Novel quantitative bronchiectasis scoring technique for chest computed tomography: BEST-CT. A study within the iABC project

Objectives: To develop a sensitive CT outcome measure to phenotype and quantify lung disease in bronchiectasis (BE) patients. Methods: Collection of the most recent CT scan of BE patients with chronic Pseudomonas aeruginosa infection enrolled in the iBEST-1 study, an RCT of inhaled tobramycin. Volumetric CT scans with a slice thickness ≤ 3 mm were included. In the BE scoring technique for CT (BEST-CT), grid cells were annotated on 10 axial slices. Scoring items in hierarchical order: consolidation/ atelectasis, BE with mucus plugging (MP), BE without MP, airway wall thickening (AWT), MP, ground-glass opacities (GGO), emphysema/ bullae, healthy airways, and healthy parenchyma. Low attenuation regions were scored on expiratory scans. Subscores are expressed as median [IQR] as % of total lung volume. CT scans were also scored using the Hartmann method developed for immunodeficiency patients, and 20 scans were rescored for agreement analyses. Results: We collected 99 CT scans, and included 85 CT scans. Median BE was 3.0% [1.4-5.1], MP 2.7% [1.5-6.1], AWT 0.1 [0-0.2], total airway disease (BE + MP + AWT) 6.2% [3.4-11.8], consolidation/ atelectasis 1.5% [0.6-3.2], GGO 0.3% [0.1-1.1], and emphysema/ bullae 0% [0-0] of total lung volume. Besides BE, atelectasis/ consolidation (84/85), MP (83/85), GGO (68/85), and AWT (55/85) were most frequent annotated abnormalities. Emphysema/ bullae were annotated the least often (13/85). To be performed: inter-and intra-observer agreement analyses and comparison with the Hartmann method. Conclusion: BEST-CT is a quantitative scoring method for BE. Subscores can be used for phenotyping and as outcome measures in clinical trials.