Introduction to FreeSurfer Output DRAFT

Introduction to FreeSurfer Output

Exercise 1

Difficulty: Beginner

Goal: Practice basic Freeview tasks.

In the examples above you looked at data from a subject called “good_output”. For this challenge complete the following tasks for subject “004”.

1. Open the subject’s aparc+aseg.mgz volume with a colormap of “lut”.
2. Swap the view to sagittal
3. Navigate with the arrow keys to find the right putamen

Need a hint?

• Here is how you opened up a similar volume for the “good_output” subject:  freeview -v good_output/mri/aseg.mgz:colormap=lut 

• Please note that we were in the $TUTORIAL_DATA/buckner_data/tutorial_subjs directory when we used that command - so  cd  there if you'd like to base your command off the above example.

Want to know the answer? Click and drag to highlight and reveal the text below.

Exercise 2

Difficulty: Beginner

Goal: Practice visualizing data with overlays.

1. Open 004’s lh.pial surface, with the overlay named lh.thickness, set the overlay to display with a threshold of 1,2
2. Look up vertex 141813
3. What is the thickness and label of this vertex?

Need a hint?

• Here is how you opened up a similar surface for the good_output subject, with thickness information:  freeview -f good_output/surf/lh.inflated:overlay=lh.thickness:overlay_threshold=0.1,3 --viewport 3d 

• And here is how you opened up a similar surface for the good_output subject with the Desikan-Killany parcellation:  freeview -f  good_output/surf/lh.pial:annot=aparc.annot 

• Please note that we were in the $TUTORIAL_DATA/buckner_data/tutorial_subjs directory when we used that command - so  cd  there if you'd like to base your command off the above example.

Want to know the answer? Click and drag to highlight and reveal the text below.

Exercise 3

Difficulty: Beginner

Goal: Practice opening multiple files at a time with FreeView.

• For this challenge start with this terminal command:

 freeview -v 004/mri/wm.mgz:colormap=jet 004/mri/brainmask.mgz -f 004/surf/lh.pial:edgecolor=blue 004/surf/lh.white:edgecolor=red 

• Right now it only opens the left hemisphere pial and white matter surfaces, alter it to open both for the right hemisphere as well, with colors that match the left hemisphere side.
• Once you have the last command working, rearrange the volume layers in freesurfer so that the wm.mgz is at %20 opacity and the brainmask can be seen underneath it (this can also be done through altering the terminal command - you can choose which way to do so).
• You will need to be in $TUTORIAL_DATA/buckner_data/tutorial_subjs for the command to work, so cd there if needed

Want the solution? Click and drag to highlight and reveal the text below.

Exercise 4

Difficulty: Intermediate - assumes some comfort with navigating Unix and FreeView

Goal: Export a series of images from FreeView and stitch them together to create a GIF.

1. Open up any surface from the tutorial data

2. Set the viewport to 3d view, right click in the viewport and select  Hide All Slices 

3. In the  File  menu, select  Save Movie Frames 

4. Set up the options as in the following picture - you will likely want to create a new directory in your home directory to save the output to.

5. In a terminal, navigate to the new directory you output the movie data to.

6. Run this command:  convert -delay .1 *.png brainanim.gif 

   • Note: convert is from the ImageMagick library, which is a prerequesite for running FreeView.

   •  -delay  determines the gap between frames,  *.png  selects all png files in the working directory,  brainanim.gif  is the output name.

7. To view your GIF, open it with firefox  firefox brainanim.gif 

Practice Working With Data

Exercise 1

Difficulty: Beginner

Goal: Prepare a dicom series for the recon-all stream

Your goal is to set up your environment variables and assemble the correct recon-all command to process a dicom series.

To begin navigate to the following directory in your terminal:  $TUTORIAL_DATA/practice_with_dicoms 

Take a look at the directories found there. The  dicoms  directory contains a dicom series, and the  subjects  directory is where your recon-all subject output should go. You will want to use dcmunpack to find the first image of the first T1w_MPR_vNav_4eRMS series, set your SUBJECT_DIR environment variable, then then type out and run your recon-all command (use practice_subject as the subject name). Make sure the command starts without any errors - and if it does cancel the process by pressing ctrl and c on the keyboard (a recon-all can take many hours!).

Check in the  work  directory to ensure a directory with your subject's name was created (practice_subject), if you see the folder you have completed the challenge!

Hints:

• Follow the tutorial example for guidance
• It might be tricky to find the path to the subjects directory if you are new to Unix, you can use this: $TUTORIAL_DATA/practice_with_dicoms/subjects

Want to see the answer? Highlight the lines below