dwiMD-methods: Methods for Function 'dwiMD' in Package 'dti'

Description Usage Arguments Value Methods Author(s) References See Also Examples

Description

The method calculates, in each voxel, the mean diffusivityfrom the DWI data contained in an object of class "dtiData" or from the estimated diffusion tensor in an object of class "dtiThensor"

Usage

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  ## S4 method for signature 'dtiData'
dwiMD(object, eps=.05)
  ## S4 method for signature 'dtiTensor'
dwiMD(object)

Arguments

object

Object of class "dtiData" or class "dtiTensor"

eps

In case of an "dtiData" object the method searches for three approximately orthogonal gradient directions. The mean diffusivity is then calculated using the observed apparent diffusion coefficients for these gradients. The search is terminated if a measure for deviation from orthogonality is smaller than eps

Value

An array of mean diffusivity values.

Methods

obj = "ANY"

Returns a warning.

obj = "dtiData"

calculates mean diffusivity from 3 approximately orthogonal gradient directions

obj = "dtiTensor"

calculates mean diffusivity from estimated diffusion tensors

Author(s)

Karsten Tabelow [email protected]
J\"org Polzehl [email protected]

References

J. Polzehl and K. Tabelow, Beyond the diffusion tensor model: The package dti, Journal of Statistical Software, 44(12), 1-26 (2011).

J. Polzehl and K. Tabelow, Structural adaptive smoothing in diffusion tensor imaging: The R package dti, Journal of Statistical Software, 31(9) 1-24 (2009).

http://www.wias-berlin.de/projects/matheon_a3/

See Also

dtiData, readDWIdata, dtiIndices-methods, medinria, dtiData, dtiTensor dwiMixtensor

Examples

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  ## Not run: demo(dti_art)

Example output

Loading required package: awsMethods

Use the function setCores() to change the number of CPU cores.

Loading required package: adimpro
sh: 1: cannot create /dev/null: Permission denied
sh: 1: cannot create /dev/null: Permission denied
sh: 1: cannot create /dev/null: Permission denied
Reading RAW images requires to install dcraw, see 

    http://cybercom.net/~dcoffin/dcraw/ for LINUX and http://www.insflug.org/raw/ 
    for MAC OS and Windows 

Loading required package: rgl
Warning messages:
1: In fun(libname, pkgname) : could not determine path to Imagemagick 

    please set the correct path manually using 

    'Sys.setenv(ImageMagick='path2imagemagick')'
2: In rgl.init(initValue, onlyNULL) : RGL: unable to open X11 display
3: 'rgl_init' failed, running with rgl.useNULL = TRUE 
4: .onUnload failed in unloadNamespace() for 'rgl', details:
  call: fun(...)
  error: object 'rgl_quit' not found 

dti documentation built on May 29, 2017, 3:50 p.m.