[Dtistudio-users] problem dealing with 41-directions DTI data

[Chung-Yi Yang]

Hi, all,

I am trying to use DTIstudio to deal with DTI data in 41 directions of
several cases, which were acquired on a GE Sigma scanner.
DTIStudio could read and display the dicoms correctly (DTI-mapping),
but it failed on Dtimap calculation (Tensor, color map etc.).
The problem is that only Eigen Value (EV) 0 is calculated, while the
EV1 and EV2 are zero for all pixels.
When I reload the DTI data, the gradient table I previously entered was changed.
It changed from

0: 0, 0, 0
1: -0.0126 , -0.7148 , -0.6992
2: -0.1053 , -0.9710 , -0.2145
3: 0.4315 , -0.8518 , -0.2971
...
...
41: 0.0317 , -0.2349 , -0.9715

to

 0: 0.000, 0.000, 0.000
 1: -0.013, 0.000, 0.000
 2: -0.105, 0.000, 0.000
 3: 0.431, 0.000, 0.000
...
...
 41: 0.032, 0.000, 0.000

This might explain why the program calculated only the EV0, since the
gradient table was altered. Is this a bug?

This never happened when I dealt with the 6-direction DTI data using
DTIStudio. The 6-direction gradient table remained the same when
I tried to load another data set.

Could anybody help me about this issue?

Thanks in advance,
Yang

-- 
Chung-Yi Yang M.D.
Department of Medical Imaging
National Taiwan University Hospital
Cell: 886-968662063