DBP2:UNC:Regional Cortical Thickness Pipeline

Back to UNC Cortical Thickness Roadmap

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Objective

We would like to create an end-to-end application within Slicer3 allowing individual and group analysis of regional cortical thickness.

This page describes the related pipeline with its basic components, as well as its validation.

Pipeline overview

A Slicer3 high-level module for individual cortical thickness analysis has been developed: ARCTIC (Automatic Regional Cortical ThICkness)

Input: RAW images (T1-weighted, T2-weighted, PD-weighted images)

• 1. Tissue segmentation
  • Probabilistic atlas-based automatic tissue segmentation via an Expectation-Maximization scheme
  • Tool: itkEMS (UNC Slicer3 external module)
• 2. Regional atlas deformable registration
  • 2.1 Skull stripping using previously computed tissue segmentation label image
    • Tool: SegPostProcess (UNC Slicer3 external module)
  • 2.2 T1-weighted atlas deformable registration
    • B-spline pipeline registration
    • Tool: RegisterImages (Slicer3 module)
  • 2.3. Applying transformation to the parcellation map
    • Tool: ResampleVolume2 (Slicer3 module)
• 3. Cortical Thickness
  • Sparse asymmetric local cortical thickness
  • Tool: CortThick (UNC Slicer3 external module)
• 4. Statistics
  • Generate spreesheats with volume informations
  • Tools: ImageMath, ImageStat (UNC Slicer3 external modules)
• 5. Mesh Creation
  • Generation of white matter and grey matter meshes
  • Tool: ModelMaker (Slicer3 module)
• 6. MRML scene creation
  • Creation of a MRML scene describing all the steps of the pipeline

All the tools used in the current pipeline are Slicer3 modules, some of them being UNC external modules. The user can thus compute an individual regional cortical thickness analysis by running the 'ARCTIC' module, either within Slicer3 or as a command line.

Download

Source code available with CVS

• Create and go to a NeuroLib/ directory

 mkdir NeuroLib
 cd NeuroLib

• Make the following commands :

 cvs -d :pserver:anonymous@demeter.ia.unc.edu:/cvsroot login (press Enter for password)
 cvs -d :pserver:anonymous@demeter.ia.unc.edu:/cvsroot co NeuroLib

• Be sure that the 2.6 version of CMake is installed on your computer. ‏If not download it here
• Create and go to a Neurolib-build/ directory

 mkdir NeuroLib-build
 cd NeuroLib-build

• Start the compilation while launching 'ccmake'

 ccmake ../NeuroLib

• Configure the compilation

 Set ARCTIC at "ON"
 Press 'c' to start the configuration

Executables and tutorial dataset

Available on NITRC : http://www.nitrc.org/projects/arctic/

Pediatric atlas

Available on MIDAS : http://www.insight-journal.org/midas/item/view/2277

Tutorials

• ARCTIC tutorial : end-to-end Slicer3 module to perform automatic regional cortical thickness analysis‏ [ppt]‏ [pdf]

• UNC Modules tutorial : UNC Slicer3 modules to perform regional cortical thickness analysis step by step [ppt]‏ [pdf]‏

T1-weighted skull-stripped image

Parcellation image

Cortical thickness on WM surface

Cortical thickness information

ARCTIC (Automatic Regional Cortical ThICkness) usage:

Prerequities

Add directories to the PATH variable

 -tcsh usage : setenv PATH ARCTIC-Executables-Directory:Slicer3D-Plugins-Directory:Batchmake-Directory:${PATH}
 -bash usage : export PATH=ARCTIC-Executables-Directory:Slicer3D-Plugins-Directory:Batchmake-Directory:${PATH}
 Notice : To execute ARCTIC within Slicer3D, it is not necessary to add "Slicer3D-Plugins-Directory" in the PATH.

