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.
Biomedical Image Processing / Medical Image Processing
Emadoddin Fatemizadeh; Parisa Shooshtari
Volume 2, Issue 3 , June 2008, , Pages 191-201
Abstract
Nowadays due to the huge capacity and bandwidth essentials for medical images, communications and storage purposes, medical images compression is one of most important concepts in this area. Error free compression techniques have the weakness of low compression ratio. On the other hand, lossy techniques ...
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Nowadays due to the huge capacity and bandwidth essentials for medical images, communications and storage purposes, medical images compression is one of most important concepts in this area. Error free compression techniques have the weakness of low compression ratio. On the other hand, lossy techniques with high compression ratio result in low quality of the images. In recent years, some special compression schemes have been suggested by splitting the original image into two regions: Region of Interest (ROI) with lossless compression and the Region of Background (ROB) with lossy compression and a lower quality. In this paper, we proposed a novel selective compression approach to compress 3D brain MR images. For this purpose, an adaptive mesh for the first slice was designed and estimation of the gray levels of the next slices was performed through deformations of the mesh elements. After residual image determination, the error between the original image and the approximated image was transformed to the wavelet domain using a region-based discrete wavelet transform (RBDWT). Finally, the wavelet coefficients were coded by an object-based SPIHT coder.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Amin Zare; Reza Boostani; Mansour Zolghadr Jahromi
Volume 4, Issue 3 , June 2010, , Pages 195-208
Abstract
There is a growing interest to improve seizure prediction by online analyzing of electroencephalogram (EEG) signals in epileptic patients. Seizure attack is occurred infrequently and unpredictably; hence, automatic detection of seizure during long-term is highly recommended. In this paper a novel Feature ...
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There is a growing interest to improve seizure prediction by online analyzing of electroencephalogram (EEG) signals in epileptic patients. Seizure attack is occurred infrequently and unpredictably; hence, automatic detection of seizure during long-term is highly recommended. In this paper a novel Feature Reduction method namely AIS-RCA which adopted from the immunity system is proposed to improve the seizure detection rate. The automatic seizure detection can be performed in two successive stages: 1) The feature extraction/selection stage from EEG signals and 2) classifying the feature vectors by an efficient classifier. In this study, first, pseudo-Wigner-Ville distribution was applied to each window of the EEG signals and then the extracted features were transformed by AIS-RCA transform to represent the features in a more separable space. The AIS-RCA transformation matrix is estimated by using chunklets (a chunklet is defined as a subset of points that are known to be same). AIS-RCA using the proposed Artificial Immune System algorithm named Adaptive Distance-AIRS to discover the chunklets in the data space. Finally KNN classifier was applied to the transformed features to classify the seizure and non-seizure windows. The experimental results show that the proposed method yields epileptic detection accuracy rate up to 99.9% which is better than the results achieved by other types of features such as FFT, Wavelet transform, entropy and chaotic measures.
Elham Mollaei; Sasan Asiaei; Mahdi Moghimi; Ali Zadekafi
Volume 12, Issue 3 , November 2018, , Pages 199-210
Abstract
Microfluidic analytical/diagnostic tools, especially microfluidic paper-based analytical devices ( PADs) have attracted considerable attention due to their numerous advantages including their low operational costs, small analyte consumption, and limited required skills for use, and easy disposal/recycling. ...
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Microfluidic analytical/diagnostic tools, especially microfluidic paper-based analytical devices ( PADs) have attracted considerable attention due to their numerous advantages including their low operational costs, small analyte consumption, and limited required skills for use, and easy disposal/recycling. μPADs have been successful in detection of various diseases with no external deriving units. The aim of this study is to develop a micromixer for colorimetric detection of nitrite in saliva using Griess reaction and widening the limit of detection (LOD) by mixing improvement. Micromixers were fabricated using laser cut after a simple design. Five different geometries were examined and compared including straight, curved, zigzag, square wave and hexagonal, by numerical simulation and experimental tests for mixing part in micromixer. Simulations were performed in ANSYS CFX with homogeneous two-phase flow model in a porous media. As the result inclined hexagonal micromixer showed the best performance (in comparison with the straight one) exhibiting 44.24% of improvement which leads to a detection range and LOD of and , respectively. Considering the significant impact of micromixers in microfluidics, the quality of mixing and therefore the accuracy of the devices was improved by simple geometrical modifications.
