高级别星形细胞瘤扩散张量成像应用研究

Diffusion Tensor Imaging of High-Grade Astrocytomas

目的 :研究平均扩散系数 (ADC)和各向异性分数 (FA)在鉴别高级别星形细胞瘤肿瘤组织、水肿及正常脑组织中的价值。方法 :16例高级别星形细胞瘤在治疗前行常规MRI及扩散张量成像 (DTI)。在T1WI增强、T2 WI及FA图上确定肿瘤、水肿及邻近正常白质区 ,测量并分析这些区域FA值及ADC值的差异。结果 :在ADC图上 ,肿瘤实体区与正常脑实质相比 ,几乎呈等信号 ;水肿区呈稍高信号 ;肿瘤囊变坏死区呈高信号。在FA图上 ,囊变坏死区呈低信号 ;肿瘤区呈等信号及低信号 ;水肿区呈等信号及稍高信号。肿瘤囊变坏死区ADC值 (2 .16± 0 .14 7)× 10 -3 mm2 /s ,水肿区 (1.5 5± 0 .0 66)× 10 -3 mm2 /s ,肿瘤实体区 (1.3 3± 0 .0 8)× 10 -3 mm2 /s ,邻近正常白质区 (0 .76± 0 .0 5 7)× 10 -3 mm2 /s。邻近正常白质区FA值最高 (0 .45± 0 .0 3 7) ,肿瘤囊变坏死区最低 (0 .0 5± 0 .0 12 )。所有患者肿瘤实体区与水肿区、正常白质区ADC值的差别均具有显著性意义 (P <0 .0 5 )。所有患者肿瘤实体区、水肿区与正常白质区FA值差异有显著性意义 (P <0 .0 5 ) ,肿瘤实体区与水肿区FA值差异无显著性意义 (P >0 .0 5 )。结论 :ADC值可用于区分正常脑白质、水肿和肿瘤实体区 ,FA值对于组织学鉴别无明显意义。ADC值。

Objective:To evaluate the usefulness of FA and ADC in differentiating tumor,edema area,and normal white matter.Methods:16 patients with pathological grade Ⅲ～Ⅳ astrocytomas underwent conventional MR and DTI before therapy.Tumor,edema and apparent normal white matter regions of brain were determined on T 2WI and contrast-enhanced T 1WI images.Apparent diffusion coefficients (ADC) value and fractional anisotropy (FA) value were calculated in areas of tumor,edema,and normal brain.Comparisons were made by analysis of each variance.Results:On ADC map,the tumors were almost isointense compared with the normal brain,and the edematous brain was slightly hyperintense than the normal brain;necrotic tumor core showed high signal.On FA map,the necrotic tumor core appeared hypointense,the tumor appeared isointense or hypointense,the edematous brain appeared isointense or slightly hyperintense.The ADC value was the highest in the necrotic tumor core(2.16±0.147)×10 -3 mm 2/s,followed by edematous brain(1.55 ±0.066)×10 -3 mm 2/s,enhancing tumor tissue(1.33 ±0.08)×10 -3 mm 2/s,and normal white matter (0.76±0.057)×10 -3 mm 2/s.FA was the lowest in the necrotic core (0.05±0.012) and was the highest in normal white matter (0.45±0.037).ADC was significantly different in enhancing tumor,necrotic tumor core,edematous and normal white matter in all patients.FA was significantly different in tumor solid area,necrotic tumor core and normal white matter in all cases.There was no significant difference of FA value between tumor and edematous brain on FA map.Conclusion:ADC value can help to distinguish tumor from adjacent edema,necrotic tumor core and normal white matter.FA value added no benefit to differentiation diagnosis.Further study are needed to confirm whether ADC value and FA value can be used to differentiate tumor invasion.