Loading...
Search for: zahedi--edmond
0.005 seconds

    The Effect of Electroporation on Ultrasund Signals

    , M.Sc. Thesis Sharif University of Technology Dashti, Ali (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    In this thesis, a cellular model of electroporation process and its detection by ultrasound signals is proposed. Electroporation is permeabilization of the cell membrane, caused by an external electric field. The resulted pores open cell’s membrane to large or hydrophilic molecules. The process of Electroporation has been used in Gene therapy and treatment of solid tumors. In this project, first we made a phantom of electroporated tissue and a phantom of normal tissue and then we simulated their responses to a linear array ultrasound transducer. By comparision of received signals from phantoms the probable effect of electroporation on ultrasound RF signals revealed. Results show up to 5 %... 

    Modeling Brachial Blood Pressure by Using Finger PPG Signal

    , M.Sc. Thesis Sharif University of Technology Asadpour, Abdoreza (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    Nowadays, all of the devices that measure blood pressure commercially at home are using wrist or arm cuffs preventing the systolic or diastolic blood pressure from being measured continuously. Various parameters such as blood flow with some degree of correlation with blood pressure that can be measured noninvasively have been suggested. However, these parameters do not produce accurate estimates for blood pressure. Pulse Transit Time (PTT) which is defined as the interval between the R peak of ECG signal and the next PPG signal valley has shown to have over 90% correlation with systolic blood pressure in past studies. In this thesis, the relationship between the value of the systolic blood... 

    Meaurement of Flow Mediated Dilation Using Photoplethysmography

    , M.Sc. Thesis Sharif University of Technology Goldoozian, Layli Sadat (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    Endothelial cells cover the inner surface of blood vessels. In response to different physical (such as reactive hyperemia-RH) and pharmacological stimuli, they maintain homeostasis by changing the vascular diameter (by releasing chemical agents like nitric oxide). The endothelium inability to respond to metabolic need (endothelial dysfunction) is an early marker of cardiovascular diseases such as atherosclerosis. Flow mediated dilation (FMD) measurement using ultrasound imaging (FMD-US) has been established as a standard method for assessing the endothelial function. Recently, a less skilled-operator demanding method has been proposed based on the photoplethysmographic (PPG) signal changes... 

    Ultrasound Intensity Exposimetry in Physiotherapy Devices using Micro-Bubbles

    , M.Sc. Thesis Sharif University of Technology Rezayat, Ehsan (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    Routine ultrasound calibration methods have some restrictions such as: low bandwidth, low frequency resolution, limited spatial resolution, the high cost of test and risk of damage to the transducer when exposed to high powers. In this thesis, a new technique based on microbubble resonance is proposed. Non-linear resonating microbubbles produce harmonics;the first harmonic may be masked by reflection from larger microbubbles as well as unwanted reflections which cause ambiguity in the determination of the amplitude of the excited pressure. Therefore, the second harmonic is used, with a single characteristic peak. In order to model the physical phenomenon, the second harmonic generated in the... 

    , M.Sc. Thesis Sharif University of Technology Malek Mohammadi, Mahsa (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    Cardiovascular (CV) system is very similar to a wireless communication system in which a common input signal from the heart is fed into different arterial channels throughout different body parts. By putting multiple sensors on different peripheral body sites effects of this circulation from the heart can be recorded and be used as inputs for different multi channel blind system identification (BSI) methods for estimation of arterial channel dynamics. This Thesis is defined in order to investigate different BSI methods capability in CV characterization. To achieve this goal photoplethysmogram signals has been used as primary sensory recorded effect of heart function at three different... 

    Development of a Wrist PPG Probe for the Measurement of Radial Artery Diameter

    , M.Sc. Thesis Sharif University of Technology Keikhosravi, Adib (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    Inability of endothelial cells in responding to metabolic needs (endothelial dysfunction,) is a sign of heart diseases like atherosclerosis and vascular stenosis. Recently, a new method using finger PPG signal has been proposed to determine endothelial function in response to reactive hypertension (RH.) PPG-based endothelial function assessment results are not fully correlated with ultrasound FMD tests, and this is because of some auto-regulation phenomena in the fingertip. It is expected that such problems will not exist in larger arteries, like the radial artery. The goal of this project is to acquire the PPG signal from the radial artery as it is proportional to blood volume changes in... 

