Of the two observers, one observer (J.M.) was a senior chest radiologist with > 20 years experience. The other observer (J.D.) was a thoracic clinical fellow in chest radiology with 2 years experience scoring HRCT. A consensus meeting was held prior to formal scoring to standardize scoring between observers. HRCT scans were scored over a 2-week time period.
Images were scored using a modified Bhalla scoring system. Modifications included additional HRCT abnormalities described in CF lung disease since the original publication by Bhalla et al. Abnormalities were defined according to recommendations of the nomenclature committee of the Fleischner society. Bronchiectasis was defined as a bronchus with an internal diameter larger then its accompanying pulmonary artery, lack of tapering of the bronchial lumen for > 2 cm, and visualization of a bronchus within 1 cm of the costal pleura. Peribronchial thickening was defined by a bronchial wall > 1 mm in thickness. Mucus plugging was identified by visualizing plugs in large airways or by the presence of tree-in-bud peripherally.
Sacculations were defined when dilated bronchi had a cystic or saccular appearance. A bulla was defined as a round, focal airspace > 1 cm in diameter, demarcated by a thin wall. Emphysema was defined as areas of decreased attenuation with disruption of the underlying vascular pattern and absence of well-defned walls. Consolidation was identified when increased lung opacification was detected that obscured the underlying parenchyma. We modified the score by including an assessment of acinar nodules, thickening of interlobular septa, ground glass and mosaic perfusion on inspiratory images, and air trapping on expiratory images, as these changes are commonly seen and generally included in contemporary scoring systems for CF lung disease. A nodule was defined as a round opacity at least moderately well marginated and not more than 3 cm. A septal line was defined as a thin line corresponding to an interlobular septum. Ground-glass opacity was identified when increased lung opacification was detected but did not obscure the underlying parenchyma.