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目的评价高b值MR扩散加权成像(diffusion weighted imaging,DWI)对胶质瘤分级的应用价值。资料与方法经手术病理证实的36例胶质瘤(高级23例,低级13例)患者行常规MRI和DWI检查,分析其DWI表现。测量低、中、高b值(b=600 s/mm2、1000 s/mm2、3000 s/mm2)DWI图像中不同级别胶质瘤的肿瘤实性区域与对侧相应部位正常脑白质区的信号强度(SI)和表观扩散系数(ADC)值,计算肿瘤与正常区SI的比值即相对信号强度(rSI)和ADC的比值即相对ADC值(rADC)。结果 (1)在高b值时,21例(91.3%)高级胶质瘤呈高信号,而12例(92.3%)低级胶质瘤呈低信号。(2)在b值相同时,高级胶质瘤的平均rSI明显高于低级胶质瘤,平均ADC值、平均rADC值明显低于低级胶质瘤,两组之间的差异均有统计学意义(P<0.0001),其中rSI以及rADC的差异在高b值时更大。(3)对于高级胶质瘤,在高b值与中b值、高b值与低b值比较时平均rSI值以及平均rADC值的差异均有统计学意义(P<0.0001);对于低级胶质瘤,在高b值与中b值、高b值与低b值比较时平均rSI的差异均有统计学意义(P<0.0001)。结论高b值DWI较中、低b值DWI对胶质瘤分级更有价值。
Objective To evaluate the value of diffusion weighted imaging (DWI) with high b value in glioma grading. Materials and Methods 36 cases of gliomas (23 cases of advanced grade and 13 cases of lower grade) proved by pathology were examined by routine MRI and DWI to analyze their DWI manifestations. The signals of the tumor-specific areas of different grades of gliomas in the low, middle and high b values (b = 600 s / mm2, 1000 s / mm2, 3000 s / mm2) DWI images and normal white matter regions of the corresponding contralateral counterparts were measured The ratio of relative signal intensity (rSI) to ADC, ie, the relative ADC value (rADC), was calculated as the ratio of tumor to normal SI. Results (1) In high b value, 21 cases (91.3%) of high grade gliomas showed high signal, while 12 cases (92.3%) of low grade gliomas showed low signal. (2) The average rSI of high grade glioma was significantly higher than that of low grade glioma at the same value of b, the average ADC value and mean rADC were significantly lower than that of low grade glioma, the difference between the two groups was statistically significant (P <0.0001), with differences in rSI and rADC being greater at high b values. (3) For high grade gliomas, the average rSI values and mean rADC values were significantly different between high b value and middle b value, high b value and low b value (P <0.0001) The differences of mean rSI between high b value and middle b value, high b value and low b value were statistically significant (P <0.0001). Conclusion High b-value DWI is more valuable than glioma grade in medium and low b value DWI.