Costello Benedict T, Qadri Mateen, Price Bradley, Papapostolou Stavroula, Thompson Mark, Hare James L, La Gerche Andre, Rudman Murray, Taylor Andrew J
Department of Cardiovascular Medicine, Alfred Hospital, Melbourne, VIC, Australia.
Baker Heart and Diabetes Institute, Melbourne, Australia.
Int J Cardiovasc Imaging. 2018 Dec;34(12):1927-1935. doi: 10.1007/s10554-018-1407-0. Epub 2018 Jun 27.
4D flow cardiac magnetic resonance (CMR) imaging allows visualisation of blood flow in the cardiac chambers and great vessels. Post processing of the flow data allows determination of the residence time distribution (RTD), a novel means of assessing ventricular function, potentially providing additional information beyond ejection fraction. We evaluated the RTD measurement of efficiency of left and right ventricular (LV and RV) blood flow. 16 volunteers and 16 patients with systolic dysfunction (LVEF < 50%) underwent CMR studies including 4D flow. The RTDs were created computationally by seeding virtual 'particles' at the inlet plane in customised post-processing software, moving these particles with the measured blood velocity, recording and counting how many exited per unit of time. The efficiency of ventricular flow was determined from the RTDs based on the time constant (RTDc = - 1/B) of the exponential decay. The RTDc was compared to ejection fraction, T1 mapping and global longitudinal strain (GLS). There was a significant difference between groups in LV RTDc (healthy volunteers 1.2 ± 0.13 vs systolic dysfunction 2.2 ± 0.80, p < 0.001, C-statistic = 1.0) and RV RTDc (1.5 ± 0.15 vs 2.0 ± 0.57, p = 0.013, C-statistic = 0.799). The LV RTDc correlated significantly with LVEF (R = - 0.84, P < 0.001) and the RV RTDc had significant correlation with RVEF (R = - 0.402, p = 0.008). The correlation between LV RTDc and LVEF was similar to GLS and LVEF (0.926, p < 0.001). The ventricular residence time correlates with ejection fraction and can distinguish normal from abnormal systolic function. Further assessment of this method of assessment of chamber function is warranted.
四维血流心脏磁共振（CMR）成像可实现对心腔和大血管内血流的可视化。对血流数据进行后处理可确定停留时间分布（RTD），这是一种评估心室功能的新方法，可能提供除射血分数之外的额外信息。我们评估了左、右心室（LV和RV）血流效率的RTD测量。16名志愿者和16名收缩功能不全（左心室射血分数<50%）患者接受了包括四维血流的CMR研究。通过在定制的后处理软件中在入口平面播种虚拟“粒子”，根据测量的血流速度移动这些粒子，记录并计算每单位时间有多少粒子流出，从而通过计算创建RTD。基于指数衰减的时间常数（RTDc = -1/B）从RTD确定心室血流效率。将RTDc与射血分数、T1映射和整体纵向应变（GLS）进行比较。LV RTDc在组间存在显著差异（健康志愿者为1.2±0.13，收缩功能不全患者为2.2±0.80，p<0.001，C统计量=1.0），RV RTDc也存在显著差异（1.5±0.15 vs 2.0±0.57，p = 0.013，C统计量=0.799）。LV RTDc与左心室射血分数显著相关（R = -0.84，P<0.001），RV RTDc与右心室射血分数显著相关（R = -0.402，p = 0.008）。LV RTDc与左心室射血分数之间的相关性与GLS和左心室射血分数之间的相关性相似（0.926，p<0.001）。心室停留时间与射血分数相关，可区分正常与异常收缩功能。有必要对这种评估心腔功能的方法进行进一步评估。
