Parametric response mapping of COPD phenotypes: A COPDGene study

Background: Chronic obstructive pulmonary disease (COPD) has few effective treatments due to its various phenotypes. Analytical techniques for quantitative CT may provide more accurate diagnoses. Methods: We Evaluated parametric response mapping (PRM) from a subset (n=4832: GOLD 0-4) of over 7,281 smokers with and without COPD accrued for the COPDGene study. PRM classifies lung by thresholding HU values from spatially aligned inspiration/expiration (Ins/Exp) HRCT. PRM fSAD and PRM Emph , which represent functional small airways disease and emphysema, respectively, were correlated to FEV1pp, 6-min walking distance, St. George Respiratory Questionnaire, BODE and history of severe exacerbation in the prior year. Statistical analysis was performed using linear or logistic modeling controlling for age, BMI, pack years and gender. Results: PRM measures for emphysema and small airways disease were both independently associated with SGRQ, BODE and severe exacerbations. Conclusions: PRM, an imaging biomarker, provides an opportunity to understand the impact of structural abnormality on clinical disease severity in COPD.