Rui Carlos Sá1, Kirby L Zeman2, William D Bennett2, G Kim Prisk1,3, Chantal Darquenne1. 1. 1 Pulmonary Imaging Laboratory, Department of Medicine, University of California , San Diego, La Jolla, California. 2. 2 Department of Medicine, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina. 3. 3 Pulmonary Imaging Laboratory, Department of Radiology, University of California , San Diego, La Jolla, California.
Abstract
BACKGROUND: To quantify the relationship between regional lung ventilation and coarse aerosol deposition in the supine healthy human lung, we used oxygen-enhanced magnetic resonance imaging and planar gamma scintigraphy in seven subjects. METHODS: Regional ventilation was measured in the supine posture in a 15 mm sagittal slice of the right lung. Deposition was measured by using planar gamma scintigraphy (coronal scans, 40 cm FOV) immediately postdeposition, 1 hour 30 minutes and 22 hours after deposition of 99mTc-labeled particles (4.9 μm MMAD, GSD 2.5), inhaled in the supine posture (flow 0.5 L/s, 15 breaths/min). The distribution of retained particles at different times was used to infer deposition in different airway regions, with 22 hours representing alveolar deposition. The fraction of total slice ventilation per quartile of lung height from the lung apex to the dome of the diaphragm at functional residual capacity was computed, and co-registered with deposition data-apices aligned-using a transmission scan as reference. The ratio of fractional alveolar deposition to fractional ventilation of each quartile (r) was used to evaluate ventilation and deposition matching (r > 1, regional aerosol deposition fraction larger than regional ventilation fraction). RESULTS: r was not significantly different from 1 for all regions (1.04 ± 0.25, 1.08 ± 0.22, 1.03 ± 0.17, 0.92 ± 0.13, apex to diaphragm, p > 0.40) at the alveolar level (r22h). For retention times r0h and r1h30, only the diaphragmatic region at r1h30 differed significantly from 1. CONCLUSIONS: These results support the hypothesis that alveolar deposition is directly proportional to ventilation for ∼5 μm particles that are inhaled in the supine posture and are consistent with previous simulation predictions that show that convective flow is the main determinant of aerosol transport to the lung periphery.
BACKGROUND: To quantify the relationship between regional lung ventilation and coarse aerosol deposition in the supine healthy human lung, we used oxygen-enhanced magnetic resonance imaging and planar gamma scintigraphy in seven subjects. METHODS: Regional ventilation was measured in the supine posture in a 15 mm sagittal slice of the right lung. Deposition was measured by using planar gamma scintigraphy (coronal scans, 40 cm FOV) immediately postdeposition, 1 hour 30 minutes and 22 hours after deposition of 99mTc-labeled particles (4.9 μm MMAD, GSD 2.5), inhaled in the supine posture (flow 0.5 L/s, 15 breaths/min). The distribution of retained particles at different times was used to infer deposition in different airway regions, with 22 hours representing alveolar deposition. The fraction of total slice ventilation per quartile of lung height from the lung apex to the dome of the diaphragm at functional residual capacity was computed, and co-registered with deposition data-apices aligned-using a transmission scan as reference. The ratio of fractional alveolar deposition to fractional ventilation of each quartile (r) was used to evaluate ventilation and deposition matching (r > 1, regional aerosol deposition fraction larger than regional ventilation fraction). RESULTS: r was not significantly different from 1 for all regions (1.04 ± 0.25, 1.08 ± 0.22, 1.03 ± 0.17, 0.92 ± 0.13, apex to diaphragm, p > 0.40) at the alveolar level (r22h). For retention times r0h and r1h30, only the diaphragmatic region at r1h30 differed significantly from 1. CONCLUSIONS: These results support the hypothesis that alveolar deposition is directly proportional to ventilation for ∼5 μm particles that are inhaled in the supine posture and are consistent with previous simulation predictions that show that convective flow is the main determinant of aerosol transport to the lung periphery.
Entities:
Keywords:
coarse aerosol deposition; human lung; multimodal imaging; ventilation
Authors: Rui Carlos Sá; Matthew V Cronin; A Cortney Henderson; Sebastiaan Holverda; Rebecca J Theilmann; Tatsuya J Arai; David J Dubowitz; Susan R Hopkins; Richard B Buxton; G Kim Prisk Journal: J Appl Physiol (1985) Date: 2010-10-07
Authors: Joaquim de Paula Ribeiro; Ana Cristina Kalb; Sabrina de Bastos Maya; Adriana Gioda; Pablo Elias Martinez; José Maria Monserrat; Braulio D Jiménez-Vélez; Carolina Rosa Gioda Journal: Environ Sci Pollut Res Int Date: 2019-10-15 Impact factor: 4.223