BIDS conventions for motion measures/parameters?

sgiavasis · November 9, 2021, 5:49pm

Hello,

I’ve searched and haven’t found anything- in the BIDS scope, is there any language, or any agreed-upon wording for derived motion measures or parameters? For example, 1D data of framewise displacement, per time point, from an fMRI time series.

Specifically, other than having it be a TSV file, would like to know if there is any convention for the final *_suffix.TSV for such derivative data.

Thank you!

Remi-Gau · November 10, 2021, 7:10am

I think this is touched upon in the BEP12:

github.com

bids-standard/bids-specification/blob/bep012/src/05-derivatives/05-functional-derivatives.md#general-time-series

# Functional derivatives

## Functional derivatives maps

A derivative map is a measure derived from a functional series, mapped onto spatial
locations as defined by voxels in a volume or vertices on a surface.

Template:

```Text
<pipeline_name>/
    sub-<label>/
        func/
            <source_entities>[_space-<space>][_res-<label>][_den-<label>][_desc-<label>]_<suffix>.{nii[.gz],gii,dscalar.nii}
            <source_entities>[_space-<space>][_res-<label>][_den-<label>][_desc-<label>]_<suffix>.json
```

for example:

```Text

This file has been truncated. show original

The suffix would be timeseries. I believe this is what the latest versions of fmriprep do.

_timeseries.tsv

@effigies should be able to confirm

effigies · November 10, 2021, 1:15pm

_timeseries.tsv is the generic container. BEP 012 also permits _timeseries.tsv to be broken into semantically meaningful groups that have constraints on permissible columns. Motion-related time series can be put in _motion.tsv.

sgiavasis · November 10, 2021, 4:57pm

The motion-related time series section is just what I was looking for.

Thank you both!

sgiavasis · November 10, 2021, 7:41pm

Oh, one more question before I mark solved- we want to include many motion-related, summary/calculated single values in one TSV, each one labeled (which would not be a time series, just a column or row of many unrelated values).

Would it be BIDS compliant to name this *_desc-summary_motion.tsv, or does *_motion.tsv imply that it is a time series?

effigies · November 15, 2021, 3:28pm

If I were going to put summary values for a given scan, I would either drop them into each scan’s JSON or use the BIDS scans.tsv concept. AFAIK nobody is currently using those as derivatives, but it should be perfectly valid.