Dear Ariadna,
>
> I am trying to find my readout time and I found the following problem:
>
> 1. According to my MRI technician, my readout time equals (48-1)*0.744= 34.968 so 0.035 in seconds (since there are 48 echoes and 0.744ms echo spacing in our acquisition).
>
> Nevertheless, when I check the generated .json file, it says "TotalReadoutTime": 0.20094.
> Which readout-time should I use then for topup and why are they different?
I am not sure why they would be different. I think that is probably a question that is better suited for the nitrc/dcm2nii forum (assuming you used that for your conversion).
Having said that I don’t think a readout time of 0.2 seconds sounds at all realistic. 0.035 is much more in line with what I would expect. I am guessing you either have a 96x96 matrix with IPAT 2 or a 128x128 matrix with IPAT 3.
Also, for almost all applications of topup and eddy it doesn’t really matter what you set as the readout time. It is only in special cases such as when using dual-echo time fieldmaps with eddy, or when combining data with different readout times that it becomes critical.
>
> 2. Also, this "TotalReadoutTime" seems to be slightly different between participants, is this normal?
That sounds strange to me.
Jesper
>
> Thank you in advance,
>
> Ariadna
>
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