Hey,
I am very new to working with AFNI and I hope you can help me. I have an input FSL cluster image which I want to apply as a mask onto a dataset to compute the average of all the voxels in specific clusters. Yet some of the clusters are huge so I would like to define a region of interest around the maximal activation of the cluster and average the activation only in this part of the cluster. I try to do it this way:
3dmaskave -mask /my_path_to_the_cluster/clusterIndex.nii.gz -quiet -xball -57 -30 36 10 /my_path_to dataset.nii.gz > /my_path_to_output.txt
The error I get is
5231 voxels survive the mask
++ 57 voxels in the boxes+balls
** FATAL ERROR: No voxels in the mask INTERSECT boxes+balls!
which I eventually am able to overcome if I increase the radius of the ROI. I just don't understand why wouldn't the defined sphere intersect with the cluster if it is literally defined inside of it. Does someone have an idea of whyit happens?
Thanks!
Lisa