title: Quantification of allergic and irritant patch test reactions using ImageJ.
abstract: OBJECTIVE
  It is often difficult to differentiate between allergic and irritant patch test reactions by visual inspection. The purpose of this study was to test an image analysis-based method that differentiates between the two reactions by quantifying the degree of erythema at the patch test site.
  
  
  METHODS
  A total of 172 Japanese patients were patch-tested with sodium lauryl sulfate (SLS) and nickel sulfate, followed by digital photography and visual evaluation of the patch test areas by dermatologists at 48 and 72 h. The digital images were converted to erythema index (EI) images by image processing, and changes in ΔEI (the difference in the EI between the patch test site and the adjacent normal skin) values were analyzed.
  
  
  RESULTS
  The ΔEI was significantly increased at 72 h relative to that at 48 h for positive nickel sulfate reactions (P < 0.0001), while no significant difference in the ΔEI was found for SLS reactions.
  
  
  CONCLUSIONS
  Using image analysis, allergic patch test reactions may be distinguished from irritant reactions by evaluating the change in the degree of erythema at 48 and 72 h.
authors.affiliation: POLA Laboratories, POLA Chemical Industries Inc, Totsuka-ku, Yokohama, Japan; Department of Dermatology, School of Medicine, Toho University, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohshima
authors.forename: S
authors.initials: S
authors.lastname: Kinoshita
authors.forename: M
authors.initials: M
authors.lastname: Futagawa
authors.forename: H
authors.initials: H
authors.lastname: Takiwaki
authors.forename: K
authors.initials: K
authors.lastname: Washizaki
authors.forename: A
authors.initials: A
authors.lastname: Ishiko
authors.forename: H
authors.initials: H
authors.lastname: Kanto
mesh_terms: D000485:Allergens; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis*; D046169:Dermoscopy / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007509:Irritants; D008297:Male; D008875:Middle Aged; D009532:Nickel; D015588:Observer Variation; D010328:Patch Tests / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012967:Sodium Dodecyl Sulfate
chemical_list: D000485:Allergens; D007509:Irritants; D012967:Sodium Dodecyl Sulfate; C029938:nickel sulfate; D009532:Nickel
keywords: ICDRG; allergic; erythema index; image processing; irritant