Three-dimensional echocardiography in a dynamic heart phantom: comparison of five different methods to measure...

Several methods of analysis are available for quantification of left ventricular volumes and ejection fraction using three-dimensional (3D) echocardiography. This study compared the accuracy and reproducibility of five methods of analysis in a novel, irregularly shaped dynamic heart phantom with excellent image quality. Five 3D datasets were acquired on a Philips IE33 platform using an X5-1 3D transducer. Each dataset was analysed by five different methods using the Philips QLab v8.1 software: Methods A1, A2 and A3, semi-automated contour detection with varying degrees of user correction; Method B, Simpson's biplane method using optimally aligned four- and two-chamber views and Method C, method of discs, manually delineated in reconstructed short-axis views. Time-volume curves were generated for each method and compared with the true volumes measured throughout systole in the phantom heart. A second observer repeated measurements by each method in a single 3D dataset. Method A1 (uncorrected semi-automated contouring) produced the most consistent time-volume curves, although end-diastolic and end-systolic volumes varied between datasets. Any manual correction of contours (Methods A2, A3 and B) resulted in significant variation in the time-volume curves, with less consistent endocardial tracking. Method C was not only the most accurate and reproducible method, but also the most time-consuming one. Different methods of 3D volume quantification vary significantly in accuracy and reproducibility using an irregular phantom heart model. Although contouring may appear optimal in long-axis views, this may not be replicated circumferentially, and the resulting measures appeared to be less robust following the manual correction of semi-automated contours.