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| Below is a list of common things that require manual intervention (some more common than others). As you move through this exercise there will be links to pages instructing you how to fix these problems. While you are trying to identify the problems with the subjects listed below you may find it helpful to refer back to the [[FsTutorial/OutputData|previous exercise]], or open your own instance of the subject good_output to compare these subjects to a good example. | Below, we ask you to look at several subjects with various errors that require manual intervention. Open each subject and try to identify the problem on your own. For each subject, there is a link to instructions on how to fix the problem. While you are trying to identify the problems with the subjects listed below you may find it helpful to refer back to the [[FsTutorial/OutputData|previous exercise]], or open your own instance of the subject good_output to compare these subjects to a good example. |
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== Correcting topological defects == Open the subject, '''topo_defect_before''', in tkmedit. |
== Edits to the brainmask volume == Open the subject, '''pial_edits_before'''. |
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tkmedit topo_defect_before brainmask.mgz \ lh.white -aux wm.mgz -aux-surface rh.white |
tkmedit pial_edits_before brainmask.mgz \ lh.white -aux T1.mgz -aux-surface rh.white |
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| This will open the brainmask.mgz volume, the wm.mgz loaded as aux, and the surfaces for both hemispheres. (You can feel free to open other volumes in aux or to load in the aseg.mgz if you want or need to.) | The command above will open the brainmask.mgz volume, the T1.mgz loaded as aux, and the surfaces for both hemispheres. (You can feel free to open other volumes in aux or to load in the aseg.mgz if you want or need to.) Scroll through the slices of this subject to check the pial and white surfaces for accuracy, making sure they follow the actual gray/white boundaries and that they do not include anything that should not be included. |
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| Take a look at this subject, inspecting the various outputs that were mentioned in the [[FsTutorial/OutputData|previous exercise]] and see if you can identify what is wrong. | |
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| Once you spot the error, click [[FsTutorial/TopologicalDefect|here]] for detailed instructions on how you can fix it. After you have fixed it, you can compare the original data to the finished version, '''topo_defect_after'''. To view this corrected subject (which was corrected by following the detailed instructions provided to you): | If you would like to see the inflated surfaces for each hemisphere of this subject, in a second and third terminal window, open the surfaces in tksurfer: |
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tkmedit topo_defect_after brainmask.mgz \ lh.white -aux wm.mgz -aux-surface rh.white |
tksurfer pial_edits_before lh inflated |
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---- {{{ tksurfer pial_edits_before rh inflated }}} ---- Once you have identified the problem (or have given up!), click [[FsTutorial/PialEdits|here]] for detailed instructions on how you can fix it. |
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| You may need to open other volumes in order to see or fix the problem. | Click [[FsTutorial/WhiteMatterEdits|here]] for detailed instructions on how you can fix it. You can also compare the original data to a corrected and rerun version, '''wm1_edits_after'''. |
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Click [[FsTutorial/WhiteMatterEdits|here]] for detailed instructions on how you can fix it. You can also compare this to the finished version, wm1_edits_after. == Edits to the brainmask volume == Now, take a look at the next subject, '''pial_edits_before'''. |
To view this corrected subject (which was corrected by following the detailed instructions provided to you): |
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tkmedit pial_edits_before brainmask.mgz \ lh.white -aux T1.mgz -aux-surface rh.white |
tkmedit wm1_edits_after brainmask.mgz \ lh.white -aux wm.mgz -aux-surface rh.white |
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| Again, this will bring up the brainmask.mgz volume, the T1.mgz volume, and the surfaces for both hemispheres. | |
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| In a second and third terminal window, if not already open, open the surfaces in tksurfer: |
