Abstract
Objectives
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 μm).
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.
Similar content being viewed by others
Abbreviations
- ACS:
-
Acute coronary syndromes
- A/D:
-
Analog to digital
- CCD:
-
Charge-coupled device
- CIE:
-
International Committee on Illumination
- HIS:
-
Hue, saturation, intensity
- LCTC:
-
Lipid core underneath thin fibrous cap
- NTSC:
-
National Television System Committee
- POI:
-
Point of interest
- RGB:
-
Red, green, blue
- ROI:
-
Region of interest
- SD:
-
Standard deviation
References
Falk E (2006) Pathogenesis of atherosclerosis. J Am Coll Cardiol 47:C7–C12
Waxman S, Ishibashi F, Muller JE (2006) Detection and treatment of vulnerable plaques and vulnerable patients: novel approaches to prevention of coronary events. Circulation 114:2390–2411
Thieme T, Wernecke KD, Meyer R et al (1996) Angioscopic evaluation of atherosclerotic plaques: validation by histomorphologic analysis and association with stable and unstable coronary syndromes. J Am Coll Cardiol 28:1–6
Uchida Y, Nakamura F, Tomaru T et al (1995) Prediction of acute coronary syndromes by percutaneous coronary angioscopy in patients with stable angina. Am Heart J 130:195–203
Mizuno K, Miyamoto A, Satomura K et al (1991) Angioscopic coronary macromorphology in patients with acute coronary disorders. Lancet 337:809–812
Waxman S, Sassower M, Mittleman M et al (1996) Angioscopic predictors of early adverse outcome following coronary angioplasty in patients with unstable angina and non-Q wave myocardial infarction. Circulation 93:2106–2113
Waxman S, Mittleman MA, Zarich SW et al (1997) Angioscopic assessment of coronary lesions underlying thrombus. Am J Cardiol 79:1106–1109
den Heijer PJ, Foley DP, Hillege HL et al (1994) The “Ermenonville” classification of observations at coronary angioscopy: evaluation of intra-and inter-observer agreement. European Working Group on Coronary Angioscopy. Eur Heart J 15:815–818
Lehmann KG, Oomen JA, Slager CJ et al (1998) Chromatic distortion during angioscopy: assessment and correction by quantitative colorimetric angioscopic analysis. Cathet Cardiovasc Diagn 45:191–201
Lehmann KG, van Suylen RJ, Stibbe J et al (1997) Composition of human thrombus assessed by quantitative colorimetric angioscopic analysis. Circulation 96:3030–3041
Miyamoto A, Prieto AR, Friedl SE et al (2004) Atheromatous plaque cap thickness can be determined by quantitative color analysis during angioscopy: implications for identifying the vulnerable plaque. Clin Cardiol 27:9–15
Stary HC, Chandler AB, Dinsmore RE et al (1995) A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association. Circulation 92:1355–1374
Takano M, Mizuno K, Okamatsu K et al (2001) Mechanical and structural characteristics of vulnerable plaques: analysis by coronary angioscopy and intravascular ultrasound. J Am Coll Cardiol 38:99–104
Asakura M, Ueda Y, Yamaguchi O et al (2001) Extensive development of vulnerable plaques as a pan-coronary process in patients with myocardial infarction: an angioscopic study. J Am Coll Cardiol 37:1284–1288
Takano M, Mizuno K, Yokoyama S et al (2003) Changes in coronary plaque color and morphology by lipid-lowering therapy with atorvastatin: serial evaluation by coronary angioscopy. J Am Coll Cardiol 42:680–686
Blankenhorn DH, Freiman DG, Knowle HC (1956) Cartenoids in man: the distribution of epiphasic cartenoids in atherosclerotic lesions. J Clin Invest 35:1243–1247
Kawasaki M, Takatsu H, Noda T et al (2002) In vivo quantitative tissue characterization of human coronary arterial plaques by use of integrated backscatter intravascular ultrasound and comparison with angioscopic findings. Circulation 105:2487–2492
Virmani R, Kolodgie FD, Burke AP et al (2000) Lessons from sudden coronary death: a comprehensive morphological classification scheme for atherosclerotic lesions. Arterioscler Thromb Vasc Biol 20:1262–1275
Fernandez-Ortiz A, Badimon JJ, Falk E et al (1994) Characterization of the relative thrombogenicity of atherosclerotic plaque components: implications for consequences of plaque rupture. J Am Coll Cardiol 23:1562–1569
Kienle A, Lilge L, Vitkin IA et al (1996) Why do veins appear blue? A new look as an old question. Appl Optics 35:1151–1160
Kockx MK, Cromheeke KM, Knaapen MWM et al (2003) Phagocytosis and macrophage activation associated with hemorrhagic microvessels in human atherosclerosis. Arterioscler Thromb Vasc Biol 23:440–446
Kurita A, Ishizuka T, Matsui T et al (2004) Significance of angioscopic morphology for the estimation of macrophage infiltration and vascular physiology. Int J Cardiovasc Imag 20:165–171
Ishibashi F, Aziz K, Abela GS et al (2006) Update on coronary angioscopy: review of a 20-year experience and potential application for detection of vulnerable plaque. J Intervent Cardiol 19:17–25
Acknowledgements
This study was supported in part by Research Grants from Fukuda Kinenn Foundation (to F.I) and for Cardiovascular Disease (15-5) from The Japanese Ministry of Health, Labor and Welfare (to K.M).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Ishibashi, F., Yokoyama, S., Miyahara, K. et al. Quantitative colorimetry of atherosclerotic plaque using the L*a*b* color space during angioscopy for the detection of lipid cores underneath thin fibrous caps. Int J Cardiovasc Imaging 23, 679–691 (2007). https://doi.org/10.1007/s10554-007-9212-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10554-007-9212-1