Search for: ultrasonic-imaging
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    Experimental Study of Microbubbles Generation as a Contrast Agent in Blood, to Determine the Blood Flow by Echo-PIV Method

    , M.Sc. Thesis Sharif University of Technology Salari, Alinaghi (Author) ; Shafiee, Behshad (Supervisor)
    Today microbubbles are broadly used as ultrasound contrast agents. These bubbles enhance the image resolution of B-mode pictures. Flow focusing in microchannels could provide us the goal of one-size bubbles generation. Microbubbles could use as tracers in Echo_PIV method to determine the velocity profile in main body vessels such as carotid. In this paper we introduce a new production method to fabricate a low-cost microchannel for preparing Microbubble contrast agents (less than 50 microns) by using some surface active agents and a viscosity enhancing material to obtain appropriate Microbubbles with desired life time and stability for any in vitro infusion for velocity measurement. By... 

    Design and Implementation of a Fixed Distance to Object Imaging System using a 3-DOF. Table, with Integrated Software System for Acquisition, Processing and Display of Signals

    , M.Sc. Thesis Sharif University of Technology Karimi, Fateme (Author) ; Ravanbod, Hossein (Supervisor)
    Deriving the shape, area, volume, and orientation of a defect from the ultrasonic nondestructive testing images of the oil pipelines, paves the way for the estimation of its severity. This paper describes the design and implementation of an automatic structure which can move an ultrasonic probe over the surface of a test sample, while preserving the distance, i.e. stand-off, between them, whatever the shape of the surface might be. The fixed stand-off is implemented, closing a feedback loop with a distance meter sensor. Also an integrated software environment is developed for the control of the table, data acquisition, data processing and displaying the results. After acquiring the... 

    Speckle noise reduction of ultrasound images using M-band wavelet transform and wiener filter in a homomorphic framework

    , Article 1st International Conference on BioMedical Engineering and Informatics, BMEI 2008, Sanya, Hainan, 27 May 2008 through 30 May 2008 ; Volume 2 , 2008 , Pages 510-515 ; 9780769531182 (ISBN) Vosoughi, A ; Shamsollahi, M. B ; Sharif University of Technology
    In this paper we make use of M-band discrete wavelet transform (MDWT) and Wiener filter for speckle noise suppression of ultrasound images. Assuming multiplicative model for speckle noise, by applying logarithmic transform to noisy observation we convert multiplicative noise to additive one. Then, speckle noise can be reduced by taking the M-band wavelet transform of log-transformed observation and employing an adaptive thresholding technique. In order to improve the performance of this denosing approach, we propose a preprocessing stage which exploits Wiener filtering. Through this stage logtransformed observation is separated into two images and then each of these two images is denoised... 

    A holey cavity for single-transducer 3D ultrasound imaging with physical optimization

    , Article Signal Processing ; Volume 179 , 2021 ; 01651684 (ISSN) Ghanbarzadeh Dagheyan, A ; Heredia Juesas, J ; Liu, C ; Molaei, A ; Martinez Lorenzo, J. A ; Vosoughi Vahdat, B ; Ahmadian, M. T ; Sharif University of Technology
    Elsevier B.V  2021
    Within the compressive sensing (CS) framework, one effective way to increase the likelihood of successful signal reconstruction is to employ random processes in the construction of the sensing matrix. This study presents a 3D holey cavity, with diverse frequency modes, to spectrally code, that is, randomize, the ultrasound wave fields. The simulated results show that the use of such a cavity enables imaging simple or complex targets, such as spheres or the letter E, by only a single transceiver—something that is not possible without the use of a coding structure like the cavity. The effect of noise on imaging results and the size of the targets on the first-order Born approximation (BA) are... 

    Design of a broadband high frequency ultrasound transducer for skin imaging

    , Article 6th RSI International Conference on Robotics and Mechatronics, IcRoM 2018, 23 October 2018 through 25 October 2018 ; 2019 , Pages 261-265 ; 9781728101279 (ISBN) Babazadeh Khameneh, A ; Chabok, H. R ; Nejat, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    This paper discusses the design of a high frequency wide bandwidth ultrasound transducer with the center frequency of 50 MHz and an aperture diameter of 3 mm for medical ultrasonic imaging. The piezoelectric material used in this design is Lithium Niobate. The design is verified by both KLM equivalent circuit and spatial impulse response method as used in FIELD II software and the theoretical imaging resolution has been calculated as 50 um axially and 80 um laterally. The possible applications of this probe are skin layer imaging, tumor detection and superficial blood flow measurement  

    Estimation of Tissue Deformation from Ultrasonic Images in Needle Insertion Procedures

