Thanks so much for your response.
As Helen had also an EPI set with just one PE diresction I thought maybe she had found a way to resolve the problem of topup for just one PE direction. So how had she done that? What does she mean by blipup/blipdown images? I thought they should have been the first b=0 volumes of different EPI sets with different PE directions.
Among the data which have been delivered to me I have an EPI set with 35 gradient directions which I don't know how to determine the PE direction. Besides I have also two phase images and two magnitude images acquired with two different echo times.
Would you please help me to find how I can use these informations to correct my EPI for distortion and motion? Your help is highly appreciated. Everyone here is on holiday and I am left alone.