Diffusion Tensor Imaging - Computing The Tensor

Having set up the gradients and b-matrices, set the input images, and setup for warp correction (if necessary), you are now in a position to compute the tensor images. You will need to decide on several settings in the Tensor Calculation panel:

A panel to setup for tensor fitting

You are now ready to compute the tensor: click the Button to calculate the diffusion tensor button. If you obtain satisfactory results, you can save the whole setup by clicking the Button to save the tool settings button. Then, the next time you use the Diffusion Analysis tool, the same settings will be retrieved. To revert to the default setting, click the Button to set the tool defaults.

Below are some typical output images for one slice.
Example tensor output images images.
M0 intensity image Diffusion tensor trace image Diffusion tensor fractional anisotropy image Diffusion tensor relative anisotropy image
M0 Trace Fractional anisotropy Relative anisotropy
Diffusion tensor axial diffusivity image Diffusion tensor radial diffusivity image Diffusion tensor primary eigen vector direction image
Axial diffusivity Radial diffusivity Direction
Also output is the full diffusion tensor. This is a 4-dimensional dataset, containing the six unique elements of the tensor in the order Dxx, Dxy, Dxz, Dyy, Dyz, Dzz, shown below:

Diffusion tensor elements image

Note: the Dxx elements for all slices are followed by the Dxy elements for all slices, etc.

Having computed the diffusion tensor (and its scalar rotational invariants), you can go on to used the outputted Diffusion Tensor (DT) image to perform tractography.

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