[caret-users] Quetion about data acquisition

Matt Glasser matt at ma-tea.com
Thu Nov 29 10:30:54 CST 2012


You'd have to ask the NAMIC people about the bandwidth for their scans.  I
provided all the information I could find on that data.

I'm not sure what scans you are varying the parameters of there.

Did you use percentile scaling?

The bias fields are not really dependent on most parameters.  The contrast
of the images will be, you of course will want to maximize contrast for
grey matter myelin differences to get the best results.

The T1w/T2w ratio is what is mapped onto the surface.

Peace,

Matt.

On 11/29/12 2:55 AM, "Yuichiro Shimizu" <yuichirosmz at gmail.com> wrote:

>Hello,
>
>Thanks to your adequate instruction, by running fslreorient2std, I
>obtained images that are similar to Figure 3 (Glasser et al. 2011).
>Thank you very much!
>
>Now, there are three questions about myelin mapping.
>
>First, it is about scanning parameters.
>In the paper, there was no information about bandwidth for GE MRI.
>So I got some scans changing bandwidths without changing TE.
>Here are parameters that I tried.
>
>Condition1 bandwidth 83.33 ETL 105 TE 80.5
>Condition2 bandwidth 62.5  ETL 105 TE 80.5
>Condition3 bandwidth 31.25 ETL 70  TE 79.9
>
>Then I performed myelin mapping with each condtions.
>The relations of intensities in color maps were similar,
>but the mapped colors for each conditions were quite diffrent.
>(I uploaded those data for condition 1-3)
>So, what I want to know is how the parameters were determined and why.
>And, what is the range of parameters can be used for myelin mapping?
>
>
>Second, there are approximations in the paper, T1w=x*b and T2w=b*(1/x).
>What are the range of parameters that these approximations are valid?
>
>
>Finally, for mapping final surface, which data are used, x or squared x?
>And I want to compare subjects by examining absolute values of x,
>what points should I care about?
>
>Sincerely.
>
>Yuichiro Shimizu
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>caret-users at brainvis.wustl.edu
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