Showing papers on "Cardiac magnetic resonance imaging published in 1997"

Analysis of cardiac function from MR images

Abstract: Recent research and development in cardiac magnetic resonance imaging (MRI) has shown that a single exam, performed entirely in an MR scanner, might well replace the current sequence of tests for coronary disease. Though an MR scanner is expensive, the ability to consolidate diagnostic tests into a single session would significantly reduce costs and increase convenience for the patient. MRI might also provide the physician with diagnostic information on myocardial function that is not available from the standard battery of tests. In this article, we concentrate on one aspect of a cardiac MRI exam that provides previously unavailable information: assessment of myocardial contraction.

Cardiac magnetic resonance imaging findings in patients with right ventricular outflow tract premature contractions.

Abstract: Aims To assess prospectively the value of cardiac magnetic resonance imaging in patients with apparently idiopathic premature contractions arising from the right ventricular outflow tract. Methods We compared magnetic resonance imaging scans in 19 patients (13 males and six females, mean age 44 years) with frequent (>100 per hour), monomorphic (left bundle branch block and inferior axis morphology) extrasystoles, and in 10 volunteers (four males and six females, mean age 36·7 years) without structural heart disease. Magnetic resonance imaging studies (1 or 1·5 Tesla) included spinecho and gradient-echo sequences in the standard planes. The presence of structural and dynamic abnormalities of the right and left ventricles, such as reduced wall thickness, systolic bulging, and decreased systolic thickening, were evaluated. In addition, end-diastolic diameters of the right ventricular outflow tract were measured in the transverse plane. Results The dimensions of the right ventricular outflow tract were wider in patients with extrasystoles compared to the control group. Mean anteroposterior and transverse diameters were 39·6±4·6 mm vs 29·9±4·8 mm ( P <0·01) and 27·5±3·8 mm vs 20·5±2·5 mm ( P <0·01), respectively. Wall motion and morphological abnormalities were present in 16/19 (84%) patients, and were confined to the anterolateral wall in 15/16 cases. All normal subjects had normal magnetic resonance imaging findings ( P =0·008). Conclusions Cardiac magnetic resonance imaging revealed that in patients with idiopathic right ventricular outflow tract premature contractions there was a higher rate of morphological and functional abnormalities of the right ventricular outflow tract than in the normal subjects. Large studies and long follow-up are needed to confirm whether these findings could help identify a localized form of arrhythmogenic cardiomyopathy, and its clinical significance.

Techniques for High-speed Cardiac Magnetic Resonance Imaging in Rats and Rabbits

Abstract: Progress in research on hypertension, heart failure, aging, post-infarct remodeling, and the molecular basis of cardiovascular diseases in general has been greatly facilitated in recent years by the development of specialized small-mammal models by selective breeding and/or genetic alteration Routine noninvasive evaluation of cardiac function and perfusion in these animals models, however, is difficult using existing methods In principle, MRI can be used for this purpose, but in practice this is difficult because of problems related to RF coils, cardiac gating, and imaging pulse sequences In this article, solutions to these problems are described that have allowed us to use MRI to routinely image the hearts of rats and rabbits Specifically described are four RF coils, cardiac gating schemes, and an imaging pulse sequence specially designed for cardiac imaging in these animals on a 47 T Omega chemical-shift imaging (CSI) spectrometer These techniques can be used to obtain, within 2 min, eight double-oblique short-axis images of the rat at different cardiac phases with 200 × 400 μm in-plane resolution and a slice thickness of 2 mm Moreover, myocardial tissue tagging can be performed with tag thicknesses and separations comparable to those used routinely in humans The technical information is presented in sufficient detail to allow researchers at other sites to reproduce the results This information should facilitate the use of MRI for the noninvasive examination of cardiac function and perfusion, which can be combined with other established techniques for the study of cardiovascular disease in specialized animal models

Noninvasive Measurement of Cardiac Strain with MRI

Abstract: The motion sensitivity of cardiac magnetic resonance imaging (MRI) can be exploited to measure the motion patterns within the heart wall and thus to noninvasively calculate the intramyocardial strain. The resulting large data sets pose a challenge for visualization, but offer the potential of a greatly improved picture of cardiac dynamics. This may have both basic research and clinical applications.

The Diagnostic Approach to Single Ventricle

Abstract: Hearts with a single ventricle frequently have complex anomalies, such as atrial isomerism, involving the systemic and pulmonary veins. From the clinical and surgical points of view, the morphology and size of the pulmonary arteries and atrioventricular (AV) valve competency are more important than other lesions in these anomalies. If the AV valve is undivided, like the endocardial cushion valve, there may be significant regurgitation; if one of the divided valves is atretic or has no connection, however, the other valve may be more competent or show mild regurgitation. This is important for the long-term prognosis of those patients who undergo the modified Fontan procedure or total cavopulmonary connection surgery. A single diagnostic tool is usually not satisfactory for the study of single ventricles. Echocardiography, angiocardiography, and sometimes cardiac magnetic resonance imaging are needed, complementing each other, for correct diagnosis and assessment of the complex cardiac lesions.