title: Redistribution of inhaled hyperpolarized 3He gas during breath-hold differs by asthma severity.
abstract: The purpose of this work was to quantify the redistribution of ventilation-weighted signal in the lungs of asthmatic subjects during a breath-hold using high temporal-spatial resolution hyperpolarized (HP) He-3 MRI. HP He-3 MRI was used to obtain time-resolved, volumetric images of lung ventilation during breath-hold in 39 human subjects classified as either healthy/nondiseased (n = 14), mild-to-moderate asthmatic (n = 17), or severely asthmatic (n = 8). Signals were normalized to a standard lung volume, so that voxels within the lung from all 39 subjects could be analyzed as a group to increase statistical power and enable semiautomated classification of voxels into 1 of 5 ventilation level categories (ranging from defect to hyperintense). End-inspiratory ventilation distribution and temporal rates of mean signal change for each of the five ventilation categories were compared using ANOVA. Time rates of signal change were hypothesized to represent underlying gas redistribution processes, potentially influenced by disease. We found that mild-to-moderate asthmatic subjects showed the greatest rate of signal change, even though those with severe asthma had the greatest end-inspiration ventilation heterogeneity. The observed results support the existence of local differences in airway resistances associated with the different obstructive patterns in the lungs for severe vs. mild-to-moderate asthmatic subjects.
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Wisconsin;
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hahn
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Wisconsin;
authors.forename: Robert V
authors.initials: RV
authors.lastname: Cadman
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, Wisconsin; Department of Medicine, University of Wisconsin-Madison, Wisconsin; Departments of Pediatrics and Biomedical Engineering; University of Wisconsin-Madison, Wisconsin.
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Sorkness
authors.affiliation: Department of Medicine, University of Wisconsin-Madison, Wisconsin;
authors.forename: Nizar N
authors.initials: NN
authors.lastname: Jarjour
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Wisconsin; Department of Radiology, University of Wisconsin-Madison, Wisconsin; and Departments of Pediatrics and Biomedical Engineering; University of Wisconsin-Madison, Wisconsin.
authors.forename: Scott K
authors.initials: SK
authors.lastname: Nagle
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Wisconsin; Department of Radiology, University of Wisconsin-Madison, Wisconsin; and Departments of Pediatrics and Biomedical Engineering; University of Wisconsin-Madison, Wisconsin sfain@wisc.edu.
authors.forename: Sean B
authors.initials: SB
authors.lastname: Fain
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000378:metabolism* / Q000503:physiopathology*; D062485:Breath Holding; D005260:Female; D006371:Helium / Q000378:metabolism*; D006801:Humans; D008168:Lung / Q000378:metabolism* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012123:Pulmonary Ventilation / Q000502:physiology*; D012119:Respiration; D055815:Young Adult
chemical_list: D006371:Helium
keywords: asthma; functional ventilation; hyperpolarized gas MRI; pendelluft; ventilation dynamics