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In this paper we provide a quantitative electroencephalogram (EEG) analysis to study the effect of hypothermia on the neurological recovery of brain after cardiac arrest. We hypothesize that the brain injury results in a reduction in information of the brain rhythm. To measure the information content of the EEG a new measure called information quantity (IQ), which is the Shannon entropy of decorrelated...
QT dispersion (QTD) is thought to represent the regional nonuniformity of ventricular repolarization and can serve as a prognostic marker for vulnerability to ventricular arrhythmias and risk for sudden cardiac death (SCD). In this study, we used an in vivo swine model to investigate the change of QT-peak dispersion before and after the introduction of a left-ventricular (LV) free-wall structural...
Thermography captures the temperature distribution of the human skin and is employed in various medical applications. Often it is useful to cross-reference the resulting thermograms with visual images of the patient, either to see which part of the anatomy is affected by a certain disease or to judge the efficacy of the treatment. An attractive approach to provide this information is to overlay the...
A 3-dimensional hemispheric computational brain model is developed to simulate infusion of cold saline in the carotid arteries in terms of brain cooling for stroke therapy. The model is based on the Pennes bioheat equation, with four tissue layers: white matter, gray matter, skull, and scalp. The stroke lesion is simulated by reducing blood flow to a selected volume of the brain by a factor of one-third,...
Concerns have been expressed about safety of MRI examination of two groups of people, namely pregnant mothers and cardiac pacemaker bearers. The main uncertainty relates to excessive heating by pulsed radio frequency (RF) fields. To address these issues, numerical evaluations of the power deposition are performed for a 27-week old fetus in a simplified model of the mother, and a realistic model of...
Previously, we introduced a new harmonic motion imaging (HMI) technique for simultaneous monitoring and generation of ultrasound therapy treatment using a single element focused-ultrasound and one pulse-echo transducer. The new HMI technique uses an amplitude-modulated beam (instead of using two beams) that has a stable focal zone for the applied harmonic radiation force. The harmonic radiation force...
As the thermoregulation centres are deep in the brain, the cerebral temperature is one of the most important markers of fever, circadian rhythms physical and mental activities. However due to a lack of accessibility, the brain temperature is not easily measured. The axillary, buccal, tympanic and rectal temperatures do not reflect exactly the cerebral temperature. Nevertheless the rectal temperature...
The temperature recovering curve derived by cold stimulation experiment reveals human inner metabolism status. The errors of the measured data should be eliminated. A Tikhonov regularization method is used in this study to regularize the original data. The results present that the ability of body metabolic function can be measured by the temperature derivative curve, especially the characteristics...
The role and the potentialities of high-resolution infrared thermography, combined to bio-heat modelling, have been largely described in the last years in a wide variety of biomedical applications. Quantitative assessment over time of the cutaneous temperature and/or of other biomedical parameters related to the temperature (e.g., cutaneous blood flow, thermal inertia, sympathetic skin response) allows...
Long-term, low duty cycle monitoring of patients with a variety of disabilities or health concerns is often required. In this paper, we discuss the design considerations and implementation of an ultra-low power wireless medical sensor platform, suitable for a wide range of medical and sports applications. A hardware demonstration prototype based on readily available components is presented with sensors...
The radio frequency field used in magnetic resonance imaging (MRI) procedures leads to temperature and local absorption rate (SAR) increase for patients with implanted pacemakers (PM). In this work a methodological approach for temperature and SAR measurements using fluoroptic probes is presented. Experimental measures show how the position of temperature probes affects the temperature and SAR value...
To study calcium mediated arrhythmogenesis, we have developed a multi-modal optical mapping system that is able to perform dual calcium voltage and ratiometric calcium optical mapping in the same cardiac preparation. To ensure physiological stability of the preparation, the ECG, coronary pressure, coronary flow, and perfusion temperature are continuously monitored throughout each experiment. The multi-modal...
A finite element (FE) simulation of the thermoelastic laser generated surface waves in a 3-layered model of human skin is presented. Commercial finite element code ANSYS is used to study the effects of changing laser wavelength and hence the optical absorption has on the generated surface waves. The FE model consists of a thermal analysis with a volumetric heat generation boundary condition to simulate...
Aim of this study is the improvement of the focusing properties of a microwave radiometry tomography system, used for the imaging of the product of temperature and conductivity in biological tissues via contactless measurements. The operation principle of the device in question is based on an ellipsoidal conductive wall cavity, which provides the required beamforming and focusing. The biological tissue...
Adults with obstructive sleep apnea syndrome (OSAS) are known to have impaired autonomic function but the corresponding effects in children appear to be more subtle. Model-based analysis of the cardiovascular response to cold face test (CFT) was used to quantify daytime autonomic dysfunction. The increase in transfer gain between respiration and RRI was not different between controls and OSAS. However,...
There is a growing interest in the use of chronic deep brain stimulation (DBS) for the treatment of medically refractory movement disorders and other neurological and psychiatric conditions. Fundamental questions remain about the physiologic effects and safety of DBS. Previous basic research studies have focused on the direct polarization of neuronal membranes by electrical stimulation. The goal of...
The objective of this research is to develop noninvasive techniques to determine thermal properties of layered biologic structures based on measurements from the surface. The self-heated thermistor technique is evaluated both numerically and experimentally. The finite element analyses, which confirm the experimental results, are used to study the temperature profiles occurring in the thermistor-tissue...
The livestock industry is an integral part of the United States economy. The continued production of quality beef requires new and improved methods for long term monitoring of animal health. Additional benefits can be realized from this class of technology, such as the ability to identify the presence of disease early and thereby prevent its spread. An important element of health assessment is the...
One requirement of a chronically implantable, wireless neural interface device is the integration of electronic circuitry with the microelectrode array. Since the electronic IC dissipates a certain amount of power, it will affect the temperature in the tissues surrounding the implant site. In this paper, the thermal influence of an integrated, 3-dimensional Utah electrode array, to be implanted in...
Biomedical protocols based on thermal infrared images often require effective image registration. Algorithms specifically designed for registration of thermal images are hardly available and use of algorithms designed for other imaging techniques may result poorly reliable. In fact, registration algorithms developed for other biomedical images often require rigid-body assumption or limited range for...
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