Loading...
Search for:
perfusion
0.006 seconds
Standard SPECT myocardial perfusion estimation from half-time acquisitions using deep convolutional residual neural networks
, Article Journal of Nuclear Cardiology ; 2020 ; AmirMozafari Sabet, K ; Arabi, H ; Pourkeshavarz, M ; Teimourian, B ; Ay, M. R ; Zaidi, H ; Sharif University of Technology
Springer
2020
Abstract
Introduction: The purpose of this work was to assess the feasibility of acquisition time reduction in MPI-SPECT imaging using deep leering techniques through two main approaches, namely reduction of the acquisition time per projection and reduction of the number of angular projections. Methods: SPECT imaging was performed using a fixed 90° angle dedicated dual-head cardiac SPECT camera. This study included a prospective cohort of 363 patients with various clinical indications (normal, ischemia, and infarct) referred for MPI-SPECT. For each patient, 32 projections for 20 seconds per projection were acquired using a step and shoot protocol from the right anterior oblique to the left posterior...
Malignancy determination of tumors using perfusion MRI
, Article 2009 International Conference on Image Processing, Computer Vision, and Pattern Recognition, IPCV 2009, Las Vegas, NV, 13 July 2009 through 16 July 2009 ; Volume 2 , 2009 , Pages 906-909 ; 9781601321190 (ISBN) ; Soltanian Zadeh, H ; Akhlaghpour, S ; Fatemi Zadeh, E ; United States Military Academy, Network Science Center; HST Harvard Univ. MIT, Biomed. Cybern. Lab.; Argonne's Leadersh. Comput. Facil. Argonne Natl. Lab.; Univ. Illinois Urbana-Champaign, Funct. Genomics Lab.; University of Minnesota, Minnesota Supercomputing Institute ; Sharif University of Technology
2009
Abstract
Our purpose was to determine whether perfusion MR imaging can be used for malignancy determination of tumors. Relative cerebral blood flow (rCBF) is a commonly used perfusion magnetic resonance imaging (MRI) technique for the evaluation of malignancy. The goal of our study was to determine the usefulness of this parameter in malignancy determination of tumors using Independent Component Analysis (ICA)
Computational modeling of media flow through perfusion-based bioreactors for bone tissue engineering
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 234, Issue 12 , 2020 , Pages 1397-1408 ; Bohlouli, M ; Adavi, K ; Paknejad, Z ; Rezai Rad, M ; khani, M. M ; Salehi-Nik, N ; Khojasteh, A ; Sharif University of Technology
SAGE Publications Ltd
2020
Abstract
Bioreactor system has been used in bone tissue engineering in order to simulate dynamic nature of bone tissue environments. Perfusion bioreactors have been reported as the most efficient types of shear-loading bioreactor. Also, combination of forces, such as rotation plus perfusion, has been reported to enhance cell growth and osteogenic differentiation. Mathematical modeling using sophisticated infrastructure processes could be helpful and streamline the development of functional grafts by estimating and defining an effective range of bioreactor settings for better augmentation of tissue engineering. This study is aimed to conduct computational modeling for newly designed bioreactors in...
Feasibility Study of Capillary Blood Viscosity Estimation using MRI
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Ashoor, Mansoor (Co-Advisor)
Abstract
Magnetic resonance imaging is one of non-invasive methods to measure the hemodynamic and morphologic parameters of tissues, especially brain tissues. Hemodynamic parameters monitoring in brain tissue is of significant importance in many majors such as detection of tumor occurrence, brain abnormalities, and track of treatment procedures. Blood is a suspension, comprised of plasma, red blood cells, white blood cells, platelet, etc. Plasma is a Newtonian fluid which is composed of proteins and has a constant viscosity in body temperature. Rheological properties of blood are highly dependent on mechanical and rheological properties of its cells and this dependence is multiplied in narrow vessels...
