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Manpage of threetenfit
threetenfit
Section: User Commands (1)
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NAME
threetenfit - Fits three diffusion tensors to diffusion MRI measurements.
SYNOPSIS
threetenfit
<data file> <scheme file> [-cylsym]
DESCRIPTION
Reads diffusion MRI data, acquired using the acquisition scheme
detailed in the scheme file, from the data file. The data file stores
the diffusion MRI data in voxel order with the measurements stored as
big-endian four-byte floats and ordered as in the scheme file. See
modelfit(1) for the format of the data file and scheme file. The
program fits three diffusion tensors to each voxel and outputs the
results, in voxel order and as big-endian eight-byte doubles, to the
standard output. The program outputs twenty-two values in each voxel:
[exitcode, ln(S(0)), m, a_1, D_1xx, D_1xy, D_1xz, D_1yy, D_1yz, D_1zz,
a_2, D_2xx, D_2xy, D_2xz, D_2yy, D_2yz, D_2zz, a_3, D_3xx, D_3xy,
D_3xz, D_3yy, D_3yz, D_3zz]. An exit code of zero indicates no
problems. For a list of other exit codes, see modelfit(1). The entry
S(0) is an estimate of the signal at q=0; m is the number of fitted
components, which is always 3 here; a_1 is the mixing parameter of
D_1, a_2 that for D_2 and a_3 that for D_3.
By default, the program constrains the three diffusion tensors only to
be positive definite. The program can also constrain the diffusion
tensors to have cylindrical symmetry (two equal eigenvalues). This
program is a simple interface to the program modelfit. The modelfit
program provides more options for fitting pairs of diffusion tensors.
If the first command line argument is - the program reads data from
the standard input.
EXAMPLES
Fit three positive-definite diffusion-tensors to the data in
SubjectA.Bfloat:
threetenfit SubjectA.Bfloat A.scheme > ThreeTensorA.Bdouble
Equivalently:
cat SubjectA.Bfloat | twotenfit - A.scheme > ThreeTensorA.Bfloat
Fit three cylindrically symmetric positive-definite diffusion tensors:
threetenfit SubjectA.Bfloat A.scheme -cylsym > ThreeTensorA.Bdouble
OPTIONS
- -cylsym
-
Constrain the diffusion tensors to have cylindrical symmetry.
AUTHORS
Daniel Alexander <camino@cs.ucl.ac.uk>
SEE ALSO
modelfit(1), dtfit(1), twotenfit(1), fa(1), trd(1), shfit(1),
shanis(1)
BUGS
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- EXAMPLES
-
- OPTIONS
-
- AUTHORS
-
- SEE ALSO
-
- BUGS
-
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