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In nonstationary images, cluster inference depends on the local image smoothness, as clusters tend to be larger in smoother regions by chance alone. In order to correct the inference for such nonstationary, cluster sizes can be adjusted according to a local smoothness estimate. In this study, adjusted cluster sizes are used in a permutation-testing framework for both cluster-based and threshold-free cluster enhancement (TFCE) inference and tested on both simulated and real data. We find that TFCE inference is already fairly robust to nonstationarity in the data, while cluster-based inference requires an adjustment to ensure homogeneity. A group of possible multi-level adjustments are introduced and their results on simulated and real data are assessed using a new performance index. We also find that adjusting for local smoothness via a separate resampling procedure is more effective at removing nonstationarity than an adjustment via a random field theory based smoothness estimator.

Original publication

DOI

10.1016/j.neuroimage.2010.09.088

Type

Journal article

Journal

NeuroImage

Publication Date

02/2011

Volume

54

Pages

2006 - 2019

Addresses

Centre for Functional MRI of the Brain (FMRIB), University of Oxford, Oxford, UK. reza@fmrib.ox.ac.uk

Keywords

Brain, Humans, Alzheimer Disease, False Positive Reactions, Magnetic Resonance Imaging, Brain Mapping, Cluster Analysis, Data Interpretation, Statistical, Linear Models, Normal Distribution, Reproducibility of Results, ROC Curve, Cognition Disorders, Algorithms, Computer Simulation, Image Processing, Computer-Assisted