title: Detection of smoothly distributed spatial outliers, with applications to identifying the distribution of parenchymal hyperinflation following an airway challenge in asthmatics.
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.
authors.affiliation: Department of Statistics and Actuarial Science, College of Liberal Arts and Sciences, The University of Iowa, Iowa City, 52242, IA, U.S.A.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Thurman
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, The University of Iowa, Iowa City, 52242, IA, U.S.A.
authors.forename: Jiwoong
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, The University of Iowa, Iowa City, 52242, IA, U.S.A.
authors.forename: Sanghun
authors.initials: S
authors.lastname: Choi
authors.affiliation: Department of Mechanical and Industrial Engineering, College of Engineering, The University of Iowa, Iowa City, 52242, IA, U.S.A.
authors.forename: Ching-Long
authors.initials: CL
authors.lastname: Lin
authors.affiliation: Department of Radiology, Carver College of Medicine, The University of Iowa, Iowa City, 52242, IA, U.S.A.|Department of Biomedical Engineering, College of Engineering, The University of Iowa, Iowa City, 52242, IA, U.S.A.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Hoffman
authors.affiliation: Department of Radiology, Seoul National University Hospital, 28 Yeongeon-dong, Jongno-gu, Seoul, 110-744, Korea.
authors.forename: Chang Hyun
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Department of Statistics and Actuarial Science, College of Liberal Arts and Sciences, The University of Iowa, Iowa City, 52242, IA, U.S.A.
authors.forename: Kung-Sik
authors.initials: KS
authors.lastname: Chan
mesh_terms: D000328:Adult; D001249:Asthma / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D056808:Biostatistics; D016535:Bronchial Hyperreactivity; D001985:Bronchial Provocation Tests / Q000706:statistics & numerical data; D016022:Case-Control Studies; D003198:Computer Simulation; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D015233:Models, Statistical; D016011:Normal Distribution; D012129:Respiratory Function Tests / Q000706:statistics & numerical data*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data
chemical_list: D016210:Methacholine Chloride
keywords: asthma; generalized additive model; methacholine challenge; mixture; panel of random fields