弥散张量成像技术初步评价视放射

目的探索临床可接受的视放射成像扫描计划和相应图像后处理方法。方法对10例正常自愿者(男6例,女4例),年龄20～45岁,平均28岁,以1.5T磁共振扫描仪行DTI扫描,弥散梯度磁场(MPG)选择6、14、323个方向,扫描时间5分钟左右。利用DTI Studio软件,采用多感兴趣区(ROI)法进行图像后处理,重建视放射纤维束,比较三组图像信噪比(SNR)、视放射迈耶袢显示情况以及图像视放射纤维束平均长度与密度。结果三组图像比较,SNR组间差异无统计学意义;6MPG与32MPG组间在迈耶袢显示方面差异有统计学意义。研究三组资料间两两比较,平均纤维束长度与密度的差异均具有统计学意义。结论在1.5T场强、32MPG下、约5分钟扫描时间内,采用多ROI后处理方法,可以得到临床较为满意的视放射纤维束图像。

Preliminary assessment of fiber tractography of optic radiation based on diffusion tensor imaging

Objective To investigate optimal scan plan for optic radiation tractography and image post-processing method which is acceptable for clinics. Methods Diffusion tensor imaging (DTI) was obtained in 10 healthy volunteers (6 men,4 women,aged 20-45,with an average age of 28 years) using a 1.5T MR scanner with single-shot echo-planar imaging with SENSE technique. Motion-probing gradient (MPG) was applied in 6,14,and 32 independent directions to tract optic radiation fibers. Software DTI Studio was used for image post-processing with a multi-ROI measurement accompanied by "or","and" and "not" operation,to assess image effect by comparing its signal to noise ratio (SNR),the demonstration of Meyer's loop through analyzed the difference of average length of fibers and mean fibers/voxel among the three groups. Results There was no significant difference for SNR among the three groups. The demonstration of Meyer's loop was obviously better in the group of 32 MPG than that in group 6 MPG,and statistical difference existed in average fiber length and mean fibers/voxel among the three groups. Conclusion An acceptable fiber tract image can be obtained in moderate scan time (about 5 minutes) under 32 MPG with a method of multi-ROIs image post-processing in 1.5T MRI scaner.