扩散磁共振成像中取向分布函数的球面插补方法

Spherical Interpolation of Orientation Distribution Function in Diffusion MRI

目的寻求一种基于少量采样数据即能实现白质纤维束路径跟踪的新方法,提出取向分布函数(orientation diffusion function,ODF)场球面插补算法,以解决q空间球面成像(Q-ball imaging,QBI)数据采样负担过重、耗时过长等临床应用瓶颈。方法首先基于采样数据重建ODF场,然后根据插补点与所有采样点之间夹角确定插补方向矩阵和宽度插补参数,之后基于自然指数函数来计算转换矩阵,最后对采样信号进行转换得到插补ODF场。结果采用流线跟踪法进行了白质纤维束路径跟踪,获得了较为合理的结果;并分析了角度宽度参数对插补结果的影响,确认了最适合的角度宽度参数选取准则。结论该球面插补方法基于少量采样数据即可实现ODF场的有效插补,可进行有效的白质纤维束路径跟踪。

Objective To find a new method that could track fiber paths based on fewer sampling datasets,the spherical interpolation algorithm of orientation diffusion function（ ODF） field was proposed to solve the timeconsuming and heavy-sampling problem of QBI in clinical application. Methods First,the ODF from raw sampling datasets was reconstructed. Then,the orientation matrix and the width parameter were calculated according to the angles between interpolating point and sampling points. Finally,the transform matrix was calculated based on natural exponential function. Results In order to verify our algorithm,the method of streamline was used to track the fiber paths,and reasonable results were obtained. In addition,the impact of angle width parameter on interpolation was also analyzed,and the selection criterion was confirmed. Conclusion The new method can achieve effective ODF interpolation for path tracking based on fewer sampling datasets.