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Koeppe, Robert A., David M. Raffel, Scott E. Snyder, Edward P. Ficaro, Michael R. Kilbourn, and David E. Kuhl. "Dual-[11C]Tracer Single-Acquisition Positron Emission Tomography Studies." Journal of Cerebral Blood Flow & Metabolism 21, no. 12 (December 2001): 1480–92. http://dx.doi.org/10.1097/00004647-200112000-00013.
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The ability to study multiple physiologic processes of the brain simultaneously within the same subject would provide a new means to explore the interactions between neurotransmitter systems in vivo. Currently, examination of two distinct neuropharmacologic measures with positron emission tomography (PET) necessitates performing two separate scans spaced in time to allow for radionuclide decay. The authors present results from a dual-tracer PET study protocol using a single dynamic-scan acquisition where the injections of two tracers are offset by several minutes. Kinetic analysis is used to estimate neuropharmacologic parameters for both tracers simultaneously using a combined compartmental model configuration. This approach results in a large reduction in total study time of nearly 2 hours for carbon-11–labeled tracers. As multiple neuropharmacologic measures are obtained at nearly the same time, interventional protocols involving a pair of dual-tracer scans become feasible in a single PET session. Both computer simulations and actual human PET studies were performed using combinations of three different tracers: [11C]flumazenil, N-[11C]methylpiperidinyl propionate, and [11C]dihydrotetrabenazine. Computer simulations of tracer-injection separations of 10 to 30 minutes showed the feasibility of the approach for separations down to 15 to 20 minutes or less. Dual-tracer PET studies were performed in 32 healthy volunteers using injection separations of 10, 15, or 20 minutes. Model parameter estimates for each tracer were similar to those obtained from previously performed single-injection studies. Voxel-by-voxel parametric images were of good quality for injections spaced by 20 minutes and were nearly as good for 15-minute separations, but were degraded noticeably for some model parameters when injections were spaced by only 10 minutes. The authors conclude that dual-tracer single-scan PET is feasible, yields accurate estimates of multiple neuropharmacologic measures, and can be implemented with a number of different radiotracer pairs.
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Chernokozhev, D. A., K. I. Kuznetsova, R. R. Gazimov, A. S. Zasedatelev, and M. S. Khozyaiov. "MODERN METHODOLOGICAL POSSIBILITIES OF THE TRACER METHOD FOR ASSESSING THE COVERAGE OF AN OIL RESERVOIR BY FLOODING." BULLETIN of Russian Academy of Natural Sciences 21 (April 2021): 24–28. http://dx.doi.org/10.52531/1682-1696-2021-21-1-24-28.
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The article presents the results of modeling tracer studies of the process of flooding of an oil reservoir. As a result of the studies, the dependences on the time of the change in the volume occupied by the injected water were obtained. Formulas are given that allow us to calculate the values of the coefficient of coverage of the reservoir area by flooding as a whole and the contribution of each injection well to flooding. The technology is implemented by continuously pumping the tracer into the injection well. Continuous injection of different tracers into different injection wells allows for operational monitoring of oil field development
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Clemens, Torsten, Markus Lüftenegger, Ajana Laoroongroj, Rainer Kadnar, and Christoph Puls. "The Use of Tracer Data To Determine Polymer-Flooding Effects in a Heterogeneous Reservoir, 8 Torton Horizon Reservoir, Matzen Field, Austria." SPE Reservoir Evaluation & Engineering 19, no. 04 (February 14, 2016): 655–63. http://dx.doi.org/10.2118/174349-pa.
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Summary Polymer-injection pilot projects aim at reducing the uncertainty and risk of full-field polymer-flood implementation. The interpretation of polymer-pilot projects is challenging because of the complexity of the process and fluids moving out of the polymer-pilot area. The interpretation is increasingly more complicated with the heterogeneity of the reservoir. In the polymer pilot performed in the 8 Torton Horizon (TH) reservoir of the Matzen field in Austria, a polymer-injection well surrounded by a number of production wells was selected. A tracer was injected 1 week before polymer injection. The tracer showed that the flow field in the reservoir was dramatically modified with increasing amounts of polymer injected. Despite short breakthrough times of 4 to 10 weeks observed for the tracer, polymer breakthrough occurred only after more than 12 months although injection and production rates were not substantially changed. The tracer signal indicated that the reservoir is heterogeneous, with high flow velocities occurring along a number of flow paths with a limited volume that are strongly connecting the injection and production wells. By injecting polymers, the mobility of the polymer-augmented water was reduced compared with water injection, and led to flow diversion into adjacent layers. The tracer response showed that the speed of the tracer moving from injection to production wells was reduced with increasing amount of polymer injected. This response was used to assess the changes of the amount of water flowing from the injection well to production wells. After a match for the tracer curve was obtained, adsorption, residual resistance factor (RRF), and dispersivity were calculated. The results showed that, even for heterogeneous reservoirs without good conformance of the pilot, the critical parameters for polymer-injection projects can be assessed by analyzing tracer and polymer response. These parameters are required to determine whether implementation of polymer injection at field scale is economically attractive. Along the flow path that is connecting injection and production well, as shown by the tracer response, an incremental recovery of approximately 8% was achieved. The polymer retention and inaccessible pore volume (IPV) in the reservoir were in the same range as in corefloods. Incremental oil recovery caused by acceleration along the flow path was estimated at approximately 20% of the overall incremental oil production caused by polymer injection and 80% was attributed to improved sweep efficiency.
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Sudo, Shigeru, and Naoki Tamura. "Tracer-encapsulated solid pellet injection system." Review of Scientific Instruments 83, no. 2 (February 2012): 023503. http://dx.doi.org/10.1063/1.3681447.
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Wang, Sheng-Ping, Dan Zhou, Zuliang Yao, Santhosh Satapati, Ying Chen, Natalie A. Daurio, Aleksandr Petrov, et al. "Quantifying rates of glucose production in vivo following an intraperitoneal tracer bolus." American Journal of Physiology-Endocrinology and Metabolism 311, no. 6 (December 1, 2016): E911—E921. http://dx.doi.org/10.1152/ajpendo.00182.2016.
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Aberrant regulation of glucose production makes a critical contribution to the impaired glycemic control that is observed in type 2 diabetes. Although isotopic tracer methods have proven to be informative in quantifying the magnitude of such alterations, it is presumed that one must rely on venous access to administer glucose tracers which therein presents obstacles for the routine application of tracer methods in rodent models. Since intraperitoneal injections are readily used to deliver glucose challenges and/or dose potential therapeutics, we hypothesized that this route could also be used to administer a glucose tracer. The ability to then reliably estimate glucose flux would require attention toward setting a schedule for collecting samples and choosing a distribution volume. For example, glucose production can be calculated by multiplying the fractional turnover rate by the pool size. We have taken a step-wise approach to examine the potential of using an intraperitoneal tracer administration in rat and mouse models. First, we compared the kinetics of [U-13C]glucose following either an intravenous or an intraperitoneal injection. Second, we tested whether the intraperitoneal method could detect a pharmacological manipulation of glucose production. Finally, we contrasted a potential application of the intraperitoneal method against the glucose-insulin clamp. We conclude that it is possible to 1) quantify glucose production using an intraperitoneal injection of tracer and 2) derive a “glucose production index” by coupling estimates of basal glucose production with measurements of fasting insulin concentration; this yields a proxy for clamp-derived assessments of insulin sensitivity of endogenous production.
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Joshi, Aniket D., Robert A. Koeppe, Jeffrey A. Fessier, and Michael R. Kilbourn. "Signal Separation and Parameter Estimation in Noninvasive Dual-Tracer PET Scans using Reference-Region Approaches." Journal of Cerebral Blood Flow & Metabolism 29, no. 7 (April 29, 2009): 1346–57. http://dx.doi.org/10.1038/jcbfm.2009.53.
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This is the first study to report results from a noninvasive dual-tracer positron emission tomography (PET) in humans not requiring arterial sampling, in which two radiotracers were injected closely in time within the same scan. These studies yield near simultaneous information on two different neuropharmacological systems, providing better characterization of a subject's neurologic condition. The noninvasive dual-tracer approach described in this study is based on the primary assumption that an appropriate bolus plus constant infusion protocol brings the reference tissue of the first radiotracer to steady state before injection of the second tracer. Two methods for separation of time-activity curves (TACs) and parameter estimation were investigated, namely (1) an extrapolation method, in which TACs of the first tracer were extrapolated over total scan duration followed by subtraction from dual-tracer TACs and (2) a simultaneous fitting method, in which reference-region models for both tracers were fitted simultaneously to dual-tracer TACs. Combinations of two reversible tracers ([11C]flumazenil and [11C]dihydrotetrabenazine) or one reversible and one irreversible tracer ([11C] N-methylpiperidinyl propionate) were used. After the dual-tracer scan, a single-tracer (ST) scan using one of the tracers was obtained for comparison of the dual-tracer results. Both approaches provided parameter estimates with intersubject regions-of-interest means typically within 10% of those obtained from ST scans without an appreciable increase in variance.