    Simulating Light Propagation and Photoplethysmography Signal Generation over the Radial Artery

    , M.Sc. Thesis Sharif University of Technology Hosseini, Soheil (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    Measuring the human brachial arterial diameter has significant applications in medical research. This is conventionally carried out using ultrasonography which is costly and operator-skill dependent. The objective of this project is to come up with substitute solutions based on optical measurement. Reflectance photoplethysmography (PPG) over the radial artery has been considered to this end. Monte Carlo method has been employed to simulate light propagation in the wrist area, along with a model comprising tissue, artery and bone, made of simple solid geometries. Functions of optical parameters such as refractive index, absorption coefficient, scattering coefficient and anisotropy factor have... 

    Blood Pressure Measurement by using Pulse Transit Time

    , M.Sc. Thesis Sharif University of Technology Mazaheri, Samaneh (Author) ; Zahedi, Edmond (Supervisor) ; Jahed, Mehran (Supervisor)
    Abstract
    Continuous and non-invasive blood pressure (BP) measurement systems generally utilize applanation tonometry and vascular unloading. Some of them satisfies the AAMI standards (|mean|<5, |SD|<8). Unfortunately they are hardly to be widely affordable due to the complicated mechanical structure and high production cost. Till now those devices are seldom being used in operation room and generally used in clinical researches. In 2000, a linear model using pulse transit time (PTT) to continuous and non-invasive blood pressure (BP) measurement was proposed. Due to the nonlinear performance parameters of the arteries, researchers have used nonlinear models to promote this method. Although the... 

    Analyzing the Endothelial Function by Means of Photoplethysmogram Signal Modeling

    , M.Sc. Thesis Sharif University of Technology Amiri, Mina (Author) ; Zahedi, Edmond (Supervisor) ; Behnia, Fereidoon (Supervisor)
    Abstract
    The endothelial (the artery inner lumen cells) function is associated with cardiovascular risk factors. Its assessment methods can be classified into the two groups of invasive and noninvasive ones. The most widely used method among the current non-invasive tests employed in research settings is flow-mediated dilation (FMD). This technique measures endothelial function by inducing reactive hyperemia via the temporary arterial occlusion and measuring the resultant relative increase in the blood vessel diameter via ultrasound. The high price and large size of the device, and being operator dependent are the limitation of this method. In this work, we propose using the photoplethysmogram (PPG)... 

    Modeling the Endothelial Function in the Brachial Artery Using Photoplethysmography

    , M.Sc. Thesis Sharif University of Technology Mashayekhi, Ghoncheh (Author) ; Zahedi, Edmond (Supervisor) ; Jahed, Mehran (Supervisor)
    Abstract
    Flow Mediated Dilation (FMD) is a non-invasive method for endothelial function assessment providing an index extracted from ultrasonic B-mode images. Although utilized in the research community, the difficulty of its application and high cost of ultrasonic device prevent it from being widely used in clinical settings. In this study we show that substituting the ultrasonic device with more easily handled and low cost photoplethysmography and electrocardiography is possible. We introduce new indices based on the photoplethysmogram (PPG) and electrocardiogram (ECG) and show that they are correlated with the ultrasound-based FMD index. To this end, conventional ultrasound FMD test was carried... 

    Prediction of Coronary Angiography Results by Flow Mediated Dilation Assessments with Photoplethysmography

    , M.Sc. Thesis Sharif University of Technology Hosseini, Zahra Sadat (Author) ; Zahedi, Edmond (Supervisor) ; Fakhrzadeh, Hossein (Supervisor)
    Abstract
    Cardio Vascular Diseases (CVD) is currently the most important cause of mortality in the world. Coronary artery disease (CAD-with 3 major epicardial vessels) is one of the significant CVD. Coronary angiography remains the gold standard for identifying the presence and absence of stenosis due to CAD. It is performed by inserting a catheter into the coronary artery, directly injecting radiopaque contrast material there and recording radiographic images in different view of arteries. Images of this invasive way show severity and area of stenosis.
    A sign of CAD is endothelial dysfunction (inner artery layer) in peripheral arteries like the brachial artery. Due to a significant correlation... 

    Solution of the Direct Problem of Electrical Impedance Tomography using the Finite Element Method

    , M.Sc. Thesis Sharif University of Technology Beik Khormizi, Hamed (Author) ; Zahedi, Edmond (Supervisor) ; Vosoughi Vahdat, Bijan (Supervisor)
    Abstract
    Today, the various medical imaging methods have had a wide development in achieving lower cost, lower volume, higher safety, higher quality and being more noninvasive. Compared with the other existing methods, Electrical Impedance Tomography (EIT) can solely meet the first three objectives. Although there have been some presented methods with significant progress, this method has still much lower quality than the other methods (like magnetic resonance imaging or X-ray imaging). In EIT, via the injection of an electrical current (in frequencies between 1-100 kHz and the amplitude between 1-5 mA) and the measurement of the voltage induced in the border areas of the body, a map of the internal... 

