A New Approach for the Assessment of Allergic Dermatitis Using LongWavelength Near-Infrared Spectral Imaging

摘要

Imaging devices for long-wavelength near-infrared lightrn(e.g., MCT, InGaAs) and hyperspectral imaging devices usingrnthese wavelengths have recently been developed. This range ofrnwavelengths is especially effective for measuring the compositionrnof objects because it includes the absorption spectra of molecularrnvibrations. In this study, long-wavelength near-infrared spectralrnimaging was used to evaluate allergic dermatitis. Allergic dermatitisrncan be caused by 2 types of hypersensitivity, immediatern(type Ⅰ) and delayed (type Ⅳ), which are activated by differentrnmechanisms. However, both types of dermatitis are characterizedrnby erythema and localized tissue swelling of the affected area, andrnit is therefore difficult to determine the type of allergic responsernby macroscopic inspection. Near-infrared spectral imaging hasrnattracted attention as a non-destructive inspection method, butrnwhile several studies have focused on the detection of edemarnby near-infrared spectroscopy, the previously reported methodsrnhave not attempted to differentiate between different types of allergicrndermatitis by detecting intracutaneous targets specific tornthe different activation mechanisms. This study aimed to developrna method for the assessment of allergic dermatitis by using thernlong-wavelength near-infrared spectrum to detect intracutaneousrnallergic type-specific targets. Such a method was realized by establishingrna spectral classifier for the spectra of type Ⅰ and typernⅣ allergic dermatitis reactions. A spectral classifier was establishedrnfrom the spectral datasets of histamine-induced cutaneousrnreaction (immediate type) and contact hypersensitivity erythemarnelicited by squaric acid dibutylester (SADBE; type Ⅳ), and arncanonical discriminant analysis achieved very accurate detectionrnof normal skin and types Ⅰ and Ⅳ allergic dermatitis (normal skin:rn87.2%, histamine induced reaction: 71.0%, SADBE contact hypersensitivity:rn95.8%). The classifier was next applied to spectralrnimages of 2 other skin conditions, red flare activated by methylrnnicotinate (normal skin) and metal allergy (type Ⅳ), and thesernvalidation datasets were also correctly classified: the red flare inducedrnby methyl nicotinate was categorized as normal skin andrnthe contact hypersensitivity activated by the metal allergy patchrntest was categorized as a type Ⅳ allergic reaction. These resultsrnsuggest a possible application of near-infrared spectral imagingrnto the assessment of allergic dermatitis.