Three-dimensional modeling of the right ventricle from two-dimensional transthoracic echocardiographic images: utility of knowledge-based reconstruction in pulmonary arterial hypertension

Purpose: Right ventricular (RV) volume and function assessments are essential in the management of pulmonary arterial hypertension (PAH) but are often difficult to perform. Three-dimensional echocardiography is limited by acoustic dropout of the RV free wall in dilated ventricles. We hypothesized that knowledge-based reconstruction, a novel method for three-dimensional modeling of RV endocardium from two-dimensional transthoracic echocardiographic (TTE) images, could provide accurate measurements of RV volumes and systolic function in PAH patients. Methods: 39 PAH patients were prospectively recruited for TTE and cardiac magnetic resonance (CMR), which was used as a reference standard and performed within 24 hr of TTE. TTE images were acquired with spatial localization equipment to allow for three-dimensional reconstruction. Images were analyzed with dedicated software to obtain RV end-diastolic and end-systolic volumes (EDV, ESV) and ejection fractions (EFs; Figure). The method of disks was used to determine CMR volumes. Results: TTE RV volumes correlated well with CMR (EDV, R=0.86; ESV, R=0.90; EF, R=0.72; Figure). On Bland-Altman analyses, volumes were slightly larger by TTE (EDV, +14.2±38.5 ml; ESV, +9.2±32.0 ml; Figure), while EFs were slightly smaller by TTE (-1.0±8.6%). For inter-observer analyses (in a subset of 27 patients), coefficients of variation were: EDV, 7.8±7.0%; ESV, 10.2±8.0%; and EF, 15.4±13.8%. For intra-observer analyses (in same 27 patients), coefficients of variation were: EDV, 7.1±5.1%; ESV, 8.3±7.0%; and EF, 10.9±9.2%. Conclusion: Knowledge-based reconstruction provides accurate, reproducible measurements of RV volumes in PAH patients. Larger studies are needed to confirm these results and to determine the practicality of this approach in clinical care.