Voxel-based morphometry

<p>Voxel-based morphometry is a computational approach to <a href="/facts/Neuroanatomy/VJxVXoWm">neuroanatomy</a> that measures differences in local concentrations of brain tissue, through a voxel-wise comparison of multiple brain images.
In traditional <a href="/facts/Morphometry/sXgTqQCX">morphometry</a>, volume of the whole brain or <a href="/facts/List_of_regions_in_the_human_brain/N8r44v6P">its subparts</a> is measured by drawing regions of interest (ROIs) on images from <a href="/facts/Brain_scanning/dA5Cteaf">brain scanning</a> and calculating the <a href="/facts/Volume/aeAXCBUd">volume</a> enclosed. However, this is time consuming and can only provide measures of rather large areas. Smaller differences in volume may be overlooked. The value of VBM is that it allows for comprehensive measurement of differences, not just in specific structures, but throughout the entire brain. VBM <a href="/facts/Image_registration/y2KUwdRL">registers</a> every brain to a template, which gets rid of most of the large differences in brain anatomy among people. Then the brain images are smoothed so that each <a href="/facts/Voxel/xo077lPE">voxel</a> represents the average of itself and its neighbors. Finally, the image volume is compared across brains at every voxel.
</p><p>However, VBM can be sensitive to various artifacts, which include misalignment of brain structures, misclassification of tissue types, differences in folding patterns and in cortical thickness. All these may confound the statistical analysis and either decrease the sensitivity to true volumetric effects, or increase the chance of false positives. For the cerebral cortex, it has been shown that volume differences identified with VBM may reflect mostly differences in surface area of the cortex, rather than differences in cortical thickness.
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Voxel-based morphometry open-in-new

Voxel-based morphometry