docs: update caption of BOLD ROIs reportlet and boilerplate

Author: oesteban

fmriprep/data/reports-spec.yml

@@ -85,11 +85,14 @@ sections:
     subtitle: Alignment of functional and anatomical MRI data (surface driven)
   - bids: {datatype: figures, desc: rois, suffix: bold}
     caption: Brain mask calculated on the BOLD signal (red contour), along with the
-      masks used for a/tCompCor.<br />The aCompCor mask (magenta contour) is a conservative
-      CSF and white-matter mask for extracting physiological and movement confounds.
-      <br />The fCompCor mask (blue contour) contains the top 5% most variable voxels
-      within a heavily-eroded brain-mask.
-    subtitle: Brain mask and (temporal/anatomical) CompCor ROIs
+      regions of interest (ROIs) used in <em>a/tCompCor</em> for extracting
+      physiological and movement confounding components.<br />
+      The <em>anatomical CompCor</em> ROI (magenta contour) is a mask combining
+      CSF and WM (white-matter), where voxels containing a minimal partial volume
+      of GM have been removed.<br />
+      The <em>temporal CompCor</em> ROI (blue contour) contains the top 2% most
+      variable voxels within the brain mask.
+    subtitle: Brain mask and (anatomical/temporal) CompCor ROIs
   - bids:
       datatype: figures
       desc: '[at]compcor'
@@ -107,10 +110,11 @@ sections:
       in the BOLD data. Global signals calculated within the whole-brain (GS), within
       the white-matter (WM) and within cerebro-spinal fluid (CSF) show the mean BOLD
       signal in their corresponding masks. DVARS and FD show the standardized DVARS
-      and framewise-displacement measures for each time point.<br />A carpet plot
-      shows the time series for all voxels within the brain mask, or if ``--cifti-output``
-      was enabled, all grayordinates. Voxels are grouped into cortical (dark/light blue),
-      and subcortical (orange) gray matter, cerebellum (green) and white matter and CSF
+      and framewise-displacement measures for each time point.<br />
+      A carpet plot shows the time series for all voxels within the brain mask,
+      or if <code>--cifti-output</code> was enabled, all grayordinates.
+      Voxels are grouped into cortical (dark/light blue), and subcortical (orange)
+      gray matter, cerebellum (green) and white matter and CSF
       (red), indicated by the color map on the left-hand side.
     subtitle: BOLD Summary
   - bids: {datatype: figures, desc: 'confoundcorr', suffix: bold}

fmriprep/workflows/bold/confounds.py

@@ -141,8 +141,8 @@ def init_bold_confs_wf(
     from ...interfaces.confounds import aCompCorMasks
 
     gm_desc = (
-        'a probabilistic segmentation from the *aseg* segmentation' if freesurfer
-        else 'the corresponding partial volume map'
+        "dilating a GM mask extracted from the FreeSurfer's *aseg* segmentation" if freesurfer
+        else "thresholding the corresponding partial volume map at 0.05"
     )
 
     workflow = Workflow(name=name)
@@ -168,11 +168,10 @@ def init_bold_confs_wf(
 For aCompCor, three probabilistic masks (CSF, WM and combined CSF+WM)
 are generated in anatomical space.
 The implementation differs from that of Behzadi et al. in that instead
-of eroding the masks by 2 pixels on BOLD space, a liberal mask of the
-GM is obtained by thresholding {gm_desc} at 0.05.
-Then this mask is substracted from the WM and the combined CSF+WM masks
-to ensure components are not extracted from voxels containing a minimal
-fraction of GM.
+of eroding the masks by 2 pixels on BOLD space, the aCompCor masks are
+subtracted a mask of pixels that likely contain a volume fraction of GM.
+This mask is obtained by {gm_desc}, and it ensures components are not extracted
+from voxels containing a minimal fraction of GM.
 Finally, these masks are resampled into BOLD space and binarized by
 thresholding at 0.99 (as in the original implementation).
 Components are also calculated separately within the WM and CSF masks.