== Correcting topological defects == Open the subject, '''topo_defect_before''', in tkmedit. |
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| tksurfer pial_edits_before lh inflated |
tkmedit topo_defect_before brainmask.mgz \ lh.white -aux wm.mgz -aux-surface rh.white |
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This will open the brainmask.mgz volume, the wm.mgz loaded as aux, and the surfaces for both hemispheres. Take a look at this subject, inspecting the various outputs that were mentioned in the [[FsTutorial/OutputData|previous exercise]] and see if you can identify what is wrong. ''Hint: It's a very small error in the posterior part of the brain.'' Once you spot the error, click [[FsTutorial/TopologicalDefect|here]] for detailed instructions on how you can fix it. After you have fixed it, you can compare the original data to the a corrected and rerun version, '''topo_defect_after'''. To view this corrected subject: |
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| tksurfer pial_edits_before rh inflated |
tkmedit topo_defect_after brainmask.mgz \ lh.white -aux wm.mgz -aux-surface rh.white |
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This will open the inflated surfaces for both hemispheres in tksurfer. The trouble with this subject has occurred while making the final surfaces. Check the final surfaces (pial and white surfaces) in the volume to make sure that they follow the actual gray/white and boundaries and that they do not include anything that should not be included. You may need to open other volumes in order to see or fix the problem. Click [[FsTutorial/PialEdits|here]] for detailed instructions on how you can fix it. |
Troubleshooting your output
This set of exercises will take you through a few examples of problem outputs, asking you to identify the problems and possible methods to fix the problems. Each example will have a before and after picture, as well as an explanation of how to fix the problems seen.
If you are taking one of the formally organized courses, the data is already installed on the computer provided to you so please skip ahead to the Failure Modes section. If not, then to follow this exercise exactly be sure you've downloaded the tutorial data set before you begin. This set of exercises is not possible without the tutorial data set. Please set the environmental variable TUTORIAL_DATA to the location that you have downloaded the data to (here, it has been copied to $FREESURFER_HOME/subjects):
tcsh setenv TUTORIAL_DATA $FREESURFER_HOME/subjects/buckner_data/tutorial_subjs
- Notice the command to open tcsh. If you are already running the tcsh command shell, then the 'tcsh' command is not necessary.
First make sure you have your SUBJECTS_DIR set to the correct location:
tcsh setenv SUBJECTS_DIR $TUTORIAL_DATA cd $SUBJECTS_DIR
Failure Modes
Below, we ask you to look at several subjects with various errors that require manual intervention. Open each subject and try to identify the problem on your own. For each subject, there is a link to instructions on how to fix the problem. While you are trying to identify the problems with the subjects listed below you may find it helpful to refer back to the previous exercise, or open your own instance of the subject good_output to compare these subjects to a good example.
Edits to the brainmask volume
Open the subject, pial_edits_before.
tkmedit pial_edits_before brainmask.mgz \ lh.white -aux T1.mgz -aux-surface rh.white
The command above will open the brainmask.mgz volume, the T1.mgz loaded as aux, and the surfaces for both hemispheres. (You can feel free to open other volumes in aux or to load in the aseg.mgz if you want or need to.) Scroll through the slices of this subject to check the pial and white surfaces for accuracy, making sure they follow the actual gray/white boundaries and that they do not include anything that should not be included.
If you would like to see the inflated surfaces for each hemisphere of this subject, in a second and third terminal window, open the surfaces in tksurfer:
tksurfer pial_edits_before lh inflated
tksurfer pial_edits_before rh inflated
Once you have identified the problem (or have given up!), click here for detailed instructions on how you can fix it.
Edits to the wm volume
Now, take a look at the next subject, wm1_edits_before.
tkmedit wm1_edits_before brainmask.mgz \ lh.white -aux T1.mgz -aux-surface rh.white
Again, this will bring up the brainmask.mgz volume, the T1.mgz volume, and the surfaces for both hemispheres.
In your second and third terminal window, if not already open, open the surfaces in tksurfer:
tksurfer wm1_edits_before lh inflated
tksurfer wm1_edits_before rh inflated
This will open the inflated surfaces for both hemispheres in tksurfer.
