Dear FreeSurfer experts

I am a relative novice with FreeSurfer. I am reprocessing some older images with v6.0 that were previously processed with v5.3. In the newer batch, the GM-WM boundary is wider and the pial boundary is pushed out, but the newer version does a better job in the hippocampus. I am trying to figure out what parameters might differ between versions so I can get a cortical reconstruction as well as hippocampal segmentation. Both batches used plain vanilla recon-all -all.

The attached figure shows v5.3 on top and v6.0 below, with aseg.mgz over T1.mgz. I used an example that as well as thin cortex in the new version, shows a hippocampal error in the older version. (The slices are aligned at the hippocampus, but the pitch is slightly different so they don't line up more superiorly.)

>From the T1, it looks like the step that sets white matter to 110 is more aggressive in 6.0. I looked through recon-all.cmd and noticed both normalization steps include the -mprage flag in 6.0 not 5.3.Could this be the why the results differ? (The images are SPGR not MPRAGE.) Looking at help for mri_normalize it doesn't mention this flag or how to switch it off, so I'm stuck here. Of course, it might be something else, not the -mprage flag.

I'd much appreciate any guidance from the list.

Best wishes

Paul