NONINVASIVE MYOCARDIAL MOTION ANALYSIS WITH MRI

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DESCRIPTION: This is a proposal for the continuation of our work on myocardial motion analysis with phase contrast Magnetic Resonance Imaging (MRI) toward the ultimate goal of improved, noninvasive evaluation and management of patients with myocardial ischemia and other cardiac pathologies. We have successfully developed a technique that extracts information about myocardial dynamics from velocity maps acquired using MRI which offers many significant advantages over other currently available noninvasive methods such as ultrasound and nuclear medicine. Videofluorography of radiopaque markers and sonomicrometry, the gold standards for determination of cardiac motion due to their accuracy and their ability to study the contraction of individual myocardial samples, are responsible for much of what is known today about myocardial dynamics. However, these techniques are highly invasive and can only be used for research purposes. Another MRI method, myocardial tagging, shares with our technique the ability to measure the motion of individual regions and has already contributed basic information about myocardial physiology. Our phase contrast technique has many additional advantages, since it has the capability to readily study the entire cardiac cycle, to perform retrospective analysis, and to map 3-dimensional strain parameters throughout the heart with unprecedented spatial sampling. The proposed work is a direct extension of our accomplishments and forms a cohesive program in which we will: (1) develop multi-shot pulse sequences that are immune to artifacts from motion and other sources of data inconsistency, and that will yield in vivo performance matching the excellent capabilities demonstrated in vitro, (2) develop and test advanced methods to extract and display motion information from velocity fields, (3) validate the methods in vivo in a group of cardiac transplant patients with previously implanted radiopaque markers, and (4) test the method in animal models of myocardial ischemia (stunned myocardium and acute myocardial infarction). These experiments will demonstrate our ability to quantify both regional and global strain parameters in models of ischemic heart disease. Ultimately, the ability to monitor contractile function, combined with measurements sensitive to perfusion, should allow patients to be stratified according to risk and potential benefit of therapeutic interventions. With the successful completion of this work, we will have validated the accuracy of the technique for the noninvasive evaluation of myocardial dynamics, and will have a unique tool that can be disseminated for the study of cardiac physiology in both clinical and research MRI settings worldwide.