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Sample records for transfer cest imaging

  1. Rapid and quantitative chemical exchange saturation transfer (CEST) imaging with magnetic resonance fingerprinting (MRF).

    Science.gov (United States)

    Cohen, Ouri; Huang, Shuning; McMahon, Michael T; Rosen, Matthew S; Farrar, Christian T

    2018-05-13

    To develop a fast magnetic resonance fingerprinting (MRF) method for quantitative chemical exchange saturation transfer (CEST) imaging. We implemented a CEST-MRF method to quantify the chemical exchange rate and volume fraction of the N α -amine protons of L-arginine (L-Arg) phantoms and the amide and semi-solid exchangeable protons of in vivo rat brain tissue. L-Arg phantoms were made with different concentrations (25-100 mM) and pH (pH 4-6). The MRF acquisition schedule varied the saturation power randomly for 30 iterations (phantom: 0-6 μT; in vivo: 0-4 μT) with a total acquisition time of ≤2 min. The signal trajectories were pattern-matched to a large dictionary of signal trajectories simulated using the Bloch-McConnell equations for different combinations of exchange rate, exchangeable proton volume fraction, and water T 1 and T 2 relaxation times. The chemical exchange rates of the N α -amine protons of L-Arg were significantly (P exchange using saturation power method. Similarly, the L-Arg concentrations determined using MRF were significantly (P exchange rate was well fit (R 2  = 0.9186) by a base catalyzed exchange model. The amide proton exchange rate measured in rat brain cortex (34.8 ± 11.7 Hz) was in good agreement with that measured previously with the water exchange spectroscopy method (28.6 ± 7.4 Hz). The semi-solid proton volume fraction was elevated in white (12.2 ± 1.7%) compared to gray (8.1 ± 1.1%) matter brain regions in agreement with previous magnetization transfer studies. CEST-MRF provides a method for fast, quantitative CEST imaging. © 2018 International Society for Magnetic Resonance in Medicine.

  2. Chemical exchange saturation transfer (CEST) MR technique for in-vivo liver imaging at 3.0 tesla

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shu-Zhong; Deng, Min; Wang, Yi-Xiang J. [Chinese University of Hong Kong, Prince of Wales Hospital, Department of Imaging and Interventional Radiology, Faculty of Medicine (China); Yuan, Jing [Hong Kong Sanatorium and Hospital, Medical Physics and Research Department, Happy Valley, Hong Kong (China); Wei, Juan [Philips Healthcare Asia, Shanghai (China); Zhou, Jinyuan [Johns Hopkins University, Department of Radiology, Baltimore, MD (United States); Kennedy Krieger Institute, F.M. Kirby Research Center for Functional Brain Imaging, Baltimore, MD (United States)

    2016-06-15

    To evaluate Chemical Exchange Saturation Transfer (CEST) MRI for liver imaging at 3.0-T. Images were acquired at offsets (n = 41, increment = 0.25 ppm) from -5 to 5 ppm using a TSE sequence with a continuous rectangular saturation pulse. Amide proton transfer-weighted (APTw) and GlycoCEST signals were quantified as the asymmetric magnetization transfer ratio (MTR{sub asym}) at 3.5 ppm and the total MTR{sub asym} integrated from 0.5 to 1.5 ppm, respectively, from the corrected Z-spectrum. Reproducibility was assessed for rats and humans. Eight rats were devoid of chow for 24 hours and scanned before and after fasting. Eleven rats were scanned before and after one-time CCl4 intoxication. For reproducibility, rat liver APTw and GlycoCEST measurements had 95 % limits of agreement of -1.49 % to 1.28 % and -0.317 % to 0.345 %. Human liver APTw and GlycoCEST measurements had 95 % limits of agreement of -0.842 % to 0.899 % and -0.344 % to 0.164 %. After 24 hours, fasting rat liver APTw and GlycoCEST signals decreased from 2.38 ± 0.86 % to 0.67 ± 1.12 % and from 0.34 ± 0.26 % to -0.18 ± 0.37 % respectively (p < 0.05). After CCl4 intoxication rat liver APTw and GlycoCEST signals decreased from 2.46 ± 0.48 % to 1.10 ± 0.77 %, and from 0.34 ± 0.23 % to -0.16 ± 0.51 % respectively (p < 0.05). CEST liver imaging at 3.0-T showed high sensitivity for fasting as well as CCl4 intoxication. (orig.)

  3. Chemical exchange saturation transfer (CEST) MR technique for in-vivo liver imaging at 3.0 tesla.

    Science.gov (United States)

    Chen, Shu-Zhong; Yuan, Jing; Deng, Min; Wei, Juan; Zhou, Jinyuan; Wáng, Yì-Xiáng J

    2016-06-01

    To evaluate Chemical Exchange Saturation Transfer (CEST) MRI for liver imaging at 3.0-T. Images were acquired at offsets (n = 41, increment = 0.25 ppm) from -5 to 5 ppm using a TSE sequence with a continuous rectangular saturation pulse. Amide proton transfer-weighted (APTw) and GlycoCEST signals were quantified as the asymmetric magnetization transfer ratio (MTRasym) at 3.5 ppm and the total MTRasym integrated from 0.5 to 1.5 ppm, respectively, from the corrected Z-spectrum. Reproducibility was assessed for rats and humans. Eight rats were devoid of chow for 24 hours and scanned before and after fasting. Eleven rats were scanned before and after one-time CCl4 intoxication. For reproducibility, rat liver APTw and GlycoCEST measurements had 95 % limits of agreement of -1.49 % to 1.28 % and -0.317 % to 0.345 %. Human liver APTw and GlycoCEST measurements had 95 % limits of agreement of -0.842 % to 0.899 % and -0.344 % to 0.164 %. After 24 hours, fasting rat liver APTw and GlycoCEST signals decreased from 2.38 ± 0.86 % to 0.67 ± 1.12 % and from 0.34 ± 0.26 % to -0.18 ± 0.37 % respectively (p 3.0-T showed high sensitivity for fasting as well as CCl4 intoxication. • CEST MRI of in-vivo liver was demonstrated at clinical 3 T field strength. • After 24-hour fasting, rat liver APTw and GlycoCEST signals decreased significantly. • After CCl4 intoxication both rat liver APTw and GlycoCEST signals decreased significantly. • Good scan-rescan reproducibility of liver CEST MRI was shown in healthy volunteers.

  4. Nuts and Bolts of CEST MR imaging

    Science.gov (United States)

    Liu, Guanshu; Song, Xiaolei; Chan, Kannie W.Y.

    2013-01-01

    Chemical Exchange Saturation Transfer (CEST) has emerged as a novel MRI contrast mechanism that is well suited for molecular imaging studies. This new mechanism can be used to detect small amounts of contrast agent through saturation of rapidly exchanging protons on these agents, allowing a wide range of applications. CEST technology has a number of indispensable features, such as the possibility of simultaneous detection of multiple “colors” of agents and detecting changes in their environment (e.g. pH, metabolites, etc) through MR contrast. Currently a large number of new imaging schemes and techniques have been developed to improve the temporal resolution and specificity and to correct the influence of B0 and B1 inhomogeneities. In this review, the techniques developed over the last decade have been summarized with the different imaging strategies and post-processing methods discussed from a practical point of view including describing their relative merits for detecting CEST agents. The goal of the present work is to provide the reader with a fundamental understanding of the techniques developed, and to provide guidance to help refine future applications of this technology. This review is organized into three main sections: Basics of CEST Contrast, Implementation, Post-Processing, and also includes a brief Introduction section and Summary. The Basics of CEST Contrast section contains a description of the relevant background theory for saturation transfer and frequency labeled transfer, and a brief discussion of methods to determine exchange rates. The Implementation section contains a description of the practical considerations in conducting CEST MRI studies, including choice of magnetic field, pulse sequence, saturation pulse, imaging scheme, and strategies to separate MT and CEST. The Post-Processing section contains a description of the typical image processing employed for B0/B1 correction, Z-spectral interpolation, frequency selective detection, and

  5. Quantification of iopamidol multi-site chemical exchange properties for ratiometric chemical exchange saturation transfer (CEST) imaging of pH

    International Nuclear Information System (INIS)

    Sun, Phillip Zhe; Longo, Dario Livio; Hu, Wei; Xiao, Gang; Wu, Renhua

    2014-01-01

    pH-sensitive chemical exchange saturation transfer (CEST) MRI holds great promise for in vivo applications. However, the CEST effect depends on not only exchange rate and hence pH, but also on the contrast agent concentration, which must be determined independently for pH quantification. Ratiometric CEST MRI normalizes the concentration effect by comparing CEST measurements of multiple labile protons to simplify pH determination. Iopamidol, a commonly used x-ray contrast agent, has been explored as a ratiometric CEST agent for imaging pH. However, iopamidol CEST properties have not been solved, determination of which is important for optimization and quantification of iopamidol pH imaging. Our study numerically solved iopamidol multi-site pH-dependent chemical exchange properties. We found that iopamidol CEST MRI is suitable for measuring pH between 6 and 7.5 despite that T 1 and T 2 measurements varied substantially with pH and concentration. The pH MRI precision decreased with pH and concentration. The standard deviation of pH determined from MRI was 0.2 and 0.4 pH unit for 40 and 20 mM iopamidol solution of pH 6, and it improved to be less than 0.1 unit for pH above 7. Moreover, we determined base-catalyzed chemical exchange for 2-hydrooxypropanamido (k sw = 1.2*10 pH−4.1 ) and amide (k sw = 1.2*10 pH−4.6 ) protons that are statistically different from each other (P < 0.01, ANCOVA), understanding of which should help guide in vivo translation of iopamidol pH imaging. (paper)

  6. A lanthanide complex with dual biosensing properties: CEST (chemical exchange saturation transfer) and BIRDS (biosensor imaging of redundant deviation in shifts) with europium DOTA-tetraglycinate.

    Science.gov (United States)

    Coman, Daniel; Kiefer, Garry E; Rothman, Douglas L; Sherry, A Dean; Hyder, Fahmeed

    2011-12-01

    Responsive contrast agents (RCAs) composed of lanthanide(III) ion (Ln3R) complexes with a variety of1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA4S) derivatives have shown great potential as molecular imaging agents for MR. A variety of LnDOTA–tetraamide complexes have been demonstrated as RCAs for molecular imaging using chemical exchange saturation transfer (CEST). The CEST method detects proton exchange between bulk water and any exchangeable sites on the ligand itself or an inner sphere of bound water that is shifted by a paramagnetic Ln3R ion bound in the core of the macrocycle. It has also been shown that molecular imaging is possible when the RCA itself is observed (i.e. not its effect on bulk water) using a method called biosensor imaging of redundant deviation in shifts (BIRDS). The BIRDS method utilizes redundant information stored in the nonexchangeable proton resonances emanating from the paramagnetic RCA for ambient factors such as temperature and/or pH.Thus, CEST and BIRDS rely on exchangeable and nonexchangeable protons, respectively, for biosensing. We posited that it would be feasible to combine these two biosensing features into the same RCA (i.e. dual CEST and BIRDS properties). A complex between europium(III) ion (Eu3R) and DOTA–tetraglycinate [DOTA–(gly)S4] was used to demonstrate that its CEST characteristics are preserved, while its BIRDS properties are also detectable. The in vitro temperature sensitivity of EuDOTA–(gly)S4 was used to show that qualitative MR contrast with CEST can be calibrated using quantitative MR mapping with BIRDS, thereby enabling quantitative molecular imaging at high spatial resolution.

  7. EXCI-CEST: Exploiting pharmaceutical excipients as MRI-CEST contrast agents for tumor imaging.

    Science.gov (United States)

    Longo, Dario Livio; Moustaghfir, Fatima Zzahra; Zerbo, Alexandre; Consolino, Lorena; Anemone, Annasofia; Bracesco, Martina; Aime, Silvio

    2017-06-15

    Chemical Exchange Saturation Transfer (CEST) approach is a novel tool within magnetic resonance imaging (MRI) that allows visualization of molecules possessing exchangeable protons with water. Many molecules, employed as excipients for the formulation of finished drug products, are endowed with hydroxyl, amine or amide protons, thus can be exploitable as MRI-CEST contrast agents. Their high safety profiles allow them to be injected at very high doses. Here we investigated the MRI-CEST properties of several excipients (ascorbic acid, sucrose, N-acetyl-d-glucosamine, meglumine and 2-pyrrolidone) and tested them as tumor-detecting agents in two different murine tumor models (breast and melanoma cancers). All the investigated molecules showed remarkable CEST contrast upon i.v. administration in the range 1-3ppm according to the type of mobile proton groups. A marked increase of CEST contrast was observed in tumor regions up to 30min post injection. The combination of marked tumor contrast enhancement and lack of toxicity make these molecules potential candidates for the diagnosis of tumors within the MRI-CEST approach. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. R1 correction in amide proton transfer imaging: indication of the influence of transcytolemmal water exchange on CEST measurements.

    Science.gov (United States)

    Li, Hua; Li, Ke; Zhang, Xiao-Yong; Jiang, Xiaoyu; Zu, Zhongliang; Zaiss, Moritz; Gochberg, Daniel F; Gore, John C; Xu, Junzhong

    2015-12-01

    Amide proton transfer (APT) imaging may potentially detect mobile proteins/peptides non-invasively in vivo, but its specificity may be reduced by contamination from other confounding effects such as asymmetry of non-specific magnetization transfer (MT) effects and spin-lattice relaxation with rate R1 (=1/T1). Previously reported spillover, MT and R1 correction methods were based on a two-pool model, in which the existence of multiple water compartments with heterogeneous relaxation properties in real tissues was ignored. Such simple models may not adequately represent real tissues, and thus such corrections may be unreliable. The current study investigated the effectiveness and accuracy of correcting for R1 in APT imaging via simulations and in vivo experiments using tumor-bearing rats subjected to serial injections of Gd-DTPA that produced different tissue R1 values in regions of blood-brain-barrier breakdown. The results suggest that conventional measurements of APT contrast (such as APT* and MTRasym ) may be significantly contaminated by R1 variations, while the R1 -corrected metric AREX* was found to be relatively unaffected by R1 changes over a broad range (0.4-1 Hz). Our results confirm the importance of correcting for spin-lattice relaxation effects in quantitative APT imaging, and demonstrate the reliability of using the observed tissue R1 for corrections to obtain more specific and accurate measurements of APT contrast in vivo. The results also indicate that, due to relatively fast transcytolemmal water exchange, the influence of intra- and extracellular water compartments on CEST measurements with seconds long saturation time may be ignored in tumors. Copyright © 2015 John Wiley & Sons, Ltd.

  9. Transfer Rate Edited experiment for the selective detection of Chemical Exchange via Saturation Transfer (TRE-CEST)

    Science.gov (United States)

    Friedman, Joshua I.; Xia, Ding; Regatte, Ravinder R.; Jerschow, Alexej

    2015-07-01

    Chemical Exchange Saturation Transfer (CEST) magnetic resonance experiments have become valuable tools in magnetic resonance for the detection of low concentration solutes with far greater sensitivity than direct detection methods. Accurate measures of rates of chemical exchange provided by CEST are of particular interest to biomedical imaging communities where variations in chemical exchange can be related to subtle variations in biomarker concentration, temperature and pH within tissues using MRI. Despite their name, however, traditional CEST methods are not truly selective for chemical exchange and instead detect all forms of magnetization transfer including through-space NOE. This ambiguity crowds CEST spectra and greatly complicates subsequent data analysis. We have developed a Transfer Rate Edited CEST experiment (TRE-CEST) that uses two different types of solute labeling in order to selectively amplify signals of rapidly exchanging proton species while simultaneously suppressing 'slower' NOE-dominated magnetization transfer processes. This approach is demonstrated in the context of both NMR and MRI, where it is used to detect the labile amide protons of proteins undergoing chemical exchange (at rates ⩾ 30 s-1) while simultaneously eliminating signals originating from slower (∼5 s-1) NOE-mediated magnetization transfer processes. TRE-CEST greatly expands the utility of CEST experiments in complex systems, and in-vivo, in particular, where it is expected to improve the quantification of chemical exchange and magnetization transfer rates while enabling new forms of imaging contrast.

  10. Transfer Rate Edited experiment for the selective detection of Chemical Exchange via Saturation Transfer (TRE-CEST).

    Science.gov (United States)

    Friedman, Joshua I; Xia, Ding; Regatte, Ravinder R; Jerschow, Alexej

    2015-07-01

    Chemical Exchange Saturation Transfer (CEST) magnetic resonance experiments have become valuable tools in magnetic resonance for the detection of low concentration solutes with far greater sensitivity than direct detection methods. Accurate measures of rates of chemical exchange provided by CEST are of particular interest to biomedical imaging communities where variations in chemical exchange can be related to subtle variations in biomarker concentration, temperature and pH within tissues using MRI. Despite their name, however, traditional CEST methods are not truly selective for chemical exchange and instead detect all forms of magnetization transfer including through-space NOE. This ambiguity crowds CEST spectra and greatly complicates subsequent data analysis. We have developed a Transfer Rate Edited CEST experiment (TRE-CEST) that uses two different types of solute labeling in order to selectively amplify signals of rapidly exchanging proton species while simultaneously suppressing 'slower' NOE-dominated magnetization transfer processes. This approach is demonstrated in the context of both NMR and MRI, where it is used to detect the labile amide protons of proteins undergoing chemical exchange (at rates⩾30s(-1)) while simultaneously eliminating signals originating from slower (∼5s(-1)) NOE-mediated magnetization transfer processes. TRE-CEST greatly expands the utility of CEST experiments in complex systems, and in-vivo, in particular, where it is expected to improve the quantification of chemical exchange and magnetization transfer rates while enabling new forms of imaging contrast. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Chemical Exchange Saturation Transfer (CEST): what is in a name and what isn’t?

    Science.gov (United States)

    van Zijl, Peter C.M.; Yadav, Nirbhay N.

    2011-01-01

    Chemical exchange saturation transfer (CEST) imaging is a relatively new MRI contrast approach in which exogenous or endogenous compounds containing either exchangeable protons or exchangeable molecules are selectively saturated and, after transfer of this saturation, detected indirectly through the water signal with enhanced sensitivity. The focus of this review is on basic MR principles underlying CEST and similarities to and differences with conventional magnetization transfer contrast (MTC). In CEST MRI, transfer of magnetization is studied in mobile compounds instead of semisolids. Similar to MTC, CEST has contributions of both chemical exchange and dipolar cross-relaxation, but the latter can often be neglected if exchange is fast. Contrary to MTC, CEST imaging requires sufficiently slow exchange on the MR time scale to allow selective irradiation of the protons of interest. As a consequence, magnetic labeling is not limited to radio-frequency saturation but can be expanded with slower frequency-selective approaches such as inversion, gradient dephasing and frequency labeling. The basic theory, design criteria, and experimental issues for exchange transfer imaging are discussed. A new classification for CEST agents based on exchange type is proposed. The potential of this young field is discussed, especially with respect to in vivo application and translation to humans. PMID:21337419

  12. SU-E-J-225: CEST Imaging in Head and Neck Cancer Patients

    International Nuclear Information System (INIS)

    Wang, J; Hwang, K; Fuller, C; Mohamed, A; Ding, Y; Frank, S; Hazle, J; Zhou, J

    2015-01-01

    Purpose: Chemical Exchange Saturation Transfer (CEST) imaging is an MRI technique enables the detection and imaging of metabolically active compounds in vivo. It has been used to differentiate tumor types and metabolic characteristics. Unlike PET/CT,CEST imaging does not use isotopes so it can be used on patient repeatedly. This study is to report the preliminary results of CEST imaging in Head and Neck cancer (HNC) patients. Methods: A CEST imaging sequence and the post-processing software was developed on a 3T clinical MRI scanner. Ten patients with Human papilloma virus positive oropharyngeal cancer were imaged in their immobilized treatment position. A 5 mm slice CEST image was acquired (128×128, FOV=20∼24cm) to encompass the maximum dimension of tumor. Twenty-nine off-set frequencies (from −7.8ppm to +7.8 ppm) were acquired to obtain the Z-spectrum. Asymmetry analysis was used to extract the CEST contrasts. ROI at the tumor, node and surrounding tissues were measured. Results: CEST images were successfully acquired and Zspectrum asymmetry analysis demonstrated clear CEST contrasts in tumor as well as the surrounding tissues. 3∼5% CEST contrast in the range of 1 to 4 ppm was noted in tumor as well as grossly involved nodes. Injection of glucose produced a marked increase of CEST contrast in tumor region (∼10%). Motion and pulsation artifacts tend to smear the CEST contrast, making the interpretation of the image contrast difficult. Field nonuniformity, pulsation in blood vesicle and susceptibility artifacts caused by air cavities were also problematic for CEST imaging. Conclusion: We have demonstrated successful CEST acquisition and Z-spectrum reconstruction on HNC patients with a clinical scanner. MRI acquisition in immobilized treatment position is critical for image quality as well as the success of CEST image acquisition. CEST images provide novel contrast of metabolites in HNC and present great potential in the pre- and post-treatment assessment

  13. SU-E-J-225: CEST Imaging in Head and Neck Cancer Patients

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J; Hwang, K; Fuller, C; Mohamed, A; Ding, Y; Frank, S; Hazle, J; Zhou, J [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: Chemical Exchange Saturation Transfer (CEST) imaging is an MRI technique enables the detection and imaging of metabolically active compounds in vivo. It has been used to differentiate tumor types and metabolic characteristics. Unlike PET/CT,CEST imaging does not use isotopes so it can be used on patient repeatedly. This study is to report the preliminary results of CEST imaging in Head and Neck cancer (HNC) patients. Methods: A CEST imaging sequence and the post-processing software was developed on a 3T clinical MRI scanner. Ten patients with Human papilloma virus positive oropharyngeal cancer were imaged in their immobilized treatment position. A 5 mm slice CEST image was acquired (128×128, FOV=20∼24cm) to encompass the maximum dimension of tumor. Twenty-nine off-set frequencies (from −7.8ppm to +7.8 ppm) were acquired to obtain the Z-spectrum. Asymmetry analysis was used to extract the CEST contrasts. ROI at the tumor, node and surrounding tissues were measured. Results: CEST images were successfully acquired and Zspectrum asymmetry analysis demonstrated clear CEST contrasts in tumor as well as the surrounding tissues. 3∼5% CEST contrast in the range of 1 to 4 ppm was noted in tumor as well as grossly involved nodes. Injection of glucose produced a marked increase of CEST contrast in tumor region (∼10%). Motion and pulsation artifacts tend to smear the CEST contrast, making the interpretation of the image contrast difficult. Field nonuniformity, pulsation in blood vesicle and susceptibility artifacts caused by air cavities were also problematic for CEST imaging. Conclusion: We have demonstrated successful CEST acquisition and Z-spectrum reconstruction on HNC patients with a clinical scanner. MRI acquisition in immobilized treatment position is critical for image quality as well as the success of CEST image acquisition. CEST images provide novel contrast of metabolites in HNC and present great potential in the pre- and post-treatment assessment

  14. Development of NMR imaging using CEST agents: application to brain tumor in a rodent model

    International Nuclear Information System (INIS)

    Flament, J.

