Exact time of xcp_d

Dear Expert,

I’m using xcp_d 0.7.0rc1. I would like to use --exact-time to extract the FC from the same time length of the processed bold series. However, when checking the *_motion.tsv with the second column indicating the randomly chosen censored volumes, different subjects do not have the same number of censored volumes listed (calculating by the sum of this column), although the column name was created according to the same corresponding exact-time parameter. For example, I would like to extract 75 volumes, and the column name was created by exact_75, however, the sum of this column is 69 (I was expecting 75 instead), is that supposed to be so? Did I misunderstand something?

Thank you so much!

Can you send me the file so I can see what you’re referring to?

Actually, no need to do that. The 0 volumes are the ones that indicate that a volume is retained. You need to take the union of the 0 volumes in the “framewise_displacement” column and the 0 volumes in the “exact_75” column to get the final list of retained volumes in the exact-time relmats.

So it’s the combination of both columns having 0, got it! Thank you so much for your prompt reply!

1 Like

I have a further question concerning the related outputs of the FC while using this exact time. Our data have both directions of AP and PA, and for each phase, there are 2 sets of stat-personcorrelation outputs. The ones with _relmat correspond to scrubbed volumes, and -75volumes_remal correspond to volumes with exact time. After combined runs (using --combineruns), the final output is only _relmat, is that calculated based on the exact time if the “exact_75” column is available in that combined run *_outliers.tsv file? For some cases, this column is none, which means we don’t have enough exact time volumes requested after censoring, but there is still output of that combined run with stat-personcorrelation_relmat, so is this based on all volumes available? Thank you!

The output of combineruns is the correlation matrix from the full time series (not including high-motion outlier volumes, if you used --fd-thresh).

okay, so the exact time would not have the any effect on the combineruns rather than the separated directions. Thank you so much! However, it would be appreciated if the exact time can do the same thing to combineruns so we can utilize both phases and have exact same volumes (after removing the high-motion volumes) across all the subjects for further analysis. If I take this combineruns input as a raw to run the xcp_d again with -f 0, -p none and exact time, can I get the FC based on the exact time of the combineruns?