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Cardiac function by magnetic resonance imaging
H J Deutsch1, J Smolorz, U Sechtem
1Medical Clinic III, University of Cologne, FRG.
Insights
Gated magnetic resonance imaging (MRI) accurately assesses left ventricular ejection fraction, correlating well with traditional methods. This cardiac MRI technique offers valuable insights into cardiac function and regional wall motion.
Area of Science:
- Cardiovascular Imaging
- Medical Physics
- Diagnostic Radiology
Background:
- Gated magnetic resonance imaging (MRI) provides high-resolution cardiac visualization.
- Assessing cardiac physiology requires capturing both systolic and diastolic phases.
Purpose of the Study:
- To evaluate the accuracy of MRI in determining left ventricular ejection fraction.
- To compare MRI findings with established angiocardiography and radionuclide ventriculography.
Main Methods:
- Left ventricular ejection fraction was calculated using the area-length formula from oblique long axis MRI views in 50 patients.
- Electronic gradient angulation was employed for acquiring angulated views.
- Comparison data included monoplane angiocardiography and radionuclide ventriculography.
Main Results:
- MRI ejection fraction showed a strong correlation with angiocardiography (r=0.90).
- MRI also demonstrated acceptable correlation with radionuclide ventriculography (r=0.79).
- MRI provides data on regional wall motion in addition to global function.
Conclusions:
- Gated cardiac MRI is a reliable method for assessing left ventricular ejection fraction.
- Emerging MRI techniques with faster imaging show promise for detailed cardiac cycle analysis.
- MRI offers combined anatomical and functional information for cardiovascular assessment.
Abstract:
Gated magnetic resonance imaging of the heart displays cardiac structures with excellent resolution. This ability should be useful for assessment of cardiac physiology where acquisition of systolic and diastolic images is required. In this study, left ventricular ejection fraction was determined in 50 patients from oblique long axis views of the left ventricle using the area length formula. Angulated views were obtained by electronic gradient angulation. For comparison, all patients had monoplane angiocardiography in the RAO position. Forty-five patients were also studied by radionuclide ventriculography. Ejection fractions determined by MRI and angiocardiography were closely correlated (r = 0.90). Correlation between MRI and radionuclide ventriculography was also acceptable (r = 0.79). In addition to global left ventricular function, MR images provide information about regional wall motion. In order to acquire a three-dimensional set of images at various phases of the cardiac cycle, shorter imaging times are mandatory. A new imaging technique with potential for functional studies uses low flip angles, short repetition times and gradient refocused echoes. Up to 40 images can be obtained within one cardiac cycle. When displayed in a looped fashion, visual assessment of cardiac motion, intracardiac blood flow, and systolic wall thickening is possible. Potential advantages of functional studies by MRI are the concomitant acquisition of anatomical information and the three dimensional frame of reference.