Cardiovascular Biomechanics
Mosayeb Mobasheri; Manije Mokhtari Dizaji; Faride Roshanali
Volume 10, Issue 1 , May 2016, , Pages 11-23
Abstract
Heart torsion is one of the biomechanical parameters that are sensitive to changes in both regional and global left ventricular (LV) function. In this study, angle of myocardium’s trajectory in three dimensions (Ф) was estimated by simultaneous use of two dimensional long apical and short ...
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Heart torsion is one of the biomechanical parameters that are sensitive to changes in both regional and global left ventricular (LV) function. In this study, angle of myocardium’s trajectory in three dimensions (Ф) was estimated by simultaneous use of two dimensional long apical and short axis views of LV septum sequential images. Then correlation of 3D angle and 2D rotation angle from long (χ) and short (θ) axis views respectively was estimated and compared at three levels of base, mid and apex of interventricular septum wall. Sequential two dimensional echocardiography images of long and short axis views with minimum temporal resolution 14 ms of 19 healthy men was recorded and analyzed. Interventricular septum wall motion at three levels of base, mid and apex were estimated using sequential images processing of echocardiography in long and short axis views with block matching algorithm throughout three cardiac cycles. Then correlation of 2D angle of rotation from long (χ) and short (θ) axis views was analyzed with three dimentional angular of myocardium’s trajectory (Ф) at three levels of base, mid and apex of interventricular septum wall. Ф, θ and χ angles at base level 16.33±3.01, 10.61±3.38 and 15.11±3.30 degrees, mid level 22.77±4.95, 7.78±2.96 and 16.72±2.66 degrees and apex level of interventricular septum wall 14.60±5.81, 10.37±5.48 and 8.79±3.32 degrees were extracted respectively. Regard to sensitivity of 3D angle to variation of motion in each of three dimensions, it is suggested for examination of biomechanical behavior myocardium in different pathologic conditions.
Bioheat Transfer
Mehdi Maerefat; Manije Mokhtari Dizaji; Zahra Haddad Soleimani
Volume 3, Issue 3 , June 2009, , Pages 189-197
Abstract
In this paper a comprehensive mathematical model for thermal analysis of liver tissue in thermotherapy of liver cancer by laser is presented. In the present model the diffusion approximation analytical method for radiative heat transfer modeling of heat transfer process in the tissue is used for the ...
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In this paper a comprehensive mathematical model for thermal analysis of liver tissue in thermotherapy of liver cancer by laser is presented. In the present model the diffusion approximation analytical method for radiative heat transfer modeling of heat transfer process in the tissue is used for the first time. Heat transfer modeling in the biological tissue is carried out using Penes model taking into account the influence of thermal and blood perfusion coefficient fluctuations due to temperature changes as well as the effect of lipid melting on temperature distribution through enthalpy method is taken into account. In the present study the tumor is considered as a sphere with thermo-physical properties different with those of healthy tissue. Finally, the obtained non-linear equations are solved using the numerical finite volume method. Temperature distribution at several instants during the thermotherapy is calculated. The comparison of the calculated results with those of experimental results indicate a good agreement between the results. Furthermore, the effects of different parameters such as laser specifications and optic coefficient changes (through proper photopherin injection) on laser-affected area are studied using the present analytical method. These results can help the specialists in order to come upon a safe LITT method for destruction of cancerous tissues without harming the healthy ones.
Cardiovascular Biomechanics
Mehdi Maerefat; Asghar Khoushkar Shalmani; Manije Mokhtari Dizaji
Volume 1, Issue 2 , June 2007, , Pages 95-104
Abstract
Modeling of blood flow and arterial wall in large arteries such as carotid artery, using ultrasonic measurements, allows non-invasive evaluation of clinically interesting homodynamic variables. In this study, a nonlinear mathematical model for the pulsatile arterial flow is proposed using the approximation ...
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Modeling of blood flow and arterial wall in large arteries such as carotid artery, using ultrasonic measurements, allows non-invasive evaluation of clinically interesting homodynamic variables. In this study, a nonlinear mathematical model for the pulsatile arterial flow is proposed using the approximation of “local flow” theory. The blood velocity profile, the pressure gradient and the elastic modulus can be calculated using the model by measuring instantaneous radius and center-line blood velocity. An original mathematical model of pressure gradient in a tapered and elastic tube, using center-line blood velocity, is presented. A Newtonian incompressible Navier-Stokes solver coupled with elastic or visco-elastic arterial wall model is developed to solve the equations of model. The results of modeling and simulation indicate that the approach can estimate the elastic modulus of arterial wall from ultrasonic data. There is a good agreement between the computed arterial wall elasticity and the measured one. The method presented is relatively simple to implement clinically and can be taken as a new diagnostic tool for detecting local vascular change.
