Hello everyone,
I have many scans taken just under 10 years ago on a 1.5T Siemens
scanner. For some reason, the images from this time period have
consistent problems with gray matter / white matter contrast;
consistently, Freesurfer measures almost all cerebral brain tissue as
being white. I have experimented with mri_ca_normalize (turning -p down
to 0.25 or so helps), with mri_normalize (using -prune helped somewhat,)
but all of these trials are experimental and I haven't gotten a solid
script written that handles these special cases for me in an efficient
way.
My question: has anyone else dealt with this problem regularly, and come
up with a good way to either use recon-all to take care of it (I can't
find any useful flags, or workflow tutorials for dealing with this on
the wiki) or written a handy script to do recon-all with several of
these "less wm" options built in? I have seen people ask about issues
relating to mri_ca_normalize on the mailing list in the past, but the
conversations usually end with "send us some of your data and we'll take
a look at it."
Or, am I missing something here? Did someone already discuss this in
detail? Sorry if this seems obvious. Thanks in advance for any help...
Victor Laluz
UCSF Memory and Aging Center