434 research outputs found
A New Concept for Medical Imaging Centered on Cellular Phone Technology
According to World Health Organization reports, some three quarters of the world population does not have access to medical imaging. In addition, in developing countries over 50% of medical equipment that is available is not being used because it is too sophisticated or in disrepair or because the health personnel are not trained to use it. The goal of this study is to introduce and demonstrate the feasibility of a new concept in medical imaging that is centered on cellular phone technology and which may provide a solution to medical imaging in underserved areas. The new system replaces the conventional stand-alone medical imaging device with a new medical imaging system made of two independent components connected through cellular phone technology. The independent units are: a) a data acquisition device (DAD) at a remote patient site that is simple, with limited controls and no image display capability and b) an advanced image reconstruction and hardware control multiserver unit at a central site. The cellular phone technology transmits unprocessed raw data from the patient site DAD and receives and displays the processed image from the central site. (This is different from conventional telemedicine where the image reconstruction and control is at the patient site and telecommunication is used to transmit processed images from the patient site). The primary goal of this study is to demonstrate that the cellular phone technology can function in the proposed mode. The feasibility of the concept is demonstrated using a new frequency division multiplexing electrical impedance tomography system, which we have developed for dynamic medical imaging, as the medical imaging modality. The system is used to image through a cellular phone a simulation of breast cancer tumors in a medical imaging diagnostic mode and to image minimally invasive tissue ablation with irreversible electroporation in a medical imaging interventional mode
Tumor location on electroporation therapies by means of multi-electrode structures and machine learning
Electroporation is a phenomenon produced in the cell membrane when it is exposed to high pulsed electric fields that increases its permeability. Among other application fields, this phenomenon can be exploited in a clinical environment for tumor ablation therapies. In this context to achieve optimum results, it is convenient to focus the treatment on the tumor tissue to minimize side effects. In this work, a pre-treatment tumor location method is developed, with the purpose of being able to precisely target the therapy. This is done by taking different impedance measurements with a multi-output electroporation generator in conjunction with a multi-electrode structure. Data are processed by means of a vector of independent artificial neural networks, trained and tested with simulation data, and validated with phantom gels. This algorithm proved to provide suitable accuracy in spite of the low electrode count compared to the number of electrodes of a standard electrical impedance tomography device
Frequency-Division Multiplexing for Electrical Impedance Tomography in Biomedical Applications
Electrical impedance tomography (EIT) produces an image of the electrical impedance distribution of
tissues in the body, using electrodes that are placed on the periphery of the imaged area. These
electrodes inject currents and measure voltages and from these data, the impedance can be
computed. Traditional EIT systems usually inject current patterns in a serial manner which means
that the impedance is computed from data collected at slightly different times. It is usually also a time-consuming process. In this paper, we propose a method for collecting data concurrently from all of the
current patterns in biomedical applications of EIT. This is achieved by injecting current through all of
the current injecting electrodes simultaneously, and measuring all of the resulting voltages at once.
The signals from various current injecting electrodes are separated by injecting different frequencies
through each electrode. This is called frequency-division multiplexing (FDM). At the voltage
measurement electrodes, the voltage related to each current injecting electrode is isolated by using
Fourier decomposition. In biomedical applications, using different frequencies has important
implications due to dispersions as the tissue's electrical properties change with
frequency. Another significant issue arises when we are recording data in a dynamic environment
where the properties change very fast. This method allows simultaneous measurements of all the
current patterns, which may be important in applications where the tissue changes occur in the same
time scale as the measurement. We discuss the FDM EIT method from the biomedical point of view
and show results obtained with a simple experimental system
Diffusion-Weighted MRI for Verification of Electroporation-Based Treatments
Clinical electroporation (EP) is a rapidly advancing treatment modality that uses electric pulses to introduce drugs or genes into, e.g., cancer cells. The indication of successful EP is an instant plasma membrane permeabilization in the treated tissue. A noninvasive means of monitoring such a tissue reaction represents a great clinical benefit since, in case of target miss, retreatment can be performed immediately. We propose diffusion-weighted magnetic resonance imaging (DW-MRI) as a method to monitor EP tissue, using the concept of the apparent diffusion coefficient (ADC). We hypothesize that the plasma membrane permeabilization induced by EP changes the ADC, suggesting that DW-MRI constitutes a noninvasive and quick means of EP verification. In this study we performed in vivo EP in rat brains, followed by DW-MRI using a clinical MRI scanner. We found a pulse amplitude–dependent increase in the ADC following EP, indicating that (1) DW-MRI is sensitive to the EP-induced changes and (2) the observed changes in ADC are indeed due to the applied electric field
DEVELOPMENT OF A XENOGRAFT FOR ANNULAR REPAIR USING PULSED ELECTRIC FIELD EXPOSURES FOR ENHANCED DECELLULARIZATION
Severe back injuries and chronic pain necessitate surgical replacement of damaged intervertebral disc (IVD) cartilage in advanced disease stages. Bovine IVD tissue has been exposed to an upper threshold pulsed electric field (PEF) dose, causing cell death without thermal damage to the tissue. Subsequent PEF exposures at lower magnitudes have accelerated the removal of immunogenic biomolecules though electrokinetic extraction using optimized aqueous solutions. This approach yields a natural scaffold, ready for biocompatibility and mechanical strength assessment. The effects of microsecond pulsed electric fields (µsPEF) on primary bovine AF fibroblast-like cells have been characterized in vitro. PEFs of 10 and 100 µs durations, with varying numbers of pulses and electric field strengths, were applied to the cells. Furthermore, a low-intensity and minimally heating PEF-induced electrokinetic flow for molecular extraction has been established, involving the determination of the electrophoretic mobility of charged molecules within the AF cartilage tissue. Ultimately, a biocompatible AF scaffold has been generated using PEF and electrolyte solutions in a custom-designed bioreactor. Compared to chemical methods that take days, PEF application achieves decellularization of cartilage tissue within three hours, while preserving the desired biomolecules and ultrastructure of the tissue matrix
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