Arghavan Farzadi; Mehran Solati Hashjin; Farhad Bakhshi; Alie Aminian
Volume 5, Issue 3 , June 2011, , Pages 206-213
Abstract
Using microwave irradiation in microwave-assisted synthesis method is a new approach employed to decrease synthesis time and to form more homogenous structures of biphasic calcium phosphate bioceramics. In this research, the microwave assisted synthesis and characterization of biphasic calcium phosphate ...
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Using microwave irradiation in microwave-assisted synthesis method is a new approach employed to decrease synthesis time and to form more homogenous structures of biphasic calcium phosphate bioceramics. In this research, the microwave assisted synthesis and characterization of biphasic calcium phosphate nanopowders have been studied. The phase transformation, chemical components, morphology and particle size were characterized by X-Ray Diffraction (XRD) analysis, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The results showed that the use of microwave led to improve crystallinity and the crystallite size increases from 16 nm to 27 nm. Also the amount of hydroxyapatite phase in biphasic calcium phosphate changed in the range of 5% to 17%. The prepared sample was put in Simulated Body Fluid (SBF).The pH of the solution was decreased in the present of beta-tricalcium phosphate showed its biodegradable behavior. Also the nucleation and growth of hydroxyapatite particles on TCP produced by microwave -assisted synthesis method changed to be rod like in SBF solution.
Biomedical Image Processing / Medical Image Processing
Nikta Jalayer; Majid Bagheri; Majid Pouladian
Volume 7, Issue 3 , June 2013, , Pages 209-217
Abstract
Recent developments in three-dimensional (3D) PET systems have enabled the spatial resolution to reach the 2- to 5-mm full-width-at-half-maximum (FWHM) range. With such improvements in spatial resolution, even small amounts of motion during PET imaging become a significant source of resolution degradation. ...
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Recent developments in three-dimensional (3D) PET systems have enabled the spatial resolution to reach the 2- to 5-mm full-width-at-half-maximum (FWHM) range. With such improvements in spatial resolution, even small amounts of motion during PET imaging become a significant source of resolution degradation. In other words, increased spending on new-generation scanners can be fully justified only when appropriate motion correction methods are considered, to achieve the true resolution of the scanner. Motion correction methods developed for single photon emission CT (SPECT) are not necessarily applicable to PET because they may rely on the time-dependence of projections in SPECT (due to a rotating head or heads), which is not the case in PET. Nevertheless, a number of other methods implemented in SPECT are equally applicable to PET. In this work has been broadly categorized into the review and discussion of advanced correction methods for the cases of unwanted patient motion, motion due to cardiac cycles, and motion due to respiratory cycles. After reviewing some current methods, the model is introduced which was developed with the help of NCAT phantom and Sim SET. Two phantoms were extracted, male and female, from NCAT to see the differences between the results with the changes in the anatomy of these two phantoms. Then PET images were produced using Sim SET for all the phantoms available (with respiratory motion and without respiratory motion and for respiratory cycles of 4, 5 and 6 seconds for both male and female phantoms). The new model is introduced which is designed based on the respiratory cycle 5 seconds, using wavelet transforms. This model can track and compensate motion due to respiration. The results show that for the first frame and the last one because of very smooth and slight motions the images with motion are not that different from the images without motion, so the proposed model is not responding better than the images with motion. However, for the rest of the frames the model provides better images compare to the images with motion. Comparing to other methods, this model not only provides a good estimation for motion but also it doesn’t include the errors caused by markers and monitoring systems.
Bioinformatics / Biomedical Informatics / Medical Informatics / Health Informatics
Hossein Bankikoshki; Seyed Ali Seyyedsalehi; Fatemeh Zare Mirakabad
Volume 11, Issue 3 , September 2017, , Pages 219-230
Abstract
The use of genomic nucleotide sequences as biochemical signals in machine learning methods is possible by converting these sequences into numerical codes. This conversion results in an unrealistic increase in the dimension of the data and encounters some data analysis operations such as visualization ...
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The use of genomic nucleotide sequences as biochemical signals in machine learning methods is possible by converting these sequences into numerical codes. This conversion results in an unrealistic increase in the dimension of the data and encounters some data analysis operations such as visualization and feature extraction with constraints. Therefore, one should use the dimensionality reduction technics in order to return the data to its real dimension. In this study, a deep autoencoder neural network has been used to reduce the dimension of binding site sequence data on the human genome. In order to determine whether the information of real data is preserved in compressed data, we perform a two-class classification using a support vector machine. The results show that information is almost entirely preserved in compression. Then, compressed data is used for visualization as well as feature selection by analysis of variance. The results show that the first, the tenth and eighth positions in the sequences are the most informative positions. While the majority of the previous works deal with gene expression data of microarrays and compare a few dimension reduction algorithms, this paper for the first time uses an autoencoder on nucleotide sequence data and provides a comprehensive comparison between the performance of the dimension reduction technics and machine learning algorithms.
