探讨经胎鼠脐静脉注射不同剂量六氟化硫微泡造影剂(SHM)，进行超声造影(CEUS)时设置不同机械指数(MI)值，对晚孕期SD大鼠胎盘胎儿面CEUS成像效果的影响。

选择40只晚孕期SD大鼠为研究对象，采用随机数字表法，将其分为A、B、C、D组，每组各10只。对孕鼠进行CEUS时，A、B、C、D组经胎鼠脐静脉注射SHM剂量分别为0.03、0.06、0.09、0.12 mL/kg；采用对比脉冲序列(CPS)成像技术，设置的MI值分别为0.10、0.15、0.20、0.25及0.30。采用时间-强度曲线(TIC)法对CEUS成像效果进行定量分析，本研究观察的3项TIC测量指标包括注射SHM后的到达时间(AT)、达峰时间(TTP)及峰值强度(PI)。采用单因素方差分析及最小显著性差异法(LSD)-t检验，对调整SHM不同剂量及设置不同MI值时，上述3项指标进行总体比较及两两比较。

①对C组孕鼠胎盘胎儿面进行CEUS的结果显示：将MI值从0.10上调至0.30时，AT及TTP均无显著变化(P>0.05)；将MI值从0.10上调至0.20时，PI随MI值增加而增加(P<0.05)，设置MI值为0.20时，PI达最大值；而MI值从0.20上调至0.30时，PI则无显著变化(P>0.05)。②设置MI值为0.20时，4组孕鼠胎盘胎儿面CEUS的结果显示：C组AT、TTP、PI分别为(0.95±0.45) s、(7.9±3.0) s、(30.6±4.2) dB，与A组的(1.67±0.83) s、(12.5±2.8) s、(25.5±4.8) dB比较，差异均有统计学意义(P＝0.004、0.001、0.004)；C组这3项指标与B、D组比较，差异则均无统计学意义(P>0.05)。B组AT、TTP与D组比较，差异均有统计学意义(P<0.05)；而B组的3项指标与A组比较，以及PI与D组比较，差异则均无统计学意义(P>0.05)。D组的3项指标与A组比较，差异均有统计学意义(P<0.05)。随造影剂剂量增加，AT和TTP缩短，PI则增加。

对晚孕期SD大鼠胎盘胎儿面进行CEUS，成像效果最佳的SHM剂量为0.09 mL/kg、MI值为0.20。

To investigate influence of different contrast agent injection doses of sulphur hexafluoride microbubbles (SHM) through fetal rats′ umbilical veins and different mechanical indexes (MI) setting on imaging quality of contrast-enhanced ultrasound (CEUS) in placental fetal surface of SD rats in late pregnancy.

Forty SD rats in late pregnancy were selected as study subjects. According to random number table method, they were divided into A, B, C and D groups each group with 10 rats, and doses of SHM were 0.03, 0.06, 0.09 and 0.12 mL/kg, respectively during CEUS. Meanwhile, contrast pulse sequence (CPS) imaging technology was used and MI were set as 0.10, 0.15, 0.20, 0.25 and 0.30 in each group. The quantitative analysis was conducted by time-intensity curve (TIC) method for CEUS imaging quality, and 3 indexes measured by TIC for this study included arrival time (AT), time to peak (TTP) and peak intensity (PI) after SHM was injected. One-way ANOVA and least significant difference (LSD)-t test were used for overall comparison and further comparison between each two groups of above 3 indexes when adjusted different SHM doses and set different MI.

① Results of CEUS in placental fetal surface of pregnant rats in C group: when MI setting increased from 0.10 to 0.30, there were no significant differences in AT and TTP (P>0.05). When MI setting increased from 0.10 to 0.20, PI increased with increased of MI (P<0.05), and PI reached the maximum when MI setting was 0.20. When MI setting increased from 0.20 to 0.30, PI showed no significant difference (P>0.05). ② CEUS results of placental fetal surface of pregnant rats in 4 groups when MI setting was 0.20: AT, TTP and PI of C group were (0.95±0.45) s, (7.9±3.0) s and (30.6±4.2) dB, which were significantly different from (1.67±0.83) s, (12.5±2.8) s and (25.5±4.8) dB of those in A group, and the differences were statistically significant (P=0.004, 0.001, 0.004). There were no significant differences between C group and B group, also between C group and D group in those 3 indexes (P>0.05). There were significant differences between B group and D group in AT and TTP (P<0.05); However, there were no significant differences between B group and A group in those 3 indexes, and between B group and D group in PI (P>0.05). There were significant differences between D group and A group in those 3 indexes (P<0.05). With contrast agent dose increased, AT and TTP shorten, while PI increased.

When CEUS was performed on the placental fetal surface of SD rats in late pregnancy, SHM dose was 0.09 mL/kg and MI setting was 0.20 that CEUS may had best imaging quality.