This project is intended to define the role of proton NMR imaging in the evaluation of ischemia heart disease. Imaging and measurement of myocardial tissue characteristics will be done using a 3.5K Gauss superconducting magnet with ECG gating. Most experiments call for the use of the spin echo imaging sequence but gated inversion recovery imaging will also be attempted and compared with the former technique in order to define the optimal technique for defining myocardial ischemia and infarction at various times after coronary occlusion. Experiments will be done with several canine models of acute myocardial ischemia; myocardial infarctions of various ages; reperfused myocardial infarctions; reversible and irreversible myocardial ischemia injury. The results will define that alterations in the NMR image of the myocardium and tissue characteristics of the myocardium associated with the various ischemia events. The NMR images and tissue characteristic will be correlated with regional myocardial perfusion (radiolabelled microspheres) and regional myocardial water content and histology. Myocardial perfusion will be assessed with NMR imaging after intravenous injection of two potential NMR contrast media (gadolinium DTPA and nitroxyl compounds). The effects of therapeutic interventions on the severity of ischemia injury will also be evaluated by NMR imaging and NMR tissue characteristic (such as magnetic relaxation factors). The results of this study should provide the scientific basis for applying and interpreting NMR imaging in ischemia heart disease in patients. It should also give insight into the advantages of this imaging technique in relation to those already widely employed in clinical medicine. Such a systematic study may avoid the enormously expensive approach of nationwide clinical trial and error as NMR imaging becomes more widely available over the next few years.
