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<div class="moz-cite-prefix">Hi Jeff,<br>
<br>
Q3:<br>
yes, FEM can model anisotropy and white matter is anisotropic, but
skull is a three-layered-structure <br>
consisting of spongiosa and compacta, see <br>
<a class="moz-txt-link-freetext" href="http://www.ncbi.nlm.nih.gov/pubmed/20690140">http://www.ncbi.nlm.nih.gov/pubmed/20690140</a><br>
<br>
For Q4:<br>
FEM allows geometry-adaptation, see <br>
<a class="moz-txt-link-freetext" href="http://www.ncbi.nlm.nih.gov/pubmed/17694865">http://www.ncbi.nlm.nih.gov/pubmed/17694865</a><br>
As far as I know, modeling using irregular meshes might get
difficult to implement within an FDM framework. <br>
<br>
For Q1 and Q2:<br>
Mainly tissues between sources and electrodes are important to be
modeled (so white matter anisotropy<br>
is only important for deeper sources) and FSL and freesurfer can
do a good job on segmentation. <br>
Air-compartments can possibly best be modeled by hand-correction
of the FSL output.<br>
Please see <br>
<a class="moz-txt-link-freetext" href="http://www.ncbi.nlm.nih.gov/pubmed/24671208">http://www.ncbi.nlm.nih.gov/pubmed/24671208</a><br>
on how we solve forward modeling to be able to combine EEG and
MEG.<br>
<br>
More infos are available in the two following theses:<br>
<a class="moz-txt-link-freetext"
href="http://www.sci.utah.edu/%7Ewolters/PaperWolters/2014/Lanfer_Dissertation_July2-2014.pdf">http://www.sci.utah.edu/~wolters/PaperWolters/2014/Lanfer_Dissertation_July2-2014.pdf</a><br>
<a class="moz-txt-link-freetext"
href="http://www.sci.utah.edu/%7Ewolters/PaperWolters/2015/Umit_Aydin_Dissertation_2015.pdf">http://www.sci.utah.edu/~wolters/PaperWolters/2015/Umit_Aydin_Dissertation_2015.pdf</a><br>
<br>
<br>
Best regards<br>
Carsten<br>
<br>
Am 02.12.2015 um 03:04 schrieb K Jeffrey Eriksen:<br>
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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am reading the FieldTrip documentation on
creating an FEM model and see that the following tissue types
are output from the segmentation process:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Gray<o:p></o:p></p>
<p class="MsoNormal">White<o:p></o:p></p>
<p class="MsoNormal">Csf<o:p></o:p></p>
<p class="MsoNormal">Skull<o:p></o:p></p>
<p class="MsoNormal">Scalp<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Q1: Since I am using a 256 channel EGI
system with electrodes over the lower part of the head and
face, I absolutely need to be able to include air voxels as
well. Anyone have any knowledge of such a possibility?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Q2: Beyond that I would also like to
include other tissue types such as fat, muscle, and eyeball
(vitrious). I suppose I could find other segmentation software
to simply create a more varied segmentation and insert it in
the processing pipeline, but would like to know if that would
mess anything up.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Q3: Next, can the FEM handle anisotropic
conductivities for white matter and skull?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Q4: has anyone out there actually used the
FDM model? <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">-Jeff Eriksen<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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