PhD Dissertation Defense: Xitong Wang

Title: 3D Free-Breathing Self-Gated Simultaneous Cine, T1 Mapping, and Late Gadolinium Enhancement MRI for Comprehensive Cardiac Evaluation

Abstract: Cardiovascular magnetic resonance (CMR) is a reference standard for assessing cardiac structure, ventricular function, and myocardial tissue characteristics. Conventional protocols acquire cine imaging, T1 and extracellular volume (ECV) mapping, and late gadolinium enhancement (LGE) in separate breath-held, electrocardiogram (ECG)-gated scans. This workflow can be lengthy and difficult for patients with limited breath-holding capacity or irregular cardiac rhythms.

This thesis develops three-dimensional SPiral Acquisition with Respiratory correction and Cardiac Self-gating (3D SPARCS) for free-breathing cine imaging. The method combines stack-of-spirals sampling, cardiac and respiratory self-gating, motion correction, non-Cartesian reconstruction, and Deep Learning-based Rapid Spiral Image REconstruction (DESIRE). Clinical evaluation showed that 3D SPARCS could provide whole-left-ventricular cine imaging without breath-holding or ECG gating. Self-gated cardiac intervals agreed closely with ECG recordings, while DESIRE enabled rapid accelerated reconstruction. Ventricular functional measurements were compared with clinical breath-held bSSFP in complete paired datasets.

The framework was extended to 3D cine and T1 mapping using SPiral Acquisition with Respiratory and Cardiac Self-Gating (CAT-SPARCS). Paired pre- and post-contrast acquisitions can provide cine imaging, T1 and ECV mapping, and synthetic LGE during free breathing. Phantom evaluation showed strong association with reference T1 measurements and faster reconstruction using a subspace approach. Preliminary in-vivo results produced T1 maps and synthetic LGE images, with scar localization corresponding to clinical LGE in a representative case.

Together, these methods support the feasibility of reducing dependence on breath-holding and external ECG gating while retaining functional and tissue-characterization information.

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