K. Kaspar

UV Transmission Measurements of Small Skin Specimens with Special Quartz Cuvettes

Background: The penetration of different wavelengths of UV radiation through human skin is of major importance, especially for the determination of photoprotective properties of sunscreens and UV-protective clothes. Objective: In this study we present a new method for the measurement of UV transmission through small skin specimens. Methods: The transmission measurements were performed by using a UV spectrophotometer with an integrating sphere operating in the wavelength range of 280–390 nm. For the skin samples, special quartz glass cuvettes were developed which allowed measurements for very thin and small skin specimens. Furthermore, the cuvettes prevented dehydration of the specimens and guaranteed, by using an additional diaphragm, that the transmission data were derived solely from the small skin specimen examined. Specimens measuring 8 × 3 mm2 with a thickness of 0.3 mm (histometric and sonographic control) were taken from the thighs of 10 subjects via shave biopsy. Results: In the UVA range (315–390 nm) we obtained a mean transmission of 4.6% and for the UVB range (280–315 nm) of 0.9%. No significant (p >0.14) difference of UV transmission was found between the individual skin specimens. Conclusion: This new method seems to be well suitable for UV transmission measurements of small skin specimens. As UVA radiation has a much deeper penetration depth and in in vivo situations dermal hemoglobin could have an effect on UV penetration, the present method is better suitable for the investigation of UVB-induced biological adaptation mechanisms and the impact of topical agents on UVB transmission of the epidermis.

High Frequency Ultrasound for High Resolution Skin Imaging

High frequency and broadband ultrasound in the frequency range above 20 MHz is an efficient modality for the non invasive and high resolution imaging of skin structures and skin diseases like skin tumors and inflammatory processes. However, special system designs and signal processing strategies have to be applied to account for the strong and frequency dependent attenuation of high frequency ultrasound in tissue. In this paper the design of an ultrasound imaging system with a minimum spatial resolution of about 9 , utilizing the frequency range from 30 to 150 MHz, is presented. This system enables the high resolution visualization of the uppermost skin layers, which is of great interest in dermatology and cosmetics. To quantify the imaging properties of the system reference measurements were performed by imaging a glass plate and a wire phantom. Furthermore, image processing techniques for the analysis of three dimensional data sets were adapted to investigate the topology of skin structures like skin layers. Results from in vivo measurements on healthy skin and skin tumors are presented. Übersicht Hochfrequenter und breitbandiger Ultraschall im Frequenzbereich oberhalb von 20 MHz stellt eine leistungsfähige Modalität zur nichtinvasiven und hochauflösenden Abbildung von Hautstrukturen und Hauterkrankungen wie Hauttumoren und entzündlichen Prozessen dar. Es müssen jedoch spezielle Systemkonzepte und Signalverarbeitungstechniken angewandt werden, um der starken und frequenzabhängigen Dämpfung des hochfrequenten Ultraschalls im Gewebe Rechnung zu tragen. In dieser Arbeit wird der Entwurf eines Ultraschallabbildungssystems, das den Frequenzbereich von 30 bis 150 MHz nutzt, mit einer kleinsten räumlichen Auflösung von etwa 9 vorgestellt. Dieses System erlaubt die hochauflösende Darstellung der obersten Hautschichten, was von großem Interesse in der Dermatologie und der Kosmetik ist. Zur Quantifizierung der Abbildungseigenschaften des Systems wurden Referenzmessungen durch Abbildung einer Glasplatte und eines Drahtphantoms durchgeführt. Femer wurden Bildverarbeitungstechniken für die Analyse dreidimensionaler Datensätze adaptiert, um die Topologie von Hautstrukturen (Hautschichten, Haarfollikel) zu untersuchen. Es werden Ergebnisse von Messungen in vivo an gesunder Haut und an Hauttumoren vorgestellt. Für die Dokumentation Hochfrequenter Ultraschall / Ultraschallabbildung / Medizin / Dermatologie / Haut / B/D-scan

Change in ultraviolet (UV) transmission following the application of vaseline to non-irradiated and UVB-exposed split skin

Background  Topical preparations such as emollients used in combination with phototherapy can interfere with such treatment. Objectives This study was performed to investigate the impact of vaseline on the ultraviolet (UV) transmission of non‐irradiated split skin and on split skin previously exposed to UVB radiation. Methods Split‐skin specimens were obtained from 20 patients. In each case, one sample was taken from an area of non‐irradiated skin, while the second was taken from an area that had been previously exposed to UVB. The transmission was spectrophotometrically measured with split skin placed in specially designed quartz glass cuvettes before and after the application of two different amounts of vaseline (2·5 and 17·5 mg cm−2). Results Application of vaseline to skin previously exposed to UVB caused significant (P < 0·0001) changes in UV transmission in certain wavelength ranges. In the UVA range, a greater increase in transmission was achieved with 2·5 mg cm−2 vaseline, whereas in the UVB range, a greater increase was achieved with 17·5 mg cm−2 vaseline. The thicker the layer of vaseline applied, the lower was the difference in transmission between non‐irradiated split skin and UVB‐exposed split skin. Conclusions Application of the correct amount of vaseline can enhance transmission in either the UVA or UVB range, and would enable dose reduction during a course of phototherapy.

