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dc.contributor.authorPardoe, Heath Ren
dc.contributor.authorAbbott, David Fen
dc.contributor.authorJackson, Graeme Den
dc.identifier.citationHuman Brain Mapping 2012; 34(11): 3000-9en
dc.description.abstractCortical thickness mapping is a widely used method for the analysis of neuroanatomical differences between subject groups. We applied power analysis methods over a range of image processing parameters to derive a model that allows researchers to calculate the number of subjects required to ensure a well-powered cross-sectional cortical thickness study.0.9-mm isotropic T1 -weighted 3D MPRAGE MRI scans from 98 controls (53 females, age 29.1 ± 9.7 years) were processed using Freesurfer 5.0. Power analyses were carried out using vertex-wise variance estimates from the coregistered cortical thickness maps, systematically varying processing parameters. A genetic programming approach was used to derive a model describing the relationship between sample size and processing parameters. The model was validated on four Alzheimer's Disease Neuroimaging Initiative control datasets (mean 126.5 subjects/site, age 76.6 ± 5.0 years).Approximately 50 subjects per group are required to detect a 0.25-mm thickness difference; less than 10 subjects per group are required for differences of 1 mm (two-sided test, 10 mm smoothing, α = 0.05). Sample size estimates were heterogeneous over the cortical surface. The model yielded sample size predictions within 2-6% of that determined experimentally using independent data from four other datasets. Fitting parameters of the model to data from each site reduced the estimation error to less than 2%.The derived model provides a simple tool for researchers to calculate how many subjects should be included in a well-powered cortical thickness analysis.en
dc.subject.othercortical thicknessen
dc.subject.otherpower analysisen
dc.subject.otherstudy designen
dc.subject.otherAnatomy, Cross-Sectional.methodsen
dc.subject.otherBrain Mapping.methodsen
dc.subject.otherCerebral Cortex.anatomy & histologyen
dc.subject.otherCohort Studiesen
dc.subject.otherData Interpretation, Statisticalen
dc.subject.otherGenetic Processesen
dc.subject.otherImage Processing, Computer-Assisteden
dc.subject.otherMagnetic Resonance Imagingen
dc.subject.otherModels, Neurologicalen
dc.subject.otherReproducibility of Resultsen
dc.subject.otherSample Sizeen
dc.subject.otherYoung Adulten
dc.titleSample size estimates for well-powered cross-sectional cortical thickness studies.en
dc.typeJournal Articleen
dc.identifier.journaltitleHuman brain mappingen
dc.identifier.affiliationBrain Research Institute, Florey Neuroscience Institutes, Melbourne Brain Centre, Austin Hospital, Heidelberg, Victoria, Australiaen
dc.identifier.affiliationDepartment of Medicine, The University of Melbourne, Victoria, Australiaen
dc.contributor.corpauthorAlzheimer's Disease Neuroimaging Initiativeen
dc.type.austinJournal Articleen
item.fulltextNo Fulltext-
item.openairetypeJournal Article- Florey Institute of Neuroscience and Mental Health- Florey Institute of Neuroscience and Mental Health-
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