Parametric response mapping on chest computed tomography associates with clinical and functional parameters in chronic obstructive pulmonary disease.
BACKGROUND
In the search for specific phenotypes of chronic obstructive pulmonary disease (COPD) computed tomography (CT) derived Parametric Response Mapping (PRM) has been introduced. This study evaluates the association between PRM and currently available biomarkers of disease severity in COPD.


METHODS
Smokers with and without COPD were characterized based on questionnaires, pulmonary function tests, body plethysmography, and low-dose chest CT scanning. PRM was used to calculate the amount of emphysema (PRMEmph) and non-emphysematous air trapping (i.e. functional small airway disease, PRMfSAD). PRM was first compared with other biomarkers for emphysema (Perc15) and air trapping (E/I-ratioMLD). Consequently, linear regression models were utilized to study associations of PRM measurements with clinical parameters.


RESULTS
166 participants were included with a mean ± SD age of 50.5 ± 17.7 years. Both PRMEmph and PRMfSAD were more strongly correlated with lung function parameters as compared to Perc15 and E/I-ratioMLD. PRMEmph and PRMfSAD were higher in COPD participants than non-COPD participants (14.0% vs. 1.1%, and 31.6% vs. 8.2%, respectively, both p < 0.001) and increased with increasing GOLD stage (all p < 0.001). Multivariate analysis showed that PRMfSAD was mainly associated with total lung capacity (TLC) (β = -7.90, p < 0.001), alveolar volume (VA) (β = 7.79, p < 0.001), and residual volume (β = 6.78, p < 0.001), whilst PRMEmph was primarily associated with Kco (β = 8.95, p < 0.001), VA (β = -6.21, p < 0.001), and TLC (β = 6.20, p < 0.001).


CONCLUSIONS
PRM strongly associates with the presence and severity of COPD. PRM therefore appears to be a valuable tool in differentiating COPD phenotypes.
['Pompe|Esther|E|', 'Galbán|Craig J|CJ|', 'Ross|Brian D|BD|', 'Koenderman|Leo|L|', 'Ten Hacken|Nick Ht|NH|', 'Postma|Dirkje S|DS|', 'van den Berge|Maarten|M|', 'de Jong|Pim A|PA|', 'Lammers|Jan-Willem J|JJ|', 'Mohamed Hoesein|Firdaus Aa|FA|']
D000293:Adolescent D000328:Adult D000368:Aged D005260:Female D005541:Forced Expiratory Volume D006801:Humans D007090:Image Interpretation, Computer-Assisted D008297:Male D008875:Middle Aged D010641:Phenotype D029424:Pulmonary Disease, Chronic Obstructive D011656:Pulmonary Emphysema D012129:Respiratory Function Tests D012189:Retrospective Studies D012720:Severity of Illness Index D012907:Smoking D014057:Tomography, X-Ray Computed D014797:Vital Capacity D055815:Young Adult
Parametric response mapping Computed tomography Phenotypes Copd Emphysema Small airway disease