Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Placenta. 2013 Nov;34(11):1009-13. doi: 10.1016/j.placenta.2013.08.014. Epub 2013 Sep 4.
The velocities of the lateral shear waves (Vs; m s⁻¹) generated by an acoustic radiation force impulse (ARFI) correlate with Young's modulus. Therefore, ARFI can be used as a new method to evaluate tissue elasticity. The aim of this study was to investigate the safety of ARFI imaging and the differences in placental elasticity in complicated cases.
The study population included 115 patients between 26 and 41 weeks gestation, who were divided into three groups, namely normal, fetal growth restriction (FGR) and pregnancy-induced hypertension (PIH). After delivery, the Vs values of the placenta were measured ex vivo. After ARFI imaging, microscopic examination was performed, the Vs values were compared among the three groups and the relationship between the Vs values and neonatal birthweight Z-score was investigated.
No histological changes were noted even after ARFI imaging. The Vs values in the FGR group were significantly higher than those in the normal group (1.94 ± 0.74 and 1.31 ± 0.35 m s⁻¹, respectively; p < 0.05). The Vs values demonstrated a significant negative correlation with the Z-score. Moreover, as the Z-score became lower, the Vs values became higher in the range of Z-scores under -0.5 standard deviation (SD).
We speculate that the increased Vs values in the FGR group may have been caused by histological changes, and that a more severe FGR might result in increased Vs values.
ARFI imaging was observed to have no apparent histological damage to the placental tissue. Ex vivo placentas from the FGR group were significantly more firm. Moreover, Vs values and Z-scores of birthweight had a significant negative correlation. Additional investigations are needed about the utility of this method for the evaluation of placental function in vivo.
声辐射力脉冲（ARFI）产生的横向剪切波速度（Vs；m/s）与杨氏模量相关。因此，ARFI 可作为评估组织弹性的新方法。本研究旨在探讨 ARFI 成像的安全性及复杂情况下胎盘弹性的差异。
研究人群包括 115 例 26 至 41 孕周的患者，分为正常、胎儿生长受限（FGR）和妊娠高血压（PIH）三组。分娩后离体测量胎盘 Vs 值。ARFI 成像后行显微镜检查，比较三组间 Vs 值，并探讨 Vs 值与新生儿出生体重 Z 评分的关系。
即使在 ARFI 成像后也未观察到组织学变化。FGR 组的 Vs 值明显高于正常组（分别为 1.94±0.74 和 1.31±0.35 m/s；p<0.05）。Vs 值与 Z 评分呈显著负相关。此外，随着 Z 评分的降低，在低于-0.5 标准差（SD）的 Z 评分范围内，Vs 值升高。
我们推测 FGR 组 Vs 值升高可能与组织学变化有关，更严重的 FGR 可能导致 Vs 值升高。
ARFI 成像未观察到胎盘组织有明显的组织学损伤。FGR 组的离体胎盘明显更硬。此外，Vs 值与出生体重 Z 评分呈显著负相关。需要进一步研究该方法在评估体内胎盘功能方面的应用价值。
