Four-dimensional flow MRI quantification of pulmonary regurgitation in patients with repaired tetralogy of Fallot: a study on reproducibility and consistency / 中华放射学杂志

ABSTRACT

Objective@#To investigate the feasibility and consistency of four-dimensional flow (4D flow) quantification of pulmonary regurgitation in patients with repaired Tetralogy of Fallot (ToF) by comparing with conventional two-dimensional flow (2D flow) and echocardiography.@*Methods@#Both the 4D flow and 2D flow imaging were acquired with repaired ToF (a total of 21 patients) consecutively on 3.0 T MR scanner from May 2018 to August 2018. Pulmonary flow and regurgitant fraction were measured by a commercial post processing software Circle CVI42. All patients underwent echocardiography within one week after or before MR examination. The inter/intra-observer variability by 2D/4D f1ow and agreement between the two methods were investigated by interclass correlation coefficients (ICC) and Bland-Altman analyses. The agreement between MR and echocardiography were analyzed by weighted Kappa coefficient. The correlation between pulmonary regurgitation and cardiac function was also investigated by Pearson analysis.@*Results@#All patients were included and completed the examinations successfully. Both inter-observer and intra-observer agreement by 4D flow for total forward volume (ICC=0.993, 0.996, respectively, P<0.001), total backward volume (ICC=0.994, 0.997, respectively, P<0.001) and regurgitant fraction (ICC=0.968, 0.985, respectively, P<0.001) were good. The total forward volume, total backward volume and regurgitant fraction measured by 2D flow and 4D flow reached a good agreement (ICC=0.954, 0.913,0.721,respectively,P<0.001). The consistency was good for severity of regurgitation measured by 2D flow (weighted Kappa=0.897, P<0.001) and 4D flow (weighted Kappa=0.710, P=0.001) compared with echocardiography. Significant correlation was found among right ventricular cardiac index(r=0.600, P<0.05), right ventricular end-diastolic volume index(r=0.788, P<0.05), right ventricular end-systolic volume index(r=0.683, P<0.05) and left ventricular end-diastolic volume index(r=0.578, P<0.05), left ventricular end-systolic volume index(r=0.687, P<0.05) with regurgitant fraction measured by 2D flow. Regurgitant fraction measured by 4D flow had a significant correlation with right ventricular cardiac index(r=0.606, P<0.05), right ventricular end-diastolic volume index(r=0.685,P<0.05), right ventricular end-systolic volume index(r=0.534, P<0.05) and left ventricular end-diastolic volume index(r=0.459, P<0.05), left ventricular mass index(r=0.633, P<0.05).@*Conclusion@#4D flow MRI provides highly reproducible measurements of pulmonary flow on morphology and haemodynamics in patients with repaired ToF compared with 2D flow MRI and echocardiography.