Dear FSLers, I would like to know about the application of TOPUP and applytopup. I have acquired two short EPIs, each with 3 volumes (A_P and P_A) in anterior to posterior and posterior to anterior directions. I need to correct the distortions of my resting state EPI, which is acquired in P_A direction. After applying the commands below, I can anticipate that my_hifi_images with 3 volumes does not have susceptibility induced distortions. fslroi A_P b0_blip_up 0 1 fslroi P_A b0_blip_down 0 1 fslmerge -t both_b0 b0_blip_up b0_blip_down topup --imain=both_b0 --datain=my_acq_param.txt --config=b02b0.cnf --out=my_topup_results applytopup --imain=A_P,P_A --inindex=1,2 --datain=my_acq_param.txt --topup=my_topup_results --out=my_hifi_images Kindly suggest that how the susceptibility induced distortions of my resting state EPI can be corrected using applytopup? Thanks and Regards Himanshu Joshi