Hello,
I have been running TBSS analysis on a group of 86 subjects. The processing steps all appear to complete correctly without any error messages, and allow me to run randomisation on them and generate the t-stat images which are also usable without any obvious problems. However upon inspecting the all_FA file which is generated during the tbss_3_postreg stage, it appears that the volumes in it from numbers 76-86 are incorrect; the data is displaced so that the brain appears to wrap around the edges of the image (appearing as two halves of a brain joined to the left and right borders of the image, I've tried to attach a picture of this to this post). More problematically, the FA data of these last eleven subjects is also exactly the same throughout the image. I have checked the files generated in the FA folder from the tbss_2 step and these all seem fine, so it looks as though the problem comes in merging these into the all_FA file.
To try and diagnose the problem I have ran an analysis on 81 subjects instead of 86, which carries the same issue from volumes 76-81. Another analysis where the eleven end subjects which have the error were placed at the beginning of the dataset instead still produced the same problem with volumes 76-86. I have also re-run the processing on another computer to find exactly the same error. Both my computer and this other one run FSL 4.1.7 on Linux and have 4GB RAM. Other TBSS analyses I have done with fewer subjects (usually around 50) have all been fine.
Any help that could be provided would be much apprecaited!
Regards,
Iain Croall.
|