[Mristudio-users] Fibertracking dorsal cingulum bundle

[mdfarid a r]

Dear DTIStudio users,

I am interested in investigating the cingulum bundle but am having trouble
fibertracking the cingulum bundle.

Based on the ColorMap0 and Eigenvector0 values in the region of the dorsal
cingulum bundle, I would expect fibertracking to occur in an
anterior-posterior manner but it is not the case.

1-ColorMap0.jpeg shows the ColorMap0. At the cingulum bundle region, the 2nd
value is the greatest among the 3. (eg: 19,126,27 or 6,136,40)

2-Evector0.jpeg shows the Eigenvector0. At the cingulum bundle region, the
2nd value is the greatest among the 3. (eg: -0.21,0.95,-0.20)

3-fibertrack.jpeg is obtained by fibertracking using the binary image of the
left cingulum mask from WMPMII
The threshold criteria is restrictive so that not too many fibers obstruct
the visualisation of the cingulum (threshold criteria is 0.3 for minimum FA
and angle of 50degrees). The resulting fibertrack is still unexpected
because it does not traverse in anterior-posterior manner but in the
dorsal-ventral manner.

Fibertracking at 0.15 minimum FA and angle of 70degrees. results in
4-fibertrack.jpeg. I further select the cingulum bundles by using the ROI
AND operation at different coronal slices.

At coronal slice 101, I am still able to obtain reasonable fibertrack
results. 5-fibertrack.jpeg, the fibertracks lie in the cingulum region that
is expected and extends over around14-18 slices from 101 to 114.

However, as I try to delineate the cingulum bundle at more anterior coronal
slices the cingulum is more horizontal, the fibertracking result
delineates in dorsal-ventral manner. In the 6-fibertrack.jpeg, the
fibertracks obtained extend over only 7 slices.

I do not understand how this is so because the ColorMap0 and the
Eigenvector0 seem to indicate that the principle diffusion direction is
indeed in the anterior-posterior direction.

-----------
Some other information
The image I used is a group registered to the JHU-MNI atlas. The images are
averaged across many subjects to increase signal to noise ratio. However,
when i repeat fibertracking on single subjects, the fibertracking results
are still more dorsal-ventral than anterior-posterior.
------------

Pls offer any suggestions. I really need the help. I can offer more
additional information on my problem if required.

Thank you in advance. I would really appreciate it.
Regards,
Farid
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