Hi all,
I noticed that some automated pipelines from other software packages apply intensity normalization (adjusting the global intensity range). For example, FreeSurfer scales the intensities for all voxels so that the mean intensity of the white matter is 110. BRAINS rescales images so that an intensity of 10 represents pure cerebrospinal fluid, 130 pure gray matter, and 250 indicates pure white matter.
If I am correct, 'new segment' in SPM8 does address intensity-inhomogeneity (intensity non-uniformity) through the options "Bias regularisation" and "Bias FWHM".
However, I am not aware of an option that deals with intensity normalization for structural (T1) data in SPM. I was wondering if it is encouraged to rescale T1 images as part of the pre-processing before segmentation. If so, what would be the best way to accomplish this?
Thanks, Vincent
|