title: Bias between MNI and Talairach coordinates analyzed using the ICBM-152 brain template.
abstract: MNI coordinates determined using SPM2 and FSL/FLIRT with the ICBM-152 template were compared to Talairach coordinates determined using a landmark-based Talairach registration method (TAL). Analysis revealed a clear-cut bias in reference frames (origin, orientation) and scaling (brain size). Accordingly, ICBM-152 fitted brains were consistently larger, oriented more nose down, and translated slightly down relative to TAL fitted brains. Whole brain analysis of MNI/Talairach coordinate disparity revealed an ellipsoidal pattern with disparity ranging from zero at a point deep within the left hemisphere to greater than 1-cm for some anterior brain areas. MNI/Talairach coordinate disparity was generally less for brains fitted using FSL. The mni2tal transform generally reduced MNI/Talairach coordinate disparity for inferior brain areas but increased disparity for anterior, posterior, and superior areas. Coordinate disparity patterns differed for brain templates (MNI-305, ICBM-152) using the same fitting method (FSL/FLIRT) and for different fitting methods (SPM2, FSL/FLIRT) using the same template (ICBM-152). An MNI-to-Talairach (MTT) transform to correct for bias between MNI and Talairach coordinates was formulated using a best-fit analysis in one hundred high-resolution 3-D MR brain images. MTT transforms optimized for SPM2 and FSL were shown to reduced group mean MNI/Talairach coordinate disparity from a 5-13 mm to 1-2 mm for both deep and superficial brain sites. MTT transforms provide a validated means to convert MNI coordinates to Talairach compatible coordinates for studies using either SPM2 or FSL/FLIRT with the ICBM-152 template.
authors.affiliation: Research Imaging Center, University of Texas Health Science Center, San Antonio, Texas, USA. jlancaster@uthscsa.edu
authors.forename: Jack L
authors.initials: JL
authors.lastname: Lancaster
authors.forename: Diana
authors.initials: D
authors.lastname: Tordesillas-Gutiérrez
authors.forename: Michael
authors.initials: M
authors.lastname: Martinez
authors.forename: Felipe
authors.initials: F
authors.lastname: Salinas
authors.forename: Alan
authors.initials: A
authors.lastname: Evans
authors.forename: Karl
authors.initials: K
authors.lastname: Zilles
authors.forename: John C
authors.initials: JC
authors.lastname: Mazziotta
authors.forename: Peter T
authors.initials: PT
authors.lastname: Fox
mesh_terms: D000465:Algorithms; D015982:Bias; D001921:Brain / Q000033:anatomy & histology* / Q000473:pathology; D001931:Brain Mapping / Q000379:methods*; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008953:Models, Anatomic; D010363:Pattern Recognition, Automated; D012016:Reference Values; D012984:Software; D013238:Stereotaxic Techniques