Cardiac magnetic resonance imaging (CMR) often shows discrepancies between right ventricular outflow tract (RVOT) flow and left ventricular outflow tract flow in patients with late-stage repaired tetralogy of Fallot (rTOF), leading to potential errors in pulmonary regurgitation fraction (PRF) assessment. This study aimed to identify the conditions under which RVOT flow can be acutely evaluated using four-dimensional (4D) flow CMR. Twenty-seven consecutive patients with rTOF underwent both two-dimensional phase-contrast (2D PC) and 4D flow CMR between 2016 and 2018, excluding those with peripheral pulmonary artery stenosis, RVOT conduit replacement, unknown surgical method, and an aortic valve regurgitation greater than 20%. Seven healthy controls also underwent only 4D Flow CMR. All healthy controls and fifteen patients with rTOF showed laminar RVOT flow, while seven patients exhibited helical, and four patients exhibited vortical RVOT flow in 4D flow CMR visualization. Flow-volume concordance between the pulmonary artery and aortic flow was significantly lower in patients with rTOF and PRF > 40% in 2D PC CMR. This concordance rate in the suprapulmonary valve was high in both the TOF and control groups, comparing at five RVOT locations in 4D flow CMR. Regarding RVOT flow regurgitation in 4D flow, the whole bulk evaluation exhibited greater variation depending on the flow type compared to the whole pixel-wise evaluation. The study confirmed the flow volume at the upper section of the pulmonary valve as the most accurate correlate of aortic flow volume. Furthermore, the 4D flow CMR using the pixel-wise method demonstrated superior accuracy compared to the traditional bulk flow method.

心脏磁共振成像 (CMR) 经常显示晚期修复法洛四联症 (rTOF) 患者的右心室流出道 (RVOT) 流量与左心室流出道流量之间的差异，导致肺动脉瓣反流分数 (PRF) 的潜在错误评估。本研究旨在确定使用四维 (4D) 血流 CMR 敏锐评估 RVOT 血流的条件。2016 年至 2018 年间，连续 27 名 rTOF 患者接受了二维相位对比 (2D PC) 和 4D 血流 CMR，不包括外周肺动脉狭窄、RVOT 导管置换、手术方法未知和主动脉瓣反流严重的患者超过20%。七名健康对照也仅接受了 4D Flow CMR。在 4D 血流 CMR 可视化中，所有健康对照和 15 名 rTOF 患者均显示层流 RVOT 流，7 名患者显示螺旋状，4 名患者显示涡旋 RVOT 流。在 2D PC CMR 中 rTOF 和 PRF > 40% 的患者中，肺动脉和主动脉血流之间的血流量一致性显着较低。与 4D 流 CMR 中的五个 RVOT 位置相比，TOF 组和对照组的肺上瓣一致性率都很高。关于 4D 血流中的 RVOT 血流反流，与整个像素级评估相比，整个整体评估根据血流类型表现出更大的变化。该研究证实肺动脉瓣上部的流量是主动脉流量最准确的相关性。此外，与传统的整体流方法相比，使用逐像素方法的 4D 流 CMR 表现出更高的精度。