Chest
Volume 144, Issue 4, October 2013, Pages 1193-1198
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Original Research
Genetic and Developmental Disorders
Assessment of Early Bronchiectasis in Young Children With Cystic Fibrosis Is Dependent on Lung Volume

https://doi.org/10.1378/chest.12-2589Get rights and content

Objective

The aim of this study was to determine whether assessment of early CT scan-detected bronchiectasis in young children with cystic fibrosis (CF) depends on lung volume.

Methods

This study, approved by the hospital ethics committee, included 40 young children with CF from a newborn screened population contributing paired volume-controlled inspiratory and expiratory volumetric chest CT scans acquired under general anesthesia while clinically stable. Bronchiectasis was assessed with a semiquantitative CT scan score in inspiration and expiration, and the sensitivity of the expiratory CT scan to detect bronchiectasis was compared with the inspiratory CT scan by sensitivity and intraclass correlation coefficient analysis and Bland-Altman plots. Matched inspiratory and expiratory airway-vessel measurements were obtained in a subset of 10 children, and the relationship between lung volume and airway:vessel ratio after adjusting for age and vessel size was examined with the use of a linear regression model with generalized estimating equations. The number of visible airways in inspiration and expiration was compared in all 40 children by Wilcoxon signed rank test.

Results

Expiratory scans had poor sensitivity (0.46) to detect bronchiectasis, underestimating disease extent (P < .001). Airway:vessel ratios were consistently higher in inspiration, independent of age and vessel size (P < .001), with significantly more airways visible in inspiration than in expiration, independent of age (median, 71 vs 28, respectively; P < .001).

Conclusions

In young children with CF, radiologic assessment of early bronchiectasis with chest CT scan depends on lung volume; thus, expiratory scans may not be appropriate for evaluating bronchiectasis in this population. Lung volume during CT image acquisition should be standardized to evaluate airway dimensions in young children.

Section snippets

Study Population

This study included 40 consecutive subjects with CF aged 1 to 5 years who underwent a volumetric inspiratory and expiratory chest CT scan performed under general anesthesia while clinically stable as part of an early surveillance program approved by the local hospital ethics committee at Princess Margaret Hospital for Children in Australia (approval number 1762/EPP). These children were the first 40 children age 1 to 5 years to undergo paired inspiratory and expiratory volumetric chest CT scans

Semiquantitative CT Scores

Intraclass correlation coefficients for within-observer agreement for bronchiectasis were 0.79 (scorer 1) and 0.95 (scorer 2) for inspiratory scans and 0.94 (scorer 1) and 0.95 (scorer 2) for expiratory scans, and between-observer agreements were 0.78 for inspiratory scans and 0.92 for expiratory scans, indicating good to excellent agreement for these semiquantitative scores. The sensitivity, specificity, and positive and negative predictive values for the expiratory scans vs the inspiratory

Discussion

This study demonstrates that assessment of early bronchiectasis in infants and young children with CF by chest CT scan depends on lung volume, providing strong support for standardization of lung volume in studies evaluating airway dimensions by chest CT scan. With the use of limited-slice chest CT scan, Long et al4 demonstrated that end-inspiratory images obtained through a controlled ventilation technique are more sensitive to detect bronchiectasis than images obtained during quiet breathing

Acknowledgments

Author contributions: Dr Mott had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Mott: contributed to the study concept and design; data acquisition, analysis, and interpretation; statistical analysis; and preparation, revision, and final approval of the manuscript.

Dr Graniel: contributed to the data acquisition and revision and final approval of the manuscript.

Ms Park: contributed to the data

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    A total of 4182 papers were identified. After screening all titles and abstracts, 972 papers were selected for full text evaluation, and 122 were included in the analysis [5–126] Criteria for radiological diagnosis of bronchiectasis across 122 studies are reported in Table 3.

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Profs Tiddens and Stick contributed equally to this manuscript as senior authors.

Part of this article has been presented in abstract form (Mott L, Gonzalez-Graniel K, Murray C, Sly P, Tiddens H, Stick S; AREST CF. Eur Respir J. 2011;38:848s and Mott L, Graniel K, Park J, et al; AREST CF. Respirology. 2012:17:56).

Funding/Support: The AREST CF research program is funded by the Cystic Fibrosis Foundation Therapeutics, Inc [Sly040A, Stick090A]; the Australian Cystic Fibrosis Research Trust; and the National Health and Medical Research Council [513730], Australia. Dr Mott was supported by a short-term research fellowship from the European Respiratory Society to travel to Rotterdam, The Netherlands, to commence this study and was supported in her PhD studies by the National Health and Medical Research Council, the University of Western Australia, the Cystic Fibrosis Association of Western Australia, and the Australian Cystic Fibrosis Research Trust. Dr Graniel was supported by a grant from The Nederlandse Cystic Fibrosis Stichting.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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The members of the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) can be found at www.arestcf.org.

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