Document Detail


The influence of lung airways branching structure and diffusion time on measurements and models of short-range 3He gas MR diffusion.
MedLine Citation:
PMID:  23159820     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Hyperpolarized (3)He diffusion experiments have been shown to be sensitive to changes in acinar structure due to emphysematous lung disease. Extracting quantitative information about lung microstructure from the diffusion signal is complicated due its dependence on a number of factors including diffusion time and the complex branching acinar geometry. A theoretical model (cylinder model) has been proposed as a means of estimating acinar airway dimensions from measured diffusivities. This model assumes that the effects of acinar branching geometry and finite airway length upon (3)He diffusion behaviour are negligible. In this work, we use finite element simulations of diffusion in a model of branching alveolar ducts to investigate in detail the effects of acinar branching structure and finite airway length on short-range (3)He diffusion measurements. The results show that branching effects have a significant influence upon (3)He diffusivity, even at short diffusion times. The expressions of the cylinder model theory do not account for significant dependences upon diffusion time, branching geometry and airway length, as a consequence of the oversimplified geometrical model used. The effect of diffusion time on (3)He ADC was also investigated through experiments with healthy human volunteers. The results demonstrate that the cylinder model can produce inaccurate estimates of the airway dimensions as a consequence of incompletely accounting for the diffusion-time dependence in the model equations and confirmed the predicted limitations of the cylinder model for reliable lung morphometry measurements. The results and models presented in this work may help in the development of a more realistic theoretical framework for 'in vivo lung morphometry' using (3)He diffusion MR.
Authors:
Juan Parra-Robles; Jim M Wild
Publication Detail:
Type:  Journal Article     Date:  2012-10-26
Journal Detail:
Title:  Journal of magnetic resonance (San Diego, Calif. : 1997)     Volume:  225     ISSN:  1096-0856     ISO Abbreviation:  J. Magn. Reson.     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-11-26     Completed Date:  2013-05-10     Revised Date:  2014-03-25    
Medline Journal Info:
Nlm Unique ID:  9707935     Medline TA:  J Magn Reson     Country:  United States    
Other Details:
Languages:  eng     Pagination:  102-13     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 Elsevier Inc. All rights reserved.
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MeSH Terms
Descriptor/Qualifier:
Adult
Algorithms
Computer Simulation
Diffusion Magnetic Resonance Imaging / methods*
Finite Element Analysis
Helium / diagnostic use*
Humans
Lung / anatomy & histology*,  metabolism*
Models, Statistical
Phantoms, Imaging
Reproducibility of Results
Young Adult
Chemical
Reg. No./Substance:
206GF3GB41/Helium
Comments/Corrections
Comment In:
J Magn Reson. 2014 Feb;239:139-42   [PMID:  24314822 ]
J Magn Reson. 2014 Feb;239:143-6   [PMID:  24342570 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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