Rosado-Mendez Ivan M, Palmeri Mark L, Drehfal Lindsey C, Guerrero Quinton W, Simmons Heather, Feltovich Helen, Hall Timothy J
Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Biomedical Engineering, Duke University, Durham, North Carolina, USA.
Ultrasound Med Biol. 2017 Apr;43(4):790-803. doi: 10.1016/j.ultrasmedbio.2016.12.006. Epub 2017 Feb 8.
Shear wave elasticity imaging has shown promise in evaluation of the pregnant cervix. Changes in shear wave group velocity have been attributed exclusively to changes in stiffness. This assumes homogeneity within the region of interest and purely elastic tissue behavior. However, the cervix is structurally/microstructurally heterogeneous and viscoelastic. We therefore developed strategies to investigate these complex tissue properties. Shear wave elasticity imaging was performed ex vivo on 14 unripened and 13 misoprostol-ripened cervix specimens from rhesus macaques. After tests of significant and uniform shear wave displacement, as well as reliability of estimates, group velocity decreased significantly from the distal (vaginal) to proximal (uterine) end of unripened, but not ripened, specimens. Viscosity was quantified by the slope of the phase velocity versus frequency. Dispersion was observed in both groups (median: 5.5 m/s/kHz, interquartile range: 1.5-12.0 m/s/kHz), also decreasing toward the proximal cervix. This work suggests that comprehensive assessment of complex tissues such as cervix requires consideration of structural heterogeneity and viscosity.
剪切波弹性成像在评估妊娠宫颈方面已显示出前景。剪切波群速度的变化仅归因于硬度的变化。这假定感兴趣区域内具有同质性且组织行为完全为弹性。然而，宫颈在结构/微观结构上是异质的且具有粘弹性。因此，我们制定了策略来研究这些复杂的组织特性。对来自恒河猴的14个未成熟宫颈标本和13个米索前列醇成熟宫颈标本进行了体外剪切波弹性成像。在对显著且均匀的剪切波位移以及估计的可靠性进行测试后，未成熟标本（而非成熟标本）从远端（阴道端）到近端（子宫端）的群速度显著降低。通过相速度与频率的斜率对粘度进行量化。两组均观察到频散（中位数：5.5米/秒/千赫兹，四分位间距：1.5 - 12.0米/秒/千赫兹），且向宫颈近端也降低。这项工作表明，对宫颈等复杂组织的全面评估需要考虑结构异质性和粘度。
