Investigation of pulmonary acoustic simulation: comparing airway model generation techniques

Henry, Brian; Dai, Zoujun; Peng, Ying; Mansy, Hansen A.; Sandler, Richard H.; Royston, Thomas J.

doi:10.1117/12.2043643

Cited by 3 publications

(8 citation statements)

References 12 publications

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“…The tree generated from the algorithm was comparable to the geometry extracted from CT [29-31], which showed monopodiality, and is comparable to the dog lung airways [22]. The generated tree morphology also showed similarity with that reported in previous studies [17,26,33]. …”

Section: Discussionsupporting

confidence: 71%

“…Previous algorithms relied on either pure geometric relation [34,36] or theoretical analysis and optimization criteria [32,33,37]. Some of the geometric relations can be used to generate the large airways [34] while others would be mainly appropriate for adding airways to an existing tree of large diameters [37,36].…”

Section: Discussionmentioning

confidence: 99%

“…While the original Murray's law was derived for blood vessels, several studies [33,34] used that law to describe airway trees. Here, a generalized form of Murray's law where the exponent in the law varied [21,33-35] was used.…”

Section: Introductionmentioning

confidence: 99%

“…Another method of generating a branching network is to use constrained constructive optimization (CCO) of a given tree volume [33,37,38]. Here, a perfusion lung volume is selected inside which the branching network will grow.…”

Section: Introductionmentioning

confidence: 99%

“…A branching network created using CCO depends on the number of terminal segments. CCO algorithm can be used to grow terminal branches on top of a preexisting base tree which was extracted using image segmentation from CT or MRI [33]. …”

Section: Introductionmentioning

confidence: 99%

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Generation of Pig Airways using Rules Developed from the Measurements of Physical Airways

Azad

Mansy

2016

J Bioengineer & Biomedical Sci

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Background A method for generating bronchial tree would be helpful when constructing models of the tree for benchtop experiments as well as for numerical modeling of flow or sound propagation in the airways. Early studies documented the geometric details of the human airways that were used to develop methods for generating human airway tree. However, methods for generating animal airway tree are scarcer. Earlier studies suggested that the morphology of animal airways can be significantly different from that of humans. Hence, using algorithms for the human airways may not be accurate in generating models of animal airway geometry. Objective The objective of this study is to develop an algorithm for generating pig airway tree based on the geometric details extracted from the physical measurements. Methods In the current study, measured values of branch diameters, lengths and bifurcation angles and rotation of bifurcating planes were used to develop an algorithm that is capable of generating a realistic pig airway tree. Results The generation relations between parent and daughter branches were found to follow certain trends. The diameters and the length of different branches were dependent on airway generations while the bifurcation angles were primarily dependent on bifurcation plane rotations. These relations were sufficient to develop rules for generating a model of the pig large airways. Conclusion The results suggested that the airway tree generated from the algorithm can provide an approximate geometric model of pig airways for computational and benchtop studies.

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Section: Discussionsupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Generation of Pig Airways using Rules Developed from the Measurements of Physical Airways

Azad

Mansy

2016

J Bioengineer & Biomedical Sci

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Geometric features of pig airways using computed tomography

Azad

Mansy

Gamage

2016

Physiological Reports

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Accurate knowledge of the airway geometry is needed when constructing physical models of the airway tree and for numerical modeling of flow or sound propagation in the airways. Human and animal experiments are conducted to validate these models. Many studies documented the geometric details of the human airways. However, information about the geometry of pig airways is scarcer. Earlier studies suggested that the morphology of animal airways can be significantly different from that of humans. The objective of this study is to measure the airway diameter, length and bifurcation angles in domestic pigs using computed tomography. In this study, lungs of six pigs were imaged, then segmentation software tools were used to extract the geometry of the airway lumen. The airway dimensions were measured from the resulting 3‐D models for the first 24 airway generations. Results showed that the size and morphology of the airways of the six pigs were similar. The trachea diameters were found to be comparable to the typical human adult, but the diameter, length and branching angles of other airways were noticeably different from that of humans. For example, pig airways consistently had an early branching from the trachea that feeds the top right lung lobe and precedes the main carina. This branch is absent in the human airways. The results suggested that the pig airways geometry may not be accurately approximated by human airways and this approximation may contribute to increasing the errors in computational models of the pig chest.

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Pressure Loss and Sound Generated In a Miniature Pig Airway Tree Model

Azad¹

2017

JABB

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Background: Pulmonary auscultation is a common tool for diagnosing various respiratory diseases. Previous studies have documented many details of pulmonary sounds in humans. However, information on sound generation and pressure loss inside animal airways is scarce. Since the morphology of animal airways can be significantly different from human, the characteristics of pulmonary sounds and pressure loss inside animal airways can be different.Objective: The objective of this study is to investigate the sound and static pressure loss measured at the trachea of a miniature pig airway tree model based on the geometric details extracted from physical measurements.Methods: In the current study, static pressure loss and sound generation measured in the trachea was documented at different flow rates of a miniature pig airway tree. Results:Results showed that the static pressure and the amplitude of the recorded sound at the trachea increased as the flow rate increased. The dominant frequency was found to be around 1840-1870 Hz for flow rates of 0.2-0.55 lit/s. Conclusion:The results suggested that the dominant frequency of the measured sounds remained similar for flow rates from 0.20 to 0.55 lit/s. Further investigation is needed to study sound generation under different inlet flow and pulsatile flow conditions. A diaphragm pressure transducer (Model: DP 103, diaphragm: 8-06, Validyne Engineering, CA,) with full scale input of 0.35 cm of water, accuracy of 0.25% of full scale, and sensitivity of about 0.3 V/Pa was used to measure the static pressure at the trachea. The pressure transducer was calibrated using a hot wire anemometer (Model DT-8880, CEM, Shenzhen, China, range: 0.1~25 m/s, resolution: 0.01 m/s, accuracy: ±5% ± 0.1) and a pitot tube (Model: PAA-6-KL, United Sensor Corporation, NH) inside a wind tunnel that has uniform velocity distribution in the test section (except for a thin boundary layer). To calibrate the pressure transducer, the pitot tube was connected to the pressure transducer and placed inside a wind tunnel while the hot wire was placed at the same streamwise location (outside the boundary layer). The measured hot wire velocities at different flow rates were used to calibrate the pressure transducer. Sound was recorded using a probe mic (Model: ER-7C Probe Microphone Series B, Etymotic Research Inc., IL) with a sensitivity: 50mV/ Pascal. The static pressure and sound at the trachea were acquired using LabVIEW (Ver 2015, National Instruments, Austin, TX) with a data acquisition card (Model: NI 9215, National Instruments, Austin, TX, resolution: 0.305 mV). The flow rate was measured by placing the airway model inside a thin airbag of maximum volume of 6liters. The time needed to fill the maximum bag volume was recorded using a stopwatch (resolution: 0.01 second). Flow rate was then calculated using the recorded time and airbag volume. Keywords: ResultsHot wire velocities were plotted against the pressure transducer voltages at different flow rates inside the wind tunnel ( Figure 3). The velo...

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Investigation of pulmonary acoustic simulation: comparing airway model generation techniques

Cited by 3 publications

References 12 publications

Generation of Pig Airways using Rules Developed from the Measurements of Physical Airways

Generation of Pig Airways using Rules Developed from the Measurements of Physical Airways

Geometric features of pig airways using computed tomography

Pressure Loss and Sound Generated In a Miniature Pig Airway Tree Model

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