Step 24/24. For more information, click on the Help tab. The blue link will send you to this page:
- Input Image: input image
- Mask Image: label map providing an approximative segmentation of the ROI
- Output Volume: corrected image
Step 24/24. Click on the Help tab
Cheat Sheet
- Load the input dataset (Main menu: Add Volume)
- Create a Mask Volume using the Editor (Modules > Editor) (the Threshold tool should give a good result)
- Select the MRIBiasFieldCorrection module (Modules > Filtering > MRIBiasFieldCorrection)
- In the left panel, select the Input Volume
- Select the Mask Volume
- In the Preview Volume menu , select 'Create New Volume'
- Do the same for the Output Volume menu
- Modify the parameter values if desired (default values gave good results during our experiments)
- Click on Apply.
Close-up of the above screenshot showing the image before and after correction. Note that the intensity inhomogeneity visible in the input image (left) has been corrected in the output image (right).
It took 32 min to process a 512x512x30 MRI volume on a MacBook laptop. To visualize the result:
- Deselect the Overlay volume,
- Select the input as Background volume and the output as Foreground volume.
- Go to Modules > Volumes
- Select the input volume, and write down the values for Window and Level
- Select the output volume, and apply the same values
- Move the lower left cursor in 'Manipulate Slice Views' between B (background) and F (foreground)
Tests
On the Dashboard, these tests verify that the module is working on various platforms:
- MyModuleTest1 MyModuleTest1.cxx
- MyModuleTest2 MyModuleTest2.cxx
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:
More Information
Acknowledgment
This work is part of the National Alliance for Medical Image Computing (NAMIC), funded by the National Institutes of Health through the NIH Roadmap for Medical Research, Grant U54 EB005149 (PI: Ron Kikinis).
References for algorithms implemented in this module
- A Nonparametric Method for Automatic Correction of Intensity Nonuniformity in MRI Data, J.G. Sled, A.P. Zijdenbos, and A.C. Evans, IEEE Transactions on Medical Imaging, 17(1):87–97, Feb 1998.
- N4ITK: Improved N3 Bias Correction, N.J. Tustison, B.B. Avants, P.A. Cook, Y. Zheng, A. Egan, P.A. Yushkevich, J.C. Gee, IEEE Transactions on Medical Imaging, Vol 99, April 2010.
- N4ITK: Nick's N3 ITK Implementation for MRI Bias Field Correction, N. Tustison, J. Gee, Insight Journal, 2009.
References for related algorithms
- Parametric Estimate of Intensity Inhomogeneities Applied to MRI, M. Styner, C. Brechbhuler, G. Szekely, and G. Gerig, IEEE Transactions on Medical Imaging, 19(3):153–165, Mar 2000.