Hi all,

 

I started developing this concern when comparing Segmentation results (white matter, grey matter and CSF) between SPM and FSL; When looking at for instance Grey matter, as far as the histogram is concern, I was expecting to see a Gaussian distribution, is this not a correct assumption?

I could see bell shape histogram for FSL segmented data, but I was expecting to see the peak where probability is equal to 1 but the peak was at p=0.5

 

For SPM segmented data, I see a flat histogram with minor peaks at p=1 and p=0, not sure why?

 

I am entirely puzzled by this, based on my understanding of Gaussian Mixture Models and Expectation maximization algorithm, you separate three Gaussians (ideally speaking, eliminating bias field corruption), then you build your probability mask based on the mean and standard deviation of the calculated Gaussians,  so histogram of the Segmented data should somehow reflect this Gaussian nature, right ?

 

Your thoughts on this are highly appreciated

 

-P