Dear asl experts,
What is the difference between the flags --diff and --surrdiff in the command asl_file
In asl_file's man, I see that --surrdiff was defined as: Do surround subtraction on the pairs. Please what is that means?
in my pcasl data, I have 90 volume (i.e. after converting he DICOMs to nii and visualizing the nii file using fslview). When I use the command :
asl_file --data={raw_data} --ntis=1 --iaf=tc --diff --out=diffdata --mean={output_name}
This output the file "diffdata" which contain 45 volumes. When i use the flag --surrdiff in the command asl_file. the output "diffdata" file contain 90 volumes. I am a little bit confused about these differences so I appreciate any clarification
Thanks!
John
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