Hi Flora, it is good to know that the values in the txt files thresholded at 80%, thanks for this information (because masking is, as you said, at 10%). I am going to send you the data to your email. The results of the .txt-files (/native_space/pvcorr/perfusion_calib_gm_mean.txt) looks fine: subject1: 68.153289 subject2: 56.726537 subject3: 69.697941 I always thresholded with 10% and I guess the PVC is not applicable for lower PV percent (<50%)... However, would you mind to look at the data? I would appreciate it. Thank you for your help, Regards, Rune ######################################################################## To unsubscribe from the FSL list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1