Advances in Clinical Application of Numerical Study of Ear and Upper Airway / 医用生物力学

Ear and upper airway are portal organs of human body. Because of their fine and narrow structure, the non-invasive research and the effect of clinical diagnosis and treatment in traditional medicine are always unsatisfactory. With the development of computer technology, numerical simulation has become an effective means of auxiliary research. Numerical simulation can reproduce or evaluate the diagnosis and treatment of ear and upper airway diseases, and it is a powerful means to promote the development of basic medicine and technology of clinical diagnosis and treatment. The application of numerical simulation in relationship between the structure and function of ear and upper airway, the influence of diseases on function, the evaluation of clinical diagnosis and treatment technology， as well as the design of related medical devices were reviewed. The clinical application of numerical research in ear and upper airway was prospected, so as to provide references for the future clinical diagnosis and treatment of ear and upper airway.

The mechanism of sensing postural changes in human ears by numerical simulation / 医用生物力学

Objective To study the general mechanical behavior pattern of sensing angular velocity by 3 pairs of human semicircular canals.Methods Sinusoidal head rotation of a healthy subject was simulated by finite element method to analyze the dynamic responses in the above 3 pairs of canals in the left and right inner ear.Results Compared with the complicated node displacement distribution,the volumetric strain distribution of cupula was regular.Specifically,each pair of cupulae expanded or contracted within the same amplitude with the same response frequency to the angular velocity.The ratio of absolute volumetric strain among the horizontal semicircular canal cupula (HC cupula),the anterior semicircular canal cupula (AC cupula),and the posterior semicircular canal cupula (PC cupula),was approximately 1.00∶0.80 ∶ 1.72,which kept constant.In addition,the volumetric strain of HC cupula was in phase with that of AC cupula,but showing 14.4° out of phase with the angular velocity,and 180° out of phase with that of PC cupula.Conclusions The volumetric strain of cupula can preferably characterize the directional coding function of semicircular canal,and the amplitude,frequency and phase of the cupular volumetric strain can encode those of the stimulated angular velocity,respectively.These results will lay the foundation for establishing quantitative relationship of vestibulo-ocular reflex,and provide theoretical references for quantitative assessment for vestibular function by nystagmus examination.

Establishment of Finite Element Model and Analysis of Airflow Characteristics in Patients with Nasal Structural Abnormalities / 中国医科大学学报

Objective To analyze the airflow characteristics and investigate the relationship of the structure and the function of nasal cavity by the three?dimensional reconstruction of nasal airway of patients with structural abnormalities(nasal septum deviation)and healthy people and the estab?lishment of finite element model by computer. Methods On the basis of CT imaging of the nasal cavity in patients with structural abnormalities(na?sal septum deviation,n=20)and healthy people(n=20),three?dimensional reconstruction of nasal airway was conducted by resurfacing finite ele?ment subdivision to simulate the characteristics of airflow in nasal cavity. Results The airflow mainly went through the commodious side of the nose in patients with nasal septum deviation and the maximum fluence appeared in the middle part of meatus nasi communis. The airway pressure de?creased most significantly in the most flank?curvature part of nasal septum deviation,accounting approximately 79.65%of the total pressure. In healthy people,the bilateral airflow was affected by nasal cycle and was mainly characterized by one nasal cavity,and the maximum fluence was ob?served in the middle and the inferior part of meatus nasi communis. The airway pressure decreased most significantly in limen nasi,accounting ap?proximately 58.78%of the total pressure. Conclusion Numerical modeling of nasal cavity can be used to analyze the relationship between the nasal structural abnormalities and the airflow characteristics,which is a scientific method to analyze the association of nasal structure and function with dis?ease and can be used for pre?and post?operative individual evaluation of operative therapeutic regimen targeting at optimizing airway and altering air?flow distribution.

Numerical research on the deposition of suspended particulate matter in respiratory tract / 中国耳鼻咽喉头颈外科

[ABSTRACT]OBJECTIVETo study the deposition of suspended particles in the respiratory tract during human breathing.METHODSBased on CT data, three dimensional finite element model of an anatomically accurate respiratory tract, including the nasal cavity, oral cavity, pharynx, larynx, trachea and parts of tracheobronchial tree, is established. Numerical analysis for the deposition of suspended particles in the respiratory tract was conducted. RESULTSThe velocity and pressure distributions of airflow in the respiratory tract were obtained, as well as the particles path and their deposition law.CONCLUSION Respiratory tract plays an important role in filtering suspended particles in the air during breathing. The main deposition sites of the particles were at the front of the inferior turbinate and the posterior pharyngeal wall.

