Diagnosing and monitoring pleural effusion using parametric electrical impedance tomography - a computational 3D model and preliminary experimental results.

Purpose: Diagnosing and monitoring pleural effusion (PE) is challenging due unsuitability of existing modalities. In the present study, a novel parametric electrical impedance tomography (pEIT) technique, tailored to a clinically feasible system to diagnose PE is presented.

Methods: An electrical impedance tomography (EIT) numeric solver was applied to a 3D realistic normal model and five PE models to simulate sets of surface measurements.

Changes in High-Frequency Intracardiac Electrogram Indicate Cardiac Ischemia.

High-frequency QRS (HFQRS) analysis of surface ECG is a reliable marker of cardiac ischemia (CI). This study aimed to assess the response of HFQRS signals from standard intracardiac electrodes (iHFQRS) to CI in swine and compare them with conventional ST-segment deviations. Devices with three intracardiac leads were implanted in three swine in a controlled environment.

Parametric electrical impedance tomography for measuring bone mineral density in the pelvis using a computational model.

Osteoporosis is defined as bone microstructure deterioration resulting a decrease of bone's strength. Measured bone mineral density (BMD) constitutes the main tool for Osteoporosis diagnosis, management, and defines patient's fracture risk. In the present study, parametric electrical impedance tomography (pEIT) method was examined for monitoring BMD, using a computerized simulation model and preliminary real measurements.

Monitoring brain damage using bioimpedance technique in a 3D numerical model of the head.

Disturbance in the blood supply to the brain causes a stroke or cerebrovascular accident. This can be due to ischemia caused by blockage (thrombosis, arterial embolism) or a hemorrhage. In this study, the feasibility of basic electrical impedance technique for monitoring such damage was analyzed using a computerized model.

Quantifying QRS changes during myocardial ischemia: Insights from high frequency electrocardiography.

Over four decades of high frequency electrocardiography research have provided a body of knowledge about QRS changes during myocardial ischemia, and the techniques to measure and quantify them. High-frequency QRS (HFQRS) components, being closely related to the pattern of ventricular depolarization, carry valuable clinical information. Changes in HFQRS amplitude and morphology have been shown to be sensitive diagnostic markers of myocardial ischemia, often superior to measures of ST-T segment changes.

Assessment of cardiac stroke volume in patients with implanted cardiac pacemaker using parametric electrical impedance tomography: a theoretical 2D study.

The present theoretical study examines the ability to estimate cardiac stroke volume (CSV) in patients with implanted cardiac pacemaker using parametric electrical impedance tomography (pEIT) in a 2D computerized model of the thorax. CSV is a direct indicator of the cardiac pumping efficiency. The commonly used methods for measuring CSV require the invasive procedure of right heart catheterization or use expensive imaging techniques (i.

High-frequency QRS analysis in patients with acute myocardial infarction: a preliminary study.

Background: The 12-lead electrocardiogram (ECG) is a primary tool in the evaluation and risk stratification of patients with suspected acute myocardial infarction (AMI), even though the initial ECG of these patients is often normal or nondiagnostic. Myocardial ischemia induces depolarization changes that can be quantified by analysis of high-frequency QRS (HFQRS) components. We aimed to demonstrate the potential usefulness of HFQRS analysis in diagnosing myocardial ischemia by characterizing the morphological patterns of the HFQRS signals in patients with AMI before and following reperfusion.

Bioimpedance technique for monitoring cerebral artery stenosis in a 3D numerical model of the head.

Insufficient blood supply to the brain causes a transient ischemic attack (TIA) or a stroke. One of the causes to insufficient blood supply is cerebral artery stenosis. In this study, the feasibility of bioimpedance for monitoring such stenosis was analyzed.

Estimating pulmonary congestion in elderly patients using bio-impedance technique: correlation with clinical examination and X-ray results.

The bio-impedance technique provides a safe, low-cost and non-invasive alternative for lung fluid level monitoring. Here we have investigated the feasibility of a novel bio-impedance system in measuring pulmonary congestion in elderly patients suffering from congestive heart failure (CHF). The system employed a parametric reconstruction algorithm to assess mean lung resistivity.

Detection of stress-induced myocardial ischemia from the depolarization phase of the cardiac cycle--a preliminary study.

Background: Electrocardiogram (ECG)-based detection of ischemia is typically dependent on identifying changes in repolarization. Analysis of high-frequency QRS (HFQRS) components, related to the depolarization phase of the cardiac action potential, has been reported to better identify ischemia. Our aim was to test the hypothesis that HFQRS analysis is both more sensitive and specific than standard ECG for detecting exercise-induced ischemia in patients undergoing exercise myocardial perfusion imaging (MPI).

A novel telemedicine system for monitoring congestive heart failure patients.

Congestive heart failure is a widespread cardiac disease in western countries. At present, the main measure for monitoring the level of pulmonary edema in telemedicine systems is weight, which is not a reliable indicator. The authors propose a novel bioimpedance telemedical system to monitor these patients.

