thanks Matt and Jesper for your answers. our resting state and fmri sequences are EPI-GRE. after visual inspection, as you suggested, results seems fine. For future recordings, assuming "...GRE images are not recommended for use in computing a topup field....." what would you suggest me to correct my epi-gre? thanks in advance regards, Alberto ######################################################################## To unsubscribe from the FSL list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=FSL&A=1 This message was issued to members of www.jiscmail.ac.uk/FSL, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/