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Coregister B-Values

Coregister B-Values

User Interface

General Information

Module Type & Category

Type: CLI

Category: Diffusion.GTRACT

Authors, Collaborators & Contact

Author: This tool was developed by Vincent Magnotta and Greg Harris.


Contact: name, email

Module Description

Program title Coregister B-Values
Program description This step should be performed after converting DWI scans from DICOM to NRRD format. This program will register all gradients in a NRRD diffusion weighted 4D vector image (moving image) to a specified index in a fixed image. It also supports co-registration with a T2 weighted image or field map in the same plane as the DWI data. The fixed image for the registration should be a b0 image. A mutual information metric cost function is used for the registration because of the differences in signal intensity as a result of the diffusion gradients. The full affine allows the registration procedure to correct for eddy current distortions that may exist in the data. If the eddyCurrentCorrection is enabled, relaxationFactor (0.25) and maximumStepSize (0.1) should be adjusted.
Program version 4.0.0
Program documentation-url -


Use Cases, Examples

This module is especially appropriate for these use cases:

  • Use Case 1:
  • Use Case 2:

Examples of the module in use:

  • Example 1:
  • Example 2:


  • Tutorial 1
    • Data Set 1

Quick Tour of Features and Use

A list panels in the interface, their features, what they mean, and how to use them.

  • Input Image Parameters
    • Moving Image Volume [--movingVolume] : Required: input moving image file name. In order to register gradients within a scan to its first gradient, set the movingVolume and fixedVolume as the same image.
    • Fixed Image Volume [--fixedVolume] : Required: input fixed image file name. It is recommended that this image should either contain or be a b0 image.
    • Fixed Image Index [--fixedVolumeIndex] : Index in the fixed image for registration. It is recommended that this image should be a b0 image. Default value: 0

  • Output Files
    • Output Image Volume [--outputVolume] : Required: name of output NRRD file containing moving images individually resampled and fit to the specified fixed image index.
    • Output Transform [--outputTransform] : Registration 3D transforms concatenated in a single output file. There are no tools that can use this, but can be used for debugging purposes.

  • Registration Parameters
    • Eddy Current Correction [--eddyCurrentCorrection] : Flag to perform eddy current corection in addition to motion correction (recommended) Default value: 0
    • Number Of Iterations [--numberOfIterations] : Number of iterations in each 3D fit Default value: 1000
    • Number Of Samples [--numberOfSpatialSamples] : Number of voxels sampled for mutual information computation in each 3D fit step Default value: 100000
    • Relaxation Factor [--relaxationFactor] : Fraction of gradient from Jacobian to attempt to move in each 3D fit step (adjust when eddyCurrentCorrection is enabled; suggested value = 0.25) Default value: 0.5
    • Maximum Step Size [--maximumStepSize] : Maximum permitted step size to move in each 3D fit step (adjust when eddyCurrentCorrection is enabled; suggested value = 0.1) Default value: 0.2
    • Minimum Step Size [--minimumStepSize] : Minimum required step size to move in each 3D fit step without converging -- decrease this to make the fit more exacting Default value: 0.0001
    • Translation Scale [--spatialScale] : How much to scale up changes in position compared to unit rotational changes in radians -- decrease this to put more rotation in the fit Default value: 1000.0
    • B0 Only Registration [--registerB0Only] : Register the B0 images only Default value: 0
    • Debug option [----debugLevel] : Display debug messages, and produce debug intermediate results. 0=OFF, 1=Minimal, 10=Maximum debugging. Default value: 0

User Interface


Notes from the Developer(s)

Algorithms used, library classes depended upon, use cases, etc.


Other modules or packages that are required for this module's use.


On the Dashboard, these tests verify that the module is working on various platforms:

Known bugs

Links to known bugs in the Slicer3 bug tracker

Usability issues

Follow this link to the Slicer3 bug tracker. Please select the usability issue category when browsing or contributing.

Source code & documentation

Links to the module's source code:

Source code:

Doxygen documentation:

More Information


Funding for this version of the GTRACT program was provided by NIH/NINDS R01NS050568-01A2S1


Publications related to this module go here. Links to pdfs would be useful.