3．0T弥散张量成像FA值和ADC值在颅脑恶性星形细胞瘤中的运用

目的：探讨磁共振弥散张量成像FA值和ADC值在颅脑恶性星形细胞瘤中的应用价值。方法：收集经手术及组织病理学证实的恶性星形细胞瘤患者14例，术前行常规MRI平扫、DTI检查、增强扫描及1H-MRS检查，工作站自动生成各向异性指数图（FA图）及表观弥散系数图（ADC图），定义肿瘤实质区为最高Cho／Cr和Cho／NAA比值、异常强化、T2WI信号异常区；定义瘤体边缘为Cho／Cr和Cho／NAA比值异常、无强化、T2WI信号异常区；定义瘤周水肿区为正常MRS表现、无强化、T2WI信号异常区；定义正常白质区为正常MRS表现、无强化、T2WI信号正常区（肿瘤同侧或对侧）；分别测量上述区域的FA1—4值、ADC1—4值，分析比较上述4个区FA值、ADC值有无统计学差异。结果：肿瘤实质区、瘤体边缘、瘤周水肿区及正常白质区平均FA值为FA1：0．1822±0．0583，FA2：0．2947±0．0786，FA3：0．1769±0．0942，FA4：0．6668±0．0817。肿瘤实质区、瘤体边缘、瘤周水肿区与正常自质区比较差异有高度显著性（P=0．000），瘤体边缘与肿瘤实质区、瘤周水肿区之间差异有高度显著性（P〈0．005），肿瘤实质区与瘤周水肿区差异无显著性（P〉0．05）；平均ADC值为ADC1：11．132±4．101，ADC2：11．175±2．983，ADCB：14．939±2．857，ADCA：7．265±0．914（单位10^-3mm^2／s）。瘤体实质部、肿瘤边缘及瘤周水肿区与正常脑白质区ADC值差异有高度显著性（P〈0．005）；瘤体实质部、肿瘤边缘与瘤周水肿区差异有高度显著性（P〈0．005）；而瘤体实质部与肿瘤边缘差异无显著性（P〉0．05）。结论：FA值和ADC值对高级别星形细胞瘤浸润范围的划定有重要价值。

The study of FA and ADC values by diffusion tensor imaging at 3.0T on malignant cerebral astrocytoma

Objectlve：To investigate the value of FA and ADC values of diffusion tensor MR imaging on malignant cerebral astrocytoma. Methods： 14 patients with malignant cerebral astrecytoma proved by surgery and pathology underwent MPd plain and contrast-enhanced scanning, diffusion tensor MR imaging and 1 H-MILS before operation. We defined tumor center as an area containing the highest chollne/creatine and choline/N-actetyl aspartate ratios, contrast enhancement, and abnormal T2 signal intensity. Tumor border was defined as tissue with abnormal Cho/Cr and Cho/NAA ratios, no enhancement, and high T2 signal intensity. Peritumoral edema area was defined as tissue with normal MRS, no enhancement, and high T2 signal intensity. Normal white matter was assumed if tissue had normal proton MR spectra, no enhancement, and normal T2 signal intensity in the hemispheres ipsilateral or contralateral to tumor. FA and ADC maps were calculated and regions of interest were manually placed over areas of tumor center, tumor border, peritumoral edema, and normal tissue. The values of FA and ADC in 4 regions narrated above were measured as FA1-4 and ADC1-4,respectively. Comparisons were made by analysis of variance.Results： The average FA values of tumor center, tumor border, peritumoral edema,and normal white matter were FA1：0.1822 ±0.0583,FA2：0.2947 ± 0.0786, FA3：0.1769 ± 0.0942, FA4：0.6668 ± 0.0817. There were significant differences between FA1-3 and FA4（ P = 0.000）, and between FA2 and FA1, FA3 （ P 〈 0.005）, whereas there were no significant differences between FA1 and FA3（ P 〉 0.05）. The average ADC values of tumor center, tumor border, pedtumoral edema, and
normal white matter were ADC1：11.132± 4.101, ADC2：1l. 175± 2.983, ADC3：14.939 ± 2.857, ADC4：7.265 ± 0.914（10-3mm^2/s）. There were significant differences between ADC1-3 and ADCA（ P 〈 0.005）, and between ADC1, ADC2and ADC3（ P 〈 0.005）, while, there were no significant between ADC1 and ADC1（ P 〉 0.05）. Concluslon：T