Fluid-Structure Interaction in Biological Media / FSI
Hoda Mastari Farahani; Nasser Fatouraee
Volume 10, Issue 3 , October 2016, , Pages 223-230
Abstract
Syrinx growth in Syringomyelia desease causes progressive neurological disorders. Thus, the examination of effective factors in syrinx development is so important for controlling this desease. One of clinical assumptions related to the reason of syrinx development, considers the propagation of pressure ...
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Syrinx growth in Syringomyelia desease causes progressive neurological disorders. Thus, the examination of effective factors in syrinx development is so important for controlling this desease. One of clinical assumptions related to the reason of syrinx development, considers the propagation of pressure wave shock in subarachnoid-space fluid as the main reason for fluid motion in syrinx and syrinx development and increasing damage to spinal cord. Modeling and analysis have been performed to test the theory in this research using finite element method. So a 3d model was created including syrinx, spinal cord, cerebrospinal-fluid in subarachnoid-space, dura mater and stenosis. Pressure puls stimulation was applied to the superior surface of the subarachnoid-space fluid model simulating arterial puls of skull. Cerebrospinal-fluid has been assumed as a Newtonian fluid with laminar flow. The solid phase has been considered to be linear elastic. The fluid-solid interface was analized using ADINA software and fluid flow characteristics were extracted including velocity and pressure field as well as tissue stresses. Results show that pressure wave propagation in subarachnoid-space fluid causes the induction of motion in syrinx fluid, and stress concentration is created in spinal tissue due to the fluid cessation in syrinx and increasing local pressure, however these stress values are lower than spinal tissue strength and pressure wave propagation in this situation cannot be the main reason of syrinx development.
Mahla Dehtaghi Zadeh; Farid Saberi-Movahed; Mahdi Eftekhari
Volume 13, Issue 3 , October 2019, , Pages 223-234
Abstract
DNA micro-array datasets play crucial role in machine learning and recognition of various kinds of cancer structures. Micro-array datasets are typically characterized by the high number of features and the small number of samples. Such problems may result in overfitting and low prediction accuracy of ...
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DNA micro-array datasets play crucial role in machine learning and recognition of various kinds of cancer structures. Micro-array datasets are typically characterized by the high number of features and the small number of samples. Such problems may result in overfitting and low prediction accuracy of classifiers due to the irrelevant features, and therefore, they are considered as a challenging task in machine learning. The direct way to deal with such challenges is dimensionality reduction of data. In this regard, feature selection method acts as an effective solution for dimensinality reduction and increasing efficiency of learning algorithms. In this paper, by using the concept of “the basis for the DNA micro-array datasets”, a new feature selection method is introduced. To be more specific, rather than utilizing the entire micro-array dataset for tackling the problem of feature selection, a basis that is a muchmore smaller subset of the micro-array dataset is used. This method is based on subspace learning and matrix factorization. Finally, by making use of the DNA micro-array datasets, the effectiveness of the proposed method is evaluated, and the obtained results are compared with some state-of-the-art supervised feature selection methods.
Targeted Drug Delivery / Smart Drug Delivery / Drug Targeting
Vahid Khandan; Bahar Firoozabadi; Mohammad Saeid Saeidi
Volume 8, Issue 3 , September 2014, , Pages 229-239
Abstract
A hallmark of Alzheimer disease (the most common type of dementia in the elderly) is the aggregation and deposition of toxic species ranging from small soluble oligomers to insoluble fibril plaques of Amyloid-Beta protein originates from the cleavage of APP by Beta and Gama Secretase (Amyloid Hypothesis). ...
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A hallmark of Alzheimer disease (the most common type of dementia in the elderly) is the aggregation and deposition of toxic species ranging from small soluble oligomers to insoluble fibril plaques of Amyloid-Beta protein originates from the cleavage of APP by Beta and Gama Secretase (Amyloid Hypothesis). An attractive therapeutic approach to treat AD is to identify small ligands capable of binding to A-Beta monomers and reverse its amyloidosis process. Here, a peptide drug having the sequence of GLMVG which has been derived from the C-terminal of A-Beta was used as breaker for a monomer of Beta sheet rich structure. The combination of Docking and Molecular Dynamics methods were used for simulation of drug-receptor interaction. This simulation implied that pentapeptide altered secondary structure of A-Beta monomer and declined its stability. This study proved that pentapeptide is capable to reverse Beta-sheet formation and can be considered as an AD drug in other preclinical studies.
