摘要目的 探讨表观弥散系数值(ADC)与部分各向异性值(FA)在脑星形胶质细胞瘤研究中的价值.方法 对33例经病理证实的脑星形胶质细胞瘤患者进行MR常规检查、弥散加权成像(DWI)检查与弥散张量成像(DTI)检查.测定并比较肿瘤不同组成区域及不同级别肿瘤的ADC值、FA值.结果 肿瘤实质区、肿瘤坏死区、瘤周水肿区及对侧正常脑组织的ADC值分别为1.28±0.44,1.97+-0.53,1.74±0.47,0.80±0.18,FA值分别为0.18±0.07,0.14±0.05,0.16±0.05,0.58±0.10,肿瘤组织与正常组织的ADC值差异有统计学意义(均P<0.05),两者的FA值差异有统计学意义(均P<0.05).肿瘤组织组成区域(肿瘤实质、肿瘤坏死、瘤周水肿)之间的FA值差异无统计学意义,肿瘤实质与肿瘤坏死、瘤周水肿的ADC值差异有统计学意义(P<0.05).结论 ADC值在鉴别肿瘤成分、肿瘤边界方面有重要价值,对于肿瘤的分级有一定的作用;FA值在肿瘤分界方面有重要价值,对高级别与低级别肿瘤的鉴别有一定价值.

abstractsObjective To evaluate the value of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in identification of tumor element and grading of brain astrocytoma.Methods Thirty-three patients with histologically confirmed aatrocytoma underwent diffusion weighted imaging(DWI), diffusion tensor imaging(DTI), and conventional MRI before operation.The values of ADC and FA of different regions in the same tumor and of astrocytoma of different grades were measured and compared.Results The ADC values of the tumor parenchyma, necrotic region, peritumoral edema region were (1.28 ± 0.44),(1.97 ± 0.53), and(1.74 ± 0.47) respectively, all significantly higher than that of the corresponding normal brain tissues [(0.80 ± 0.18), P = 0.009, P = 0.000, P = 0.000 ] with significantly differences between the tumor parenchyma and necrotic region and peritumoral edema region(both P < 0.05), however, there was not significant difference between the necrotic region and peritumoral edema region.The FA values of the tumor parenchyma, necrotic region, and peritumoral edema region were(0.18 ± 0.07), (0.14 ± 0.05), and (0.16 ± 0.05) respectively, all significantly higher than that of the corresponding normal brain tissues [(0.58 ±0.10), all P =0.000], without significant differences among the former 3 groups.There were no significant differences in the ADC and FA values among the tumors at different grades, however, there was a tendency of ADC to decrease and of FA to increase along the increase of grade of tumor, although not significantly.Conclusion ADC value plays an important part in distinguishing tumor components and determining tumor boundary, and plays a certain role in judging the grade of astrocytomas.FA value is vital to determine the tumor boundary, and has certain value in differentiating high-grade from low-grade astrocytomas.