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Akanji, Lateef, and Gabriel Falade. "Closed-Form Solution of Radial Transport of Tracers in Porous Media Influenced by Linear Drift." Energies 12, no. 1 (December 22, 2018): 29. http://dx.doi.org/10.3390/en12010029.
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A new closed-form analytical solution to the radial transport of tracers in porous media under the influence of linear drift is presented. Specifically, the transport of tracers under convection–diffusion-dominated flow is considered. First, the radial transport equation was cast in the form of the Whittaker equation by defining a set of transformation relations. Then, linear drift was incorporated by considering a coordinate-independent scalar velocity field within the porous medium. A special case of low-intensity tracer injection where molecular diffusion controls tracer propagation but convection with linear velocity drift plays a significant role was presented and solved in Laplace space. Furthermore, a weak-form numerical solution of the nonlinear problem was obtained and used to analyse tracer concentration behaviour in a porous medium, where drift effects predominate and influence the flow pattern. Application in enhanced oil recovery (EOR) processes where linear drift may interfere with the flow path was also evaluated within the solution to obtain concentration profiles for different injection models. The results of the analyses indicated that the effect of linear drift on the tracer concentration profile is dependent on system heterogeneity and progressively becomes more pronounced at later times. This new solution demonstrates the necessity to consider the impact of drift on the transport of tracers, as arrival times may be significantly influenced by drift intensity.
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Petrič, Metka, Nataša Ravbar, Petra Gostinčar, Petra Krsnik, and Marina Gacin. "Establishment of a freely accessible GIS database containing the results of groundwater tracing and possibilities of its use." Geologija 63, no. 2 (December 7, 2020): 203–20. http://dx.doi.org/10.5474/geologija.2020.017.
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Tracing with artificial tracers is a research method that gives very good results in examining the direction and characteristics of groundwater flow in karst aquifers. The first mention of such experiments in Slovenian karst dates back to history and the beginnings of their use in the water resources management process in the first years of the 20th century. From that point on, more than two hundred tracer tests were carried out in Slovenian karst. Unfortunately, their results often remain hidden in internal reports in the archives of implementing organisations and are very difficult to access. The search for published results is also a time-consuming process, despite the possibilities of the use of search engines and key words. Due to the need for a systematic and rapidly accessible digital inventory of the tracer tests results, such inventory was designed and is now freely accessible in the Environmental Atlas (Atlas okolja), the spatial information system of Slovenian Environment Agency. In the database the results of 231 available tracer tests have been assembled, arranged and georeferenced. The article describes the data set concept, the process of collecting, verifying and evaluating data and the method of their transformation into a GIS database. Two points layers (injection site and sampling site) and one line layer (linear connection between both sites) were created. Symbology of line layer varies with different type of connection between injection and sampling site. By clicking on an individual element, selected data on the tracer test are displayed, and most of them are also accompanied by a copy of the data source (articles, reports). In this way it is possible to obtain more detailed information about the tracer test and its results. The database also provides a possibility of various comparative analyses. The article shows results of some of the basic statistical analyses in which the purpose and implementation of tracer tests, used tracers, characteristics of injection and sampling sites, and characteristics and velocities of groundwater flow connections were compared. It also provides an overview of the results of the tracer tests carried out within individual groundwater bodies. On the basis of the status identified, the locations for new tracer tests are proposed.
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Seki, Chie, Jeff Kershaw, Paule-Joanne Toussaint, Kenichi Kashikura, Tetsuya Matsuura, Hideaki Fujita, and Iwao Kanno. "15O Radioactivity Clearance is Faster after Intracarotid Bolus Injection of 15O-Labeled Oxyhemoglobin than after 15O-Water Injection." Journal of Cerebral Blood Flow & Metabolism 23, no. 7 (July 2003): 838–44. http://dx.doi.org/10.1097/01.wcb.0000071889.63724.1f.
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The authors tested the hypothesis that the oxygen content of brain tissue is negligible by injecting an intracarotid bolus of 15O-labeled tracer into rats. Under the hypothesis, the clearance rates of 15O radioactivity from the brain after injections of both 15O-labeled water (H215O) and 15O-labeled oxyhemoglobin (HbO15O) should be identical. However, the logarithmic slope of the 15O radioactivity curve after HbO15O injection (0.494 ± 0.071 min-1) was steeper than that after H215O injection (0.406 ± 0.038 min−1) ( P<0.001, n = 13), where the time range used in the comparison was between 60 and 120 seconds after the injection. A possible interpretation of this result is that nonmetabolized O15O may dwell in the brain tissue for a finite period of time before it is eventually metabolized or returned to the blood stream unaltered. These findings contradict assumptions made by models currently used to measure cerebral oxygen metabolism.
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Loula, A. F. D., J. N. C. Guerreiro, F. L. B. Ribeiro, and L. Landau. "Tracer Injection Simulations by Finite Element Methods." SPE Advanced Technology Series 4, no. 01 (May 1, 1996): 150–56. http://dx.doi.org/10.2118/27047-pa.
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Horikoshi, Toru, Yasuhiro Asari, Arata Watanabe, Mikito Uchida, Takako Umeda, Hidehito Koizumi, and Hiroyuki Kinouchi. "Unsuccessful tracer injection in radionuclide cisternography revisited." Annals of Nuclear Medicine 20, no. 4 (May 2006): 333–36. http://dx.doi.org/10.1007/bf02984653.
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Tuvdendorj, Demidmaa, David L. Chinkes, David N. Herndon, Xiao-Jun Zhang, and Robert R. Wolfe. "A novel stable isotope tracer method to measure muscle protein fractional breakdown rate during a physiological non-steady-state condition." American Journal of Physiology-Endocrinology and Metabolism 304, no. 6 (March 15, 2013): E623—E630. http://dx.doi.org/10.1152/ajpendo.00552.2012.
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The measurement of the fractional breakdown rate (FBR) of muscle proteins during physiological non-steady state of amino acids (AAs) presents some challenges. Therefore, the goal of the present experiment was to modify the bolus stable isotope tracer injection approach to determine both fractional synthesis rate (FSR) and FBR of leg muscle protein during a physiological non-steady state of AAs. The approach uses the traditional precursor-product principle but is modified with the assumption that inward transport of AAs is proportional to their plasma concentrations. The FBR value calculated from the threonine tracer served as a reference to evaluate the validity of the FBR measurement from the phenylalanine tracer, which was under a non-steady-state condition due to the concomitant injection of unlabeled phenylalanine. Plasma phenylalanine concentration increased more than fourfold after the bolus injection, and thereafter it decreased exponentially, whereas the threonine concentration remained stable. FBR values were similar with the two tracers [0.133 ± 0.003 and 0.148 ± 0.003%/h (means ± SE) for the phenylalanine and threonine tracers, respectively, P > 0.05]. In addition, FSR values for the two tracers were similar (0.069 ± 0.002 and 0.067 ± 0.001%/h for the phenylalanine and threonine tracers, respectively, P > 0.05), indicating that the traditional FSR approach can also be used in the non-steady state. Accordingly, net balance (NB) values were similar (−0.065 ± 0.002 and −0.081 ± 0.002%/h for the phenylalanine and threonine tracers, respectively, P > 0.05). This new method of measuring muscle protein FBR during physiological non-steady state gives reliable results and allows simultaneous measurement of muscle protein FSR and thus a calculation of NB.
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Werder, Mauro A., Alexandre Loye, and Martin Funk. "Dye tracing a jökulhlaup: I. Subglacial water transit speed and water-storage mechanism." Journal of Glaciology 55, no. 193 (2009): 889–98. http://dx.doi.org/10.3189/002214309790152447.
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AbstractWe present results of an investigation of two jökulhlaups (glacial lake outburst floods) at Gornergletscher, Switzerland, using dye-tracer experiments and complementary hydrological measurements. Repeated dye injections into moulins showed that tracer transit speeds were larger after the lake had emptied, but when proglacial discharge was still high, than during the main phase of the jökulhlaup. This counter-intuitive finding was modelled by tracer retardation inside the injection moulin. This model, together with an estimate of the maximum time the tracer takes to transit the injection moulin, allows us to calculate bounds on the transit speed in the main drainage channel where the lake water flows. These results indicate that the main drainage channel transit speeds are indeed highest during the peak of the flood. Moreover, it is known from a previous study that water amounting to half of the lake volume is temporarily stored within the glacier during a Gornergletscher jökulhlaup. Our observations suggest that this process occurred via lateral spreading of water at the glacier bed.