    2012-01-01

    The study aimed at developing saturation transfer imaging of lipoCEST contrast agents for the detection of angiogenesis in a U87 mouse brain tumor model. A lipoCEST with a sensitivity threshold of 100 pM in vitro was optimized in order to make it compatible with CEST imaging in vivo. Thanks to the development of an experimental setup dedicated to CEST imaging, we evaluated lipoCEST to detect specifically tumor angiogenesis. We demonstrated for the first time that lipoCEST visualization was feasible in vivo in a mouse brain after intravenous injection. Moreover, the integrin α v β 3 over expressed during tumor angiogenesis can be specifically targeted using a functionalized lipoCEST with RGD peptide. The specific association between the RGD-lipoCEST and its target α v β 3 was confirmed by immunohistochemical data and fluorescence microscopy. Finally, in order to tend to a molecular imaging protocol by CEST-MRI, we developed a quantification tool of lipoCEST contrast agents. This tool is based on modeling of proton exchange processes in vivo. By taking into account both B0 and B1 fields inhomogeneities which can dramatically alter CEST contrast, we showed that the accuracy of our quantification tool was 300 pM in vitro. The tool was applied on in vivo data acquired on the U87 mouse model and the maximum concentration of RGD-lipoCEST linked to their molecular targets was evaluated to 1.8 nM. (author) [fr

  15. Lanthanide ion (III) complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminophosphonate for dual biosensing of pH with chemical exchange saturation transfer (CEST) and biosensor imaging of redundant deviation in shifts (BIRDS).

    Science.gov (United States)

    Huang, Yuegao; Coman, Daniel; Ali, Meser M; Hyder, Fahmeed

    2015-01-01

    Relaxivity-based magnetic resonance of phosphonated ligands chelated with gadolinium (Gd(3+)) shows promise for pH imaging. However instead of monitoring the paramagnetic effect of lanthanide complexes on the relaxivity of water protons, biosensor (or molecular) imaging with magnetic resonance is also possible by detecting either the nonexchangeable or the exchangeable protons on the lanthanide complexes themselves. The nonexchangeable protons (e.g. -CHx, where 3 ≥ x ≥ 1) are detected using a three-dimensional chemical shift imaging method called biosensor imaging of redundant deviation in shifts (BIRDS), whereas the exchangeable protons (e.g. -OH or -NHy , where 2 ≥ y ≥ 1) are measured with chemical exchange saturation transfer (CEST) contrast. Here we tested the feasibility of BIRDS and CEST for pH imaging of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminophosphonate (DOTA-4AmP(8-)) chelated with thulium (Tm(3+) ) and ytterbium (Yb(3+)). BIRDS and CEST experiments show that both complexes are responsive to pH and temperature changes. Higher pH and temperature sensitivities are obtained with BIRDS for either complex when using the chemical shift difference between two proton resonances vs using the chemical shift of a single proton resonance, thereby eliminating the need to use water resonance as reference. While CEST contrast for both agents is linearly dependent on pH within a relatively large range (i.e. 6.3-7.9), much stronger CEST contrast is obtained with YbDOTA-4AmP(5-) than with TmDOTA-4AmP(5-). In addition, we demonstrate the prospect of using BIRDS to calibrate CEST as new platform for quantitative pH imaging. Copyright © 2014 John Wiley & Sons, Ltd.

  16. Simultaneous pH-sensitive and oxygen-sensitive MRI of human gliomas at 3 T using multi-echo amine proton chemical exchange saturation transfer spin-and-gradient echo echo-planar imaging (CEST-SAGE-EPI).

    Science.gov (United States)

    Harris, Robert J; Yao, Jingwen; Chakhoyan, Ararat; Raymond, Catalina; Leu, Kevin; Liau, Linda M; Nghiemphu, Phioanh L; Lai, Albert; Salamon, Noriko; Pope, Whitney B; Cloughesy, Timothy F; Ellingson, Benjamin M

    2018-04-06

    To introduce a new pH-sensitive and oxygen-sensitive MRI technique using amine proton CEST echo spin-and-gradient echo (SAGE) EPI (CEST-SAGE-EPI). pH-weighting was obtained using CEST estimations of magnetization transfer ratio asymmetry (MTR asym ) at 3 ppm, and oxygen-weighting was obtained using R2' measurements. Glutamine concentration, pH, and relaxation rates were varied in phantoms to validate simulations and estimate relaxation rates. The values of MTR asym and R2' in normal-appearing white matter, T 2 hyperintensity, contrast enhancement, and macroscopic necrosis were measured in 47 gliomas. Simulation and phantom results confirmed an increase in MTR asym with decreasing pH. The CEST-SAGE-EPI estimates of R 2 , R2*, and R2' varied linearly with gadolinium diethylenetriamine penta-acetic acid concentration (R 2  = 6.2 mM -1 ·sec -1 and R2* = 6.9 mM -1 ·sec -1 ). The CEST-SAGE-EPI and Carr-Purcell-Meiboom-Gill estimates of R 2 (R 2  = 0.9943) and multi-echo gradient-echo estimates of R2* (R 2  = 0.9727) were highly correlated. T 2 lesions had lower R2' and higher MTR asym compared with normal-appearing white matter, suggesting lower hypoxia and high acidity, whereas contrast-enhancement tumor regions had elevated R2' and MTR asym , indicating high hypoxia and acidity. The CEST-SAGE-EPI technique provides simultaneous pH-sensitive and oxygen-sensitive image contrasts for evaluation of the brain tumor microenvironment. Advantages include fast whole-brain acquisition, in-line B 0 correction, and simultaneous estimation of CEST effects, R 2 , R2*, and R2' at 3 T. © 2018 International Society for Magnetic Resonance in Medicine.

  17. Breast Cancer Redox Heterogeneity Detectable with Chemical Exchange Satruation Transfer (CEST) MRI

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    Cai, Kejia; Xu, He N.; Singh, Anup; Moon, Lily; Haris, Mohammad; Reddy, Ravinder; Li, Lin

    2014-01-01

    Purpose Tissue redox state is an important mediator of various biological processes in health and diseases such as cancer. Previously, we discovered that the mitochondrial redox state of ex vivo tissues detected by redox scanning (an optical imaging method) revealed interesting tumor redox state heterogeneity that could differentiate tumor aggressiveness. Because the noninvasive chemical exchange saturation transfer (CEST) MRI can probe the proton transfer and generate contrasts from endogenous metabolites, we aim to investigate if the in vivo CEST contrast is sensitive to proton transfer of the redox reactions so as to reveal the tissue redox states in breast cancer animal models. Procedures CEST MRI has been employed to characterize tumor metabolic heterogeneity and correlated with the redox states measured by the redox scanning in two human breast cancer mouse xenograft models, MDA-MB-231 and MCF-7. The possible biological mechanism on the correlation between the two imaging modalities was further investigated by phantom studies where the reductants and the oxidants of the representative redox reactions were measured. Results The CEST contrast is found linearly correlated with NADH concentration and the NADH redox ratio with high statistical significance, where NADH is the reduced form of nicotinamide adenine dinucleotide. The phantom studies showed that the reductants of the redox reactions have more CEST contrast than the corresponding oxidants, indicating that higher CEST effect corresponds to the more reduced redox state. Conclusions This preliminary study suggests that CEST MRI, once calibrated, might provide a novel noninvasive imaging surrogate for the tissue redox state and a possible diagnostic biomarker for breast cancer in the clinic. PMID:24811957

  18. Exchange-Mediated Contrast in CEST and Spin-Lock Imaging

    Science.gov (United States)

    Cobb, Jared Guthrie; Li, Ke; Xie, Jingping; Gochberg, Daniel F.; Gore, John C.

    2014-01-01

    PURPOSE Magnetic resonance images of biological media based on chemical exchange saturation transfer (CEST) show contrast that depends on chemical exchange between water and other protons. In addition, spin-lattice relaxation rates in the rotating frame (R1ρ) are also affected by exchange, especially at high fields, and can be exploited to provide novel, exchange-dependent contrast. Here, we evaluate and compare the factors that modulate the exchange contrast for these methods using simulations and experiments on simple, biologically relevant samples. METHODS Simulations and experimental measurements at 9.4T of rotating frame relaxation rate dispersion and CEST contrast were performed on solutions of macromolecules containing amide and hydroxyl exchanging protons. RESULTS The simulations and experimental measurements confirm that both CEST and R1ρ measurements depend on similar exchange parameters, but they manifest themselves differently in their effects on contrast. CEST contrast may be larger in the slow and intermediate exchange regimes for protons with large resonant frequency offsets (e.g. > 2ppm). Spin-locking techniques can produce larger contrast enhancement when resonant frequency offsets are small (exchange is in the intermediate to fast regime. The image contrasts scale differently with field strength, exchange rate and concentration. CONCLUSION CEST and R1ρ measurements provide different and somewhat complementary information about exchange in tissues. Whereas CEST can depict exchange of protons with specific chemical shifts, appropriate R1ρ dependent acquisitions can be employed to selectively portray protons of specific exchange rates. PMID:24239335

  19. Exchange-mediated contrast in CEST and spin-lock imaging.

    Science.gov (United States)

    Cobb, Jared Guthrie; Li, Ke; Xie, Jingping; Gochberg, Daniel F; Gore, John C

    2014-01-01

    Magnetic resonance images of biological media based on chemical exchange saturation transfer (CEST) show contrast that depends on chemical exchange between water and other protons. In addition, spin-lattice relaxation rates in the rotating frame (R1ρ) are also affected by exchange, especially at high fields, and can be exploited to provide novel, exchange-dependent contrast. Here, we evaluate and compare the factors that modulate the exchange contrast for these methods using simulations and experiments on simple, biologically relevant samples. Simulations and experimental measurements at 9.4 T of rotating frame relaxation rate dispersion and CEST contrast were performed on solutions of macromolecules containing amide and hydroxyl exchanging protons. The simulations and experimental measurements confirm that both CEST and R1ρ measurements depend on similar exchange parameters, but they manifest themselves differently in their effects on contrast. CEST contrast may be larger in the slow and intermediate exchange regimes for protons with large resonant frequency offsets (e.g. >2 ppm). Spin-locking techniques can produce larger contrast enhancement when resonant frequency offsets are small (exchange is in the intermediate-to-fast regime. The image contrasts scale differently with field strength, exchange rate and concentration. CEST and R1ρ measurements provide different and somewhat complementary information about exchange in tissues. Whereas CEST can depict exchange of protons with specific chemical shifts, appropriate R1ρ-dependent acquisitions can be employed to selectively portray protons of specific exchange rates. © 2013.

  20. Evaluation of the dependence of CEST-EPI measurement on repetition time, RF irradiation duty cycle and imaging flip angle for enhanced pH sensitivity

    International Nuclear Information System (INIS)

    Sun, Phillip Zhe; Lu Jie; Wu Yin; Xiao Gang; Wu Renhua

    2013-01-01

    Chemical exchange saturation transfer (CEST) is a magnetic resonance imaging (MRI) contrast mechanism that can detect dilute CEST agents and microenvironmental properties, with a host of promising applications. Experimental measurement of the CEST effect is complex, and depends on not only CEST agent concentration and exchange rate, but also experimental parameters such as RF irradiation amplitude and scheme. Although echo planar imaging (EPI) has been increasingly used for CEST MRI, the relationship between CEST effect and repetition time (TR), RF irradiation duty cycle (DC) and EPI flip angle (α) has not been fully evaluated and optimized to enhance CEST MRI sensitivity. In addition, our study evaluated gradient echo CEST-EPI by quantifying the CEST effect and its signal-to-noise ratio per unit time (SNR put ) as functions of TR, DC and α. We found that CEST effect increased with TR and DC but decreased with α. Importantly, we found that SNR put peaked at intermediate TRs of about twice the T 1 and α, at approximately 75°, and increased with RF DC. The simulation results were validated using a dual-pH creatine-gel CEST phantom. In summary, our study provides a useful framework for optimizing CEST MRI experiments. (note)

  1. Lanthanide ion (III) complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminophosphonate (DOTA-4AmP8−) for dual biosensing of pH with CEST (chemical exchange saturation transfer) and BIRDS (biosensor imaging of redundant deviation in shifts)

    Science.gov (United States)

    Huang, Yuegao; Coman, Daniel; Ali, Meser M.; Hyder, Fahmeed

    2014-01-01

    Relaxivity based magnetic resonance of phosphonated ligands chelated with gadolinium (Gd3+) shows promise for pH imaging. However instead of monitoring the paramagnetic effect of lanthanide complexes on the relaxivity of water protons, biosensor (or molecular) imaging with magnetic resonance is also possible by detecting either the non-exchangeable or the exchangeable protons on the lanthanide complexes themselves. The non-exchangeable protons (e.g., –CHx, where 3≥x≥1) are detected using a three-dimensional chemical shift imaging method called Biosensor Imaging of Redundant Deviation in Shifts (BIRDS), whereas the exchangeable protons (e.g., –OH or –NHy, where 2≥y≥1) are measured with Chemical Exchange Saturation Transfer (CEST) contrast. Here we tested the feasibility of BIRDS and CEST for pH imaging of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminophosphonate (DOTA-4AmP8−) chelated with thulium (Tm3+) and ytterbium (Yb3+). BIRDS and CEST experiments show that both complexes are responsive to pH and temperature changes. Higher pH and temperature sensitivities are obtained with BIRDS for either complex when using the chemical shift difference between two proton resonances vs. using the chemical shift of a single proton resonance, thereby eliminating the need to use water resonance as reference. While CEST contrast for both agents is linearly dependent on pH within a relatively large range (i.e., 6.3-7.9), much stronger CEST contrast is obtained with YbDOTA-4AmP5− than with TmDOTA-4AmP5−. In addition, we demonstrate the prospect of using BIRDS to calibrate CEST as new platform for quantitative pH imaging. PMID:24801742

  2. Quantitative chemical exchange saturation transfer (qCEST) MRI - omega plot analysis of RF-spillover-corrected inverse CEST ratio asymmetry for simultaneous determination of labile proton ratio and exchange rate.

    Science.gov (United States)

    Wu, Renhua; Xiao, Gang; Zhou, Iris Yuwen; Ran, Chongzhao; Sun, Phillip Zhe

    2015-03-01

    Chemical exchange saturation transfer (CEST) MRI is sensitive to labile proton concentration and exchange rate, thus allowing measurement of dilute CEST agent and microenvironmental properties. However, CEST measurement depends not only on the CEST agent properties but also on the experimental conditions. Quantitative CEST (qCEST) analysis has been proposed to address the limitation of the commonly used simplistic CEST-weighted calculation. Recent research has shown that the concomitant direct RF saturation (spillover) effect can be corrected using an inverse CEST ratio calculation. We postulated that a simplified qCEST analysis is feasible with omega plot analysis of the inverse CEST asymmetry calculation. Specifically, simulations showed that the numerically derived labile proton ratio and exchange rate were in good agreement with input values. In addition, the qCEST analysis was confirmed experimentally in a phantom with concurrent variation in CEST agent concentration and pH. Also, we demonstrated that the derived labile proton ratio increased linearly with creatine concentration (P analysis can simultaneously determine labile proton ratio and exchange rate in a relatively complex in vitro CEST system. Copyright © 2015 John Wiley & Sons, Ltd.

  3. Advantages of chemical exchange-sensitive spin-lock (CESL) over chemical exchange saturation transfer (CEST) for hydroxyl- and amine-water proton exchange studies.

    Science.gov (United States)

    Jin, Tao; Kim, Seong-Gi

    2014-11-01

    The chemical exchange (CE) rate of endogenous hydroxyl and amine protons with water is often comparable to the difference in their chemical shifts. These intermediate exchange processes have been imaged by the CE saturation transfer (CEST) approach with low-power and long-duration irradiation. However, the sensitivity is not optimal and, more importantly, the signal is contaminated by slow magnetization transfer processes. Here, the properties of CEST signals are compared with those of a CE-sensitive spin-lock (CESL) technique irradiating at the labile proton frequency. First, using a higher power and shorter irradiation in CE-MRI, we obtain: (i) an increased selectivity to faster CE rates via a higher sensitivity to faster CEs and a lower sensitivity to slower CEs and magnetization transfer processes; and (ii) a decreased in vivo asymmetric magnetization transfer contrast measured at ±15 ppm. The sensitivity gain of CESL over CEST is higher for a higher power and shorter irradiation. Unlike CESL, CEST signals oscillate at a very high power and short irradiation. Second, time-dependent CEST and CESL signals are well modeled by analytical solutions of CE-MRI with an asymmetric population approximation, which can be used for quantitative CE-MRI and validated by simulations of Bloch-McConnell equations and phantom experiments. Finally, the in vivo amine-water proton exchange contrast measured at 2.5 ppm with ω1 = 500 Hz is 18% higher in sensitivity for CESL than CEST at 9.4 T. Overall, CESL provides better exchange rate selectivity and sensitivity than CEST; therefore, CESL is more suitable for CE-MRI of intermediate exchange protons. Copyright © 2014 John Wiley & Sons, Ltd.

  4. Advantages of Chemical Exchange-Sensitive Spin-Lock (CESL) Over Saturation Transfer (CEST) for Hydroxyl- and Amine-Water Proton Exchange Studies

    Science.gov (United States)

    Jin, Tao; Kim, Seong-Gi

    2014-01-01

    The chemical exchange (CE) rate of endogenous hydroxyl and amine protons with water is often comparable to the difference in their chemical shifts. These intermediate exchange (IMEX) processes have been imaged by the CE saturation transfer (CEST) approach with low-power and long-duration irradiation. However, its sensitivity is not optimal, and more importantly, the signal is contaminated by slow magnetization transfer processes. Here, the property of CEST signals is compared to a CE-sensitive spin-locking (CESL) technique irradiating at the labile proton frequency. Firstly, using a higher power and shorter irradiation in CE-MRI yields i) increasing selectivity to faster chemical exchange rates by higher sensitivity to faster exchanges and less sensitivity to slower CE and magnetization transfer processes, and ii) decreasing in vivo asymmetric magnetization transfer contrast measured at ±15 ppm. The sensitivity gain of CESL over CEST is higher for a higher-power and shorter irradiation. Unlike CESL, CEST signals oscillate at a very high power and short irradiation. Secondly, time-dependent CEST and CESL signals are well modeled by analytical solutions of CE-MRI with asymmetric population approximation (CEAPA), which can be used for quantitative CE-MRI, and validated by simulations of Bloch-McConnell equations and phantom experiments. Lastly, in vivo amine-water proton exchange contrast measured at 2.5 ppm with ω1 of 500 Hz is 18% higher in sensitivity for CESL than CEST at 9.4 T. Overall, CESL provides better exchange rate selectivity and sensitivity than CEST; therefore, CESL is more suitable for CE-MRI of IMEX protons. PMID:25199631

  5. Accuracy in the quantification of chemical exchange saturation transfer (CEST) and relayed nuclear Overhauser enhancement (rNOE) saturation transfer effects.

    Science.gov (United States)

    Zhang, Xiao-Yong; Wang, Feng; Li, Hua; Xu, Junzhong; Gochberg, Daniel F; Gore, John C; Zu, Zhongliang

    2017-07-01

    Accurate quantification of chemical exchange saturation transfer (CEST) effects, including dipole-dipole mediated relayed nuclear Overhauser enhancement (rNOE) saturation transfer, is important for applications and studies of molecular concentration and transfer rate (and thereby pH or temperature). Although several quantification methods, such as Lorentzian difference (LD) analysis, multiple-pool Lorentzian fits, and the three-point method, have been extensively used in several preclinical and clinical applications, the accuracy of these methods has not been evaluated. Here we simulated multiple-pool Z spectra containing the pools that contribute to the main CEST and rNOE saturation transfer signals in the brain, numerically fit them using the different methods, and then compared their derived CEST metrics with the known solute concentrations and exchange rates. Our results show that the LD analysis overestimates contributions from amide proton transfer (APT) and intermediate exchanging amine protons; the three-point method significantly underestimates both APT and rNOE saturation transfer at -3.5 ppm (NOE(-3.5)). The multiple-pool Lorentzian fit is more accurate than the other two methods, but only at lower irradiation powers (≤1 μT at 9.4 T) within the range of our simulations. At higher irradiation powers, this method is also inaccurate because of the presence of a fast exchanging CEST signal that has a non-Lorentzian lineshape. Quantitative parameters derived from in vivo images of rodent brain tumor obtained using an irradiation power of 1 μT were also compared. Our results demonstrate that all three quantification methods show similar contrasts between tumor and contralateral normal tissue for both APT and the NOE(-3.5). However, the quantified values of the three methods are significantly different. Our work provides insight into the fitting accuracy obtainable in a complex tissue model and provides guidelines for evaluating other newly developed

  6. CEST and PARACEST MR contrast agents

    International Nuclear Information System (INIS)

    Hancu, Ileana; Dixon, W. Thomas; Woods, Mark; Sherry, A. Dean; Vinogradov, Elena; Lenkinski, Robert E.

    2010-01-01

    In this review we describe the status of development for a new class of magnetic resonance (MR) contrast agents, based on chemical exchange saturation transfer (CEST). The mathematics and physics relevant to the description of the CEST effect in MR are presented in an appendix published in the online version only. We discuss the issues arising when translating in vitro results obtained with CEST agents to using these MR agents in in vivo model studies and in humans. Examples are given on how these agents are imaged in vivo. We summarize the status of development of these CEST agents, and speculate about the next steps that may be taken towards the demonstration of CEST MR imaging in clinical applications

  7. [Chemical Exchange Saturation Transfer Imaging of Creatine Metabolites: a 3.0 T MRI Pilot].

    Science.gov (United States)

    Guo, Ying-kun; Li, Zhen-lin; Rong, Yu; Xia, Chun-chao; Zhang, Li-zhi; Peng, Wan-ling; Liu, Xi; Xu, Hua-yan; Zhang, Ti-jiang; Zuo, Pan-li; Schmitt, Benjamin

    2016-03-01

    To determine the feasibility of using chemical exchange saturation transfer (CEST) imaging to measure creatine (Cr) metabolites with 3.0 T MR. Phantoms containing different concentrations of Cr under various pH conditions were studied with CEST sequence on 3.0 T MR imaging. CEST effect and Z spectra were analyzed. Cr exhibited significant CEST effect (± 1.8 ppm, F = 99.08, P 3.0 T MR imaging, and positive correlation was found between the signal intensity and concentration of Cr (r = 0.963, P 3.0 T MR imaging. Creatine concentrations and pH influence CEST effect.

