title: Comparison of tissue viability imaging and colorimetry: skin blanching.
abstract: BACKGROUND
  Operator-independent assessment of skin blanching is important in the development and evaluation of topically applied steroids. Spectroscopic instruments based on hand-held probes, however, include elements of operator dependence such as difference in applied pressure and probe misalignment, while laser Doppler-based methods are better suited for demonstration of skin vasodilatation than for vasoconstriction.
  
  
  OBJECTIVE
  To demonstrate the potential of the emerging technology of Tissue Viability Imaging (TiVi) in the objective and operator-independent assessment of skin blanching.
  
  
  METHODS
  The WheelsBridge TiVi600 Tissue Viability Imager was used for quantification of human skin blanching with the Minolta chromameter CR 200 as an independent colorimeter reference method. Desoximetasone gel 0.05% was applied topically on the volar side of the forearm under occlusion for 6 h in four healthy adults. In a separate study, the induction of blanching in the occlusion phase was mapped using a transparent occlusion cover.
  
  
  RESULTS
  The relative uncertainty in the blanching estimate produced by the Tissue Viability Imager was about 5% and similar to that of the chromameter operated by a single user and taking the a(*) parameter as a measure of blanching. Estimation of skin blanching could also be performed in the presence of a transient paradoxical erythema, using the integrated TiVi software. The successive induction of skin blanching during the occlusion phase could readily be mapped by the Tissue Viability Imager.
  
  
  CONCLUSIONS
  TiVi seems to be suitable for operator-independent and remote mapping of human skin blanching, eliminating the main disadvantages of methods based on hand-held probes.
authors.affiliation: Department of Dermatology, School of Medicine, University of California, San Francisco, CA, USA.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Zhai
authors.forename: Heidi P
authors.initials: HP
authors.lastname: Chan
authors.forename: Sara
authors.initials: S
authors.lastname: Farahmand
authors.forename: Gert E
authors.initials: GE
authors.lastname: Nilsson
authors.forename: Howard I
authors.initials: HI
authors.lastname: Maibach
mesh_terms: D003124:Colorimetry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004906:Erythrocyte Count / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012867:Skin / Q000098:blood supply* / Q000737:chemistry*; D012880:Skin Pigmentation / Q000502:physiology*; D014022:Tissue Survival / Q000502:physiology