Hi,
I have a couple of questions regarding the output data when I used the FEAT Gui to do
distortion correction of DTI data. The movie section comparing distorted and undistorted
example_func data (third last rows) showed a stationary row of images ( i.e there is no
flipping between one image to another). When I tried to fslview the example_func.nii.gz,
filtered_func_data.nii.gz or the example_func_orig_distorted.nii.gz, i could only view the
first two and not able to view the last image. Also in all cases, there would be error
messages as below for all three:
ERROR (nifti_image_read): failed to find header file for
'/Users/siewmingan/Desktop/DATASET/patient_1/tryfieldmap_y.feat/stats/pe1'
** ERROR:
nifti_image_open(/Users/siewmingan/Desktop/DATASET/patient_1/tryfieldmap_y.feat/stat
s/pe1): bad header info
Error: failed to open file
/Users/siewmingan/Desktop/DATASET/patient_1/tryfieldmap_y.feat/stats/pe1.
Why does the error message occurs and how I can resolve it?
Because the movie section did not display the contrast between the distorted and
undistorted images, and the 4th row displaying the original distorted images looks
similiar to the 5th row displaying the undistorted images , and I couldn't view the
example_func.nii with the example_func_orig_distorted.nii.gz, I then tried to compare the
example_func.nii.gz with my original 4D data file. I noticed the intensity in the
example_func.nii.gz file is around 2-3 times lower than the original 4D data. May I ask
why that would be so and would that be a problem? Also, if both the example_func.nii.gz
file and the filtered_func_data.nii.gz are both the undistorted 4D DTI data from running
FEAT, why do they have different intensity with the former in 100s and the latter in
10000s?
Apart from the difference in the intensity in the original 4D data and the
example_func.nii.gz, it was quite hard to detect differences due to the different intensity
of the brain on display ( I've tried both distortion correction with the "y" and "-y" option.)
Is there any way to resolve the previous error messages so I can directly compare the
distorted and undistorted images with the same intensity, and check if I have done the
distortion correction step correctly?
Many Thanks
Siewmin
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