sdeconv

Description

perform linear spherical deconvolution.

Note that this program makes use of implied symmetries in the diffusion profile. First, the fact the signal attenuation profile is real implies that it has conjugate symmetry, i.e. Y(l,-m) = Y(l,m)* (where * denotes the complex conjugate). Second, the diffusion profile should be antipodally symmetric (i.e. S(x) = S(-x)), implying that all odd l components should be zero. Therefore, this program only computes the even elements.

Note that the spherical harmonics equations used here differ slightly from those conventionally used, in that the (-1)^m factor has been omitted. This should be taken into account in all subsequent calculations.

Each volume in the output image corresponds to a different spherical harmonic component, according to the following convention:

[0] Y(0,0)

[1] Im {Y(2,2)}

[2] Im {Y(2,1)}

[3] Y(2,0)

[4] Re {Y(2,1)}

[5] Re {Y(2,2)}

[6] Im {Y(4,4)}

[7] Im {Y(4,3)}

etc...

syntax:     sdeconv [ options ] dwi response SH

Arguments

dwi the input diffusion-weighted image.
response the diffusion-weighted signal response function for a single fibre population.
SH the output spherical harmonics coefficients image.

Options

-grad encoding specify the diffusion-weighted gradient scheme used in the acquisition. The program will normally attempt to use the encoding stored in image header.
encoding the gradient encoding, supplied as a 4xN text file with each line is in the format [ X Y Z b ], where [ X Y Z ] describe the direction of the applied gradient, and b gives the b-value in units (1000 s/mm^2).
-lmax order set the maximum harmonic order for the output series. By default, the program will use the highest possible lmax given the number of diffusion-weighted images.
order the maximum harmonic order to use.
-mask image only perform computation within the specified binary brain mask image.
image the mask image to use.
-filter spec apply the linear frequency filtering parameters specified to the spherical deconvolution.
spec a text file containing the filtering coefficients for each even harmonic order.
-normalise normalise the DW signal to the b=0 image
-info display information messages.
-quiet do not display information messages or progress status.
-debug display debugging messages.
-help display this information page and exit.
-version display version information and exit.

Donald Tournier
MRtrix version 0.2.12
Last updated 2009-09-25