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Huseby, Olaf K., Mona Andersen, Idar Svorstol, and Oyvind Dugstad. "Improved Understanding of Reservoir Fluid Dynamics in the North Sea Snorre Field by Combining Tracers, 4D Seismic, and Production Data." SPE Reservoir Evaluation & Engineering 11, no. 04 (August 1, 2008): 768–77. http://dx.doi.org/10.2118/105288-pa.
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Summary To obtain improved oil recovery (IOR), it is crucial to have a best-possible description of the reservoir and the reservoir dynamics. In addition to production data, information can be obtained from 4D seismic and from tracer monitoring. Interwell tracer testing (IWTT) has been established as a proven and efficient technology to obtain information on well-to-well communication, heterogeneities, and fluid dynamics. During such tests, chemical or radioactive tracers are used to label water or gas from specific wells. The tracers then are used to trace the fluids as they move through the reservoir together with the injection phase. At first tracer breakthrough, IWTT yields immediate and unambiguous information on injector/producer communication. Nevertheless, IWTT is still underused in the petroleum industry, and data may not be used to their full capacity--most tracer data are used in a qualitative manner (Du and Guan 2005). To improve this situation, we combine tracer-data evaluation, 4D seismic, and available production data in an integrated process. The integration is demonstrated using data from the Snorre field in the North Sea. In addition to production data, extensive tracer data (dating back to 1993) and results from three seismic surveys acquired in 1983, 1997, and 2001 were considered. Briefly this study shows thatSeismic and tracer data applied in combination can reduce the uncertainties in interpretations of the drainage patterns.Waterfronts interpreted independently by tracer response and seismic dimming compare well.Seismic brightening interpreted as gas accumulation is supported by the gas-tracer responses. Introduction The Snorre field is located in the Tampen Spur area on the Norwegian continental shelf and is a system of rotated fault blocks with beds dipping 4 to 10° toward the northwest. The reservoir sections are truncated by the Base Cretaceous unconformity. The reservoir sections consist of fluvial deposits of the Statfjord and Lunde formations. The reservoir units contain thin sand layers with alternating shale in a complex fault pattern. A challenge regarding optimization of the reservoir drainage, as well as oil production, is to understand how the different sand layers communicate and to what degree the faults act as barriers or not. The present work concentrates on the integration of 4D-seismic and tracer methods to obtain information on fluid flow in the Upper Statfjord (US) and Lower Statfjord (LS) formations in the Central Fault Block (CFB). The outline of this fault block is indicated in Fig. 1. The net/gross ratio is higher and the reservoir quality is generally better in the US than the LS formation. The CFB is produced by water-alternating-gas (WAG) injection as the drive mechanism, where the injectors are placed downdip and the producers updip. The average reservoir pressure in the CFB is 300 bar, and the reservoir temperature is 90°C. Tracer data are used to understand fluid flow in the reservoir. The data give valuable information about the dynamic behavior and well communication, but in some cases the interpretation may be complicated by reinjection of produced gas and water. Tracer studies in the Snorre field have been presented previously in several papers (Dugstad et al. 1999; Ali et al. 2000; Aurdal et al. 2001). To use the data fully, however, integration with other types of reservoir data is important. The main objectives of the seismic monitoring of Snorre are to contribute to increased oil recovery and to optimize placement of new wells. 4D analysis, together with tracers, should potentially increase the multidisciplinary understanding of the drainage pattern in the reservoirs. The results should, in addition to all the reservoir and production data, be used actively in target-remaining-oil processes and in well planning. In addition, the 4D data can give input to update the geological model and simulation model (history matching) and to identify possible well interventions. There is also a potential to include the data in workflows to identify lithology changes.
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Giertzuch, Peter-Lasse, Joseph Doetsch, Mohammadreza Jalali, Alexis Shakas, Cédric Schmelzbach, and Hansruedi Maurer. "Time-lapse ground penetrating radar difference reflection imaging of saline tracer flow in fractured rock." GEOPHYSICS 85, no. 3 (April 28, 2020): H25—H37. http://dx.doi.org/10.1190/geo2019-0481.1.
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The characterization of flow and transport processes in fractured rock is challenging because they cannot be observed directly and hydrologic tests can only provide sparse and local data. Time-lapse ground penetrating radar (GPR) can be a valuable tool to monitor such processes in the subsurface, but it requires highly reproducible data. As part of a tracer injection experiment at the Grimsel Test Site (GTS) in Switzerland, borehole reflection GPR data were acquired in a time-lapse survey to monitor saline tracer flow through a fracture network in crystalline rock. Because the reflections from the tracer in the sub-mm fractures appear extremely weak, a differencing approach has been necessary to identify the tracer signal. Furthermore, several processing steps and corrections had to be applied to meet the reproducibility requirements. These steps include (1) single-trace preprocessing, (2) temporal trace alignment, (3) correction of sampling rate fluctuations, (4) spatial trace alignment, (5) spike removal, and (6) postprocessing procedures applied to the difference images. This allowed successful tracer propagation monitoring with a clear signal that revealed two separate tracer flow paths. The GPR results are confirmed by conductivity meters that were placed in boreholes in the GTS. If sufficient data processing is applied, GPR is shown to be capable of resolving tracer flow through sub-mm aperture fractures by difference reflection imaging even in challenging surroundings where many reflectors are present.
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Zeng, Xian Yang, Zuo He Chi, Ming Guang Zheng, Gong Gang Sun, Guang Xue Zhang, and Jin Qing Wang. "Experiment Research on Air Flow Rate Measurement Using Tracer Gas Method." Advanced Materials Research 374-377 (October 2011): 520–23. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.520.
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Experiment research on the air flow rate measurement using tracer gas method in a 300mm internal diameter and 90° elbow duct are presented, which CO and air are selected as tracer gas and gas stream. Results show that the relative errors between the flow rate measured by tracer gas method and turbine flowmeter are varied in the range of -2.15%~1.69% when the injection point is upstream of the elbow on 7D~13D (D is the internal diameter of the duct), and the sampling point is downstream of the elbow on 10D~14D. The further distances of the injection point and sampling point are apart, the less relative errors of the gas flow rate measured by tracer gas method and turbine flowmeter are made. The injection flow rate of tracer gas should be matched with the gas flow rate in the duct. It is a simple and effective method that gas flowmeter online calibration with tracer gas method on the large diameter industrial gas pipeline transportation.
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Siberlin, C., and C. Wunsch. "Oceanic tracer and proxy time scales revisited." Climate of the Past Discussions 6, no. 5 (September 1, 2010): 1589–628. http://dx.doi.org/10.5194/cpd-6-1589-2010.
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Abstract. Quantifying time-responses of the ocean to passive and active tracers is critical for the interpretation of paleodata from sediment cores because surface-injected tracers do not instantaneously spread throughout the ocean. To obtain insights into the time response, a computationally efficient state transition matrix method is demonstrated and used to compute successive states of passive tracer concentrations in the global ocean. Times to equilibrium exceed a thousand years for any one region of the global ocean outside of the injection and convective regions and concentration gradients give time-lags from hundreds to thousands of years between the Atlantic and Pacific abyss, depending on the injection region and the nature of the boundary conditions employed. Equilibrium times can be much longer than radiocarbon ages as the latter are strongly biased towards the youngest fraction of fluid captured in a sample. Pulse-like inputs can produce very different transient approaches to equilibrium in different parts of the ocean generating event identification problems.
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Somogyvári, Márk, Peter Bayer, and Ralf Brauchler. "Travel-time-based thermal tracer tomography." Hydrology and Earth System Sciences 20, no. 5 (May 12, 2016): 1885–901. http://dx.doi.org/10.5194/hess-20-1885-2016.
