Value of echocardiography using knowledge-based reconstruction in determining right ventricular volumes in pulmonary sarcoidosis: comparison with cardiac magnetic resonance imaging

Right ventricular (RV) dysfunction in sarcoidosis is associated with adverse outcomes. Assessment of RV function by conventional transthoracic echocardiography (TTE) is challenging due to the complex RV geometry. Knowledge-based reconstruction (KBR) combines TTE measurements with three-dimensional coordinates to determine RV volumes. The aim of this study was to investigate the accuracy of TTE-KBR compared to the gold standard cardiac magnetic resonance imaging (CMR) in determining RV dimensions in pulmonary sarcoidosis. Pulmonary sarcoidosis patients prospectively received same-day TTE and TTE-KBR. If performed, CMR within 90 days after TTE-KBR was used as reference standard. Outcome parameters included RV end-diastolic volume (RVEDV), end-systolic volume (RVESV), stroke volume (RVSV) and ejection fraction (RVEF). 281 patients underwent same day TTE and TTE-KBR. In total, 122 patients received a CMR within 90 days of TTE and were included. TTE-KBR measured RVEDV and RVESV showed strong correlation with CMR measurements (R = 0.73, R = 0.76), while RVSV and RVEF correlated weakly (R = 0.46, R = 0.46). Bland-Altman analyses (mean bias ± 95% limits of agreement), showed good agreement for RVEDV (ΔRVEDVKBR-CMR, 5.67 ± 55.4 mL), while RVESV, RVSV and RVEF showed poor agreement (ΔRVESVKBR-CMR, 21.6 ± 34.1 mL; ΔRVSVKBR-CMR, - 16.1 ± 42.9 mL; ΔRVEFKBR-CMR, - 12.9 ± 16.4%). The image quality and time between CMR and TTE-KBR showed no impact on intermodality differences and there was no sign of a possible learning curve. TTE-KBR is convenient and shows good agreement with CMR for RVEDV. However, there is poor agreement for RVESV, RVSV and RVEF. The use of TTE-KBR does not seem to provide additional value in the determination of RV dimensions in pulmonary sarcoidosis patients.