EVALUATION OF MITRAL-STENOSIS WITH VELOCITY-ENCODED CINE-MAGNETIC RESONANCE IMAGING

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Abstract

Velocity-encoded cine-magnetic resonance imaging (VEC-MRI) is a new method for quantitation of blood flow with the potential to measure high-velocity jets across stenotic valves. The objective of this study was to evaluate the ability of VEC-MRI to measure transmitral velocity in patients with mitral stenosis. Sixteen patients with known mitral stenosis were studied. A 1.5 Tesla superconducting magnet was used to obtain velocity-encoded images in the left ventricular short-axis plane. Images were obtained throughout the cardiac cycle at 3 consecutive slices beginning proximal to the mitral coaptation point. To determine the optimal slice thickness for MRI imaging, both 10 mm and 5 mm thicknesses were used. Echocardiography including continuous-wave Doppler was performed on every patient within 2 hours of MRI imaging. Peak velocity was determined for both VEC-MRI and Doppler-echo images. Two observers independently measured the VEC-MRI mitral inflow velocities. Of the 16 patients, imaged data were incomplete in only 1 study, and all images were adequate for analysis. Strong correlations were found for measurements of mitral valve gradient for both 10 mm (peak r = 0.89, mean r = 0.84) and 5 mm (peak r = 0.82, mean r = 0.95) slice thicknesses. Measurements of peak velocity with VEC-MRI (10 mm) agreed well with Doppler: mean 1.46 m/s, mean of differences (Doppler MRI) 0.38 m/s, standard deviation of differences 0.2 m/s. These findings suggest that VEC-MRI can noninvasively determine the severity of mitral stenosis.

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