Department of Radiology and Biomedical Imaging, University of California, San Francisco , San Francisco, CA 94121; Vascular Imaging Research Center, San Francisco Veteran Affairs Medical Center, San Francisco, CA 94121.
Department of Surgery, University of California, San Francisco, San Francisco, CA 94121; Department of Cardiac Surgery, San Francisco Veteran Affairs Medical Center, San Francisco, CA 94121.
J Biomech Eng. 2024 Dec 1;146(12). doi: 10.1115/1.4066430.
Ascending thoracic aortic aneurysms (aTAAs) can lead to life-threatening dissection and rupture. Recent studies have highlighted aTAA mechanical properties as relevant factors associated with progression. The aim of this study was to quantify in vivo aortic wall stretch in healthy participants and aTAA patients using displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging. Moreover, aTAA wall stretch between surgical and nonsurgical patients was investigated. Finally, DENSE measurements were compared to reference-standard mechanical testing on aTAA specimens from surgical repairs. In total, 18 subjects were recruited, six healthy participants and 12 aTAA patients, for this prospective study. Electrocardiogram-gated DENSE imaging was performed to measure systole-diastole wall stretch, as well as the ratio of aTAA stretch to unaffected descending thoracic aorta stretch. Free-breathing and breath-hold DENSE protocols were used. Uniaxial tensile testing-measured indices were correlated to DENSE measurements in five harvested specimens. in vivo aortic wall stretch was significantly lower in aTAA compared to healthy subjects (1.75±1.44% versus 5.28±1.92%, respectively, P = 0.0004). There was no correlation between stretch and maximum aTAA diameter (P = 0.56). The ratio of aTAA to unaffected thoracic aorta wall stretch was significantly lower in surgical candidates compared to nonsurgical candidates (0.993±0.011 versus 1.017±0.016, respectively, P = 0.0442). Finally, in vivo aTAA wall stretch correlated to wall failure stress and peak modulus of the intima (P = 0.017 and P = 0.034, respectively), while the stretch ratio correlated to whole-wall thickness failure stretch and stress (P = 0.013 and P = 0.040, respectively). Aortic DENSE has the potential to assess differences in aTAA mechanical properties and progressions.
升主动脉瘤（aTAA）可导致危及生命的夹层和破裂。最近的研究强调了 aTAA 的机械性能是与进展相关的重要因素。本研究的目的是使用位移编码激励回波（DENSE）磁共振成像定量测量健康参与者和 aTAA 患者的主动脉壁拉伸。此外，还研究了手术和非手术患者之间的 aTAA 壁拉伸。最后，将 DENSE 测量值与手术修复的 aTAA 标本的参考标准机械测试进行了比较。在这项前瞻性研究中，共招募了 18 名受试者，其中 6 名健康参与者和 12 名 aTAA 患者。进行心电图门控 DENSE 成像以测量收缩期-舒张期壁拉伸以及 aTAA 拉伸与未受影响的降主动脉拉伸的比值。使用自由呼吸和屏气 DENSE 方案。在五个收获的标本中，将单轴拉伸测试测量的指数与 DENSE 测量值相关联。与健康受试者相比，aTAA 患者的主动脉壁拉伸明显较低（分别为 1.75±1.44%和 5.28±1.92%，P = 0.0004）。拉伸与最大 aTAA 直径之间没有相关性（P = 0.56）。与非手术候选者相比，手术候选者的 aTAA 与未受影响的胸主动脉壁拉伸的比值明显较低（分别为 0.993±0.011 和 1.017±0.016，P = 0.0442）。最后，体内 aTAA 壁拉伸与壁失效应力和内膜峰值模量相关（P = 0.017 和 P = 0.034），而拉伸比与全壁厚度失效拉伸和应力相关（P = 0.013 和 P = 0.040）。主动脉 DENSE 有可能评估 aTAA 机械性能和进展的差异。
