神经胶质瘤磁敏感加权成像与灌注成像和病理分级对比研究

Analysis of Semi Quantitative Susceptibility Weighted Imaging and Dynamic Enhanced Perfusion in Gliomas Grading:Comparative Study of Pathological Results

目的评价高场磁敏感加权成像(susceptibility weighted imaging,SWI)在脑胶质瘤的术前分级中的价值,肿瘤磁敏感信号(intratumoral susceptibility signal intensity,ITSS)与动态磁敏感增强(dynamic susceptibility contrast,DSC)MR灌注成像中的相对最大脑血流容积(maximum relative cerebral blood volume,rCBVmax)的相关性。资料与方法 32例经病理证实的胶质瘤患者分别行术前SWI和动态增强MR灌注成像,按照2007版WHO中枢神经系统肿瘤分级标准将胶质瘤分成三组,分析相同层面的ITSS和rCBVmax,分别比较ITSS分级、rCBVmax值、病理级别之间的相关性,评价ITSS和rCBVmax在胶质瘤病理分级诊断中的价值。结果 ITSS在胶质瘤中表现不同的形态,可呈点状、条状,或点条状聚集成团、片状;多位于肿瘤内部靠近T1WI呈强化部分的内侧。ITSS在不同级别的胶质瘤中差异有统计学意义(P<0.0001)。ITSS分级与胶质瘤的病理分级明显相关(r=0.961,P<0.0001)。rCBVmax与ITSS级别之间显著相关(r=0.846,P<0.0001),但ITSS最为密集的部位往往并非rCBVmax所处的位置。ITSS对高级别胶质瘤的诊断敏感性为94.7%、特异性为84.6%、阳性预测值为90%和阴性预测值为91.7%。结论高场MR非对比增强SWI、rCBVmax、脑胶质瘤病理分级间有很高的相关性,SWI对脑胶质瘤的术前分级有重要的价值。

Objective To evaluate the value of high-field susceptibility weighted imaging（SWI） in glioma grading before surgery and the correlationship between intratumoral susceptibility signal intensity（ITSS） and maximum relative cerebral blood volume（rCBVmax）.Materials and Methods Thirty two patients with glioma received both SWI and DSC examination at 3T MR system.The patients were divided into 3 groups according to the histopathologic grading.The intratumoral susceptibility signal intensity（ITSS） was graded as 0-3 for semiquantitative analysis.Spearman correlation analysis were used to determine the correlation between ITSS,rCBVmax,and histopathologic grading.Receiver operating characteristic（ROC） curve analysis were performed to determine the diagnostic accuracy for glioma grading.Results On SWI,the conglomerated mixed with fine linear and dot like ITSSs were demonstrated in all gliomas.These ITSSs were usually located in the inner portion of tumors with rim enhancement showed on contrast T1 weighted images.Significant difference of ITSSs was found between different pathologic grading of gliomas（P0.0001,Wilcoxon signed-rank test）.There is significant correlation between ITSS and histopathologic grading（r=0.961,P0.0001）.Great difference of rCBVmax was found between low grade glioma and high grade glioma.Significant correlation was found between ITSS and rCBVmax（r=0.846,P0.0001）,but densely prominent ITSSs did not correspond with regions of visual rCBVmax.The sensitivity,specificity,positive predictive value,and negative predictive value of ITSS in the glioma grading were 94.7%,84.63%,90%,and 91.7% respectively.Conclusion High field SWI is useful in the preoperative assessment of the histopathologic grading of glioma,and ITSS shows significant correlation with the rCBVmax in the same tumor section.