Analysis of interpolation effects in the reslicing of functional MR images

Purpose: Typically, the final step in volume registration is the reslicing of the volume of interest. The purpose of this work is to examine the effects of this reslicing on functional MRI (fMRI) data using different interpolation methods. Method: Functional whale-brain echo planar imaging (EPI) volumes were resliced using six different interpolation methods: trilinear, tricubic splines, and a 3D sine function using a rectangular and a Hanning window, both with half-window lengths of 3 and 4 voxels. Results: Interpolation by tricubic spline and 3D sine using a Hanning window had comparable errors, although tricubic spline interpolation was computationally the fastest. Interpolation by trilinear and 3D sine using a rectangular window had relatively large errors, although the speed of trilinear makes it desirable for some applications. Conclusion: Interpolations using all of the tested methods adversely affected the fMRT data, although these effects differed for each method.