肝低机械指数灰阶超声造影定量分析的实验研究

Low mechanical index gray-scale contrast enhancement and qualification in rabbit liver

目的:探讨肝脏不同部位灰阶超声造影效应及肝恶性肿瘤对其周围肝实质血流动力学的影响。方法:13只新西兰大白兔随机分为两组。A组5只,分别在8个剂量水平(剂量范围:0.02～0.16ml/kg)团注超声造影剂以寻找理想的造影剂量;B组8只,分别经耳缘静脉对其荷VX2瘤前、后团注超声造影剂,应用低机械指数灰阶超声造影和时间强度曲线,定量分析边缘部位及中心部位肝实质以及荷瘤前、后肝实质造影增强效应。结果:①在0.02～0.10ml/kg范围内,造影剂剂量与门静脉峰值信号强度呈直线相关关系(r=0.89);在0.02～0.12ml/kg范围内,造影剂剂量与肝实质峰值信号强度呈直线相关关系(r=0.92)。0.10ml/kg是兔理想的造影剂量;②与边缘部位肝实质相比,中心部位肝实质造影剂开始增强时间和达到峰值时间均较早,峰值强度较强,渡越时间较长。除左肝造影剂渡越时间外,肝脏中心部位与边缘部位各造影定量参数间差异具有统计学意义(P<0.05);③与荷瘤前相比,荷瘤后肝实质造影剂开始增强时间和达到峰值时间均较早,峰值强度较强,渡越时间较短,但其变化轻微,荷瘤前、后肝实质各造影定量参数间差异均无统计学意义(P>0.05)。结论:①边缘部位及中心部位肝实质超声造影定量参数不同;②灰阶超声造影不能完全反映肝脏恶性肿瘤对其周围肝实质血流动力学影响;肝实质超声造影定量分析对肝脏恶性肿瘤的诊断及预示价值尚待进一步研究。

Objective： To evaluate the difference between central and peripheral position of contrast gray-scale imaging in rabbit liver and to study the hemodynamic changes of peri-neoplastic liver parenchyma with gray-scale contrast enhancement. Methods： Ultrasound contrast agent（UCA） SonoVue^TM in eight different doses （0.02 ml/kg to 0.16 ml/kg） was applied as a bolus in a marginal ear vein respectively in five normal rabbits to gain an optimal dose for liver perfusion study. SonoVueTM （0.1 ml/kg） was applied respectively in 8 rabbits before and after VX2-bearing by intravenous bolus injection. Flow-related parameters such as time to enhancement （ET）, time to peak intensity（PIT）, PSI, and mean transit time （MTT） sured using low mechanical index contrast gray-scale imaging and Wash-in/Wash-out time were meaintensity curve software. Results： There was a linear correlation between the dosage （ranged from 0.02 to 0.10 ml/kg） and portal peak intensity （r=0.89）, and between the dosage （ranged from 0.02 to 0.12 ml/kg） and liver parenchyma peak intensity （r=0.92）. The ideal dosage was 0.10 ml/kg. There was significant difference of parameters of the time-intensity curve between central position and peripheral position of parenchyma （P〈0.05）, except for the MTT of left liver. The ET and PIT were earlier, the PSI was higher, and the MTT was longer in central position of parenchyma than those in peripheral position. The ET and PIT were slightly earlier, the PSI was higher and the MTT was shorter in peri-neoplastic liver parenchyma of VX2-bearing than those of none VX2- bearing. However, there was no significant difference of parameters of the time-intensity curve of liver parenchyma between before and after VX2-bearing of rabbit （P〉0.05）. Conclusion： The parameters of time-intensity curve are influenced intensely by different UCA doses. The flow parameters are different between central and peripheral position of hepatic parenchyma. It is much valuable to relate quantitative parameters to quantitative position for disease diagnosis and differential diagnosis. In addition, gray-scale contrast enhancement does not fully evaluate the hemodynamic changes of peri-neoplastic liver parenchyma. Thus, it is less valuable to relate quantitative parameters of peri-neoplastic liver parenchyma to malignant tumor diagnosis.