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Non-contrast-enhanced magnetic resonance imaging and computational fluid dynamics for carotid atherosclerosis

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thesis
posted on 28.03.2022, 11:35 by Jonas Groschwitz
Atherosclerotic plaques of the carotid artery are considered to be one of the major risk factors for stroke. To efficiently and precisely characterise the major plaque components, a new magnetic resonance imaging (MRI) sequence has therefore been promoted in this project. Besides plaque components, haemodynamics also plays a critical role in the progress and rupture of atherosclerotic plaques. Therefore, a new methodology that combines computational fluid dynamics (CFD) with non-contrast-enhanced magnetic resonance angiography (MRA) has been developed in this study to provide quantitative haemodynamic analysis for the diagnosis of carotid atherosclerosis and assessment of the outcomes of surgery. In the first part of this research, a newly-developed plaque sequence termed 'MATCH' is introduced. The MATCH sequence has the advantages of short acquisition time and ability to identify plaque components. The MATCH sequence has been utilised to characterise the major plaque components, which include intraplaque haemorrhage (IPH), a large lipid-rich necrotic core, loose matrix, and calcification. The performance of MATCH in differentiating plaque components was compared with that of conventional multi-contrast MRI and confirmed by histological evidence in this study. The results indicate that the MATCH was comparable if not superior to conventional protocol in identification and quantification of major carotid plaque components. In the second part, the relationship between haemodynamics and carotid plaques with IPH was investigated. We hypothesised that haemodynamics plays a pivotal role in the development of IPH. For this purpose, the maximum wall shear stress (mWSS) at the surface of plaques was compared for the groups with and without IPH under different severities of carotid artery stenosis. The results demonstrated that the higher mWSS was exhibited in carotids with IPH for cases with stenosis less than 70%, and the magnitude of mWSS was positively correlated with the volume of IPH. However, there was no significant relationship between mWSS and IPH when the stenosis exceeded 70%. Our results indicate that mWSS i a promising parameter to evaluate plaque vulnerability for carotids with stenosis of less than70%. In the last part of this thesis, CFD simulation was performed to analyse blood flow changes after carotid endarterectomy (CEA). The morphological characteristics and haemodynamic parameters were compared before and after CEA, as well as for healthy carotids as a control group. The major haemodynamic parameters were restored after surgery in short-term followup. This study indicates that CFD analysis can provide valuable information for the evaluation of physiological functions after CEA.

History

Table of Contents

Chapter 1. Introduction -- Chapter 2. Literature review -- Chapter 3. Imaging techniques for carotid atherosclerosis -- Chapter 4. New MRI sequence for the analysis of atherosclerotic plaques - Multicontrast Atherosclerosis Characterization (MATCH) -- Chapter 5. Computational fluid dynamics techniques and applications for cerebrovascular diseases -- Chapter 6. Associations between local haemodynamics and carotid intraplaque haemorrhage with different stenosis severities -- Chapter 7. Haemodynamic analysis of carotid artery after endarterectomy -- Chapter 8. Conclusions and future directions -- Ethics approval.

Notes

Bibliography: pages 223-230 Empirical thesis.

Awarding Institution

Macquarie University

Degree Type

Thesis PhD

Degree

PhD, Macquarie University, Faculty of Medicine and Health Sciences, Department of Biomedical Sciences

Department, Centre or School

Department of Biomedical Sciences

Year of Award

2019

Principal Supervisor

Itsu Sen

Additional Supervisor 1

Jiang Lin

Rights

Copyright Yuanyuan Dai 2019. Copyright disclaimer: http://mq.edu.au/library/copyright

Language

English

Jurisdiction

Australia

Extent

1 online resource (181 pages) illustrations

Former Identifiers

mq:72228 http://hdl.handle.net/1959.14/1282686