  8. Flip-angle based ratiometric approach for pulsed CEST-MRI pH imaging

    Science.gov (United States)

    Arena, Francesca; Irrera, Pietro; Consolino, Lorena; Colombo Serra, Sonia; Zaiss, Moritz; Longo, Dario Livio

    2018-02-01

    Several molecules have been exploited for developing MRI pH sensors based on the chemical exchange saturation transfer (CEST) technique. A ratiometric approach, based on the saturation of two exchanging pools at the same saturation power, or by varying the saturation power levels on the same pool, is usually needed to rule out the concentration term from the pH measurement. However, all these methods have been demonstrated by using a continuous wave saturation scheme that limits its translation to clinical scanners. This study shows a new ratiometric CEST-MRI pH-mapping approach based on a pulsed CEST saturation scheme for a radiographic contrast agent (iodixanol) possessing a single chemical exchange site. This approach is based on the ratio of the CEST contrast effects at two different flip angles combinations (180°/360° and 180°/720°), keeping constant the mean irradiation RF power (Bavg power). The proposed ratiometric approach index is concentration independent and it showed good pH sensitivity and accuracy in the physiological range between 6.0 and 7.4.

  9. Functional MRI 2.0. {sup 23}Na and CEST imaging; Funktionelle MRT 2.0. {sup 23}Na- und CEST-Bildgebung

    Energy Technology Data Exchange (ETDEWEB)

    Haneder, S. [Uniklinik Koeln, Institut fuer Diagnostische und Interventionelle Radiologie, Koeln (Germany); Konstandin, S. [Universitaet Bremen, MR-Bildgebung und -Spektroskopie, Fachbereich 1 (Physik/Elektrotechnik), Bremen (Germany); Fraunhofer MEVIS, Institut fuer Bildgestuetzte Medizin, Bremen (Germany)

    2016-02-15

    In recent years the purely morphological magnetic resonance imaging (MRI) has been increasingly flanked by so-called functional imaging methods, such as diffusion-weighted imaging (DWI), to obtain additional information about tissue or pathological processes. This review article presents two MR techniques that can detect physiological processes in the human body. In contrast to all other functional MR imaging techniques, which are based on hydrogen protons, the first technique presented (X-nuclei imaging) uses the spin of other nuclei for imaging and consequently allows a completely different insight into the human body. In this article X-nuclei imaging is focused on sodium ({sup 23}Na) MRI because it currently represents the main focus of research in this field due to the favorable MR properties of sodium. The second MR technique presented is the relatively novel chemical exchange saturation transfer (CEST) imaging that can detect exchange processes between protons in metabolites and protons in free water. The first part of this article introduces the basic technical principles, problems, advantages and disadvantages of these two MR techniques, whereas the second part highlights the potential clinical applications. Examples illustrate several potential applications in neuroimaging (e. g. stroke and tumors), musculoskeletal imaging (e. g. osteoarthritis and degenerative processes) and abdominal imaging (e. g. kidneys and hypertension). Both techniques inherently contain an incredible potential for future imaging but are still on the threshold of clinical use and are currently under evaluation in many university centers. (orig.) [German] In den letzten Jahren wird die reine morphologische Magnetresonanztomographie (MRT) zunehmend von sogenannten funktionellen Bildgebungsmethoden, wie der diffusionsgewichteten Bildgebung (''diffusion-weighted imaging'', DWI), flankiert, um zusaetzliche Informationen ueber Gewebe oder pathologische Prozesse zu

  10. pH imaging of mouse kidneys in vivo using a frequency-dependent paraCEST agent

    Science.gov (United States)

    Wu, Yunkou; Zhang, Shanrong; Soesbe, Todd C.; Yu, Jing; Vinogradov, Elena; Lenkinski, Robert E.; Sherry, A. Dean

    2015-01-01

    Purpose This study explored the feasibility of using a pH responsive paraCEST agent to image the pH gradient in kidneys of healthy mice. Methods CEST signals were acquired on an Agilent 9.4 T small animal MRI system using a steady-state gradient echo pulse sequence after a bolus injection of agent. The magnetic field inhomogeneity across each kidney was corrected using the WASSR method and pH maps were calculated by measuring the frequency of water exchange signal arising from the agent. Results Dynamic CEST studies demonstrated that the agent was readily detectable in kidneys only between 4 to 12 min post-injection. The CEST images showed a higher signal intensity in the pelvis and calyx regions and lower signal intensity in the medulla and cortex regions. The pH maps reflected tissue pH values spanning from 6.0 to 7.5 in kidneys of healthy mice. Conclusion This study demonstrated that pH maps of the kidney can be imaged in vivo by measuring the pH-dependent chemical shift of a single water exchange CEST peak without prior knowledge of the agent concentration in vivo. The results demonstrate the potential of using a simple frequency-dependent paraCEST agent for mapping tissue pH in vivo. PMID:26173637

  11. CEST ANALYSIS: AUTOMATED CHANGE DETECTION FROM VERY-HIGH-RESOLUTION REMOTE SENSING IMAGES

    Directory of Open Access Journals (Sweden)

    M. Ehlers

    2012-08-01

    Full Text Available A fast detection, visualization and assessment of change in areas of crisis or catastrophes are important requirements for coordination and planning of help. Through the availability of new satellites and/or airborne sensors with very high spatial resolutions (e.g., WorldView, GeoEye new remote sensing data are available for a better detection, delineation and visualization of change. For automated change detection, a large number of algorithms has been proposed and developed. From previous studies, however, it is evident that to-date no single algorithm has the potential for being a reliable change detector for all possible scenarios. This paper introduces the Combined Edge Segment Texture (CEST analysis, a decision-tree based cooperative suite of algorithms for automated change detection that is especially designed for the generation of new satellites with very high spatial resolution. The method incorporates frequency based filtering, texture analysis, and image segmentation techniques. For the frequency analysis, different band pass filters can be applied to identify the relevant frequency information for change detection. After transforming the multitemporal images via a fast Fourier transform (FFT and applying the most suitable band pass filter, different methods are available to extract changed structures: differencing and correlation in the frequency domain and correlation and edge detection in the spatial domain. Best results are obtained using edge extraction. For the texture analysis, different 'Haralick' parameters can be calculated (e.g., energy, correlation, contrast, inverse distance moment with 'energy' so far providing the most accurate results. These algorithms are combined with a prior segmentation of the image data as well as with morphological operations for a final binary change result. A rule-based combination (CEST of the change algorithms is applied to calculate the probability of change for a particular location. CEST

  12. Determining the chemical exchange saturation transfer (CEST) behavior of citrate and spermine under in vivo conditions

    Science.gov (United States)

    Basharat, Meer; deSouza, Nandita M.; Parkes, Harold G.

    2015-01-01

    Purpose To estimate the exchange rates of labile 1H in citrate and spermine, metabolites present in prostatic secretions, to predict the size of the citrate and spermine CEST effects in vivo. Methods CEST z‐spectra were acquired at high‐field [11.7 Tesla (T)] from citrate and spermine solutions at physiological pH (6.5) using saturation power 6 μT. CEST was performed at different temperatures to determine exchange regimes (slow, intermediate or fast). For low pH solutions of spermine, exchange rates were estimated from resonance line width, fitting z‐spectra using the Bloch equations incorporating exchange, and using quantifying exchange using saturation time experiments (QUEST). These rates were extrapolated to physiological pH. Results Citrate showed little CEST effect at pH 6.5 and temperature (T) = 310 K (maximum 0.001% mM‐1), indicating fast exchange, whereas spermine showed greater CEST effects (maximum 0.2% mM‐1) indicating intermediate‐to‐fast exchange. Extrapolating data acquired from low pH spermine solutions predicts exchange rates at pH 6.5 and T of 310 K of at least 2 × 104s‐1. Conclusion Citrate and spermine show minimal CEST effects at 11.7T even using high saturation power. These effects would be much less than 2% at clinical field‐strengths due to relatively faster exchange and would be masked by CEST from proteins. Magn Reson Med 76:742–746, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26467055

  13. Quantitative chemical exchange saturation transfer (qCEST) MRI--RF spillover effect-corrected omega plot for simultaneous determination of labile proton fraction ratio and exchange rate.

    Science.gov (United States)

    Sun, Phillip Zhe; Wang, Yu; Dai, ZhuoZhi; Xiao, Gang; Wu, Renhua

    2014-01-01

    Chemical exchange saturation transfer (CEST) MRI is sensitive to dilute proteins and peptides as well as microenvironmental properties. However, the complexity of the CEST MRI effect, which varies with the labile proton content, exchange rate and experimental conditions, underscores the need for developing quantitative CEST (qCEST) analysis. Towards this goal, it has been shown that omega plot is capable of quantifying paramagnetic CEST MRI. However, the use of the omega plot is somewhat limited for diamagnetic CEST (DIACEST) MRI because it is more susceptible to direct radio frequency (RF) saturation (spillover) owing to the relatively small chemical shift. Recently, it has been found that, for dilute DIACEST agents that undergo slow to intermediate chemical exchange, the spillover effect varies little with the labile proton ratio and exchange rate. Therefore, we postulated that the omega plot analysis can be improved if RF spillover effect could be estimated and taken into account. Specifically, simulation showed that both labile proton ratio and exchange rate derived using the spillover effect-corrected omega plot were in good agreement with simulated values. In addition, the modified omega plot was confirmed experimentally, and we showed that the derived labile proton ratio increased linearly with creatine concentration (p plot for quantitative analysis of DIACEST MRI. Copyright © 2014 John Wiley & Sons, Ltd.

  14. Biochemical imaging of cervical intervertebral discs with glycosaminoglycan chemical exchange saturation transfer magnetic resonance imaging: feasibility and initial results

    International Nuclear Information System (INIS)

    Schleich, Christoph; Mueller-Lutz, Anja; Zimmermann, Lisa; Boos, Johannes; Wittsack, Hans-Joerg; Antoch, Gerald; Miese, Falk; Schmitt, Benjamin

    2016-01-01

    To evaluate glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging at 3T in the assessment of the GAG content of cervical IVDs in healthy volunteers. Forty-two cervical intervertebral discs of seven healthy volunteers (four females, three males; mean age: 21.4 ± 1.4 years; range: 19-24 years) were examined at a 3T MRI scanner in this prospective study. The MRI protocol comprised standard morphological, sagittal T2 weighted (T2w) images to assess the magnetic resonance imaging (MRI) based grading system for cervical intervertebral disc degeneration (IVD) and biochemical imaging with gagCEST to calculate a region-of-interest analysis of nucleus pulposus (NP) and annulus fibrosus (AF). GagCEST of cervical IVDs was technically successful at 3T with significant higher gagCEST values in NP compared to AF (1.17 % ± 1.03 % vs. 0.79 % ± 1.75 %; p = 0.005). We found topological differences of gagCEST values of the cervical spine with significant higher gagCEST effects in lower IVDs (r = 1; p = 0). We could demonstrate a significant, negative correlation between gagCEST values and cervical disc degeneration of NP (r = -0.360; p = 0.019). Non-degenerated IVDs had significantly higher gagCEST effects compared to degenerated IVDs in NP (1.76 % ± 0.92 % vs. 0.52 % ± 1.17 %; p < 0.001). Biochemical imaging of cervical IVDs is feasible at 3T. GagCEST analysis demonstrated a topological GAG distribution of the cervical spine. The depletion of GAG in the NP with increasing level of morphological degeneration can be assessed using gagCEST imaging. (orig.)

  15. Quantitative chemical exchange saturation transfer with hyperpolarized nuclei (qHyper-CEST): sensing xenon-host exchange dynamics and binding affinities by NMR.

    Science.gov (United States)

    Kunth, M; Witte, C; Schröder, L

    2014-11-21

    The reversible binding of xenon to host molecules has found numerous applications in nuclear magnetic resonance studies. Quantitative characterization of the Xe exchange dynamics is important to understand and optimize the physico-chemical behavior of such Xe hosts, but is often challenging to achieve at low host concentrations. We have investigated a sensitive quantification technique based on chemical exchange saturation transfer with hyperpolarized nuclei, qHyper-CEST. Using simulated signals we demonstrated that qHyper-CEST yielded accurate and precise results and was robust in the presence of large amounts of noise (10%). This is of particular importance for samples with completely unknown exchange rates. Using these findings we experimentally determined the following exchange parameters for the Xe host cryptophane-A monoacid in dimethyl sulfoxide in one type of experiment: the ratio of bound and free Xe, the Xe exchange rate, the resonance frequencies of free and bound Xe, the Xe host occupancy, and the Xe binding constant. Taken together, qHyper-CEST facilitates sensitive quantification of the Xe exchange dynamics and binding to hydrophobic cavities and has the potential to analyze many different host systems or binding sites. This makes qHyper-CEST an indispensable tool for the efficient design of highly specific biosensors.

  16. Characterization of creatine guanidinium proton exchange by water-exchange (WEX) spectroscopy for absolute-pH CEST imaging in vitro.

    Science.gov (United States)

    Goerke, Steffen; Zaiss, Moritz; Bachert, Peter

    2014-05-01

    Chemical exchange saturation transfer (CEST) enables indirect detection of small metabolites in tissue by MR imaging. To optimize and interpret creatine-CEST imaging we characterized the dependence of the exchange-rate constant k(sw) of creatine guanidinium protons in aqueous creatine solutions as a function of pH and temperature T in vitro. Model solutions in the low pH range (pH = 5-6.4) were measured by means of water-exchange (WEX)-filtered ¹H NMR spectroscopy on a 3 T whole-body MR tomograph. An extension of the Arrhenius equation with effective base-catalyzed Arrhenius parameters yielded a general expression for k(sw) (pH, T). The defining parameters were identified as the effective base-catalyzed rate constant k(b,eff) (298.15 K) = (3.009 ± 0.16) × 10⁹  Hz l/mol and the effective activation energy E(A,b,eff)  = (32.27 ± 7.43) kJ/mol at a buffer concentration of c(buffer)  = (1/15) M. As expected, a strong dependence of k(sw) on temperature was observed. The extrapolation of the exchange-rate constant to in vivo conditions (pH = 7.1, T = 37 °C) led to the value of the exchange-rate constant k(sw)  = 1499 Hz. With the explicit function k(sw) (pH, T) available, absolute-pH CEST imaging could be realized and experimentally verified in vitro. By means of our calibration method it is possible to adjust the guanidinium proton exchange-rate constant k(sw) to any desired value by preparing creatine model solutions with a specific pH and temperature. Copyright © 2014 John Wiley & Sons, Ltd.

  17. Chemical exchange saturation transfer (CEST) properties of albumin-binding and gold nanoparticle-bound Eu (III) chelates

    Science.gov (United States)

    Melendez, Milleo Dalmacio

    CEST agents derived from paramagnetic complexes, commonly referred to as PARACEST agents represent a new class of MRI contrast agents that respond to biological information such as pH, temperature, redox, and metabolite levels. In this work, CEST properties of two novel PARACEST agents were investigated upon binding to human serum albumin (HSA) and conjugation to gold nanoparticles (Au NPs). CEST properties of [EuDOTA(O-Et-Tyr)4] -when bound to HSA was studied to address the effect of proteins on CEST. The interaction of this Eu3+ complex to HSA was investigated by performing fluorescent probe displacement studies and it was found to bind HSA at two different binding pockets, the normal warfarin and dansyl glycine binding sites. The lipophilic pendant arms and the negative charge of this complex contribute to the favorable protein binding. However, the CEST signal was reduced 2-fold upon binding to HSA. The exchangeable protons on HSA provide a large proton pool that can exchange with the bound H 2O, competing for the exchange between bulk and bound water. Au NPs coated with [EuDOTA(CAM)4]3+ were prepared using the Brust method and characterized by measuring the CEST properties. The water residence lifetime for the Au-Eu NP conjugates increased 2-fold compared to the free Eu3+ complex presumably, as a result of the formation of hindered structure between the particle and the Eu3+ complex. Sensitivity enhancement in CEST was achieved by slowing down water exchange and increasing the number of exchangeable groups on the agent using Au-Eu NP conjugates. The CEST properties of small molecule PARACEST agents were shown to vary depending on the platform used in assembling larger adducts.

  18. Investigation of Chemical Exchange at Intermediate Exchange Rates using a Combination of Chemical Exchange Saturation Transfer (CEST) and Spin-Locking methods (CESTrho)

    Science.gov (United States)

    Kogan, Feliks; Singh, Anup; Cai, Keija; Haris, Mohammad; Hariharan, Hari; Reddy, Ravinder

    2011-01-01

    Proton exchange imaging is important as it allows for visualization and quantification of the distribution of specific metabolites with conventional MRI. Current exchange mediated MRI methods suffer from poor contrast as well as confounding factors that influence exchange rates. In this study we developed a new method to measure proton exchange which combines chemical exchange saturation transfer (CEST) and T1ρ magnetization preparation methods (CESTrho). We demonstrated that this new CESTrho sequence can detect proton exchange in the slow to intermediate exchange regimes. It has a linear dependence on proton concentration which allows it to be used to quantitatively measure changes in metabolite concentration. Additionally, the magnetization scheme of this new method can be customized to make it insensitive to changes in exchange rate while retaining its dependency on solute concentration. Finally, we showed the feasibility of using CESTrho in vivo. This sequence is able to detect proton exchange at intermediate exchange rates and is unaffected by the confounding factors that influence proton exchange rates thus making it ideal for the measurement of metabolites with exchangeable protons in this exchange regime. PMID:22009759

  19. Increased CEST specificity for amide and fast-exchanging amine protons using exchange-dependent relaxation rate.

    Science.gov (United States)

    Zhang, Xiao-Yong; Wang, Feng; Xu, Junzhong; Gochberg, Daniel F; Gore, John C; Zu, Zhongliang

    2018-02-01

    Chemical exchange saturation transfer (CEST) imaging of amides at 3.5 ppm and fast-exchanging amines at 3 ppm provides a unique means to enhance the sensitivity of detection of, for example, proteins/peptides and neurotransmitters, respectively, and hence can provide important information on molecular composition. However, despite the high sensitivity relative to conventional magnetic resonance spectroscopy (MRS), in practice, CEST often has relatively poor specificity. For example, CEST signals are typically influenced by several confounding effects, including direct water saturation (DS), semi-solid non-specific magnetization transfer (MT), the influence of water relaxation times (T 1w ) and nearby overlapping CEST signals. Although several editing techniques have been developed to increase the specificity by removing DS, semi-solid MT and T 1w influences, it is still challenging to remove overlapping CEST signals from different exchanging sites. For instance, the amide proton transfer (APT) signal could be contaminated by CEST effects from fast-exchanging amines at 3 ppm and intermediate-exchanging amines at 2 ppm. The current work applies an exchange-dependent relaxation rate (R ex ) to address this problem. Simulations demonstrate that: (1) slowly exchanging amides and fast-exchanging amines have distinct dependences on irradiation powers; and (2) R ex serves as a resonance frequency high-pass filter to selectively reduce CEST signals with resonance frequencies closer to water. These characteristics of R ex provide a means to isolate the APT signal from amines. In addition, previous studies have shown that CEST signals from fast-exchanging amines have no distinct features around their resonance frequencies. However, R ex gives Lorentzian lineshapes centered at their resonance frequencies for fast-exchanging amines and thus can significantly increase the specificity of CEST imaging for amides and fast-exchanging amines. Copyright © 2017 John Wiley & Sons

  20. Chemical exchange saturation transfer MR imaging of Parkinson's disease at 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chunmei; Peng, Shuai; Wang, Rui; Chen, Min [Beijing Hospital, Department of Radiology, Beijing (China); Chen, Haibo; Su, Wen [Beijing Hospital, Department of Neurology, Beijing (China); Zhao, Xuna [Peking University, Center for MRI Research and Beijing City Key Lab for Medical Physics and Engineering, Beijing (China); Zhou, Jinyuan [Johns Hopkins University, Department of Radiology, Baltimore, MD (United States)

    2014-10-15

    To demonstrate the feasibility of using chemical exchange saturation transfer (CEST) imaging to detect Parkinson's disease (PD) in patients at 3 Tesla. Twenty-seven PD patients (17 men and 10 women; age range, 54-77 years) and 22 age-matched normal controls (13 men and 9 women; age range, 55-73 years) were examined on a 3-Tesla MRI system. Magnetization transfer spectra with 31 different frequency offsets (-6 to 6 ppm) were acquired at two transverse slices of the head, including the basal ganglia and midbrain. One-way analysis of variance tests was used to compare the differences in CEST imaging signals between PD patients and normal controls. Total CEST signal between the offsets of 0 and 4 ppm in the substantia nigra was significantly lower in PD patients than in normal controls (P = 0.006), which could be associated with the loss of dopaminergic neurons. Protein-based CEST imaging signals at the offset of 3.5 ppm in the globus pallidus, putamen and caudate were significantly increased in PD patients, compared to normal controls (P < 0.001, P = 0.003, P < 0.001, respectively). CEST imaging signals could potentially serve as imaging biomarkers to aid in the non-invasive molecular diagnosis of PD. (orig.)

  1. Chemical exchange saturation transfer MR imaging of Parkinson's disease at 3 Tesla

    International Nuclear Information System (INIS)

    Li, Chunmei; Peng, Shuai; Wang, Rui; Chen, Min; Chen, Haibo; Su, Wen; Zhao, Xuna; Zhou, Jinyuan

    2014-01-01

    To demonstrate the feasibility of using chemical exchange saturation transfer (CEST) imaging to detect Parkinson's disease (PD) in patients at 3 Tesla. Twenty-seven PD patients (17 men and 10 women; age range, 54-77 years) and 22 age-matched normal controls (13 men and 9 women; age range, 55-73 years) were examined on a 3-Tesla MRI system. Magnetization transfer spectra with 31 different frequency offsets (-6 to 6 ppm) were acquired at two transverse slices of the head, including the basal ganglia and midbrain. One-way analysis of variance tests was used to compare the differences in CEST imaging signals between PD patients and normal controls. Total CEST signal between the offsets of 0 and 4 ppm in the substantia nigra was significantly lower in PD patients than in normal controls (P = 0.006), which could be associated with the loss of dopaminergic neurons. Protein-based CEST imaging signals at the offset of 3.5 ppm in the globus pallidus, putamen and caudate were significantly increased in PD patients, compared to normal controls (P < 0.001, P = 0.003, P < 0.001, respectively). CEST imaging signals could potentially serve as imaging biomarkers to aid in the non-invasive molecular diagnosis of PD. (orig.)

  2. Nuclear overhauser enhancement mediated chemical exchange saturation transfer imaging at 7 Tesla in glioblastoma patients.

