Background: Quantitative measurement of photosensitizer during photodynamic therapy (PDT) is critical. One of the practical approaches is to measure photosensitizer’s fluorescence, however, the influence of tissue optic properties needs to be considered in in situ measurement. Objective: To design and validate a combined system for dual detection of fluorescence and tissue diffuse reflectance. Materials and Method: For fluorescence detection, a 405 nm laser was used for excitation, a power meter for monitoring laser power and a fiber optic spectrometer for recording fluorescence. For diffuse reflectance measurement, a halogen lamp was used as light source and a fiber optic spectrometer for recording diffuse reflectance. Hemoporfin (HMME) was used as a model photosensitizer. Mice were used to evaluate the dual detection function of fluorescence and tissue diffuse reflectance after i.v. injection of HMME. Results: Solutions of different concentrations of HMME were used to test the intensity responses of the fluorescence detection system. A linear correlation was observed at HMME concentration lower than 10 μg/ml. Dual-band correction using corresponding diffuse reflectance data was used for the correction of original fluorescence spectrum. Diffuse reflectance corrected fluorescence data might truly reflect HMME concentration in the skin tissue. Conclusion: The preliminary evaluation suggests that the combined system can be used for quantitative measurement of photosensitizer fluorescence.
Background: Mouse model is a unique tool for preclinical evaluation of photosensitizing drugs for their potential applications in photodynamic therapy (PDT). The fluorescent property of photosensitizer provides a useful means for in situ measurement of photosensitizer distribution. However, the autofluorescence of mouse tissues might potentially affect in situ photosensitizer fluorescence measurement. Objectives: The aim of this study was to evaluate the autofluorescence in lab mice and its influence on the in situ measurement of photosensitizer fluorescence. Materials and Materials and methods: ICR mice, commonly used lab animal model, were used. Mice were fed with regular diet and clean water. Domestically produced photosensitizing drug Hemoporfin® was used as a model sensitizer. Costume-built fluorescence imaging and spectroscope systems were used for fluorescence examination under the excitation wavelength of 400 ± 5 nm, generated from a laser or LED panel. In situ fluorescence was examined before and after i.v. injection of Hemoporfin®. Results: Epifluorescence imaging examination showed yellowish and reddish autofluorescence fluorescence in the mouth, nose, paws and tail areas. The absorption and emission spectra of mouse tissue overlaid to some degrees with that of Hemoporfin®. In situ fluorescence examination of ICR mice showed significant influence of autofluorescence on the spectral and intensity measurement of Hemoporfin® fluorescence. Such influence might be eliminated by post-measurement spectral correction algorithms. Conclusions: The autofluorescence in mouse tissues poses a significant influence on the in situ measurement of fluorescence emission of Hemoporfin®. Careful postmeasurement spectral correction is needed for accurately measuring photosensitizer fluorescence.
Intense pulsed light (IPL) is an incoherent high intensity pulsed light source and commonly used in dermatology and aesthetics. Early studies suggest that the combination of IPL and photosensitizer can induce cellular phototoxicity. Hemoporfin is a domestic photosensitizer approved for PDT treatment of Portwine stain birthmarks. This in vivo study evaluated the feasibility of using IPL as a light source for the excitation of Hemoporfin in mouse model. Results showed that IPL+Hemoporfin could cause more severe photodamage than IPL alone group, which suggests that it might be feasible to use IPL as PDT light source.
Background and Objectives: Area quantification has always been of research interest as it is an important step in assessing the treatment efficacy of port-wine stains (PWS) birthmarks. The objective of this study was to investigate the potential application of cellphone camera combined with manual labeling for area quantification. Materials and Methods: First, the color of the untreated PWS lesions was measured and RGB values extracted. Then, a total 48 PWS patches to represent different color, shape and size were printed. Each PWS patch was placed on a 3D head model along with a 1 cm × 1 cm size reference for photographing using a cellphone camera. The lesion region and the small white square region were determined by manual labeling method. The number of pixels within the lesion region and the small white square region were counted and the area of the PWS lesion was calculated. In addition, the image assessment was also compared with the traditional grid counting methods. Results: Each PWS patches were photographed three times. The results showed that the average error rate of the proposed digital photo scheme for the area quantization was 0.132±0.055 and the average error rate of the grid counting scheme for the area quantization was 0.004±0.005. Conclusions: Preliminary study demonstrated that the use of cellphone photo scheme to quantify the area of PWS was feasibility but its error rate was higher than that of the grid method.
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