Computational Anatomy: VBM and Alternatives. Overview. Volumetric differences Serial Scans Jacobian Determinants Voxel-based Morphometry Multivariate Approaches Difference Measures Another approach. Deformation Field. Original. Warped. Template. Deformation field. Jacobians.
Jacobian Matrix (or just “Jacobian”)
Jacobian Determinant (or just “Jacobian”) - relative volumes
Data from the Dementia Research Group, Queen Square.
CSF “modulated” by relative volumes
Late CSF - Early CSF
Smoothing is done by convolution.
Each voxel after smoothing effectively becomes the result of applying a weighted region of interest (ROI).
Convolved with a circle
Convolved with a Gaussian
Warped, Modulated Grey Matter
12mm FWHM Smoothed Version
Where should any difference between the two “brains” on the left and that on the right appear?
w is a weighted linear combination of the support vectors
Slide from Tilak Ratnanather
Pictures taken from http://www.messybeast.com/freak-face.htm
surface is larger
in dominant hemisphere