FSI Analysis of a Healthy and a Stenotic Human Trachea Under Impedance-Based Boundary Conditions

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
M. Malvè ◽  
A. Pérez del Palomar ◽  
S. Chandra ◽  
J. L. López-Villalobos ◽  
A. Mena ◽  
...  
Keyword(s):  
Solid Material ◽  
Flow Patterns ◽  
Bronchial Tree ◽  
Tracheal Wall ◽  
Computed Tomography Images ◽  
Wall Deformation ◽  
Human Trachea ◽  
Fluid Solid Interaction ◽  
Fractal Network

In this work, a fluid-solid interaction (FSI) analysis of a healthy and a stenotic human trachea was studied to evaluate flow patterns, wall stresses, and deformations under physiological and pathological conditions. The two analyzed tracheal geometries, which include the first bifurcation after the carina, were obtained from computed tomography images of healthy and diseased patients, respectively. A finite element-based commercial software code was used to perform the simulations. The tracheal wall was modeled as a fiber reinforced hyperelastic solid material in which the anisotropy due to the orientation of the fibers was introduced. Impedance-based pressure waveforms were computed using a method developed for the cardiovascular system, where the resistance of the respiratory system was calculated taking into account the entire bronchial tree, modeled as binary fractal network. Intratracheal flow patterns and tracheal wall deformation were analyzed under different scenarios. The simulations show the possibility of predicting, with FSI computations, flow and wall behavior for healthy and pathological tracheas. The computational modeling procedure presented herein can be a useful tool capable of evaluating quantities that cannot be assessed in vivo, such as wall stresses, pressure drop, and flow patterns, and to derive parameters that could help clinical decisions and improve surgical outcomes.

Preservation of sickle cell blood-flow patterns during MR imaging: an in vivo study

1988 ◽  
Vol 151 (1) ◽  
pp. 139-141 ◽  
Author(s):  
AS Brody ◽  
SH Embury ◽  
WC Mentzer ◽  
ML Winkler ◽  
CA Gooding
Keyword(s):  
Blood Flow ◽  
Mr Imaging ◽  
Sickle Cell ◽  
Flow Patterns ◽  
In Vivo Study ◽  
Blood Flow Patterns

scholarly journals Synchrotron-based dynamic computed tomography of tissue motion for regional lung function measurement

2012 ◽  
Vol 9 (74) ◽  
pp. 2213-2224 ◽  
Author(s):  
Stephen Dubsky ◽  
Stuart B. Hooper ◽  
Karen K. W. Siu ◽  
Andreas Fouras
Keyword(s):  
Computed Tomography ◽  
Lung Function ◽  
Ct Scanning ◽  
Bronchial Tree ◽  
Dynamic Computed Tomography ◽  
Lung Inflation ◽  
Regional Dynamics ◽  
Lung Expansion ◽  
Regional Lung

During breathing, lung inflation is a dynamic process involving a balance of mechanical factors, including trans-pulmonary pressure gradients, tissue compliance and airway resistance. Current techniques lack the capacity for dynamic measurement of ventilation in vivo at sufficient spatial and temporal resolution to allow the spatio-temporal patterns of ventilation to be precisely defined. As a result, little is known of the regional dynamics of lung inflation, in either health or disease. Using fast synchrotron-based imaging (up to 60 frames s −1 ), we have combined dynamic computed tomography (CT) with cross-correlation velocimetry to measure regional time constants and expansion within the mammalian lung in vivo . Additionally, our new technique provides estimation of the airflow distribution throughout the bronchial tree during the ventilation cycle. Measurements of lung expansion and airflow in mice and rabbit pups are shown to agree with independent measures. The ability to measure lung function at a regional level will provide invaluable information for studies into normal and pathological lung dynamics, and may provide new pathways for diagnosis of regional lung diseases. Although proof-of-concept data were acquired on a synchrotron, the methodology developed potentially lends itself to clinical CT scanning and therefore offers translational research opportunities.

scholarly journals In vivo analysis and three-dimensional visualisation of blood flow patterns at vascular end-to-side anastomoses

1995 ◽  
Vol 10 (2) ◽  
pp. 168-181 ◽  
Author(s):  
N.H. Staalsen ◽  
M. Ulrich ◽  
W.Y. Kim ◽  
E.M. Pedersen ◽  
T.V. How ◽  
...  
Keyword(s):  
Blood Flow ◽  
Three Dimensional ◽  
Flow Patterns ◽  
In Vivo Analysis ◽  
Blood Flow Patterns

scholarly journals Modeling Airflow and Particle Deposition in a Human Acinar Region

