Hello-
Does anyone know how I can change positive pixdim values into negative
pixdim values for analyze files (or if this is possible)? The command
avwchpixdim lets me change negative to positive values but not positive to
negative. Alternatively, does anyone know how to run the avwswapdim command
in such a way that the pixdim value is NOT changed (i.e., by adding a flag
or some type)?
Here is some background on how I analyze my data and why I want a negative
pixdim value:
I use SPM2 to analyze my data. Before I do slice timing, I flip my data
along the x and y axis using the fsl 3.3 command avwswapdim. When I do this,
fsl changes my data from radiological to neurological format (the desired
effect) and also changes the pixdim variable for the X axis to a positive
number (an undesired effect). However, fsl 3.2 only changed the format but
did not change the pixdim variable. Because of this change from fsl 3.2 to
3.3 in the pixdim value, SPM2 displays my images and results in radiological
format (even though they are stored in neurological format) and an in-house
program that fixes bad slices of data does not work properly.
It is important to note that I do not actually want to change the
orientation of my data- I only want to change the value pixdim from a
positive to a negative value. I have explored the programs avwhd and
avwedithd, but these don't appear to have the pixdim value stored. I have
also tried to change the pixdim value in mricro and SPM2/matlab but have not
been able to find a way to do so.
Any help would be greatly appreciated!
Thanks,
Beth
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