Semiautomatic Detection of Left Ventricular Contours in Contrast-enhanced Echocardiographic Images: Comparison with Magnetic Resonance Imaging

The aim of this study was to evaluate the accuracy of a semiautomatic contour detection method for left ventricular (LV) volume calculation in contrast-enhanced echocardiographic images. In 26 patients, LV volumes were automatically measured by magnetic resonance imaging and second harmonic echocardiography after intravenous Levovist administration. LV cavity edges were manually drawn and semiautomatically outlined using the active contour algorithm, improved by a nonlinear anisotropic filter; LV volumes were calculated by the modified Simpson's rule. Manual and semiautomatic analysis of echocardiographic images lasted 45 6 and 20 8 seconds, respectively. Contrast echocardiography volumes were smaller than those by magnetic resonance imaging (mean difference: 16 mL for manual and 18 mL for automatic analysis). LV volumes by echocardiography closely related with those by magnetic resonance imaging using both manual (r 0.955) and semiautomatic (r 0.945) analysis; the correlation was closer for end-systolic than for enddiastolic volumes. In conclusion, this method provides a fast measure of LV volumes in contrastenhanced images while reducing operator dependency.