Head Model Computation using BEM

[EthanY]

Hello,

I’m attempting to compute the head model for a subject using OpenMEEG BEM, as I’ve successfully done for several other subjects. However, the computation is getting stuck at the "Reading SEEG leadfield" step. The relevant MATLAB error messages are attached below.

I encountered similar issues with two other subjects previously, which were due to electrode misalignment and were resolved after recalibration. In this subject, the electrodes appear properly aligned, yet the problem persists.

![Image 2025-07-24 at 11.13 AM (1)|690x294, 75%]

Thank you for your help in advance!

[EthanY]

[tmedani]

Hi @EthanY

Can you try to run the BEM on another subject, with different anatomy and channel file?

It seems something is wrong with the data.

[Raymundo.Cassani]

@EthanY, it seems there is an issue with the location of one SEEG channel.

• Are you sure all the SEEG electrode have location?
• Can you share the channel file that you use to compute the head model?

[EthanY]

Hi @tmedani,

I have successfully run the BEM on other subjects using the same process, but with different anatomy and channel files before.

[EthanY]

Hi @Raymundo.Cassani,

• Yes, all the SEEG electrodes have locations.
• Here is the channel file I used, attached below.

S24-217.pos (11.2 KB)

[Raymundo.Cassani]

@EthanY, please share the Brainstorm channel file.

Right-click on the Channel file (), then File > Copy file path to clipboard.
That will give you the absolute path for the file to share with us

[EthanY]

Thank you for the tip. Here is the file attached.
channel.mat (14.4 KB)

[tmedani]

Thanks for sharing @EthanY and for comfirming that is working with other subjects.

@Raymundo.Cassani the channel file looks correct to me.
there are 138 SEEG channels with all existing positions.

I believe something went wrong with OpenMEEG computation.

@EthanY can you try again with the same subject and see if the same error appears.

[tmedani]

@EthanY Could you check visually and share some views of the BEM surfaces that you used for the computation?

[EthanY]

@Raymundo.Cassani, I have tried to rerun the same subject and had the same errors. I have also tried to regenerate the BEM surfaces but still encounter the same errors, and the surfaces look about the same as before. The BEM surfaces I used are attached below.

[Raymundo.Cassani]

Do you get any other message in the command window before the error is printed?

Would it be possible to also share the anatomy files for that subject to test on our side?
(At this point, the easiest way to share is to export the entire Subject, right-click on the subject node, then File > Export Subject)

[tmedani]

@EthanY Thanks for sharing your views.

What is this bump is the left side?

Are you using all three 3 surfaces for the BEM computation?

Can you try running the BEM within only the inner and outer skull?