Echocardiographic estimation of left ventricular cavity area with a newly developed automated contour tracking method

Abstract

Development of an automated contour tracking method provides detection and tracking of the endocardial boundary using the energy minimization method without tracing a region of interest. The purpose of this study was to compare the automated contour tracking method and manually drawn methods for the measurement of left ventricular cavity areas and fractional area change. Apical four-chamber view was visualized and recorded for off-line analysis in 11 patients by means of two-dimensional echocardiography. The automated contour tracking method automatically traces the endocardial border from the recorded images and calculates left ventricular cavity areas (end-diastole and end-systole) and fractional area change. In the same images selected as end-diastole and end-systole in the automated contour tracking method, left ventricular endocardial border was manually traced to calculate left ventricular cavity areas and fractional area change. Both methods were compared by linear regression analysis for the measurement of cavity areas and fractional area change. Left ventricular areas measured by the automated contour tracking method showed an excellent correlation with those by the manual method (end-diastole: r = 0.99, y = 0.83x + 2.6, standard error of the estimate = 1.5 cm 2; end-systole: r = 0.99, y = 0.96x –0.8, standard error of the estimate = 1.2 cm 2). The mean differences between the automated contour tracking and manual methods were –3.1 ± 5.1 cm 2 and –1.6 ± 2.4 cm 2 at end-diastole and end-systole, respectively. Fractional area change determined by the automated contour tracking method correlated well with that by the manual method ( r = 0.95, y = 1.17x –6.5, standard error of the estimate = 3.4%). The mean difference between the automated contour tracking and manual methods was –0.8% ± 7.1%. In conclusion, a newly developed automated contour tracking method correlates highly with the manual method for the estimation of left ventricular cavity areas and fractional area change in high-quality images. This suggests that this new technique may be useful in the automated quantitation of left ventricular function in patients with high-quality images with no dropout and no intercavity artifact or structure. (J Am Soc Echocardiogr 1997;10:822-9.)