Primary Study On Assessment Of The Safety Of Contrast-enhanced Ultrasonography And Its Application On Placenta Of The Rat

Objective:In this study, a late pregnancy rat was studied to discuss the value of placental contrast-enhanced ultrasonography.Methods:Fifteen late pregnancy rats (Wistar rats, gestational age: rang 18 to 21 days) were selected and divided into three experimental groups, group A as control group with injection of physiologic saline solution (2.0 ml/kg), group B as high dose with 23.6 mg/kg (2.0 ml/kg, 11.8 mg/ml) and group C low dose with injection 0.236 mg/kg (2.0 ml/kg, 0.118 mg/ml) body weight. One of placentas selected randomly of maternal rat was examined by ACUSON Sequoia 512 with contrast pulse sequencing (CPS) technology. Time-intensity curves were generated with the region of interest placed over the placental central arterial canal and intervillous space were by using offline software apparatus-Paragon release (revision 8.0) and statistics methods (Statistica 6.0) in five rats which were injection with high dose of SonoVue?.Results:The contrast enhanced agent do not pass through the placenta barrier and do not reach the villus of placenta. No enhancement was seen after saline solution injections. Intravascular injection of SonoVueTM was capable of delineating the vascular architecture of the villous tree of rat. As expected, Time-intensity curves generated by placement of the region of interest over the placental central arterial canal produced a relatively rapid rise and a more gradual decay of signal intensity, while placement of a similar sized region of interest over the intervillous space produced a relatively lower and shorter effect. The area under the curve and the peak signal intensity of placental central arterial canal is larger than that of the intervillous space. There are significant differences in the two region ( P < 0.05). Conclusion: The CPS technique and SonoVueTM limpidly delineate placental angioarchitecture in a rat model. The time-intensity curves would reflect the feature of blood concentration in placental central arterial canal and intervillous space. If validated by further study, this may allow investigators to apply the method and indicator-dilution theory to evaluate intervillous blood flow. Objective:To observe the change of placental ultrastructure with contrast-enhanced ultrasonography in the late trimester of pregnant rat and whether hemodynamic effects on the fetus occur in late pregnancy rat in the performance of ultrasound contrast agent (UCA) SonoVue TM .Methods:Sixty pregnant rats in the late stages (Wister rat, median weight, 300 g; range, 260 g to 330 g; median gestational age, 19 days; rang, 18 to 21 days) were divided into three experimental groups randomly, group A as control group with injection of normal saline solution(2.0ml/kg), group B as high dose with injection 23.6 mg/kg body weight(2.0 ml/kg, 11.8 mg/ml, group C as low dose with injection 0.236 mg/kg body weight (2.0 ml/kg, 0.118 mg/ml). Every placenta of maternal rat was examined by ACUSON Sequoia 512 with contrast pulse sequencing (CPS) technology. The machine index was 0.23, it was injected in the tail vein with the contrast agent and normal saline solution. In each group the hemodynamics of fifteen pregnant rats were measured with doppler technique. Resistance index (RI), pulsatility index (PI), and systolic-diastolic ratio (S/D) were measured in the fetal umbilical artery, the fetal middle cerebral artery and the maternal uterine artery before and after administration of UCA or physiologic saline solution. Tissueslices of the placenta of five pregnant rats in each group were collected for microscope investigation after examination.Results:There were no significant different about these parameters (RI, PI and S/D in the the fetal umbilical artery, fetal middle cerebral artery and the maternal uterine artery) among four groups (contain base group)( P>0.05). Patho-change was not found in placenta of three groups with microscope. There were no significant ultramicro- changes of the placenta of groupA and group C with electron-scope. Increasing cytolysosome, glycogen deposition, enlargement of rough endoplasmic reticulum, and vacuolization in the cytoplasm of syncytio trophoblasts were found in group B.Conclusion: Contrast-enhanced ultrasonography does not affect the hemodynamic parameters of placenta. In the condition of our experiment the damage to the microstructure of syncytiotrophoblasts don't happen, but the change of subcellular organelle in the syncytiotrophoblasts could be found in the low mechanical index.