Numerical simulation of intranasal airlfow ifeld / 中国耳鼻咽喉头颈外科

[ABSTRACT]OBJECTIVETo explore the basic characters of the airflow-field in Chinese people's nasal cavity by computational fluid dynamics.METHODSThe three-dimensional, finite-element mesh were developed from Spiral CT imaging scans of nose of the 40 healthy Chinese people. Given the following spatial boundaries of the flow field: no-slip condition was imposed at the surface of the nasal airway walls; a standard atmosphere pressure condition was established at the inlet; a velocity vector was specified at the outlet (nasopharynx), which was obtained under the condition of aspiratory flow rate (12 L/min), the full Navier-Stokes and continuity equations were solved to obtain the airflow pattern.RESULTS1. The airflow passed mainly through left or right side of the nasal airway in the whole 40 cases (left 33, right 7),and the volume of air through the main-side is (320±28) ml while non-main-side (180±45) ml. 2. Airflow velocity: airflow of anterior nostrils, internal nostrils, the middle and inferior parts of the total meatus in the main-side were (5.01±2.12) m/s, (7.00±1.75) m/s, (5.08±1.55) m/s, (4.12±1.40) m/s respectively, and those in non-main-side were (2.01±0.94) m/s, (2.40±0.34) m/s, (1.99±1.0) m/s, (2.01±0.65) m/s respectively, which differences between the both sides were of statistical significance (allP0.05); 3. The airflow form appeared to be linear in the middle and inferior parts of the nasal cavity. 4. Velocity in maxillary sinus cavity was almost 0 m/s.CONCLUSIONThe airflow passes mainly through the middle and inferior parts of the meatus with higher velocity in laminar form and airflow of middle meatus, inferior meatus and olfactory cleft are low and the velocity were slow. Besides, airflow in maxillary sinus cavity diffuses free mainly.

Study on the correlation between the ostia diameter changes and airflow characteristics in maxillary sinus / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the relationship between the maxillary sinus flow field, temperature field and the maxillary sinus ostium size, and to provide a reference for endoscopic surgery according to the maxillary sinus scope.</p><p><b>METHODS</b>One case of adult female CT image data was obtained, and used to build a three-dimensional model of nasal cavity and maxillary sinus. Computational fluid dynamics method was used to study the airflow and temperature of the maxillary sinus, as well as the physiological function of the maxillary sinus. Simulation surgery by means of different maxillary sinus diameters (normal, 8 mm, 10 mm, 12 mm and 15 mm) was used to describe the maxillary sinus airflow and temperature change.</p><p><b>RESULTS</b>It was found that by numerical simulation the airflow of maxillary sinus and nasal cavity showed lower speed (average speed 0.062 m/s) than that in the middle nasal meatus (average speed of 3.260 m/s), and the average temperature in the normal maxillary sinus was 34°C, which was higher than that in the middle nasal meatus (temperature 28.7°C). With the increase of the diameter of the maxillary sinus, the air temperature change was not obvious.</p><p><b>CONCLUSIONS</b>The physiological function of the maxillary sinus can be studied through the numerical simulation. With the increase of the ostia diameter of maxillary sinus, the sinus temperature and ventilation is not affected. It provides a reference for quantification of clinical endoscopic maxillary sinus surgery.</p>

Internal boundary parameters identification of human middle ear with neural network / 医用生物力学

Objective To study the method of internal boundary parameters identification of middle ear.Method The numerical model is created using CT technology.Based on Matlab tools,the neural network for identifying internal boundary is proposed.Result The uniform pressure of 105 dB is applied at the outside of the tympanic membrane,and the harmonic analysis is calculated on the model to take the training samples.The internal condition parameters are identified using the good neural network.Conclusions The investiga-tion shows that the inverse method reveals a fast convergence and a high degree of accuracy.

