[Imaging of the heart using nuclear magnetic resonance tomography. I: Tomography]

Abstract

Magnetic resonance (MR) is a new concept in the diagnostics of the cardiovascular system. The basic principle of MR is nuclear magnetism. MR tomography is based on induction and spatial encoding of a nuclear magnetic resonance signal. Due to the high tissue concentration and MR sensitivity, medical MR imaging chiefly uses protons of water, 1H. MR tomography of protons presents highly contrasted images of soft tissue organs with spatial resolution in millimeters. Parametric analysis of the MR signal enables quantitative assessments of physico-chemical tissue properties, blood flow and perfusion. The method is noninvasive and without serious biological side effects. Ionising radiation or traditional contrast agents are not utilized. Using conventional ECG synchronized MR tomography the cardiac and great vessels anatomy are superbly resolved, exceptions being the resolution of coronary vasculature and cardiac valve apparatus. The excellent spatial resolution and flexible spatial image orientation are important advantages of quantitative assessment of cardiac function by MR imaging. Preliminary studies demonstrated clinical utility of tomographic assessments of T1 and T2 relaxation parameters as well as phase angle analysis for definition of myocardial ischemia, blood flow rates and wall motion dynamics. The first comparative studies between imaging modalities in diagnostics of specific cardiac disorders point to a superior anatomic resolution of the heart and vascular morphology by MR tomography. The utilization of MR tomography in cardiovascular medicine is new and it would be premature to assign a definite value to this costly technique in clinical evaluations of patients with heart disease. However, there is unequivocal evidence that MR technology will play a decisive role in cardiology in the future, and MR imaging already represents significant progress in the evaluation of patients with cardiac disease.