Table 1

CT_BO scoring system for one lobe*

CT abnormality	Score
CT abnormality	0	1	2	3
Bronchiectasis: peripheral is 1–2 cm from the costal/diaphragmatic pleura or abutting the mediastinal pleura; B, diameter of bronchial lumen; V, diameter of accompanying pulmonary artery.
Mucus plugging: central = plugging in identifiable bronchi; peripheral = centrilobular nodules and tree in bud.
Airway wall thickening: mild = >2 mm in hilum, 1 mm centrally and 0.5 mm peripherally.
Scores for each abnormality were calculated according to Brody et al*.¹⁹ Figure 1 shows images corresponding to the scoring system abnormalities.
Bronchiectasis
Central lung (extent)	Absent	<33%	33–67%	>67%
Peripheral lung (extent)	Absent	<33%	33–67%	>67%
Size of largest	Absent	B <2 V	B 2–3 V	B >3 V
Size of average	Absent	B <2 V	B 2–3 V	B >3 V
Mucus plugging
Central (extent)	Absent	<33%	33–67%	>67%
Peripheral (extent)	Absent	<33%	33–67%	>67%
Airway wall thickening
Severity	Absent	Mild	0.5–1 V	>1 V
Central lung (extent)	Absent	<33%	33–67%	>67%
Peripheral lung (extent)	Absent	<33%	33–67%	>67%
Consolidation (extent)	Absent	<33%	33–67%	>67%
Mosaic pattern (extent): inspiratory CT scan finding	Absent	<33%	33–67%	>67%
Air trapping (extent): expiratory CT scan finding	Absent	<33%	33–67%	>67%