Set an environment variable

 -tcsh usage : setenv BatchmakeWrapper_Dir Batchmake-Wrapper-Directory
 -bash usage : export BatchmakeWrapper_Dir=Batchmake-Wrapper-Directory

Set ARCTIC as a Slicer3D module

 Within Slicer3D : View -> Applications Settings -> Module Settings -> Add a preset button and then select the ARCTIC-Executables-Directory/

Command line execution

Inputs: T1-weighted image, T1-weigthed atlas, regional atlas (parcellation map)

 ARCTIC --T1 Image_T1.gipl --segAtlasDir TissueSegmentationAtlasDirectory/ 
 --atlas Atlas.gipl --atlasParcellation Parcellation.gipl --SaveWM  WMCorticalThicknessMap.gipl  --SaveGM GMCorticalThicknessMap.gipl

Notice : for both flags "SaveWM" and "SaveGM", the fileName needed is a path with the name of the output volume.

Step by step command line execution

• 1. Tissue segmentation
  • Input: EMSparam.xml
  • Output: Image_Corrected_EMS.gipl, Label.gipl

 itkEMSCLP --XMLFile EMSparam.xml

• 2. Skull stripping
  • Input: Label.gipl, Image_Corrected_EMS.gipl
  • Output: Image_Corrected_EMS_Stripped.gipl, BinaryMask.gipl (optional)

 SegPostProcessCLP Label.gipl  Image_Corrected_EMS_Stripped.gipl --skullstripping  Image_Corrected_EMS.gipl

• 3. Deformable registration of pediatric regional atlas
  • 3.1 Deformable registration of T1-weighted pediatric atlas
    • Input: Atlas.gipl, Image_Corrected_EMS_Stripped.gipl
    • Output: Atlas_Registered.gipl, Atlas_Registered_Transform.txt

  RegisterImages Image_Corrected_EMS_Stripped.gipl Atlas.gipl –resampledImage  Atlas_Registered.gipl –saveTransform Atlas_Registered_Transform.txt –registration PipelineBSpline

• • 3.2. Applying transformation to the parcellation map
    • Input: Parcellation.gipl, Atlas_Registered_Transform.txt, Image_Corrected_EMS_Stripped.gipl
    • Output: Parcellation_Registered.gipl

  ResampleVolume2 Parcellation.gipl Parcellation_Registered.gipl -f Atlas_Registered_Transform.txt -i nn -R Image_Corrected_EMS_Stripped.gipl

• 4. Cortical Thickness
  • Input: Parcellation_Registered.gipl, Label.gipl
  • Output: CortThick_Result_Dir/, WMCorticalThicknessMap, GMCorticalThicknessMap

  CortThickCLP CortThick_Result_Dir/ --par  Parcellation_Registered.gipl --inputSeg Label.gipl --SaveWM  WMCorticalThicknessMap  --SaveGM GMCorticalThicknessMap

Pipeline validation

Analysis on a small pediatric dataset

Tests have been computed on a small pediatric dataset which includes 2 year-old and 4 year-old cases.

• 16 autistic cases
• 1 developmental delay
• 3 normal control

Comparison to state of the art

We would like to compare our pipeline with FreeSurfer. We have thus started to perform a regional statistical analysis using Pearson's correlation coefficient on a pediatric dataset including 90 cases.

Two distinct groups are considered: 2 year-old cases and 4 year-old cases.

Planning

Done

• Workflow for individual analysis (Slicer3 external module using BatchMake)
• 2 Tutorials with application example on a small dataset : "How to use the UNC modules to compute the regional cortical thickness" and "How to use ARCTIC"
• Pediatric atlases available to the community through MIDAS
• ARCTIC available to the community through NITRC: executables (UNC external modules for Slicer3) and Tutorial dataset
• New version including quality control through MRML scene, and WM, GM models generation

In progress

• Comparison to FreeSurfer (180 cases dataset): pearson correlation analysis
• ARCTIC source code (SVN, CVS) available to the community