Quantitative colorimetry of atherosclerotic plaque using the L*a*b* color space during angioscopy for the detection of lipid cores underneath thin fibrous caps.
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.
Ishibashi
Fumiyuki
F
Center for Translational Cardiovascular Research, Tufts New England Medical Center, Boston, MA, USA.
Yokoyama
Shinya
S
Miyahara
Kengo
K
Dabreo
Alexandra
A
Weiss
Eric R
ER
Iafrati
Mark
M
Takano
Masamichi
M
Okamatsu
Kentaro
K
Mizuno
Kyoichi
K
Waxman
Sergio
S
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
D008055:Lipids