Four Dimensional Analysis of Blood Flow Velocity in Pediatric Patients with Repaired Tetralogy of Fallot

Tetralogy of Fallot (TOF) is a congenital disease that occurs in 3.5% of children born with a malformation of the heart. The advanced imaging techniques "4D flow" of MRI allow capturing the 3D vascular anatomy and the flow velocity within the cardiac cavities and great vessels along the cardiac cycle. The objective of this study was to compare an automated (AUTO) analysis algorithm with a semi-automated (sAUTO) which was used as reference. We analyzed flow hemodynamics in 18 patients (7-17 years old, 8 women) with repaired TOF who underwent 4D flow MRI acquisition. Blood flow was retrospectively quantified using analysis planes, placed manually, in the ascending aorta (Ao), the main pulmonary artery (MPA), right (RPA) and left (LPA) pulmonary artery to quantify total flow, maximal velocity, positive and negative flow and percentage of regurgitation. Normality test of all parameters in all four vessels showed that 25% of the values were not normally distributed in the case of AUTO and 15% for sAUTO. It was found that the lowest percentage of error between the two methods was in the maximum velocity and total flow. Bland-Altman test showed good concordance and the Pearson's correlation coefficient was R=0.86 for maximal velocity and R=0.93 for the total flow. Results ware similar for maximum velocity and total flow. Therefore, we concluded that AUTO needs to improve its performance to compute hemodynamic parameters as compared with sAUTO analysis.