Open tsalo opened 3 years ago
Thank you for reaching out @tsalo!
think this is a reasonable rule under most circumstances, but it could be a problem for qMRI, so I figured I should check.
Matching volumetric dimensions would indeed be a good sanity check for file collections. I am trying to think of cases where spatial dimensions would differ within a file collection, but it is highly unlikely.
Not sure I follow. Do you mean all files in the file collection should be either 3D OR 4D? Or do you mean the size of the first 3 dimensions? Or actually only the 4th dimension?
@Gilles86 all of the above. If one file in a file collection is 3D (or 4D), they should all be. Additionally, all dimensions should match across files. In my specific case, only the fourth dimension was different, but I think it should hold for all of them.
I can't up with an example but it "feels" like a dangerous restriction to me. Who knows someone wants to do different readout schemes for different parts of the parameter sweeps or something...
Who knows someone wants to do different readout schemes for different parts of the parameter sweeps or something...
@Gilles86 that's why my understanding was to apply this rule to x,y,z.
@tsalo can we make this "recommended" and raise warnings if dimensions mismatch?
I can't up with an example but it "feels" like a dangerous restriction to me.
That's fair. It does sound like a less restrictive rule makes more sense for anatomical MRI. At least for fMRI, though, I can't imagine a case where this rule wouldn't apply, since in that case all file collections should come from the same scan.
@Gilles86 that's why my understanding was to apply this rule to x,y,z.
@agahkarakuzu I think I misunderstood. When employing different readout schemes within the collection, what would the effect on dimensions be?
@tsalo can we make this "recommended" and raise warnings if dimensions mismatch?
I think that's the best option. I can follow up with the validator, but I'll also need to open a PR to the specification to add a note about the new recommendation.
I've opened https://github.com/bids-standard/bids-validator/issues/1853 about this.
@tsalo I think warning is the best course of action here. Almost without exception, woxel-wise spatial correspondence is expected across individual images of a file collection. Then again, the keyword is "almost", there is always one or two things that make an exception.
For a majority of the cases, warning should act as a good sanity check.
I noticed recently that, due to what seems to be a random error, multi-echo and complex-valued fMRI runs in one of my datasets ended up with different lengths in different files. The validator didn't catch this, because I don't think there's a strict rule that files within a file collection have to have the same dimensions. I think this is a reasonable rule under most circumstances, but it could be a problem for qMRI, so I figured I should check.
Pinging @agahkarakuzu and @Gilles86.