BackgroundIn patients with bicuspid aortic valve (BAV), 4D flow MRI can quantify regions exposed to abnormal aortic hemodynamics, including high wall shear stress (WSS), a known stimulus for arterial wall dysfunction. However, the long‐term multiscan reproducibility of 4D flow MRI‐derived hemodynamic parameters is unknown.PurposeTo investigate the long‐term stability of 4D flow MRI‐derived peak velocity, WSS, and WSS‐derived heatmaps in patients with BAV undergoing multiyear surveillance imaging.Study TypeRetrospective.Population20 BAV patients (mean age 48.4 ± 13.9 years; 14 males) with five 4D flow MRI scans, with intervals of at least 6 months between scans, and 125 controls (mean age: 50.7 ± 15.8 years; 67 males).Field Strength/Sequence1.5 and 3.0T, prospectively ECG and respiratory navigator‐gated aortic 4D flow MRI.AssessmentAutomated AI‐based 4D flow analysis pipelines were used for data preprocessing, aorta 3D segmentation, and quantification of ascending aorta (AAo) peak velocity, peak systolic WSS, and heatmap‐derived relative area of elevated WSS compared to WSS ranges in age and sex‐matched normative control populations. Growth rate was derived from the maximum AAo diameters measured on the first and fifth MRI scans.Statistical TestsOne‐way repeated measures analysis of variance. P < 0.05 indicated significance.ResultsOne hundred 4D flow MRI exams (five per patient) were analyzed. The mean total follow‐up duration was 5.5 ± 1.1 years, and the average growth rate was 0.3 ± 0.2 mm/year. Peak velocity, peak systolic WSS, and relative area of elevated WSS did not change significantly over the follow‐up period (P = 0.64, P = 0.69, and P = 0.35, respectively). The patterns and areas of elevated WSS demonstrated good reproducibility on semiquantitative assessment.Conclusion4D flow MRI‐derived peak velocity, WSS, and WSS‐derived heatmaps showed good multiyear and multiscan stability in BAV patients with low aortic growth rates. These findings underscore the reliability of these metrics in monitoring BAV patients for potential risk of dilation.Level of Evidence3Technical EfficacyStage 1

中文翻译：

---

通过 4D 流 MRI 评估二叶式主动脉瓣患者主动脉壁剪切应力的多年间隔变化

背景对于二叶式主动脉瓣 (BAV) 患者，4D 流 MRI 可以量化暴露于异常主动脉血流动力学的区域，包括高壁剪切应力 (WSS)，这是一种已知的动脉壁功能障碍刺激因素。然而，4D 流 MRI 衍生的血流动力学参数的长期多次扫描重现性尚不清楚。目的研究接受多年监测成像的 BAV 患者中 4D 流 MRI 衍生的峰值速度、WSS 和 WSS 衍生的热图的长期稳定性研究类型回顾性人群 20 名 BAV 患者（平均年龄 48.4 ± 13.9 岁；14 名男性）进行了 5 次 4D 流 MRI 扫描，扫描之间的间隔至少为 6 个月，以及 125 名对照者（平均年龄：50.7 ± 15.8 岁；67 名男性）场强/序列1.5和3.0T、前瞻性心电图和呼吸导航门控主动脉4D血流MRI。评估基于自动化AI的4D血流分析管道用于数据预处理、主动脉3D分割和升主动脉（AAo）峰值的量化与年龄和性别匹配的规范对照人群中的 WSS 范围相比，速度、峰值收缩期 WSS 以及由热图得出的升高的 WSS 相对面积。生长率源自第一次和第五次 MRI 扫描测量的最大 AAO 直径。统计测试单向重复测量方差分析。磷< 0.05 表示显着性。结果分析了一百个 4D 流 MRI 检查（每个患者 5 个）。平均总随访时间为 5.5 ± 1.1 年，平均生长率为 0.3 ± 0.2 毫米/年。峰值速度、峰值收缩期 WSS 和升高的 WSS 相对面积在随访期间没有显着变化（磷= 0.64,磷= 0.69，并且磷= 0.35，分别）。WSS 升高的模式和面积在半定量评估中表现出良好的可重复性。结论 4D 流 MRI 衍生的峰值速度、WSS 和 WSS 衍生的热图在主动脉生长率较低的 BAV 患者中显示出良好的多年和多次扫描稳定性。这些发现强调了这些指标在监测 BAV 患者潜在扩张风险方面的可靠性。证据级别 3 技术功效阶段 1