Brain Computer Interface / BCI / Neural Control Int. / NCI / Mind Machine Int. / MMI / Direct Neural Int. / DNI / Brain Machine Int. / BMI
Ali Maleki; Maedeh Azadimoghadam
Volume 16, Issue 3 , December 2022, , Pages 229-240
Abstract
A significant challenge in moving SSVEP-based BCIs from the laboratory into real-life applications is that the user may suffer from fatigue. Prolonged execution of commands in a BCI system can cause mental fatigue and, as a result, create dissatisfaction in the user and reduce the system's efficiency. ...
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A significant challenge in moving SSVEP-based BCIs from the laboratory into real-life applications is that the user may suffer from fatigue. Prolonged execution of commands in a BCI system can cause mental fatigue and, as a result, create dissatisfaction in the user and reduce the system's efficiency. The first step to studying and ultimately reducing the destructive effects of fatigue is to identify the level of fatigue. Although frequency indices have been used for fatigue evaluation, the results of previous research in this field are inconsistent. Therefore, there is no detailed and comprehensive investigation of how fatigue affects frequency indices. In this paper, the evaluation of frequency-domain fatigue indicators has been done accurately and comprehensively. For this purpose, nine visual stimuli with different flickering frequencies were displayed to the subject, and they were asked to pay attention to the target cue. The visual stimulation was presented continuously, without rest to ensure that the fatigue occurs at the end of the test. Mean amplitude of theta, alpha, and beta bands, and 4-30Hz frequency band segments with 1Hz, 2Hz, and 4Hz steps were evaluated as fatigue indices. The results show that the mean amplitude of the frequency band of 8-9 Hz is more suitable for fatigue evaluation. This index has the most changes with fatigue in a state of wakeful relaxation of the subject and the mental effort to maintain the level of alertness in the fatigue state.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Mahdi Zolfagharzadeh Kermani; Mohammad Ali Khalilzadeh; Majid Ghoshuni; Peyman Hashemian
Volume 9, Issue 3 , December 2015, , Pages 243-251
Abstract
Evaluation and measurement of parameters associated with methamphetamine craving can be a valuable tool in the management and intervention programs related to methamphetamine use and dependence. We believe that quantitative electroencephalography (EEG) have brought about a revolution in identification ...
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Evaluation and measurement of parameters associated with methamphetamine craving can be a valuable tool in the management and intervention programs related to methamphetamine use and dependence. We believe that quantitative electroencephalography (EEG) have brought about a revolution in identification the neurologic infrastructure of craving processing. This study has been conducted aimed to design and develop a new method to measure baseline craving in methamphetamine-dependent patients using EEG signals in neurofeedback therapy for separation of the three modes of low, medium, and high craving. For this purpose, 10 methamphetamine abusers were selected by available method in terms of age, sex and IQ. All patients received 10 sessions of neurofeedback therapy with alpha-theta protocol. During the period of treatment with neurofeedback, before and 60 minutes after each training session, at rest state, on Pz, for 2 minutes and 10 seconds EEG was recorded. To labeling EEG signals we have used Desire for Drug Questionnaire (DDQ). After collecting the required data from signals, time, frequency and nonlinear features were extracted. Then by calculating the linear correlation coefficient of the two variables and variance analysis on three levels optimized and effective features were selected. Finally, using fuzzy classifier, those features were separated into three classes of low, medium and high craving. According to the results, separation accuracy of EEG signals in three classes by K-fold Cross-Validation (KCV)method was 96.67% and test data was 75.15%. This study showed in addition to estimating baseline craving in methamphetamine abusers by quantifying EEG we can optimize the number of training sessions for participants.
Biomechanics of Bone / Bone Biomechanics
Mina Gharenazifam; Ehsan Arbabi
Volume 6, Issue 4 , June 2012, , Pages 267-278
Abstract
One of the main causes of early osteoarthritis of the hip is Femoroacetabular Impingement (FAI). When the femoral head loses its spherical shape at head-neck junction, a special type of impingement, called Cam impingement, occurs. Alpha angle can be used as a geometric parameter for evaluating this kind ...
