title: The Impact of Sources of Variability on Parametric Response Mapping of Lung CT Scans.
abstract: Parametric response mapping (PRM) of inspiration and expiration computed tomography (CT) images improves the radiological phenotyping of chronic obstructive pulmonary disease (COPD). PRM classifies individual voxels of lung parenchyma as normal, emphysematous, or nonemphysematous air trapping. In this study, bias and noise characteristics of the PRM methodology to CT and clinical procedures were evaluated to determine best practices for this quantitative technique. Twenty patients of varying COPD status with paired volumetric inspiration and expiration CT scans of the lungs were identified from the baseline COPD-Gene cohort. The impact of CT scanner manufacturer and reconstruction kernels were evaluated as potential sources of variability in PRM measurements along with simulations to quantify the impact of inspiration/expiration lung volume levels, misregistration, and image spacing on PRM measurements. Negligible variation in PRM metrics was observed when CT scanner type and reconstruction were consistent and inspiration/expiration lung volume levels were near target volumes. CT scanner Hounsfield unit drift occurred but remained difficult to ameliorate. Increasing levels of image misregistration and CT slice spacing were found to have a minor effect on PRM measurements. PRM-derived values were found to be most sensitive to lung volume levels and mismatched reconstruction kernels. As with other quantitative imaging techniques, reliable PRM measurements are attainable when consistent clinical and CT protocols are implemented.
authors.affiliation: Department of Radiology, University of Michigan, Center for Molecular Imaging, Ann Arbor, MI.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Boes
authors.affiliation: Department of Radiology, University of Michigan, Center for Molecular Imaging, Ann Arbor, MI.
authors.forename: Maria
authors.initials: M
authors.lastname: Bule
authors.affiliation: Department of Radiology, University of Michigan, Center for Molecular Imaging, Ann Arbor, MI.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Hoff
authors.affiliation: Imbio LLC, Minneapolis, MN.
authors.forename: Ryan
authors.initials: R
authors.lastname: Chamberlain
authors.affiliation: National Jewish Health, Denver, CO.
authors.forename: David A
authors.initials: DA
authors.lastname: Lynch
authors.affiliation: Department of Radiology, University of Michigan, Center for Molecular Imaging, Ann Arbor, MI.
authors.forename: Jadranka
authors.initials: J
authors.lastname: Stojanovska
authors.affiliation: Weill Cornell Medical College, New York, NY.
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Martinez
authors.affiliation: Department of Internal Medicine, University of Michigan, Center for Molecular Imaging, Ann Arbor, MI.
authors.forename: Meilan K
authors.initials: MK
authors.lastname: Han
authors.affiliation: Department of Radiology, University of Michigan, Center for Molecular Imaging, Ann Arbor, MI.
authors.forename: Ella A
authors.initials: EA
authors.lastname: Kazerooni
authors.affiliation: Department of Radiology, University of Michigan, Center for Molecular Imaging, Ann Arbor, MI.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Ross
authors.affiliation: Department of Radiology, University of Michigan, Center for Molecular Imaging, Ann Arbor, MI.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Galbán
keywords: lung disease; parametric response map; quantitative CT; sources of error