The trouble with this subject has occurred during the white matter segmentation step. Check the surfaces in the T1 volume to find the spot that does not match the actual gray/white boundary. If you load the wm.mgz volume as the aux volume you will see a hole in this area. If you are looking in tksurfer you will see a hole or dimple in the inflated surface. You can use the "save point" "goto point" commands to find this spot in the volume.
Click here for detailed instructions on how you can fix it. You can also compare the original data to a corrected and rerun version, wm1_edits_after.
To view this corrected subject (which was corrected by following the detailed instructions provided to you):
tkmedit wm1_edits_after brainmask.mgz \ lh.white -aux wm.mgz -aux-surface rh.white
Correcting topological defects
Open the subject, topo_defect_before, in tkmedit.
tkmedit topo_defect_before brainmask.mgz \ lh.white -aux wm.mgz -aux-surface rh.white
This will open the brainmask.mgz volume, the wm.mgz loaded as aux, and the surfaces for both hemispheres.
Take a look at this subject, inspecting the various outputs that were mentioned in the previous exercise and see if you can identify what is wrong.
Hint: It's a very small error in the posterior part of the brain.
Once you spot the error, click here for detailed instructions on how you can fix it. After you have fixed it, you can compare the original data to the a corrected and rerun version, topo_defect_after. To view this corrected subject:
tkmedit topo_defect_after brainmask.mgz \ lh.white -aux wm.mgz -aux-surface rh.white
Skull strip
Now, take a look at the next subject, skullstrip1_before, in tkmedit.
tkmedit skullstrip1_before brainmask.mgz \ lh.white -aux T1.mgz -aux-surface rh.white
This will open the brainmask.mgz volume, the T1.mgz loaded as aux, and the surfaces for both hemispheres.
The trouble with this subject has occurred in the skull stripping step. Check the brainmask.mgz volume carefully, comparing it to the T1.mgz volume (loaded in aux) to make sure that the skull has been completely stripped away, leaving behind the complete cortex and the cerebellum.
You can feel free to open other volumes in aux or to load in the aseg.mgz if you want or need to.
Click here for detailed instructions on how you can fix it. You can also compare this to the finished version, skullstrip1_after.
Adding control points
Now, take a look at the next subject, cp_before.
tkmedit cp_before brainmask.mgz \ lh.white -aux T1.mgz -aux-surface rh.white
Again, this will bring up the brainmask.mgz volume, the T1.mgz volume, and the surfaces for both hemispheres.
In your second terminal window, if not already open, open the surfaces in tksurfer:
tksurfer cp_before lh inflated & tksurfer cp_before rh inflated &
This will open the inflated surfaces for both hemispheres in tksurfer.
The trouble with this subject has occured during the intensity normalization. Check the white surface and be sure it is including all of the white matter as it should. If you find an area that is not included as white matter be sure to check to see that the intensity is at (or very close to) 110.
You may need to open other volumes in order to see or fix the problem.
Click here for detailed instructions on how you can fix it.
Talairach transformation
Now, take a look at the next subject, tal_before.
tkmedit tal_before brainmask.mgz \ lh.white -aux T1.mgz -aux-surface rh.white
Again, this will bring up the brainmask.mgz volume and the T1.mgz volume and the surfaces for both hemispheres.
In a second and third terminal window, if not already open, open the surfaces in tksurfer:
tksurfer tal_before lh inflated
tksurfer tal_before rh inflated
This will open the inflated surfaces for both hemispheres in tksurfer.
The trouble with this subject is a little tricky to figure out. The midline cutting planes are not actually on the midline, but the real root of this problem is in one of the very initial steps of recon-all. The talairach transform is bad and will need to be fixed.
You may need to open other volumes in order to see or fix the problem.
Click here for detailed instructions on how you can fix it.
Editing the Aseg
We generally advise against editing the aseg.mgz unless absolutely necessary. Try using an xopts script first to change the intensity thresholds being used. Editing the aseg will add more variance to your data. Instructions on how to edit the aseg are here.