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One of the main causes of early osteoarthritis of the hip is Femoroacetabular Impingement (FAI). When the femoral head loses its spherical shape at head-neck junction, a special type of impingement, called Cam impingement, occurs. Alpha angle can be used as a geometric parameter for evaluating this kind of anatomic deformity. In this article we propose a fully automatic strategy for estimating alpha angle by analyzing 3D data. In the proposed strategy a radial plane around the femoral head-neck axis is rotated in order to provide alpha angles in different orientations. For evaluating the proposed method, the alpha angle of twelve 3D femur models of female subjects, reconstructed from magnetic resonance images (including both right and left femur), have been estimated. The mean and standard deviation of these estimated alpha angles have been found to be in good agreement with the expected values for alpha angle in healthy human. In addition, the effect of the data resolution on the provided results has been evaluated in terms of accuracy and speed, by using four different resolutions of 3D meshes. The results indicate that using 64 times lower data resolution can increase the computational speed up to about 8 times and add an average error of about 2° to the estimated alpha angles.
Tissue Engineering
Farhad Farmanzad; Siamak Najarian; Mohammad Reza Eslami; Amir Saeed Seddighi
Volume 1, Issue 4 , June 2007, , Pages 281-288
Abstract
Two different types of computer modeling, i.e., the elastic and hyperelastic plane strain models were employed and compared with each other. Using finite element analysis, we determined a suitable model for describing the biomechanical behavior of the brain, especially the deformation and displacement ...
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Two different types of computer modeling, i.e., the elastic and hyperelastic plane strain models were employed and compared with each other. Using finite element analysis, we determined a suitable model for describing the biomechanical behavior of the brain, especially the deformation and displacement of the brain ventricles. The CT-Scan of an epidural hematoma patient was modeled using both approaches. Then, by varying the mechanical parameters of the tissue (i.e., C10, C01, E, and v) and the internal ventricular pressure, the displacement rate of the corresponding points in the ventricles was simulated. Finally, the results of the simulation were compared with those of the actual ventricles, and then, the data set with the least amount of error was identified. For various types of loadings and with different pressure gradients, the results of the simulation show that if the effect of an increase in the internal pressure of the ventricles is neglected, it will lead to unrealistic results. Particularly, in unidirectional strain loading with a pressure gradient of zero (AP= 0), the walls of the ventricle adjacent to the hematoma will collapse completely. The best results were obtained for the elastic model where ΔP = 9.4 mmHg (1.25 kPa) and for the hyperelastic model where ΔP = 7.5 mmHg (1.00 kPa). These findings are consistent with the clinical conditions of the patient. In the plane strain biomechanical modeling, for unidirectional strain loading (conditions which are similar to the application of navigation systems in surgeries), neglecting the geometry and the variation of the internal pressure of the ventricles will not lead to acceptable results. Taking into account the abovementioned parameters in describing the mechanical behavior of the brain (for epidural hematoma lesions), the elastic model (88.7% average relative accuracy) brings about better results compared with those of the hyperclastic model (86.9% average relative accuracy).
Spinal Biomechanics
Mehran Kasra
Volume 3, Issue 4 , June 2009, , Pages 285-290
Abstract
The influence of compression on intervertebral disc cells has been examined in a number of previous studies. However, in most of these studies hydrostatic pressure was used at low levels, and few studies reported the effects of high pressures within a large range of frequencies on intervertebral disc ...
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The influence of compression on intervertebral disc cells has been examined in a number of previous studies. However, in most of these studies hydrostatic pressure was used at low levels, and few studies reported the effects of high pressures within a large range of frequencies on intervertebral disc cells response. The aim of the study was to test the hypothesis that frequency dependent hydrostatic pressure stimulates collagen synthesis in the intervertebral disc cells to a certain level. Hydrostatic pressure was applied to the intervertebral disc cells in a monolayer culture using a custom-made piston chamber pressure vessel. Briefly, cells were harvested from the intervertebral discs in the lumbar region of a pig, plated, and grown to confluence in culture flasks; they were then trypsinized and re-attached to 35mm culture dishes. With cyclic, hydrostatic loading, the cells were exposed to varied pressures and frequencies for 20 minutes a day for 3 and 7 days (the controls received no loading). The intracellular collagen was labeled with 3[H]-proline after loading on days 2 and 6. Following treatments on days 3 and 7, both the media and cells were frozen separately. Scintillation counting determined the amount of collagen incorporated in the cells and released into the media; these values were normalized by DNA. In this culture system, the results indicated significant differences (P<0.05) in cell response at different loading conditions. Compared to the control group there was a significant decrease in released collagen at high loading amplitude and low frequency (5MPa, 1Hz) which increased significantly at high loading frequencies (5MPa, 15Hz) indicating anabolic response at high pressures which became catabolic at high frequencies.
