Hi all,

I’ve been using SPM8 for about 8 months now and thought I understood most of the basic functions pretty well.

Now I’m having a real problem with down sampling and interpolation choice.

I have T2 which needs to be resliced down to 5x5x7 mm in 64x54x17 voxels ( Arterial Spin Label Image).

I want the interpolation to be tri-linear,  which I thought was a ‘1’ in the options flag as shown in my code snippet below.

The output looks more like nearest-neighbor. Increasing the contrast to show any gradiant along the edge reveals that there is some kind of interpolation

applied since I see a few grey voxels along the edge. I suspect from the documentation that this is bilinear interpolation.

I don’t see a way to do tri-linear in the documentation or the MATLAB >>help spm_reslice

The program  flirt produces a much nicer resmapled image but I would rather keep my whole process in SPM8, because I start having issues with

keeping track of the affine transform information between different softwares.

Any advice is appreciated,

dpc

*****Begin code*****

T2 = spm_vol(‘T2.nii’);

ASL = spm_vol(‘ASL.nii’);

flags = struct('mask', 0, 'mean', 0, 'interp', 1 , 'which', 1,'prefix', 'rT2_');

files = {T2.fname, ASL.fname};

files = char(files);

spm_reslice(files,flags);