Research and Development Center for Bioengineering Bio

Kragujevac, Serbia

Research and Development Center for Bioengineering Bio

Kragujevac, Serbia
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Bosnic Z.,University of Ljubljana | Vracar P.,University of Ljubljana | Radovi M.D.,Research and Development Center for Bioengineering Bio | Devedzic G.,University of Zagreb | And 2 more authors.
IEEE Transactions on Information Technology in Biomedicine | Year: 2012

One of the most common causes of human death is stroke, which can be caused by carotid bifurcation stenosis. In our work, we aim at proposing a prototype of a medical expert system that could significantly aid medical experts to detect hemodynamic abnormalities (increased artery wall shear stress). Based on the acquired simulated data, we apply several methodologies for1) predicting magnitudes and locations of maximum wall shear stress in the artery, 2) estimating reliability of computed predictions, and 3) providing user-friendly explanation of the models decision. The obtained results indicate that the evaluated methodologies can provide a useful tool for the given problem domain. © 2012 IEEE.


Radovic M.D.,Research and Development Center for Bioengineering Bio | Filipovic N.D.,University of Zagreb | Bosnic Z.,University of Ljubljana | Vracar P.,University of Ljubljana | Kononenko I.,University of Ljubljana
Proceedings of the IEEE/EMBS Region 8 International Conference on Information Technology Applications in Biomedicine, ITAB | Year: 2010

Arterial geometry variability is present both within and across individuals. To analyze the influence of geometric parameters on maximal wall shear stress (MWSS) in the human carotid artery bifurcation, the computer simulations were run to generate the data pertaining to this phenomenon. In our work we evaluate various prediction models for modeling relationship between geometric parameters of the carotid bifurcation and the MWSS. The results revealed the highest potential of using the neural network model for this prediction task. The achieved results and generated explanations of the prediction model represent progress in assessment of stroke risk for a given patient's geometry in real time. © 2010 IEEE.


Radovic M.,Research and Development Center for Bioengineering Bio | Djokovic M.,University of Kragujevac | Peulic A.,University of Kragujevac | Filipovic N.,Research and Development Center for Bioengineering Bio | Filipovic N.,University of Zagreb
13th IEEE International Conference on BioInformatics and BioEngineering, IEEE BIBE 2013 | Year: 2013

One of the leading causes of cancer death among women is breast cancer. In our work we aim at proposing a prototype of a medical expert system (based on data mining techniques) that could significantly aid medical experts to detect breast cancer. This paper presents the CAD (computer aided diagnosis) system for the detection of normal and abnormal pattern in the breast. The proposed system consists of four major steps: the image preprocessing, the feature extraction, the feature selection and the classification process that classifies mammogram into normal (without tumor) and abnormal (with tumor) pattern. After removing noise from mammogram using the Discrete Wavelet Transformation (DWT), first is selected the region of interest (ROI). By identifying the boundary of the breast, it is possible to remove any artifact present outside the breast area, such as patient markings. Then, a total of 20 GLCM features are extracted from the ROI, which were used as inputs for classification algorithms. In order to compare the classification results, we used seven different classifiers. Normal breast images and breast image with masses (total 322 images) used as input images in this study are taken from the mini-MIAS database. © 2013 IEEE.


Krsmanovic D.,University of Zagreb | Koncar I.,Serbian Clinical Center | Petrovic D.,Research and Development Center for Bioengineering Bio | Milasinovic D.,Research and Development Center for Bioengineering Bio | And 2 more authors.
10th International Workshop on Biomedical Engineering, BioEng 2011 | Year: 2011

