Novel Body Magnetic Resonance Imaging Techniques

Abstract

Body magnetic resonance imaging (MRI) has progressed rapidly over the last 12 years. The advances in hardware and software have allowed the implementation of faster and better pulse sequences for body imaging. Despite the improvements in MRI technology there are still problems associated with current body MRI techniques that limit their diagnostic capabilities. The main goal of this work is to develop novel body MRI methods to improve the diagnosis of cardiac and abdominal pathologies. One of the goals of this work is to develop a technique to improve the detection of lipid infiltration in the heart. For this purpose an interleaved double-inversion fast spin-echo technique was developed. The method yields co-registered lipid and water images of the heart from data acquired in a single breath hold, producing data with optimal contrast between lipid and myocardium as well as minimal artifacts caused by chemical shift and blood flow.A technique combining GRAdient and Spin-Echo (GRASE) data acquisition and an iterative algorithm for lipid-water separation (Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation, IDEAL) was also developed. By shifting the typical GRASE data acquisition and employing correction for phase errors due to eddy currents, the IDEAL-GRASE technique achieves more time-efficient and robust lipid-water decomposition in the presence of field inhomogeneities. The technique was developed to acquire data for Cartesian and radial k-space trajectories. The radial IDEAL-GRASE with auto-correction of phase errors was developed to accomplish insensitivity to motion artifacts as well as for the generation of high resolution parametric maps (T2 and T2) for tissue characterization.A radial "variable flip angle" Steady-State Free Precession (SSFP) technique with slice profile correction was also developed to obtain fast estimation of another parameter, i.e. the T1/T2 value. This method was developed as an alternative for fast parametric imaging.These body MRI techniques were evaluated in phantoms, healthy volunteers, and patients and demonstrated for a series of applications including pelvic, cardiac, abdominal, and musculoskeletal imaging.