Hello all,

I think I just bumped into a weird bug while running 3dvolreg. I'm not sure if it is a 3dvolreg problem. Any suggestions/ideas are greatly appreciated.

I ran the following command for all of my participants and only got an errors on each of the 4 functional runs one subject's second imaging session. ("s06" is the subject and "_1" refers to that subject's first imaging session.) This code works for all other subjects.

3dvolreg -tshift 0 -rotparent anat_lpc_reg+orig -gridparent ../s06_1/run4_reg+orig -base run4_raw+orig.HEAD["$"] -1Dfile run1_motion.1D -prefix run1_reg run1_raw+orig.HEAD[4.."$"]

The output of this code is a 3D+t bucket where some of the time points are ok but some are almost completely zeros(0). I have attached images of index 20 to illustrate the problem (index 19, for example looks fine). As you can see from the timeline, the missing data are scattered thought the file.

It turns out that if we remove the -rotparent and -gridparent flags 3dvolreg works fine. Also the full processing stream for these files is "to3d -prefix run2_raw..." and "3drename run2_raw+orig run1_raw". (The call to 3drename is just to make scripting/file management easier.) If instead of using the file "run1_raw+orig" I use the original "run2_raw" file, 3dvolreg runs fine.

Any thoughts? Many thanks,

Antonio