[Mristudio-users] WMPM

[susumu mori]

There are several types of WMPM. Actually our newer version of parcellation
maps include gray matter structures too.
So, we are now calling it Brain Parcellation Maps (BPM).

There are two type of parcellation maps; population-averaged and
single-subject.

ICBM-DTI-81 atlas is a population-averaged atlas, which has WMPM. Because
it is a population map, it is not a real brain. After averaging 81
subjects, many structures with high anatomical variability smeared out and
not definable anymore. For example, the fine white matter branches into the
cortex disappear. Therefore, we can define only the core of the white
matter. The WMPM contains structural definitions of only these core WM
regions.

In the averaged FA/color maps, you can clearly see core WM structures like
the internal capsule. We manually defined these structures. As you approach
to the cortex, we find pixels which are 100% WM in all 81 subject as well
as pixels which are only 50% WM (WM in 40 subjects and other 40 subjects
are the cortex). We can threshold the population averaged map at 90, 80,
70, and 60%. As the % goes up, the defined WM shrinks. If you superimpose
one of the WM structures with 90% threshold on your subjects (of course,
after normalization), it is highly likely that this ROI defines almost pure
WM with a small contamination of the cortex.

Does it make sense?

On Wed, Mar 6, 2013 at 10:59 AM, Shaimaa Abdelsattar
<shaimaa96 at hotmail.com>wrote:

> Hi,
> Could you please tell me the difference between the different types of
> WMPMs. I found what is called WMPM 80 % or etc.....
>
> Thanks
>
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