Acoustic rhinometry and acoustic pharyngometry in the modeling of human upper respiratory tract / 生物医学工程学杂志

Acoustic rhinometry and acoustic pharyngometry (AR/P) can quantify the upper airway condition of air draft by drawing a graph plotting the nasal cavity and pharyngeal cavity cross-sectional area. Based on CT medical images of volunteers, a 3-dimensional finite element model of upper respiratory tract was reconstructed by using the method of surface rendering. The veracity of the model was valued by comparison of the relevant areas between the model and the AR/P graph; and an AR/P was used to help improve and enrich the model. The combination of AR/ P and CT is useful in studying the medicine problem related to the anatomical structure of upper respiratory tract.

Quantitative study of bone growth and remodeling adaptation model in rapid-growing rats / 中国组织工程研究

BACKGROUND: At present, bone remodeling biological model study usually applys finite element method combing with computer technique to simulate and predict bone quantity or bone structure. In this study the author integrate inversion method with animal experiment to establish a quantification bone remodeling biological model of in vivo bone tissue in real stress environment.OBJECTIVE: To set up a quantification biological model of bone growth and remodeling adaptation, which integrates animal experiments, parameter inversion identification of mathematical functions, and technique of computer simulation. DESIGN, TIME AND SETTING: The experiment was accomplished in Animal Experiment Center of Dalian Medical University in October 2002.MATERIALS: 60 female Sprague Dawley mice of 6-week old were used in this study. Challenger double-energy X ray bone density device was provided from DMS Company, France. Sensation l6 CT machine was provided from Germany Siemens Company.METHODS: 60 mice were randomly divided into two groups: i 5 animals were in normal control groups. 45 in experiment groups. By designing a new animal experiment, we investigate the effects of stress environments on bone growth and remodeling of rapid growing rats and gather the bone mineral density (BMD) of proximal femur in the same interval for the unknown parameters (B and K) inversion of bone growth and remodeling equation to create the femur three-dimension geometrical model based on CT images. MAIN OUTCOMING MEASURES: Body weight of animal, bone density and CT imagine of proximal femur. RESULTS: Body mass in the experiment group and control group was increased with the rat growing; BMD in the control group and overloading group was also increased with the rat growing; but BMD in the unloading group was decreased in the fifth week. Inversion and experimental data showed that parameter B was rapidly decreased as compared to time, and it was closed to zero in the 10th week. Parameter K was rapidly increased as compared to time. and it was gradually increased from the 5th to the 10th weeks, moreover, it was closed to the horizontal line after 10 weeks. This predicted that rapid growth was over, and bone reconstitution and absorption came into another balance cycle. CONCLUSION: The thought and method used in the model creating in.this paper provide clue and reference to establish human model of bone growth and remodeling.

Effect of removing turbinate on the airflow distribution in nasal cavity / 生物医学工程学杂志

The effect of variation of nasal structure on airflow distribution was investigated. Based on the CT images of the nose of a healthy female, a three-dimensional nasal model was developed. Two new nasal models were produced by removing part of inferior turbinate and part of middle turbinate in the left side of the original model. The numerical simulation and analysis for airflow field in the three nasal models was conducted by the finite element method. The simulation results from new models were compared with those from the original model. The airflow rate changed in the two sides of new nasal models. The airflow distribution and the pressure grades varied in the side of nasal model where part of inferior turbinate or part of middle turbinate was removed. The variation of nasal cavity structure will result in airflow redistribution in nasal cavity. The effect of removing turbinate on the airflow distribution in nasal cavity was described quantitatively.

The 3-D reconstruction of the nasal airway to model and analyze the airflow / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To investigate the nasal airflow-field in relation with the structure and function of the human nose.@*METHOD@#The 3-D finite-element mesh is developed from Spiral- CT imaging scans of the 25 healthy volunteers' noses. Given three preconditions, the nasal air-flow is described by the Navier-Stokes and continuity equations at the inspiratory flow rate of 10 min, then the whole airflow patterns are obtained for further analysis.@*RESULT@#(1) In 5 cases, the airflow passes mainly through the middle medial region in both sides in the nasal airway. In remaining 20 cases, the airflow passes mainly through the middle and ventral medial regions in one side in the nasal cavity while little air passes through middle medial regions in another the other side through which little air passes. (2) The differences of velocity in the nasal valve, middle and ventral medial regions of the nasal airway between mainly side and non maingnot-mainly side are of statistical significance, while those in the olfactory split, middle and inferior meatuses in both sides are of no statistical significance. (3) In the mainly side, the most rapid air speed occurred in the nasal valve , the second rapid velocity in the middle medial region and the third in the ventral medial regions, the slowest velocity in the olfactory split, middle and inferior meatuses. In notion- mainly side, the velocity in all regions is slow without statistical significance.@*CONCLUSION@#(1) At the inspiratory flow rate of 10 L/min, the middle and ventral medial regions act as the main airways in nasal cavity. (2) The airflow in nasal cavity can be directed effectively and reasonably by nasal valve, inferior turbinate, middle turbinate in turn, which may be consistent with the nasal cycle functionally.

