“runs” in Structural MRI - Purpose and Implications for Quality Control


I am working on a graduate research project using the ABIDE I and II autism datasets.

MRIQC has been run on these data - and I now must remove participants marked as outliers on 3 specific quality metrics. However, I have run into an issue - there appear to be multiple “runs” per participant.

If, on one run, the participant fails QC stipulations, but not on another run, does this mean that the participant should be excluded from analyses? Or is the purpose of having multiple “runs” in structural MRI in order to have sufficient data that, if one run is “bad”, another run can be used?

I have tried reading the MRIQC documentation; Googling; downloading and reading textbooks - for some reason, I find numerous resources on fMRI, but nothing for structural.

I would really appreciate any help anyone can offer - I am a bit desperate at this stage as my supervisors are on holiday.

Thank you for reading.