SPIO与Gd剂增强MRI对转移性淋巴结诊断的实验研究

摘要

目的:比较SPIO与Gd-DTPA 2种增强MRI方法对淋巴结转移瘤的诊断效果.方法:①将24只新西兰大白兔随机分为2组,每组12只.第1组于后肢股四头肌内种植VX2肿瘤,建立兔腘窝转移性淋巴结模型;第2组于后肢股四头肌内注射蛋黄乳清液,建立兔腘窝反应增生性淋巴结.②MRI扫描,包括平扫、SPIO及Gd-DTPA增强.序列包括T1WI,T2WI,PDWI,GRE T2*WI.③2位影像诊断医师进行盲诊,并与病理结果对照.④进行统计学分析.结果:SPIO增强,第1组大部分淋巴结信号较平扫未见明显变化,个别淋巴结在T2WI、PDWI及GRE T2*WI序列出现斑片状低信号影;第2组淋巴结在各序列均为低信号.Gd-DTPA增强扫描,2组淋巴结出现均匀或不均匀强化.SPIO增强扫描敏感度和特异度分别为83.3%,83.3%;Gd-DTPA增强扫描敏感度和特异度分别为58.3%,66.7%.SPIO增强扫描阳性预测值及阴性预测值分别83.3%,83.3%;Gd-DTPA增强扫描阳性预测值及阴性预测值分别为63.6%,61.5%.SPIO增强扫描K=0.667,P=0.01;Gd-DTPA增强扫描K=0.25,P=0.219;2组K=0.250,P=0.219.2种方法ROC曲线下面积分别为0.833,0.625,P值分别为0.006,0.299.结论:SPIO是一种新型MRI对比剂,与Gd-DTPA相比,对转移性淋巴结与炎症反应增生性淋巴结的鉴别诊断具有较高特异性及敏感性.%Objective: To compare SPIO with Gd-DTPA enhanced MRI methods in diagnosis of metastatic lymph node .Methods :①24 New Zealand white rabbits were randomly divided into two groups. The first group was established metastatic lymph node model by administration VX2 tumor cell in rabbit hindlimb muscles. The second group was established the reactive hyper-plastic lymph node model by injection liquid egg yolk in rabbit hindlimb muscles. ②MRI protocols involved non-enhanced scan, SPIO contrast enhanced scan and Gd-DTPA contrast enhanced scan ,with T1 WI,T2WI,PDWI,GRE T2 * WI sequences. ③All images were evaluated by two senior physicians. ④Statistical analysis was performed. Results:For the SPIO contrast enhanced scan ,the signal intensity of most lymph nodes of the first group didn 't change significantly ,while few lymph node showed small patchy hypo-intensity in some sequences. All the lymph nodes showed large patchy hypo-intensity in all sequences of the second group. For Gd-DTPA contrast enhanced scan ,all lymph nodes were enhanced. The sensitivity and specificity of SPIO examina-tion(83. 3% ,83. 3% )were higher than that of Gd-DTPA examination(58. 3% ,66. 7% ). The Positive predictive value and negative predictive value of SPIO examination (83. 3% ,83. 3% )were higher than that of Gd-DTPA examination(63. 6% ,61. 5% ). By Comparison with pathological examination ,the Kappa value of SPIO examination was 0. 667( P = 0. 01<0. 05),and the Kappa value of Gd-DTPA examination was 0. 25( P=0. 219>0. 05). The Kappa value of the two enhanced examinations was 0. 250 ( P =0. 219>0. 05). The area under the ROC curve of SPIO and Gd-DTPA contrast enhanced scan were 0. 833 and 0. 625 .respectively. Conclusion:SPIO is a new MRI contrast agent. It has higher specificity and sensitivity in differential diagnose of lymph nodes than Gd-DTPA contrast enhanced scan.