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Proceedings Paper

Characterization of atherosclerotic plaque by reflection spectroscopy and thermography: a comparison
Author(s): Magnus B. Lilledahl; Olav A. Haugen; Lise Lyngsnes Randeberg; Lars Othar Svaasand
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Paper Abstract

Many methods for detecting and measuring vulnerable atherosclerotic plaques have been proposed. These include reflection spectroscopy, thermography, ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). This paper presents an analysis and a comparison of two of these methods, near-infrared reflection spectroscopy (NIRS) and thermography. Most of the published literature evaluate methods statistically. A more analytic approach will make it easier to compare the different methods and determine if the measured signal will be strong enough in a real measurement situation. This is the approach taken in this article. Eight samples of human aorta were examined by NIRS and subsequently prepared for histology. A total of 28 measurement points were selected. A measure of the lipid content based on reflection spectra is proposed. Comparisons of this lipid measure with histology show that the lipid content in the plaques yields relatively small changes in the value of this lipid-index. Reflectance spectra from models based on the diffusion approximation for total reflectance were simulated. Temperature measurements were performed on three Watanabe heritable hyperlipidemic (WHHL) rabbits and one New Zealand white (NZW) rabbit with a thermistor-type intravascular temperature sensor. The measurements gave no significant signals which correlated with the subsequent histology. A simple analytic model was developed which indicates that a temperature increase of more than 0.01-0.04 °C at the surface of a vessel wall, due to inflammation in a plaque, is unlikely. Such a small temperature difference will probably be obscured by normal variation in the vessel wall temperature.

Paper Details

Date Published: 25 April 2005
PDF: 11 pages
Proc. SPIE 5686, Photonic Therapeutics and Diagnostics, (25 April 2005); doi: 10.1117/12.586548
Show Author Affiliations
Magnus B. Lilledahl, Norwegian Univ. of Science and Technology (Norway)
Olav A. Haugen, Norwegian Univ. of Science and Technology (Norway)
St. Olav's Univ. Hospital (Norway)
Lise Lyngsnes Randeberg, Norwegian Univ. of Science and Technology (Norway)
Lars Othar Svaasand, Norwegian Univ. of Science and Technology (Norway)

Published in SPIE Proceedings Vol. 5686:
Photonic Therapeutics and Diagnostics
Brian Jet-Fei Wong M.D.; Eugene A. Trowers M.D.; Kenton W. Gregory M.D.; Abraham Katzir; Nikiforos Kollias; Reza S. Malek M.D.; Henry Hirschberg M.D.; Kenneth Eugene Bartels D.V.M.; Steen J. Madsen; Lloyd P. Tate V.D.M.; Lawrence S. Bass M.D.; Werner T. W. de Riese; Karen M. McNally-Heintzelman, Editor(s)

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