title: Lung Clearance Index and HRCT are complementary markers of lung abnormalities in young children with CF.
abstract: BACKGROUND
  High resolution computed tomography (HRCT) is a more sensitive tool for detecting early cystic fibrosis (CF) lung disease than either spirometry or plain radiography, but its relationship to other measures of lung function has not been established in young children.
  
  
  OBJECTIVE
  (1) To assess whether the lung clearance index (LCI) derived from multiple breath inert-gas washout (MBW) is as effective as HRCT in identifying pulmonary abnormalities; and (2) explore the relationships between abnormalities detected by HRCT and by spirometry, plethysmography and MBW (collectively, LFTs) in young children with CF.
  
  
  METHODS
  Children with CF underwent LFTs and volumetric HRCT on the same day. Healthy age-matched controls underwent identical LFTs without HRCT. Scans were anonymised, and scored using the Brody-II CT scoring system, to assess for presence and extent of bronchiectasis, airway wall thickening, mucus plugging, and parenchymal opacities.
  
  
  RESULTS
  Assessments were undertaken in 60 children with CF (mean (SD) 7.8 (1.3 years) and 54 healthy controls (7.9 (1.2) y). Among children with CF, 84% (47/56) had abnormal LCI, 58% (27/47) abnormal plethysmographic lung volumes (FRC(pleth) or RV), 35% (21/60) abnormal sRaw and 47% (28/60) abnormal spirometry (FEV1 or FEF(25-75)); whereas HRCT scans were abnormal in 85% (51/60): median total Brody-II score: 9.5% (range 0-51%). Total CT score correlated more strongly with LCI (Spearman correlation = 0.77) than with spirometry (R = -0.43) or any other marker of lung function. Of the nine children with normal LCI, five had abnormalities on HRCT, whereas five children with normal HRCT had raised LCI.
  
  
  CONCLUSIONS
  These results suggest that while LCI and HRCT have similar sensitivity to detect CF lung disease, complimentary information may be gained in individual patients.
authors.affiliation: Department of Paediatric Radiology, Great Ormond Street Hospital for Children NHS Trust, London, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Owens
authors.forename: P
authors.initials: P
authors.lastname: Aurora
authors.forename: S
authors.initials: S
authors.lastname: Stanojevic
authors.forename: A
authors.initials: A
authors.lastname: Bush
authors.forename: A
authors.initials: A
authors.lastname: Wade
authors.forename: C
authors.initials: C
authors.lastname: Oliver
authors.forename: A
authors.initials: A
authors.lastname: Calder
authors.forename: J
authors.initials: J
authors.lastname: Price
authors.forename: S B
authors.initials: SB
authors.lastname: Carr
authors.forename: A
authors.initials: A
authors.lastname: Shankar
authors.forename: Janet
authors.initials: J
authors.lastname: Stocks
mesh_terms: D001724:Birth Weight; D016022:Case-Control Studies; D002648:Child; D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000503:physiopathology; D042241:Early Diagnosis; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008450:Maximal Midexpiratory Flow Rate / Q000502:physiology; D015203:Reproducibility of Results; D012129:Respiratory Function Tests / Q000379:methods; D013147:Spirometry; D014057:Tomography, X-Ray Computed / Q000379:methods; D014797:Vital Capacity / Q000502:physiology