动态对比增强MRI在鉴别胶质瘤复发及放射性脑损伤中的应用

目的分析动态对比增强MRI（DCE-MRI）在鉴别胶质瘤复发与放射性脑损伤中的作用。材料与方法应用Philips 3.0 T TX MR扫描机，对28例脑胶质瘤术后放疗后患者（随访中出现异常强化灶）行头部DCE扫描，采用FFE序列行多层采集，28例患者被二次手术病理或临床及影像随访证实为胶质瘤术后复发17例，放射性脑损伤11例。采用渗透分析软件，在对比剂强化区域及对侧正常脑组织回顾性画出感兴趣区，获得T1加权信号强度-时间曲线，基于双室血流动力学模型，产生三个脑血流动力学参数Ktrans、Ve和Kep。测量时参考增强图像，手动勾画感兴趣区，为了减少误差反复测量8～10次，取其平均值。采用秩和检验比较胶质瘤复发和放射性损伤两组间的DCE灌注参数，并作ROC曲线分析，明确各项指标在临床上对于胶质瘤复发诊断的优越性。结果 Ktrans、Ve、Kep在胶质瘤复发组和放射性损伤组及对侧脑组织间有统计学意义，Ktrans在胶质瘤复发组高于放射性坏死组（P〈0.01），且Ktrans界值高于0.12对胶质瘤复发的诊断显示出100%的敏感度和87%的特异度，ROC曲线下面积为0.974。Ve值在胶质瘤复发组高于放射性坏死组（P〈0.01），ROC曲线下面积为0.872。Kep值在鉴别胶质瘤复发组与放射性坏死组不具有统计学意义（P〈0.05）。结论 DCE-MRI可以用于鉴别胶质瘤复发与放射性脑损伤，Ktrans值及Ve值对二者鉴别具有重要的临床意义。

Differentiation between recurrent gliomas and radiation-induced brain injuries using DCE-MRI

Objective：To analysis whether hemodynamic parameters derived from dynamic contrast-enhanced （DCE） T1-weighted magnetic resonance imaging （MRI） can be used to distinguish recurrent gliomas from radiation-induced brain injury. Materials and Methods： Twenty eight patients who were being treated for glial neoplasms underwent conventional and DCE-MRI using a Philips 3.0 T scanner. Penetration analysis software can be applied to obtain T1-weighted signal intensity-time curves. The pharmacokinetic modelling was based on a two-compartment model that allows for the calculation of Ktrans （transfer constant between intravascular and extravascular, extracellular space）, Ve （extravascular, extracellular space）, kep （transfer constant from the extracellular, extravascular space into the plasma）, Regions of interest （ROIs） were drawn manually around the entire recurrence-suspected contrast enhanced region which was measured three times and then obtain average value. A deifnitive diagnosis was established at subseuent surgical resection （seventeen） or clinicoradiologic follow-up （eleven）. nonparametric test was uesd to determine whether there was a difference between glioma recurrence and radiation-induced brain injury. Results：The Ktrans, Ve, Kep values in the normal white matter were signiifcantly different than those in the radiation necrosis and recurrent gliomas （P＆lt;0.01）. The signiifcantly different hemodynamic parameters between the recurrent tumor lesions and theradiation-induced necrotic sites were Ktrans and Ve, which were signiifcantly higher in the recurrent glioma group than in the radiation necrosis group （P〈lt;0.01）. A Ktrans cutoff value higher than 0.12 showed 100%sensitivity and 87%speciifcity for detecting the recurrent gliomas, The area under the ROC curve of Ktrans is 0.974 （P〈lt;0.01） and Ve is 0.872 （P=0.01）. The kep values in recurrent tumors were not signiifcantly higher than those in radiation-induced necrotic lesions （P＆gt;0.05）. Conclusions：DCE-MRI can be used to identify glioma recurrence with radiation-induced brain injury, Ktrans value and Ve value have important clinical signiifcance.