Thin-section CT in patients with cystic fibrosis: Correlation with peak exercise capacity and body mass index

Purpose: To evaluate whether thin-section chest computed tomographic (CT) findings correlate with exercise capacity, body mass index (BMI), dyspnea, and leg discomfort in patients with cystic fibrosis (CF). Materials and Methods: Institutional ethics committee approval was obtained, and patients provided written informed consent. Twenty-two patients ( 13 male and nine female patients; mean age, 22 years +/- 5.9; age range, 17 - 41 years) with stable CF underwent thin-section CT and exercise testing on a cycle ergometer. Three radiologists blinded to the clinical severity of disease and the spirometric findings of all patients independently and randomly scored all scans with a modified Bhalla scoring system. The primary measurement of the outcome of exercise testing was percentage of predicted peak O-2 uptake. Univariate ( Spearman rank correlation) and multivariate analyses were used to compare thin-section CT, clinical ( age, sex, spirometric data, and BMI), and exercise measurements. Results: The correlation between total thin-section CT score and percentage of predicted peak O-2 uptake was stronger than the correlation between the percentage of predicted peak O-2 uptake and any clinical measurement (R = -0.60, P <.01). The thin-section CT structural abnormalities that had the strongest correlation with percentage of predicted peak O-2 uptake were severity of bronchiectasis and presence of sacculations or abscesses ( R = -0.70 and -0.71, respectively; P < .01). Multivariate analysis showed total thin-section CT score to be the only significant predictor of exercise capacity, accounting for 42% of the variance in percentage of predicted peak O-2 uptake. Conclusion: In patients with CF the correlation between thin-section CT score and exercise limitation is stronger than that between spirometry results or BMI and exercise limitation.