In vivo near-infrared autofluorescence imaging of pigmented skin lesions: methods, technical improvements and preliminary clinical results.
OBJECTIVE
Fluorescence emission from in vivo cutaneous melanin was recently detected under near-infrared (NIR) excitation by our group. We then built a prototype NIR autofluorescence imaging system to observe and characterize the melanin distribution in human skin. In this article, we reported a new setup of NIR fluorescence imaging system and calibration methods to optimize the system for better clinical feasibility and clearer image.


METHODS
The imaging system was designed to perform both fluorescence and reflectance imaging with a 785-nm fiber-coupled laser source. The illumination light was purified by a 785-nm bandpass filter for fluorescence excitation; while the spontaneous components were selected by a longpass filter for NIR reflectance imaging. A hand-controlled filter wheel was used to switch these two filters for different imaging modes. A dichroic filter was used to guide the illuminating light onto the skin surface for excitation. Reflectance and fluorescence signals were collected sequentially by a NIR optimized CCD camera. The captured images were calibrated by the reflectance images of a standard reflectance disk for non-uniform illuminations and light collection efficiencies.


RESULTS
The clinical results demonstrated that NIR fluorescence intensities and distribution patterns vary among lesion types. It was also confirmed that pigmented skin lesions emitted higher NIR fluorescence than the surrounding normal skin due to the presentation of higher concentrations of cutaneous melanin within the lesions.


CONCLUSIONS
NIR autofluorescence imaging system could be utilized as a powerful tool for visualizing melanin distribution in pigmented skin lesions and as a potential method for aiding melanoma detection.
Imaging Unit - Integrative Oncology Department, British Columbia Cancer Agency Research Centre, Vancouver, BC, Canada.
Shuang
S
Wang
Jianhua
J
Zhao
Harvey
H
Lui
Qingli
Q
He
Haishan
H
Zeng
D002138:Calibration; D046169:Dermoscopy / Q000295:instrumentation / Q000379:methods*; D003937:Diagnosis, Differential; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D017492:Keratosis, Seborrheic / Q000378:metabolism / Q000473:pathology; D008297:Male; D008543:Melanins / Q000378:metabolism; D008545:Melanoma / Q000378:metabolism / Q000473:pathology*; D018329:Nevus, Blue / Q000378:metabolism / Q000473:pathology; D018330:Nevus, Intradermal / Q000378:metabolism / Q000473:pathology; D061848:Optical Imaging / Q000295:instrumentation / Q000379:methods*; D010865:Pilot Projects; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*; D012880:Skin Pigmentation; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation / Q000379:methods*; D014820:Vitiligo / Q000378:metabolism / Q000473:pathology
D008543:Melanins