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    Daniel Paech

    Full Text Available BACKGROUND AND PURPOSE: Nuclear Overhauser Enhancement (NOE mediated chemical exchange saturation transfer (CEST is a novel magnetic resonance imaging (MRI technique on the basis of saturation transfer between exchanging protons of tissue proteins and bulk water. The purpose of this study was to evaluate and compare the information provided by three dimensional NOE mediated CEST at 7 Tesla (7T and standard MRI in glioblastoma patients. PATIENTS AND METHODS: Twelve patients with newly diagnosed histologically proven glioblastoma were enrolled in this prospective ethics committee-approved study. NOE mediated CEST contrast was acquired with a modified three-dimensional gradient-echo sequence and asymmetry analysis was conducted at 3.3 ppm (B1 = 0.7 µT to calculate the magnetization transfer ratio asymmetry (MTR(asym. Contrast enhanced T1 (CE-T1 and T2-weighted images were acquired at 3T and used for data co-registration and comparison. RESULTS: Mean NOE mediated CEST signal based on MTR(asym values over all patients was significantly increased (p<0.001 in CE-T1 tumor (-1.99 ± 1.22%, tumor necrosis (-1.36 ± 1.30% and peritumoral CEST hyperintensities (PTCH within T2 edema margins (-3.56 ± 1.24% compared to contralateral normal appearing white matter (-8.38 ± 1.19%. In CE-T1 tumor (p = 0.015 and tumor necrosis (p<0.001 mean MTR(asym values were significantly higher than in PTCH. Extent of the surrounding tumor hyperintensity was smaller in eight out of 12 patients on CEST than on T2-weighted images, while four displayed at equal size. In all patients, isolated high intensity regions (0.40 ± 2.21% displayed on CEST within the CE-T1 tumor that were not discernible on CE-T1 or T2-weighted images. CONCLUSION: NOE mediated CEST Imaging at 7 T provides additional information on the structure of peritumoral hyperintensities in glioblastoma and displays isolated high intensity regions within the CE-T1 tumor that cannot be acquired on CE-T1 or T2

  3. APT and CEST Techniques for Clinical MRI

    NARCIS (Netherlands)

    Keupp, J.

    2011-01-01

    Chemical exchange saturation transfer (CEST) based in vivo detectionand quantification of endogenous macro-molecules (i.e., amide proton transfer, APT) or exogenous contrast agents is a highly sensitivemolecular MRI technique bearing a substantial clinical potential forexample in oncology or for

  4. TmDOTA-tetraglycinate encapsulated liposomes as pH-sensitive LipoCEST agents.

    Directory of Open Access Journals (Sweden)

    Ana Christina L Opina

    Full Text Available Lanthanide DOTA-tetraglycinate (LnDOTA-(gly₄⁻ complexes contain four magnetically equivalent amide protons that exchange with protons of bulk water. The rate of this base catalyzed exchange process has been measured using chemical exchange saturation transfer (CEST NMR techniques as a function of solution pH for various paramagnetic LnDOTA-(gly₄⁻ complexes to evaluate the effects of lanthanide ion size on this process. Complexes with Tb(III, Dy(III, Tm(III and Yb(III were chosen because these ions induce large hyperfine shifts in all ligand protons, including the exchanging amide protons. The magnitude of the amide proton CEST exchange signal differed for the four paramagnetic complexes in order, Yb>Tm>Tb>Dy. Although the Dy(III complex showed the largest hyperfine shift as expected, the combination of favorable chemical shift and amide proton CEST linewidth in the Tm(III complex was deemed most favorable for future in vivo applications where tissue magnetization effects can interfere. TmDOTA-(gly₄⁻ at various concentrations was encapsulated in the core interior of liposomes to yield lipoCEST particles for molecular imaging. The resulting nanoparticles showed less than 1% leakage of the agent from the interior over a range of temperatures and pH. The pH versus amide proton CEST curves differed for the free versus encapsulated agents over the acidic pH regions, consistent with a lower proton permeability across the liposomal bilayer for the encapsulated agent. Nevertheless, the resulting lipoCEST nanoparticles amplify the CEST sensitivity by a factor of ∼10⁴ compared to the free, un-encapsulated agent. Such pH sensitive nano-probes could prove useful for pH mapping of liposomes targeted to tumors.

  5. Advantages of paramagnetic chemical exchange saturation transfer (CEST) complexes having slow to intermediate water exchange properties as responsive MRI agents.

    Science.gov (United States)

    Soesbe, Todd C; Wu, Yunkou; Dean Sherry, A

    2013-07-01

    Paramagnetic chemical exchange saturation transfer (PARACEST) complexes are exogenous contrast agents that have great potential to further extend the functional and molecular imaging capabilities of magnetic resonance. As a result of the presence of a central paramagnetic lanthanide ion (Ln(3+) ≠ La(3+) , Gd(3+) , Lu(3+) ) within the chelate, the resonance frequencies of exchangeable protons bound to the PARACEST agent are shifted far away from the bulk water frequency. This large chemical shift, combined with an extreme sensitivity to the chemical exchange rate, make PARACEST agents ideally suited for the reporting of significant biological metrics, such as temperature, pH and the presence of metabolites. In addition, the ability to turn PARACEST agents 'off' and 'on' using a frequency-selective saturation pulse gives them a distinct advantage over Gd(3+) -based contrast agents. A current challenge for PARACEST research is the translation of the promising in vitro results into in vivo systems. This short review article first describes the basic theory behind PARACEST contrast agents, their benefits over other contrast agents and their applications to MRI. It then describes some of the recent PARACEST research results: specifically, pH measurements using water molecule exchange rate modulation, T2 exchange contrast caused by water molecule exchange, the use of ultrashort TEs (TE < 10 µs) to overcome T2 exchange line broadening and the potential application of T2 exchange as a new contrast mechanism for MRI. Copyright © 2012 John Wiley & Sons, Ltd.

  6. Imaging of endogenous exchangeable proton signals in the human brain using frequency labeled exchange transfer imaging.

    Science.gov (United States)

    Yadav, Nirbhay N; Jones, Craig K; Hua, Jun; Xu, Jiadi; van Zijl, Peter C M

    2013-04-01

    To image endogenous exchangeable proton signals in the human brain using a recently reported method called frequency labeled exchange transfer (FLEX) MRI. As opposed to labeling exchangeable protons using saturation (i.e., chemical exchange saturation transfer, or CEST), FLEX labels exchangeable protons with their chemical shift evolution. The use of short high-power frequency pulses allows more efficient labeling of rapidly exchanging protons, while time domain acquisition allows removal of contamination from semi-solid magnetization transfer effects. FLEX-based exchangeable proton signals were detected in human brain over the 1-5 ppm frequency range from water. Conventional magnetization transfer contrast and the bulk water signal did not interfere in the FLEX spectrum. The information content of these signals differed from in vivo CEST data in that the average exchange rate of these signals was 350-400 s(-1) , much faster than the amide signal usually detected using direct saturation (∼30 s(-1) ). Similarly, fast exchanging protons could be detected in egg white in the same frequency range where amide and amine protons of mobile proteins and peptides are known to resonate. FLEX MRI in the human brain preferentially detects more rapidly exchanging amide/amine protons compared to traditional CEST experiments, thereby changing the information content of the exchangeable proton spectrum. This has the potential to open up different types of endogenous applications as well as more easy detection of rapidly exchanging protons in diaCEST agents or fast exchanging units such as water molecules in paracest agents without interference of conventional magnetization transfer contrast. Copyright © 2013 Wiley Periodicals, Inc.

  7. Chemical Exchange Saturation Transfer MR Imaging Is Superior to Diffusion Tensor Imaging in the Diagnosis and Severity Evaluation of Parkinson's Disease: a Study on Substantia Nigra and Striatum

    Directory of Open Access Journals (Sweden)

    Chunmei eLi

    2015-10-01

    Full Text Available Parkinson’s disease (PD is a neurodegenerative disorder characterized by nigrostriatal cell loss. To date the diagnosis of PD is still based primarily on the clinical manifestations which may be typical and obvious only in advanced-stage PD. Thus, it is crucial to find a reliable marker for the diagnosis of PD. We conducted this study to assess the diagnostic efficiency of chemical-exchange-saturation-transfer (CEST imaging and diffusion-tensor imaging (DTI in PD at 3 Tesla by evaluating changes on substantia nigra and striatum. Twenty-three PD patients and twenty-three age-matched normal controls were recruited. All patients and controls were imaged on a 3 Tesla MR system, using an 8-channel head coil. CEST imaging was acquired in two transverse slices of the head, including substantia nigra and striatum. The magnetization-transfer-ratio asymmetry at 3.5 ppm, MTRasym(3.5ppm, and the total CEST signal intensity between 0 and 4 ppm were calculated. Multi-slice DTI was acquired for all the patients and normal controls. Quantitative analysis was performed on the substantia nigra, globus pallidus, putamen and caudate. The MTRasym(3.5ppm value, the total CEST signal intensity and fractional anisotropy (FA value of the substantia nigra were all significantly lower in PD patients than in normal controls (P = 0.003, P = 0.004 and P < 0.001, respectively. The MTRasym(3.5ppm values of the putamen and the caudate were significantly higher in PD patients than in normal controls (P = 0.010 and P = 0.009, respectively. There were no significant differences for the mean diffusivity (MD in these four regions between PD patients and normal controls. In conclusion, CEST MR imaging provided multiple CEST image contrasts in the substantia nigra and the striatum in PD and may be superior to DTI in the diagnosis of PD.

  8. A comparison of exogenous and endogenous CEST MRI methods for evaluating in vivo pH.

    Science.gov (United States)

    Lindeman, Leila R; Randtke, Edward A; High, Rachel A; Jones, Kyle M; Howison, Christine M; Pagel, Mark D

    2018-05-01

    Extracellular pH (pHe) is an important biomarker for cancer cell metabolism. Acido-chemical exchange saturation transfer (CEST) MRI uses the contrast agent iopamidol to create spatial maps of pHe. Measurements of amide proton transfer exchange rates (k ex ) from endogenous CEST MRI were compared to pHe measurements by exogenous acido-CEST MRI to determine whether endogenous k ex could be used as a proxy for pHe measurements. Spatial maps of pHe and k ex were obtained using exogenous acidoCEST MRI and an endogenous CEST MRI analyzed with the omega plot method, respectively, to evaluate mouse kidney, a flank tumor model, and a spontaneous lung tumor model. The pHe and k ex results were evaluated using pixelwise comparisons. The k ex values obtained from endogenous CEST measurements did not correlate with the pHe results from exogenous CEST measurements. The k ex measurements were limited to fewer pixels and had a limited dynamic range relative to pHe measurements. Measurements of k ex with endogenous CEST MRI cannot substitute for pHe measurements with acidoCEST MRI. Whereas endogenous CEST MRI may still have good utility for evaluating some specific pathologies, exogenous acido-CEST MRI is more appropriate when evaluating pathologies based on pHe values. Magn Reson Med 79:2766-2772, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  9. Double agents and secret agents: the emerging fields of exogenous chemical exchange saturation transfer and T2-exchange magnetic resonance imaging contrast agents for molecular imaging.

    Science.gov (United States)

    Daryaei, Iman; Pagel, Mark D

    2015-01-01

    Two relatively new types of exogenous magnetic resonance imaging contrast agents may provide greater impact for molecular imaging by providing greater specificity for detecting molecular imaging biomarkers. Exogenous chemical exchange saturation transfer (CEST) agents rely on the selective saturation of the magnetization of a proton on an agent, followed by chemical exchange of a proton from the agent to water. The selective detection of a biomarker-responsive CEST signal and an unresponsive CEST signal, followed by the ratiometric comparison of these signals, can improve biomarker specificity. We refer to this improvement as a "double-agent" approach to molecular imaging. Exogenous T 2 -exchange agents also rely on chemical exchange of protons between the agent and water, especially with an intermediate rate that lies between the slow exchange rates of CEST agents and the fast exchange rates of traditional T 1 and T 2 agents. Because of this intermediate exchange rate, these agents have been relatively unknown and have acted as "secret agents" in the contrast agent research field. This review exposes these secret agents and describes the merits of double agents through examples of exogenous agents that detect enzyme activity, nucleic acids and gene expression, metabolites, ions, redox state, temperature, and pH. Future directions are also provided for improving both types of contrast agents for improved molecular imaging and clinical translation. Therefore, this review provides an overview of two new types of exogenous contrast agents that are becoming useful tools within the armamentarium of molecular imaging.

  10. ParaCEST Agents Encapsulated in Reverse Nano-Assembled Capsules (RACs): How Slow Molecular Tumbling Can Quench CEST Contrast.

    Science.gov (United States)

    Farashishiko, Annah; Slack, Jacqueline R; Botta, Mauro; Woods, Mark

    2018-01-01

    Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM 3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid (PAA) after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride (PAH) followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. The quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

  11. ParaCEST agents encapsulated in Reverse nano-Assembled Capsules (RACs): How slow molecular tumbling can quench CEST

    Science.gov (United States)

    Farashishiko, Annah; Slack, Jacqueline R.; Botta, Mauro; Woods, Mark

    2018-04-01

    Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the series the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. A significant proportion of the quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

  12. ParaCEST Agents Encapsulated in Reverse Nano-Assembled Capsules (RACs: How Slow Molecular Tumbling Can Quench CEST Contrast

    Directory of Open Access Journals (Sweden)

    Annah Farashishiko

    2018-04-01

    Full Text Available Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid (PAA after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride (PAH followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. The quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

  13. Chemical exchange rotation transfer imaging of intermediate-exchanging amines at 2 ppm.

    Science.gov (United States)

    Zu, Zhongliang; Louie, Elizabeth A; Lin, Eugene C; Jiang, Xiaoyu; Does, Mark D; Gore, John C; Gochberg, Daniel F

    2017-10-01

    Chemical exchange saturation transfer (CEST) imaging of amine protons exchanging at intermediate rates and whose chemical shift is around 2 ppm may provide a means of mapping creatine. However, the quantification of this effect may be compromised by the influence of overlapping CEST signals from fast-exchanging amines and hydroxyls. We aimed to investigate the exchange rate filtering effect of a variation of CEST, named chemical exchange rotation transfer (CERT), as a means of isolating creatine contributions at around 2 ppm from other overlapping signals. Simulations were performed to study the filtering effects of CERT for the selection of transfer effects from protons of specific exchange rates. Control samples containing the main metabolites in brain, bovine serum albumin (BSA) and egg white albumen (EWA) at their physiological concentrations and pH were used to study the ability of CERT to isolate molecules with amines at 2 ppm that exchange at intermediate rates, and corresponding methods were used for in vivo rat brain imaging. Simulations showed that exchange rate filtering can be combined with conventional filtering based on chemical shift. Studies on samples showed that signal contributions from creatine can be separated from those of other metabolites using this combined filter, but contributions from protein amines may still be significant. This exchange filtering can also be used for in vivo imaging. CERT provides more specific quantification of amines at 2 ppm that exchange at intermediate rates compared with conventional CEST imaging. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Exchange rates of creatine kinase metabolites: feasibility of imaging creatine by chemical exchange saturation transfer MRI.

    Science.gov (United States)

    Haris, Mohammad; Nanga, Ravi Prakash Reddy; Singh, Anup; Cai, Kejia; Kogan, Feliks; Hariharan, Hari; Reddy, Ravinder

    2012-11-01

    Creatine (Cr), phosphocreatine (PCr) and adenosine-5-triphosphate (ATP) are major metabolites of the enzyme creatine kinase (CK). The exchange rate of amine protons of CK metabolites at physiological conditions has been limited. In the current study, the exchange rate and logarithmic dissociation constant (pKa) of amine protons of CK metabolites were calculated. Further, the chemical exchange saturation transfer effect (CEST) of amine protons of CK metabolites with bulk water was explored. At physiological temperature and pH, the exchange rate of amine protons in Cr was found to be 7-8 times higher than PCr and ATP. A higher exchange rate in Cr was associated with lower pKa value, suggesting faster dissociation of its amine protons compared to PCr and ATP. CEST MR imaging of these metabolites in vitro in phantoms displayed predominant CEST contrast from Cr and negligible contribution from PCr and ATP with the saturation pulse parameters used in the current study. These results provide a new method to perform high-resolution proton imaging of Cr without contamination from PCr. Potential applications of these finding are discussed. Copyright © 2012 John Wiley & Sons, Ltd.

  15. Relaxation-compensated CEST-MRI at 7 T for mapping of creatine content and pH--preliminary application in human muscle tissue in vivo.

    Science.gov (United States)

    Rerich, Eugenia; Zaiss, Moritz; Korzowski, Andreas; Ladd, Mark E; Bachert, Peter

    2015-11-01

    The small biomolecule creatine is involved in energy metabolism. Mapping of the total creatine (mostly PCr and Cr) in vivo has been done with chemical shift imaging. Chemical exchange saturation transfer (CEST) allows an alternative detection of creatine via water MRI. Living tissue exhibits CEST effects from different small metabolites, including creatine, with four exchanging protons of its guanidinium group resonating about 2 ppm from the water peak and hence contributing to the amine proton CEST peak. The intermediate exchange rate (≈ 1000 Hz) of the guanidinium protons requires high RF saturation amplitude B1. However, strong B1 fields also label semi-solid magnetization transfer (MT) effects originating from immobile protons with broad linewidths (~kHz) in the tissue. Recently, it was shown that endogenous CEST contrasts are strongly affected by the MT background as well as by T1 relaxation of the water protons. We show that this influence can be corrected in the acquired CEST data by an inverse metric that yields the apparent exchange-dependent relaxation (AREX). AREX has some useful linearity features that enable preparation of both concentration, and--by using the AREX-ratio of two RF irradiation amplitudes B1--purely exchange-rate-weighted CEST contrasts. These two methods could be verified in phantom experiments with different concentration and pH values, but also varying water relaxation properties. Finally, results from a preliminary application to in vivo CEST imaging data of the human calf muscle before and after exercise are presented. The creatine concentration increases during exercise as expected and as confirmed by (31)P NMR spectroscopic imaging. However, the estimated concentrations obtained by our method were higher than the literature values: cCr,rest=24.5±3.74mM to cCr,ex=38.32±13.05mM. The CEST-based pH method shows a pH decrease during exercise, whereas a slight increase was observed by (31)P NMR spectroscopy. Copyright © 2015

  16. Investigation of chemical exchange at intermediate exchange rates using a combination of chemical exchange saturation transfer (CEST) and spin-locking methods (CESTrho).

    Science.gov (United States)

    Kogan, Feliks; Singh, Anup; Cai, Keija; Haris, Mohammad; Hariharan, Hari; Reddy, Ravinder

    2012-07-01

    Proton exchange imaging is important as it allows for visualization and quantification of the distribution of specific metabolites with conventional MRI. Current exchange mediated MRI methods suffer from poor contrast as well as confounding factors that influence exchange rates. In this study we developed a new method to measure proton exchange which combines chemical exchange saturation transfer and T(1)(ρ) magnetization preparation methods (CESTrho). We demonstrated that this new CESTrho sequence can detect proton exchange in the slow to intermediate exchange regimes. It has a linear dependence on proton concentration which allows it to be used to quantitatively measure changes in metabolite concentration. Additionally, the magnetization scheme of this new method can be customized to make it insensitive to changes in exchange rate while retaining its dependency on solute concentration. Finally, we showed the feasibility of using CESTrho in vivo. This sequence is able to detect proton exchange at intermediate exchange rates and is unaffected by the confounding factors that influence proton exchange rates thus making it ideal for the measurement of metabolites with exchangeable protons in this exchange regime. Copyright © 2011 Wiley Periodicals, Inc.

  17. Imaging in Vivo Extracellular pH with a Single Paramagnetic Chemical Exchange Saturation Transfer Magnetic Resonance Imaging Contrast Agent

    Directory of Open Access Journals (Sweden)

    Guanshu Liu

    2012-01-01

    Full Text Available The measurement of extracellular pH (pHe has potential utility for cancer diagnoses and for assessing the therapeutic effects of pH-dependent therapies. A single magnetic resonance imaging (MRI contrast agent that is detected through paramagnetic chemical exchange saturation transfer (PARACEST was designed to measure tumor pHe throughout the range of physiologic pH and with magnetic resonance saturation powers that are not harmful to a mouse model of cancer. The chemical characterization and modeling of the contrast agent Yb3+-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid, 10-o-aminoanilide (Yb-DO3A-oAA suggested that the aryl amine of the agent forms an intramolecular hydrogen bond with a proximal carboxylate ligand, which was essential for generating a practical chemical exchange saturation transfer (CEST effect from an amine. A ratio of CEST effects from the aryl amine and amide was linearly correlated with pH throughout the physiologic pH range. The pH calibration was used to produce a parametric pH map of a subcutaneous flank tumor on a mouse model of MCF-7 mammary carcinoma. Although refinements in the in vivo CEST MRI methodology may improve the accuracy of pHe measurements, this study demonstrated that the PARACEST contrast agent can be used to generate parametric pH maps of in vivo tumors with saturation power levels that are not harmful to a mouse model of cancer.

  18. Ex vivo Porcine Model to Measure pH Dependence of gagCEST in the Inter-Vertebral Disc

    Science.gov (United States)

    Melkus, Gerd; Grabau, Michelle; Karampinos, Dimitrios C.; Majumdar, Sharmila

    2013-01-01

    Purpose Studies have linked low pH and loss of glycosaminoglycan (GAG) in the intervertebral discs (IVDs) of patients with discogenic back pain. The purpose of the present study is to determine whether the chemical exchange saturation transfer (CEST) effect of GAG (gagCEST) is pH-dependent and whether it can be used to detect pH changes in IVD specimens. Iopromide, a FDA approved agent for CT/X-Ray, was also evaluated as a pH-sensitive CEST probe to explore the agents’ potential to measure IVD pH. Methods The pH dependency of the CEST effect of chondroitin sulfate (containing GAG) and Iopromide phantoms was investigated at 7 T. Z-spectra from porcine IVD specimens were acquired before and after manipulating the pH with sodium lactate. Iopromide was injected into the specimens and the calibration curve was used to determine the pH status. Results Chondroitin sulfate showed a non-linear dependence of gagCEST effect with pH and gagCEST signal differences were detected in the specimens. The CEST effect of Iopromide resulted in a sigmoidal relation with pH and was used to measure pH. Conclusion gagCEST is sensitive to pH and enables investigation of the IVD pH status. Iopromide CEST is independent of the local GAG concentration and has the potential for measuring pH in the IVD. PMID:23818244

  19. On the transmit field inhomogeneity correction of relaxation‐compensated amide and NOE CEST effects at 7 T

    Science.gov (United States)

    Windschuh, Johannes; Siero, Jeroen C.W.; Zaiss, Moritz; Luijten, Peter R.; Klomp, Dennis W.J.; Hoogduin, Hans

    2017-01-01

    High field MRI is beneficial for chemical exchange saturation transfer (CEST) in terms of high SNR, CNR, and chemical shift dispersion. These advantages may, however, be counter‐balanced by the increased transmit field inhomogeneity normally associated with high field MRI. The relatively high sensitivity of the CEST contrast to B 1 inhomogeneity necessitates the development of correction methods, which is essential for the clinical translation of CEST. In this work, two B 1 correction algorithms for the most studied CEST effects, amide‐CEST and nuclear Overhauser enhancement (NOE), were analyzed. Both methods rely on fitting the multi‐pool Bloch‐McConnell equations to the densely sampled CEST spectra. In the first method, the correction is achieved by using a linear B 1 correction of the calculated amide and NOE CEST effects. The second method uses the Bloch‐McConnell fit parameters and the desired B 1 amplitude to recalculate the CEST spectra, followed by the calculation of B 1‐corrected amide and NOE CEST effects. Both algorithms were systematically studied in Bloch‐McConnell equations and in human data, and compared with the earlier proposed ideal interpolation‐based B 1 correction method. In the low B 1 regime of 0.15–0.50 μT (average power), a simple linear model was sufficient to mitigate B 1 inhomogeneity effects on a par with the interpolation B 1 correction, as demonstrated by a reduced correlation of the CEST contrast with B 1 in both the simulations and the experiments. PMID:28111824

  20. MRI-CEST assessment of tumour perfusion using X-ray iodinated agents: comparison with a conventional Gd-based agent

    Energy Technology Data Exchange (ETDEWEB)

    Anemone, Annasofia; Consolino, Lorena [Universita degli Studi di Torino, Dipartimento di Biotecnologie Molecolari e Scienze per la Salute, Torino (Italy); Longo, Dario Livio [Universita degli Studi di Torino, Istituto di Biostrutture e Bioimmagini (CNR) c/o Centro di Biotecnologie Molecolari, Torino (Italy)

    2017-05-15

    X-ray iodinated contrast media have been shown to generate contrast in MR images when used with the chemical exchange saturation transfer (CEST) approach. The aim of this study is to compare contrast enhancement (CE) capabilities and perfusion estimates between radiographic molecules and a Gd-based contrast agent in two tumour murine models with different vascularization patterns. MRI-CEST and MRI-CE T{sub 1w} images were acquired in murine TS/A and 4 T1 breast tumours upon sequential i.v. injection of iodinated contrast media (iodixanol, iohexol, and iopamidol) and of gadoteridol. The signal enhancements observed in the two acquisition modalities were evaluated using Pearson's correlation, and the correspondence in the spatial distribution was assessed by a voxelwise comparison. A significant, positive correlation was observed between iodinated contrast media and gadoteridol for tumour contrast enhancement and perfusion values for both tumour models (r = 0.51-0.62). High spatial correlations were observed in perfusion maps between iodinated molecules and gadoteridol (r = 0.68-0.86). Tumour parametric maps derived by iodinated contrast media and gadoteridol showed high spatial similarities. A good to strong spatial correlation between tumour perfusion parameters derived from MRI-CEST and MRI-CE modalities indicates that the two procedures provide similar information. (orig.)