    , M.Sc. Thesis Sharif University of Technology Askari Karchegani, Maziyar (Author) ; Jahed, Mehran (Supervisor)
    In recent years, steering percutaneous needle insertions with the aid of soft tissue modeling techniques has been of great interest. In this thesis an optical flow based motion estimation method is used to estimate tissue deformation. It also addresses needle tracking in ultrasound images for prostate biopsy and brachytherapy. The thesis reviews reported methods on needle insertion using ultrasound imagery and further introduces a projection based method (Hough Transform) for needle tracking. Considering that ultrasound images have releatively low contrast and high speckle noise content, diffusion and wavelet-based filtering methods are employed as noise reduction techniques. Next, an... 

    Ultrasound medical image speckle reduction using fourth-order partial differential equation

    , Article 2011 7th Iranian Conference on Machine Vision and Image Processing, MVIP 2011 - Proceedings, 16 November 2011 through 17 November 2011 ; November , 2011 , Page(s): 1 - 5 ; 9781457715358 (ISBN) Keikhosravi, A ; Hashemi Berenjabad, S. H ; Sharif University of Technology
    One of the drawbacks to post-process and to interpret ultrasound medical images is speckle noise. In this paper we used fourth-order partial differential equation method proposed by Lysaker et al. for speckle reduction of ultrasound images. We used two groups of images first was the synthesized noisy image and second is real ultrasonic images. A comparison between our results and to other methods showed that PDE has better SNR and PSNR in most levels of speckle  

    A Physiological model-based study of flow-mediated dilation in peripheral arteries using finger photoplethysmogram signal

    , Article 2017 24th Iranian Conference on Biomedical Engineering and 2017 2nd International Iranian Conference on Biomedical Engineering, ICBME 2017, 30 November 2017 through 1 December 2017 ; 2018 ; 9781538636091 (ISBN) Habib Parsafar, M ; Zahedi, E ; Vosoughi Vahdat, B ; Sharif University of Technology
    Flow-mediated dilation measurement in the brachial artery using ultrasound imaging (FMD-US) is a common noninvasive procedure for endothelial function evaluation in the peripheral arteries. As FMD-US is operator-dependent and involves onerous equipment, its use has been mostly confined to research settings. In this paper, we propose to use the more accessible finger photoplethysmogram signal in conjunction with the FMD test (FMD-PPG) as a surrogate method. To this end, a tube-load physiological model of the upper arterial path in the arm is developed. Signals acquired from young and elderly subjects (N=20) are then investigated using model parameter estimation by the genetic algorithm. Our... 

    Application of neuro-fuzzy techniques in oil pipeline ultrasonic nondestructive testing

    , Article NDT and E International ; Volume 38, Issue 8 , 2005 , Pages 643-653 ; 09638695 (ISSN) Ravanbod, H ; Sharif University of Technology
    This paper presents a novel approach to the problem of nondestructive pipeline testing using ultrasonic imaging. The identification of the flaw type and its dimensions are the most important problems in the pipeline inspection. Unlike typical methods, a decision based neural network is used for the detection of flaws. We train a generalized regression neural network to determine the dimensions of the corrosions and generate the whole image of both the internal and external walls of the oil pipeline. As an improvement to the detection algorithm, we introduce fuzzy decision-based neural network algorithms for the detection and classification of the corrosions. The simulation and experimental... 

    Optical flow-based motion estimation of ultrasonic images for force estimation in percutaneous procedures: Theory and experimental validation

    , Article IECON Proceedings (Industrial Electronics Conference), 25 October 2012 through 28 October 2012 ; October , 2012 , Pages 1557-1560 ; 9781467324212 (ISBN) Maghsoudi, A ; Jahed, M ; Sharif University of Technology
    In recent years, there hass been a pronounced emphasis on percutaneous needle steering with the aid of advanced soft tissue modeling techniques. In this work an optical flow based motion estimation method is used to estimate the force applied to the needle by the soft tissue during percutaneous applications. The study considers Finite Element Model (FEM) of the tissue evaluated by the deformation data acquired through the optical flow method. To represent the soft tissue behavior, dynamic FEM with Rayleigh damping and viscoelastic models are used. The method is validated experimentally through offline evaluation of the ultrasonic images of the chicken breast punctured by a needle. The force... 

