I am having issue with calculate the volume of the source..
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After volume model (MRI volume - in 2mm) => I ran source in the dSPM model. I would like to see the difference and compare the volume on EEG and MEG simultaneous recording.
Then I display the source on 3D T1. Then I create the new vertex (new scout) then using the constrained under the scout size (the issue being the scout didn't follow the source and didn't fill up the whole source. In addition, the vertices stopped moving when it touch one side of the source, and it couldn't be dilated. Give the source didn't follow the circular shape not sure in which way I can calculate.
I tried the surface model and in surface model the constrained with scout work really wall. but in the volume model it doesn't. I am trying to avoid doing mixed model (not sure it is right way to do it) and thus I am stuck.
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Please see the image... Any advice or suggestion == thank you in advance.
If anyone has better advice in how I can measure the volume in this situation... => please help....
I made few tests over here, and the Constrained option to grow Scouts seems to work fine with Surface and Volume Scouts.
The behaviour that you are experiencing may be caused by the fact that the volume sources are not defined in the MRI voxel space, but in the source grid that is defined when computing the head model.
To visualize the sources on the MRI slices, there is an interpolation from the sources grid to the MRI voxel space, and the thresholding (Amplitude slicer on the Surface tab) is applied on those interpolated values on the MRI.
However volume Scouts are not defined in the MRI voxels, but on the sources grid. So, when the Constrained option is used, it adds a new source grid point to the scout if the source value for an adjacent grid point is higher than the threshold, regardless of the interpolated value on the MRI.
To see this effect clearer, change the Overlay options to * Smooth: None, and uncheck the Interpolation sources>MRI > Interpolate values option.