  1. Hybrid MR-PET of brain tumours using amino acid PET and chemical exchange saturation transfer MRI.

    Science.gov (United States)

    da Silva, N A; Lohmann, P; Fairney, J; Magill, A W; Oros Peusquens, A-M; Choi, C-H; Stirnberg, R; Stoffels, G; Galldiks, N; Golay, X; Langen, K-J; Jon Shah, N

    2018-06-01

    PET using radiolabelled amino acids has become a promising tool in the diagnostics of gliomas and brain metastasis. Current research is focused on the evaluation of amide proton transfer (APT) chemical exchange saturation transfer (CEST) MR imaging for brain tumour imaging. In this hybrid MR-PET study, brain tumours were compared using 3D data derived from APT-CEST MRI and amino acid PET using O-(2- 18 F-fluoroethyl)-L-tyrosine ( 18 F-FET). Eight patients with gliomas were investigated simultaneously with 18 F-FET PET and APT-CEST MRI using a 3-T MR-BrainPET scanner. CEST imaging was based on a steady-state approach using a B 1 average power of 1μT. B 0 field inhomogeneities were corrected a Prametric images of magnetisation transfer ratio asymmetry (MTR asym ) and differences to the extrapolated semi-solid magnetisation transfer reference method, APT# and nuclear Overhauser effect (NOE#), were calculated. Statistical analysis of the tumour-to-brain ratio of the CEST data was performed against PET data using the non-parametric Wilcoxon test. A tumour-to-brain ratio derived from APT# and 18 F-FET presented no significant differences, and no correlation was found between APT# and 18 F-FET PET data. The distance between local hot spot APT# and 18 F-FET were different (average 20 ± 13 mm, range 4-45 mm). For the first time, CEST images were compared with 18 F-FET in a simultaneous MR-PET measurement. Imaging findings derived from 18 F-FET PET and APT CEST MRI seem to provide different biological information. The validation of these imaging findings by histological confirmation is necessary, ideally using stereotactic biopsy.

  2. Remote transfer of PET images by internet

    International Nuclear Information System (INIS)

    Zuo Chuantao; Lin Xiangtong; Guan Yihui; Zhao Jun

    2003-01-01

    The methodology of PET image remote transfer by Internet has been explored. The original images were got with ECAT EXACT HR + PET, and then converted to Dicom format by Mview software. The Dicom images were transferred via Internet. Thus the PET images were transferred via Internet successfully. The ideal images were obtained away from 8 km. The transfer time of brain and whole body image was (37±3)s and (245±10)s respectively, while the transfer rate was (34.7±2.8) kbyte/s and (34.4±1.5)kbyte/s, respectively. The results showed that the remote transfer via Internet was feasible and practical

  3. Transfer function analysis of radiographic imaging systems

    International Nuclear Information System (INIS)

    Metz, C.E.; Doi, K.

    1979-01-01

    The theoretical and experimental aspects of the techniques of transfer function analysis used in radiographic imaging systems are reviewed. The mathematical principles of transfer function analysis are developed for linear, shift-invariant imaging systems, for the relation between object and image and for the image due to a sinusoidal plane wave object. The other basic mathematical principle discussed is 'Fourier analysis' and its application to an input function. Other aspects of transfer function analysis included are alternative expressions for the 'optical transfer function' of imaging systems and expressions are derived for both serial and parallel transfer image sub-systems. The applications of transfer function analysis to radiographic imaging systems are discussed in relation to the linearisation of the radiographic imaging system, the object, the geometrical unsharpness, the screen-film system unsharpness, other unsharpness effects and finally noise analysis. It is concluded that extensive theoretical, computer simulation and experimental studies have demonstrated that the techniques of transfer function analysis provide an accurate and reliable means for predicting and understanding the effects of various radiographic imaging system components in most practical diagnostic medical imaging situations. (U.K.)

  4. Time-resolved monitoring of enzyme activity with ultrafast Hyper-CEST spectroscopy.

    Science.gov (United States)

    Döpfert, Jörg; Schnurr, Matthias; Kunth, Martin; Rose, Honor May; Hennig, Andreas; Schröder, Leif

    2017-12-23

    We propose a method to dynamically monitor the progress of an enzymatic reaction using NMR of hyperpolarized 129 Xe in a host-guest system. It is based on a displacement assay originally designed for fluorescence experiments that exploits the competitive binding of the enzymatic product on the one hand and a reporter dye on the other hand to a supramolecular host. Recently, this assay has been successfully transferred to NMR, using xenon as a reporter, cucurbit[6]uril as supramolecular host, and chemical exchange saturation transfer with hyperpolarized Xe (Hyper-CEST) as detection technique. Its advantage is that the enzyme acts on the unmodified substrate and that only the product is detected through immediate inclusion into the host. We here apply a method that drastically accelerates the acquisition of Hyper-CEST spectra in vitro using magnetic field gradients. This allows monitoring the dynamic progress of the conversion of lysine to cadaverine with a temporal resolution of ~30 s. Moreover, the method only requires to sample the very early onset of the reaction (Hyper-CEST results correlate with xenon T 2 measurements performed during the enzymatic reaction. This suggests that ultrafast Hyper-CEST spectroscopy can be used for dynamically monitoring enzymatic activity with NMR. Copyright © 2017 John Wiley & Sons, Ltd.

  5. Discriminative Transfer Learning for General Image Restoration

    KAUST Repository

    Xiao, Lei

    2018-04-30

    Recently, several discriminative learning approaches have been proposed for effective image restoration, achieving convincing trade-off between image quality and computational efficiency. However, these methods require separate training for each restoration task (e.g., denoising, deblurring, demosaicing) and problem condition (e.g., noise level of input images). This makes it time-consuming and difficult to encompass all tasks and conditions during training. In this paper, we propose a discriminative transfer learning method that incorporates formal proximal optimization and discriminative learning for general image restoration. The method requires a single-pass discriminative training and allows for reuse across various problems and conditions while achieving an efficiency comparable to previous discriminative approaches. Furthermore, after being trained, our model can be easily transferred to new likelihood terms to solve untrained tasks, or be combined with existing priors to further improve image restoration quality.

  6. Discriminative Transfer Learning for General Image Restoration

    KAUST Repository

    Xiao, Lei; Heide, Felix; Heidrich, Wolfgang; Schö lkopf, Bernhard; Hirsch, Michael

    2018-01-01

    Recently, several discriminative learning approaches have been proposed for effective image restoration, achieving convincing trade-off between image quality and computational efficiency. However, these methods require separate training for each restoration task (e.g., denoising, deblurring, demosaicing) and problem condition (e.g., noise level of input images). This makes it time-consuming and difficult to encompass all tasks and conditions during training. In this paper, we propose a discriminative transfer learning method that incorporates formal proximal optimization and discriminative learning for general image restoration. The method requires a single-pass discriminative training and allows for reuse across various problems and conditions while achieving an efficiency comparable to previous discriminative approaches. Furthermore, after being trained, our model can be easily transferred to new likelihood terms to solve untrained tasks, or be combined with existing priors to further improve image restoration quality.

  7. Comparison of pulsed three-dimensional CEST acquisition schemes at 7 tesla : steady state versus pseudosteady state

    NARCIS (Netherlands)

    Khlebnikov, Vitaly; Geades, Nicolas; Klomp, DWJ; Hoogduin, Hans; Gowland, Penny; Mougin, Olivier

    PURPOSE: To compare two pulsed, volumetric chemical exchange saturation transfer (CEST) acquisition schemes: steady state (SS) and pseudosteady state (PS) for the same brain coverage, spatial/spectral resolution and scan time. METHODS: Both schemes were optimized for maximum sensitivity to amide

  8. Transfer learning improves supervised image segmentation across imaging protocols

    DEFF Research Database (Denmark)

    van Opbroek, Annegreet; Ikram, M. Arfan; Vernooij, Meike W.

    2015-01-01

    with slightly different characteristics. The performance of the four transfer classifiers was compared to that of standard supervised classification on two MRI brain-segmentation tasks with multi-site data: white matter, gray matter, and CSF segmentation; and white-matter- /MS-lesion segmentation......The variation between images obtained with different scanners or different imaging protocols presents a major challenge in automatic segmentation of biomedical images. This variation especially hampers the application of otherwise successful supervised-learning techniques which, in order to perform...... well, often require a large amount of labeled training data that is exactly representative of the target data. We therefore propose to use transfer learning for image segmentation. Transfer-learning techniques can cope with differences in distributions between training and target data, and therefore...

  9. Transfer learning improves supervised image segmentation across imaging protocols.

    Science.gov (United States)

    van Opbroek, Annegreet; Ikram, M Arfan; Vernooij, Meike W; de Bruijne, Marleen

    2015-05-01

    The variation between images obtained with different scanners or different imaging protocols presents a major challenge in automatic segmentation of biomedical images. This variation especially hampers the application of otherwise successful supervised-learning techniques which, in order to perform well, often require a large amount of labeled training data that is exactly representative of the target data. We therefore propose to use transfer learning for image segmentation. Transfer-learning techniques can cope with differences in distributions between training and target data, and therefore may improve performance over supervised learning for segmentation across scanners and scan protocols. We present four transfer classifiers that can train a classification scheme with only a small amount of representative training data, in addition to a larger amount of other training data with slightly different characteristics. The performance of the four transfer classifiers was compared to that of standard supervised classification on two magnetic resonance imaging brain-segmentation tasks with multi-site data: white matter, gray matter, and cerebrospinal fluid segmentation; and white-matter-/MS-lesion segmentation. The experiments showed that when there is only a small amount of representative training data available, transfer learning can greatly outperform common supervised-learning approaches, minimizing classification errors by up to 60%.

  10. Kohvik-restoran C'est La Vie = Cafe-restaurant C'est La Vie

    Index Scriptorium Estoniae

    2008-01-01

    Kohvik-restorani C'est La Vie (Suur-Karja 5, Tallinn) sisekujundusest. Sisearhitekt: Maile Grünberg, kes kavandas ka valdavalt mööbli. Laevalgusti disainis Tõnis Vellama. Skulptuuride (koopiad) autor on keraamik Ülle Rajasalu. Maile Grünbergist, tema viimased tööd. Keldrikorruse ja I korruse plaan, 8 värv. vaadet, foto M. Grünbergist

  11. QUESP and QUEST revisited - fast and accurate quantitative CEST experiments.

    Science.gov (United States)

    Zaiss, Moritz; Angelovski, Goran; Demetriou, Eleni; McMahon, Michael T; Golay, Xavier; Scheffler, Klaus

    2018-03-01

    Chemical exchange saturation transfer (CEST) NMR or MRI experiments allow detection of low concentrated molecules with enhanced sensitivity via their proton exchange with the abundant water pool. Be it endogenous metabolites or exogenous contrast agents, an exact quantification of the actual exchange rate is required to design optimal pulse sequences and/or specific sensitive agents. Refined analytical expressions allow deeper insight and improvement of accuracy for common quantification techniques. The accuracy of standard quantification methodologies, such as quantification of exchange rate using varying saturation power or varying saturation time, is improved especially for the case of nonequilibrium initial conditions and weak labeling conditions, meaning the saturation amplitude is smaller than the exchange rate (γB 1  exchange rate using varying saturation power/time' (QUESP/QUEST) equations allow for more accurate exchange rate determination, and provide clear insights on the general principles to execute the experiments and to perform numerical evaluation. The proposed methodology was evaluated on the large-shift regime of paramagnetic chemical-exchange-saturation-transfer agents using simulated data and data of the paramagnetic Eu(III) complex of DOTA-tetraglycineamide. The refined formulas yield improved exchange rate estimation. General convergence intervals of the methods that would apply for smaller shift agents are also discussed. Magn Reson Med 79:1708-1721, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  12. Resonance Energy Transfer Molecular Imaging Application in Biomedicine

    Directory of Open Access Journals (Sweden)

    NIE Da-hong1,2;TANG Gang-hua1,3

    2016-11-01

    Full Text Available Resonance energy transfer molecular imaging (RETI can markedly improve signal intensity and tissue penetrating capacity of optical imaging, and have huge potential application in the deep-tissue optical imaging in vivo. Resonance energy transfer (RET is an energy transition from the donor to an acceptor that is in close proximity, including non-radiative resonance energy transfer and radiative resonance energy transfer. RETI is an optical imaging technology that is based on RET. RETI mainly contains fluorescence resonance energy transfer imaging (FRETI, bioluminescence resonance energy transfer imaging (BRETI, chemiluminescence resonance energy transfer imaging (CRETI, and radiative resonance energy transfer imaging (RRETI. RETI is the hot field of molecular imaging research and has been widely used in the fields of biology and medicine. This review mainly focuses on RETI principle and application in biomedicine.

  13. Image quality transfer and applications in diffusion MRI

    DEFF Research Database (Denmark)

    Alexander, Daniel C.; Zikic, Darko; Ghosh, Aurobrata

    2017-01-01

    This paper introduces a new computational imaging technique called image quality transfer (IQT). IQT uses machine learning to transfer the rich information available from one-off experimental medical imaging devices to the abundant but lower-quality data from routine acquisitions. The procedure u...

  14. Characterizing Slow Chemical Exchange in Nucleic Acids by Carbon CEST and Low Spin-Lock Field R1ρ NMR Spectroscopy

    Science.gov (United States)

    Zhao, Bo; Hansen, Alexandar L.; Zhang, Qi

    2016-01-01

    Quantitative characterization of dynamic exchange between various conformational states provides essential insights into the molecular basis of many regulatory RNA functions. Here, we present an application of nucleic-acid-optimized carbon chemical exchange saturation transfer (CEST) and low spin-lock field R1ρ relaxation dispersion (RD) NMR experiments in characterizing slow chemical exchange in nucleic acids that is otherwise difficult if not impossible to be quantified by the ZZ-exchange NMR experiment. We demonstrated the application on a 47-nucleotide fluoride riboswitch in the ligand-free state, for which CEST and R1ρ RD profiles of base and sugar carbons revealed slow exchange dynamics involving a sparsely populated (p ~ 10%) and shortly lived (τ ~ 10 ms) NMR “invisible” state. The utility of CEST and low spin-lock field R1ρ RD experiments in studying slow exchange was further validated in characterizing an exchange as slow as ~60 s−1. PMID:24299272

  15. Characterizing slow chemical exchange in nucleic acids by carbon CEST and low spin-lock field R(1ρ) NMR spectroscopy.

    Science.gov (United States)

    Zhao, Bo; Hansen, Alexandar L; Zhang, Qi

    2014-01-08

    Quantitative characterization of dynamic exchange between various conformational states provides essential insights into the molecular basis of many regulatory RNA functions. Here, we present an application of nucleic-acid-optimized carbon chemical exchange saturation transfer (CEST) and low spin-lock field R(1ρ) relaxation dispersion (RD) NMR experiments in characterizing slow chemical exchange in nucleic acids that is otherwise difficult if not impossible to be quantified by the ZZ-exchange NMR experiment. We demonstrated the application on a 47-nucleotide fluoride riboswitch in the ligand-free state, for which CEST and R(1ρ) RD profiles of base and sugar carbons revealed slow exchange dynamics involving a sparsely populated (p ~ 10%) and shortly lived (τ ~ 10 ms) NMR "invisible" state. The utility of CEST and low spin-lock field R(1ρ) RD experiments in studying slow exchange was further validated in characterizing an exchange as slow as ~60 s(-1).

  16. Amide Proton Transfer (APT) MR imaging and Magnetization Transfer (MT) MR imaging of pediatric brain development

    International Nuclear Information System (INIS)

    Zhang, Hong; Kang, Huiying; Peng, Yun; Zhao, Xuna; Jiang, Shanshan; Zhang, Yi; Zhou, Jinyuan

    2016-01-01

    To quantify the brain maturation process during childhood using combined amide proton transfer (APT) and conventional magnetization transfer (MT) imaging at 3 Tesla. Eighty-two neurodevelopmentally normal children (44 males and 38 females; age range, 2-190 months) were imaged using an APT/MT imaging protocol with multiple saturation frequency offsets. The APT-weighted (APTW) and MT ratio (MTR) signals were quantitatively analyzed in multiple brain areas. Age-related changes in MTR and APTW were evaluated with a non-linear regression analysis. The APTW signals followed a decreasing exponential curve with age in all brain regions measured (R"2 = 0.7-0.8 for the corpus callosum, frontal and occipital white matter, and centrum semiovale). The most significant changes appeared within the first year. At maturation, larger decreases in APTW and lower APTW values were found in the white matter. On the contrary, the MTR signals followed an increasing exponential curve with age in the same brain regions measured, with the most significant changes appearing within the initial 2 years. There was an inverse correlation between the MTR and APTW signal intensities during brain maturation. Together with MT imaging, protein-based APT imaging can provide additional information in assessing brain myelination in the paediatric population. (orig.)

  17. Amide Proton Transfer (APT) MR imaging and Magnetization Transfer (MT) MR imaging of pediatric brain development

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hong; Kang, Huiying; Peng, Yun [Beijing Children' s Hospital, Capital Medical University, Imaging Center, Department of Radiology, Beijing (China); Zhao, Xuna [Philips Healthcare, Beijing (China); Jiang, Shanshan; Zhang, Yi; Zhou, Jinyuan [Johns Hopkins University, Division of MR Research, Department of Radiology, Baltimore, MD (United States)

    2016-10-15

    To quantify the brain maturation process during childhood using combined amide proton transfer (APT) and conventional magnetization transfer (MT) imaging at 3 Tesla. Eighty-two neurodevelopmentally normal children (44 males and 38 females; age range, 2-190 months) were imaged using an APT/MT imaging protocol with multiple saturation frequency offsets. The APT-weighted (APTW) and MT ratio (MTR) signals were quantitatively analyzed in multiple brain areas. Age-related changes in MTR and APTW were evaluated with a non-linear regression analysis. The APTW signals followed a decreasing exponential curve with age in all brain regions measured (R{sup 2} = 0.7-0.8 for the corpus callosum, frontal and occipital white matter, and centrum semiovale). The most significant changes appeared within the first year. At maturation, larger decreases in APTW and lower APTW values were found in the white matter. On the contrary, the MTR signals followed an increasing exponential curve with age in the same brain regions measured, with the most significant changes appearing within the initial 2 years. There was an inverse correlation between the MTR and APTW signal intensities during brain maturation. Together with MT imaging, protein-based APT imaging can provide additional information in assessing brain myelination in the paediatric population. (orig.)

  18. PRO-QUEST: a rapid assessment method based on progressive saturation for quantifying exchange rates using saturation times in CEST.

    Science.gov (United States)

    Demetriou, Eleni; Tachrount, Mohamed; Zaiss, Moritz; Shmueli, Karin; Golay, Xavier

    2018-03-05

    To develop a new MRI technique to rapidly measure exchange rates in CEST MRI. A novel pulse sequence for measuring chemical exchange rates through a progressive saturation recovery process, called PRO-QUEST (progressive saturation for quantifying exchange rates using saturation times), has been developed. Using this method, the water magnetization is sampled under non-steady-state conditions, and off-resonance saturation is interleaved with the acquisition of images obtained through a Look-Locker type of acquisition. A complete theoretical framework has been set up, and simple equations to obtain the exchange rates have been derived. A reduction of scan time from 58 to 16 minutes has been obtained using PRO-QUEST versus the standard QUEST. Maps of both T 1 of water and B 1 can simply be obtained by repetition of the sequence without off-resonance saturation pulses. Simulations and calculated exchange rates from experimental data using amino acids such as glutamate, glutamine, taurine, and alanine were compared and found to be in good agreement. The PRO-QUEST sequence was also applied on healthy and infarcted rats after 24 hours, and revealed that imaging specificity to ischemic acidification during stroke was substantially increased relative to standard amide proton transfer-weighted imaging. Because of the reduced scan time and insensitivity to nonchemical exchange factors such as direct water saturation, PRO-QUEST can serve as an excellent alternative for researchers and clinicians interested to map pH changes in vivo. © 2018 International Society for Magnetic Resonance in Medicine.

  19. Evaluating the influence of initial magnetization conditions on extracted exchange parameters in NMR relaxation experiments: applications to CPMG and CEST

    Energy Technology Data Exchange (ETDEWEB)

    Yuwen, Tairan; Sekhar, Ashok; Kay, Lewis E., E-mail: kay@pound.med.utoronto.ca [The University of Toronto, Departments of Molecular Genetics, Biochemistry and Chemistry (Canada)

    2016-08-15

    Transient excursions of native protein states to functionally relevant higher energy conformations often occur on the μs–ms timescale. NMR spectroscopy has emerged as an important tool to probe such processes using techniques such as Carr–Purcell–Meiboom–Gill (CPMG) relaxation dispersion and Chemical Exchange Saturation Transfer (CEST). The extraction of kinetic and structural parameters from these measurements is predicated upon mathematical modeling of the resulting relaxation profiles, which in turn relies on knowledge of the initial magnetization conditions at the start of the CPMG/CEST relaxation elements in these experiments. Most fitting programs simply assume initial magnetization conditions that are given by equilibrium populations, which may be incorrect in certain implementations of experiments. In this study we have quantified the systematic errors in extracted parameters that are generated from analyses of CPMG and CEST experiments using incorrect initial boundary conditions. We find that the errors in exchange rates (k{sub ex}) and populations (p{sub E}) are typically small (<10 %) and thus can be safely ignored in most cases. However, errors become larger and cannot be fully neglected (20–40 %) as k{sub ex} falls near the lower limit of each method or when short CPMG/CEST relaxation elements are used in these experiments. The source of the errors can be rationalized and their magnitude given by a simple functional form. Despite the fact that errors tend to be small, it is recommended that the correct boundary conditions be implemented in fitting programs so as to obtain as robust estimates of exchange parameters as possible.

