fa - Computes the fractional anisotropy of tensors.
SYNOPSIS
fa
[-inputmodel <dt|twotensor|threetensor|multitensor>]
DESCRIPTION
Reads diffusion tensor (single, two-tensor or three-tensor) data from the standard input,
computes the fractional anisotropy (FA) of each tensor and outputs the results to the
standard output. For multiple-tensor data the program outputs the FA of each tensor, so
for three-tensor data, for example, the output contains three fractional anisotropy
values per voxel.
EXAMPLES
Compute the FA in each voxel of diffusion MRI data set SubjectA.Bfloat and store the
output in FA_A.Bdouble:
dtfit SubjectA.Bfloat test/A.scheme | fa > FA_A.Bdouble
Compute the FA for each component of the two-tensor fit to the same data set:
twotenfit SubjectA.Bfloat test/A.scheme | fa -inputmodel twotensor > FA_A.Bdouble
Compute the FA for 10000 independent trials of fitting the diffusion tensor to data
synthesized from test function 1 (see datasynth(1)) using imaging scheme A.scheme and
assuming signal to noise ratio of 16 at b=0:
Specifies the model that the input data contains parameters for. Possible model types
are: "dt" (diffusion-tensor data), "twotensor" (two-tensor data), "threetensor"
(three-tensor data), and "multitensor" (see multitenfit(1)). By default, the program
assumes that the input data contains a single diffusion tensor in each voxel.
-inputdatatype <data type of input>
Specifies the data type of the input file. The data type can be any of the following
strings: "char", "short", "int", "long", "float" or "double". See camino(1).
-outputdatatype <data type of output>
Specifies the data type of the output data. The data type can be any of the following
strings: "char", "short", "int", "long", "float" or "double". See camino(1).