title: In vivo characterization of human pigmented lesions by degree of linear polarization image maps using incident linearly polarized light.
abstract: OBJECTIVE
  Melanoma is the most serious form of skin cancer and often appears as an evolving multicolored skin growth. It is well documented that pre-existing atypical or dysplastic nevi can evolve into a melanoma. The development of an in vivo imaging system to characterize benign and malignant nevi has been emphasized to aid in early detection of melanoma. The goal of this study is to utilize a novel Stokes polarimetry imaging (SPI) system for the characterization of pigmented lesions, and to evaluate the SPI system in comparison to dermoscopy and histology images.
  
  
  METHODS
  Linearly polarized light with varying incident polarization angles (IPA) illuminated various types of pigmented lesions. The melanocytic nesting patterns of pigmented lesions were characterized by constructing the degree-of-linear-polarization (DOLP) image map with comparison to dermoscopy and histology. The incident polarized light was filtered by visible filters for spectral imaging and incident deeply penetrating red light was used to correlate the SPI image with histopathological examination.
  
  
  RESULTS
  The DOLP images with varying IPA at different visible wavelengths were used to characterize various kinds of pigmented lesions by showing subsurface melanocytic nesting distribution as well as morphological information with better resolution and contrast. In correlation with dermoscopy and histology, various defining features such as compound, junctional, lentiginous, reticular, globular patterns of melanocytic nests were identified.
  
  
  CONCLUSIONS
  When imaging pigmented melanocytic lesions, the SPI system with varying IPA at the red light wavelength can better define the melanocytic nesting patterns in both the dermal epidermal junction and the dermis. The SPI system has the potential to be an effective in vivo method of detecting pre-malignant nevi and melanoma.
authors.affiliation: Biomedical Engineering Department, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Jihoon
authors.initials: J
authors.lastname: Kim
authors.forename: Raheel
authors.initials: R
authors.lastname: John
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Wu
authors.forename: Mary C
authors.initials: MC
authors.lastname: Martini
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Walsh
mesh_terms: D015331:Cohort Studies; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008859:Microscopy, Polarization; D009508:Nevus, Pigmented / Q000175:diagnosis*; D055096:Optical Devices; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D057109:Scanning Laser Polarimetry / Q000295:instrumentation*; D012878:Skin Neoplasms / Q000175:diagnosis*