title: Discrimination between cutaneous pigmentation and erythema: comparison of the skin colorimeters Dermacatch and Mexameter.
abstract: OBJECTIVE
  Reproducibility and specificity of the present skin colorimeters is still limited as alterations in erythema can bias the measurement of melanin and vice versa. Here, Dermacatch(®) , a new colorimeter covering the visible light spectrum, has been compared with Mexameter(®) , an established narrow-band reflectance spectrophotometer.
  
  
  METHODS
  Repeated measurements with both devices were initially collected on colour charts. Then, measures were compared on 12 human volunteers before and after exposure to UVB, and/or modulation of skin erythema.
  
  
  RESULTS
  In vitro sensitivity of Dermacatch to erythema/melanin covered a broader wavelength spectrum than Mexameter while in vivo sensitivity of both devices was similar. Interestingly, Mexameter's melanin and erythema values were falsely affected by an increase in erythema or variation in pigmentation respectively. On the contrary, Dermacatch's melanin and erythema values remained constant in the same circumstances. Furthermore, as Mexameter was at least twice less reproducible than Dermacatch, Mexameter showed an increased risk of a confusion over the detection of erythema or melanin fluctuations.
  
  
  CONCLUSIONS
  The analysis of more than 18,000 measures indicated that, Dermacatch has a significantly higher specificity and reproducibility than Mexameter in the measurement of skin pigmentation and erythema.
authors.affiliation: Scientis Pharma, Geneva, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Baquié
authors.forename: B
authors.initials: B
authors.lastname: Kasraee
mesh_terms: D003124:Colorimetry / Q000295:instrumentation*; D046169:Dermoscopy / Q000295:instrumentation*; D016002:Discriminant Analysis; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004890:Erythema / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation; D008297:Male; D010859:Pigmentation Disorders / Q000473:pathology*; D010860:Pigments, Biological / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012867:Skin / Q000473:pathology*; D012880:Skin Pigmentation; D013053:Spectrophotometry / Q000295:instrumentation*; D055815:Young Adult
chemical_list: D010860:Pigments, Biological
keywords: Chromameter; Mexameter; colorimeter; erythema; melanin; quantification of skin colour; reflectance colorimetry; skin colour