中文摘要：

目的观察自制载超顺磁性氧化铁（SPIO）高分子微球（s-PLGA）对兔肝癌MR成像效果的影响。方法双乳化法制备载SPIO的高分子微球。建立兔VX2肝癌模型12只，于肿瘤种植后21天将随机分为3组，分别经耳缘静脉注入s-PLGA（s-PLGA组）、生理盐水（生理盐水组）以及PLGA1ml／kg体质量（PLGA组）。注射前、后行MR平扫及增强扫描，分别测量肝实质和肿瘤的信号强度，计算肿瘤／肝实质信号强度比。扫描结束后处死动物，取肝癌标本行HE及普鲁士蓝染色，于显微镜下观察。结果制备的s—PLGA呈规则球形，直径约800nm。MR成像显示，注射s-PLGA后，肝实质信号强度显著下降，肿瘤信号无明显变化，肿瘤／肝实质信号强度比相对高，明显高于生理盐水及PLGA组（P〈0．05）。普鲁士蓝染色显示，s-PLGA组兔肝实质内有较多蓝染颗粒分布。结论自制s-PLGA能有效增强兔肝脏肿瘤与正常组织间的信号强度对比，对诊断肝癌可能具有一定应用价值。

英文摘要：

Objective To investigate the influence of self-made superparamagnetic iron oxide （SPIO） loaded polymer mi- crospheres （s-PLGA） on MR imaging for liver tumor in rabbits. Methods Double emulsion method was utilized to prepare the s-PLGA. Twenty-one days after implantation of VX2 tumor in liver, 12 rabbits were randomly and equally divided into three groups with the injection of s-PLGA （s-PLGA group）, saline （saline group）, and PLGA 1 ml/kg （PLGA group） via ear vein respectively. MR imaging was performed before and after injection of the above three agents, the signal intensity （SI） of liver parenchyma and liver tumor were measured, then the signal ratio of liver tumor to liver parenchyma was calcu- lated before and after enhancement. After MR scanning, the rabbits were sacrificed, and Prussian blue and HE staining of the livers were done. Results The s-PLGA microcapsules were observed with regular spherical morphology, and the aver- age size of s-PLGA was about 800 nm. After injection of s-PLGA, SI of liver parenchyma reduced markedly, while no sig- nificant changes of SI were found in liver tumors, and the signal ratio of liver tumor to liver parenchyma increased signifi- cantly compared with the other two groups （P〈0.05）. Accumulation of blue particles within liver parenchyma was ob- served in s-PLGA group. Conclusion The self-made s-PLGA microspheres can effectively enhance SI contrast between the tumor and normal liver tissue in rabbits, which may having potential application value in the detection of liver cancer.