1][2][3]. The manufacturer provided calibration system (Hypercal TM ) was used for conversion of raw signal amplitudes to radiometric temperature values.…”

Section: Methodsmentioning

confidence: 99%

“…The experimental data are fitted with predictions of a dedicated numerical model of light transport in strongly scattering medium (Monte Carlo) using a four-layer model of skin. This approach allows assessment of the epidermal and dermal thickness, chromophore contents (e.g., melanin, oxy-and deoxy-hemoglobin), as well as scattering properties of both skin and subcutis [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

“…We have recently performed an objective, albeit only partial test of the described approach, based on a comparison of the assessed epidermal thicknesses with the evidence obtained using multi-photon microscopy, which provides optical sectioning capability [2]. In the following, we report on a complementary test of the same technique, in which we compare the results from intact skin in a healthy volunteer with those obtained after application of a bloodpressure cuff at different pressures at the same test site.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Monitoring of Hemodynamics in Human Skin Using Pulsed Photothermal Radiometry and Optical Spectroscopy

Verdel¹,

Majaron²

2018

Proceedings of the 2018 International Conference on Quantitative InfraRed Thermography

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We present a test of our novel methodology for noninvasive quantitative characterization of human skin in vivo involving a customary pressure-cuff test in healthy volunteers at different cuff pressures. Our experimental approach combines time-resolved measurements of mid-infrared emission from sample surface after exposure to a short light pulse and diffuse reflectance spectroscopy in visible part of the spectrum. Both data sets are fitted simultaneously with predictions of a dedicated numerical model of light transport in a four-layer skin model (i.e., inverse Monte Carlo). This approach allows assessment of, e.g., blood contents and oxygenation levels in papillary and reticular dermis.

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Objective monitoring of laser tattoo removal in human volunteers using an innovative optical technique: A proof of principle

Golmajer Zima,

Verdel,

Lukač

et al. 2023

Lasers Surg Med

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ObjectivesAssess the suitability of the technique for objective monitoring of laser tattoo removal by an extended treatment protocol.Materials and MethodsOne half of the tattoo in the first volunteer was treated with nanosecond and the other half with picosecond laser pulses at 1064 nm. In the second subject, four test areas were treated repeatedly using different radiant exposures from 1.5 to 6 J/cm2. Measurements of diffuse reflectance spectra and photothermal radiometric transients were performed 4–20 weeks after each treatment session. Inverse Monte Carlo analysis based on a three‐layer model of tattooed skin was applied to assess the tattoo characteristics and analyze their changes.ResultsThe results clearly indicate a gradual reduction of the ink content and an increase of the subsurface depth of the tattoo layer with all treatments at a radiant exposure of 3 J/cm2 or higher. The observed dependences on laser pulse duration, radiant exposure, and a number of treatments are in excellent agreement with visual fading of the tattoo.ConclusionsThe presented methodology enables noninvasive characterization of tattoos in human skin and objective monitoring of the laser removal treatment.

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Noninvasive assessment of skin structure by combined photothermal radiometry and optical spectroscopy: coregistration with multiphoton microscopy

Cited by 18 publications

References 23 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

Monitoring of Hemodynamics in Human Skin Using Pulsed Photothermal Radiometry and Optical Spectroscopy

Objective monitoring of laser tattoo removal in human volunteers using an innovative optical technique: A proof of principle

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