title: Optimizing full-brain coverage in human brain MRI through population distributions of brain size.
abstract: When defining an MRI protocol, brain researchers need to set multiple interdependent parameters that define repetition time (TR), voxel size, field-of-view (FOV), etc. Typically, researchers aim to image the full brain, making the expected FOV an important parameter to consider. Especially in 2D-EPI sequences, non-wasteful FOV settings are important to achieve the best temporal and spatial resolution. In practice, however, imperfect FOV size estimation often results in partial brain coverage for a significant number of participants per study, or, alternatively, an unnecessarily large voxel-size or number of slices to guarantee full brain coverage. To provide normative FOV guidelines we estimated population distributions of brain size in the x-, y-, and z-direction using data from 14,781 individuals. Our results indicated that 11mm in the z-direction differentiate between obtaining full brain coverage for 90% vs. 99.9% of participants. Importantly, we observed that rotating the FOV to optimally cover the brain, and thus minimize the number of slices needed, effectively reduces the required inferior-superior FOV size by ~5%. For a typical adult imaging study, 99.9% of the population can be imaged with full brain coverage when using an inferior-superior FOV of 142mm, assuming optimal slice orientation and minimal within-scan head motion. By providing population distributions for brain size in the x-, y-, and z-direction we improve the potential for obtaining full brain coverage, especially in 2D-EPI sequences used in most functional and diffusion MRI studies. We further enable optimization of related imaging parameters including the number of slices, TR and total acquisition time.
authors.affiliation: Department of Cognitive Neuroscience, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands. Electronic address: maarten.mennes@donders.ru.nl.
authors.forename: Maarten
authors.initials: M
authors.lastname: Mennes
authors.affiliation: Centre for Functional MRI of the Brain, University of Oxford, Oxford, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Jenkinson
authors.affiliation: Inserm, U975, CNRS, UMR 7225, CENIR: Centre de NeuroImagerie de Recherche, ICM Paris, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Valabregue
authors.affiliation: Department of Cognitive Neuroscience, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
authors.forename: Jan K
authors.initials: JK
authors.lastname: Buitelaar
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands; Centre for Functional MRI of the Brain, University of Oxford, Oxford, United Kingdom.
authors.forename: Christian
authors.initials: C
authors.lastname: Beckmann
authors.affiliation: Centre for Functional MRI of the Brain, University of Oxford, Oxford, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000033:anatomy & histology*; D002648:Child; D002675:Child, Preschool; D003710:Demography; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging / Q000379:methods*; D055815:Young Adult
keywords: FOV; Field-of-view; Neuroimaging; Population brain size