扩散张量各向异性分数在星形细胞瘤中的诊断价值

目的评价MR扩散张量成像(DTI)各向异性分数(FA)在星形细胞瘤中的应用价值.方法经手术及病理证实的星形细胞瘤共26例,其中低级别星形细胞瘤10例,高级别星形细胞瘤16例.行常规MR 、DTI检查.构建 FA 图,并测量肿瘤、水肿区及正常白质的FA值.结果正常白质纤维在FA图上表现为高信号.低级别星形细胞瘤多呈低信号,边缘清晰,周围白质纤维呈高信号,信号未见明显减低. 高级别星形细胞瘤亦多呈低信号,边缘模糊,肿瘤实体区与水肿区FA值无显著性差异(P＞0.05);所有病例肿瘤实体区和水肿区 FA值与邻近正常脑白质进行比较,存在显著性差异(P＜0.05),即FA图不能明确区分肿瘤边缘及水肿区,但能将二者和正常白质纤维束鉴别.结论 DTI可清楚显示肿瘤与周围白质纤维的解剖关系,指导临床制定手术方案.

Fractional anisotropy map of diffusion tensor imaging in astrocytoma

Objective To evaluate clinical value of diffusion tensor imaging (DTI) and fractional anisotropy (FA) map in astrocytoma. Methods Twenty-six patients with histologically confirmed astrocytoma (10 low-grade and 16 high-grade astrocytoma) underwent conventional MRI and DTI. FA value and map was calculated in the area of tumor, edema and normal white matter. Results The normal white matter tract was shown as hyperintensity signal on FA map, but not clearly seen on conventional MR images. As for low-grade astrocytoma, the tumors mostly displayed as hypointensity signal with clear margin on FA map, the white matter tract surrounded the tumors showed as hyperintensity signal, no disruption could be seen. As for high-grade astrocytoma, the tumors mostly demonstrated as hypointensity signal with unclear margin on FA map. There were no significantly difference of FA value between tumors and edematous brain on FA map. FA was significantly different in tumor and edema from normal white matter in all cases. It means that FA map can distinguish tumor and edema from normal white matter, but can not distinguish tumor from edema. Conclusion DTI can demonstrate clearly the detailed relationship between tumor and nearby white matter tract and was found to be beneficial to the surgical planning for brain tumor resection.