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Lung growth in infants and toddlers assessed by multi-slice computed tomography
Laxmi Rao1, Christina Tiller, Cathy Coates
1Department of Pediatrics, James Whitcomb Riley Hospital for Children, Herman B. Wells Center for Pediatric Research, Indiana University, Indianapolis, IN 46202-5225, USA.
Insights
Infant lung growth involves adding new alveoli, not just expanding existing ones. Central airways also grow proportionally in infants and toddlers, aiding in the assessment of arrested lung development.
Area of Science:
- Pediatric pulmonology
- Thoracic imaging
- Lung development
Background:
- Postnatal lung development evaluation traditionally relies on limited autopsy data.
- Uncertainty exists regarding alveolarization completion and conducting airway proportionality in infants.
Purpose of the Study:
- To assess in vivo lung growth and development in infants and toddlers.
- To evaluate alveolarization and conducting airway proportionality using multislice computed tomography.
Main Methods:
- Low-dose volumetric high-resolution computed tomography (CT) was performed on 38 infants and toddlers (17-142 weeks).
- Imaging was conducted at a standardized inflation pressure (20 cm H2O) during a respiratory pause.
- Lung volume, weight, and airway dimensions (trachea and next 3-4 generations) were analyzed.
Main Results:
- Lung volume, air volume, and tissue volume increased linearly with body length.
- Lung parenchyma components (air and tissue) grew at a constant, proportional rate.
- Airway caliber decreased with increasing generation but grew proportionally with body length.
Conclusions:
- In vivo CT suggests lung parenchyma growth occurs via alveolar addition, maintaining a constant air-to-tissue volume ratio.
- Central conducting airways demonstrate proportional growth in infants and toddlers.
- Findings are crucial for evaluating conditions of arrested lung development.
Rationale And Objectives:
Postnatal lung growth and development have primarily been evaluated from a very limited number of autopsied lungs, but it remains unclear whether alveolarization of the lung is complete during infancy and whether the conducting airways grow proportionately. The purpose of this study was to evaluate lung growth and development in vivo in infants and toddlers using multislice computed tomography.
Materials And Methods:
Thirty-eight subjects (14 male, 24 female) aged 17 to 142 weeks underwent low-dose volumetric high-resolution computed tomographic imaging at an inflation pressure of 20 cm H(2)O during an induced respiratory pause. Lung volume and weight were determined, as well as airway dimensions (inner and outer area and wall area) for the trachea and the next three to four generations.
Results:
Lung volume, air volume, and tissue volume increased linearly with body length. The air and tissue components of the lung parenchyma increased at a constant rate with each other. In addition, airway caliber decreased with increasing generation from the trachea into each lobe. Airway caliber was also correlated with body length; however, there was no interaction effect between airway generation and body length on transformed airway size.
Conclusions:
In vivo assessment suggests that the growth of the lung parenchyma in infants and toddlers occurred with a constant relationship between air volume and lung tissue, which is consistent with lung growth occurring primarily by the addition of alveoli rather than the expansion of alveoli. In addition, the central conducting airways grow proportionately in infants and toddlers. This information may be important for evaluating subjects with arrested lung development.
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