Abstract：
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.
摘要：
心脏磁共振成像（CMR）通常显示晚期法洛四联症（rTOF）患者右心室流出道（RVOT）流量与左心室流出道流量之间的差异，导致肺返流分数（PRF）评估的潜在错误。本研究旨在确定可以使用四维（4D）流CMR对RVOT流进行严格评估的条件。在2016年至2018年期间，有27例连续的rTOF患者接受了二维相位对比（2DPC）和4D流量CMR，不包括那些周围性肺动脉狭窄的患者。RVOT导管更换，未知的手术方法，主动脉瓣反流超过20%。七个健康对照也仅进行了4DFlowCMR。所有健康对照和15例rTOF患者均表现为层状RVOT血流，虽然七名患者表现出螺旋状，4例患者在4D流量CMR可视化中表现出涡旋RVOT流量。在2DPCCMR中，rTOF和PRF>40％的患者肺动脉和主动脉血流之间的流量-体积一致性显着降低。肺上瓣膜的一致率在TOF组和对照组中均较高，在4D流量CMR中的五个RVOT位置进行比较。关于4D流中的RVOT流返流，与整个像素级评估相比，整个整体评估根据流动类型表现出更大的变化。该研究证实了肺动脉瓣上段的流量是与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，使用像素级方法的4D流CMR显示出更高的准确性。
