Hi Colin,
I'm not talking about tracking through grey matter. There are actual issues hitting the white matter surface (which is what you would want for tractography) uniformly between gyral crowns, banks, and sulcal fundi. This has to do with how the diffusion data behaves near the cortex and how cortical folding patterns influence the overall white matter architecture. Higher resolution may help with this, and better modeling. Peace, Matt. _____ From: caret-users-boun...@brainvis.wustl.edu [mailto:caret-users-boun...@brainvis.wustl.edu] On Behalf Of Colin Reveley Sent: Wednesday, January 11, 2012 12:20 PM To: caret-users@brainvis.wustl.edu Subject: Re: [caret-users] caret-users Digest, Vol 100, Issue 7 Thanks I'll look at that. Time consuming is something I do. I hope to make something of it with available tools. There are issues as you say. Conceptual issues. I would say it helps to have high bvals, high snr, high ang res and therefore a plausible diffusion signal, at least for 1st dist, in gm. which we do. that way you can seed and target one voxel up into the GM from a WM surface (or one down, or mix it up, and so on, but gm termini and seeds are an option) DW in GM is an area of research of particular interest to the guy who scanned the brain. But he's got the knowledge and the fancy equipment. not that a 10T MRI scanner or whatever it is for the connectome isn't fancy. is it even legal for persons? ;-> I think it isn't in the uk actually. not that there is one. there isn't. ---------- Forwarded message ---------- From: Matt Glasser <m...@ma-tea.com> To: "'Caret, SureFit, and SuMS software users'" <caret-users@brainvis.wustl.edu> Cc: Date: Tue, 10 Jan 2012 19:12:08 -0600 Subject: Re: [caret-users] FA->surefit Hi Colin, I have used the mean of f (mean_f1samples + mean_f2samples + mean_f3samples) to make surfaces from diffusion data. I threshold the image and then do manual editing to clean it up. It is timeconsuming, but possible to get high quality surfaces from this. I would note that surface-based tractography has some significant technical issues that need to be addressed before it will do what we want it to. This is something we are working on together with Oxford. Peace, Matt. _____ From: caret-users-boun...@brainvis.wustl.edu [mailto:caret-users-boun...@brainvis.wustl.edu] On Behalf Of Colin Reveley Sent: Tuesday, January 10, 2012 5:05 PM To: caret-users@brainvis.wustl.edu Subject: [caret-users] FA->surefit Before I hit my head against it pointlessly, but because there could be value in it, how much luck am I likely to have have in making a surface from a fractional asisotropy volume, or similar (something non-tensor that's a bit more complicated but still FA like to the eye, or else eg mean diffusivity) the point is to make masks from the caret surface that make sense in diffusion space (don't cross WM/GM boundaries as the diffusion measure sees them, rather than as a T1-like sequence sees them. this impacts on the probability that a streamline will hit a mask in gray or white, where gray always has low likelihood but white has high likelihood that the stream may be on its way somewhere else. ) It strikes me as worth something (registered to the rest...) in the context of everything else I'm looking at. It also strikes me as not worth it if it is just simply going to be yet another lengthy project to get it to work. Have surfaces been made from any diffusion maps using surfeit? mean diffusivity seems non-silly. I've got about ten million other maps. name it I have it. thanks as always best, Colin _______________________________________________ caret-users mailing list caret-users@brainvis.wustl.edu http://brainvis.wustl.edu/mailman/listinfo/caret-users
_______________________________________________ caret-users mailing list caret-users@brainvis.wustl.edu http://brainvis.wustl.edu/mailman/listinfo/caret-users
