较低级别星形细胞瘤治疗后MRI征象及预后:IDH表型的影响

The Influence of IDH Gene Phenotype on MRI Signs and Prognosis in Post-Treatment Lower Grade Astrocytoma

目的探讨异柠檬酸脱氢酶(IDH)不同表型的较低级别星形细胞瘤(LGA)治疗后MRI征象差异及其对生存的影响。方法回顾性分析经手术病理确诊并行IDH基因检测的49例LGA。观察IDH野生型与突变型LGA两组间临床因素[年龄、细胞增殖抗原标记物(Ki-67)、部位、WHO分级]及治疗后MRI征象[残腔壁强化类型、新增强化、新增室管膜下区受累(SVZ)、残腔外FLAIR高信号范围变化、残腔FLAIR相对信号强度]差异及其生存影响。采用受试者工作特征曲线评价不同因素及模型、IDH基因表型对于预测治疗后LGA的预后效能。结果 49例LGA包括IDH突变型26例、野生型23例。IDH野生型组WHO级别较高(P=0.035),O6-甲基鸟嘌呤-DNA甲基转移酶(MGMT)非甲基化状态者较多(P=0.043),残腔壁粗线及结节样强化较多(P=0.001),残腔外FLAIR高信号范围增大较明显(P=0.014),残腔FLAIR相对信号较高(P<0.001)。IDH突变型LGA的无进展生存(PFS)[957天(838~1077)]较野生型者[440天(333~546)]长(P<0.001);IDH突变型LGA的总生存期(OS)[1022天(931~1112)]较野生型者[764天(637~890)]长(P=0.003)。受试者工作特征曲线分析显示,联合IDH基因表型的综合模型(AUC=0.914)对于生存预后的预测效能优于WHO分级、常规MRI、IDH表型、WHO分级+常规MRI模型(AUC分别为0.698、0.896、0.742、0.900),敏感性达0.800、特异性0.941。结论 IDH表型影响LGA治疗后MRI征象及生存,其中野生型者更易出现残腔壁明显强化、残腔及其周围FLAIR高信号进展。IDH基因表型信息可改善临床影像模型预测LGA生存预后的能力。

Objective The study was aimed at exploring the MRI signs in post-treatment lower grade astrocytoma(LGA) with different isocitrate dehydrogenase(IDH) gene phenotype and analysing its effect on patients’ overall survival(OS). Methods The clinical variables and MRI signs of 49 LGA,with pathologically proven and IDH gene phenotype detected, were collected retrospectively.LGA were divided into IDH mutant-type and IDH wild-type groups, clinical factors(age, Ki-67,location, WHO grades) and post-treatment MRI signs(residual cavity wall enhancement, new remote enhancement, subventricular zone involvement, FLAIR area change outside residual cavity, and relative FLAIR of residual cavity) were observed and then we researched the effect of these factors on survival.Chi-square test, t test and Mann-Whitney U test were used to evaluate the factors;receiver operating characteristic curve(ROC) was used to evaluate different models and the diagnostic efficacy of IDH gene phenotype. Results IDH mutant-type group and IDH wild-type group had 26 and 23 cases, respectively.IDH wild-type group had higher WHO grades(P=0.035),Oxygen 6-methylguanine-DNA methyltransferase(MGMT) tended to non-methylated state(P=0.043),the enhancement of residual cavity wall tended to thick linear and nodular(P=0.001),FLAIR area change outside residual cavity was increased significantly(P=0.014),and relative FLAIR of residual cavity was higher(P=0.001).The PFS and OS of IDH mutant-type group was longer than IDH wild-type group(PFS:957 days vs 440 days;OS:1022 days vs 764 days).ROC analysis showed that model combined IDH gene phenotype, with AUC was 0.914,sensitivity was 0.800,specificity was 0.941,was more effective than clinical model, MRI model, IDH model, and clinical and MRI combined model in predicting prognosis(AUC were 0.698,0.896,0.742,0.900,respectively). Conclusion IDH gene phenotype effected MRI signs in post-treatment LGA,residual cavity wall tended to thick linear and nodular enhancement, FLAIR area change outside residual cavity increased significantly, relative FLAIR of residual cavity was higher in IDH wild-type post-treatment LGA.Model combined IDH gene phenotype could improve the diagnosis efficacy of survival prognosis.