BACKGROUND Displacement Encoding with Stimulated Echoes (DENSE) cardiovascular magnetic resonance (CMR) of the aortic wall offers the potential to improve patient-specific diagnostics and prognostics of diverse aortopathies by quantifying regionally heterogeneous aortic wall strain in vivo. However, before regional mapping of strain can be used to clinically assess aortic pathology, an evaluation of the natural variation of normal regional aortic kinematics is required. METHOD Aortic spiral cine DENSE CMR was performed at 3 T in 30 healthy adult subjects (range 18 to 65 years) at one or more axial locations that are at high risk for aortic aneurysm or dissection: the infrarenal abdominal aorta (IAA, n = 11), mid-descending thoracic aorta (DTA, n = 17), and/or distal aortic arch (DAA, n = 11). After implementing custom noise-reduction techniques, regional circumferential Green strain of the aortic wall was calculated across 16 sectors around the aortic circumference at each location and normalized by the mean circumferential strain for comparison between individuals. RESULTS The distribution of normalized circumferential strain (NCS) was heterogeneous for all locations evaluated. Despite large differences in mean strain between subjects, comparisons of NCS revealed consistent patterns of strain distribution for similar groupings of patients by axial location, age, and/or mean displacement angle. NCS at local systole was greatest in the lateral/posterolateral walls in the IAAs (1.47 ± 0.27), medial wall in anteriorly displacing DTAs (1.28 ± 0.20), lateral wall in posteriorly displacing DTAs (1.29 ± 0.29), superior curvature in DAAs < 50 years-old (1.93 ± 0.22), and medial wall in DAAs > 50 years (2.29 ± 0.58). The distribution of strain was strongly influenced by the location of the vertebra and other surrounding structures unique to each location. CONCLUSIONS Regional in vivo circumferential strain in the adult aorta is unique to each axial location and heterogeneous around its circumference, but can be grouped into consistent patterns defined by basic patient-specific metrics following normalization. The heterogeneous strain distributions unique to each group may be due to local peri-aortic constraints (particularly at the aorto-vertebral interface), heterogeneous material properties, and/or heterogeneous flow patterns. These results must be carefully considered in future studies seeking to clinically interpret or computationally model patient-specific aortic kinematics.

中文翻译：

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使用 DENSE 心血管磁共振评估胸主动脉和腹主动脉标准化圆周应变的区域分布。


背景主动脉壁的受激回波（DENSE）心血管磁共振（CMR）位移编码通过量化体内区域异质主动脉壁应变，提供了改善不同主动脉病的患者特异性诊断和预后的潜力。然而，在应变区域图可用于临床评估主动脉病理学之前，需要评估正常区域主动脉运动学的自然变化。方法 在 30 名健康成年受试者（范围 18 至 65 岁）中，在主动脉瘤或夹层高风险的一个或多个轴向位置，以 3 T 进行主动脉螺旋电影 DENSE CMR：肾下腹主动脉（IAA，n = 11） ）、中降胸主动脉（DTA，n = 17）和/或远端主动脉弓（DAA，n = 11）。实施定制降噪技术后，在每个位置围绕主动脉周长的 16 个扇区计算主动脉壁的局部周向格林应变，并通过平均周向应变进行归一化，以便在个体之间进行比较。结果 对于所有评估的位置，归一化周向应变 (NCS) 的分布是不均匀的。尽管受试者之间的平均应变存在很大差异，但 NCS 的比较揭示了按轴向位置、年龄和/或平均位移角划分的相似患者分组的应变分布模式一致。局部收缩时的 NCS 在 IAA 的外侧/后外侧壁中最大 (1.47 ± 0.27)，在前移 DTA 中内侧壁 (1.28 ± 0.20)，在后移 DTA 中侧壁 (1.29 ± 0.29)，在 DAA 中上曲率 < 50 岁 (1.93 ± 0.22)，DAA 内侧壁 > 50 岁 (2.29 ± 0.58)。 应变的分布受到椎骨位置和每个位置特有的其他周围结构的强烈影响。结论 成人主动脉的局部体内周向应变对于每个轴向位置都是独特的，并且在其圆周周围是异质的，但可以根据标准化后的基本患者特定指标分为一致的模式。每组独特的异质应变分布可能是由于局部主动脉周围的限制（特别是在主动脉-椎体界面处）、异质材料特性和/或异质流动模式。在未来寻求临床解释或计算模拟患者特异性主动脉运动学的研究中必须仔细考虑这些结果。