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Abstract. Active thermal tracer testing is a technique to get information about the flow and transport properties of an aquifer. In this paper we propose an innovative methodology using active thermal tracers in a tomographic setup to reconstruct cross-well hydraulic conductivity profiles. This is facilitated by assuming that the propagation of the injected thermal tracer is mainly controlled by advection. To reduce the effects of density and viscosity changes and thermal diffusion, early-time diagnostics are used and specific travel times of the tracer breakthrough curves are extracted. These travel times are inverted with an eikonal solver using the staggered grid method to reduce constraints from the pre-defined grid geometry and to improve the resolution. Finally, non-reliable pixels are removed from the derived hydraulic conductivity tomograms. The method is applied to successfully reconstruct cross-well profiles as well as a 3-D block of a high-resolution fluvio-aeolian aquifer analog data set. Sensitivity analysis reveals a negligible role of the injection temperature, but more attention has to be drawn to other technical parameters such as the injection rate. This is investigated in more detail through model-based testing using diverse hydraulic and thermal conditions in order to delineate the feasible range of applications for the new tomographic approach.
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Matsumoto, Takeshi, Hiroyuki Tachibana, Yasuo Ogasawara, and Fumihiko Kajiya. "New double-tracer digital radiography for analysis of spatial and temporal myocardial flow heterogeneity." American Journal of Physiology-Heart and Circulatory Physiology 280, no. 1 (January 1, 2001): H465—H474. http://dx.doi.org/10.1152/ajpheart.2001.280.1.h465.
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A new high-resolution digital radiographic technique based on the deposition of125I- and 3H-labeled desmethylimipramine (IDMI and HDMI, respectively) was developed for the assessment of spatial and temporal myocardial flow heterogeneity at a microvascular level. The density distributions of two tracers, or relative flow distributions, were determined by subtraction digital radiography using two imaging plates of different sensitivity. The regions resolved are comparable in size to vascular regulatory units (400 × 400 μm2). This method was applied to the measurement of within-layer myocardial flow distributions in Langendorff-perfused rabbit hearts. The validity of this method was confirmed by the strong correlation between regional densities of two tracers injected simultaneously ( r = 0.89 ± 0.03, n = 8). The temporal flow stability was evaluated by a 90-s continuous IDMI injection and subsequent bolus HDMI injection ( n = 8). Regional densities of the two tracers were fairly correlated ( r = 0.86 ± 0.03), indicating that the spatial pattern of flow distribution was stable even at a microvascular level over a 90-s period. The effect of microsphere embolization on the flow distribution was also investigated by the sequential injections of IDMI, 15-μm microspheres, and HDMI at 20-s intervals ( n = 8). Microembolization increased the coefficient of variation of tracer density from 19 to 25% ( P < 0.05), whereas the regional densities of two tracers were still correlated substantially, as in the case of no embolization ( r = 0.84 ± 0.06). Thus the microsphere embolization enhanced flow heterogeneity with increasing flow differences between control high-flow and control low-flow regions but rather maintained the pattern of flow distribution. In conclusion, double-tracer digital radiography will be a promising method for the spatial and temporal myocardial flow analysis at microvascular levels.
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Chapman, Molly C., Amie Y. Lee, Jessica H. Hayward, Bonnie N. Joe, and Elissa R. Price. "Superparamagnetic Iron Oxide Sentinel Node Tracer Injection: Effects on Breast MRI Quality." Journal of Breast Imaging 2, no. 6 (October 27, 2020): 577–82. http://dx.doi.org/10.1093/jbi/wbaa083.
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Abstract Objective To evaluate the MRI artifact rendered by the typical injection of a ferromagnetic tracer now being intermittently used for intraoperative sentinel node (SN) identification at our institution, and to explore its impact on postoperative imaging and management. Methods This study was Institutional Review Board-approved and granted a waiver of consent. A database search tool was used to identify MRI exams performed on patients who had previously undergone breast-conserving surgery with use of a superparamagnetic iron oxide (SPIO) SN tracer between January 1, 2015, and May 1, 2020. MRI reports, images, and relevant demographic, oncologic, and surgical history were collected. The presence or absence of SPIO residue on breast MRI, as well as its impact on image quality, were extracted from the prospective reports. Results A total of 21 MRI exams were identified in 16 patients who had undergone breast-conservation therapy for cancer with use of SPIO SN tracer. Mean time from particle injection to baseline postoperative MRI exam was 10.8 months. All reports (21/21) noted evidence of SPIO residue. Of these, 5/21 were assessed as non-diagnostic; the remainder were assessed as limited. Conclusion Radiologists should be aware of the use of superparamagnetic tracers for SN identification and the impact on the quality of future MRI examinations. Alternative injection approaches are being developed and sequence parameters adjusted to minimize artifact.
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Watson, Philip D. "Analysis of the paired-tracer method of determining cell uptake." American Journal of Physiology-Endocrinology and Metabolism 275, no. 2 (August 1, 1998): E366—E371. http://dx.doi.org/10.1152/ajpendo.1998.275.2.e366.
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The paired-tracer method has been used extensively for determining cell uptake of numerous substances, although the method of calculating uptake has no published theoretical support. We have investigated the effect of capillary permeability of the tracers on v, the uptake rate calculated directly from the ratio of tracer venous concentrations. For a simple mathematical model of plasma-tissue movement of lactate and an analytic expression for v, it has been shown that values of v calculated in the first moments after tracer injection depend almost entirely on the differences in tracer permeability-surface area product (PS). The model indicates v would never give the correct value of cell uptake. It is also shown that PS differences alone can explain the published values for lactate uptake obtained from v in skeletal muscle of the rat and dog.
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Hill, A. D., and J. Ricardo Solares. "Improved Analysis Methods for Radioactive Tracer Injection Logging." Journal of Petroleum Technology 37, no. 03 (March 1, 1985): 511–20. http://dx.doi.org/10.2118/12140-pa.
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Young, Dirk F., and William P. Ball. "Injection Mode Effects on Tracer Experiments in Columns." Journal of Hydrologic Engineering 2, no. 3 (July 1997): 113–19. http://dx.doi.org/10.1061/(asce)1084-0699(1997)2:3(113).
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Brouyere, Serge, Guy Carabin, and Alain Dassargues. "Influence of injection conditions on field tracer experiments." Ground Water 43, no. 3 (May 2005): 389–400. http://dx.doi.org/10.1111/j.1745-6584.2005.0041.x.
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Lassen, Niels A. "Neuroreceptor Quantitation in vivo by the Steady-State Principle Using Constant Infusion or Bolus Injection of Radioactive Tracers." Journal of Cerebral Blood Flow & Metabolism 12, no. 5 (September 1992): 709–16. http://dx.doi.org/10.1038/jcbfm.1992.101.
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The approaches hitherto used for measuring the kinetic constants Kd and Bmax of neuroreceptors in vivo all violate the steady state of the system. This complicates the kinetic analysis as approximations must be made, introducing errors of unknown magnitude. The present study presents the theory for designing experiments in which the steady state is preserved. It is based on maintaining a constant degree of receptor binding (occupancy) throughout the experiment. This is achieved by administering by prolonged intravenous infusion the non-radioactive ligand one wishes to study. The fraction of receptor sites not occupied by the “cold” ligand is measured by using trace amounts of a radioactive ligand binding to the same receptor. A minimum of two studies at different occupancies must be performed. In this presentation it is proposed to make the second study at essentially zero receptor occupancy by administering the tracer alone. The pair of tracer studies, the one without and the other with infusion of cold ligand, allows calculation of the cold ligand's equilibrium dissociation constant Kd. In the special case when tracer and cold ligands are chemically identical, then Bmax can also be calculated. Two different modes of tracer administration can be used. If the tracer is also infused at a constant rate for a long time, then the occupancy of receptor sites by the cold ligand can be calculated by measuring the equilibrium tracer concentrations in brain and plasma. If the tracer is administered as an intravenous bolus injection, then the area under the brain and plasma radioactivity curves or compartmental analysis must be used. The bolus injection approach, described in this paper for the first time, has the highest overall counting efficiency and should therefore be particularly suited for studies in man using positron emission tomography (PET) or single photon emission tomography (SPECT). Tracer infusion is the method of choice for animal experiments, as only one set of values are needed, those at long time, as can be obtained post vivo by counting samples of brain or by using autoradiographic techniques. The steady-state principle shows that ligands with very low Kd values, i.e., with very high affinity, are not suited for receptor quantitation.
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Siberlin, C., and C. Wunsch. "Oceanic tracer and proxy time scales revisited." Climate of the Past 7, no. 1 (January 11, 2011): 27–39. http://dx.doi.org/10.5194/cp-7-27-2011.
