Downsampled Parcellation Mask for Tck2connectome

After tractography, can a downsampled image be used in the same diffusion space and get a downsampled connectivity matrix? Thank yall in advance for your insights!

Kind Regards,


Hi Ric,

I think your description needs to be a little more verbose. I’m concerned that the word “downsampled” is being used in one sentence in two different ways:

  • For images, “downsampling” refers to resampling the image data on a voxel grid where the voxel size is larger.

  • For connectivity matrices, “downsampling” refers to … ?

    • Do you mean a connectivity matrix based on a parcellation image with fewer unique nodes? If so I’d absolutely avoid using the word “downsampling” here, even if the graph theory aficionados use it in that way, but there’s no reason tck2connectome can’t be run multiple times with a different parcellation image each time.

    • If you just mean “a connectome matrix that was produced from a parcellation image that was downsampled”, then the answer is yes. tck2connectome doesn’t even receive the diffusion image as input, so it’d be oblivious to the fact that the parcellation image you gave to it isn’t on the same voxel grid as the image used to produce the streamlines you gave to it. Indeed this is very common, since parcellations are often based on the corresponding T1-weighted image, and the atlas will be transformed and re-gridded to the T1-weighted image, or indeed generated natively on the T1-weighted image voxel grid in the case of FreeSurfer.