The Experts below are selected from a list of 105 Experts worldwide ranked by ideXlab platform
Periannan Kuppusamy - One of the best experts on this subject based on the ideXlab platform.
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electron paramagnetic resonance oxygen mapping eprom direct visualization of oxygen Concentration in Tissue
Magnetic Resonance in Medicine, 2000Co-Authors: Sendhil S Velan, Richard G Spencer, Jay L Zweier, Periannan KuppusamyAbstract:Tissue oxygen content is a central parameter in physiology but is difficult to measure. We report a novel procedure for spatial mapping of oxygen by electron paramagnetic resonance (EPR) utilizing a spectral-spatial imaging data set, in which an EPR spectrum is obtained from each image volume element. From this data set, spatial maps corresponding to local spin density and maximum EPR spectral line amplitude are generated. A map of local EPR spectral linewidth is then computed. Because linewidth directly correlates with oxygen Concentration, the linewidth image provides a map of oxygenation. This method avoids a difficulty inherent in other oxygen content mapping techniques using EPR, that is, the unwanted influence of local spin probe density on the image. We provide simulation results and data from phantom studies demonstrating the validity of this method. We then apply the method to map oxygen content in rat tail Tissue and vasculature. This method provides a new, widely applicable, approach to direct visualization of oxygen Concentration in living Tissue. Magn Reson Med 43: 804 ‐ 809, 2000. © 2000 Wiley-Liss, inc.
Carey E Floyd - One of the best experts on this subject based on the ideXlab platform.
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Non-invasive Estimation of Potassium (39K) in Bovine Liver Using Neutron Stimulated Emission Computed Tomography (NSECT)
2006 IEEE Nuclear Science Symposium Conference Record, 2006Co-Authors: Anuj J Kapadia, Amy C. Sharma, Georgia D. Tourassi, Janelle E. Bender, Alexander S. Crowell, Matthew R. Kiser, Calvin R. Howell, Carey E FloydAbstract:Neutron stimulated emission computed tomography (NSECT) is being developed as a non-invasive technique to measure element Concentration in in-vivo Tissue at molecular levels. We have developed a system that performs this task using an incident neutron beam that scatters inelastically with an atomic nucleus causing it to emit a characteristic gamma photon. An energy-sensitive gamma detector is used to detect this energy and identify the target atom. Here we describe an experiment to determine the Concentration of natural potassium (39K) in bovine liver without the need for a biopsy. A 5 MeV neutron beam was used to scan a known quantity of bovine liver to obtain a gamma spectrum showing element Concentration in the liver. An aqueous KCl solution calibration sample was then scanned to establish a ratio of potassium Concentration to gamma counts for the experimental setup. Counts from gamma peaks corresponding to excited states in 39K were summed and compared with counts from the known calibration sample, to give the Concentration of 39K in the liver. A high purity germanium (HPGe) clover detector was used to measure the emitted gamma energy. The results were validated through neutron activation analysis (NAA) of the liver sample. The Concentration of 39K reported by NSECT was found to be within 13% of the NAA result, clearly demonstrating the ability of NSECT for non-invasive quantification of element Concentration in Tissue.
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an attenuation correction technique to correct for neutron and gamma attenuation in the reconstructed image of a neutron stimulated emission computed tomography nsect system
Medical Imaging 2005: Physics of Medical Imaging, 2005Co-Authors: Anuj J Kapadia, Carey E FloydAbstract:Neutron spectroscopy is being developed as a tomographic tool to measure trace element Concentration in the body at molecular levels. We are developing a neutron stimulated emission computed tomography (NSECT) system using inelastic scattering of neutrons by target nuclei, to identify elements and their Concentration in Tissue. An incoming neutron scatters inelastically with an atomic nucleus, which emits a gamma photon of specific energy. This energy, which is detected by an energy-sensitive Gamma detector, is characteristic of the scattering nucleus. The neutron beam and gamma photons undergo considerable attenuation while passing through the body, causing a reduction in detected counts leading to inaccurate reconstruction. We describe a technique to correct for this attenuation as follows. The scanning geometry used for data acquisition is simulated. The lengths of attenuating material lying in the path of the neutron beam are calculated. Neutron attenuation is determined along this path, using attenuation coefficients for each element. Gamma attenuation is calculated similarly for the path between the point of gamma origin and the detector. A transmission profile is then determined for each projection, using the product of the neutron and gamma attenuations for every point along the projection. The inverse of the integral of this profile yields a correction factor. The experimental data is multiplied by the correction factors to yield attenuation corrected projections. After correction, the projection data is seen to represent the known elemental distribution more accurately. This correction technique improves the consistency of the projections, and leads to the improved accuracy in reconstructed NSECT images.