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Arun V. Kolanjiyil ◽  
Clement Kleinstreuer
Keyword(s):  
Flow Pattern ◽  
Particle Deposition ◽  
Current Model ◽  
Particle Diameter ◽  
Particle Simulation ◽  
Present System ◽  
Alveolar Region ◽  
Recirculating Flow ◽  
Wall Deformation

The alveolar region, encompassing millions of alveoli, is the most vital part of the lung. However, airflow behavior and particle deposition in that region are not fully understood because of the complex geometrical structure and intricate wall movement. Although recent investigations using 3D computer simulations have provided some valuable information, a realistic analysis of the air-particle dynamics in the acinar region is still lacking. So, to gain better physical insight, a physiologically inspired whole acinar model has been developed. Specifically, air sacs (i.e., alveoli) were attached as partial spheroids to the bifurcating airway ducts, while breathing-related wall deformation was included to simulate actual alveolar expansion and contraction. Current model predictions confirm previous notions that the location of the alveoli greatly influences the alveolar flow pattern, with recirculating flow dominant in the proximal lung region. In the midalveolar lung generations, the intensity of the recirculating flow inside alveoli decreases while radial flow increases. In the distal alveolar region, the flow pattern is completely radial. The micron/submicron particle simulation results, employing the Euler–Lagrange modeling approach, indicate that deposition depends on the inhalation conditions and particle size. Specifically, the particle deposition rate in the alveolar region increases with higher inhalation tidal volume and particle diameter. Compared to previous acinar models, the present system takes into account the entire acinar region, including both partially alveolated respiratory bronchioles as well the fully alveolated distal airways and alveolar sacs. In addition, the alveolar expansion and contraction have been calculated based on physiological breathing conditions which make it easy to compare and validate model results with in vivo lung deposition measurements. Thus, the current work can be readily incorporated into human whole-lung airway models to simulate/predict the flow dynamics of toxic or therapeutic aerosols.

scholarly journals In vivo estimation of coronary mechanical wall deformation and its relation to plaque formation

2003 ◽  
Author(s):  
M. Roberts ◽  
S.P. Corney ◽  
A. Thomson ◽  
J. Bashford ◽  
A.G. Kan
Keyword(s):  
Plaque Formation ◽  
Wall Deformation

Spiral Laminar Flow in Vivo

1996 ◽  
Vol 91 (1) ◽  
pp. 17-21 ◽  
Author(s):  
P. A. Stonebridge ◽  
P. R. Hoskins ◽  
P.L. Allan ◽  
J. F. F. Belch
Keyword(s):  
Blood Flow ◽  
Reverse Flow ◽  
Arterial Disease ◽  
Flow Patterns ◽  
Endothelial Damage ◽  
Arterial Blood Flow ◽  
Arterial Tree ◽  
Arterial Blood ◽  
Blood Flow Patterns

1. Blood flow patterns are poorly understood despite their impact on arterial disease. There have been few measurements in vivo of the three-dimensional blood flow patterns; we present the results of such studies using a new non-invasive in-vivo method of examining biplanar arterial blood flow patterns. 2. Multiple colour Doppler ultrasound directional velocity images were obtained at two different beam target angles from the artery in the plane perpendicular to its axis. Ensemble average images were constructed; the absolute velocity and direction were calculated by compounding the left and right averaged images. Simple directional, non-directional velocity and vector maps were constructed. 3. Flow patterns were sampled in 11 healthy male volunteers at four points of the pulse cycle; peak systole, systolic downswing, diastolic reverse flow and diastolic forward flow and at three sites; the right common and distal superficial femoral and the left common femoral arteries. 4. Stable rotational flow was observed in all subjects, the direction of rotation varying between sides and individuals. 5. There are theoretical advantages to spiral laminar blood flow; the forward-directed, rotationally induced stability and reduction of laterally directed forces may reduce turbulence in the tapering branching arterial tree and at stenoses and have a beneficial effect on mechanisms of endothelial damage and repair.

