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Sensitivity of nasal airflow variables computed via computational fluid dynamics to the computed tomography segmentation threshold. PLoS One 2018;13(11):e0207178

Date

11/18/2018

Pubmed ID

30444909

Pubmed Central ID

PMC6239298

DOI

10.1371/journal.pone.0207178

Scopus ID

2-s2.0-85056695624   3 Citations

Abstract

Computational fluid dynamics (CFD) allows quantitative assessment of transport phenomena in the human nasal cavity, including heat exchange, moisture transport, odorant uptake in the olfactory cleft, and regional delivery of pharmaceutical aerosols. The first step when applying CFD to investigate nasal airflow is to create a 3-dimensional reconstruction of the nasal anatomy from computed tomography (CT) scans or magnetic resonance images (MRI). However, a method to identify the exact location of the air-tissue boundary from CT scans or MRI is currently lacking. This introduces some uncertainty in the nasal cavity geometry. The radiodensity threshold for segmentation of the nasal airways has received little attention in the CFD literature. The goal of this study is to quantify how uncertainty in the segmentation threshold impacts CFD simulations of transport phenomena in the human nasal cavity. Three patients with nasal airway obstruction were included in the analysis. Pre-surgery CT scans were obtained after mucosal decongestion with oxymetazoline. For each patient, the nasal anatomy was reconstructed using three different thresholds in Hounsfield units (-800HU, -550HU, and -300HU). Our results demonstrate that some CFD variables (pressure drop, flowrate, airflow resistance) and anatomic variables (airspace cross-sectional area and volume) are strongly dependent on the segmentation threshold, while other CFD variables (intranasal flow distribution, surface area) are less sensitive to the segmentation threshold. These findings suggest that identification of an optimal threshold for segmentation of the nasal airway from CT scans will be important for good agreement between in vivo measurements and patient-specific CFD simulations of transport phenomena in the nasal cavity, particularly for processes sensitive to the transnasal pressure drop. We recommend that future CFD studies should always report the segmentation threshold used to reconstruct the nasal anatomy.

Author List

Cherobin GB, Voegels RL, Gebrim EMMS, Garcia GJM

Author

Guilherme Garcia PhD Assistant Professor in the Biomedical Engineering department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Adult
Computer Simulation
Female
Humans
Hydrodynamics
Imaging, Three-Dimensional
Magnetic Resonance Imaging
Male
Middle Aged
Models, Anatomic
Nasal Cavity
Nasal Obstruction
Respiratory Mechanics
Tomography, X-Ray Computed
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a