I have hacked together a method to normalize LORETA current density maps
form the Curry source localization package with MR and PET image as part
of a project to do cross subject comparisons. It is not yet published,
but you are free to use it. I would also like to hear what any other
SPMers (especially John) may think of it.
The LORETA output format we get is a list of regularly spaced (10mm
lattice) points in the brain and the current magnitude at each point. I
create a binary brain mask from the points in the brain. Then I use a
linear only normalization to normalize the LORETA brain mask to the
brain mask distributed with SPM. I then apply this normalization to
each of the LORETA images.
For your purposes, I would suspect that by segmenting the MR you could
create a brain mask for each subject and normalize the subject's LORETA
to their MR.
I have some matlab and perl scripts to automate some of this if you are
using Curry. Let me know if you want them.
Hope it helps,
---sam
[log in to unmask] wrote:
>Dear M.
>
>Loreta reconstructions are far too different from morphology (low
>resolution and different principles + timing) to successfully be
>registered to MRI through SPM's paradigms. The most reasonable way to
>perform this registration is through the EEG electrodes' locations on
>the scalp (which is also visible on the MRI). Depending on what you are
>looking for, there are various limitations with this approach, including
>the way your Loreta is probably implemented.
>
>For examples/applications, please look at:
> Bidaut LM, Pascual-Marqui R, Delavelle J, et al. Three- to
>five-dimensional multisensor imaging for the assessment of neurological
>(dys)function. Journal of Digital Imaging;1996; 9(4):185-198
> Bidaut, L. Model-based multi-constrained integration of invasive
>electrophysiology with other modalities. SPIE-Medical Imaging;2001;
>4319:681-192
>
>Kind regards,
>Luc Bidaut
>
>
>
>-----Original Message-----
>From: mstanoni [mailto:[log in to unmask]]
>Sent: Wednesday, February 13, 2002 9:40 AM
>To: SPM
>Subject: coregistration: loreta EEG and MRI
>
>
>
>
> Dear SPMers:
>
>I wonder if anybody might have any information whether loreta EEG scans
>can be coregister with MRI scans using SPM?
>
>Any pointers to reference materials would also be appreciated.
>
>
>Thank you.
>
>
>M. de Leonni Stanonik
>University of Tennessee Medical Center
>
>
|