中文摘要：

目的 比较超小超顺磁性氧化铁颗粒（USPIO）增强磁共振成像（MRI）与钆喷替酸葡甲胺（Gd-DPTA）增强MRI两种方法诊断兔颈部反应性增生、肿瘤转移性淋巴结的能力.方法 健康成年新西兰大白兔36只,随机平均分为两组,18只制成颈部淋巴结反应性增生模型,18只制成颈部淋巴结肿瘤转移模型.两组模型各取9只行Gd-DTPA增强MRI,9只行USPIO增强MRI.Gd-DTPA增强前行T1WI、T2WI序列扫描,注射Gd-DPTA后80 s行T1WI扫描.USPIO增强前和注射USPIO后24 h,分别行T1WI、T2WI、T2＊WI序列扫描.分析增强前后淋巴结信号及形态特点,与大体标本及病理结果进行对照分析.结果 肿瘤组内,Gd-DTPA增强MRI诊断转移性淋巴结的敏感度、特异度、阳性预测值、阴性预测值及准确性分别为62.5%、91.3%、88.2%、70.0%及76.6%,而USPIO增强MRI为95.0%、90.9%、90.5%、95.2%及92.9%,两种方法间敏感度和准确性差异有统计学意义（均P＜0.05）.增生组内,Gd-DTPA增强MRI和USPIO增强MRI诊断良性淋巴结的准确性分别为74.2%和87.1%.结论 USPIO增强MRI诊断肿瘤转移性淋巴结的准确性高于Gd-DTPA增强MRI.

英文摘要：

Objective To compare the diagnostic value of gadolinium diethylenetriaminepentaacetic acid （ Gd-DTPA）-enhanced MRI with ultrasmall superparamagnetic iron oxide （ USPIO）-enhanced MRI in differentiating reactive hyperplastic lymph nodes from metastatic lymph nodes in rabbit models.Methods Reactive hyperplastic cervical lymph node model was established in 18 rabbits as hyperplasia group, and tumor-bearing lymph node model was established in another 18 rabbits as tumor group. For Gd-DTPA-enhanced MRI, T1WI and T2WI were performed on 9 animals of each model, and T1 WI was acquired 80 seconds after administration of Gd-DTPA. For USPIO-enhanced MRI, T1WI, T2WI and T2 ＊ WI were performed on another 9 animals of each model before and 24 hours after administration of USPIO. MRI images were analyzed and correlated with surgical specimens and pathological results. Results In the tumor group, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of Gd-DTPA-enhanced MRI were 62. 5%, 91.3%, 88.2%, 70. 0% and 76. 6%, respectively. The corresponding values of USPIO-enhanced MRI were 95.0%, 90. 9%, 90.5%, 95.2% and 92.9%, respectively. The sensitivity and accuracy of USPIO-enhanced MRI differ significantly from those of Gd-DTPA-enhanced MRI.In the hyperplasia group, the accuracy of Gd-DTPA-enhanced MRI was 74.2%, while 87.1% for USPIO-enhanced MRI. Conclusion USPIO-enhanced MRI has higher accuracy in diagnosing metastatic lymph nodes than Gd-DTPA-enhanced MRI.