[FieldTrip] Using ft_volumerealign with narrow FOV

[Schoffelen, J.M. (Jan Mathijs)]

Hi Pin-Chun

Just to be sure: it’s not the ’tip of the nose’ that needs to be visible, but the ’nasion’ which is the point at the lower end of the forehead where the nose starts protruding from the face. This of course is based on the assumption that the respective MEG measurements are using this landmark as the one defining the head coordinate system.

If the FOV of the MRI is even too narrow for that, there’s not much you could do. The only thing worth considering is a (suboptimal) linear registration of the small FOV image to a template MRI image (that contains a decent head contour) and warp back the nasion position from the template into single subject space. But, as I said, this will be inaccurate.

Best wishes,
Jan-Mathijs


On 15 May 2024, at 15:40, Pin-Chun Chen via fieldtrip <fieldtrip at science.ru.nl<mailto:fieldtrip at science.ru.nl>> wrote:

Dear FieldTrip community,

I’m using the ft_volumerealign function for source localizing a MEG dataset.
However, the T1 structure scan does not have a wide FOV that include the tip of the nose for some participants.

Does anyone have experience aligning the LPA/RPA/Nasion to MEG data with a narrow FOV?

Here are the scripts I’m using:

mri = ft_read_mri(mrifilename);

cfg                        =  [];
cfg.method      = 'interactive';
cfg.coordsys    = 'neuromag';
rmri                      =  ft_volumerealign(cfg,mri);

Thank you,
PinChun


--

Pin-Chun Chen, PhD
Marie Curie Postdoctoral Fellow
Department of Experimental Psychology
University of Oxford

This is a Taiwanese name. First name is ‘Pin-Chun’ altogether, surname is ‘Chen’. There is no middle name.

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