    Flaw characterization in ultrasonic non-destructive testing method using exponential modeling

    , Article Conference Record - IEEE Instrumentation and Measurement Technology Conference ; 2013 , Pages 1676-1679 ; 10915281 (ISSN) ; 9781467346221 (ISBN) Ravanbod, H ; Karimi, F ; Amindavar, H ; Sharif University of Technology
    Determining the shape, area, volume, and direction of flaws using ultrasonic imaging of metallic pieces, is a method estimating the severity of their defects. Different methods are used to process ultrasound images. Among these methods are spectral analyses, statistical, mathematical and intelligent methods. Within each of these, there are some advantages as well as limitations. Prony algorithm, which has been used as a parametric method for extracting exponential components of a signal, has several applications in signal modeling, system identification and classification. In this paper, after simulating pieces of oil pipeline, digital Wavelet transform has been used to reduce the noise of... 

    Abdominal hollowing and lateral abdominal wall muscles' activity in both healthy men & women: An ultrasonic assessment in supine and standing positions

    , Article Journal of Bodywork and Movement Therapies ; Volume 15, Issue 1 , Jan , 2011 , Pages 108-113 ; 13608592 (ISSN) Manshadi, F. D ; Parnianpour, M ; Sarrafzadeh, J ; Azghani, M. R ; Kazemnejad, A ; Sharif University of Technology
    The objective of this study was to investigate the effects of Abdominal Hollowing (AH) maneuver on External Oblique (EO), Internal Oblique (IO) and Transversus Abdominis (TrA) muscles in both healthy men and women during the two postures of supine and upright standing. The study was conducted on 43 asymptomatic volunteers (22 males and 21 females) aged 19-44 (27.8 ± 6.4) years. Rehabilitative Ultrasonic Imaging (RUSI) was simultaneously performed to measure muscle thickness in both rest and during AH maneuvers while activation of the TrA during AH was controlled by Pressure Biofeedback (PBF) device. Mixed-model ANOVA with repeated measures design, and Pearson correlation tests were used to... 

    Magnetic resonance imaging tracking of stem cells in vivo using iron oxide nanoparticles as a tool for the advancement of clinical regenerative medicine

    , Article Chemical Reviews ; Volume 111, Issue 2 , November , 2011 , Pages 253-280 ; 00092665 (ISSN) Mahmoudi, M ; Hosseinkhani, H ; Hosseinkhani, M ; Boutry, S ; Simchi, A ; Shane Journeay, W ; Subramani, K ; Laurent, S ; Sharif University of Technology
    Fetal stem cells, which can be isolated from the organs of fetuses, differentiate along multiple lineages. Their advantages over their adult counterparts include better intrinsic homing and engraftment and lower immunogenicity, and they are less ethically contentious. It is noteworthy that Mesenchymal Stem Cells (MSC) can be activated and mobilized at the site of damaged tissue. Since vascular delivery suffers from a pulmonary first pass effect, direct or systemic injection of MSCs into the damaged tissue is preferred, particularly in the case of versatile tissue ischemia. Ultrasound applies acoustic energy with a frequency above human hearing (20 kHz). Ultrasound imaging or sonography... 

    Tele-echography of moving organs using an Impedance-controlled telerobotic system

    , Article Mechatronics ; Volume 45 , 2017 , Pages 1339-1351 ; 09574158 (ISSN) Sharifi, M ; Salarieh, H ; Behzadipour, S ; Tavakoli, M ; Sharif University of Technology
    Elsevier Ltd  2017
    A novel impedance-controlled teleoperation system is developed for robot-assisted tele-echography of moving organs such as heart, chest and breast during their natural motions (beating and/or breathing). The procedure of devising the two impedance models for the master and slave robots is developed such that (a) the slave robot holding the ultrasound (US) probe follows the master trajectory but complies with the oscillatory interaction force of the moving organ, and (b) the sonographer receives feedback from the non-oscillatory portion of the slave-organ interaction force via the master robot similar to the haptic feedback received in echography of a stationary organ. These goals are... 

    Noninvasive estimation of tissue temperature via high-resolution spectral analysis techniques

    , Article IEEE Transactions on Biomedical Engineering ; Volume 52, Issue 2 , 2005 , Pages 221-228 ; 00189294 (ISSN) Nasiri Amini, A ; Ebbini, E. S ; Georgiou, T. T ; Sharif University of Technology
    We address the noninvasive temperature estimation from pulse-echo radio frequency signals from standard diagnostic ultrasound imaging equipment. In particular, we investigate the use of a high-resolution spectral estimation method for tracking frequency shifts at two or more harmonic frequencies associated with temperature change. The new approach, employing generalized second-order statistics, is shown to produce superior frequency shift estimates when compared to conventional high-resolution spectral estimation methods Seip and Ebbini (1995). Furthermore, temperature estimates from the new algorithm are compared with results from the more commonly used echo shift method described in Simon...