  20. Spectrally Undiscerned Isomers Might Lead to Erroneous Determination of Water Exchange Rates of paraCEST Eu(III) Agents.

    Science.gov (United States)

    Cakić, Nevenka; Tickner, Ben; Zaiss, Moritz; Esteban-Gómez, David; Platas-Iglesias, Carlos; Angelovski, Goran

    2017-07-17

    We report a detailed study of the solution structure and water exchange rate of a Eu(III) complex with the cyclen-based ligand L 1 , containing (S)-2-(2-acetamido)-3-(4-(trifluoromethyl)phenyl)propanoate pendant arms at positions 1 and 7 of the cyclen ring and acetylglycinate pendants at positions 4 and 10. The EuL 1 complex was characterized by a combination of NMR and luminescence spectroscopy and density functional theory (DFT) calculations. The chemical exchange saturation transfer (CEST) spectra obtained at different temperatures and saturation powers present a CEST signal attributed to the coordinated water molecule. However, the spectra recorded at low temperatures (10 °C) and low saturation powers revealed the presence of two different species with coordinated water molecules having very similar chemical shifts. Determination of the water exchange rates of the coordinated water molecules was carried out by using the Bloch four-pool model that accounts for the presence of these isomers, and this model was compared to conventional methods for CEST quantification, namely the Omega plot and QUESP (quantification of exchange rate as a function of saturation power), which assume the presence of a single CEST active species. The results indicated that only the four-pool Bloch equations provide reasonable water exchange rates and activation parameters. Solution NMR studies and DFT calculations indicated that the two isomers present in solution correspond to the SS-Δ(λλλλ) and SS-Λ(δδδδ) isomers, which present capped square-antiprismatic (SAP) coordination environments. Additional NMR studies on the EuL 2 and EuL 3 complexes, which present four (S)-2-(2-acetamido)-3-(4-(trifluoromethyl)phenyl)propanoate or acetylglycinate pendant arms, respectively, confirm the results obtained for EuL 1 .

  1. Magnetic resonance imaging findings after rectus femoris transfer surgery

    International Nuclear Information System (INIS)

    Gold, Garry E.; Asakawa, Deanna S.; Blemker, Silvia S.; Delp, Scott L.

    2004-01-01

    We describe the magnetic resonance (MR) imaging appearance of the knee flexor and extensor tendons after bilateral rectus femoris transfer and hamstring lengthening surgery in five patients (10 limbs) with cerebral palsy. Three-dimensional models of the path of the transferred tendon were constructed in all cases. MR images of the transferred and lengthened tendons were examined and compared with images from ten non-surgical subjects. The models showed that the path of the transferred rectus femoris tendon had a marked angular deviation near the transfer site in all cases. MR imaging demonstrated irregular areas of low signal intensity near the transferred rectus femoris and around the hamstrings in all subjects. Eight of the ten post-surgical limbs showed evidence of fluid near or around the transferred or lengthened tendons. This was not observed in the non-surgical subjects. Thus, MR imaging of patients with cerebral palsy after rectus femoris transfer and hamstring-lengthening surgery shows evidence of signal intensity and contour changes, even several years after surgery. (orig.)

  2. Real-time transfer and display of radiography image

    International Nuclear Information System (INIS)

    Liu Ximing; Wu Zhifang; Miao Jicheng

    2000-01-01

    The information process network of cobalt-60 container inspection system is a local area network based on PC. The system requires reliable transfer of radiography image between collection station and process station and the real-time display of radiography image on process station. Due to the very high data acquisition rate, in order to realize the real-time transfer and display of radiography image, 100 M Ethernet technology and network process communication technology are adopted in the system. Windows Sockets is the most common process communication technology up to now. Several kinds of process communication way under Windows Sockets technology are compared and tested. Finally the author realized 1 Mbyte/s' inerrant image transfer and real-time display with blocked datagram transfer technology

  3. Conjugate Image Theory Applied on Capacitive Wireless Power Transfer

    OpenAIRE

    Ben Minnaert; Nobby Stevens

    2017-01-01

    Wireless power transfer using a magnetic field through inductive coupling is steadily entering the market in a broad range of applications. However, for certain applications, capacitive wireless power transfer using electric coupling might be preferable. In order to obtain a maximum power transfer efficiency, an optimal compensation network must be designed at the input and output ports of the capacitive wireless link. In this work, the conjugate image theory is applied to determine this opti...

  4. Characterisation of a CMOS charge transfer device for TDI imaging

    International Nuclear Information System (INIS)

    Rushton, J.; Holland, A.; Stefanov, K.; Mayer, F.

    2015-01-01

    The performance of a prototype true charge transfer imaging sensor in CMOS is investigated. The finished device is destined for use in TDI applications, especially Earth-observation, and to this end radiation tolerance must be investigated. Before this, complete characterisation is required. This work starts by looking at charge transfer inefficiency and then investigates responsivity using mean-variance techniques

  5. Assessment of the patellofemoral cartilage: Correlation of knee pain score with magnetic resonance cartilage grading and magnetization transfer ratio asymmetry of glycosaminoglycan chemical exchange saturation transfer.

    Science.gov (United States)

    Lee, Young Han; Yang, Jaemoon; Jeong, Ha-Kyu; Suh, Jin-Suck

    2017-01-01

    Biochemical imaging of glycosaminoglycan chemical exchange saturation transfer (gagCEST) could predict the depletion of glycosaminoglycans (GAG) in early osteoarthritis. The purpose of this study was to evaluate the relationship between the magnetization transfer ratio asymmetry (MTR asym ) of gagCEST images and visual analog scale (VAS) pain scores in the knee joint. This retrospective study was approved by the institutional review board. A phantom study was performed using hyaluronic acid to validate the MTR asym values of gagCEST images. Knee magnetic resonance (MR) images of 22 patients (male, 9; female, 13; mean age, 50.3years; age range; 25-79years) with knee pain were included in this study. The MR imaging (MRI) protocol involved standard knee MRI as well as gagCEST imaging, which allowed region-of-interest analyses of the patellar facet and femoral trochlea. The MTR asym at 1.0ppm was calculated at each region. The cartilages of the patellar facets and femoral trochlea were graded according to the Outerbridge classification system. Data regarding the VAS scores of knee pain were collected from the electronic medical records of the patients. Statistical analysis was performed using Spearman's correlation. The results of the phantom study revealed excellent correlation between the MTR asym values and the concentration of GAGs (r=0.961; p=0.003). The cartilage grades on the MR images showed significant negative correlation with the MTR asym values in the patellar facet and femoral trochlea (r=-0.460; p=0.031 and r=-0.543; p=0.009, respectively). The VAS pain scores showed significant negative correlation with the MTR asym values in the patellar facet and femoral trochlea (r=-0.435; p=0.043 and r=-0.671; p=0.001, respectively). The pain scores were associated with the morphological and biochemical changes in articular cartilages visualized on knee MR images. The biochemical changes, visualized in terms of the MTR asym values of the gagCEST images, exhibited

  6. Magnetization transfer MR of cerebrovascular disorders using calculated images

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, Kyoko; Watabe, Tsuneya; Amanuma, Makoto; Heshiki, Atsuko [Saitama Medical School, Moroyama, Saitama (Japan)

    1997-06-01

    This study applied a magnetization transfer contrast method to patients with cerebrovascular disorders. A 1.5 T superconducting MR unit was used, and magnetization transfer ratio (MTR) images were calculated by evaluating two paired images before and after off-resonance gradient echo pulse sequences. The normal white matter showed the highest MTRs, CSF the lowest, and gray matter, intermediate. Cerebral ischemic patients showed two patterns according to the chronological stage of the affected area. Lesions in the acute and subacute stages revealed higher transfer rates than those in the chronic stage. Patients with cerebral hemorrhage were divided into three groups: the hyperacute group showed a low transfer pattern; the acute group presented inhomogeneous high transfer rates; and the subacute group showed remarkably low transfer rates. In the acute and subacute ischemic stages, increased macromolecules caused higher MTRs than in the chronic stage. In hemorrhagic groups, low MTRs in subacute hemorrhage reflected the transfer of methemoglobin. High MTRs in acute hemorrhage with rich deoxyhemoglobin suggested increased fibrin, plasma, and serum components of macromolecules. The MTC method provided new chronological information on cerebral hemorrhage, adding to that provided by routine MR images. (author)

  7. Past, present, and future of sublimation transfer imaging

    Science.gov (United States)

    Akada, Masanori

    1990-07-01

    SONY's announcement of tlavica system shaked the world in 1981. In the new nonphotographic imaging system, image is acquired with CCD to be converted into electric image-signal, stored in magnetic recording media,displayed on a CR1 and printed on a special sheet. To get a hard copy, Sublimation Transfer technology was developed. That announcement brought about world-wide R&D of competitive color imaging systems: Ink-jet, Wax transfer,. Sublimation Transfer(ST) and Electrophotography. In spite of much effort,most of those were insufficient for getting a good hard copy. Developing sufficient ST recording media, Dai Nippon Printing started ST recording media business in 1986. It was the first manufacturing scale production and sale of ST recording media in the world. Nowadays ST technology is known for its advantages: high image quality, consistency from copy to copy, smooth tone-reproduction from high-light to maximum density, and easiness to use. In the following paper progress of ST recording media and the present situation and future markets of the media will be presented.

  8. Gene transfer strategies for improving radiolabeled peptide imaging and therapy

    International Nuclear Information System (INIS)

    Rogers, B.E.; Buchsbaum, D.J.; Zinn, K.R.

    2000-01-01

    Utilization of molecular biology techniques offers attractive options in nuclear medicine for improving cancer imaging and therapy with radiolabeled peptides. Two of these options include utilization of phage-panning to identify novel tumor specific peptides or single chain antibodies and gene transfer techniques to increase the antibodies and gene transfer techniques to increase the number of antigen/receptor sites expressed on malignant cells. The group has focused on the latter approach for improving radiolabeled peptide imaging and therapy. The most widely used gene transfer vectors in clinical gene therapy trials include retrovirus, cationic lipids and adenovirus. It has been utilized adenovirus vectors for gene transfer because of their ability to accomplish efficient in vivo gene transfer. Adenovirus vectors encoding the genes for a variety of antigens/receptors (carcinoembryonic antigen, gastrin-releasing peptide receptor, somatostatin receptor subtype 2 (SSTr2) have all shown that their expression is increased on cancer cells both in vitro and in vivo following adenovirus infection. Of particular interest has been the adenovirus encoding for SSTr2 (AdCMVSSTr2). Various radioisotopes have been attached to somatostatin analogues for imaging and therapy of SSTr2-positive tumors both clinically and in animal models. The use of these analogues in combination with AdCMVSSTr2 is a promising approach for improving the detection sensitivity and therapeutic efficacy of these radiolabeled peptides against solid tumors. In addition, it has been proposed the use of SSTr2 as a marker for imaging the expression of another cancer therapeutic transgene (e.g. cytosine deaminase, thymidine kinase) encoded within the same vector. This would allow for non-invasive monitoring of gene delivery to tumor sites

  9. Method for estimating modulation transfer function from sample images.

    Science.gov (United States)

    Saiga, Rino; Takeuchi, Akihisa; Uesugi, Kentaro; Terada, Yasuko; Suzuki, Yoshio; Mizutani, Ryuta

    2018-02-01

    The modulation transfer function (MTF) represents the frequency domain response of imaging modalities. Here, we report a method for estimating the MTF from sample images. Test images were generated from a number of images, including those taken with an electron microscope and with an observation satellite. These original images were convolved with point spread functions (PSFs) including those of circular apertures. The resultant test images were subjected to a Fourier transformation. The logarithm of the squared norm of the Fourier transform was plotted against the squared distance from the origin. Linear correlations were observed in the logarithmic plots, indicating that the PSF of the test images can be approximated with a Gaussian. The MTF was then calculated from the Gaussian-approximated PSF. The obtained MTF closely coincided with the MTF predicted from the original PSF. The MTF of an x-ray microtomographic section of a fly brain was also estimated with this method. The obtained MTF showed good agreement with the MTF determined from an edge profile of an aluminum test object. We suggest that this approach is an alternative way of estimating the MTF, independently of the image type. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Performance assessment of imaging plates for the JHR transfer Neutron Imaging System

    Science.gov (United States)

    Simon, E.; Guimbal, P. AB(; )

    2018-01-01

    The underwater Neutron Imaging System to be installed in the Jules Horowitz Reactor (JHR-NIS) is based on a transfer method using a neutron activated beta-emitter like Dysprosium. The information stored in the converter is to be offline transferred on a specific imaging system, still to be defined. Solutions are currently under investigation for the JHR-NIS in order to anticipate the disappearance of radiographic films commonly used in these applications. We report here the performance assessment of Computed Radiography imagers (Imaging Plates) performed at LLB/Orphée (CEA Saclay). Several imaging plate types are studied, in one hand in the configuration involving an intimate contact with an activated dysprosium foil converter: Fuji BAS-TR, Fuji UR-1 and Carestream Flex XL Blue imaging plates, and in the other hand by using a prototypal imaging plate doped with dysprosium and thus not needing any contact with a separate converter foil. The results for these imaging plates are compared with those obtained with gadolinium doped imaging plate used in direct neutron imaging (Fuji BAS-ND). The detection performances of the different imagers are compared regarding resolution and noise. The many advantages of using imaging plates over radiographic films (high sensitivity, linear response, high dynamic range) could palliate its lower intrinsic resolution.

  11. Conjugate Image Theory Applied on Capacitive Wireless Power Transfer

    Directory of Open Access Journals (Sweden)

    Ben Minnaert

    2017-01-01

    Full Text Available Wireless power transfer using a magnetic field through inductive coupling is steadily entering the market in a broad range of applications. However, for certain applications, capacitive wireless power transfer using electric coupling might be preferable. In order to obtain a maximum power transfer efficiency, an optimal compensation network must be designed at the input and output ports of the capacitive wireless link. In this work, the conjugate image theory is applied to determine this optimal network as a function of the characteristics of the capacitive wireless link, as well for the series as for the parallel topology. The results are compared with the inductive power transfer system. Introduction of a new concept, the coupling function, enables the description of the compensation network of both an inductive and a capacitive system in two elegant equations, valid for the series and the parallel topology. This approach allows better understanding of the fundamentals of the wireless power transfer link, necessary for the design of an efficient system.

  12. L'etat, C'est Moi: Why provincial Intra-governmental disputes in ...

    African Journals Online (AJOL)

    L'etat, C'est Moi: Why provincial Intra-governmental disputes in Shout Africa remain ungoverned by the final constitution and the Intergovernmental Relations Framework Act - and how we can best resolve them.

  13. 13CHD2–CEST NMR spectroscopy provides an avenue for studies of conformational exchange in high molecular weight proteins

    International Nuclear Information System (INIS)

    Rennella, Enrico; Huang, Rui; Velyvis, Algirdas; Kay, Lewis E.

    2015-01-01

    An NMR experiment for quantifying slow (millisecond) time-scale exchange processes involving the interconversion between visible ground state and invisible, conformationally excited state conformers is presented. The approach exploits chemical exchange saturation transfer (CEST) and makes use of 13 CHD 2 methyl group probes that can be readily incorporated into otherwise highly deuterated proteins. The methodology is validated with an application to a G48A Fyn SH3 domain that exchanges between a folded conformation and a sparsely populated and transiently formed unfolded ensemble. Experiments on a number of different protein systems, including a 360 kDa half-proteasome, establish that the sensitivity of this 13 CHD 2 13 C–CEST technique can be upwards of a factor of 5 times higher than for a previously published 13 CH 3 13 C–CEST approach (Bouvignies and Kay in J Biomol NMR 53:303–310, 2012), suggesting that the methodology will be powerful for studies of conformational exchange in high molecular weight proteins

  14. Image Signal Transfer Method in Artificial Retina using Laser

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, I.Y.; Lee, B.H.; Kim, S.J. [Seoul National University, Seoul (Korea)

    2002-05-01

    Recently, the research on artificial retina for the blind is active. In this paper a new optical link method for the retinal prosthesis is proposed. Laser diode system was chosen to transfer image into the eye in this project and the new optical system was designed and evaluated. The use of laser diode array in artificial retina system makes system simple for lack of signal processing part inside of the eyeball. Designed optical system is enough to focus laser diode array on photodiode array in 20X20 application. (author). 11 refs., 7 figs., 2 tabs.

  15. MR and magnetisation transfer imaging in cirrhotic and fatty livers

    International Nuclear Information System (INIS)

    Alanen, A.; Komu, M.; Leino, R.; Toikkanen, S.

    1998-01-01

    Purpose: To determine whether low-field MR fat/water separation and magnetisation transfer (MT) techniques are useful in studying the livers of patients with parenchymal liver diseases in vivo. Material and Methods: MR and MT imaging of the liver in 33 patients (14 with primary biliary cirrhosis, 15 with alcohol-induced liver disease, and 4 with fatty liver) was performed by means of the fat/water separation technique at 0.1 T. The relaxation time T1 and the MT contrast (MTC) parameter of liver and spleen tissue were measured, and the relative proton density fat content N(%) and MTC of the liver were calculated from the separate fat and water images. The value of N(%) was also compared with the percentage of fatty hepatocytes at histology. Results: The relaxation rate R1 of liver measured from the magnitude image, and the difference in the value of MTC measured form the water image compared with the one measured from the fat and water magnitude image, both depended linearly on the value of N(%). The value of N(%) correlated significantly with the percentage of the fatty hepatocytes. In in vivo fatty tissue, fat infiltration increased both the observed relaxation rate R1 and the measured magnetisation ratio (the steady state magnetisation M s divided by the equilibrium magnetisation M o , M s /M o ) and consequently decreased the MT efficiency measured in a magnitude MR image. The amount of liver fibrosis did not correlate with the value of MTC measured after fat separation. Conclusion: Our results in studying fatty livers with MR imaging and the MT method show that the fat/water separation gives more reliable parametric results. Characterisation of liver cirrhosis by means of the MTC parameter is not reliable, even after fat separation. (orig.)

  16. Estudos de cestóides de peixes do Brasil

    Directory of Open Access Journals (Sweden)

    A. Arandas Rego

    1974-01-01

    Full Text Available Os autores iniciam com este trabalho um estudo sistemático de determinação dos cestóides de peixes depositados na Coleção helmintológica do Instituto Oswaldo Cruz. São referidas ou descritas as seguintes espécies e seus hospedeiros: Schizochoerus liguloideus (Diesing, 1850 e Nesolecithus janicki Posche, 1922, ambas de Arapaima gigas (Cuvier, (piracuru; Gyrocotyle meandrica Herrera, 1946, de Callorhynchus callorhynchus (L., (quimera; Acanthobothrium dasybati Yamaguti, 1934 e Pterobothriidae não identificado, de uma arraia não determinada; três tipos larvares de trypanorrhyncha e um de Proteocephalidea, de Cynoscion striatus (Cuv. e C. leiarchus (pescadinha; Proteocephalus jandia Woodland, 1934, de um bagre não determinado. Monticellia siluri (Fuhrmann, 1916 e Amphoteromorphus praeputialis sp. n. de Cetopsis caecutiens e Nomimoscolex magna sp. n. de Pimelodus clarias (mandi.The authors start, with this note, a systematic study for determination of cestodes of fishes of the Helminthological Collection of the Instituto Oswaldo Cruz. The following species and hosts are refered and described: Schizochoerus liguloideus (Diesing, 1850 and Nesolecithus janicki poche, 1922 both of Arapaima gigas (Cuvier; Gyrocotyle meandrica Herrera, 1946 of Callorhynchus callorhynchus (L.,Acanthobothrium dasybati Yamaguti, 1934 and Pterobothriidae unidentified, of an indeterminate ray; three types of larvae of Trypanorrhyncha and type of Proteocephalidea, of Cynoscion striatus (Cuv. and C. leiarchus; Proteocephalus jandia Woodland, 1934 of an indeterminate catfish; Monticellia siluri (Furhrmann, 1916 and Amphoteromorphus praeputialis sp. n. of Cetopsis caecutiens and Nomimoscolex magna sp. n. of Pimelodus clarias.

  17. Magnetization transfer on T2-weighted image : magnetization Transfer ratios in normal brain and cerebral lesions

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Myung Kwan; Roh, Hong Gee; Suh, Chang Hae; Cho, Young Kook; Kim, Hyung Jin; Kim, Jin Hee; Kim, Sung Tae; Choi, Sung Kyu [Inha Univ. College of Medicine, Incheon (Korea, Republic of)

    1998-07-01

    To evaluate the magnetization transfer ratio(MTR) of various normal structures and pathologic lesions, as seen on magnetization transfer T2-weighted images (MT+T2WI). Materials and Methods : In ten normal volunteers, T2-weighted images without MT (MT-T2WI) and with MT(MT+T2WI) were obtained. Off-set pulses used in MT+T2WI were 400, 600, 1000, 1500, and 2000Hz. In 60 clinical cases infarction(n=10), brain tumors(n=5), traumatic hematomas(n=5), other hematomas(n=3) vascular malformation(n=2) white matter disease(n=2) normal(n=31) and others(n=2), both MT-T2WI and MT+T2WI images were obtained using an off-set pulse of 600 Hz. In all volunteers and patients, MTR in various normal brain parenchyma and abnormal areas was measured. Results : The MTRs of white and gray matter were 48% and 45% respectively at 400 Hz, 26% and 22% at 600Hz, 12% and 11% of 1000Hz, 10% and 9% 1500HZ, and 9% and 8% at 2000Hz of RF. The MTR of CSF was 43% at 400 Hz of off-resonance RF, while the contrast resolution of T2WI was poor. An off-resonance of 600Hz appeared to be the optimal frequency. In diseased areas,MTRs varied but were usually similar to or lower than those of brain parenchyma. Conclusion : The optimal off-resonance RF on MT+T2WI appears to be 600 Hz for relatively high MTR of brain parenchyma and low MTR of CSF,in which MTRs of white and gray matter were 26% and 22%, respectively, of 600Hz off-set pulse. The MTRs of cerebral lesions varied and further studies of various cerebral lesions are needed.

