ACT usage and fiber tracts comparison

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Hi, Rob,

Appreciate the response and thank you for helping clear the concept of connection density normalization.

  1. I further generated fiber tracts in the disease group and healthy group with SIFT and non-SIFT, respectively. SIFT or not SIFT, nigrostriatal fiber loss can be seen obviously when comparing the two group subjects. With such consistent results, is it reasonable to say the fiber tracking results could be acceptable even without the quantitative benefits that SIFT provides in this case? Cause I’m considering to produce more data with such a procedure and without SIFT may be faster.

  2. About -vector option in tensor2metric. Due to the background that the disease leads to neuron death in this brain region. We consider such a phenomenon may affect water molecule diffusion and then affect the fiber tracking results. In addition to the reconstructed fiber length, we suspect the phenomenon may also contribute to fiber direction changes, especially those fibers departing from this brain region. The steps:
    First, tensor2metric -vector vectimage.nii.gz has been applied for generating the principal vector images, rather than all three components.
    Second, tcksample was used to extract the direction information from the principal vectors, with vectimage.nii.gz as input images and the output scatter values. I guess it may help identify axial and radial diffusivities. Or, maybe I did something wrong here. Fixel images may better describe directions, I didn’t test it though.

A lot of thanks!
Chaoqing