vectors look a bit strange: is this expected?

[Elizabeth Olson]

Dear Frank,

I'm new to DTI Studio (though not to diffusion analysis) and am really enjoying it so far; thanks for all of your work on it.

I have been playing around with it a bit using just the DTI option and am a bit perplexed because the vectors that display in the bottom left panel when I open up the fib file look different than what I would expect. I'm attaching here screenshots of vectors from the same participant, one with the diffusion run in FSL (and V1 displayed), and one with the panel at bottom left in the fib file. As you can see, the vecs look much more 'disorganized' for lack of a better word in DSI Studio, especially in the blue direction.

I'm having trouble even figuring out whether this is really the V1 file that's displaying at bottom left when I open the fib, or if it's something else. If it is V1, why would it look so different than the FSL implementation?

Thanks for any help you might be able to offer.

Sincerely,

Liz 

McLean/HMS

[Frank Yeh]

They are both V1, and both figures look very similar to me (ignoring
the background intensity).
Frank

> --
> You received this message because you are subscribed to the Google Groups "DSI Studio" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to dsi-studio+...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/dsi-studio/965e6ee8-a531-4c2e-9732-123ef8b0d839n%40googlegroups.com.

[Elizabeth Olson]

Thanks so much for this speedy and reassuring feedback!

The thing that had me initially concerned was that I'm used to seeing the little lines for the vector orientation in each voxel pointing in the same direction along the tract, as in the circled red part of the pics attached below. The fact that the lines weren't oriented that way in DSI Studio had me a bit worried, but it sounds like that's fine and not something to fuss over here?

Thanks again,

Liz

[Frank Yeh]

It seems that there are some through-plane directions, and thus the
sticks appeared to be shorter.
You can increase the length of the stick line using the right upper
option window under [Region Window] to get a clearer result.
Frank

> To view this discussion on the web visit https://groups.google.com/d/msgid/dsi-studio/3cad065d-7baf-4d07-b689-f64bf4230fa5n%40googlegroups.com.

[Elizabeth Olson]

Ah terrific!! Those controls in the upper right window under 'Region Window' were super helpful; zooming, decreasing the fiber width and increasing the fiber length helped to show that everything looks as it should. Screenshot attached for posterity. 

Thanks again,

Liz

[Frank Yeh]

Glad to know it works for you.
Frank

> To view this discussion on the web visit https://groups.google.com/d/msgid/dsi-studio/8bc98330-5d8a-4309-a706-3b9d7fcdebean%40googlegroups.com.