Registration - based Assessment of Regional Lung Function via Volumetric CT Images of 1 Normals vs . Severe Asthmatics

22 The purpose of this work is to explore the use of image registration-derived variables associated 23 with computed tomographic (CT) imaging of the lung acquired at multiple volumes. As an 24 evaluation of the utility of such an imaging approach, we explore two groups at the extremes of 25 population ranging from normals to severe asthmatics. A mass preserving image registration 26 technique is employed to match CT images at total lung capacity (TLC) and functional residual 27 capacity (FRC) for assessment of regional air volume change and lung deformation between the 28 two states. Fourteen normals and thirty severe asthmatics were analyzed via image registration29 derived metrics together with their pulmonary function test (PFT) and CT-based air-trapping. 30 Relative to the normals, the severe asthmatic group demonstrates reduced air volume change 31 (consistent with air trapping) and more isotropic deformation in the basal lung regions, while 32 demonstrating increased air volume change associated with increased anisotropic deformation in 33 the apical lung regions. These differences are found despite the fact that both PFT-derived TLC 34 and FRC in the two groups are near 100% of predicted values. Data suggest that reduced basal35 lung air volume change in severe asthmatics is compensated by increased apical-lung air volume 36 change and that relative increase in apical-lung air volume change in severe asthmatics is 37 accompanied by enhanced anisotropic deformation. These data suggest that CT-based 38 deformation, assessed via inspiration vs. expiration scans, provides a tool for distinguishing 39 differences in lung mechanics when applied to the extreme ends of a population range. 40 Keyword: Lung Mechanics, Quantitative Computed Tomography, Image Registration, Air 41 Trapping, Asthma 42 by 10.0.33.4 on A ril 6, 2017 http://jaysiology.org/ D ow nladed fom