Maurer M M, Badir S, Pensalfini M, Bajka M, Abitabile P, Zimmermann R, Mazza E
Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland.
Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland.
J Biomech. 2015 Jun 25;48(9):1541-8. doi: 10.1016/j.jbiomech.2015.02.038. Epub 2015 Feb 26.
Measuring the stiffness of the uterine cervix might be useful in the prediction of preterm delivery, a still unsolved health issue of global dimensions. Recently, a number of clinical studies have addressed this topic, proposing quantitative methods for the assessment of the mechanical properties of the cervix. Quasi-static elastography, maximum compressibility using ultrasound and aspiration tests have been applied for this purpose. The results obtained with the different methods seem to provide contradictory information about the physiologic development of cervical stiffness during pregnancy. Simulations and experiments were performed in order to rationalize the findings obtained with ultrasound based, quasi-static procedures. The experimental and computational results clearly illustrate that standardization of quasi-static elastography leads to repeatable strain values, but for different loading forces. Since force cannot be controlled, this current approach does not allow the distinction between a globally soft and stiff cervix. It is further shown that introducing a reference elastomer into the elastography measurement might overcome the problem of force standardization, but a careful mechanical analysis is required to obtain reliable stiffness values for cervical tissue. In contrast, the maximum compressibility procedure leads to a repeatable, semi-quantitative assessment of cervical consistency, due to the nonlinear nature of the mechanical behavior of cervical tissue. The evolution of cervical stiffness in pregnancy obtained with this procedure is in line with data from aspiration tests.
测量子宫颈的硬度可能有助于预测早产，这是一个全球范围内仍未解决的健康问题。最近，一些临床研究探讨了这个话题，提出了评估子宫颈力学特性的定量方法。准静态弹性成像、使用超声的最大压缩性以及抽吸试验已被用于此目的。用不同方法获得的结果似乎在妊娠期间子宫颈硬度的生理发育方面提供了相互矛盾的信息。进行了模拟和实验，以便使基于超声的准静态程序所获得的结果合理化。实验和计算结果清楚地表明，准静态弹性成像的标准化会导致可重复的应变值，但针对不同的加载力。由于力无法控制，当前这种方法无法区分整体柔软和坚硬的子宫颈。进一步表明，在弹性成像测量中引入参考弹性体可能会克服力标准化的问题，但需要进行仔细的力学分析以获得子宫颈组织可靠的硬度值。相比之下，由于子宫颈组织力学行为的非线性性质，最大压缩性程序可对子宫颈的韧性进行可重复的半定量评估。用此程序获得的妊娠期间子宫颈硬度的变化与抽吸试验的数据一致。
