摘要
目的:探讨MRI弥散张量成像(DTI)显示脑白质纤维束在脑胶质瘤外科的意义。方法:2003年9月至2004年12月,30例脑内肿瘤患者接受术前常规头颅MRI序列检查的同时,进行DTI序列扫描,经后处理得到各向异性分数(FA)图显示脑白质纤维束结构,并进行FA值、图像信号强度及对比度的分析研究。结果:所有病例均成功实现包括DTI序列扫描以及FA图像生成。脑白质纤维束显示为显著的高信号结构;灰质显示为等信号;脑脊液显示为低信号;脑内肿瘤呈类圆形等、低信号灶;肿瘤周围间质水肿区白质纤维束仍能在DTI的FA图上显像。DTI的FA图像对于脑白质纤维束显影的信号对比度明显优于常规的T1W图像。结论:DTI影像可以清晰显示脑白质纤维束的形态结构。结合其他序列的MRI应用于脑胶质瘤的术前诊断,可以准确判别肿瘤和周围脑白质纤维束的毗邻关系,对脑胶质瘤手术方案设计以及术后神经功能障碍的预测与预防具有重要意义。
To assess the role of diffusion tensor imaging （DTI） of white matter tracts in cerebral gliomas surgery. Methods： Diffusion tensor images were obtained in 30 patients with cerebral gliomas, meanwhile the routing T 1-weighted （TIW）, T2-weighted （T2W）, contrast-enhanced T1W imaging, FLAIR imaging and diffusion tensor of the brain were acquired. Diffusion tensor images were obtained in axial sections covering the entire brain volume with the following parameters： single-shot spin-echo echoplanar imaging （SE EPI） sequence, TR/TE=10 000/112 ms, section thickness=5 mm, section space=0 mm, Matrix size=128 ×128, field of view=220 × 220 mm, NEX=1. The number of diffusion encoding directions for each slice was 25. And total 19 slices were acquired for the complete coverage of the cerebra. For each pixel, postprocessing was completed to compute the fractional anisotropy （FA） of diffusivity and then FA maps were acquired for b factors=5 and 1 000 s/mm^2. FA maps were used to visualize the anatomy of white matter fiber tracts. The FA values were studied to compare the diffusion tensor coefficient in different anatomical structure. The signal intensity in each similar couple ROIs of both T1W and DTI images was measured, and then relative intensity value （white matter/grey matter） were calculated to assess the image contrast respectively. Results： A complete set of detailed white matter fiber anatomy maps of the brain by means of FA maps of DTI at high resolution was obtained. At visual inspection of FA maps, the white matter tracts appeared as strongly hyperintense signal, while the grey matter presented an isointense area in contrast to the strongly hypointense signal of the CSF. Glioma boundaries were less sharper than on contrast-enhanced T1W images, but delineation could still be easily seen as hypointense lesion on FA map. The principal fiber tracts were well observed in all cases, including the tracts nearby the lesions. Conclusion. The FA map of DTI offered the optimal visualization of white matter tracts. The combination of the DTI and other conventional MRI, in the diagnosis of cerebral gliomas and surgery decision-making were valuable in presenting the topographical character of involving white matter tracts and relationship with the margins of neighboring tumors. It should be of great value in the surgical planning as well as estimation and reduction of potential postoperative neurological deficits for the cerebral gliomas resection.
出处
《中国临床神经科学》
2007年第3期253-259,共7页
Chinese Journal of Clinical Neurosciences
关键词
核磁共振成像
弥散张量成像
脑
胶质瘤
magnetic resonance imaging diffusion tensor brain glioma
