Accuracy of pulmonary venous flow quantification by 2D phase contrast cardiac magnetic resonance

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Determination of pulmonary venous flow by cardiac magnetic resonance (CMR) is frequently required in patients with complex congenital heart disease (CHD) lesions. Although new advanced imaging techniques like 4D flow are increasingly available, standard 2D phase contrast (2DPC) sequences remain the most frequently used method for quantification of flow. However, little is known on the accuracy of 2DPC flow measurements in the pulmonary veins. Purpose This study therefore aims to investigate the accuracy of pulmonary venous flow quantification by 2DPC. Methods Patients with CHD underwent a CMR on a 1.5T scanner. 2DPC flow sequences (typical temporal resolution 35–50ms, inplane spatial resolution 1.3–1.8 mm2, VENC 80–100) were acquired in the ascending aorta (AA), main, right and left pulmonary arteries (MPA, RPA, LPA), as well as left (LPV) and right (RPV) pulmonary veins. Pulmonary venous flow was compared to pulmonary arterial flow in all patients and to aortic flow in patients without left to right (L-R) shunt using Bland-Altman plots and Pearson’s correlations. Results Twenty CHD patients (age 27±3, range 7; 53 years, 7 women, tetralogy of Fallot N=7, Ross operation N=1; Fontan N=4, transposition of great arteries N=2, atrial septal defect N=2, Turner syndrome 1, Ebstein N=1, valvulopathies N=2) were included. Table 1 shows absolute flow values of the different vessels. Bland-Altman analyses and correlations (Table 2) showed a good agreement of total pulmonary venous (PV) to flow in the ascending aorta (group without shunt) and the sum of flow of both branch pulmonary arteries. However, agreement of total PV with MPA flow as well as of LPV and RPV with the respective branch pulmonary artery flow was reduced. Conclusions Total PV flow determined by 2DPC shows a good agreement with flow in the ascending aorta and the sum of the branch pulmonary arteries. Flow turbulences due to the pathologies of the right ventricular outflow tract probably contribute to the reduced agreement of total PV and MPA flow. However, the reduced agreement of the flow in left/right pulmonary veins and their respective branch pulmonary arteries underlines the need for newer advanced flow quantification techniques to improve accuracy of pulmonary venous flow measurements.