Behrouz Jafarzadeh; Hanieh Niroomand-Oscuii; Farzan Ghalichi
Volume 12, Issue 4 , January 2019, , Pages 287-297
Abstract
Mock circulation systems are necessary for in vitro experiments and development of the ventricular assist devices, heart valves, total artificial hearts, artificial lungs, vascular grafts and intra-aortic balloon pumps. Tissue engineering of heart valves and other preliminary studies on the cardiovascular ...
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Mock circulation systems are necessary for in vitro experiments and development of the ventricular assist devices, heart valves, total artificial hearts, artificial lungs, vascular grafts and intra-aortic balloon pumps. Tissue engineering of heart valves and other preliminary studies on the cardiovascular system can also achieve with mock circulation systems. One of the major parts of these systems is generating of pulsatile flows like heart. In this study a mock circulation system with ability of physiological pressure and flow simulation in both healthy and diseases heart has been designed and manufactured. This setup can produce pressure and flow pulse by using a positive displacement pump with programing of movement pattern of stepper motor. This pump was manufactured after designing by Solid-works software for using in the mock circulation system. For testing this setup, several experiments with different values of peripheral resistance and arterial compliance and changing the pattern of the stepper motor have been performed. The results show modifying the pattern of the stepper motor from uniform speed to variable speed in one cycle (360 degree), as well as changing in arterial compliance and peripheral resistance, can produce waveform of physiological pressure and flow. The results confirm the reliable performance of this system in simulating physiological conditions. The designed system has the software capability to generate different waveforms.
Biomedical Image Processing / Medical Image Processing
Gelareh Valizadeh; Farshid Babapour Mofrad; Ahmad Shalbaf
Volume 14, Issue 4 , February 2021, , Pages 291-306
Abstract
Statistical Shape Modeling is widely used in many applications of cardiac images. Many efforts have been done to generate optimized Statistical Shape Models (SSMs). In this paper, we evaluated three different 3D endocardial models constructed using different alignment procedures. From 20 healthy CMR ...
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Statistical Shape Modeling is widely used in many applications of cardiac images. Many efforts have been done to generate optimized Statistical Shape Models (SSMs). In this paper, we evaluated three different 3D endocardial models constructed using different alignment procedures. From 20 healthy CMR datasets, three different endocardial models are generated by varying the surface alignment methods means based on the Center of the Apex (CoA), the Center of Mass (CoM), and the Center of the Basal (CoB) of the endocardium. Then Principle Component Analysis (PCA) is applied to show the maximum variation of the SSMs. The constructed statistical models are compared by measuring the compactness, generalization ability, and specificity. Besides, the performance of each model in the 3D endocardial segmentation application using the Active Shape Model (ASM) technique is evaluated by the Hausdorff Distance (HD) criterion. The results indicate that the CoB-based model is less compact than the CoA-based model but more compact than the CoM-based model. Although for a constant number of modes the reconstruction error is approximately the same for all models, surface alignment based on CoB leads to generate a more specific model than the others. The resulted HDs show that the CoB alignment strategy produces the ASM which has the best performance in 3D endocardial segmentation among the other models. The computed results from the quantitative analysis demonstrate that varying alignment strategies affect the quality of the constructed SSM. It is obvious that the specificity and segmentation accuracy of the proposed CoB-based model outperforms the classical CoM-based approach.
Zahra Amini; Vahid Abootalebi; Mohammad Taghi Sadeghi
Volume 4, Issue 4 , June 2010, , Pages 293-306
Abstract
The aim of this paper is to design a pattern recognition based system to detect P300 component in multi-channel electroencephalogram (EEG) trials. This system has two main blocks, feature extraction and classification. In feature extraction block, in addition to conventional features namely morphological, ...
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The aim of this paper is to design a pattern recognition based system to detect P300 component in multi-channel electroencephalogram (EEG) trials. This system has two main blocks, feature extraction and classification. In feature extraction block, in addition to conventional features namely morphological, frequency and wavelet features, some new features included intelligent segmentation, common spatial pattern (CSP) and combined features (CSP + Segmentation) have also been used. Three criteria were used for evaluation and selection of a feature set by choosing a subset of the original features that contains most of essential information. Firstly, a statistical analysis has been applied for evaluating the fitness of each feature in discriminating between target and non target signals. Secondly, each of these six groups of features was evaluated by a Linear Discriminant Analysis (LDA) classifier. Furthermore by using Stepwise Linear Discriminant Analysis (SWLDA), the best set of features was selected. Among these six feature vectors, intelligent segmentation was seen to be most efficient in classification of these signals. In classification phase, two linear classifiers -LDA and SWLDA- were used. The algorithm was described here has tested with dataset II from the BCI competition 2005. In this research, the best result for P300 detection is 97.05% .This result have proven to be more accurate than the results of previous works carried out in this filed.
