|
Size: 3176
Comment:
|
Size: 3652
Comment:
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 1: | Line 1: |
| [wiki:Self:FsTutorial top] | [wiki:Self:FsTutorial/MorphAndRecon previous] | [wiki:Self:FsTutorial top] | [wiki:Self:FsTutorial/TroubleshootingData previous] = Correcting Pial Surfaces = *To follow this exercise exactly be sure you've downloaded the [wiki:Self:FsTutorial/Data tutorial data set] before you begin. If you choose not to download the data set you can follow these instructions on your own data, but you will have to substitute your own specific paths and subject names. |
| Line 3: | Line 5: |
| == Correcting Pial Surfaces == | The pial surface is created by expanding the white matter surface so that it closely follows the gray-CSF intensity gradient as found in the brainmask.mgz volume. Once an accurate white surface is created then you can work on correcting the pial surface if needed. The pial surface boundary and white matter surface boundary should not cross. After the pial surface has been generated, it's a good idea to visually check it for defects that may have been created during automatic topology fixing. To check the pial surface, it may be loaded into tkmedit and viewed along with the brainmask.mgz volume. If the surface appears not to follow the gray-CSF boundary in the volume, edits may be required. |
| Line 5: | Line 7: |
| The pial surface is created by expanding the white matter surface so that it closely follows the gray-CSF intensity gradient as found in the brain volume. Once an accurate white surface is created then you can work on correcting the pial surface if needed. The pial surface boundary and white matter surface boundary should not cross. After the pial surface has been generated, it's a good idea to visually check it for defects that may have been created during automatic topology fixing. To check the pial surface, it may be loaded into tkmedit and viewed along with the BRAIN volume. If the surface appears not to follow the grey-CSF boundary in the volume, edits may be required. | == Editing the Volume == Subject 3 is an example of the pial surface including non-cortex within the boundaries. This page will take you through fixing this and other similar problems with the pial surface including non-cortex material. |
| Line 7: | Line 10: |
| '''Editing the Volume'''[[BR]] Before you begin editing, you will want to set your SUBJECTS_DIR environment variable to the correct path: |
First, make sure you have subject3_before loaded in tkmedit: |
| Line 11: | Line 13: |
| cd $FREESURFER_HOME/subjects/buckner_data/tutorial_subjs setenv SUBJECTS_DIR ${PWD} |
tkmedit subject3_before brainmask.mgz lh.white -aux-surface rh.white |
| Line 15: | Line 16: |
| Open the brain and T1 volumes simultaneously in tkmedit: | Use the arrow keys to go through the volume slice by slice, and view the pial surface (red line) and white matter surface (yellow line). Notice the bright diagonal line in slice 161 that has caused the pial surface to expand past the actual pial boundary. This is the result of a bad segmentation incorporating a piece of the dura within the pial surface. |
| Line 17: | Line 18: |
| {{{ tkmedit 108_brain_pial_edits_before brain.mgz -aux T1.mgz }}} In tkmedit, go to '''File -> Load Main Surface...''' Click the Browse button, and then select the file named lh.orig. Use the arrow keys to go through the volume slice by slice, and view the pial surface (red line) and white matter surface (green line). Notice the bright diagonal line in slice 161 that has caused the pial surface to expand past the actual pial boundary. This is the result of a bad segmentation due to a blood vessel. |
attachment:subject3_beforePIALdura.jpg |
| Line 23: | Line 20: |
| attachment:sj108.c161.brain.vessel.before.jpg | To fix this type of error you can simply edit away the offending voxels from the brainmask.mgz volume. To do this you will need to select the edit voxels tool and set the brush to a size and shape comfortable for you. A circle brush of radius 2 works well for this edit. In the tkmedit toolbar, go to '''Tools -> Configure Brush Info...''' Set Radius to 2, and Shape to "Circle". Close the configuration menu, and click the "Edit Voxels" button in tkmedit toolbar. |
| Line 25: | Line 22: |
| In the tkmedit toolbar, go to: | Find a place in the image where the dura is causing errors in the segmentation. Use the right mouse button to delete the voxels. It is not necessary to completely remove the dura to get an adequate pial surface, but it is good to do so until you are more familiar with manual editing. When you are finished removing the bright diagonal line in slice 161, it should look like this: |
| Line 27: | Line 24: |
| '''Tools -> Configure Brush Info...''' | attachment:subject3_afterPIAL.jpg |
| Line 29: | Line 26: |
| Set Radius to 2, and Shape to "Circle". | Continue on the other slices until the blood vessel is removed. Save your volume as pial-brain.mgz. |
| Line 31: | Line 28: |
