Assessment Of Dilated Right Ventricular Volume By Two Dimensional And Real-Time Three-Dimensional Echocardiography—Compared With Cardiac Magnetic Resonance Imaging

Object 1. To evaluate the accuracy of real-time three-dimensional echocardiography(RT-3DE) for calculation of dilated right ventricular(RV) volume.2. To explore the method and accuracy of two-dimensional echocardiography(2-DE) for measuring dilated RV volume.Methods A total of 32 patients with dilated RV were enrolled by 2-DE, RT-3DE and cardiac magnetic resonance imaging(c MRI) within 24 hours. All the exams including 2-DE and RT-3DE were performed by skilled sonographer who was blind and got the data from the average of five times of measurements(right ventricular longitudinal dimension, diameter at base and area at modified apical 4-chamber, the largest length of tricuspid valve to pulmonary valve at parasternal short-axis of basal RV) in at list five cardiac cycles. Both c MRI and RT-3DE images should be analyzed by post processing software, and be delineated the endocardia blindly twice or more to calculate the volume and then adopted the average. Two methods of 2DE were included to measure the expanded RV volume, one was the biplane area-length method, which was defined as V=2/3×Y×A(Y is for the distance from pulmonary valve to tricuspid valve, and A stands for the RV area from apical four-chamber view based on RV), and the other one was the half ellipsoid method, which was defined as V=π×X×Y×Z/8(X stands for the basement diameter of right ventricle, Y is for the max distance from intersection of anterior tricuspid leaflet and right ventricular free wall to RVOT, that is the distance from tricuspid valve to pulmonary valve, and Z is the long diameter of right ventricle, meaning the distance from right ventricular apex to the middle of tricuspid valve). The dilated right ventricular end-diastolic and end-systolic volume(RVEDV and RVESV) were calculated respectively. Then the results of 2-DE and RT-3DE were separately compared to c MRI. All the results were indicated by mean±standard deviation;2DE and RT-3DE were compared with c MRI by paired t-test, linear correlation andBland-Altman consistency checking.Results Compared with cMRI, the biplane area-length method overestimated RVEDV and underestimated RVESV, but there’s no statistical significance(p>0.05, both), and they were correlated well with c MRI(r=0.728,0.643,each, and p<0.001), while when checked with Bland-Altman analysis, the D-values seemed high and couldn’t be accepted by clinical. Compared to c MRI, the half ellipsoid method underestimated RVEDV and RVESV, with statistical significance(p<0.001, both), the RVEDV was correlated well with c MRI(r=0.728,p<0.001), while the RVESV was not. RT-3DEV underestimated RVEDV and RVESV, while thers’ s no significantly statistical difference(p>0.05, both), the correlations between RT-3DE and c MRI were the best(r=0.921,0.803, each, and p<0.001). RT-3DE, which correlated highly with c MRI were analyzed with the c MRI results by Bland-Altman analysis. The results showed there is only 1/32 of the D-values out of the limits. Within the limits, the max difference of RVEDV between RT-3DE and c MRI was 20.9ml, and the average of the two was 182.3ml, showing it’s acceptable, and similarly the RVESV is accepted, too.Conclusion Real-time three-dimensional echocardiography is a tool could accurately measure right ventricular volume and substitute for c MRI in patients with dilated right heart.