Coronary magnetic resonance angiography (CMRA) is a potential diagnostic tool for coronary artery disease (CAD). Compared to the current gold standard, x-ray angiography, CMRA provides three-dimensional visualization of coronary vessel lumens without the use of catheters and ionizing radiation. CMRA, however, requires long acquisition times that span multiple heartbeats. Typically, to reduce cardiac motion artifacts, electrocardiogram (ECG) gating is used to synchronize data acquisition windows to diastasis periods. Gating errors may cause vessel blurring by unintentionally triggering the scanner to acquire image data during periods of significant cardiac motion. This is particularly problematic for CMRA because of the associated fine spatial resolution requirement for diagnosing CAD.
This thesis presents and tests the novel idea of determining the timing of global epicardial diastasis periods from the motion of the basal ventricular septum. An experiment involving a small patient cohort undergoing elective diagnostic angiography revealed a significant correlation between the beat-to-beat diastasis periods of the ventricular septum and the coronary vasculature. This motivated the
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development and testing of the hypothesis that suggests sharper coronary artery images may be obtained by using cardiac gating windows determined by septal motion. A preliminary study involving a small volunteer cohort provided encouraging results, but also revealed limitations of using ultrasound to measure septal motion during a pre- scan prior to an MRA exam. This led to the major technical development of this thesis, which is a magnetic resonance imaging (MRI) method called the Septal Scout for monitoring septal motion at a very high temporal resolution. The technique was applied to a volunteer cohort which showed that cardiac gating windows as determined by the Septal Scout provided sharper coronary images compared with conventional ECG gating.
The scientific knowledge and technical developments presented in this thesis are intended to improve CMRA as a non-invasive diagnostic tool of CAD. In the future, I intend to integrate the concepts presented here into a functioning MRI-based cardiac gating system. As well, I intend to validate the Septal Scout in a patient cohort study.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/65682 |
| Date | 22 July 2014 |
| Creators | Liu, Garry |
| Contributors | Wright, Graham |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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