Coregistration

Discussions
1

Hi to all,

I have the following question.
I used electa MEG system
I have the MRI and the polhemus data for each subject.
The MRI are in dicom and I can also transform it to ‘analyze’ format using SPM.
The polhemus data are in fif format, together with the functional data.
How can I coregister these two types of data?

A step by step (AC-PC points, normalization, segmentation etc) guidance would be very helpful stating the functions I have to use and any precautions I have to consider during this process.

Best regards and thanks in advance,

Haris Styliadis

2

Dear Haris,

You can import and co-register easily the data you cite with Brainstorm:

  1. A MRI in Analyze or Nifti format (many common software packages can convert from DICOM to those formats: SPM, FreeSurfer, BrainVISA, MRICro…)
  2. A cortex and head surface extracted from the MRI volume using a program of your choice: FreeSurfer, BrainVISA, BrainSuite… See here for an example: http://neuroimage.usc.edu/brainstorm/Tutorials/SegBrainVisa
  3. Your .fif file that contains the MEG recordings and the head points digitized with the Polhemus

You will find under the Tutorial section of the Brainstorm website all the information you need to complete all those tasks, and the explanations on how the co-registration is performed.
http://neuroimage.usc.edu/brainstorm/Tutorials

I would recommend you to start by reading (and following step by step) the introduction tutorials (at least from 1 to 9), so that you understand who the different types of data are handled by the software. They are based on CTF MEG data and not Elekta Neuromag, but the logic is exactly the same.
Then, when you are familiar with the Brainstorm interface and the processing of MEG data, you can move on to two advanced tutorials, under the section “Exploring Continuous Recordings”, that will show how to explore and process continuous Neuromag data in FIF format.

If what you need is scripting those operations instead of using the interface, you will find many example Matlab scripts in the brainstorm3/toolbox/script folder, that follow exactly the online tutorials step by step.

Enjoy!
Francois