Elastography using optical coherence tomography : development and validation of a novel technique

Atherosclerosis is an inflammatory disease characterized by an accumulation of lipid and fibrous tissue in the arterial wall. Postmortem studies have characterized rupture-prone atherosclerotic plaques by the presence of a large lipid-rich core covered by a thin fibrous cap. Studies employing finite element analysis (FEA) based on ex vivo plaque geometry have found that most plaques rupture at sites of high circumferential stress, thus diagnosis of plaque vulnerability may be enhanced by probing the mechanical behavior of individual plaques. Elastography is a method of strain imaging in which an image sequence of the artery undergoing deformation is acquired, pixel motion is estimated between each frame, and the resulting velocity field is used to calculate strain. In this thesis, optical coherence tomography (OCT), a high-resolution optical imaging modality, is investigated as a basis for FEA and elastography of atherosclerotic plaques. FEA was performed using plaque geometries derived from both histology and OCT images of the same plaque. Patterns of mechanical stress and strain distributions computed from OCT-based models were compared with those from histology-based models, the current gold standard for FEA. The results indicate that the vascular structure and composition determined by OCT provides an adequate basis for investigating the biomechanical factors relevant to atherosclerosis. A new variational algorithm was developed for OCT elastography that improves upon the conventional algorithm by incorporating strain smoothness and incompressibility constraints into the estimation algorithm.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Chau, Alexandra H. (Alexandra Hung), 1980-

Advisor dc:contributor.advisor

• Brett Bouma.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/91380

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/91380