Comparison of spatial normalization procedures and their impact on functional maps
Hum. Brain Mapp.. 2002-01-01; 16(4): 228-250
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1. Hum Brain Mapp. 2002 Aug;16(4):228-50.
Comparison of spatial normalization procedures and their impact on functional
Crivello F(1), Schormann T, Tzourio-Mazoyer N, Roland PE, Zilles K, Mazoyer BM.
(1)Groupe d’Imagerie Neurofonctionnelle, UMR 6095, CNRS-CEA LRC36V Université de
Caen & Paris 5, Caen, France.
The alignment accuracy and impact on functional maps of four spatial
normalization procedures have been compared using a set of high resolution brain
MRIs and functional PET volumes acquired in 20 subjects. Simple affine (AFF),
fifth order polynomial warp (WRP), discrete cosine basis functions (SPM), and a
movement model based on full multi grid (FMG) approaches were applied on the same
dataset for warping individual volumes onto the Human Brain Atlas (HBA) template.
Intersubject averaged structural volumes and tissue probability maps were
compared across normalization methods and to the standard brain. Thanks to the
large number of degrees of freedom of the technique, FMG was found to provide
enhanced alignment accuracy as compared to the other three methods, both for the
grey and white matter tissues; WRP and SPM exhibited very similar performances
whereas AFF had the lowest registration accuracy. SPM, however, was found to
perform better than the other methods for the intra-cerebral cerebrospinal fluid
(mainly in the ventricular compartments). Limited differences in terms of
activation morphology and detection sensitivity were found between low resolution
functional maps (FWHM approximately 10 mm) spatially normalized with the four
methods, which overlapped in 42.8% of the total activation volume. These findings
suggest that the functional variability is much larger than the anatomical one
and that precise alignment of anatomical features has low influence on the
resulting intersubject functional maps. When increasing the spatial resolution to
approximately 6 mm, however, differences in localization of activated areas
appear as a consequence of the different spatial normalization procedure used,
restricting the overlap of the normalized activated volumes to only 6.2%.
Copyright 2002 Wiley-Liss, Inc.
PMID: 12112765 [Indexed for MEDLINE]