脑胶质瘤术后放疗后复发和放射性脑坏死磁共振弥散张量成像鉴别

Distinction between brain glioma recurrence and radiation necrosis after postoperative radiotherapy using MR diffusion tensor imaging

目的:评价磁共振弥散张量成像(DTI)对胶质瘤术后放疗后复发和放射性脑坏死的鉴别价值。方法:对35例脑胶质瘤术后放疗后疑似肿瘤复发者行常规MRI和DTI检查。在表观弥散系数(ADC)图及各相异性分数(FA)图上对应病变强化区、水肿区和对侧半球正常脑白质区(对照)选择感兴趣区,测量ADC值和FA值,计算病变强化区和水肿区标准化ADC比值和FA比值,行受试者工作特征(ROC)曲线分析。结果:经组织学检查及胶质瘤术后随访,确定胶质瘤复发20例、放射性脑坏死15例。肿瘤复发组病变强化区ADC比值(1.34±0.15)低于放射性脑坏死组(1.62±0.17)(t=5.162,P<0.001),FA比值(0.45±0.03)高于放射性脑坏死组(0.32±0.03)(t=12.686,P<0.001)。2组水肿区以上2指标差异无统计学意义。ROC曲线分析结果显示,以病变强化区ADC比值<1.65和(或)FA比值>0.36判断肿瘤复发时,DTI的诊断敏感性、特异性和准确性分别为85.0%(17/20)、86.7%(13/15)和85.7%(30/35)。结论:DTI对鉴别胶质瘤术后放疗后复发和放射性脑坏死有重要的应用价值。

Aim ： To evaluate the value of MR diffusion tensor imaging（DTI） to distinguish brain glioma recurrent from radiation necrosis after postoperative radiotherapy. Methods： Thirty-five patients of brain glioma （20 true, 15 false） were examined by conventional MRI and DTI. Regions of interest （ROI） were manually drawn in the regions of contrast-enhancing lesion, close edema and the contra-lateral semi-sphere corresponding normal white matter on the ADC and FA maps, respectively. ADC and FA values of ROI were measured. Then the standardized ADC and FA ra- tios were calculated. The receiver operating characteristic curves were analyzed. Results： The mean ADC ratio （1.34 ± 0.15 ） in the contrast-enhancing lesions was significantly lower in patients with tumor recurrence compared with those with radiation necrosis （1. 62 ± O. 17 ） （t = 5. 162 ,P 〈 O. 001 ）. The mean FA ratio（0.45 ± 0.03 ）in the eontrast-enhaneing lesions was significantly higher in patients with tumor recurrence compared with those with radiation necrosis （0.32 ± O. 03 ） （t = 12. 686, P 〈 0.001 ）. Neither the mean ADC nor FA ratio in edema had statistical difference between the two groups. Tumor recurrence was suggested when either ADC ratio 〈 1.65 or/and FA ratio 〉 O. 36 according to ROC curve analysis of contrast-enhancing lesions, and the diagnostic sensitivity, specificity and ac- curacy for recurrent tumor of DTI were 85.0% , 86.7 % and 85.7%. Conclusion ： MR DTI examination is valuable to distinguish brain glioma recurrence from radiation necrosis.