不同b值对瘤体及瘤周水肿扩散加权成像的影响

Effect of different b-values in tumor and peritumoral edema on diffusion weighted imaging

目的:探讨不同b值对高级别胶质瘤瘤体及瘤周水肿扩散加权成像(DWI)的影响。方法:25例高级别胶质瘤患者行3种b值DWI检查,比较兴趣区域信号值(SI)、表观扩散系数(ADC)与b值的关系。结果;随着b值的升高,各兴趣区SI、ADC值均降低,SI值在瘤周区域下降最多,ADC值在瘤体区域下降最多。不同b值时瘤体的ADC值与SI值与瘤周差异均有统计学意义(P<0.05)。b值3000s/mm2时SI、ADC值对瘤体、瘤周鉴别能力最佳,曲线下面积分别为0.90,0.93,敏感度、特异度、阳性预测值、阴性预测值分别为88.0%,80.0%,81.5%,87.0%及96.0%,84.0%,87.5%,84.6%。结论:b值为3000s/mm2时对高级别胶质瘤瘤体、瘤周鉴别能力最佳,此结论尚需进一步大样本研究证实。

Objective：To investigate the effect of different b values in high grade glioma and peritumoral edema on diffusion weighted imaging（DWI）.Methods：Twenty-five patients with high grade glioma underwent DWI,three different bvalues were applied.The signal intensity（SI）and apparent diffusion coefficients（ADC）values in regions of interests（tumor and peritumoral edema）were measured and compared.Results：The SI and ADC values in all regions of interest decreased with the increasing of b-value.The most significant declination of SI was in regions of peritumoral edema while the ADC value declined most significantly in regions of tumor.The SI and ADC values in the regions of tumor was significantly different from that in the region of peritumoral edema with three different b-values（P〈0.05）.The capability of SI and ADC value in differentiating tumor from peritumoral edema was optimal as b-value was 3000s/mm^2.The area under the curve was 0.91,0.93,respectively.The sensitivity,specificity,positive predictive value,negative predictive value were88.0%,80.0%,81.5%,87.0% and 96.0%,84.0%,87.5%,84.6%,respectively.Conclusion：The optimal b-value in differentiating tumor from peritumoral edema was 3000s/mm^2.This conclusion needs to be further evaluated by a large sample study.