Vortical Flow Feature Recognition: A Topological Study of In Vivo Flow Patterns Using MR Velocity Mapping

1998 ◽  
Vol 22 (4) ◽  
pp. 577-586 ◽  
Author(s):  
Guang-Zhong Yang ◽  
Raad H. Mohiaddin ◽  
Philip J. Kilner ◽  
David N. Firmin
Keyword(s):  
Feature Recognition ◽  
Flow Patterns ◽  
Vortical Flow ◽  
Velocity Mapping ◽  
Flow Feature

scholarly journals Morphometric Characteristics of the Portal Vein According to Multispiral Computed Tomography

2021 ◽  
Vol 9 (4) ◽  
pp. 38-44
Author(s):  
A. V. Kolsanov ◽  
M. N. Myakotnykh ◽  
A. A. Mironov ◽  
E. I. Kanaev
Keyword(s):  
Computed Tomography ◽  
Portal Vein ◽  
Abdominal Cavity ◽  
Age Groups ◽  
The Elderly ◽  
Morphometric Characteristics ◽  
Portal Vein Branch ◽  
Computed Tomography Images ◽  
Linear Dimensions

The article discusses the variability of the linear dimensions of the portal vein depending on gender and age. In modern foreign and Russian literature, there is no uniform information about the variant portal vein anatomy. Data on the extreme forms and on the range of anatomical differences in the portal vein vary considerably. All this requires the need for a more detailed study of the morphometric characteristics of the portal vein branch. Computed tomography, in contrast to dissection on a corpse, allows an in vivo study of various morphometric characteristics of the portal vein.The aim of the study is to identify patterns of variability in the linear dimensions of the portal vein in persons of different sex and age.Material and methods. The study material consisted of multispiral computed tomography images of the abdominal cavity with contrast enhancement taken in 100 patients. The study included results of 56 men and 44 women, divided into 4 age groups: 1) first mature age, 2) second mature age, 3) the elderly, 4) the senile. The length of the portal vein was measured between the angle formed at the junction of the superior mesenteric and splenic veins and the angle formed by the branches of the portal vein at the hepatic hilum. The diameter of the vessel was measured at the midpoint of the distance between the proximal and distal points.Results. The length of the portal vein in the general sample was 66.45±8.49 mm, and its diameter was 11.84±1.93 mm. In women, the length of the portal vein was 64.37±6.6 mm, and its diameter was 11.33±1.83 mm, respectively. In men, both the length and diameter of the black vein were significantly greater than in women and constituted 68.09±9.4 mm and 12.24±1.91 mm, respectively. No statistically significant correlation of the studied parameters with age was detected.

Paradoxical conducting airway responses and heterogeneous regional ventilation after histamine inhalation in rabbit studied by synchrotron radiation CT

2009 ◽  
Vol 106 (6) ◽  
pp. 1949-1958 ◽  
Author(s):  
Sam Bayat ◽  
Liisa Porra ◽  
Heikki Suhonen ◽  
Pekka Suortti ◽  
Anssi R. A. Sovijärvi
Keyword(s):  
Synchrotron Radiation ◽  
Bronchial Tree ◽  
Regional Ventilation ◽  
Conducting Airway ◽  
Ventilation Heterogeneity ◽  
Airway Response ◽  
Poor Ventilation ◽  
Airway Responses ◽  
Conducting Airways

We studied both central conducting airway response and changes in the distribution of regional ventilation induced by inhaled histamine in healthy anesthetized and mechanically ventilated rabbit using a novel xenon-enhanced synchrotron radiation computed tomography (CT) imaging technique, K-edge subtraction imaging (KES). Images of specific ventilation were obtained using serial KES during xenon washin, in three axial lung slices, at baseline and twice after inhalation of histamine aerosol (50 or 125 mg/ml) in two groups of animals ( n = 6 each). Histamine inhalation caused large clustered areas of poor ventilation, characterized by a drop in average specific ventilation (sV̇m), but an increase in sV̇m in the remaining lung zones indicating ventilation redistribution. Ventilation heterogeneity, estimated as coefficient of variation (CV) of sV̇m significantly increased following histamine inhalation. The area of ventilation defects and CV were significantly larger with the higher histamine dose. In conducting airways, histamine inhalation caused a heterogeneous airway response combining narrowing and dilatation in individual airways of different generations, with the probability for constriction increasing peripherally. This finding provides further in vivo evidence that airway reactivity in response to inhaled histamine is complex and that airway response may vary substantially with location within the bronchial tree.

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