UV transmission and UV protection factor (UPF) measured on split skin following exposure to UVB radiation — correlation with the minimal erythema dose (MED)

In this study the ultraviolet (UV) transmission of split skin exposed to UVB radiation and of non‐exposed skin was compared in the 280–390 nm wavelength range and quantified. In addition, the correlation between the increase in the minimal erythema dose (MED) associated with a defined exposure to UVB and the ultraviolet protection factor (UPF) calculated from the transmission data was investigated. The study population consisted of 12 patients. Two pieces of split skin of the same thickness (0.3 mm) were taken from the right thigh of each patient. One specimen was removed from an area of non‐exposed healthy skin and the other from an area which had been exposed to UVB radiation for a period of 12 days in which the initial dose of 1/3 MED was raised by 1/3 MED every 4 days. The split skin specimens were stretched over a special frame; subsequently, the UV transmission was determined with a spectrophotometer. The mean values obtained for UV transmission were all significantly below the initial data for non‐exposed split skin. In the UV range of 280–390 nm, the transmission measured in the exposed specimens was 49.1% of the value measured in the non‐exposed split skin (P<0.05). The corresponding values for the UVA range (315–390 nm) and the UVB range (280315 nm) were 50.1% and 29.5%, respectively (P<0.05), based on the initial transmission data obtained from non‐exposed skin. The clinical determination of MED after 12 days of exposure to UVB yielded mean values that were 3.2 times the initial values. Moreover, the mean UPFs calculated from the transmission data measured at the end of the 12‐day exposure period were also about three times the initial values. The present study has thus established a significant correlation between the clinical MED values and the UPFs calculated from the transmission data measured following exposure to UVB.

High-Frequency Ultrasound (50–150 MHz) in Dermatology

In 1979 Alexander and Miller (1979) and Rukinava and Mohar (1979) reported for the first time on A-scan ultrasound of the skin using an unfocused transducer. They were able to detect echoes of the skin surface and of subsurface dermal structures. In the eighties first prototypes at 15–20 MHz have been developed and basic principles of high resolution ultrasound signal interpretation were established. This research was carried out in a few research groups around the world, in particular in England (Payne 1985), France (Querleux et al. 1988), Germany (Breitbart et al. 1983, 1986, Altmeyer 1989), Denmark (Serup 1984a, 1984b, Serup & Staberg 1987) and Japan (Murakami & Miki 1989). In the following years the knowledge on engineering concepts and dermatology applications of high frequency ultrasonic imaging has been developed significantly (Altmeyer et al. 1992).

High Resolution Estimation of Axial and Transversal Bloodflow with a 50 MHZ Pulsed Wave Doppler System for Dermatology

In this paper an approach for the combined estimation of axial and transversal velocity with special emphasis on high resolution is presented. Our proposed approach was tested using simulated data and measurements obtained from a flow phantom. With the estimated flow profile for the axial velocity it was shown that the flow profile inside the vessel with a diameter of 500 μm and with a flow rate of 0.18 μ1/s was parabolic. The proposed method gives adequate results at the center of the vessel, while the low velocities at the border are over estimated. With the combined estimation strategy complex vessel structures with unknown flow directions are taken into consideration. Subject of our future work is the imaging of the microcirculatory system of the skin.

Kombinierte Erfassung von axialem und transversalem Blutfluß mit einem 50MHz-Ultraschall-B-Bild System für die Dermatologie

Zusammenfassung Hochfrequenter, breitbandiger Ultraschall im Bereich von 50 bis 150 MHz ermoglicht die hochauflosende und nichtinvasive Abbildung sowie die sonographische Funktionsdiagnostik der Haut bei dermatologischen Fragestellungen. Neben der morphologischen Abbildung ist die funktionelle Diagnostik von grosem Interesse, insbesondere in Hinblick auf die qualitative und quantitative Detektion von Blutflus im mikrozirkulatorischen System der Haut [2]. Die hier vorliegenden Bedingungen, insbesondere gegeben durch kleine Gefasdurchmesser und kleine Flusgeschwindigkeiten, stellen sehr hohe Anforderungen an den Entwurf eines solchen Abbildungssystems und an geeignete Methoden der Echosignalverarbeitung. In dieser Arbeit wird ein Verfahren vorgestellt, welches unter spezieller Berucksichtigung eines grosen Orts- und Geschwindigkeitsauflosungsvermogens die kombinierte Schatzung der in Bezug auf die Schallausbreitungsrichtung axialen und transversalen Flusgeschwindigkeit und damit die Schatzung der tatsachlichen Geschwindigkeitsverteilung ermoglicht. Die Eigenschaften des Verfahrens werden an Simulationsdaten und Mesdaten eines Flusphantoms demonstriert.

Sonographie der Haut und Subkutis einschließlich der Lymphknoten

Seit Einfuhrung der Ultraschalldiagnostik in die Dermatologie zu Beginn der 90er Jahre hat dieses diagnostische Verfahren eine grose Entwicklung erlebt und wird inzwischen zur Beurteilung oberflachennaher und subkutaner Strukturen sowie zur Beurteilung peripherer Lymphknoten in vielen Kliniken und dermatologischen Praxen eingesetzt.