Euclidean distance between two volumetric ROIs

AFNI Message Board
1

Hi all,

I have preprocessed a set of resting state images using AFNI ver 21.2.04 (‘Nerva’). The anatomical images were sent through SSwarper and recon-all and my proc.py script was modeled after example 11. I am using a functional atlas that consists of 90 ROIs in MNI space. I was hoping to calculate some QC-FC metrics as described in Ciric et al (2017) to evaluate the distance-dependent effects of motion on functional connectivity before and after denoising. To do this, a distance matrix is created by calculating the euclidean distance between the centers of mass of all node pairs. Using the 3dCM command I was able to extract the center of mass of each ROI. For calculation of the euclidean distance, I see the SurfDist command, however, my data is volumetric rather than surface-based. Is there any other function in AFNI that can be used to calculate euclidean distance between each ROI pair center of mass in volumetric space?

Thanks!
Jenna

2

Hi Jenna,

It would not be too difficult to script such a thing, but for convenience, I added a -show_distmat option to 1d_tool.py.
The input would be a file of coordinates (or motion parameters or other vectors), one vector per row. The output would be an NROW x NROW matrix of pairwise distances.

This is not yet built, but should be available later today.

  • rick
3

Hi Rick,

Great! Thank you for adding the option!

Best,
Jenna

4

Hi Jenna,

This update should be available now. Just let me know if you have questions.

  • rick