Evaluation of illumination wavelengths for fluorescence detection of atherosclerosis.

Persistent Link:
http://hdl.handle.net/10150/186607
Title:
Evaluation of illumination wavelengths for fluorescence detection of atherosclerosis.
Author:
Alexander, Andrew Lafayette.
Issue Date:
1994
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The fluorescence-emission spectra of normal arterial tissues and atherosclerotic plaques are distinct. The fluorescence spectra of arterial tissues are also dependent on the illumination wavelength. Which illumination wavelengths are best for identifying arterial tissues? To answer this question, a system for measuring fluorescence spectra at different illumination wavelengths was constructed and the fluorescence spectra of in-vitro aorta specimens were acquired with several illumination wavelengths between 270 nm and 500 nm. The Mahalanobis distance, a statistical measure of separability between two class density-distributions, was used to compare spectral features of normal vessel and atherosclerotic plaques at each of the illumination wavelengths. The Mahalanobis distance results indicated that the separability was largest for illumination wavelengths in the 314 nm to 334 nm range. In addition, the atherosclerotic plaque class was further subdivided into three diseased subclasses--fibrous plaques, complicated plaques and hard calcified plaques. The largest Mahalanobis distance between normal vessel and soft plaque (fibrous plaque and complicated plaque) again occurred with illumination in the wavelength range 314 nm to 334 nm. Conversely, the hard-calcified plaque class was most separable from the normal vessel class with illumination wavelengths longer than 380 nm. Since the best illumination wavelength ranges for soft plaques and hard calcified plaques were different, tissue identification was evaluated for the three-class case--normal artery versus soft plaques versus calcified plaques. Analysis with the generalized multiple-discriminant measure, a multiple-class extension of the Mahalanobis distance, indicated that illumination in the 300 nm to 314 nm range and the 400 nm to 458 nm range had the greatest three-class separability. Several multiple-class classifiers were also evaluated at each illumination wavelength. These classifiers did not reveal any wavelengths that were clearly best for accurate tissue-type identification. Finally, class separability and classification performance of combined features from multiple illumination wavelengths were also examined. The combination of features from multiple illumination wavelengths was found to increase separability and to improve the overall classification capability.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic.; Optics.; Biomedical engineering.; Statistics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Optical Sciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Gmitro, Arthur F.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleEvaluation of illumination wavelengths for fluorescence detection of atherosclerosis.en_US
dc.creatorAlexander, Andrew Lafayette.en_US
dc.contributor.authorAlexander, Andrew Lafayette.en_US
dc.date.issued1994en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe fluorescence-emission spectra of normal arterial tissues and atherosclerotic plaques are distinct. The fluorescence spectra of arterial tissues are also dependent on the illumination wavelength. Which illumination wavelengths are best for identifying arterial tissues? To answer this question, a system for measuring fluorescence spectra at different illumination wavelengths was constructed and the fluorescence spectra of in-vitro aorta specimens were acquired with several illumination wavelengths between 270 nm and 500 nm. The Mahalanobis distance, a statistical measure of separability between two class density-distributions, was used to compare spectral features of normal vessel and atherosclerotic plaques at each of the illumination wavelengths. The Mahalanobis distance results indicated that the separability was largest for illumination wavelengths in the 314 nm to 334 nm range. In addition, the atherosclerotic plaque class was further subdivided into three diseased subclasses--fibrous plaques, complicated plaques and hard calcified plaques. The largest Mahalanobis distance between normal vessel and soft plaque (fibrous plaque and complicated plaque) again occurred with illumination in the wavelength range 314 nm to 334 nm. Conversely, the hard-calcified plaque class was most separable from the normal vessel class with illumination wavelengths longer than 380 nm. Since the best illumination wavelength ranges for soft plaques and hard calcified plaques were different, tissue identification was evaluated for the three-class case--normal artery versus soft plaques versus calcified plaques. Analysis with the generalized multiple-discriminant measure, a multiple-class extension of the Mahalanobis distance, indicated that illumination in the 300 nm to 314 nm range and the 400 nm to 458 nm range had the greatest three-class separability. Several multiple-class classifiers were also evaluated at each illumination wavelength. These classifiers did not reveal any wavelengths that were clearly best for accurate tissue-type identification. Finally, class separability and classification performance of combined features from multiple illumination wavelengths were also examined. The combination of features from multiple illumination wavelengths was found to increase separability and to improve the overall classification capability.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academic.en_US
dc.subjectOptics.en_US
dc.subjectBiomedical engineering.en_US
dc.subjectStatistics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineOptical Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairGmitro, Arthur F.en_US
dc.contributor.committeememberDallas, Williamen_US
dc.contributor.committeememberFranken, Peteren_US
dc.identifier.proquest9424940en_US
dc.identifier.oclc722411189en_US
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