• Damien Pike, Miranda Kirby, Fumin Guo, David G McCormack, and Grace Parraga.
• Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond St N, London, ON, Canada N6A 5B7; Department of Medical Biophysics, The University of Western Ontario, London, Canada.
• Acad Radiol. 2015 Aug 1; 22 (8): 1068-78.

Rationale And ObjectivesHyperpolarized (3)He magnetic resonance imaging (MRI) ventilation abnormalities are visible in ex-smokers without airflow limitation, but the clinical relevance of this is not well-understood. Our objective was to phenotype healthy ex-smokers with normal and abnormally elevated ventilation defect percent (VDP).Materials And MethodsSixty ex-smokers without airflow limitation provided written informed consent to (3)He MRI, computed tomography (CT), and pulmonary function tests in a single visit. (3)He MRI VDP and apparent diffusion coefficients (ADCs) were measured for whole-lung and each lung lobe as were CT measurements of emphysema (relative area [RA] with attenuation ≤-950 HU, RA950) and airway morphology (wall area percent [WA%], lumen area [LA] and LA normalized to body surface area [LA/BSA]).ResultsIn 42 ex-smokers, there was abnormally elevated VDP and no significant differences for pulmonary function, RA950, or airway measurements compared to 18 ex-smokers with normal VDP. Ex-smokers with abnormally elevated VDP reported significantly greater (3)He ADC in the apical lung (right upper lobe [RUL], P = .02; right middle lobe [RML], P = .04; and left upper lobe [LUL], P = .009). Whole lung (r = 0.40, P = .001) and lobar VDP (RUL, r = 0.32, P = .01; RML, r = 0.46, P = .002; right lower lobe [RLL], r = 0.38, P = .003; LUL, r = 0.35, P = .006; and left lower lobe, r = 0.37, P = .004) correlated with regional (3)He ADC. Although whole-lung VDP and CT airway morphology measurements were not correlated, regional VDP was correlated with RUL LA (r = -0.37, P = .004), LA/BSA (r = -0.42, P = .0008), RLL WA% (r = 0.28, P = .03), LA (r = -0.28, P = .03), and LA/BSA (r = -0.37, P = .004).ConclusionsAbnormally elevated VDP in ex-smokers without airflow limitation was coincident with very mild emphysema detected using MRI and regional airway remodeling detected using CT representing a subclinical obstructive lung disease phenotype.Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

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