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Abstract. Quantifying time-responses of the ocean to tracer input is important to the interpretation of paleodata from sediment cores – because surface-injected tracers do not instantaneously spread throughout the ocean. To obtain insights into the time response, a computationally efficient state-transition matrix method is demonstrated and used to compute successive states of passive tracer concentrations in the global ocean. Times to equilibrium exceed a thousand years for regions of the global ocean outside of the injection and convective areas and concentration gradients give time-lags from hundreds to thousands of years between the Atlantic and Pacific abyss, depending on the injection region and the nature of the boundary conditions employed. Equilibrium times can be much longer than radiocarbon ages – both because the latter are strongly biased towards the youngest fraction of fluid captured in a sample, and because they represent distinct physical properties. Use of different boundary conditions – concentration, or flux – produces varying response times, with the latter depending directly upon pulse duration. With pulses, the sometimes very different transient approach to equilibrium in various parts of the ocean generates event identification problems.
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Wirestam, R., V. Andrée Larsen, M. Stubgaard, C. Thomsen, B. Vikhoff, H. B. W. Larsson, F. Ståhlberg, and O. Henriksen. "Deuterium MR Spectroscopy at 4.7 T." Acta Radiologica 36, no. 1 (January 1995): 85–91. http://dx.doi.org/10.1177/028418519503600116.
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Deuterium MR spectroscopy was used for the determination of tissue blood flow (TBF). The tracer D2O was injected into the tissue of interest, and tracer washout was followed using a 4.7 T spectroscopy/imaging unit. Normal subcutaneous tissue in rats was studied, as well as tissue influenced by vasoactive agents (papaverine and adrenaline). The vasoactive agents introduced changes of 40% in TBF, compared with normal tissue. Normal tissue measurements were repeated using various D2O injection volumes (5–400 μl). The injection volume 5 μl gave TBF 11.7 ± 2.0 ml/100 g·min (mean ± 1 SD). This value was 40% higher than corresponding values observed at larger injection volumes (200–400 μl). This injection volume effect is probably partly due to a capillary dilution caused by tracer administration, and partly related to the non-physiological deuterium signal decrease observed in dead rats. Blood flow measurements in human colon tumours implanted in nude mice showed a rather poor reproducibility, not improved by the use of a multiple site injection technique.
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Michelet, Å. Aulie. "Effects of Intravascular Contrast Media on Blood-Brain Barrier." Acta Radiologica 28, no. 3 (May 1987): 329–33. http://dx.doi.org/10.1177/028418518702800320.
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The effects upon the rabbit blood-brain barrier after intracarotid injection of two non-ionic contrast media, iopentol (a monomer) and iodixanol (a dimer) were compared. Iothalamate and iohexol were used as reference substances. 99Tcm-DTPA, 125I-HSA and Trypsin blue were used as tracers in order to demonstrate various degrees of damage to the barrier. Injection of iothalamate led to large extravasation of 99Tcm-DTPA, 125I-HSA and Trypan blue which means severe damage of the blood-brain barrier. Injection of iopentol and iohexol resulted in some extravasation of all three tracers used, whereas injection of iodixanol only led to extravasation of the small molecule tracer 99Tcm-DTPA demonstrating minor changes of the barrier. At computed tomography of the brain with intravascular contrast medium enhancement it is safer to use iodixanol than iothalamate. Iodixanol is expected to cause even less adverse effects to the brain after intraarterial injection than iopentol and iohexol.
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Cobelli, C., M. P. Saccomani, E. Ferrannini, R. A. Defronzo, R. Gelfand, and R. Bonadonna. "A compartmental model to quantitate in vivo glucose transport in the human forearm." American Journal of Physiology-Endocrinology and Metabolism 257, no. 6 (December 1, 1989): E943—E958. http://dx.doi.org/10.1152/ajpendo.1989.257.6.e943.
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Glucose transport is a critical step in the control of glucose disposal that, until presently, has not been quantitated in vivo in humans. We have employed the perfused forearm and euglycemic insulin-clamp techniques in combination with a dual-tracer injection to measure basal and insulin-mediated glucose transport in six normal subjects. L-[3H]glucose, which is not transported, was used to trace extracellular glucose kinetics; 3-O-[14C]-methyl-D-glucose, transportable but not metabolizable, was used to monitor glucose movement across the cell membrane. After bolus intra-arterial injection of the two tracers, plasma samples were obtained every 15-30 s for 10 min from a deep forearm vein to determine the washout curves. A linear compartmental model was developed that accounts for blood flow heterogeneity. It consists of three parallel, two-compartment chains merging into the sampling compartment to which cellular compartments are appended. A priori identifiability analysis was performed. The uniquely identifiable parameterization includes the transport rate constants of glucose into and out of the cell. The model was identified using nonlinear least-squares parameter estimation. Transport parameters are estimated with very good precision, and their reproducibility is satisfactory. The model also allows the estimation of the mean arteriovenous transit times of both the extracellular and the transported tracer. The compartmental model provides a novel approach to investigate glucose transport in vivo in humans.
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Pecly, J. O. G., and J. S. F. Roldão. "Dye tracers as a tool for outfall studies: dilution measurement approach." Water Science and Technology 67, no. 7 (April 1, 2013): 1564–73. http://dx.doi.org/10.2166/wst.2013.027.
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Dye tracer technique is well established and of wide application for assessment of outfalls and for delineation of near field and far field extensions. Common goals of a tracer study include the measurement of the dilution factor, estimation of the dispersion coefficients, measurement of the effluent discharge and calibration of a contaminant transport model. This paper presents a brief review of the methods involving the use of dye tracer for outfall assessment and illustrates the methods of slug release and continuous injection based on two real cases of campaigns carried out on Brazilian coastal waters. Slug injection on the surface of the water body was used for preliminary dispersion studies aiming at outfall positioning. During the operational phase of an outfall, the continuous injection of dye tracer was used to determine effluent dilution in different seasons. In coastal waters of Rio de Janeiro city, sea current pattern, tidal modulation and thermal stratification explained the main features of the dilution field.
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Liu, H., I. J. Llewellyn-Smith, and A. I. Basbaum. "Co-injection of wheat germ agglutinin-HRP and choleragenoid-HRP into the sciatic nerve of the rat blocks transganglionic transport." Journal of Histochemistry & Cytochemistry 43, no. 5 (May 1995): 489–95. http://dx.doi.org/10.1177/43.5.7730587.
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We report on the surprising loss of transganglionic and retrograde labeling in the spinal cord of the rat after co-injection of the tracers wheat germ agglutinin-HRP (WGA-HRP) and choleragenoid toxin-HRP (CTB-HRP) into the sciatic nerve. Injection of WGA-HRP alone produced a pattern of transganglionic label consistent with transport by small-diameter primary afferent fibers. Small cell bodies were labeled in the ipsilateral dorsal root ganglion (DRG) and there was dense terminal labeling in the superficial dorsal horn of the lumbar spinal cord. Injection of CTB-HRP alone produced a pattern of transganglionic labeling consistent with transport by large-diameter primary afferent fibers. Large cell bodies were labeled in the DRG and there was dense terminal labeling in the nucleus proprius (Laminae III-V) in the spinal cord. CTB-HRP also produced extensive retrograde labeling of ventral horn motor neurons. When the two tracers were co-injected, we found few labeled cells in the ipsilateral DRG and there was almost complete loss of transganglionic terminal labeling in the lumbar spinal cord. Retrograde labeling of motor neurons was also significantly reduced. Even when one of the tracers (e.g., WGA-HRP) was injected 24 hr after and up to 10 mm proximal to the site of the first tracer (e.g., CTB-HRP), an inhibitory interaction was detected. The labeling pattern was always characteristic of the first tracer injected.(ABSTRACT TRUNCATED AT 250 WORDS)
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Nguyen, Quoc P., William R. Rossen, Pacelli L. J. Zitha, and Peter K. Currie. "Determination of Gas Trapping With Foam Using X-Ray Computed Tomography and Effluent Analysis." SPE Journal 14, no. 02 (May 31, 2009): 222–36. http://dx.doi.org/10.2118/94764-pa.
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Summary Foam is used worldwide to improve acid placement in matrix acid treatments and to redirect gas flow in improved oil recovery. Gas trapping is a major factor in foam processes; it affects foam mobility and controls diversion of liquids such as acid injected after foam. Most previous studies of gas trapping have relied on fitting effluent-gas tracer profiles to a 1D model for transport of tracer in the presence of trapped gas, including mass transfer between flowing and trapped gas. We present new experiments where X-ray computed tomography (CT) directly determines the gas-tracer distribution in situ. The key is using a gas-phase tracer [xenon (Xe)] visible in CT. The CT images show clearly that the standard 1D model used to interpret tracer effluent profiles is incorrect in its assumptions. For the first time, here we compare the in-situ tracer distribution from CT images to the trapped-gas saturation estimated from fitting the effluent tracer profile to the 1D model, augmented here for the effect of pressure variation along the core. The effluent profile is determined indirectly from the CT images in two ways:by imaging the tracer concentration in the flowline downstream of the core andby using a mass balance on the tracer in the core. Estimates of trapped-gas fraction using the 1D model vary by as much as a factor of 0.2 among reasonable fits to the effluent data, and flowing-gas fraction varies by as much as a factor of 1.5 or 2. The experiments span a range of foam qualities and injection rates in Bentheim sandstone. Estimates of trapped-gas fraction derived from the 1D model decrease with increasing gas-injection rate and increase weakly with increasing liquid-injection rate in our experiments. The CT images show a shift to a wider variety of fluctuating flow paths as liquid- or gas-injection rate increases.
