Huh Hyungkyu, Lee Jeesoo, Kinno Menhel, Markl Michael, Thomas James D, Barker Alex J
Medical Device Development Center, Daegu-Gyeongbuk Medical Innovation Foundation, Daegu, South Korea.
Department of Radiology, Northwestern University, Feinberg School of Medicine, 737 N. Michigan Avenue, Suite 1600, Chicago, IL, 60611, USA.
Int J Cardiovasc Imaging. 2022 Aug;38(8):1815-1823. doi: 10.1007/s10554-022-02553-8. Epub 2022 Feb 21.
This study aims to systematically verify if the simplified geometry and flow profile of the left ventricular outflow tract (LVOT) assumed in 2D echocardiography is appropriate while examining the utility of 4D flow MRI to assess valvular disease. This prospective study obtained same-day Doppler echocardiography and 4D flow MRI in 37 healthy volunteers (age: 51.9 ± 18.2, 20 females) and 7 aortic stenosis (AS) patients (age: 64.2 ± 9.6, 1 female). Two critical assumptions made in echocardiography for aortic valve area assessment were examined, i.e. the assumption of (1) a circular LVOT shape and (2) a flat velocity profile through the LVOT. 3D velocity and shape information obtained with 4D flow MRI was used as comparison. It was found that the LVOT area was lower (by 26.5% and 24.5%) and the velocity time integral (VTI) was higher (by 28.5% and 30.2%) with echo in the healthy and AS group, respectively. These competing errors largely cancelled out when examining individual and cohort averaged LVOT stroke volume. The LVOT area, VTI and stroke volume measured by echo and 4D flow MRI were 3.6 ± 0.7 vs. 4.9 ± 1.0 cm (p < 0.001), 21.2 ± 3.0 vs 15.2 ± 2.8 cm (p < 0.001), and 75.6 ± 15.6 vs 72.8 ± 14.1 ml (p = 0.3376), respectively. In the ensemble average of LVOT area and VTI, under- and over-estimation seem to compensate each other to result in a 'realistic' stroke volume. However, it is important to understand that this compensation may fail. 4D flow MRI provides a unique insight into this phenomenon.
本研究旨在系统验证二维超声心动图中假设的左心室流出道（LVOT）简化几何形状和血流剖面在评估4D流MRI评估瓣膜疾病效用时是否合适。这项前瞻性研究对37名健康志愿者（年龄：51.9±18.2岁，20名女性）和7名主动脉瓣狭窄（AS）患者（年龄：64.2±9.6岁，1名女性）同日进行了多普勒超声心动图和4D流MRI检查。研究了超声心动图中用于评估主动脉瓣面积的两个关键假设，即（1）LVOT形状为圆形和（2）通过LVOT的速度剖面为平坦的假设。将4D流MRI获得的三维速度和形状信息用作对照。结果发现，在健康组和AS组中，超声心动图测得的LVOT面积较低（分别低26.5%和24.5%），速度时间积分（VTI）较高（分别高28.5%和30.2%）。在检查个体和队列平均LVOT每搏输出量时，这些相互矛盾的误差在很大程度上相互抵消。超声心动图和4D流MRI测得的LVOT面积、VTI和每搏输出量分别为3.6±0.7 vs. 4.9±1.0 cm²（p<0.001）、21.2±3.0 vs 15.2±2.8 cm（p<0.001）和75.6±15.6 vs 72.8±14.1 ml（p=0.3376）。在LVOT面积和VTI的总体平均值中，低估和高估似乎相互补偿，从而得出“实际”的每搏输出量。然而，重要的是要明白这种补偿可能会失败。4D流MRI为这一现象提供了独特的见解。
