Table 1. Computed tomography (CT) scoring system for assessment of Mycobacterium avium complex (MAC) disease extent.

	Score
CT Findings (Maximum Score Possible)	0 Points	1 Point	2 Points	3 Points
Bronchiectasis (9 points)
Severity*	Absent	Mild	Moderate	Severe
Extent, no. of involved segments	Absent	1–5	6–9	>9
Mucus plugging, no. of involved segments	Absent	1–5	6–9	>9
Cellular bronchiolitis (6 points)
Severity†	Absent	Mild	Moderate	Severe
Extent, no. of involved segments	Absent	1–5	6–9	>9
Cavity (9 points)	Absent
Diameter, cm	Absent	<3	3–5	>5
Wall thickness, mm	Absent	<1	1–5	>5
Extent, no. of cavities	Absent	1–3	4–5	>5
Nodule extent, no. of involved segments(3 points)	Absent	1–5	6–9	>9
Consolidation extent, no. of involved segments(3 points)	Absent	<3	3–5	>5

*Mild = bronchus diameter greater than adjacent vessel diameter; moderate = bronchus diameter two to three times vessel diameter; severe = bronchus diameter greater than three times vessel diameter.

†Mild = peripheral lung, 1 cm from pleura; moderate = involvement greater than 1–3 cm from pleura; severe = extending to central lung.