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Hock, Regine, lmut Iken, and Alexander Wangler. "Tracer experiments and borehole observations in the over-deepening of Aletschgletscher, Switzerland." Annals of Glaciology 28 (1999): 253–60. http://dx.doi.org/10.3189/172756499781821742.
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AbstractThe subglacial drainage in a pronounced overdeepening of Grosser Aletschgletscher, Switzerland was investigated by borehole water-level observations and dye-tracer injections. In August 1990 and 1991, tracer was injected at the bottom of a borehole (depth 904 m and 710 m, respectively), and simultaneously in a nearby moulin. The moulin and borehole injections identified two different flow systems coexisting within the overdeepening. The moulin injection yielded short-lived, highly peaked break-through curves with high velocities, indicating a hydraulically efficient channelized system. The borehole-tracer return occurred in broad multiple peaks characterized by a striking diurnal periodicity and, in general, correlated inversely with discharge. Water level in the borehole experienced high diurnal variations in phase with discharge at the snout indicating “closed channel flow” over large parts of the glacier. We infer that the boreholes drained subglacially and were connected to a drainage system with significant long-term storage capacity. Release of labelled water was triggered by daily water-pressure cycles.
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Rossi, P., N. Dörfliger, K. Kennedy, I. Müller, and M. Aragno. "Bacteriophages as surface and ground water tracers." Hydrology and Earth System Sciences 2, no. 1 (March 31, 1998): 101–10. http://dx.doi.org/10.5194/hess-2-101-1998.
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Abstract. Bacteriophages are increasingly used as tracers for quantitative analysis in both hydrology and hydrogeology. The biological particles are neither toxic nor pathogenic for other living organisms as they penetrate only a specific bacterial host. They have many advantages over classical fluorescent tracers and offer the additional possibility of multi-point injection for tracer tests. Several years of research make them suitable for quantitative transport analysis and flow boundary delineation in both surface and ground waters, including karst, fractured and porous media aquifers. This article presents the effective application of bacteriophages based on their use in differing Swiss hydrological environments and compares their behaviour to conventional coloured dye or salt-type tracers. In surface water and karst aquifers, bacteriophages travel at about the same speed as the typically referenced fluorescent tracers (uranine, sulphurhodamine G extra). In aquifers of interstitial porosity, however, they appear to migrate more rapidly than fluorescent tracers, albeit with a significant reduction in their numbers within the porous media. This faster travel time implies that a modified rationale is needed for defining some ground water protection area boundaries. Further developments of other bacteriophages and their documentation as tracer methods should result in an accurate and efficient tracer tool that will be a proven alternative to conventional fluorescent dyes.
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Yang, Qing Chun. "A Comparative Study on Scoping Numerical Calculations of Anisotropic Diffusion Experiment in Clay." Applied Mechanics and Materials 148-149 (December 2011): 1434–37. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.1434.
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Safety assessment of nuclear waste disposal in a deep geological repository requires understanding and quantifying radionuclide transport through the hosting geological formation. Radionuclide diffusion is the main transport mechanism in clay formations since they usually have small hydraulic conductivities. Thus, understanding diffusion and determining diffusion parameters under real conditions is crucial for the performance assessment of a deep geological repository. In this paper, a comparative analysis is performed which focus on the dimensions of the packed-off section where tracers are injected and the packer between the intervals, diffusion of neutral (HTO), anionic (I) and sorbing cationic tracers with different distribution coefficients (22Na and 85Sr) has been simulated considering the anisotropy effect. The results indicate that The expected anisotropy has been clearly measurable for the sake of a short injection interval, in the final geometric configuration, the length of injection interval is larger than the transport distance, so the anisotropy effect is not as clearly measurable as in the preliminary because practically no tracer breakthrough from one interval to the other is expected if diffusion anisotropy is confirmed. The tracer depletion in the final design is larger than in the preliminary design.
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SUDO, Shigeru, Naoki TAMURA, Diana KALININA, Igor VINYAR, Kuninori SATO, Evgeny VESHCHEV, Pavel GONCHAROV, et al. "Multi-Functional Diagnostic Method with Tracer-Encapsulated Pellet Injection." Plasma and Fusion Research 2 (2007): S1013. http://dx.doi.org/10.1585/pfr.2.s1013.
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Kobayashi, D., T. Asai, S. Yamada, Y. Ishikawa, N. Tamura, and Y. Narushima. "Development of a tracer-containing compact-toroid injection system." Review of Scientific Instruments 89, no. 10 (October 2018): 10I111. http://dx.doi.org/10.1063/1.5039310.
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Cheong, K. W. "HVAC ductwork: Constant-injection tracer-gas assessment of airtightness." Building Services Engineering Research and Technology 19, no. 3 (August 1998): 171–74. http://dx.doi.org/10.1177/014362449801900310.
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Fortenberry, Robert, Pearson Suniga, Mojdeh Delshad, Bharat Singh, Hassan A. AlKaaoud, Charlie T. Carlisle, and Gary A. Pope. "Design and Demonstration of New Single-Well Tracer Test for Viscous Chemical Enhanced-Oil-Recovery Fluids." SPE Journal 21, no. 04 (August 15, 2016): 1075–85. http://dx.doi.org/10.2118/178914-pa.
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Summary Single-well-partitioning-tracer tests (SWTTs) are used to measure the saturation of oil or water near a wellbore. If used before and after injection of enhanced-oil-recovery (EOR) fluids, they can evaluate EOR flood performance in a so-called one-spot pilot. Four alkaline/surfactant/polymer (ASP) one-spot pilots were recently completed in Kuwait's Sabriyah-Mauddud (SAMA) reservoir, a thick, heterogeneous carbonate operated by Kuwait Oil Company (KOC). UTCHEM (Delshad et al. 2013), the University of Texas chemical-flooding reservoir simulator, was used to interpret results of two of these one-spot pilots performed in an unconfined zone within the thick SAMA formation. These simulations were used to design a new method for injecting partitioning tracers for one-spot pilots. The recommended practice is to inject the tracers into a relatively uniform confined zone, but, as seen in this work, that is not always possible, so an alternative design was needed to improve the accuracy of the test. The simulations showed that there was a flow-conformance problem when the partitioning tracers were injected into a perforated zone without confinement after the viscous ASP and polymer-drive solutions. The water-conveyed-tracer solutions were being partially diverted outside of the ASP-swept zone where they contacted unswept oil. Because of this problem, the initial interpretation of the performance of the chemicals was pessimistic, overestimating the chemical residual oil saturation (ROS) by up to 12 saturation units. Additional simulations indicated that the oil saturation in the ASP-swept zone could be properly estimated by avoiding the post-ASP waterflood and injecting the post-ASP tracers in a viscous polymer solution rather than in water. An ASP one-spot pilot using the new SWTT design resulted in an estimated ROS of only 0.06 after injection of chemicals (Carlisle et al. 2014). These saturation values were obtained by history matching tracer-production data by use of both traditional continuously-stirred-tank (CSTR) models and compositional, reactive-transport reservoir models. The ability of the simulator to model every phase of the one-spot pilot operation was crucial to the insight of modified SWTT design. The waterflood, first SWTT, ASP flood, and the final SWTT were simulated using a heterogeneous permeability field representative of the Mauddud formation. Laboratory data, field-ASP quality-control information, and injection strategy were all accounted for in these simulations. We describe the models, how they were used, and how the results were used to modify the SWTT design. We further discuss the implications for other SWTTs. The advantage of mechanistic simulation of multiple aspects of a one-spot pilot is an important theme of this study. Because the pore space investigated by the SWTTs can be affected by the previously injected EOR fluids (and vice versa), these interactions should be accounted for. This simulation approach can be used to identify and mitigate design problems during each phase of a challenging one-spot pilot.
