ABSTRACT
In the early days of cardiovascular magnetic resonance (CMR) imaging, the methodology was appropriately called nuclear magnetic resonance (NMR) imaging since there are other types of magnetic resonance applied to spectroscopic approaches including electron spin resonance and Mo¨ssbauer magnetic resonance. However, in the late 1980s the ‘‘nuclear’’ in medical NMR was dropped and the name changed to the non-specific name magnetic resonance imaging so as not to confuse it with nuclear medicine and so that the public would not think the methodology was in any way associated with ionizing radiation. The first ‘‘NMR’’ examinations of the heart were performed in the early 1980s. Goldman et al. evaluated myocardial perfusion in excised canine models of coronary artery occlusion using the paramagnetic contrast agent manganese chloride (MnCl2) administered prior to sacrifice (1). Due to the high toxicity of the intravenously administered manganese compound, it could not be used as a clinical agent. Shortly after the administration of the agent the dogs died and hearts excised and imaged in an 5-inch bore, 1.4 T superconducting magnet. Studies were
performed in vivo in 1984 with the addition of gating; however, the images were low resolution acquired in a 0.1 T system in Aberdeen, Scotland (2). Many technical problems were evident, including relatively poor image quality resembling radionuclide studies and long acquisition times of greater than 10minutes. Cardiac MR imaging represented a challenge for physicians and manufacturers. The assessment of morphology and function was essential initially. The challenge was to identify the appropriate pulse sequence to generate diagnostically adequate resolution and contrast and to improve upon two-dimensional (2D) echocardiography and relatively low-resolution radionuclide imaging. Other applications of CMR were clear from previous work including assessment of myocardial perfusion (3). The application of CMR for detection of diseases of the aorta and peripheral arterial vasculature suggested the use of CMR for non-invasive coronary angiography (4).
