Dear Sun,
sometimes you have the option to resample the data at the scanner, for example measuring with a 128 x 128 matrix, but the data is saved as a 256 x 256 matrix. But that's not your true resolution then.
The standard matrix size for fMRI is probably 64 x 64 with a voxel resolution of ~ 3 mm. A 256 x 256 matrix would mean your resolution was < 1 mm, this is common for structural T1 volumes. Maybe you intermixed these two? Or you did acquire some high-res fMRI data, then maybe some information are missing (parallel imaging allows a higher matrix size for example).
Best,
Helmut
|