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Hoffer, L. John, Mazen J. Hamadeh, Line Robitaille, and Kenneth H. Norwich. "Human sulfate kinetics." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 289, no. 5 (November 2005): R1372—R1380. http://dx.doi.org/10.1152/ajpregu.00325.2005.
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Electrospray tandem mass spectrometry was used to determine steady-state serum and urinary inorganic sulfate and sulfate ester kinetic profiles of nine normal men after intravenous injection of the stable isotope sodium [34S]sulfate. Sulfate ester appearance was traced by eliminating inorganic sulfate from samples, followed by hydrolysis of sulfate esters to inorganic sulfate for analysis. Whole body inorganic sulfate turnover in steady state was calculated using standard tracer techniques. Rate of appearance and disappearance of inorganic sulfate was 841 ± 49 μmol/h. Average urinary inorganic sulfate excretion was 609 ± 41 μmol/h, and the whole body sulfation rate (total rate of disappearance minus rate of urinary excretion) was 232 ± 36 μmol/h. Tracer-labeled sulfate esters appeared in serum and urine within 1 h of tracer injection. The kinetics of inorganic sulfate and sulfate esters were linked by means of a compartmental model. The appearance and excretion of sulfate esters accounted for ∼ 50% of the total sulfation rate. These results indicate that human whole body sulfation accounts for ∼ 27% of inorganic sulfate turnover and that extracellular inorganic sulfate is an important pool for intracellular sulfation. A substantial fraction of newly synthesized sulfate esters promptly enters the extracellular space for excretion in the urine.
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Wolkersdorfer, Christian, and Jenna LeBlanc. "Regulations, legislation, and guidelines for artificial surface water and groundwater tracer tests in Canada." Water Quality Research Journal 47, no. 1 (February 1, 2012): 42–55. http://dx.doi.org/10.2166/wqrjc.2012.042.
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This paper describes Canadian federal and provincial regulations, legislation, and guidelines for artificial tracer tests, where substances are released into water, and provides a world-wide comparison. Alberta is currently the only Canadian province with guidelines and regulations relating to those tests. None of the other provinces have specific tracer test regulations in place, though the injection of artificial substances into waters is covered by Section 36(3) of the federal Fisheries Act. Newfoundland and Labrador, the Northwest Territories, and Nunavut sometimes require a permit to conduct a tracer test, and Quebec is planning to implement guidelines and regulations based on Michigan/USA Environmental Quality guidelines. In each case Fisheries and Oceans Canada (DFO), Environment Canada, and the Provincial environment departments should be contacted and the proposed test described as detailed as necessary. We present potential tracers, such as uranine (sodium fluorescein), or Rhodamine WT, that can be used in artificial tracer tests. This study is the result of contacting personnel from organizations such as Environment Canada, Fisheries and Oceans Canada, provincial departments of environment, researchers, and consultants.
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Laing, Robyn J., Jurate Lasiene, and Jaime F. Olavarria. "Topography of Striate-Extrastriate Connections in Neonatally Enucleated Rats." BioMed Research International 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/592426.
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It is known that retinal input is necessary for the normal development of striate cortex and its corticocortical connections, but there is little information on the role that retinal input plays in the development of retinotopically organized connections between V1 and surrounding visual areas. In nearly all lateral extrastriate areas, the anatomical and physiological representation of the nasotemporal axis of the visual field mirrors the representation of this axis in V1. To determine whether the mediolateral topography of striate-extrastriate projections is preserved in neonatally enucleated rats, we analyzed the patterns of projections resulting from tracer injections placed at different sites along the mediolateral axis of V1. We found that the correlation between the distance from injection sites to the lateral border of V1 and the distance of the labeling patterns in area 18a was strong in controls and much weaker in enucleates. Data from pairs of injections in the same animal revealed that the separation of area 18a projection fields for a given separation of injection sites was more variable in enucleated than in control rats. Our analysis of single and double tracer injections suggests that neonatal bilateral enucleation weakens, but not completely abolishes, the mediolateral topography in area 18a.
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Radtke, Christine, Jeffery D. Kocsis, Wolfgang Baumgärtner, and Peter M. Vogt. "Fluoro-Ruby as a reliable marker for regenerating fiber tracts." Innovative Surgical Sciences 2, no. 1 (March 1, 2017): 9–13. http://dx.doi.org/10.1515/iss-2016-0019.
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AbstractAxon visualization techniques are important in assessing the efficacy of interventional approaches to stimulate neural regeneration. Whereas the labeling of descending tracts in the spinal cord has been well established using the intracortical injection of biotin dextran amine (BDA), the labeling of ascending sensory fibers of the dorsal funiculus is more problematic. Fluoro-Ruby (FR; dextran tetramethylrhodamine; MW 10,000) is a bidirectional permanent tracer, but the retrograde tracing of fibers is particularly prominent, and FR is a highly sensitive tracer that can be applied in discrete injection sites. In the present report, we used FR to efficiently label ascending fibers in the dorsal columns of the rat spinal cord. After transplantation of olfactory ensheathing cells into the transected dorsal funiculus, the application of FR was able to detect regenerating ascending fibers in the spinal cord. Regenerated fibers crossing the injury site were labeled and easily identified. It is likely that the tracer was taken up by damaged fibers. As additional advantages, the labeling is resistant to photobleaching and no additional tissue processing is necessary for visualization. It can be used for in vivo as well as in vitro injections. The findings indicate that FR can be used as a reliable fluorescent marker to study ascending regenerated fibers in the spinal cord axonal regeneration.
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Saccomani, M. P., R. C. Bonadonna, D. M. Bier, R. A. DeFronzo, and C. Cobelli. "A model to measure insulin effects on glucose transport and phosphorylation in muscle: a three-tracer study." American Journal of Physiology-Endocrinology and Metabolism 270, no. 1 (January 1, 1996): E170—E185. http://dx.doi.org/10.1152/ajpendo.1996.270.1.e170.
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We studied five healthy subjects with perfused forearm and euglycemic clamp techniques in combination with a three-tracer (D-[12C]mannitol, not transportable; 3-O-[14C]methyl-D-glucose, transportable but not metabolizable; D-[3-3H]glucose, transportable and metabolizable) intra-arterial pulse injection to assess transmembrane transport and intracellular phosphorylation of glucose in vivo in human muscle. The washout curves of the three tracers were analyzed with a multicompartmental model. A priori identifiability analysis of the tracer model shows that the rate constants of glucose transport into and out of the cells and of glucose phosphorylation are uniquely identifiable. Tracer model parameters were estimated by a nonlinear least-squares parameter estimation technique. We then solved for the tracee model and estimated bidirectional transmembrane transport glucose fluxes, glucose intracellular phosphorylation, extracellular and intracellular volumes of glucose distribution, and extracellular and intracellular glucose concentrations. Physiological hyperinsulinemia (473 +/- 22 pM) caused 2.7-fold (63.1 +/- 7.2 vs. 23.4 +/- 6.1 mumol.min-1.kg-1, P < 0.01) and 5.1-fold (42.5 +/- 5.8 vs. 8.4 +/- 2.2 mumol.min-1.kg-1, P < 0.01) increases in transmembrane influx and intracellular phosphorylation of glucose, respectively. Extracellular distribution volume and concentration of glucose were unchanged, whereas intracellular distribution volume of glucose was increased (approximately 2-fold) and intracellular glucose concentration was almost halved by hyperinsulinemia. In summary, 1) a multicompartment model of three-tracer kinetic data can quantify transmembrane glucose fluxes and intracellular glucose phosphorylation in human muscle; and 2) physiological hyperinsulinemia stimulates both transport and phosphorylation of glucose and, in doing so, amplifies the role of glucose transport as a rate-determining step of muscle glucose uptake.
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Mihara, Kisyo, Sachiko Matsuda, Yuki Nakamura, Koichi Aiura, Akihiro Kuwahata, Shinichi Chikaki, Masaki Sekino, et al. "Intraoperative laparoscopic detection of sentinel lymph nodes with indocyanine green and superparamagnetic iron oxide in a swine gallbladder cancer model." PLOS ONE 16, no. 3 (March 11, 2021): e0248531. http://dx.doi.org/10.1371/journal.pone.0248531.
