Lumen area change (Delta Lumen) between inspiratory and expiratory CT as a measure of severe outcomes in asthma

Publication date: Available online 10 February 2018
Source:Journal of Allergy and Clinical Immunology
Author(s): Sung Shine Shim, Mark L. Schiebler, Michael D. Evans, Nizar Jarjour, Ron L. Sorkness, Loren Denlinger, Alfonso Rodriguez, Sally Wenzel, Eric A. Hoffman, Ching-Long Lin, David S. Gierada, Mario Castro, Sean B. Fain
BackgroundQuantitative computed tomography (QCT) biomarkers of airway morphology hold potential for understanding and monitoring regional airway remodeling in asthma.ObjectiveWe sought to determine if the change of airway lumen area between TLC and FRC lung volumes measured from CT imaging data was correlated with severe outcomes in asthma patients.MethodsWe studied 152 asthma patients (90 female and 62 male) and 33 normal subjects (12 female and 21 male) with QCT. Post-processing of airways at generations 1-5 (1 = trachea) was performed for wall area percent (WA%), wall thickness percent (WT%), lumen area at baseline TLC (LATLC) and FRC (LAFRC) and low attenuation area at FRC. A new metric (reflecting remodeling and/or distal air trapping), Delta Lumen, was determined from the percent normalized difference in lumen area defined as (LATLC - LAFRC ) / LATLC x 100.ResultsPost-processing of 4501 airway segments was performed (3681 segments in the 152 subjects with asthma and 820 segments in the 33 normal subjects, range 17-28 segments per subject). Delta Lumen was negatively correlated with WT% and low attenuation area (p<0.01) in asthma subjects. Delta Lumen was significantly lower for airway generations 3-5 (segmental airways) in subjects undergoing hospitalization due to exacerbation and in refractory asthma requiring treatment with systemic corticosteroids. WT% and low attenuation area were positively, and Delta Lumen was negatively, associated with systemic corticosteroid treatment (p<0.05) suggesting reduced Delta Lumen is a potential outcomes biomarker in severe asthma.ConclusionReduced Delta Lumen of the central airways measured on QCT is a promising exploratory biomarker of unstable refractory asthma that warrants further study.



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