Cardiovascular Biomechanics
Mohammad Shafigh; Nasser Fatouraee; Amir Saeed Seddighi
Volume 5, Issue 4 , June 2011, , Pages 297-304
Abstract
Understanding of mechanical properties of healthy brain arteries is a key element in the development of clinical diagnosis and prevention.For this reason we make biaxial measurements to have appropriate parameters for the underlying material models. To acquire these properties, eight samples were obtained ...
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Understanding of mechanical properties of healthy brain arteries is a key element in the development of clinical diagnosis and prevention.For this reason we make biaxial measurements to have appropriate parameters for the underlying material models. To acquire these properties, eight samples were obtained from middle cerebral arteries of human cadavers, whose death were not due to injuries or diseases of cerebral vessels, and tested within twelve hours after resection. The changes of force and deformation until the vessel rupture were recorded. Thereafter, the stress-strain curves were plotted and fitted with a hyperelastic five-parameter Fung model parameters, according to the best fit, were determined. It was found that the arteries were remarkably stiffer in circumferential than in axial direction. It was also found that the use of multi-parameter hyperelastic constitutive models is applicable for mathematical description of behavior of cerebral vessel tissue. The reported material properties can be a proper reference for numerical simulation of cerebral arteries of healthy or diseased intracranial arteries.
Mehran Baboli; Seyed Ali Ghorashi; Namdar Saniei; Alireza Ahmadian
Volume 2, Issue 4 , June 2008, , Pages 297-303
Abstract
Ultra Wide Band (UWB) signals are widely used in medical applications. In this paper, we developed a novel non-contact monitoring system to measure the heart rates of patients using UWB signals. The work is performed in two stages. First, a simulated UWB system including a model for human body is developed, ...
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Ultra Wide Band (UWB) signals are widely used in medical applications. In this paper, we developed a novel non-contact monitoring system to measure the heart rates of patients using UWB signals. The work is performed in two stages. First, a simulated UWB system including a model for human body is developed, where heart is simulated using simple layered model, and then its rate is detected. In second stage, real experiments are carried out on human body using UWB radar with 3.2 GHz bandwidth, and a new practical wavelet based algorithm is proposed to detect heart rate. The proposed algorithm has a high precision (98%) and accuracy (92%) and appears to be promising for future monitoring systems.
Biomechanics / Biomechanical Engineering
Nima Sarrafzadeh Ghadimi; Farzan Ghalichi; Hanieh Niroomand-Oscuii; Nasser Fatouraee
Volume 15, Issue 4 , March 2022, , Pages 299-312
Abstract
Considering the common diseases that occur in the heart valves, it is possible that these valves can be replaced with artificial valves. This article examines different types of polymeric valves for the possibility of replacement in the human body. Different models are compared and the optimal valve ...
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Considering the common diseases that occur in the heart valves, it is possible that these valves can be replaced with artificial valves. This article examines different types of polymeric valves for the possibility of replacement in the human body. Different models are compared and the optimal valve is presented. For complete information, refer to the text of the article.
Biomedical Image Processing / Medical Image Processing
Parisa Gifani; Hamid Behnam; Maryam Shojaee Fard
Volume 10, Issue 4 , January 2017, , Pages 303-313
Abstract
In this paper, we introduce a novel framework for illustrating the cardiac movements in echocardiogarphic images by utilizing temporal information and sparse representation. For the proposed method, we first derived temporal information by extracting intensity variation time curves (IVTC) assessed for ...
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In this paper, we introduce a novel framework for illustrating the cardiac movements in echocardiogarphic images by utilizing temporal information and sparse representation. For the proposed method, we first derived temporal information by extracting intensity variation time curves (IVTC) assessed for each pixel. Then an over complete dictionary based on prior knowledge of the temporal signals and a set of pre-specified known functions was designed. The IVTCs can then be described as linear combinations of a few prototype atoms in the dictionary. We used the Bayesian Compressive Sensing (BCS) sparse recovery algorithm to find the sparse coefficients of the signals. By decomposing the IVTCs to different families and extracting proper features based on the sparse information, we attain the color coded images which illustrates the general movements of cardiac segments. The database consists of 21 echocardiography sequence of normal and abnormal volunteers in short axes and 4 chamber views. The results show the great achievement in global wall motion estimations.