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Mapping of sentinel lymph nodes (SLNs) can enable less invasive surgery. However, mapping is challenging for cancers of difficult-to-access visceral organs, such as the gallbladder, because the standard method using radioisotopes (RIs) requires preoperative tracer injection. Indocyanine green (ICG) and superparamagnetic iron oxide (SPIO) have also been used as alternative tracers. In this study, we modified a previously reported magnetic probe for laparoscopic use and evaluated the feasibility of detecting SLNs of the gallbladder using a laparoscopic dual tracer method by injecting ICG and SPIO into five swine and one cancer-bearing swine. The laparoscopic probe identified SPIO nanoparticles in the nodes of 4/5 swine in situ, the magnetic field counts were 2.5–15.9 μT, and fluorescence was detected in SLNs in all five swine. ICG showed a visual lymph flow map, and SPIO more accurately identified each SLN with a measurable magnetic field quite similar to the RI. We then developed an advanced gallbladder cancer model with lymph node metastasis using recombination activating gene 2-knockout swine. We identified an SLN in the laparoscopic investigation, and the magnetic field count was 3.5 μT. The SLN was histologically determined to be one of the two metastatic lymph nodes. In conclusion, detecting the SLNs of gallbladder cancer in situ using a dual tracer laparoscopic technique with ICG and SPIO was feasible in a swine model.
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Drescher, Robert, Falk Gühne, and Martin Freesmeyer. "Early-Dynamic Positron Emission Tomography (PET)/Computed Tomography and PET Angiography for Endoleak Detection After Endovascular Aneurysm Repair." Journal of Endovascular Therapy 24, no. 3 (March 22, 2017): 421–24. http://dx.doi.org/10.1177/1526602817699397.
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Purpose: To propose a positron emission tomography (PET)/computed tomography (CT) protocol including early-dynamic and late-phase acquisitions to evaluate graft patency and aneurysm diameter, detect endoleaks, and rule out graft or vessel wall inflammation after endovascular aneurysm repair (EVAR) in one examination without intravenous contrast medium. Technique: Early-dynamic PET/CT of the endovascular prosthesis is performed for 180 seconds immediately after intravenous injection of F-18-fluorodeoxyglucose. Data are reconstructed in variable time frames (time periods after tracer injection) to visualize the arterial anatomy and are displayed as PET angiography or fused with CT images. Images are evaluated in view of vascular abnormalities, graft configuration, and tracer accumulation in the aneurysm sac. Whole-body PET/CT is performed 90 to 120 minutes after tracer injection. Conclusion: This protocol for early-dynamic PET/CT and PET angiography has the potential to evaluate vascular diseases, including the diagnosis of complications after endovascular procedures.
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Horikoshi, T., H. Ikegawa, M. Uchida, T. Takahashi, A. Watanabe, and T. Umeda. "Tracer Clearance in Radionuclide Cisternography in Patients with Spontaneous Intracranial Hypotension." Cephalalgia 26, no. 8 (August 2006): 1010–15. http://dx.doi.org/10.1111/j.1468-2982.2006.01152.x.
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We semiquantitatively analysed radionuclide cisternography in three patients with spontaneous cerebrospinal fluid (CSF) leakage diagnosed by typical symptoms and magnetic resonance imaging findings before and several months after treatment with epidural blood patch. Radioactivity in the whole CSF space was measured immediately after and at 1, 5, 7 and 24 h after intrathecal injection of 111In-diethylenetriaminepentaacetic acid (DTPA). Initial findings included the vague appearance of leakage in the thoracic spine in two patients, early bladder filling at 1 h in one and a lack of tracer filling into the high cranial convexity in all three. The radioactivity count rapidly decreased within several hours after injection and reached 20± of the initial value at 24 h. In contrast, no rapid decrease was observed after treatment and more than 50± of tracer remained at 24 h after injection. Semiquantitative analysis of tracer clearance may provide additional information in the diagnosis of CSF leakage, especially with no obvious qualitative findings.
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Geng, Abdollahi-Nasab, An, Chen, Lee, and Boufadel. "High Pressure Injection of Chemicals in a Gravel Beach." Processes 7, no. 8 (August 8, 2019): 525. http://dx.doi.org/10.3390/pr7080525.
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The remediation of beaches contaminated with oil includes the application of surfactants and/or the application of amendments to enhance oil biodegradation (i.e., bioremediation). This study focused on evaluating the practicability of the high pressure injection (HPI) of dissolved chemicals into the subsurface of a lentic Alaskan beach subjected to a 5 m tidal range. A conservative tracer, lithium, in a lithium bromide (LiBr) solution, was injected into the beach at 1.0 m depth near the mid-tide line. The flow rate was varied between 1.0 and 1.5 L/min, and the resulting injection pressure varied between 3 m and 6 m of water. The concentration of the injected tracer was measured from four surrounding monitoring wells at multiple depths. The HPI associated with a flow rate of 1.5 L/min resulted in a Darcy flux in the cross-shore direction at 1.15 × 10−5 m/s compared to that of 7.5 × 10−6 m/s under normal conditions. The HPI, thus, enhanced the hydraulic conveyance of the beach. The results revealed that the tracer plume dispersed an area of ~12 m2 within 24 h. These results suggest that deep injection of solutions into a gravel beach is a viable approach for remediating beaches.
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Morris, Evan D., Nathaniel M. Alpert, and Alan J. Fischman. "Comparison of Two Compartmental Models for Describing Receptor Ligand Kinetics and Receptor Availability in Multiple Injection PET Studies." Journal of Cerebral Blood Flow & Metabolism 16, no. 5 (September 1996): 841–53. http://dx.doi.org/10.1097/00004647-199609000-00009.
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The goal of research with receptor ligands and PET is the characterization of an in vivo system that measures rates of association and dissociation of a ligand-receptor complex and the density of available binding sites. It has been suggested that multiple injection studies of radioactive ligand are more likely to identify model parameters than are single injection studies. Typically, at least one of the late injections is at a low specific activity (SA), so that part of the positron emission tomography (PET) curve reflects ligand dissociation. Low SA injections and the attendant reductions in receptor availability, however, may violate tracer kinetic assumptions, namely, tracer may no longer be in steady state with the total (labeled and unlabeled) ligand. Tissue response becomes critically dependent on the dose of total ligand, and an accurate description of the cold ligand in the tissue is needed to properly model the system. Two alternative models have been applied to the receptor modeling problem, which reduces to describing the time-varying number of available receptor sites. The first ( Huang et al., 1989 ) contains only compartments for the hot ligand, ‘hot only’ (HO), but indirectly accounts for the action of cold ligand at receptor sites via SA. The second stipulates separate compartments for the hot and cold ligands, ‘hot and cold’ (HC), thus explicitly calculating available number of receptors. We examined these models and contrasted their abilities to predict PET activity, receptor availability, and SA in each tissue compartment. For multiple injection studies, the models consistently predicted different PET activities—especially following the third injection. Only for very high rate constants were the models identical for multiple injections. In one case, simulated PET curves were quite similar, but discrepancies appeared in predictions of receptor availability. The HO model predicted nonphysiological changes in the availability of receptor sites and introduced errors of 30–60% into estimates of B′max for test data. We, therefore, strongly recommend the use of the HC model for all analyses of multiple injection PET studies.
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Mahieu, Rutger, Josanne S. de Maar, Eliane R. Nieuwenhuis, Roel Deckers, Chrit Moonen, Lejla Alic, Bennie ten Haken, Bart de Keizer, and Remco de Bree. "New Developments in Imaging for Sentinel Lymph Node Biopsy in Early-Stage Oral Cavity Squamous Cell Carcinoma." Cancers 12, no. 10 (October 20, 2020): 3055. http://dx.doi.org/10.3390/cancers12103055.
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Sentinel lymph node biopsy (SLNB) is a diagnostic staging procedure that aims to identify the first draining lymph node(s) from the primary tumor, the sentinel lymph nodes (SLN), as their histopathological status reflects the histopathological status of the rest of the nodal basin. The routine SLNB procedure consists of peritumoral injections with a technetium-99m [99mTc]-labelled radiotracer followed by lymphoscintigraphy and SPECT-CT imaging. Based on these imaging results, the identified SLNs are marked for surgical extirpation and are subjected to histopathological assessment. The routine SLNB procedure has proven to reliably stage the clinically negative neck in early-stage oral squamous cell carcinoma (OSCC). However, an infamous limitation arises in situations where SLNs are located in close vicinity of the tracer injection site. In these cases, the hotspot of the injection site can hide adjacent SLNs and hamper the discrimination between tracer injection site and SLNs (shine-through phenomenon). Therefore, technical developments are needed to bring the diagnostic accuracy of SLNB for early-stage OSCC to a higher level. This review evaluates novel SLNB imaging techniques for early-stage OSCC: MR lymphography, CT lymphography, PET lymphoscintigraphy and contrast-enhanced lymphosonography. Furthermore, their reported diagnostic accuracy is described and their relative merits, disadvantages and potential applications are outlined.