• Cystic Fibrosis: Are Volumetric Ultra-Low-Dose Expiratory CT Scans Sufficient for Monitoring Related Lung Disease?

    Radiology: Volume 253: Number 1— October 2009

    Martine Loeve, MD Maarten H. Lequin, MD, PhD Marleen de Bruijne, PhD leneke J. C. Hartmann, MD, PhD Krista Gerbrands, MD Marcel van Straten, PhD Wim C.J. Hop, PhD Harm A.W.M.Tiddens,MD,PhD

    Purpose: To assess whether chest computed tomography (CT) scores from ultra-low-dose end-expiratory scans alone could suffice for assessment of all cystic fibrosis (CF)-related structural lung abnormalities.

    Materials and Methods: In this institutional review board-approved study, 20 pa­tients with CF aged 6-20 years (eight males, 12 females) underwent low-dose end-inspiratory CT and ultra-low-dose end-expiratory CT. Informed consent was obtained. Scans were randomized and scored by using the Brody-U CT scoring system to assess bronchiectasis, airway wall thickening, mucus plugging, and opacities. Scoring was performed by two observers who were blinded to patient identity and clinical information. Mean scores were used for all analyses. Statistical analysis included assessment of intra- and interobserver variability, calculation of intra-class correlation coefficients (ICCs), and Bland-Altman plots.

    Results: Median age was 12.6 years (range, 6.3-20.3 years), me­dian forced expiratory volume in 1 second was 100% (range, 46%-127%) of the predicted value, and median forced vital capacity was 99% (range, 61%-123%) of the predicted value. Very good agreement was observed be­tween end-inspiratory and end-expiratory CT scores for Brody-II total score (ICC = 0.96), bronchiectasis (ICC = 0.98), airway wall thickening (ICC = 0.94), mucus plug­ging (ICC = 0.96), and opacities (ICC = 0.90). Intra- and interobserver agreement were good to very good (ICC range, 0.70-0.98). Bland-Altman plots showed that differ­ences in scores were independent of score magnitude.

    Conclusion: In this pilot study, CT scores from end-expiratory and end-inspiratory CT match closely, suggesting that ultra-low-dose end-expiratory CT alone may be sufficient for monitoring CF-related lung disease. This would help re­duce radiation dose for a single investigation by up to 75%.