On- and offline talairach registration for structural and functional MRI studies

We present a method for registering a brain in the Talairach coordinate system that can be performed either 'online,' i.e., in real time while a subject is in a magnetic resonance scanner, or 'offline' on a previously acquired three-dimensional (3D) data set. The method is applicable to functional magnetic resonance imaging (MRI) studies because slices can be specified in Talairach coordinates and acquired in Talairach planes. Once functional data are obtained, pixels in a functional map can then be converted into Talairach coordinates, thereby facilitating brain averaging and communication of results. The method can also be used to align 3D data sets and perform volumetric analyses of regions of interest after correcting for head tilt, or to compute averaged structural brain images. Online and offline registration can be combined such that a series of sections can be interactively selected and visualized ahead of time using offline analyses and then replicated online at a later time.