High-resolution CT in the acute exacerbation of cystic fibrosis: evaluation of acute findings, reversibility of those findings, and clinical correlation.

Abstract

The aims of this study were threefold: to compare high-resolution CT (HRCT) of adult patients with cystic fibrosis (CF) during acute exacerbations with asymptomatic patients with CF, to evaluate reversibility of HRCT abnormalities after exacerbations, and to correlate HRCT with clinical parameters. Nineteen symptomatic and eight asymptomatic patients were prospectively evaluated by HRCT and pulmonary function tests (PFTs). Symptomatic patients were reassessed 2 weeks after the exacerbation. Studies were independently reviewed by two radiologists using a modified Bhalla scoring system, noting the presence, extent, and severity of bronchiectasis, peribronchial thickening, mucus plugging, and atelectasis or consolidation. Modifications to the Bhalla system included evaluation of the presence and profusion of centrilobular nodules and air-fluid levels within bronchiectatic cavities. The highest possible score was 24 points. Higher scores indicated greater severity. Mosaic perfusion was noted but not included in the modified Bhalla HRCT score. Total modified Bhalla HRCT score and components of the HRCT score were correlated with corresponding PFT parameters. Bronchiectasis, peribronchial thickening, mucus plugging, centrilobular nodules, and mosaic perfusion were identified in symptomatic and asymptomatic patients. Air-fluid levels in bronchiectatic cavities, identified in two patients, represented the only finding limited to acute exacerbation. Reversible findings included air-fluid levels (100%), centrilobular nodules (36%), mucus plugging (33%), and peribronchial thickening (11%). Total HRCT severity scores of symptomatic and asymptomatic patients correlated with forced vital capacity (FVC) (r = .44, p = .01) and forced expiratory volume at 1 sec (FEV1) (r = .34, p = .04). Severity of bronchiectasis correlated with FVC (r = .50, p = .004) and FEV1 (r = .40, p = .02). Mucus plugging and centrilobular nodules did not correlate with PFT parameters. In the symptomatic patients, improvement in HRCT score correlated with changes in FEV1/FVC (r = .39, p = .049). Air-fluid levels in bronchiectatic cavities were the only parenchymal finding shown by HRCT that was limited to the acute exacerbation of CF in our study population. However, this finding was rare, being seen in two of 19 patients. Mucus plugging, centrilobular nodules, and peribronchial thickening were potentially reversible findings in symptomatic patients. HRCT accurately revealed disease severity in patients with CF. We also found that changes in HRCT scores correlated with clinical improvement as determined by PFTs.