title: Quantitative colorimetry of atherosclerotic plaque using the L*a*b* color space during angioscopy for the detection of lipid cores underneath thin fibrous caps.
abstract: OBJECTIVE
  Yellow plaques seen during angioscopy are thought to represent lipid cores underneath thin fibrous caps (LCTCs) and may be indicative of vulnerable sites. However, plaque color assessment during angioscopy has been criticized because of its qualitative nature. The purpose of the present study was to test the ability of a quantitative colorimetric system to measure yellow color intensity of atherosclerotic plaques during angioscopy and to characterize the color of LCTCs.
  
  
  METHODS
  Using angioscopy and a quantitative colorimetry system based on the L*a*b* color space [L* describes brightness (-100 to +100), b* describes blue to yellow (-100 to +100)], the optimal conditions for measuring plaque color were determined in three flat standard color samples and five artificial plaque models in cylinder porcine carotid arteries. In 88 human tissue samples, the colorimetric characteristics of LCTCs were then evaluated.
  
  
  RESULTS
  In in-vitro samples and ex-vivo plaque models, brightness L* between 40 and 80 was determined to be optimal for acquiring b* values, and the variables unique to angioscopy in color perception did not impact b* values after adjusting for brightness L* by manipulating light or distance. In ex-vivo human tissue samples, b* value >/=23 (35.91 +/- 8.13) with L* between 40 and 80 was associated with LCTCs (fibrous caps <100 mum).
  
  
  CONCLUSIONS
  Atherosclerotic plaque color can be consistently measured during angioscopy with quantitative colorimetry. High yellow color intensity, determined by this system, was associated with LCTCs. Quantitative colorimetry during angioscopy may be used for detection of LCTCs, which may be markers of vulnerability.
authors.affiliation: Center for Translational Cardiovascular Research, Tufts New England Medical Center, Boston, MA, USA.
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Ishibashi
authors.forename: Shinya
authors.initials: S
authors.lastname: Yokoyama
authors.forename: Kengo
authors.initials: K
authors.lastname: Miyahara
authors.forename: Alexandra
authors.initials: A
authors.lastname: Dabreo
authors.forename: Eric R
authors.initials: ER
authors.lastname: Weiss
authors.forename: Mark
authors.initials: M
authors.lastname: Iafrati
authors.forename: Masamichi
authors.initials: M
authors.lastname: Takano
authors.forename: Kentaro
authors.initials: K
authors.lastname: Okamatsu
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Mizuno
authors.forename: Sergio
authors.initials: S
authors.lastname: Waxman
mesh_terms: D017546:Angioscopy; D000818:Animals; D050197:Atherosclerosis / Q000473:pathology*; D003124:Colorimetry / Q000379:methods; D003331:Coronary Vessels / Q000473:pathology*; D006801:Humans; D066298:In Vitro Techniques; D008055:Lipids / Q000032:analysis; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D013552:Swine
chemical_list: D008055:Lipids