[Freesurfer] pet surfer

Hi Dr Greve, I followed the steps in WIKI to do SUV-surface based analyses + PVC. I have the following questions and I highly appreciate your input:

1. Why the dimension of the images (mgx.gm, mgx.ctx.gm and mgx.ctx.subgm) is not like the original SUV image that has been fed to the pipeline. i.e. I start with image-dimensions 128X128X128 : 2X2X2 and end up with 79X113X102 : 2X2X2

Also FOV is different as well between the original SUV image /256/ and the output mgx images /158/. How this happen? I am I doing something wrong?

2. Some voxels in the mgx images has negative signal intensity. is this normal?

Thank you for any clarification. John