Biological Computer Modeling / Biological Computer Simulation
Abbas Gholami; Amir Shamloo
Volume 11, Issue 4 , February 2018, , Pages 303-311
Abstract
PASylation is a new and effective way to increase the half-life of pharmaceutical proteins. This method is an alternative of PEGylaion and uses the natural polymers of Proline, Alanine, and Serine (PAS) amino acids in its structure. In this paper, we have studied the pharmacokinetic properties of PASylated ...
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PASylation is a new and effective way to increase the half-life of pharmaceutical proteins. This method is an alternative of PEGylaion and uses the natural polymers of Proline, Alanine, and Serine (PAS) amino acids in its structure. In this paper, we have studied the pharmacokinetic properties of PASylated Granulocyte-colony stimulating factor (G-CSF) using Molecular Dynamics (MD) simulation for three different PAS strings length 210, 420 and 630. We studied several important mechanical quantities involving in enhancing half-life time of the conjugated protein like root-mean-square distance (RMSD), hydrodynamic volume, protein total energy and its hydrophilicity and we found out volume expansion, increase in hydrophilicity amount and coil structure in PASylation are main mechanical properties influencing half-life time. We also found out that RMSD will be modified by PASylation while energy level shows erratic behavior examining the mentioned residues properties, we have also offered a modified sequence for PAS string according to the importance of different parameters in PAS string’s function.
Dariush Nazarinasab; Alireza Mirbagheri; Farzam Farahmand; Elnaz Afshari
Volume 7, Issue 4 , June 2013, , Pages 311-319
Abstract
During laparoscopy surgery, the surgeon cannot touch the tissues directly by his/her hand. As a result, he is not able to use tactile sensing for evaluating the tissues’ mechanical behavior and diagnosing their normal/pathological conditions. Furthermore in vivo biomechanical characteristics of ...
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During laparoscopy surgery, the surgeon cannot touch the tissues directly by his/her hand. As a result, he is not able to use tactile sensing for evaluating the tissues’ mechanical behavior and diagnosing their normal/pathological conditions. Furthermore in vivo biomechanical characteristics of Intraabdominal soft tissues are among the main data required for surgery simulator softwares. The purpose of this research was to design and analyze a robotic surgical instrument which could grasp and compress the intra-abdominal large soft tissues and provide their force-displacement characteristics. The designed device is analogous to a robotic hand with two fingers, which are opened and closed using a parallelogram mechanism. A combined mechanism, including two connected sliding links and a compensatory cam, are used to prevent the fingers horizontal motion and keep the contact area fixed. The results of the kinematics analysis indicate the efficacy of the designed mechanism to provide pure vertical motion in fingers, parallel to each other. Also, the results of dynamic analysis indicate that, after dimensional optimization, the maximum force required at the actuator is 65 N, to apply a 10 N compressive force to the tissue at the middle of grasping range.
Reza Sahebi Kuzeh Kanan; Hanieh Niroomand-Oscuii; Kohyar Yazdanpanah-Ardakani
Volume 13, Issue 4 , December 2019, , Pages 315-326
Abstract
Nowadays, patients crowd suffering from heart disease are increasing along with the development of technology and mechanized life. On the other hand, donor hearts ready for transplantation is limited in the world. Therefore, exploiting blood pumps is a suitable alternative for helping the patient during ...
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Nowadays, patients crowd suffering from heart disease are increasing along with the development of technology and mechanized life. On the other hand, donor hearts ready for transplantation is limited in the world. Therefore, exploiting blood pumps is a suitable alternative for helping the patient during the waiting time and even until the end of life. The blood pumps should be able to satisfy the biological needs, including proper output pressure and flow rate, in an acceptable margin of safety in terms of blood injuries. Reduction of pump size, blood exposure time and blood damages such as hemolysis are mentioned as the important challenges in the design of blood pumps. 30% of the patients who are using a left ventricle blood pump, required right ventricle blood pump due to right ventricle failure. Fulfilling the physiological requirement of right ventricle a RVAD must generate pressure in the range of 15-25 mmHg and flow rate equal to 5 L/min. generation of pressure over 25 mmHg will lead to pulmonary hypertension and its consequent problems. In this research, a centrifugal blood pump is designed for the right ventricle with an emphasis on impeller geometry. This pump is simulated for rotational speeds of 1500, 2000 rpm and flow rates of 4-6 L/min by using the computational fluid dynamics. The designed pump produces a flow rate of 5 L/min at 1500 rpm and a pressure of 23 mmHg. The amount of the hemolysis index calculated by the Lagrangian method is 0.00413.
