Convert .vtk to .nii

Hello,

I have a .vtk file (in this case, it is brain atlas) that I wish to use with CONN (a MATLAB toolbox for analyzing fMRI data). CONN does not support .vtk files, but it does support .nii, .gz, .img, ...

I was wondering if there is a way to convert this .vtk file into one of these file types so that it may be opened with CONN.

Thanks all for the assistance!

- Conor