DIAGNOSTIC METHODS NUCLEAR MAGNETIC RESONANCE Imaging by nuclear magnetic resonance in patients with chronic ischemic heart disease

Cardiac anatomy was defined by gated nuclear magnetic resonance (NMR) imaging at a magnetic field strength of 3.5 kGauss in eight normal subjects and 10 patients with chronic myocardial infarctions. Multisectional imaging was performed with the spin-echo technique and encompassed most of the left ventricle in an imaging time of 5 to 12 min. In all subjects internal cardiac structure was well delineated without the use of any type of contrast medium. The myocardial wall-blood interface was sharply defined, resulting in visualization of trabeculations, papillary muscle, and chordal structures in both ventricles. In patients with ischemic heart disease, the extent of postinfarctional wall thinning, aneurysms, and mural thrombi were depicted on NMR images. Images obtained with the second spin-echo (delay time = 56 msec) demonstrated high signal intensity in regions of the left ventricular chamber adjacent to the site of aneurysms or infarctions; this finding suggested stasis of blood in a region of akinesis or dyskinesis. The results of this study show that gated NMR is feasible as a technique for imaging the human heart and is capable of demonstrating a variety of left ventricular abnormalities associated with chronic myocardial infarction. NMR is a completely noninvasive technique for clinical imaging of the cardiovascular system. Circulation 69, No. 3, 523-531, 1984. IMAGING by nuclear magnetic resonance (NMR) has emerged in the past few years as a completely noninvasive method for visualization of internal organs. Initial success in producing high-contrast images of the brain has now also been achieved in most other parts of the body.'-' Because of the loss of NMR signal intensity by motional nuclei (hydrogen) with most proton NMR imaging techniques, flowing blood within the cardiovascular system generates little or no NMR signal; consequently, there is high natural contrast between blood and the walls of blood vessels or cardiac chambers.6'7 However, motion during imaging also complicates cardiac imaging, since signal is lost from the nuclei in the moving cardiac structures.' This factor has caused some delay in the application of NMR imaging to cardiac diseases. From the Departments of Radiology and Medicine, University of California School of Medicine, San Francisco. Supported by grant 4641/12-1 form Deutsche Forschungsgemeinschaft l.Donn (Peter Lanzer). Address for correspondence: Charles B. Higgins, M.D., Department of Radiology, University of California School of Medicine, San Francisco, CA 94143. Received Oct. 18, 1983; accepted Nov. 23, 1983. Dr. Botvinick is the recipient of an Established Investigators Award of the American Heart Association and grants from the George D. Smith Fund and the Fannie Ripple Foundtion. Dr. Lipton is the recipient of USPHS Research Career Development Award 5K04 HL00360 from the NHLBI. Vol. 69, No. 3, March 1984 Distinct advantages of NMR imaging in relation to other imaging modalities are good contrast between soft tissues and the capability for characterization of specific tissues by estimation of magnetic relaxation times.9 These advantages, along with the fact that NMR imaging of the heart requires no contrast medium, may be particularly useful in the evaluation of ischemic heart disease. Early studies measuring relaxation times of myocardial tissues samples in vitro'0 or studies imaging excised hearts"' 12 suggest that NMR imaging may be capable of discriminating necrotic from normal myocardium. The purpose of the current study was to determine whether gated NMR imaging could define the presence and site of previous myocardial infarctions and any complications of prior infarctions. The patients with ischemic heart disease were selected on the basis of distinct historical and electrocardiographic evidence of prior myocardial infarction. The NMR findings were corroborated by at least one other standard imaging modality. For comparisons, eight normal subjects were also imaged.