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Detection of smoothly distributed spatial outliers, with applications to identifying the distribution of parenchymal hyperinflation following an airway challenge in asthmatics
Journal article   Open access   Peer reviewed

Detection of smoothly distributed spatial outliers, with applications to identifying the distribution of parenchymal hyperinflation following an airway challenge in asthmatics

Andrew L Thurman, Jiwoong Choi, Sanghun Choi, Ching-Long Lin, Eric A Hoffman, Chang Hyun Lee and Kung-Sik Chan
Statistics in medicine, Vol.36(10), pp.1638-1654
05/10/2017
DOI: 10.1002/sim.7216
PMCID: PMC5842699
PMID: 28132419
url
http://doi.org/10.1002/sim.7216View
Open Access

Abstract

Methacholine challenge tests are used to measure changes in pulmonary function that indicate symptoms of asthma. In addition to pulmonary function tests, which measure global changes in pulmonary function, computed tomography images taken at full inspiration before and after administration of methacholine provide local air volume changes (hyper-inflation post methacholine) at individual acinar units, indicating local airway hyperresponsiveness. Some of the acini may have extreme air volume changes relative to the global average, indicating hyperresponsiveness, and those extreme values may occur in clusters. We propose a Gaussian mixture model with a spatial smoothness penalty to improve prediction of hyperresponsive locations that occur in spatial clusters. A simulation study provides evidence that the spatial smoothness penalty improves prediction under different data-generating mechanisms. We apply this method to computed tomography data from Seoul National University Hospital on five healthy and ten asthmatic subjects. Copyright © 2017 John Wiley & Sons, Ltd.
Biostatistics Asthma - physiopathology Respiratory Function Tests - statistics & numerical data Humans Middle Aged Male Asthma - diagnostic imaging Models, Statistical Case-Control Studies Normal Distribution Bronchial Hyperreactivity Likelihood Functions Tomography, X-Ray Computed - statistics & numerical data Bronchial Provocation Tests - statistics & numerical data Computer Simulation Adult Female Methacholine Chloride

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