Time-Resolved Lower Extremity MR Angiography using HighlY Constrained Back PRojection (HYPR)

Atherosclorosis is one of the most common causes of death in the United States and throughout the world. More than 25 million persons in the United States have at least one clinical manifestation of atherosclerosis. Magnetic resonance angiography (MRA) has become technically so good that it has replaced the current gold-standard of x-ray DSA for evaluating peripheral artery disease (PAD) at many institutions. Recent advances, including those offered by our 3D TRICKs method, have made it possible to acquire time-resolved MR angiograms. This has proven very helpful in imaging the vessels of the lower extremities, but it is felt that improved temporal resolution would allow for better differentiation of arteries and veins, and would offer additional diagnostic information, especially in patients affected by asynchronous flow to contralateral limbs. We have had a recent breakthrough in time-resolved imaging with the development of a novel method we call HYPR, for HighlY constrained back PRojection. HYPR allows for dramatic increases in spatial resolution and/or temporal resolution in time-resolved MRA applications. In this study, our goal is to develop an easy-to-implement, time-resolved, multi-station, three dimensional contrast-enhanced lower extremity MRA protocol that employs HYPR to produce angiograms with very high temporal resolution, while maintaining high spatial resolution, image quality, and signal-to-noise ratio. This will require testing many modifications of the imaging method on a host of healthy volunteers and also on patients with pathology.