MRI信号强度比在脑恶性肿瘤鉴别诊断及Ki-67表达的应用价值

Application value of MRI in the differential diagnosis and expression of Ki-67 in brain malignant tumors

目的探讨常规MRI信号强度比(SIR)在鉴别诊断胶质母细胞瘤(GBM)与原发性中枢神经系统淋巴瘤(PCNSL)的应用价值及与Ki-67表达的相关性。方法回顾性分析本院72例GBM和32例PCNSL MRI资料,应用t检验分析肿瘤SIR,包括T1WI信号比(rT1)、T2WI信号强度比(rT2)、T1WI增强信号比(rT1CE)及T2WI/T1WI信号比(T2/T1)四个指标,并通过受试者工作特征(ROC)曲线评估单个及联合指标的鉴别诊断性能,Spearman检验分析SIR与Ki-67标记指数(Ki-67 LI)的相关性。结果GBM rT1和rT1CE(rT1:0.482±0.117,rT1CE:1.319±0.243)明显低于PCNSL(rT1:0.557±0.478,rT1CE:1.594±0.156),而rT2及T2/T1(rT2:1.814±0.285,T2/T1:3.995±1.189)明显高于PCNSL(rT2:1.435±0.135,T2/T1:2.600±0.354),两组之间比较差异均具有统计学意义(P<0.001);ROC曲线分析rT1、rT2、rT1CE和T2/T1可用于鉴别GBM与PCNSL,其中单个参数时,T2/T1诊断效能最好(AUC:0.877),其敏感度93.8%,特异度76.4%,多个参数联合后,rT1+rT1CE+rT2+T2/T1鉴别诊断效能最高(AUC:0.966),敏感度和特异度分别为87.5%、91.7%。相关分析显示rT1和rT1CE与Ki-67 LI呈正相关,相关系数分别为0.301、0.399,rT2、T2/T1与Ki-67 LI呈负相关,相关系数分别为-0.428、-0.459。结论MRI肿瘤信号强度比对于GBM与PCNSL的鉴别诊断具有重要意义,其信号强度比作为定量参数,可为主观判断提供重要补充,并可初步评估肿瘤细胞增殖水平。

Objective To investigate the application value of conventional MRI signal intensity ratio(SIR)in differential diagnosis of glioblastoma(GBM)and primary central nervous system lymphoma(PCNSL)and the correlation with Ki-67 expression.Methods Retrospective analysis of 72 cases of GBM and 32 cases of PCNSL MRI data,t test were used to analyze signal intensity ratio of tumors,four indexes were included:signal ratio of T1WI(rT1),signal intensity ratio of T2WI(rT2),enhanced signal ratio of T1WI(rT1CE)and signal ratio of T2WI/T1WI(T2/T1).The differential diagnostic performance was evaluated by receiver operating characteristic(ROC)curve.Spearman test was used to analyze the correlation between SIR and(Ki-67 label index,Ki-67 LI).Results The rT1 and rT1CE(rT1:0.482±0.117,rT1CE:1.319±0.243)of GBM were significantly lower than that of PCNSL(rT1:0.557±0.478,rT1CE:1.594±0.156),while rT2 and T2/T1(rT2:1.814±0.285,T2/T1:3.995±1.189)were significantly higher than that of PCNSL(rT2:1.435±0.135,T2/T1:2.600±0.354),the comparison between the two groups was statistically significant(P<0.001).ROC curve analysis showed that rT1,rT2,rT1CE and T2/T1 could be used to distinguish GBM from PCNSL.A single parameter of T2/T1 had the best diagnostic efficacy(AUC:0.877),with a sensitivity of 93.8%and a specificity of 76.4%.rT1+rT1CE+rT2+T2/T1 combined parameters had the highest differential diagnostic efficiency(AUC:0.966),with sensitivity of 87.5%and specificity of 91.7%.Correlation analysis showed that rT1 and rT1CE were positively correlated with Ki-67 LI,the correlation coefficients were 0.301 and 0.399,while rT2 and T2/T1 were negatively correlated with Ki-67 LI,and the correlation coefficients were-0.428 and-0.459 respectively.Conclusion Tumor SIR in MRI is important for discriminating GBM from PCNSL,and SIR as a quantitative parameter can provide an important complement to subjective judgment and preliminarily evaluation for the proliferation level of tumor cells.