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目的评价近似弥散系数(ADC)值、张量D值(trace D)值及各向异性分数(FA)值在鉴别星形细胞肿瘤实质、瘤周水肿及正常组织中的作用以及评估星形细胞肿瘤良恶性的价值。方法采用GE 1.5T MR仪,对23例1~2级星形细胞肿瘤及22例3~4级星形细胞肿瘤进行了常规磁共振成像(MRI)、弥散加权成像(DWI)及弥散张量(DTI)成像,弥散敏感系数(b值,b=os/mm2及b=1000s/mm2)测量病变感兴趣区的数值。结果1~2级星形细胞肿瘤实质的最低ADC值(1.46±0.32)×10-3mm2/s和trace D值(0.64±0.19)×10-3mm2/s,明显高于3~4级ADC值(0.87±0.18)×10-3mm2/s和(0.48±0.15)×10-3mm2/s,(P<0.01)。低度恶性肿瘤肿瘤实质与瘤周水肿之间ADC值无显著性差异;高度恶性肿瘤肿瘤实质与瘤周水肿间有显著性差异。FA图像可清楚显示肿瘤与白质纤维的关系。结论结合常规MRI,ADC值及trace D值有助于鉴别星形细胞肿瘤良恶性。
Objective To evaluate the value of approximate diffusion coefficient (ADC) value, trace D value and anisotropy fraction (FA) value in differentiating astrocytic tumor from peritumoral edema and normal tissues and to evaluate the effect of astrocyte The value of benign and malignant tumors. Methods The GE 1.5T MR instrument was used to evaluate the magnetic resonance imaging (MRI), diffusion weighted imaging (DWI), and diffusion tensor of 23 grade 1 ~ 2 astrocytic tumors and 22 grade 3 ~ 4 astrocytic tumors (DTI) imaging, diffusion-sensitive coefficient (b value, b = os / mm2 and b = 1000s / mm2) Results The minimum ADC values (1.46 ± 0.32) × 10-3mm2 / s and trace D (0.64 ± 0.19) × 10-3mm2 / s in astrocytoma grade 1 ~ 2 were significantly higher than those in grade 3 ~ 4 ADC (0.87 ± 0.18) × 10-3mm2 / s and (0.48 ± 0.15) × 10-3mm2 / s, respectively (P <0.01). There was no significant difference in ADC value between low grade tumor and peritumoral edema. There was significant difference between high grade tumor and peritumoral edema. FA images clearly show the relationship between tumor and white matter fibers. Conclusion Combined with conventional MRI, ADC value and trace D value can help identify astrocytomas.