Hi, This is a 12-dof registration, using both brain and skull images, with the skull images used to determine the scaling component of that. Cheers. On 7 Jul 2010, at 15:56, Anna Barnes wrote: > When SIENA does the co-registration between image 1 and image 2 based on the skull does it just use a 6 parameter rigid body or a 7 parameter transform. > > thanks > Anna > --------------------------------------------------------------------------- Stephen M. Smith, Professor of Biomedical Engineering Associate Director, Oxford University FMRIB Centre FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK +44 (0) 1865 222726 (fax 222717) [log in to unmask] http://www.fmrib.ox.ac.uk/~steve ---------------------------------------------------------------------------