Table 2 Airway parameters measured and derived using quantitative computed tomography
Measured parametersConfounding factorsDerived parameters
Lumen areaAi

  • Spatial resolution

  • Image noise

  • Inspiration level

Wall area %Aaw/Ao
Wall areaAawPi10√Aaw at a Pi of 10 mm calculated using regression of measured Pi vs measured √Aaw
Total airway areaAo
Wall thicknessT
Internal lumen perimeterPi
Branch angle

  • Contiguous images

  • Spatial resolution

  • Image noise

Segment length% voxels < pre-defined threshold (i.e. -950 HU)