Migration of the forces in patient specific aorta stent grafts is very important phenomena. Several complications remain to be fully resolved and hemodynamics drag forces seem to be one of the most important factor. The objective of this work was to investigate maximal drag force in endoluminal stent-graft in simplified and patient specific computer model. A simple curved tube with minimal and maximal diameter of 24 and 46 mm was used to simulate extreme cases of 90° bent stent for drag force calculation. A patient specific computer model was reconstructed from dual 64 multislice CT (MSCT) device. Finite element method with steady and transient laminar flow solver is implemented. Pressure, shear stress and velocity distributions for simplified curved tube and patient specific case were presented. Also a total drag force was calculated for steady and full transient case. The maximum migration forces is 8.15N for 0.024m graft bent under 90°, and 29.88 N for 0.046m graft bent under 90°. A real case patient shows maximal drag force of 12.6 N at peak systole. We found that maximal migration forces for the worst scenario could be as high as 29.88 N in certain situations. However, this is by far the worst case scenario where the entire unsupported length of the largest available size of thoracic aortic aneurysm (TAA) graft makes up the 90 bend. Computer simulation may predict for each specific patient the drag force magnitude which may be a clear benefit for patient follow-up study. © 2011 IEEE.


Milos R.,Research and Development Center for Bioengineering Bio | Dejan P.,Research and Development Center for Bioengineering Bio | Nenad F.,Research and Development Center for Bioengineering Bio | Nenad F.,University of Zagreb
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS | Year: 2011

Arterial geometry variability is present both within and across individuals. To analyze the influence of geometric parameters, blood density, dynamic viscosity and blood velocity on wall shear stress (WSS) distribution in the human carotid artery bifurcation and aneurysm, the computer simulations were run to generate the data pertaining to this phenomenon. In our work we evaluate two prediction models for modeling these relationships: neural network model and k-nearest neighbor model. The results revealed that both models have high prediction ability for this prediction task. The achieved results represent progress in assessment of stroke risk for a given patient data in real time. © 2011 IEEE.


Milankovic I.L.,University of Kragujevac | Mijailovic N.V.,University of Kragujevac | Peulic A.S.,University of Kragujevac | Nikolic D.,Research and Development Center for Bioengineering Bio | And 4 more authors.
FME Transactions | Year: 2015

The main goal of this paper is to describe two different systems that were developed for the purpose of abdominal aortic aneurysm mechanical properties investigation and to present the results of the measurements. The first system is based on the "Bubble Inflated" method and it increases the pressure of physiological saline which affects blood vessel tissue and causes mechanical deformation. The system provides recording the data about the current value of the pressure in the physiological saline by using the appropriate pressure sensor. The second system makes stretches of the vessel tissue in uni-axial direction and save the data about the force and the elongation. Both of these systems use cameras for assessment of the deformation. Obtained results from both systems are used for numerical simulation of computer model for abdominal aortic aneurysm. It gives a new avenue for application of software and hardware systems for determination of vascular tissue properties in the clinical practice. © Faculty of Mechanical Engineering, Belgrade.


Veljkovic D.Z.,Research and Development Center for Bioengineering Bio | Rankovic V.J.,Research and Development Center for Bioengineering Bio | Rankovic V.J.,University of Kragujevac | Pantovic S.B.,University of Kragujevac | And 3 more authors.
Acta of Bioengineering and Biomechanics | Year: 2014

Most of hyperelastic models for the constitutive modeling of the typical mechanical behaviour of the arterial wall tissue in literature are based on the test data from different animals and arteries. This paper is concerned with the material parameter identification of several phenomenological hyperelastic models by fitting the data from five extension-inflation tests of the porcine aorta segment, carried out in our laboratory. A membrane approximation is used to compute stresses and strains achieved during experiments, with usual assumption of material incompressibility. Three orthotropic two-dimensional strain-energy functions, based on use of the Green–Lagrange strains, are fitted to the test data: the well-known Fung’s exponential model; the classical polynomial model with seven constants; and the logarithmic model; and also, two three-dimensional models are employed: polyconvex anisotropic exponential hyperelastic model and the convex isotropic exponential rubber-like hyperelastic constitutive law depending on the first invariant of the right Cauchy–Green deformation tensor. It has been found that isotropic model overestimates values of stresses in axial, and underestimates values of stresses in circumferential direction of artery segment, due to pronounced tissue anisotropy. Also, all two-dimensional models considered give good and similar prediction, while the polyconvex model demonstrates slightly lower performance in the axial direction of artery. © 2014, Institute of Machine Design and Operation. All rights reserved.


