BACKGROUND AND OBJECTIVE: Monitoring dynamic changes during laser induced photothermolysis of vascular skin lesions is essential for obtaining an optimal therapeutic result. Rapid photoinduced thermal damage occurs at a threshold temperature of about 70 degrees C. It is therefore, relevant to identify markers to indicate if this threshold temperature has been reached. Methemoglobin, which is formed by a photo-induced oxidation of hemoglobin, indicates that the temperature has reached this threshold value. This study presents a proof of concept of a method for monitoring the in vivo presence of methemoglobin immediately after laser exposure. STUDY DESIGN/ MATERIALS AND METHODS: The present study was designed to investigate the in vivo temperature dependence of hemoglobin absorption in the 450-800 nm spectrum range. In vivo diffuse reflectance measurements of port-wine stain (PWS) and telangiectasia were performed prior to, and immediately after, laser treatment with a pulsed dye laser (PDL) at 585 nm wavelength. RESULTS: In vivo measurements following laser treatment of vascular skin lesions showed an immediate increase in the optical absorption of blood. This effect, caused by thermal stress, is a result of an increased dermal blood volume fraction and methemoglobin formation. The effect is light dose dependent, and reflectance spectra revealed methemoglobin formation in patients treated with fluences above 5 J/cm2 at 585 nm wavelength. CONCLUSIONS: It was proved that methemoglobin can be measured in vivo by reflectance spectroscopy. Measurements of the average methemoglobin concentrations immediately after laser exposure may be a valuable diagnostic tool to verify that the blood temperature has been sufficiently high to induce thermal damage to the vessel wall. Copyright 2004 Wiley-Liss, Inc.
BACKGROUND AND OBJECTIVE: Monitoring dynamic changes during laser induced photothermolysis of vascular skin lesions is essential for obtaining an optimal therapeutic result. Rapid photoinduced thermal damage occurs at a threshold temperature of about 70 degrees C. It is therefore, relevant to identify markers to indicate if this threshold temperature has been reached. Methemoglobin, which is formed by a photo-induced oxidation of hemoglobin, indicates that the temperature has reached this threshold value. This study presents a proof of concept of a method for monitoring the in vivo presence of methemoglobin immediately after laser exposure. STUDY DESIGN/ MATERIALS AND METHODS: The present study was designed to investigate the in vivo temperature dependence of hemoglobin absorption in the 450-800 nm spectrum range. In vivo diffuse reflectance measurements of port-wine stain (PWS) and telangiectasia were performed prior to, and immediately after, laser treatment with a pulsed dye laser (PDL) at 585 nm wavelength. RESULTS: In vivo measurements following laser treatment of vascular skin lesions showed an immediate increase in the optical absorption of blood. This effect, caused by thermal stress, is a result of an increased dermal blood volume fraction and methemoglobin formation. The effect is light dose dependent, and reflectance spectra revealed methemoglobin formation in patients treated with fluences above 5 J/cm2 at 585 nm wavelength. CONCLUSIONS: It was proved that methemoglobin can be measured in vivo by reflectance spectroscopy. Measurements of the average methemoglobin concentrations immediately after laser exposure may be a valuable diagnostic tool to verify that the blood temperature has been sufficiently high to induce thermal damage to the vessel wall. Copyright 2004 Wiley-Liss, Inc.
Authors: Adrián Alegre-Sánchez; D Saceda-Corralo; G Segurado-Miravalles; D de Perosanz-Lobo; P Fonda-Pascual; O M Moreno-Arrones; D Buendía-Castaño; B Perez-García; P Boixeda Journal: Lasers Med Sci Date: 2017-01-11 Impact factor: 3.161
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Authors: Ekaterina Y Lukianova-Hleb; Alexander O Oginsky; John S Olson; Dmitri O Lapotko Journal: Lasers Surg Med Date: 2011-02-02 Impact factor: 4.025
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