Voxel-based morphometry
John Ashburner
Institute of Neurology
At its simplest, voxel-based morphometry (VBM) involves a voxel-wise comparison of the regional amounts of grey matter between two groups of subjects. The procedure is relatively straightforward and involves spatially normalizing high-resolution images from all the subjects in the study into the same stereotactic space. This is followed by segmenting the grey matter from the spatially normalized images, correcting the grey matter segments for volumetric changes incurred during the spatial normalization, and smoothing. Voxel-wise parametric statistical tests are performed to compare the smoothed grey-matter images from the two groups. Corrections for multiple comparisons are made using the theory of Gaussian random fields.
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