| Close the configuration menu, and click the "Edit Voxels" button in tkmedit toolbar. | Ctrl-z and '''Edit -> Undo Last Edit''' in tkmedit only allow you to go back one edit. If you remove too many voxels, you can use the clone tool to paint areas back in from the original T1 volume, similar to painting in voxels in section 1.1. |
| Line 33: | Line 30: |
| Find a place in the image where the blood vessel is causing errors in the segmentation. Use the right mouse button to delete the voxels, like in the [wiki:Self/FsTutorial/SkullStripTutorial skull stripping tutorial]. It is not necessary to completely remove the blood vessel to get an adequate pial surface, but it is good to do so until you are more familiar with manual editing. When you are finished removing the bright diagonal line in slice 161, it should look like this: | You can check your result by viewing the brain.mgz volume in the 108_after directory. |
| Line 35: | Line 32: |
| attachment:sj108.c161.brain.vessel.after.jpg Continue on the other slices until the blood vessel is removed. Save your volume as pial-brain.mgz. Ctrl-z and '''Edit -> Undo Last Edit''' in tkmedit only allow you to go back one edit. If you remove too many voxels, you can use the clone tool to paint areas back in from the original T1 volume, similar to painting in voxels in section 1.1. You can check your result by viewing the brain.mgz volume in the 108_after directory. '''Regenerating the Surface'''[[BR]] |
== Regenerating the Surface == |
| Line 47: | Line 36: |
| recon-all -autorecon2-pial -subjid 108_brain_pial_edits_before | recon-all -autorecon2-pial -autorecon3 -subjid subject3_before |
| Line 49: | Line 38: |
This step will take a long time and there is no need to run it for the tutorial purposes. |
[wiki:FsTutorial top] | [wiki:FsTutorial/TroubleshootingData previous]
Correcting Pial Surfaces
To follow this exercise exactly be sure you've downloaded the [wiki:FsTutorial/Data tutorial data set] before you begin. If you choose not to download the data set you can follow these instructions on your own data, but you will have to substitute your own specific paths and subject names.
The pial surface is created by expanding the white matter surface so that it closely follows the gray-CSF intensity gradient as found in the brainmask.mgz volume. Once an accurate white surface is created then you can work on correcting the pial surface if needed. The pial surface boundary and white matter surface boundary should not cross. After the pial surface has been generated, it's a good idea to visually check it for defects that may have been created during automatic topology fixing. To check the pial surface, it may be loaded into tkmedit and viewed along with the brainmask.mgz volume. If the surface appears not to follow the gray-CSF boundary in the volume, edits may be required.
Editing the Volume
Subject 3 is an example of the pial surface including non-cortex within the boundaries. This page will take you through fixing this and other similar problems with the pial surface including non-cortex material.
First, make sure you have subject3_before loaded in tkmedit:
tkmedit subject3_before brainmask.mgz lh.white -aux-surface rh.white
Use the arrow keys to go through the volume slice by slice, and view the pial surface (red line) and white matter surface (yellow line). Notice the bright diagonal line in slice 161 that has caused the pial surface to expand past the actual pial boundary. This is the result of a bad segmentation incorporating a piece of the dura within the pial surface.
attachment:subject3_beforePIALdura.jpg
To fix this type of error you can simply edit away the offending voxels from the brainmask.mgz volume. To do this you will need to select the edit voxels tool and set the brush to a size and shape comfortable for you. A circle brush of radius 2 works well for this edit. In the tkmedit toolbar, go to Tools -> Configure Brush Info... Set Radius to 2, and Shape to "Circle". Close the configuration menu, and click the "Edit Voxels" button in tkmedit toolbar.
Find a place in the image where the dura is causing errors in the segmentation. Use the right mouse button to delete the voxels. It is not necessary to completely remove the dura to get an adequate pial surface, but it is good to do so until you are more familiar with manual editing. When you are finished removing the bright diagonal line in slice 161, it should look like this:
attachment:subject3_afterPIAL.jpg
Continue on the other slices until the blood vessel is removed. Save your volume as pial-brain.mgz.
Ctrl-z and Edit -> Undo Last Edit in tkmedit only allow you to go back one edit. If you remove too many voxels, you can use the clone tool to paint areas back in from the original T1 volume, similar to painting in voxels in section 1.1.
You can check your result by viewing the brain.mgz volume in the 108_after directory.
Regenerating the Surface
When you are finished editing the voxels, you will need to regenerate the surfaces. Since the white matter hasn't been changed, you don't need to resegment the volume. You can regenerate the pial surface with:
recon-all -autorecon2-pial -autorecon3 -subjid subject3_before
This step will take a long time and there is no need to run it for the tutorial purposes.