Ofer Barnea - One of the best experts on this subject based on the ideXlab platform.
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Blood Flow Versus Hematocrit in Optimization of Oxygen Transfer to Tissue During Fluid Resuscitation
Cardiovascular Engineering and Technology, 2015Co-Authors: Jamal Siam, Marwa Kadan, Ron Flaishon, Ofer BarneaAbstract:The effectiveness of fluid resuscitation regimens in hemorrhagic trauma is assessed based on its ability to increase oxygen Concentration in Tissue. Fluid resuscitation using both crystalloids and colloids fluids, creates a dilemma due to its opposing effects on oxygen transfer. It increases blood flow thereby augmenting oxygen transport but it also dilutes the blood simultaneously and reduces oxygen Concentration thereby reducing oxygen transport. in this work we have studied these two opposing effects of fluid therapy on oxygen delivery to Tissue. A mathematical model of oxygen diffusion from capillaries to Tissue and its distribution in Tissue was developed and integrated into a previously developed hemodynamic model. The capillary-Tissue model was based on the Krogh structure. Compared to other models, fewer simplifying assumptions were made leading to different boundary conditions and less constraints, especially regarding capillary oxygen content at its venous end. Results showed that oxygen content in blood is the dominant factor in oxygen transport to Tissue and its effect is greater than the effect of flow. The integration of the capillary/Tissue model with the hemodynamic model that links administered fluids with flow and blood dilution indicated that fluid resuscitation may reduce oxygen transport to Tissue.
Sendhil S Velan - One of the best experts on this subject based on the ideXlab platform.
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electron paramagnetic resonance oxygen mapping eprom direct visualization of oxygen Concentration in Tissue
Magnetic Resonance in Medicine, 2000Co-Authors: Sendhil S Velan, Richard G Spencer, Jay L Zweier, Periannan KuppusamyAbstract:Tissue oxygen content is a central parameter in physiology but is difficult to measure. We report a novel procedure for spatial mapping of oxygen by electron paramagnetic resonance (EPR) utilizing a spectral-spatial imaging data set, in which an EPR spectrum is obtained from each image volume element. From this data set, spatial maps corresponding to local spin density and maximum EPR spectral line amplitude are generated. A map of local EPR spectral linewidth is then computed. Because linewidth directly correlates with oxygen Concentration, the linewidth image provides a map of oxygenation. This method avoids a difficulty inherent in other oxygen content mapping techniques using EPR, that is, the unwanted influence of local spin probe density on the image. We provide simulation results and data from phantom studies demonstrating the validity of this method. We then apply the method to map oxygen content in rat tail Tissue and vasculature. This method provides a new, widely applicable, approach to direct visualization of oxygen Concentration in living Tissue. Magn Reson Med 43: 804 ‐ 809, 2000. © 2000 Wiley-Liss, inc.
Athanassios Sambanis - One of the best experts on this subject based on the ideXlab platform.
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dual perfluorocarbon method to noninvasively monitor dissolved oxygen Concentration in Tissue engineered constructs in vitro and in vivo
Biotechnology Progress, 2011Co-Authors: Robert C Long, Nicholas E Simpson, Athanassios SambanisAbstract:Noninvasive in vivo monitoring of Tissue implants provides important correlations between construct function and the observed physiologic effects. As oxygen is a key parameter affecting cell and Tissue function, we established a monitoring method that utilizes 19F nuclear magnetic resonance (NMR) spectroscopy, with perfluorocarbons (PFCs) as oxygen Concentration markers, to noninvasively monitor dissolved oxygen Concentration (DO) in Tissue engineered implants. Specifically, we developed a dual PFC method capable of simultaneously measuring DO within a Tissue construct and its surrounding environment, as the latter varies among animals and with physiologic conditions. in vitro studies using an NMR-compatible bioreactor demonstrated the feasibility of this method to monitor the DO within alginate beads containing metabolically active murine insulinoma βTC-tet cells, relative to the DO in the culture medium, under perfusion and static conditions. The DO profiles obtained under static conditions were supported by mathematical simulations of the system. in vivo, the dual PFC method was successful in tracking the oxygenation state of entrapped βTC-tet cells and the surrounding peritoneal DO over 16 days in normal mice. DO measurements correlated well with the extent of cell growth and host cell attachment examined postexplantation. The peritoneal oxygen environment was found to be variable and hypoxic, and significantly lower in the presence of metabolically active cells. The significance of the dual PFC system in providing critical DO measurements for entrapped cells and other Tissue constructs, in vitro and in vivo, is discussed. © 2011 American institute of Chemical Engineers Biotechnol. Prog., 2011