Three dimensional reconstruction of the nasal cavity structure and numerical simulation of airflow / 生物医学工程学杂志

The nasal cavity structure of one patient was reconstructed by the method of surface rendering based on his CT images. In a respiratory period the change of air flux in the nasal cavity was supposed based on the tidal volume and the respiratory period gained by statistical method. The digital simulation and the analysis of the airflow in the nasal cavity was made by the FEA method and the result was compared with the data from literatures. The comparison indicates that the result is confident. From the result we can observe the airflow distribution quantitatively in the nasal cavity in the period of respiration.

Quantification study of bone adaptive model based on experiment of rapid-growing rats in different stress environment / 生物医学工程学杂志

Presented is a method to set up a quantification model of bone growing and remodeling adaptation, which integrates animal experiments, parameter identification of mathematical functions and technique of computer simulation. By designing a new animal experiment, we investigate the effects of growing and remodeling of the rat femurs in different stress environments, gather the bone mineral density (BMD) of proximal femur in the same interval for the unknown parameter (B and K) inversion of bone growing and remodeling equation and create the femur three-dimensional geometrical model based on CT images. The model in this paper can not only numerically measure the relation between outer stimulus and the femur BMD variation of rapid growing rats, but also predict the growth trend of rat femur under different stress environments in its whole lifecycle. The thought and method of creating the model in this paper can be used for reference to modeling human bone growth and remodeling.

A theoretical model study of open section effect on the mechanical properties of long bone / 生物医学工程学杂志

The mechanical model of femur mid-diaphysis with a rectangular open section in the exterior cortex was developed and a finite element method was adopted in calculating and analysing the changes of torsional stiffness and the stress distribution when the dimension of the open section altered. It showed that the open section with a length of 1 OD (femur mid-diaphysis diameter) had little influence on the femur torsional stiffness or stress distribution. The torsional stiffness decreased most dramatically as the length increased from 2 to 4 OD. Shear stress peaked at the center of the open section. This conclusion provides an important theoretical ground for the operative methods and the dimension control of an open section in clinical orthopaedics.

Biomechanical test study of rat femurs growing under different stress environment / 生物医学工程学杂志

By creating two kinds of stress environment in the same animal model, we performed a three-point bending test and a compressing test on the rat femurs growing under different stress conditions to characterize the effect of stress on bone mechanical properties. The right hindlimbs were subjected to sciatic nerve resection to become cripple and were used as unloading group; the left hindlimbs bore excess load and made up the overloading group; the normal rats were used as control group. The animals were encouraged to exercise for half an hour everyday in the morning, noon and evening. The experiment observation finished in four weeks. The biomechanical parameters of femur diaphyses were measured. The experiment results showed that stress environment may change several mechanical parameters of rat femurs. This study indicated that bone tissues can adapt to its stress environment by changing its mechanical properties. The experimental model in this article is practical and reliable.

Effect of low stress environment on bone density and geome-morphology of rat femur / 生物医学工程学杂志

6-week old rats were subjected to sciatic nerve resection and the right hindlimbs were then under a low stress environment. Bone mineral density (BMD) of different regions and geome-morphological parameters of femurs were measured. The results showed that the increase in the diameter, subperiosteal area and bone mineral density of femurs were suppressed obviously under low stress environment. But the sensitivity of BMD of different regions of the femur to the low stress environment was different. The suppression of the increase in femoral BMD was composed of an early impairment in the gain of BMD at the femoral metaphysis, which is rich in trabecular bone, and a sustained reduction in the gain of BMD at the femoral diaphysis, which is rich in cortical bone. The results of geome-morphology suggested that the early reduction in the increase of BMD at the metaphysis was due to an enhancement of bone resorption, whereas the suppression of gain in cortical bone mass and size is the result of a sustained reduction of periosteal bone formation.