While proximal isovelocity surface area (PISA) method is one of the most common echocardiographic methods for quantitative mitral regurgitation (MR) assessment, accurate MR quantification remains challenging. This study examined the theoretical background of PISA, performed virtual echocardiography on computer models of functional MR, and quantified different sources of errors in PISA. For regurgitant flow rate measurement, the conventional 2D hemispherical PISA caused significant underestimation due to underestimation of PISA area, the multiplane 2D hemiellipsoidal and hemicylindrical PISA provided improved accuracy with better assumptions on PISA contour shape. With the direct capture of PISA area, the 3D-PISA was found to be the most accurate. However, it should be noted that PISA method is subject to systematic underestimation due to the Doppler angle effect, and systematic overestimation due to the “flow direction angle” between the regurgitant flow direction and the PISA contour normal direction. For regurgitant volume quantification, integrated PISA, when performed properly, was able to capture the dynamic MR and therefore was more accurate than peak PISA. In specific, integrated PISA using the sum of regurgitant flow rates is recommended.

中文翻译：

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功能性二尖瓣关闭不全的定量超声心动图评估的计算分析：近端等速表面积 (PISA) 方法

虽然近端等速表面积 (PISA) 方法是用于定量二尖瓣关闭不全 (MR) 评估的最常见的超声心动图方法之一，但准确的 MR 量化仍然具有挑战性。本研究检查了 PISA 的理论背景，对功能性 MR 的计算机模型进行了虚拟超声心动图，并量化了 PISA 中的不同错误来源。对于反流流速测量，传统的 2D 半球形 PISA 由于低估了 PISA 面积而导致显着低估，多平面 2D 半椭圆形和半圆柱形 PISA 提供了更高的精度，更好地假设了 PISA 轮廓形状。通过直接捕获 PISA 区域，发现 3D-PISA 是最准确的。然而，需要注意的是，PISA法由于多普勒角效应存在系统性低估，反流流向与PISA轮廓法线方向之间存在“流向角”，存在系统性高估。对于反流体积量化，积分 PISA 在正确执行时能够捕获动态 MR，因此比峰值 PISA 更准确。具体而言，推荐使用反流流速总和的综合 PISA。