  18. Transfer and conversion of images based on EIT in atom vapor.

    Science.gov (United States)

    Cao, Mingtao; Zhang, Liyun; Yu, Ya; Ye, Fengjuan; Wei, Dong; Guo, Wenge; Zhang, Shougang; Gao, Hong; Li, Fuli

    2014-05-01

    Transfer and conversion of images between different wavelengths or polarization has significant applications in optical communication and quantum information processing. We demonstrated the transfer of images based on electromagnetically induced transparency (EIT) in a rubidium vapor cell. In experiments, a 2D image generated by a spatial light modulator is used as a coupling field, and a plane wave served as a signal field. We found that the image carried by coupling field could be transferred to that carried by signal field, and the spatial patterns of transferred image are much better than that of the initial image. It also could be much smaller than that determined by the diffraction limit of the optical system. We also studied the subdiffraction propagation for the transferred image. Our results may have applications in quantum interference lithography and coherent Raman spectroscopy.

  19. Quantitative description of proton exchange processes between water and endogenous and exogenous agents for WEX, CEST, and APT experiments.

    Science.gov (United States)

    Zhou, Jinyuan; Wilson, David A; Sun, Phillip Zhe; Klaus, Judith A; Van Zijl, Peter C M

    2004-05-01

    The proton exchange processes between water and solutes containing exchangeable protons have recently become of interest for monitoring pH effects, detecting cellular mobile proteins and peptides, and enhancing the detection sensitivity of various low-concentration endogenous and exogenous species. In this work, the analytic expressions for water exchange (WEX) filter spectroscopy, chemical exchange-dependent saturation transfer (CEST), and amide proton transfer (APT) experiments are derived by the use of Bloch equations with exchange terms. The effects of the initial states for the system, the difference between a steady state and a saturation state, and the relative contributions of the forward and backward exchange processes are discussed. The theory, in combination with numerical calculations, provides a useful tool for designing experimental schemes and assessing magnetization transfer (MT) processes between water protons and solvent-exchangeable protons. As an example, the case of endogenous amide proton exchange in the rat brain at 4.7 T is analyzed in detail. Copyright 2004 Wiley-Liss, Inc.

  20. Image transfer by cascaded stack of photonic crystal and air layers

    NARCIS (Netherlands)

    Shen, C.; Michielsen, K.; Raedt, H. De

    2006-01-01

    We demonstrate image transfer by a cascaded stack consisting of two and three triangular-lattice photonic crystal slabs separated by air. The quality of the image transfered by the stack is sensitive to the air/photonic crystal interface termination and the frequency. Depending on the frequency and

  1. B1 -sensitivity analysis of quantitative magnetization transfer imaging.

    Science.gov (United States)

    Boudreau, Mathieu; Stikov, Nikola; Pike, G Bruce

    2018-01-01

    To evaluate the sensitivity of quantitative magnetization transfer (qMT) fitted parameters to B 1 inaccuracies, focusing on the difference between two categories of T 1 mapping techniques: B 1 -independent and B 1 -dependent. The B 1 -sensitivity of qMT was investigated and compared using two T 1 measurement methods: inversion recovery (IR) (B 1 -independent) and variable flip angle (VFA), B 1 -dependent). The study was separated into four stages: 1) numerical simulations, 2) sensitivity analysis of the Z-spectra, 3) healthy subjects at 3T, and 4) comparison using three different B 1 imaging techniques. For typical B 1 variations in the brain at 3T (±30%), the simulations resulted in errors of the pool-size ratio (F) ranging from -3% to 7% for VFA, and -40% to > 100% for IR, agreeing with the Z-spectra sensitivity analysis. In healthy subjects, pooled whole-brain Pearson correlation coefficients for F (comparing measured double angle and nominal flip angle B 1 maps) were ρ = 0.97/0.81 for VFA/IR. This work describes the B 1 -sensitivity characteristics of qMT, demonstrating that it varies substantially on the B 1 -dependency of the T 1 mapping method. Particularly, the pool-size ratio is more robust against B 1 inaccuracies if VFA T 1 mapping is used, so much so that B 1 mapping could be omitted without substantially biasing F. Magn Reson Med 79:276-285, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  2. Transferring Biomarker into Molecular Probe: Melanin Nanoparticle as a Naturally Active Platform for Multimodality Imaging

    OpenAIRE

    Fan, Quli; Cheng, Kai; Hu, Xiang; Ma, Xiaowei; Zhang, Ruiping; Yang, Min; Lu, Xiaomei; Xing, Lei; Huang, Wei; Gambhir, Sanjiv Sam; Cheng, Zhen

    2014-01-01

    Developing multifunctional and easily prepared nanoplatforms with integrated different modalities is highly challenging for molecular imaging. Here, we report the successful transfer of an important molecular target, melanin, into a novel multimodality imaging nanoplatform. Melanin is abundantly expressed in melanotic melanomas and thus has been actively studied as a target for melanoma imaging. In our work, the multifunctional biopolymer nanoplatform based on ultrasmall (

  3. CHARACTERIZING RESIDUE TRANSFER EFFICIENCIES USING A FLUORESCENT IMAGING TECHNIQUE

    Science.gov (United States)

    To reduce the uncertainty associated with current estimates of children's exposure to pesticides by dermal contact and indirect ingestion, residue transfer data are required. Prior to conducting exhaustive studies, a screening study to identify the important parameters for chara...

  4. Lecture actentielle dans Trop c'est trop de Protais Asseng | IKANGA ...

    African Journals Online (AJOL)

    La naissance de cet enfant lui conférait le titre de "Papa national" Bakony symbolise la recherche de bonheur sur le dos d'un humain. C'est de l'exploitation de la femme par l'homme. Mais la multipare Bissabey, son épouse, n'est pas de son avis. Cette instrumentalisation est alors la pomme de discorde entre le couple et ...

  5. , TOUCHE PAS À MA TERRE, I ! ' C'EST MA VIE !

    International Development Research Centre (IDRC) Digital Library (Canada)

    nouvelles lois afin d'assurer un plus grand contrôle sur leurs terres arables. C'est ... phénomène, du respect des réglementations locales de gestion foncière. ...... imposé dans la mesure où, l'Etat ayant octroyé les différents permis à. Newcrest ...

  6. Transforming thymidine into a magnetic resonance imaging probe for monitoring gene expression.

    Science.gov (United States)

    Bar-Shir, Amnon; Liu, Guanshu; Liang, Yajie; Yadav, Nirbhay N; McMahon, Michael T; Walczak, Piotr; Nimmagadda, Sridhar; Pomper, Martin G; Tallman, Keri A; Greenberg, Marc M; van Zijl, Peter C M; Bulte, Jeff W M; Gilad, Assaf A

    2013-01-30

    Synthetic chemistry has revolutionized the understanding of many biological systems. Small compounds that act as agonists and antagonists of proteins, and occasionally as imaging probes, have contributed tremendously to the elucidation of many biological pathways. Nevertheless, the function of thousands of proteins is still elusive, and designing new imaging probes remains a challenge. Through screening and characterization, we identified a thymidine analogue as a probe for imaging the expression of herpes simplex virus type-1 thymidine kinase (HSV1-TK). To detect the probe, we used chemical exchange saturation transfer magnetic resonance imaging (CEST-MRI), in which a dynamic exchange process between an exchangeable proton and the surrounding water protons is used to amplify the desired contrast. Initially, five pyrimidine-based molecules were recognized as putative imaging agents, since their exchangeable imino protons resonate at 5-6 ppm from the water proton frequency and their detection is therefore less affected by endogenous CEST contrast or confounded by direct water saturation. Increasing the pK(a) value of the imino proton by reduction of its 5,6-double bond results in a significant reduction of the exchange rate (k(ex)) between this proton and the water protons. This reduced k(ex) of the dihydropyrimidine nucleosides fulfills the "slow to intermediate regime" condition for generating high CEST-MRI contrast. Consequently, we identified 5-methyl-5,6-dihydrothymidine as the optimal probe and demonstrated its feasibility for in vivo imaging of HSV1-TK. In light of these findings, this new approach can be generalized for designing specific probes for the in vivo imaging of a variety of proteins and enzymes.

  7. Fluorescence resonance energy transfer imaging of CFP/YFP labeled NDH in cyanobacterium cell

    International Nuclear Information System (INIS)

    Ji Dongmei; Lv Wei; Huang Zhengxi; Xia Andong; Xu Min; Ma Weimin; Mi Hualing; Ogawa Teruo

    2007-01-01

    The laser confocal scanning microscopy combined with time-correlated single photon counting imaging technique to obtain fluorescence intensity and fluorescence lifetime images for fluorescence resonance energy transfer measurement is reported. Both the fluorescence lifetime imaging microscopy (FLIM) and intensity images show inhomogeneous cyan fluorescent protein and yellow fluorescent protein (CFP /YFP) expression or inhomogeneous energy transfer between CFP and YFP over whole cell. The results presented in this work show that FLIM could be a potential method to reveal the structure-function behavior of NAD(P)H dehydrogenase complexes in living cell

  8. Pediatric Trauma Transfer Imaging Inefficiencies-Opportunities for Improvement with Cloud Technology.

    Science.gov (United States)

    Puckett, Yana; To, Alvin

    2016-01-01

    This study examines the inefficiencies of radiologic imaging transfers from one hospital to the other during pediatric trauma transfers in an era of cloud based information sharing. Retrospective review of all patients transferred to a pediatric trauma center from 2008-2014 was performed. Imaging was reviewed for whether imaging accompanied the patient, whether imaging was able to be uploaded onto computer for records, whether imaging had to be repeated, and whether imaging obtained at outside hospitals (OSH) was done per universal pediatric trauma guidelines. Of the 1761 patients retrospectively reviewed, 559 met our inclusion criteria. Imaging was sent with the patient 87.7% of the time. Imaging was unable to be uploaded 31.9% of the time. CT imaging had to be repeated 1.8% of the time. CT scan was not done per universal pediatric trauma guidelines 1.2% of the time. Our study demonstrated that current imaging transfer is inefficient, leads to excess ionizing radiation, and increased healthcare costs. Universal implementation of cloud based radiology has the potential to eliminate excess ionizing radiation to children, improve patient care, and save cost to healthcare system.

  9. Pediatric Trauma Transfer Imaging Inefficiencies—Opportunities for Improvement with Cloud Technology

    Directory of Open Access Journals (Sweden)

    Yana Puckett

    2016-02-01

    Full Text Available BACKGROUND: This study examines the inefficiencies of radiologic imaging transfers from one hospital to the other during pediatric trauma transfers in an era of cloud based information sharing. METHODS: Retrospective review of all patients transferred to a pediatric trauma center from 2008–2014 was performed. Imaging was reviewed for whether imaging accompanied the patient, whether imaging was able to be uploaded onto computer for records, whether imaging had to be repeated, and whether imaging obtained at outside hospitals (OSH was done per universal pediatric trauma guidelines. RESULTS: Of the 1761 patients retrospectively reviewed, 559 met our inclusion criteria. Imaging was sent with the patient 87.7% of the time. Imaging was unable to be uploaded 31.9% of the time. CT imaging had to be repeated 1.8% of the time. CT scan was not done per universal pediatric trauma guidelines 1.2% of the time. CONCLUSION: Our study demonstrated that current imaging transfer is inefficient, leads to excess ionizing radiation, and increased healthcare costs. Universal implementation of cloud based radiology has the potential to eliminate excess ionizing radiation to children, improve patient care, and save cost to healthcare system.

  10. Quantitative Magnetization Transfer Imaging in Human Brain at 3 T via Selective Inversion Recovery

    OpenAIRE

    Dortch, Richard D.; Li, Ke; Gochberg, Daniel F.; Welch, E. Brian; Dula, Adrienne N.; Tamhane, Ashish A.; Gore, John C.; Smith, Seth A.

    2011-01-01

    Quantitative magnetization transfer imaging yields indices describing the interactions between free water protons and immobile, macromolecular protons—including the macromolecular to free pool size ratio (PSR) and the rate of magnetization transfer between pools kmf. This study describes the first implementation of the selective inversion recovery quantitative magnetization transfer method on a clinical 3.0-T scanner in human brain in vivo. Selective inversion recovery data were acquired at 1...

  11. Multimodality imaging: transfer and fusion of SPECT and MRI data

    International Nuclear Information System (INIS)

    Knesaurek, K.

    1994-01-01

    Image fusion is a technique which offers the best of both worlds. It unites the two basic types of medical images: functional body images(PET or SPECT scans), which provide physiological information, and structural images (CT or MRI), which provide an anatomic map of the body. Control-point based registration technique was developed and used. Tc-99m point sources were used as external markers in SPECT studies while, for MRI and CT imaging only anatomic landmarks were used as a control points. The MRI images were acquired on GE Signa 1.2 system and CT data on a GE 9800 scanner. SPECT studies were performed 1h after intravenous injection of the 740 MBq of the Tc-99m-HMPAO on the triple-headed TRIONIX gamma camera. B-spline and bilinear interpolation were used for the rotation, scaling and translation of the images. In the process of creation of a single composite image, in order to retain information from the individual images, MRI (or CT) image was scaled to one color range and a SPECT image to another. In some situations the MRI image was kept black-and-white while the SPECT image was pasted on top of it in 'opaque' mode. Most errors which propagate through the matching process are due to sample size, imperfection of the acquisition system, noise and interpolations used. Accuracy of the registration was investigated by SPECT-CT study performed on a phantom study. The results has shown that accuracy of the matching process is better, or at worse, equal to 2 mm. (author)

  12. Amide proton transfer imaging of high intensity focused ultrasound-treated tumor tissue

    NARCIS (Netherlands)

    Hectors, S.J.C.G.; Jacobs, I.; Strijkers, G.J.; Nicolay, K.

    2014-01-01

    Purpose: In this study, the suitability of amide proton transfer (APT) imaging as a biomarker for the characterization of high intensity focused ultrasound (HIFU)-treated tumor tissue was assessed. Methods: APT imaging was performed on tumor-bearing mice before (n=15), directly after (n=15) and at 3

  13. Amide Proton Transfer Imaging of High Intensity Focused Ultrasound-Treated Tumor Tissue

    NARCIS (Netherlands)

    Hectors, Stefanie J. C. G.; Jacobs, Igor; Strijkers, Gustav J.; Nicolay, Klaas

    2014-01-01

    PurposeIn this study, the suitability of amide proton transfer (APT) imaging as a biomarker for the characterization of high intensity focused ultrasound (HIFU)-treated tumor tissue was assessed. MethodsAPT imaging was performed on tumor-bearing mice before (n=15), directly after (n=15) and at 3

  14. Deep Learning- and Transfer Learning-Based Super Resolution Reconstruction from Single Medical Image

    Directory of Open Access Journals (Sweden)

    YiNan Zhang

    2017-01-01

    Full Text Available Medical images play an important role in medical diagnosis and research. In this paper, a transfer learning- and deep learning-based super resolution reconstruction method is introduced. The proposed method contains one bicubic interpolation template layer and two convolutional layers. The bicubic interpolation template layer is prefixed by mathematics deduction, and two convolutional layers learn from training samples. For saving training medical images, a SIFT feature-based transfer learning method is proposed. Not only can medical images be used to train the proposed method, but also other types of images can be added into training dataset selectively. In empirical experiments, results of eight distinctive medical images show improvement of image quality and time reduction. Further, the proposed method also produces slightly sharper edges than other deep learning approaches in less time and it is projected that the hybrid architecture of prefixed template layer and unfixed hidden layers has potentials in other applications.

  15. Intelligent Image Recognition System for Marine Fouling Using Softmax Transfer Learning and Deep Convolutional Neural Networks

    Directory of Open Access Journals (Sweden)

    C. S. Chin

    2017-01-01

    Full Text Available The control of biofouling on marine vessels is challenging and costly. Early detection before hull performance is significantly affected is desirable, especially if “grooming” is an option. Here, a system is described to detect marine fouling at an early stage of development. In this study, an image of fouling can be transferred wirelessly via a mobile network for analysis. The proposed system utilizes transfer learning and deep convolutional neural network (CNN to perform image recognition on the fouling image by classifying the detected fouling species and the density of fouling on the surface. Transfer learning using Google’s Inception V3 model with Softmax at last layer was carried out on a fouling database of 10 categories and 1825 images. Experimental results gave acceptable accuracies for fouling detection and recognition.

  16. Smear correction of highly variable, frame-transfer CCD images with application to polarimetry.

    Science.gov (United States)

    Iglesias, Francisco A; Feller, Alex; Nagaraju, Krishnappa

    2015-07-01

    Image smear, produced by the shutterless operation of frame-transfer CCD detectors, can be detrimental for many imaging applications. Existing algorithms used to numerically remove smear do not contemplate cases where intensity levels change considerably between consecutive frame exposures. In this report, we reformulate the smearing model to include specific variations of the sensor illumination. The corresponding desmearing expression and its noise properties are also presented and demonstrated in the context of fast imaging polarimetry.

  17. Optimization of 7-T Chemical Exchange Saturation Transfer Parameters for Validation of Glycosaminoglycan and Amide Proton Transfer of Fibroglandular Breast Tissue

    NARCIS (Netherlands)

    Dula, Adrienne N.; Dewey, Blake E.; Arlinghaus, Lori R.; Williams, Jason M.; Klomp, DWJ; Yankeelov, Thomas E.; Smith, Seth

    Purpose: To (a) implement simulation-optimized chemical exchange saturation transfer (CEST) measurements sensitive to amide proton transfer (APT) and glycosaminoglycan (GAG) hydroxyl proton transfer effects in the human breast at 7 T and (b) determine the reliability of these techniques for

  18. Soil transference patterns on bras: Image processing and laboratory dragging experiments.

    Science.gov (United States)

    Murray, Kathleen R; Fitzpatrick, Robert W; Bottrill, Ralph S; Berry, Ron; Kobus, Hilton

    2016-01-01

    In a recent Australian homicide, trace soil on the victim's clothing suggested she was initially attacked in her front yard and not the park where her body was buried. However the important issue that emerged during the trial was how soil was transferred to her clothing. This became the catalyst for designing a range of soil transference experiments (STEs) to study, recognise and classify soil patterns transferred onto fabric when a body is dragged across a soil surface. Soil deposits of interest in this murder were on the victim's bra and this paper reports the results of anthropogenic soil transfer to bra-cups and straps caused by dragging. Transfer patterns were recorded by digital photography and photomicroscopy. Eight soil transfer patterns on fabric, specific to dragging as the transfer method, appeared consistently throughout the STEs. The distinctive soil patterns were largely dependent on a wide range of soil features that were measured and identified for each soil tested using X-ray Diffraction and Non-Dispersive Infra-Red analysis. Digital photographs of soil transfer patterns on fabric were analysed using image processing software to provide a soil object-oriented classification of all soil objects with a diameter of 2 pixels and above transferred. Although soil transfer patterns were easily identifiable by naked-eye alone, image processing software provided objective numerical data to support this traditional (but subjective) interpretation. Image software soil colour analysis assigned a range of Munsell colours to identify and compare trace soil on fabric to other trace soil evidence from the same location; without requiring a spectrophotometer. Trace soil from the same location was identified by linking soils with similar dominant and sub-dominant Munsell colour peaks. Image processing numerical data on the quantity of soil transferred to fabric, enabled a relationship to be discovered between soil type, clay mineralogy (smectite), particle size and

  19. Calculation of playback signals from MFM images using transfer functions

    NARCIS (Netherlands)

    Vellekoop, S.J.L.; Abelmann, Leon; Porthun, S.; Lodder, J.C.; Miles, J.J.

    1999-01-01

    Magnetic force microscopy has proven to be a suitable tool for analysis of high-density magnetic recording materials. Comparison of the MFM image of a written signal with the actual read-back signal of the recording system can give valuable insight in the recording properties of both heads and

  20. Image quality transfer and applications in diffusion MRI

    DEFF Research Database (Denmark)

    Alexander, Daniel C.; Zikic, Darko; Ghosh, Aurobrata

    2017-01-01

    and the uniquely rich diffusion MRI data set from the human connectome project (HCP). Results highlight potential benefits of IQT in both brain connectivity mapping and microstructure imaging. In brain connectivity mapping, IQT reveals, from standard data sets, thin connection pathways that tractography normally...

  1. Transfer function analysis of positron-emitting tracer imaging system (PETIS) data

    International Nuclear Information System (INIS)

    Keutgen, N.; Matsuhashi, S.; Mizuniwa, C.; Ito, T.; Fujimura, T.; Ishioka, N.S.; Watanabe, S.; Sekine, T.; Uchida, H.; Hashimoto, S.

    2002-01-01

    Quantitative analysis of the two-dimensional image data obtained with the positron-emitting tracer imaging system (PETIS) for plant physiology has been carried out using a transfer function analysis method. While a cut leaf base of Chinese chive (Allium tuberosum Rottler) or a cut stem of soybean (Glycine max L.) was immersed in an aqueous solution containing the [ 18 F] F - ion or [ 13 N]NO 3 - ion, tracer images of the leaf of Chinese chive and the trifoliate of soybean were recorded with PETIS. From the time sequence of images, the tracer transfer function was estimated from which the speed of tracer transport and the fraction moved between specified image positions were deduced

  2. Modulation transfer function cascade model for a sampled IR imaging system.

    Science.gov (United States)

    de Luca, L; Cardone, G

    1991-05-01

    The performance of the infrared scanning radiometer (IRSR) is strongly stressed in convective heat transfer applications where high spatial frequencies in the signal that describes the thermal image are present. The need to characterize more deeply the system spatial resolution has led to the formulation of a cascade model for the evaluation of the actual modulation transfer function of a sampled IR imaging system. The model can yield both the aliasing band and the averaged modulation response for a general sampling subsystem. For a line scan imaging system, which is the case of a typical IRSR, a rule of thumb that states whether the combined sampling-imaging system is either imaging-dependent or sampling-dependent is proposed. The model is tested by comparing it with other noncascade models as well as by ad hoc measurements performed on a commercial digitized IRSR.

  3. Development of a system for transferring images via a network: supporting a regional liaison.

    Science.gov (United States)

    Mihara, Naoki; Manabe, Shiro; Takeda, Toshihiro; Shinichirou, Kitamura; Junichi, Murakami; Kouji, Kiso; Matsumura, Yasushi

    2013-01-01

    We developed a system that transfers images via network and started using them in our hospital's PACS (Picture Archiving and Communication Systems) in 2006. We are pleased to report that the system has been re-developed and has been running so that there will be a regional liaison in the future. It has become possible to automatically transfer images simply by selecting the destination hospital that is registered in advance at the relay server. The gateway of this system can send images to a multi-center, relay management server, which receives the images and resends them. This system has the potential to be useful for image exchange, and to serve as a regional medical liaison.

  4. Imaging living central neurones using viral gene transfer.

    Science.gov (United States)

    Teschemacher, A G; Paton, J F R; Kasparov, S

    2005-01-02

    Studies of central neurones and other cellular components of the brain, such as glial and vascular cells, can be greatly advanced by the use of the modern optical techniques such as confocal live cell imaging. Fluorescent proteins have allowed imaging of particular cell types or intracellular elements to be visualised and distinguished from irrelevant background structures. To introduce the genetic information encoding for fluorescent proteins into relevant cellular targets, molecular tools are required. Viral vectors are one of the best ways of gene delivery into differentiated postnatal brain neurones and glia. Current progress in this field allows targeting of various cell types and therefore makes it possible to express a variety of fluorescent constructs in selected subpopulations of neurones, for example. In this review, we will discuss and compare the properties of the most popular viral gene delivery systems and the advantages of different brain cell preparations to illustrate how they can be used for high-resolution live cell confocal imaging in order to study new aspects of central nervous system (CNS) structure and function.

