UCLA

Cardiovascular diseases are the leading cause of death globally and atherosclerosis is the primary underlying condition. Magnetic resonance imaging (MRI) is a promising diagnostic tool for evaluating atherosclerosis because of its excellent tissue contrast non-invasiveness. However many vascular MRI techniques have not been utilized clinically due to practical issues related to imaging speed, workflow, contrast media, and image quality. The primary focus of the work in this dissertation is to address some of these limitations and improve the capability of vascular MRI to accurately detect and characterize atherosclerotic lesions. Specifically, there are four areas of improvements of vascular MRI:

First, an online respiratory self-gating method (ADIOS) was developed for noncontrast magnetic resonance angiography of renal arteries. Some drawbacks of the conventional navigator gating method, including complicated planning and saturation artifacts were eliminated. Testing on healthy subjects confirmed that the proposed method was able to provide high-quality visualization of renal arteries with no navigator-induced artifacts, simplified setup, and shorter scan time.

Second, a diffusion-prepared turbo-spin-echo technique (DP-TSE) was developed to enable 3D high resolution diffusion weighted imaging for carotid plaque characterization without the need of contrast agent. The proposed method showed significantly higher vessel wall visibility, less distortion, and less partial volume effect. Apparent diffusion coefficient demonstrated the potential to differentiate lipid core from fibrous plaque tissue.

Third, a black-blood imaging technique (DANTE-SPACE) was developed to improve flow signal suppression in vessel wall imaging. A combined carotid and intracranial arterial wall imaging protocol was designed and tested. DANTE-SPACE demonstrated significantly improved arterial and venous blood suppression compared with conventional methods. Preliminary clinical study showed that the proposed method had the potential to detect vessel wall dissection and accurately differentiate plaque components.

Fourth, an imaging method for coronary plaque characterization was developed to allow simultaneous dark-blood T1-weighted imaging and bright-blood imaging. An image-based affine motion correction algorithm was designed to allow 100% respiratory gating efficiency. Results from healthy subjects demonstrated the feasibility of whole-heart coronary plaque imaging with isotropic high resolution. Preliminary results from patients with coronary artery disease showed the potential of this technique to detect intra-plaque hemorrhage and inflammation in the coronary wall.