DEVELOPMENT OF A NEW MRI METHOD TO STUDY CARDIAC MOTION

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Heart well motion is of great clinical interest, and many different techniques have been employed to study it, all with significant limitations and/or risks. The goal of this project is to develop a new, noninvasive, methods for studying the motion of the heart, using magnetic resonance imaging (MRI), which offers significant advantages relative to previously available methods. The specific aims of this application are to focus on the technical aspects of this method: 1) developing the method itself, 2) developing means for analyzing the data it can produce, 3) developing means for displaying the results of this analysis and 4) validating the results. We also will use this technique to obtain data on contraction of the normal heart. The broader, more long-term objectives are to use this new method as a toll for further research, both in investigations of cardiac physiology and in clinical studies of the effects of heart disease, such as myocardial infarction and ischemia and cardiomyopathies, on cardiac motion, The ultimate goal is to improve our abilities to diagnose heart disease and to monitor its therapy. The basic technique, which produces a pattern of magnetically tagged stripes in the myocardium that can be used to noninvasively follow heart wall motion through the cardiac cycle, has already been implemented in preliminary form. Further refinements and extensions of this technique will be developed in order to improve its flexibility and ease of clinical application. Methods for quantitatively and efficiently analyzing the large amounts of data that can be produced will need to be developed in order to take full advantage of the new kinds of information on cardiac motion that this technique can make available. Effective means for displaying the results will also need to be developed in order to make them readily accessible. Validation of these results by comparison with simultaneous independent measurements of heart wall motion performed with standard invasive techniques (sonomicrometry with implanted pulse-transit piezoelectric crystals) will also be carried out in order to assess the accuracy of this new method. Finally, we will be able to use this technique to obtain much better data on normal contraction patterns in the human left ventricle than is currently available from conventional techniques.