title: A four-dimensional computed tomography comparison of healthy and asthmatic human lungs.
abstract: The purpose of this study was to explore new insights in non-linearity, hysteresis and ventilation heterogeneity of asthmatic human lungs using four-dimensional computed tomography (4D-CT) image data acquired during tidal breathing. Volumetric image data were acquired for 5 non-severe and one severe asthmatic volunteers. Besides 4D-CT image data, function residual capacity and total lung capacity image data during breath-hold were acquired for comparison with dynamic scans. Quantitative results were compared with the previously reported analysis of five healthy human lungs. Using an image registration technique, local variables such as regional ventilation and anisotropic deformation index (ADI) were estimated. Regional ventilation characteristics of non-severe asthmatic subjects were similar to those of healthy subjects, but different from the severe asthmatic subject. Lobar airflow fractions were also well correlated between static and dynamic scans (R2>0.84). However, local ventilation heterogeneity significantly increased during tidal breathing in both healthy and asthmatic subjects relative to that of breath-hold perhaps because of airway resistance present only in dynamic breathing. ADI was used to quantify non-linearity and hysteresis of lung motion during tidal breathing. Non-linearity was greater on inhalation than exhalation among all subjects. However, exhalation non-linearity among asthmatic subjects was greater than healthy subjects and the difference diminished during inhalation. An increase of non-linearity during exhalation in asthmatic subjects accounted for lower hysteresis relative to that of healthy ones. Thus, assessment of non-linearity differences between healthy and asthmatic lungs during exhalation may provide quantitative metrics for subject identification and outcome assessment of new interventions.
authors.affiliation: Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA, USA; IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, IA, USA; Department of Radiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
authors.forename: Nariman
authors.initials: N
authors.lastname: Jahani
authors.affiliation: Department of Mechanical Engineering, Kyungpook National University, Daegu, South Korea.
authors.forename: Sanghun
authors.initials: S
authors.lastname: Choi
authors.affiliation: Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA, USA; IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, IA, USA.
authors.forename: Jiwoong
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA, USA; IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, IA, USA.
authors.forename: Babak
authors.initials: B
authors.lastname: Haghighi
authors.affiliation: Department of Biomedical Engineering, The University of Iowa, Iowa City, IA, USA; Department of Internal Medicine, The University of Iowa, Iowa City, IA, USA; Department of Radiology, The University of Iowa, Iowa City, IA, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Hoffman
authors.affiliation: Department of Internal Medicine, The University of Iowa, Iowa City, IA, USA.
authors.forename: Alejandro P
authors.initials: AP
authors.lastname: Comellas
authors.affiliation: Department of Internal Medicine, The University of Iowa, Iowa City, IA, USA.
authors.forename: Joel N
authors.initials: JN
authors.lastname: Kline
authors.affiliation: Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA, USA; IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, IA, USA. Electronic address: ching-long-lin@uiowa.edu.
authors.forename: Ching-Long
authors.initials: CL
authors.lastname: Lin
mesh_terms: D000328:Adult; D001249:Asthma / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000502:physiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012119:Respiration
keywords: Asthma; Four-dimensional computed tomography; Hysteresis; Image registration; Ventilation heterogeneity