Stem Cell Proliferation and Differentiation in Bioreactors
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Manouchehr (Supervisor) ; Alemzadeh, Iran (Supervisor)
Abstract
In this study, differentiation of rabbit embryonic-derived mesenchymal stem cells to osteogenic cells has been characterized. Bone tissue engineering is based upon the understanding of bone tissue construct and it’s formation in-vivo, and the Preparation of tissue engineered bone constructs to repair large size defects is it’s major goal. We sought to investigate the combined effect of three elemnts of tissue engineering: cells, scaffolds and growth factors. Mesenchymal stem cells are unspecialized cells which due to their unlimited self-renewal capacity and the remarkable ability to differentiate along multiple linage pathways are natural choice for application in tissue repair and...
The effect of temperature on eccentric contraction-induced isometric force loss in isolated perfused rat medial gastrocnemius muscle
, Article Tehran University Medical Journal ; Volume 66, Issue 6 , 2008 , Pages 388-395 ; 16831764 (ISSN) ; Keshavarz, M ; Gharibzadeh, S ; Marvi, H ; Mosayebnejad, J ; Ebrahimi Takamjani, E ; Sharif University of Technology
Tehran University of Medical Sciences
2008
Abstract
Background: The typical features of eccentric exercise-induced muscle damage are delayed-onset muscle soreness (DOMS) and prolonged loss of muscle strength. It has been shown that passive warmth is effective in reducing muscle injury. Due to the interaction of different systems in vivo, we used isolated perfused medial gastrocnemius skeletal muscle to study the direct effect of temperature on the eccentric contraction-induced force loss. Methods: After femoral artery cannulation of a rat, the left medial gastrocnemius muscle was separated and then the entire lower limb was transferred into a prewarmed (35oC) chamber. With the chamber temperature at 31, 35 and 39oC before and during eccentric...
Cardiac contraction motion compensation in gated myocardial perfusion SPECT: a comparative study
, Article Physica Medica ; Volume 49 , 2018 , Pages 77-82 ; 11201797 (ISSN) ; Rahmim, A ; Fatemizadeh, E ; Akbarzadeh, A ; Farahani, M. H ; Farzanefar, S ; Ay, M. R ; Sharif University of Technology
Associazione Italiana di Fisica Medica
2018
Abstract
Introduction: Cardiac contraction significantly degrades quality and quantitative accuracy of gated myocardial perfusion SPECT (MPS) images. In this study, we aimed to explore different techniques in motion-compensated temporal processing of MPS images and their impact on image quality and quantitative accuracy. Material and method: 50 patients without known heart condition underwent gated MPS. 3D motion compensation methods using Motion Freezing by Cedars Sinai (MF), Log-domain Diffeomorphic Demons (LDD) and Free-Form Deformation (FFD) were applied to warp all image phases to fit the end-diastolic (ED) phase. Afterwards, myocardial wall thickness, myocardial to blood pool contrast, and...
SAR thresholds for electromagnetic exposure using functional thermal dose limits
, Article International Journal of Hyperthermia ; Volume 34, Issue 8 , 2018 , Pages 1248-1254 ; 02656736 (ISSN) ; Paulides, M. M ; Van Rhoon, G. C ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
Background and purpose: To protect against any potential adverse effects to human health from localised exposure to radio frequency (100 kHz–3 GHz) electromagnetic fields (RF EMF), international health organisations have defined basic restrictions on specific absorption rate (SAR) in tissues. These exposure restrictions incorporate safety factors which are generally conservative so that exposures that exceed the basic restrictions are not necessarily harmful. The magnitude of safety margin for various exposure scenarios is unknown. This shortcoming becomes more critical for medical applications where the safety guidelines are required to be relaxed. The purpose of this study was to quantify...
An optimized procedure to develop a 3-dimensional microfluidic hydrogel with parallel transport networks
, Article International Journal for Numerical Methods in Biomedical Engineering ; 2018 ; 20407939 (ISSN) ; Salehi, Z ; Shokrgozar, M. A ; Mashayekhan, S ; Sharif University of Technology
Wiley-Blackwell
2018
Abstract
The development of microfluidic hydrogels is an attractive method to generate continuous perfusion, induce vascularization, increase solute delivery, and ultimately improve cell viability. However, the transport processes in many in vitro studies still have not been realized completely. To address this problem, we have developed a microchanneled hydrogel with different collagen type I concentrations of 1, 2, and 3 wt% and assessed its physical properties and obtained diffusion coefficient of nutrient within the hydrogel. It is well known that microchannel geometry has critical role in maintaining stable perfusion rate. Therefore, in this study, a computational modeling was applied to...
