title: Quantitative CT characterization of pediatric lung development using routine clinical imaging.
abstract: BACKGROUND
  The use of quantitative CT analysis in children is limited by lack of normal values of lung parenchymal attenuation. These characteristics are important because normal lung development yields significant parenchymal attenuation changes as children age.
  
  
  OBJECTIVE
  To perform quantitative characterization of normal pediatric lung parenchymal X-ray CT attenuation under routine clinical conditions in order to establish a baseline comparison to that seen in pathological lung conditions.
  
  
  METHODS
  We conducted a retrospective query of normal CT chest examinations in children ages 0-7 years from 2004 to 2014 using standard clinical protocol. During these examinations semi-automated lung parenchymal segmentation was performed to measure lung volume and mean lung attenuation.
  
  
  RESULTS
  We analyzed 42 CT examinations in 39 children, ages 3 days to 83 months (mean ± standard deviation [SD] = 42 ± 27 months). Lung volume ranged 0.10-1.72 liters (L). Mean lung attenuation was much higher in children younger than 12 months, with values as high as -380 Hounsfield units (HU) in neonates (lung volume 0.10 L). Lung volume decreased to approximately -650 HU by age 2 years (lung volume 0.47 L), with subsequently slower exponential decrease toward a relatively constant value of -860 HU as age and lung volume increased.
  
  
  CONCLUSIONS
  Normal lung parenchymal X-ray CT attenuation decreases with increasing lung volume and age; lung attenuation decreases rapidly in the first 2 years of age and more slowly thereafter. This change in normal lung attenuation should be taken into account as quantitative CT methods are translated to pediatric pulmonary imaging.
authors: Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA.
authors: Jill M
authors: JM
authors: Stein
authors: Center for Pulmonary Imaging Research, Pulmonary Medicine & Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors: Laura L
authors: LL
authors: Walkup
authors: Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA.
authors: Alan S
authors: AS
authors: Brody
authors: Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA.
authors: Robert J
authors: RJ
authors: Fleck
authors: Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA. Jason.Woods@cchmc.org.|Center for Pulmonary Imaging Research, Pulmonary Medicine & Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA. Jason.Woods@cchmc.org.
authors: Jason C
authors: JC
authors: Woods
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008168:Lung / Q000000981:diagnostic imaging* / Q000254:growth & development*; D008176:Lung Volume Measurements; D008297:Male; D013902:Radiography, Thoracic; D012016:Reference Values; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Children; Computed tomography; Lung attenuation; Lungs; Normal