High-frequency QRS electrocardiogram analysis during exercise stress testing for detecting ischemia.

Introduction: ECG stress testing is an inexpensive and non-invasive detector of myocardial ischemia; addition of high-frequency QRS analysis (HFQRS) may improve accuracy. This study compared HFQRS during exercise in patients with and without ischemia as defined by multiple criteria.

Material And Methods: High-resolution ECGs were recorded for 139 patients undergoing T99-sestamibi/T201-thallium stress testing.

Induced current bio-impedance technique for monitoring bone mineral density--a simulation model.

In this study, the feasibility of using induced current bio-impedance technique as a method to determine and monitor bone mineral density (BMD) was theoretically evaluated using computerized simulation model. A 2D polar coordinates numerical solver was developed using the Finite Volume Method (FVM) in order to simulate the developed potentials over an axial CT cross section of a human thigh. Varying femur BMD were simulated by varying femur relative permittivity values.

Monitoring lung resistivity changes in congestive heart failure patients using the bioimpedance technique.

The feasibility of a novel, dedicated system for monitoring lung resistivity in congestive heart failure patients, implementing a hybrid approach of the bioimpedance technique, was assessed in this preliminary study. Thirty-three healthy volunteers and 34 congestive heart failure patients were measured with the PulmoTrace system (CardioInspect, Tel Aviv University, Tel Aviv, Israel) during tidal respiration, and the ability to monitor the respective lung resistivity values was assessed. Mean left and right lung resistivity values of 1205+/-163 and 1200+/-165 ohm.

Induced current bio-impedance technique for monitoring cryosurgery procedure in a two-dimensional head model using generalized coordinate systems.

In the noninvasive bio-impedance technique, small amplitude currents are applied to the body and the developing potentials on its surface are measured. This noninvasive technique is used to monitor physiological and pathological processes, which alter the values or the spatial distribution of the electrical impedance inside the human body. A possible application of the bio-impedance technique is monitoring brain cryosurgery procedure--a surgical technique that employs freezing to destroy undesirable tissues.

Contactless bio-impedance monitoring technique for brain cryosurgery in a 3D head model.

A contactless induced-current bio-impedance system for monitoring brain cryosurgery procedure was modeled and numerically simulated, where the excitation coil was also performing as the measuring, or pick-up coil. A segmented three-dimensional (3D) MRI database was used for building the volume conductor geometry, and the numerical finite-volume method was employed for solving the forward problem for calculating the scalar potential distribution and the second-order voltage change on the pick-up coil. Several coil configurations were considered, varying in their relative positioning to the 3D head model.

Model-based prediction of expiratory resistance index in patients with asthma.

Objectives: Develop a sensitive algorithm and index for detection of asthma patients using forced expiratory flow curves.

Methods: A lumped-parameter model of forced expiration was developed. The model can predict the flow-volume curve during forced expiratory maneuver.

Automatic identification of bacterial types using statistical imaging methods.

The objective of the current study is to develop an automatic tool to identify microbiological data types using computer-vision and statistical modeling techniques. Bacteriophage (phage) typing methods are used to identify and extract representative profiles of bacterial types out of species such as the Staphylococcus aureus. Current systems rely on the subjective reading of profiles by a human expert.

Induced current electrical impedance tomography system: experimental results and numerical simulations.

In electrical impedance tomography (EIT), measurements of developed surface potentials due to applied currents are used for the reconstruction of the conductivity distribution. Practical implementation of EIT systems is known to be problematic due to the high sensitivity to noise of such systems, leading to a poor imaging quality. In the present study, the performance of an induced current EIT (ICEIT) system, where eddy current is applied using magnetic induction, was studied by comparing the voltage measurements to simulated data, and examining the imaging quality with respect to simulated reconstructions for several phantom configurations.

Validation of vital signs recorded via a new telecare system.

A telecare system (Medic4All) has been developed that relies on a wireless wristwatch-like sensor to measure the pulse wave from the radial artery. From this, the heart rate and respiration rate are derived. The system's performance was examined by comparing the results obtained from the pulse wave signal with those obtained from conventional electrocardiographic and spirometer devices.

Induced-current electrical impedance tomography: a 2-D theoretical simulation.

A reconstruction algorithm, based on the modified Newton-Raphson algorithm, was developed for induced-current electrical impedance tomography and studied in theoretical two-dimensional geometry representing a human thorax. The finite-volume method was applied for the discretization of the physical domain, resulting in a symbolic representation of the Jacobian matrix, which is accurate and fast to construct. Several system configurations, differing in the number of excitation coils and electrodes, were simulated, and the performance in thoracic imaging was studied.

A three-dimensional numerical fluid dynamic model of antigen-antibody surface adsorption on piezoelectric immunosensors.

A piezoelectric crystal is a unit that changes its frequency in parallel with a change in its mass. This characteristic is exploited in designing flow cell-based immunosensors for detecting the concentration of antibodies in liquid samples. In the present study, computational fluid dynamic techniques are used to optimize the antigen-antibody binding process on an electrode surface placed on the base of a conical flow cell.