Purpose

Preeclampsia (PE) is a pregnancy complication of abnormally elevated blood pressure and organ damage where endothelial function is impaired. Wall shear stress (WSS) strongly effects endothelial cell morphology and function but in PE the WSS values are unknown. WSS calculations from ultrasound inaccurately assume cylindrical arteries and patient specific computational fluid dynamics (CFD) typically require time-consuming 3D imaging such as CT or MRI.

Methods

Two-dimensional (2D) B-mode ultrasound images were lofted together to create simplified three-dimensional (3D) geometries of the brachial artery (BA) that incorporate artery curvature and non-circular cross sections. This process was efficient and on average took 120 ± 10 s. Patient specific CFD was then performed to quantify BA WSS for a small cohort of PE (n = 5) and normotensive pregnant patients (n = 5) and compared against WSS calculations assuming a cylindrical artery.

Results

For several WSS metrics (time averaged WSS (TAWSS), peak systolic WSS, oscillatory shear index (OSI), OSI/TAWSS and relative residence time) CFD on the simplified arterial geometries calculated large spatial differences in WSS that assuming a cylindrical artery cannot calculate. Bland–Altman and intra-class correlation (ICC) analyses found assuming a cylindrical artery both underestimated (p < 0.05) and had poor agreement (ICC < 0.5) with the maximum WSS values from CFD. WSS values that were abnormal compared to the normotensive patients (OSI = 0.014 ± 0.026) appear related to the pregnancy complications fetal growth restriction (n = 2, OSI = 0.14, 0.25) and gestational diabetes (n = 1, OSI = 0.23).

Conclusion

Creating 3D artery geometries from 2D ultrasound images can be used for CFD simulations to calculate WSS from ultrasound without assuming cylindrical arteries. This approach requires minimal time for both medical imaging and CFD analysis.

中文翻译：

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子痫前期妊娠肱动脉壁剪应力的超声计算流体动力学评估

目的

先兆子痫 (PE) 是一种妊娠并发症，包括异常升高的血压和内皮功能受损的器官损伤。壁剪切应力 (WSS) 强烈影响内皮细胞的形态和功能，但在 PE 中，WSS 值是未知的。来自超声的 WSS 计算不准确地假设圆柱动脉和患者特定的计算流体动力学 (CFD) 通常需要耗时的 3D 成像，例如 CT 或 MRI。

方法

将二维 (2D) B 型超声图像放样在一起以创建包含动脉曲率和非圆形横截面的肱动脉 (BA) 的简化三维 (3D) 几何形状。这个过程是有效的，平均需要 120 ± 10 秒。然后进行患者特异性 CFD 以量化一小群 PE（n  = 5）和血压正常的妊娠患者（n  = 5）的 BA WSS，并与假设圆柱动脉的 WSS 计算进行比较。

结果

对于几个 WSS 指标（时间平均 WSS (TAWSS)、峰值收缩 WSS、振荡剪切指数 (OSI)、OSI/TAWSS 和相对停留时间），简化动脉几何形状上的 CFD 计算了假设圆柱形动脉无法计算的 WSS 中的大空间差异. Bland-Altman 和组内相关性 (ICC) 分析发现，假设圆柱动脉被低估 ( p  < 0.05) 并且与 CFD 的最大 WSS 值的一致性较差 (ICC < 0.5)。与正常血压患者相比，异常的 WSS 值 (OSI = 0.014 ± 0.026) 似乎与妊娠并发症胎儿生长受限 ( n  = 2, OSI = 0.14, 0.25) 和妊娠糖尿病 ( n  = 1, OSI = 0.23) 有关。

结论

从 2D 超声图像创建 3D 动脉几何形状可用于 CFD 模拟，以根据超声计算 WSS，而无需假设圆柱形动脉。这种方法需要最少的时间进行医学成像和 CFD 分析。