Direct measurement of aortic regurgitation with phase-contrast magnetic resonance is inaccurate: proposal of an alternative method of quantification
Direct measurement of aortic regurgitation with phase-contrast magnetic resonance is inaccurate: proposal of an alternative method of quantification
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DOI：
10.1007/s00247-014-3017-x
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发表时间：
2014-11-01
影响因子：
2.3
通讯作者：
Yoo, Shi-Joon
中科院分区：
文献类型：
--
作者：
Iwamoto, Yoichi;Inage, Akio;Yoo, Shi-Joon
相衬磁共振（MR）已广泛应用于主动脉反流的定量诊断。然而，在获取血流数据的地点和方式方面存在显著的实践差异。比较右肺动脉升主动脉水平（1级）、舒张末期主动脉瓣铰点（2级）和收缩期末期主动脉瓣铰点（3级）三个水平主动脉瓣返流定量的准确性。我们对43例主动脉反流患儿进行了心血管MR检查。通过相对比MR，我们测量了三个水平的收缩前向、舒张逆行和净前向流量指数。在每个水平上进行以下比较：(1)收缩期前血流容量指数（FFVI）与电影心室容积法测量的左心室心脏指数（LVCI）；(2)逆行血流容量指数（RFVI）与估计主动脉反流容量指数（LVCI减去肺血流指数[QPI]）；(3)净前流量指数（NFVI）与肺血流指数。除1级和3级逆行流量指数外，3个水平的正向流量指数、逆行流量指数和净正向流量指数均存在显著差异。前向血流容量指数与左心室心脏指数在三个水平上均有良好的相关性，其中第2水平的测量结果相关性最好。与前向血流容积指数相比，逆行血流容积指数与主动脉反流容积指数的相关性较低，数据分布广泛，预测区间较大。在不同水平的主动脉瓣和升主动脉上观察到收缩前、舒张逆行和净前流量的巨大变化。直接测量主动脉反流体积和分数是不准确的，应放弃。相反，建议根据更可靠的数据计算主动脉反流量。我们推荐从舒张末期主动脉瓣铰链处测量的收缩前流中减去肺血流量，作为计算主动脉反流容量的更准确和一致的方法。
Phase-contrast magnetic resonance (MR) has been widely used for quantification of aortic regurgitation. However there is significant practice variability regarding where and how the blood flow data are acquired.To compare the accuracy of flow quantification of aortic regurgitation at three levels: the ascending aorta at the level of the right pulmonary artery (level 1), the aortic valve hinge points at end-diastole (level 2) and the aortic valve hinge points at end-systole (level 3).We performed cardiovascular MR in 43 children with aortic regurgitation. By using phase-contrast MR, we measured the systolic forward, diastolic retrograde and net forward flow volume indices at three levels. At each level, the following comparisons were made: (1) systolic forward flow volume index (FFVI) versus left ventricular cardiac index (LVCI) measured by cine ventricular volumetry; (2) retrograde flow volume index (RFVI) versus estimated aortic regurgitation volume index (which equals LVCI minus pulmonary blood flow index [QPI]); (3) net forward flow volume index (NFVI) versus pulmonary blood flow index.The forward flow volume index, retrograde flow volume index and net forward flow volume index measured at each of the three levels were significantly different except for the retrograde flow volume index measured at levels 1 and 3. There were good correlations between the forward flow volume index and the left ventricular cardiac index at all three levels, with measurement at level 2 showing the best correlation. Compared to the forward flow volume indices, the retrograde flow volume index had a lower correlation with the estimated aortic regurgitation volume indices and had widely dispersed data with larger prediction intervals.Large variations in systolic forward, diastolic retrograde and net forward flow volumes were observed at different levels of the aortic valve and ascending aorta. Direct measurement of aortic regurgitation volume and fraction is inaccurate and should be abandoned. Instead, calculation of the aortic regurgitation volume from more reliable data is advised. We recommend subtracting pulmonary blood flow from systolic forward flow measured at the aortic valve hinge points at end-diastole as a more accurate and consistent method for calculating the volume of aortic regurgitation.