title: Classification of ultraviolet irradiated mouse skin histological stages by bimodal spectroscopy: multiple excitation autofluorescence and diffuse reflectance.
abstract: Histopathological analysis and in vivo optical spectroscopy were used to discriminate several histological stages of UV-irradiated mouse skin. At different times throughout the 30-week irradiation, autofluorescence (AF) and diffuse reflectance (DR) spectra were acquired in a bimodal approach. Then skin was sampled and processed to be classified, according to morphological criteria, into four histological categories: normal, and three types of hyperplasia (compensatory, atypical, and dysplastic). After extracting spectral characteristics, principal component analysis (data reduction) and the k-nearest neighbor classifying method were applied to compare diagnostic performances of monoexcitation AF (based on each of the seven excitation wavelengths: 360, 368, 390, 400, 410, 420, and 430 nm), multiexcitation AF (combining the seven excitation wavelengths), DR, and bimodal spectroscopies. Visible wavelengths are the most sensitive ones to discriminate compensatory from precancerous (atypical and dysplastic) states. Multiexcitation AF provides an average 6-percentage-point increased sensitivity compared to the best scores obtained with monoexcitation AF for all pairs of tissue categories. Bimodality results in a 4-percentage-point increase of specificity when discriminating the three types of hyperplasia. Thus, bimodal spectroscopy appears to be a promising tool to discriminate benign from precancerous stages; clinical investigations should be carried out to confirm these results.
authors.affiliation: Nancy-University, Centre de Recherche en Automatique de Nancy, CRAN UMR 7039 CNRS, 2 avenue de la Foreet de Haye, 54516 Vandoeuvre-les-Nancy cedex, France.
authors.forename: Marine
authors.initials: M
authors.lastname: Amouroux
authors.forename: Gilberto
authors.initials: G
authors.lastname: Díaz-Ayil
authors.forename: Walter C P M
authors.initials: WC
authors.lastname: Blondel
authors.forename: Geneviève
authors.initials: G
authors.lastname: Bourg-Heckly
authors.forename: Agnès
authors.initials: A
authors.lastname: Leroux
authors.forename: François
authors.initials: F
authors.lastname: Guillemin
mesh_terms: D000465:Algorithms; D000818:Animals; D046169:Dermoscopy / Q000379:methods; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D051379:Mice; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D009367:Neoplasm Staging / Q000379:methods; D009381:Neoplasms, Radiation-Induced / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000473:pathology*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014466:Ultraviolet Rays