Veljkovi D.,Research and Development Center for Bioengineering Bio | Filipovi N.,University of Kragujevac | Koji M.,Research and Development Center for Bioengineering Bio | Koji M.,Methodist Hospital Research Institute
Journal of Mechanics in Medicine and Biology | Year: 2012

In this work we study the effect of asymmetry and axial prestraining on the maximum effective mechanical stress in relatively small human abdominal aortic aneurysm (AAA) during a cardiac cycle. Our model is based on the fluid-structure interaction (FSI) methodology. The arterial wall is modeled using large strain and large deformation formulation, with hyperelastic material behavior, and isotropic nonlinear strain energy function (SEF) fitted to the averaged data set of biaxial tests of AAA tissue specimens. The results confirm that the magnitude of the maximum von Mises stress increases significantly with asymmetry and decreases with aneurysmal length. It is found that the amplitude in variation of the maximum effective stress changes in the same manner as the maximum stress. These results indicate that a short asymmetric AAA is under significant dynamic stress, which might be one of the important factors in a progressive AAA growth over time. It is also found that, in most considered cases, magnitude and amplitude of the maximum effective stress of an AAA is smaller when the artery is pre-stretched in axial direction, while a pre-stretched artery with aneurysm has slightly larger relative volume change of lumen during cardiac cycle than the unstretched AAA. © 2012 World Scientific Publishing Company.


Milasinovic D.Z.,Research and Development Center for Bioengineering Bio | Cvetkovic A.M.,University of Kragujevac | Cvetkovic A.M.,Clinical Center Kragujevac | Ninkovic S.M.,Clinical Center Kragujevac | And 4 more authors.
10th International Workshop on Biomedical Engineering, BioEng 2011 | Year: 2011

In this paper a CFD study of afferent loop syndrome after Billroth II gastric resection is presented. Three-dimensional CFD simulation is used in this study in order to investigate conditions at the duodenal stump after Billroth II gastric resection which may cause duodenal stump blowout. We performed virtual gastric resection using the preoperative Finite Element (FE) model based on MSCT Dicom. Three models after Billroth II gastric resection were created. CFD calculation was performed employing these models with data from literature. We calculated pressure and velocity distribution, as well as saliva and pancreatic juice and bile concentrations. After CFD simulation we had better insight into the processes within the duodenal stump after surgical intervention. This study can be useful for predictions of surgical complications. © 2011 IEEE.


PubMed | Methodist Hospital Research Institute, University of Kragujevac and Research and Development Center for Bioengineering Bio
Type: Comparative Study | Journal: Acta of bioengineering and biomechanics | Year: 2014

Most of hyperelastic models for the constitutive modeling of the typical mechanical behaviour of the arterial wall tissue in literature are based on the test data from different animals and arteries. This paper is concerned with the material parameter identification of several phenomenological hyperelastic models by fitting the data from five extension-inflation tests of the porcine aorta segment, carried out in our laboratory. A membrane approximation is used to compute stresses and strains achieved during experiments, with usual assumption of material incompressibility. Three orthotropic two-dimensional strain-energy functions, based on use of the Green-Lagrange strains, are fitted to the test data: the well-known Fungs exponential model; the classical polynomial model with seven constants; and the logarithmic model; and also, two three-dimensional models are employed: polyconvex anisotropic exponential hyperelastic model and the convex isotropic exponential rubber-like hyperelastic constitutive law depending on the first invariant of the right Cauchy-Green deformation tensor. It has been found that isotropic model overestimates values of stresses in axial, and underestimates values of stresses in circumferential direction of artery segment, due to pronounced tissue anisotropy. Also, all two-dimensional models considered give good and similar prediction, while the polyconvex model demonstrates slightly lower performance in the axial direction of artery.

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