Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia; PAI+ Research Group, Energetics and Mechanics Department, Universidad Autónoma de Occidente, Cali, Colombia.
J Am Soc Echocardiogr. 2021 Nov;34(11):1211-1223. doi: 10.1016/j.echo.2021.06.011. Epub 2021 Jun 29.
Mitral regurgitation (MR) quantification by the proximal isovelocity surface area (PISA) method remains challenging. Using computer models, the authors evaluated the accuracy of different PISA methods and quantified their errors.
Five functional MR computer models of different geometric and tethering abnormalities were created, validated, and treated as phantom models, from which the reference values were directly obtained. Virtual two-dimensional (2D) PISA and three-dimensional (3D) PISA (both peak and integrated values) were performed on these phantom models. By comparing virtual PISA results with reference values, the accuracy of different PISA methods was evaluated, and their sources of errors were quantified.
Compared with reference values of regurgitant flow rate, excellent correlations were found for true PISA (r = 0.99, bias = 32.3 ± 35.3 mL/sec), 3D PISA (r = 0.97, bias = -24.4 ± 55.5 mL/sec), followed by multiplane 2D hemicylindrical PISA (r = 0.88, bias = -24.1 ± 85.4 mL/sec) and hemiellipsoidal PISA (r = 0.91, bias = -55.7 ± 96.6 mL/sec). Weaker correlations were found for single-plane 2D hemispherical PISA (parasternal long-axis: r = 0.71, bias = -77.6 ± 124.5 mL/sec; apical two-chamber: r = 0.69, bias = -52.0 ± 122.0 mL/sec; apical four-chamber: r = 0.82, bias = -65.5 ± 107.3 mL/sec). For regurgitant volume quantification, integrated PISA was more accurate than peak PISA. The bias of 3D PISA improved from -12.7 ± 7.8 mL (peak PISA) to -2.1 ± 5.3 mL (integrated PISA).
For functional MR quantification, 2D hemispherical PISA had significant underestimation, multiplane 2D hemiellipsoidal and hemicylindrical PISA showed improved accuracy, and 3D PISA was the most accurate. The PISA method is subject to both systematic underestimation due to the Doppler angle effect and systematic overestimation when regurgitant flow is not perpendicular to PISA contour. Integrated PISA is able to capture dynamic MR and is therefore more accurate than peak PISA. The sum of regurgitant flow rates is the most feasible way to perform integrated PISA.
使用近等速表面积（PISA）方法定量二尖瓣反流（MR）仍然具有挑战性。作者通过计算机模型评估了不同 PISA 方法的准确性，并量化了它们的误差。
创建了五个不同几何形状和牵张异常的功能性 MR 计算机模型，对其进行了验证，并将其作为幻影模型进行处理，可直接从这些幻影模型中获得参考值。对这些幻影模型进行了虚拟二维（2D）PISA 和三维（3D）PISA（峰值和积分值）。通过将虚拟 PISA 结果与参考值进行比较，评估了不同 PISA 方法的准确性，并量化了它们的误差来源。
与射流率的真实参考值相比，真实 PISA（r=0.99，偏差=32.3±35.3mL/sec）、3D PISA（r=0.97，偏差=-24.4±55.5mL/sec）具有极好的相关性，其次是多平面 2D 半圆柱 PISA（r=0.88，偏差=-24.1±85.4mL/sec）和半椭圆 PISA（r=0.91，偏差=-55.7±96.6mL/sec）。单平面 2D 半球形 PISA（胸骨旁长轴：r=0.71，偏差=-77.6±124.5mL/sec；心尖两腔：r=0.69，偏差=-52.0±122.0mL/sec；心尖四腔：r=0.82，偏差=-65.5±107.3mL/sec）的相关性较弱。对于反流容积的定量，积分 PISA 比峰值 PISA 更准确。3D PISA 的偏差从-12.7±7.8mL（峰值 PISA）改善至-2.1±5.3mL（积分 PISA）。
对于功能性磁共振定量，2D 半球形 PISA 存在显著低估，多平面 2D 半椭圆和半圆柱 PISA 显示出改进的准确性，而 3D PISA 是最准确的。PISA 方法既受到由于多普勒角度效应导致的系统低估，也受到反流流不是垂直于 PISA 轮廓时的系统高估的影响。积分 PISA 能够捕获动态 MR，因此比峰值 PISA 更准确。反流速率之和是执行积分 PISA 最可行的方法。
