MRI灌注和扩散加权成像对脑胶质瘤分级的比较研究

Comparative Study of MRI Perfusion-weighted Imaging and Diffusion-weighted Imaging in Grading of Glioma

【目的】分析同一组脑胶质瘤的MRI灌注和扩散加权图像信息,对比这两种功能成像对脑胶质瘤病理分级的诊断价值。【方法】42例(低级胶质瘤20例,高级胶质瘤22例)脑胶质瘤患者行MRI灌注及扩散加权成像,测量肿瘤实质的灌注参数和弥散参数,进行差异的t检验,采用受试者操作特征曲线(ROC曲线)确定找到诊断阈值,计算敏感性及特异性。对两种诊断方法进行评价并对诊断符合率进行χ2检验。【结果】低级胶质瘤20例,高级胶质瘤22例。低级胶质瘤的rCBV,rMSD,rMTT,ADC和rADC值分别为2.25±1.07,1.82±0.70,1.07±0.08,(1.36±0.14)×10-3mm·2s-1和1.69±0.23。高级胶质瘤的rCBV,rMTT,rMSD,ADC和rADC值分别为4.83±1.84,3.36±0.88,1.04±0.06,(1.10±0.12)×10-3mm2·s-1和1.41±0.18。高级与低级胶质瘤的rCBV,rMSD,ADC和rADC值有统计学意义。以rCBV值3.5为阈值,诊断敏感度为81.8%,特异度为90%;rMSD值2.1为阈值,诊断敏感度为95.5%,特异度为80%;ADC阈值为1.23×10-3mm2/s时,诊断敏感度为86.4%,特异度为85%。通过对AUC的计算和假设检验,发现PWI和DWI诊断准确度较高,差异无统计学意义。【结论】以PWI和DWI的rCBV值3.5、rMSD值2.1、ADC值1.23×10-3mm·2s-1为阈值时,均有利于鉴别胶质瘤级别。这些阈值对于评价胶质瘤的术前病理分级以及指导肿瘤的治疗和估计预后具有一定的价值。

【Objective】To evaluate the value of MRI perfusion-weighted imaging（PWI）and diffusion-weighted imaging（DWI） in the grading of glioma by comparing the related parameters.【Methods】A total of 42（22 high-grade gliomas,20 low-grade gliomas）patients verified glioma by pathology underwent DWI and dynamic contrasted-enhanced T2＊-weighted PWI.Relative cerebral blood volume（rCBV）,relative maximum slope of decrease（rMSD）,relative mean transit time（rMTT）,apparent diffusion coefficient（ADC）and ADC ratios（rADC）data of high-grade and low-grade gliomas were measured and their difference was analyzed with t-test.Receiver operating characteristic（ROC）analyses were performed to determine optimum thresholds for tumor grading and also to calculate the sensitivity and specificity for tumor grading.【Results】The rCBV,rMSD,rMTT,ADC,and rADC values of low-grade gliomas were 2.25±1.07,1.82±0.70,1.07±0.08,（1.36±0.14）×10-3 mm2·s-1,and 1.69±0.23,respectively.The rCBV,rMTT,rMSD,ADC,and rADC values of low-grade gliomas were 4.83±1.84,3.36±0.88,1.04± 0.06,（1.10±0.12）×10-3 mm·2s-1,and 1.41±0.18,respectively.The results of rCBV,rMSD,ADC and rADC were between low-and high-grade gliomas（P0.0001）,while there was no significant difference in rMTT.The threshold of rCBV,rMSD,and ADC value were 3.5,2.1,and 1.23×10-3 mm·2s-1 respectively,and the diagnosis sensibility were 81.8%,95.5%,and 86.4%,respectively,and the specificity were 90%,80%,and 85%respectively.Both PWI and DWI showed high diagnosis accuracy,between which had no significant difference.【Conclusion】The threshold values of rCBV,rMSD,and ADC,which are 3.5,2.1,and 1.23×10-3 mm·2s-1 respectively,are beneficial to differentiate high-and low-grade gliomas.Threshold values can be used in clinical setting to evaluate tumors preoperatively for histological grade and provide a means for treatment and prognosis.