    Determination of the Degree of Occlusion of Coronary Arteries by Processing Angiography Images

    , M.Sc. Thesis Sharif University of Technology Ghalehnovi, Mahboobeh (Author) ; Zahedi, Edmond (Supervisor) ; Fatemizade, Emadeddin (Supervisor)
    Abstract
    Cardiovascular disease is considered as the most important cause of death in the world. The coronary vessels, with three main arteries, has quite important. Coronary angiography is still the most common modality for physicians to assess the severity of vessel narrowing or stenosis during percutaneous coronary intervention procedure. For this procedure, a thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck. The tube is threaded into your coronary arteries, and the dye is released into your bloodstream. X-ray pictures are taken while the dye is flowing through the coronary arteries. Physicians evaluate angiographic images visually with... 

    Modeling the Relationship between Central Aortic Pressure and Radial Photoplethysmogram in Flow-mediated Dilation Test

    , Ph.D. Dissertation Sharif University of Technology Parsafar, Mohammad Habib (Author) ; Vosughi Vahdat, Bijan (Supervisor) ; Zahedi, Edmond (Supervisor)
    Abstract
    According to the World Health Organization, about 35% of deaths worldwide are due to cardiovascular diseases, therefore the evaluation of vascular endothelial function has great prognostic and diagnostic value for cardiovascular diseases. The conventional noninvasive method for endothelial function evaluation is the measurement of flow-mediated dilation in brachial artery using ultrasound imaging (FMD-US). As the accuracy of FMD-US depends on the operator's skill and the resolution of the ultrasound images, this method has not been adopted. In this work, we propose to use a low cost, easily-accessible surrogate signal, the photoplethysmogram (PPG) to implement the FMD test. Whereas previous... 

    Capacitive Copling for Energy Transmission to Implant

    , M.Sc. Thesis Sharif University of Technology Ashiri, Mehrangiz (Author) ; Zahedi, Edmond (Supervisor) ; Vosughi Vahdat, Bijan (Supervisor)
    Abstract
    Neural prostheses (NPs) based on capacitive coupling method including sur-face NPs, implanted or subcutaneous NPs and Stimulus Route System (SRS) are the common NPs used for rehabilitation applications. SRS is a kind of capacitive coupling and the latest version of the mentioned neural prosthesis used for restoring sensory and motor functions caused by spinal cord and brain disorders. In addition to some superiorities of capacitive coupling compared to other methods (inductive coupling, batteries, energy harvesters and so on) such as at plates structure and consequently ease of manufacturing, ability to transfer data and power with different operating frequency and hence remov-ing... 

    Modeling of the Cardiovascular System using Breathing Stimuli for Evaluation of the Autonomic Nervous System

    , Ph.D. Dissertation Sharif University of Technology Goldouzian, Layli Sadat (Author) ; Zahedi, Edmond (Supervisor) ; Jehed, Mehran (Supervisor) ; Zarzoso, Vicente (Supervisor)
    Abstract
    Autonomic nervous system (ANS) controls involuntary activities of the body, e.g. heartbeat function and blood circulation. Common tests used for evaluation of the functionality of ANS system in regulation of the cardiovascular system include heart rate variability (HRV) analysis and studying the changes in heart rate or blood pressure during deep respiration, sit-to-stand or head-up tilt table test and Valsalva maneuver. Test parameters affect the amplitude of the variations of the cardiovascular signals. Therefore, in the recent years, analysis and modeling of the interaction between the relevant signals, e.g. heart rate, blood pressure and respiration, have been widely used for the... 

    Time Delay Estimation between Two Photoplethysmography Signals under Noisy Conditions

    , M.Sc. Thesis Sharif University of Technology Teymoori, Parisa (Author) ; Zahedi, Edmond (Supervisor) ; Shamsollahi, Mohammad Bagher (Supervisor)
    Abstract
    In this project, a processing algorithm is approached which is resistant against environmental and motion noises to find the pulse transmission time using two photoplethysmography signals. For this purpose, a new processing framework is checked and generalized for photoplethysmography signals. Already, this processing framework had impressive results. The considered processing method is obtained by offering a dynamic model for the signal and using it in a Kalman filter structure. For the photoplethysmography signals, with modeling every beat of signal to a Gaussian three or four sum form and with adding self-returned equations for model parameters, a nonlinear signal model is obtained. Then,...