Summary of the main imaging techniques available at bedside for assessment of chronic obstructive pulmonary disease

TargetPrincipleMain features
Emphysema extentCT signal thresholding (−950 HU)Quantitative, possibly automated
AirwaysCT visual assessment of wall thickness/intraluminal areaAssociated with exacerbation rate
Small airwaysPRM: insp/exp CT
Emphysema (PRMemph)
Air trapping (PRMfSAD)
fSAD associated with FEV1 decline and higher RV
Emphysema associated with lower DLCO
VasculatureCT image reconstructionQuantitative low-diameter vessels proportion (CSA <5 mm2)

CT: computed tomography; HU: Hounsfield units; PRM: parametric response mapping; insp: inspiratory; exp: expiratory; fSAD: functional small airways disease; FEV1: forced expiratory volume in 1 s; RV: residual volume; DLCO: diffusing capacity of the lung for carbon monoxide; CSA: cross-sectional area.