敏感性编码技术和弥散敏感系数（b值）在兔肝VX2瘤扩散加权成像中的应用

目的探索敏感性编码（SENSE）技术和弥散敏感系数（b值）在兔肝VX2瘤快速MRI扩散加权成像实验中的应用。方法新西兰大白兔24只，于VX2瘤种植后2～3周行快速扩散加权成像（DWI）扫描。成像参数的缩减因子（reduction factor）取值为1，2，观察使用SENSE后扫描时间的缩短情况以及图像的信噪比变化情况。b值取100～600s／mm^2共6个。测量不同b值的兔肝VX2瘤与正常肝组织的信噪比以及相应的表面扩散系数（ADC），进行统计学分析。结果DWI中应用SENSE成像缩减因子为2时扫描时间缩短约13．3％，而图像的信噪比没差别（P≥0．05）。b值400s／mm^2时VX2瘤具有最高信噪比为115．5±71．6；ADC值为1．575±0．218×10^-3mm^2／s（P〈0．05）。结论 合理应用SENSE技术能缩短扫描时间而图像信噪比没有差别，弥散敏感系数（b值）为400s／mm^2是最优b值，兔肝VX2瘤与正常肝组织的信噪比最高，其ADC值最准确。

Application of SENSE technique and diffusion sensitivity coefficient(b-value)in MR diffusion weighted imaging of rabbit VX2 liver tumors

Objective To investigate the application of SENSE technique and diffusion sensitivity coeflicient（b - value） in TSE MR diffusion weighted imnging（DWI） of experimental rabbit VX2 liver tumors. Methods TSE MR DWI scans were performed in all the 24 New zealand rabbits at 2-3 week after VX2 liver tumor implantation. The reduction factor of imaging parameter was taken as 1 and 2, the shortening of scanning times and the changes of imaging signal- to- noise ratio（SNR）were observed by using SENSE technique. The b- value was used by total 6 values from 100 s/mm^2 to 600 s/mm^2. SNR and apparent diffusion coeflicient（ADC）between VX2 liver tumor with different b - values and normal liver tissue were measured for each rabbit and statistically analyzed. Results When use reduction factor 2, the scanning time was shortened by 13.3%, while the imaging SNR had no difference during DWI. When the b - value was 400 s/mm^2, the rabbit VX2 liver tumors had a highest SNR （ 115.5 ± 71.6） ; ADC value was 1. 575 ±0. 218 × 10^- 3mm^2/s （ P〈 0. 05）. Conclusion Reasonably use SENSE technique can shorten the scanning time but the imaging SNR has no difference. The b - value teken as 400 s/mm^2 is optimal, in which the SNR between VX2 liver tumor and normal liver tissue is highest and the ADC value is also most accurate.