The influence of temperature alterations on eccentric contraction-induced isometric force and desmin loss in ratmedial gastrocnemius muscle
, Article Journal of Medical Sciences ; Volume 8, Issue 2 , 2008 , Pages 162-169 ; 16824474 (ISSN) ; Keshavarz, M ; Gharibzadeh, S ; Sotodeh, M ; Marvi, H ; Mosayebnejad, J ; Ebrahimi Takamjani, I ; Sharif University of Technology
2008
Abstract
In this study isolated perfused rat muscle was used to examine the direct effect of temperature changes on the eccentric contraction-induced force and desmin loss. The left medial gastrocnemius muscle was separated and the entire lower limb was transferred into a prewarmed (35°C) organ bath. Temperature was adjusted to 31 or 39°C before and during eccentric contractions. Maximal isometric force and desmin loss were measured after 15 isometric or eccentric contractions. According to our data, organ bath temperature changes before or during eccentric contractions had no significant effect on force loss. However, a strong correlation between desmin loss and temperature changes before (r = 0.93,...
Introducing a new definition towards clinical detection of microvascular changes using diffusion and perfusion MRI
, Article Scientia Iranica ; Volume 12, Issue 1 , 2005 , Pages 109-115 ; 10263098 (ISSN) ; Jiang, Q ; Chopp, M ; Jahed, M ; Sharif University of Technology
Sharif University of Technology
2005
Abstract
Based on MRI diffusion and perfusion, a new criterion for detection and the healing progress of damaged tissue is suggested. The study is based on the ratio of capillary radii in symmetrical damaged and normal tissue neighboring spaces. The Apparent Diffusion Coefficient (ADC) and Cerebral Blood Flow (CBF) were measured in the brain tissues of six male Wistar rats utilizing suggested MRI measurement techniques. The ADC values of damaged and normal regions were (392 ± 34.1) × 10-6 mm2s-1 and (659 ± 40.7) × 10-6 mm2s-1, respectively. The CBF values of damaged and normal regions were 14.5 ± 10.13 ml/min/ 100 g and 125 ± 41.03 ml/min/100 g, respectively. The geometrical parameters of the...
Comparative study of commercial media to improve GMP manufacturing of recombinant human interferon β-1a by CHO cells in perfusion bioreactor
, Article Cytotechnology ; Volume 74, Issue 6 , 2022 , Pages 669-680 ; 09209069 (ISSN) ; Karimi Mostofi, R ; Sattarzadeh, A ; Shahbazi, M ; Aghazadeh, H ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Chinese hamster ovary cells are the main cellular factories for production of a wide range of recombinant proteins in biopharmaceutical industry. Recombinant human Interferon beta-1a (rh-IFN β-1a), as a cytokine is broadly used to treat multiple sclerosis. In this work, the cell line producing rh-IFN β-1a was studied to improve cell density along with the specific expression. For this reason different cell culture experiments were done using different commercial serum-free media to find the appropriate media providing higher cell density. It was shown DMEMF12, DMEM:ProCHO5, and CHO-S-SFM II led to higher cell density and shorter doubling time. Next, using these media, fed-batch, and...
Fabrication of biocompatible titanium scaffolds using space holder technique
, Article Journal of Materials Science: Materials in Medicine ; Volume 23, Issue 10 , 2012 , Pages 2483-2488 ; 09574530 (ISSN) ; Sadrnezhaad, S. K ; Shokrgozar, M. A ; Bonakdar, S ; Sharif University of Technology
Springer
2012
Abstract
Open-pore titanium scaffolds were fabricated by sintering of compressed mixtures of TiH1.924 and urea. Spherical and irregular shaped space holders were used to investigate the effect of pore shape on cellular behavior. After removal of the space holder, the shape of the spacers was replicated to the pores. Average diameter of the pores was in the range of 300-600 lm. SEM images showed that titanium hydride resulted in higher surface roughness and larger micro porosities than pure titanium. In vitro evaluationswere carried out by using MTT assay, measuring alkaline phosphatase activity and alizarin red staining in flow perfusion bioreactor for cell culture. Observations revealed excellent...