QSIPrep carpet plot

Hi all,

I am new to working with the QSIPrep pipeline and am relatively new to working with DTI. I am having some issues interpreting the carpet plot from the pipeline. I have read all the documentation that I can find but none of this is detailed enough to answer my questions.

Firstly, I am presuming that the x-axis is the volumes acquired across time and that the y-axis is the slices from the volumes. Is this correct?

I have also noticed that the information about the framewise displacement does not match the information provided in the ImageQC csv file. The means are roughly the same but not exact and sometimes the max framewise displacement doesn’t match at all.

Also, how is the value for this line that runs through the frame wise displacement plot calculated? Sometimes it appears to me that when the frame wise displacement plot crosses this line all the slices in this volume appear dark blue, as if the whole volume is removed?

Another issue, I believe that the number of bad slices given in the ImageOC csv file does not match what I am seeing in the carpet plot.

I know there is a few questions here but if someone could help me interpret this plot I would be very grateful as I think it could be useful in the QC process.

Thanks in advance.