Semi-automatic segmentation and tracking of the left ventricle in healthy horses and horses with severe aortic valve regurgitation using an optical flow-based B-spline explicit active trackin of surfaces (ofBEATS) method

Abstract

In human medicine, optical flow-based B-spline explicit active tracking of surfaces (ofBEATS) is a semi-automatic segmentation and tracking technique for determination of left ventricular diameter, length, area and curvature and is used for volumetric assessment. The objective was to evaluate the use of ofBEATS in normal horses and horses with severe aortic valve regurgitation. ofBEATS was applied on the left ventricle in a four chamber view image of 15 normal horses and 12 horses with severe aortic valve regurgitation. The end-diastolic mean ± standard deviation length, basal diameter (20% of total length from mitral valve annulus), apical diameter (20% of the total length from apex), total area and apical curvature in the normal horses and horses with severe aortic valve regurgitation were 17.6±1.9 cm, 12.5±1.3 cm, 7.1±0.8 cm, 170.3±28.5 cm², 25.5±3.4 cm-1 and 19.9±2.0 cm, 15.0±1.9 cm, 9.3±2.1 cm, 237.8±53.4 cm², 19.8±3.7 cm-1, respectively. The mean length, basal diameter, apical diameter, total area and apical curvature at end-systole in the normal horses and horses with severe aortic valve regurgitation were 12.6±1.5 cm, 9.7±1.4 cm, 3.1±1.0 cm, 82.9±14.8 cm², 85.0±98.8 cm-1 and 14.8±3.1 cm, 11.8±2.3 cm, 5.1±2.8 cm, 131.1±57.7 cm², 41.4±18.5 cm-1, respectively. All measurements, except the end-systolic curvature value, were significantly different in the horses with severe aortic valve regurgitation. ofBEATS can be used in equine echocardiography. Besides differences in left ventricular size and area it also allowed objective quantification of left ventricular apical curvature which was significantly different in horses with severe aortic valve regurgitation