【摘要】 目的获取正常人脑组织磁共振扩散张量图像,评价不同b值条件下的扩散张量图像改变。方法筛选28例正常(常规MR显示未见异常者)健康成年人,分别选取b=1000s/mm2,b=2000s/mm2和b=3000s/mm2同时进行磁共振扩散张量成像(DTI),应用Philips公司提供的分析软件分析扩散张量图。包括:各向同性表面扩散系数(ADCiso)图和各向异性图,测量不同b值时图像的信躁比(SNR)及灰白质对比度。结果随着b值的升高,各相同性图及ADCiso图均显示脑组织灰白质对比度增高,b=2000s/mm2组(或b=3000s/mm2组)与b=1000s/mm2组有显著差异(P<0.001),b=2000s/mm2组与b=3000s/mm2组无显著差异(P>0.05)。结论①b=1000s/mm2时,DTI图像质量最好,但脑组织灰白质对比度不高。②b=2000s/mm2时,DTI图像质量较好,对比度较佳,能提供更多的扩散信息,更好地反应脑组织内水分子的扩散特性。③b=3000s/mm2时,DTI图像质量较差,对比度最好,但与b=2000s/mm2组差异不显著(P>0.05),而且增加扫描时间。笔者认为扩散梯度因子b=2000s/mm2时,图像综合质量最优,建议常规应用。更多还原

【Abstract】 Objective To evaluate the change of diffusion tensor ima gi ng (DTI) of normal human brain at different b values. Methods DTI were performe d on 28 healthy adults at b=1000 s/mm2, b=2000 s/mm2 and b=3000 s/mm2 respectively. Diffusion tensors maps, including ADCiso and anis otropic maps, were reconstructed by analysis software provided by Philips Corpor ation. Signal noise ratio (SNR) and contrast between grey matter (GW) and white matter (WM) were measured. Results Significantly increased contrast was revealed on isotropic map and ADCiso map. Significant difference was found between b=200 0 s/mm2 group(or b=3000 s/mm2) and b=1000 s/mm2 group, P< 0.001; while there was no significant difference between b=2000 s/mm2 group and b=3000 s/mm2 group (P >0.05). Conclusion ① The image quality of DTI is the best at b=1000 s/mm2, whi le the contrast between GW and WM is poor. ② Satisfying image quality and cont rast between GW and WM are obtained on DTI at b=2000 s/mm2, in which more diffus ion information is provided. And in this condition, the characteristics of water diffusion in brain tissue can be well displayed.③ There are nice contrast and worse SNR on DTI at b=3000 s/mm2, which has no significant difference with the D TI at b=2000 s/mm2 (P >0.05), and also extends the scan duration. In conclusion, DTI at b=2000s/mm2 may be a routine application due to better SNR and contrast.更多还原