  5. Efficient nonlinear registration of 3D images using high order co-ordinate transfer functions.

    Science.gov (United States)

    Barber, D C

    1999-01-01

    There is an increasing interest in image registration for a variety of medical imaging applications. Image registration is achieved through the use of a co-ordinate transfer function (CTF) which maps voxels in one image to voxels in the other image, including in the general case changes in mapped voxel intensity. If images of the same subject are to be registered the co-ordinate transfer function needs to implement a spatial transformation consisting of a displacement and a rigid rotation. In order to achieve registration a common approach is to choose a suitable quality-of-registration measure and devise a method for the efficient generation of the parameters of the CTF which minimize this measure. For registration of images from different subjects more complex transforms are required. In general function minimization is too slow to allow the use of CTFs with more than a small number of parameters. However, provided the images are from the same modality and the CTF can be expanded in terms of an appropriate set of basis functions this paper will show how relatively complex CTFs can be used for registration. The use of increasingly complex CTFs to minimize the within group standard deviation of a set of normal single photon emission tomography brain images is used to demonstrate the improved registration of images from different subjects using CTFs of increasing complexity.

  6. Telemedicine using an image transfer system in the treatment of neurosurgical emergent cases

    International Nuclear Information System (INIS)

    Saito, Atsushi; Numagami, Yoshihiro; Kamiyama, Hironaga; Furuno, Yuuichi; Nishimura, Shinjitsu; Nishijima, Michiharu

    2007-01-01

    Our department is located in the Tsugaru district, which is famous for heavy snow fall, and the small number of neurosurgeon centers in the urban areas leads to an inadequate distribution of neurosurgeons for patients in this region. Such geographical and social constraints have made it difficult to offer sufficient neurosurgical care to all patients in the region. We describe the usefulness of a telemedicine triage system using an image transfer system in the treatment of neurosurgical emergent cases. Image transfer systems have been installed at our hospital and 11 regional hospitals in the Tsugaru district, and have been utilized for teleconsultation regarding neurosurgical patients via transferred computed tomography images since 1989. Consultations regarding 2,858 cases were directed to our department between 1989 and 2006, including 1,615 cases of stroke, 869 cases of head trauma, 97 cases of brain tumor, and 277 cases with other disorders. 84% of subarachnoid hemorrhage cases and 22% of head trauma cases needed emergent transfer. The state of consciousness in intracerebral hemorrhage, and the state of consciousness and time of consultation in head trauma were statistically significant factors for emergent transfer. The presert telemedicine triage system was useful for ensuring correct diagnosis and appropriate primary neurosurgical care in the regional hospitals without neurosurgical units, resulting in a reinforcement of the relationships among the regional hospitals and the efficient transfer of emergent neurosurgical patients. (author)

  7. Magnetization transfer contrast on gradient echo MR imaging of the temporomandibular joint

    International Nuclear Information System (INIS)

    Niitsu, M.; Hirohata, H.; Yoshioka, H.; Anno, I.; Campeau, N.G.; Itai, Y.

    1995-01-01

    Thirty-nine temporomandibular joints (TMJ) from 20 patients with suspected internal derangements were imaged by a 1.5 T MR imager. The on-resonance binomial magnetization transfer contrast (MTC) pulse was applied to gradient echo images with a dual receiver coil (9 s/section). With the use of an opening device, a series of sequential images were obtained at increments of mouth opening and closing. The tissue signal intensities with (Ms) and without (Mo) MTC were measured and subjective image analysis was performed. Compared with the standard images, MTC technique provided selective signal suppression of disks. The average of Ms/Mo ratio of the disks (0.56) was lower than that of the retrodiskal pad (0.79) and of the effusion (0.89). With MTC technique, fluid conspicuity was superior to standard image. However, no significant superiority was found in disk definition subjectively. (orig.)

  8. Magnetization transfer contrast MR imaging of the knee at 0.3 T

    International Nuclear Information System (INIS)

    Yoshioka, Hiroshi; Onaya, Hiroaki; Niitsu, Mamoru; Anno, Izumi; Itai, Yuji; Nishimura, Hiroshi; Kajiyama, Koji; Masuda, Tomonori; Nakajima, Kotaro.

    1994-01-01

    It has been reported that magnetization transfer contrast (MTC) images were effective in evaluating the articular cartilage. However, only one in vivo study of the articular cartilage in the knee has been demonstrated at 1.5T. The purpose of this study was to evaluate the optimal off-resonance MTC pulse at 0.3T MR imager and assess its clinical usefulness. Five normal volunteers and eleven patients with suspected knee injuries were investigated using off-resonance sinc, gaussian, constant shaped irradiation pulses. All MTC images revealed higher contrast and contrast-to-noise (C/N) ratio between articular cartilage and external reference (saline) in the normal volunteers' knee than conventional gradient recalled echo images. MTC images with the gaussian or sinc shaped pulse were judged superior to those with constant wave pulse because the former images showed a fewer artifact with lower specific absorption rate than the latter images. The sinc MTC images were performed with the lowest SAR. The gaussian MTC images revealed better contrast and C/N between articular cartilage and joint fluid than the sinc MTC images in patients. 3D MTC images using Guassian pulse were also performed within a clinically tolerable imaging time (13 min 39 sec). Thus, MTC images in the knee at 0.3T using off-resonance pulse may be effective to assess knee injury due to better contrast between articular cartilage and joint fluid. (author)

  9. Evaluation of biolistic gene transfer methods in vivo using non-invasive bioluminescent imaging techniques

    Directory of Open Access Journals (Sweden)

    Daniell Henry

    2011-06-01

    Full Text Available Abstract Background Gene therapy continues to hold great potential for treating many different types of disease and dysfunction. Safe and efficient techniques for gene transfer and expression in vivo are needed to enable gene therapeutic strategies to be effective in patients. Currently, the most commonly used methods employ replication-defective viral vectors for gene transfer, while physical gene transfer methods such as biolistic-mediated ("gene-gun" delivery to target tissues have not been as extensively explored. In the present study, we evaluated the efficacy of biolistic gene transfer techniques in vivo using non-invasive bioluminescent imaging (BLI methods. Results Plasmid DNA carrying the firefly luciferase (LUC reporter gene under the control of the human Cytomegalovirus (CMV promoter/enhancer was transfected into mouse skin and liver using biolistic methods. The plasmids were coupled to gold microspheres (1 μm diameter using different DNA Loading Ratios (DLRs, and "shot" into target tissues using a helium-driven gene gun. The optimal DLR was found to be in the range of 4-10. Bioluminescence was measured using an In Vivo Imaging System (IVIS-50 at various time-points following transfer. Biolistic gene transfer to mouse skin produced peak reporter gene expression one day after transfer. Expression remained detectable through four days, but declined to undetectable levels by six days following gene transfer. Maximum depth of tissue penetration following biolistic transfer to abdominal skin was 200-300 μm. Similarly, biolistic gene transfer to mouse liver in vivo also produced peak early expression followed by a decline over time. In contrast to skin, however, liver expression of the reporter gene was relatively stable 4-8 days post-biolistic gene transfer, and remained detectable for nearly two weeks. Conclusions The use of bioluminescence imaging techniques enabled efficient evaluation of reporter gene expression in vivo. Our results

  10. Image transfer with spatial coherence for aberration corrected transmission electron microscopes

    International Nuclear Information System (INIS)

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-01-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field’s components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field’s derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. - Highlights: • The formula of partial coherence for aberration corrected TEM is derived. • Transfer functions are calculated with several residual aberrations. • The calculated transfer function shows the characteristic damping. • The odd-symmetric wave aberrations can cause the attenuation of image via coherence. • The examples of aberration corrected TEM image simulations are shown.

  11. Image transfer with spatial coherence for aberration corrected transmission electron microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Hosokawa, Fumio, E-mail: hosokawa@bio-net.co.jp [BioNet Ltd., 2-3-28 Nishikityo, Tachikwa, Tokyo (Japan); Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503 (Japan); Sawada, Hidetaka [JEOL (UK) Ltd., JEOL House, Silver Court, Watchmead, Welwyn Garden City, Herts AL7 1LT (United Kingdom); Shinkawa, Takao [BioNet Ltd., 2-3-28 Nishikityo, Tachikwa, Tokyo (Japan); Sannomiya, Takumi [Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503 (Japan)

    2016-08-15

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field’s components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field’s derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. - Highlights: • The formula of partial coherence for aberration corrected TEM is derived. • Transfer functions are calculated with several residual aberrations. • The calculated transfer function shows the characteristic damping. • The odd-symmetric wave aberrations can cause the attenuation of image via coherence. • The examples of aberration corrected TEM image simulations are shown.

  12. Digital transfer of non-destructive testing images

    International Nuclear Information System (INIS)

    Nelson, S.

    1996-01-01

    This paper intends to address a possible avenue to assist the Non-Destructive Testing Industry in managing and transferring results to their clients in a more efficient way. Data is sent around the globe in various forms to a multitude of destinations. The problem has been twofold in any industry: how to get the data into a communication network and, how to manage and utilize this data. There are many types of scanners which can digitize the graph which can then be displayed on a computer screen via a software programme. The one presented in this paper has been jointly developed by a Melbourne company, Compu Medics and AGFA Australia. This system can also capture a video signal from Ultrasound Units and display on the screen. The author also explore what can be done with this data. Possibilities are endless and include: sending it via satellite or land line to a remote reader, saving or archiving for future reference and utilising the data base for education

  13. C'est La Vie! The Game of Social Life: Using an Intersectionality Approach to Teach About Privilege and Structural Inequality

    Science.gov (United States)

    Bramesfeld, Kosha D.; Good, Arla

    2016-01-01

    In this article, we present the results of two studies that evaluated an experiential intersectionality awareness activity, "C'est La Vie: The Game of Social Life." For Study 1 (N = 55), we content analyzed students' short answer responses about inequality written before and after playing "C'est La Vie." Study 2 compared a…

  14. Breaking the Barrier to Slow Water Exchange Rates for Optimal Magnetic Resonance Detection of paraCEST Agents.

    Science.gov (United States)

    Fernando, W Shirangi; Martins, André F; Zhao, Piyu; Wu, Yunkou; Kiefer, Garry E; Platas-Iglesias, Carlos; Sherry, A Dean

    2016-03-21

    EuDOTA-tetraamide complexes as paraCEST agents offer an attractive platform for designing biological sensors and responsive agents. The early versions of these agents showed low sensitivity at temperature and power levels suitable for in vivo applications partly due to non-optimal water exchange rates. Here we report two new EuDOTA derivatives having glutamyl-phosphonate side arms that display the slowest water exchange rates of any other paraCEST agent reported so far. The advantages of such systems are demonstrated experimentally both in vitro and in vivo and DFT calculations were performed to help understand the physical-chemical reasons for this interesting behavior.

  15. Magnetization transfer imaging of normal and abnormal testis: preliminary results

    International Nuclear Information System (INIS)

    Tsili, Athina C.; Ntorkou, Alexandra; Maliakas, Vasilios; Argyropoulou, Maria I.; Baltogiannis, Dimitrios; Sylakos, Anastasios; Sofikitis, Nikolaos; Stavrou, Sotirios; Astrakas, Loukas G.

    2016-01-01

    The aim was to determine the magnetization transfer ratio (MTR) of normal testes, possible variations with age and to assess the feasibility of MTR in characterizing various testicular lesions. Eighty-six men were included. A three-dimensional gradient-echo MT sequence was performed, with/without an on-resonance binomial prepulse. MTR was calculated as: (SIo-SIm)/(SIo) x 100 %, where SIm and SIo refers to signal intensities with and without the saturation pulse, respectively. Subjects were classified as: group 1, 20-39 years; group 2, 40-65 years; and group 3, older than 65 years of age. Analysis of variance (ANOVA) followed by the least significant difference test was used to assess variations of MTR with age. Comparison between the MTR of normal testis, malignant and benign testicular lesions was performed using independent-samples t testing. ANOVA revealed differences of MTR between age groups (F = 7.51, P = 0.001). Significant differences between groups 1, 2 (P = 0.011) and 1, 3 (P < 0.001) were found, but not between 2, 3 (P = 0.082). The MTR (in percent) of testicular carcinomas was 55.0 ± 3.2, significantly higher than that of benign lesions (50.3 ± 4.0, P = 0.02) and of normal testes (47.4 ± 2.2, P < 0.001). MTR of normal testes decreases with age. MTR might be helpful in the diagnostic work-up of testicular lesions. (orig.)

  16. Transfer

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne; Aarkrog, Vibe

    Bogen er den første samlede indføring i transfer på dansk. Transfer kan anvendes som praksis-filosofikum. Den giver en systematisk indsigt til den studerende, der spørger: Hvordan kan teoretisk viden bruges til at reflektere over handlinger i situationer, der passer til min fremtidige arbejdsplads?...

  17. Computer Software Configuration Item-Specific Flight Software Image Transfer Script Generator

    Science.gov (United States)

    Bolen, Kenny; Greenlaw, Ronald

    2010-01-01

    A K-shell UNIX script enables the International Space Station (ISS) Flight Control Team (FCT) operators in NASA s Mission Control Center (MCC) in Houston to transfer an entire or partial computer software configuration item (CSCI) from a flight software compact disk (CD) to the onboard Portable Computer System (PCS). The tool is designed to read the content stored on a flight software CD and generate individual CSCI transfer scripts that are capable of transferring the flight software content in a given subdirectory on the CD to the scratch directory on the PCS. The flight control team can then transfer the flight software from the PCS scratch directory to the Electronically Erasable Programmable Read Only Memory (EEPROM) of an ISS Multiplexer/ Demultiplexer (MDM) via the Indirect File Transfer capability. The individual CSCI scripts and the CSCI Specific Flight Software Image Transfer Script Generator (CFITSG), when executed a second time, will remove all components from their original execution. The tool will identify errors in the transfer process and create logs of the transferred software for the purposes of configuration management.

  18. Conventional MRI and magnetisation transfer imaging of tumour-like multiple sclerosis in a child

    International Nuclear Information System (INIS)

    Metafratzi, Z.; Argyropoulou, M.I.; Efremidis, S.C.; Tzoufi, M.; Papadopoulou, Z.

    2002-01-01

    Tumefactive multiple sclerosis is a rare entity in children. Differential diagnosis includes other mass lesions such as neoplasm and abscess. A case of tumefactive multiple sclerosis in a child is presented. The open-ring pattern of enhancement on conventional MRI and magnetisation transfer imaging was important for the initial diagnosis and the evaluation of the course of the disease. (orig.)

  19. Magnetic resonance imaging of flow and mass transfer in electrohydrodynamic liquid bridges

    NARCIS (Netherlands)

    Wexler, Adam D.; Drusová, Sandra; Fuchs, Elmar C.; Woisetschläger, Jakob; Reiter, Gert; Fuchsjäger, Michael; Reiter, Ursula

    2017-01-01

    Abstract: Here, we report on the feasibility and use of magnetic resonance imaging-based methods to the study of electrohydrodynamic (EHD) liquid bridges. High-speed tomographic recordings through the longitudinal axis of water bridges were used to characterize the mass transfer dynamics, mixing,

  20. Transfer Learning with Convolutional Neural Networks for Classification of Abdominal Ultrasound Images.

    Science.gov (United States)

    Cheng, Phillip M; Malhi, Harshawn S

    2017-04-01

    The purpose of this study is to evaluate transfer learning with deep convolutional neural networks for the classification of abdominal ultrasound images. Grayscale images from 185 consecutive clinical abdominal ultrasound studies were categorized into 11 categories based on the text annotation specified by the technologist for the image. Cropped images were rescaled to 256 × 256 resolution and randomized, with 4094 images from 136 studies constituting the training set, and 1423 images from 49 studies constituting the test set. The fully connected layers of two convolutional neural networks based on CaffeNet and VGGNet, previously trained on the 2012 Large Scale Visual Recognition Challenge data set, were retrained on the training set. Weights in the convolutional layers of each network were frozen to serve as fixed feature extractors. Accuracy on the test set was evaluated for each network. A radiologist experienced in abdominal ultrasound also independently classified the images in the test set into the same 11 categories. The CaffeNet network classified 77.3% of the test set images accurately (1100/1423 images), with a top-2 accuracy of 90.4% (1287/1423 images). The larger VGGNet network classified 77.9% of the test set accurately (1109/1423 images), with a top-2 accuracy of VGGNet was 89.7% (1276/1423 images). The radiologist classified 71.7% of the test set images correctly (1020/1423 images). The differences in classification accuracies between both neural networks and the radiologist were statistically significant (p convolutional neural networks may be used to construct effective classifiers for abdominal ultrasound images.

  1. Imaging and Manipulating Energy Transfer Among Quantum Dots at Individual Dot Resolution.

    Science.gov (United States)

    Nguyen, Duc; Nguyen, Huy A; Lyding, Joseph W; Gruebele, Martin

    2017-06-27

    Many processes of interest in quantum dots involve charge or energy transfer from one dot to another. Energy transfer in films of quantum dots as well as between linked quantum dots has been demonstrated by luminescence shift, and the ultrafast time-dependence of energy transfer processes has been resolved. Bandgap variation among dots (energy disorder) and dot separation are known to play an important role in how energy diffuses. Thus, it would be very useful if energy transfer could be visualized directly on a dot-by-dot basis among small clusters or within films of quantum dots. To that effect, we report single molecule optical absorption detected by scanning tunneling microscopy (SMA-STM) to image energy pooling from donor into acceptor dots on a dot-by-dot basis. We show that we can manipulate groups of quantum dots by pruning away the dominant acceptor dot, and switching the energy transfer path to a different acceptor dot. Our experimental data agrees well with a simple Monte Carlo lattice model of energy transfer, similar to models in the literature, in which excitation energy is transferred preferentially from dots with a larger bandgap to dots with a smaller bandgap.

  2. Plane wave analysis of coherent holographic image reconstruction by phase transfer (CHIRPT).

    Science.gov (United States)

    Field, Jeffrey J; Winters, David G; Bartels, Randy A

    2015-11-01

    Fluorescent imaging plays a critical role in a myriad of scientific endeavors, particularly in the biological sciences. Three-dimensional imaging of fluorescent intensity often requires serial data acquisition, that is, voxel-by-voxel collection of fluorescent light emitted throughout the specimen with a nonimaging single-element detector. While nonimaging fluorescence detection offers some measure of scattering robustness, the rate at which dynamic specimens can be imaged is severely limited. Other fluorescent imaging techniques utilize imaging detection to enhance collection rates. A notable example is light-sheet fluorescence microscopy, also known as selective-plane illumination microscopy, which illuminates a large region within the specimen and collects emitted fluorescent light at an angle either perpendicular or oblique to the illumination light sheet. Unfortunately, scattering of the emitted fluorescent light can cause blurring of the collected images in highly turbid biological media. We recently introduced an imaging technique called coherent holographic image reconstruction by phase transfer (CHIRPT) that combines light-sheet-like illumination with nonimaging fluorescent light detection. By combining the speed of light-sheet illumination with the scattering robustness of nonimaging detection, CHIRPT is poised to have a dramatic impact on biological imaging, particularly for in vivo preparations. Here we present the mathematical formalism for CHIRPT imaging under spatially coherent illumination and present experimental data that verifies the theoretical model.

  3. Perturbation of longitudinal relaxation rate in rotating frame (PLRF) analysis for quantification of chemical exchange saturation transfer signal in a transient state.

    Science.gov (United States)

    Wang, Yi; Zhang, Yaoyu; Zhao, Xuna; Wu, Bing; Gao, Jia-Hong

    2017-11-01

    To develop a novel analytical method for quantification of chemical exchange saturation transfer (CEST) in the transient state. The proposed method aims to reduce the effects of non-chemical-exchange (non-CE) parameters on the CEST signal, emphasizing the effect of chemical exchange. The difference in the longitudinal relaxation rate in the rotating frame ( ΔR1ρ) was calculated based on perturbation of the Z-value by R1ρ, and a saturation-pulse-amplitude-compensated exchange-dependent relaxation rate (SPACER) was determined with a high-exchange-rate approximation. In both phantom and human subject experiments, MTRasym (representative of the traditional CEST index), ΔR1ρ, and SPACER were measured, evaluated, and compared by altering the non-CE parameters in a transient-state continuous-wave CEST sequence. In line with the theoretical expectation, our experimental data demonstrate that the effects of the non-CE parameters can be more effectively reduced using the proposed indices (  ΔR1ρ and SPACER) than using the traditional CEST index ( MTRasym). The proposed method allows for the chemical exchange weight to be better emphasized in the transient-state CEST signal, which is beneficial, in practice, for quantifying the CEST signal. Magn Reson Med 78:1711-1723, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  4. Spin-locking vs. chemical exchange saturation transfer MRI for investigating chemical exchange process between water and labile metabolite protons

    Science.gov (United States)

    Jin, Tao; Autio, Joonas; Obata, Takayuki; Kim, Seong-Gi

    2010-01-01

    Chemical exchange saturation transfer (CEST) and spin-locking (SL) experiments were both able to probe the exchange process between protons of non-equivalent chemical environments. To compare the characteristics of the CEST and SL approaches in the study of chemical exchange effects, we performed CEST and SL experiments at varied pH and concentrated metabolites with exchangeable amide, amine, and hydroxyl protons at 9.4 T. Our results show that: i) On-resonance SL is most sensitive to chemical exchanges in the intermediate exchange regime and is able to detect hydroxyl and amine protons on a millimolar concentration scale. Off-resonance SL and CEST approaches are sensitive to slow-exchanging protons when an optimal SL or saturation pulse power matches the exchanging rate, respectively. ii) Offset frequency-dependent SL and CEST spectra are very similar, and can be explained well with an SL model recently developed by Trott and Palmer. iii) The exchange rate and population of metabolite protons can be determined from offset-dependent SL or CEST spectra or from on-resonance SL relaxation dispersion measurements. iv) The asymmetry of the magnetization transfer ratio (MTRasym) is highly dependent on the choice of saturation pulse power. In the intermediate exchange regime, MTRasym becomes complicated and should be interpreted with care. PMID:21500270

  5. Spin-locking versus chemical exchange saturation transfer MRI for investigating chemical exchange process between water and labile metabolite protons.

    Science.gov (United States)

    Jin, Tao; Autio, Joonas; Obata, Takayuki; Kim, Seong-Gi

    2011-05-01

    Chemical exchange saturation transfer (CEST) and spin-locking (SL) experiments were both able to probe the exchange process between protons of nonequivalent chemical environments. To compare the characteristics of the CEST and SL approaches in the study of chemical exchange effects, we performed CEST and SL experiments at varied pH and concentrated metabolite phantoms with exchangeable amide, amine, and hydroxyl protons at 9.4 T. Our results show that: (i) on-resonance SL is most sensitive to chemical exchanges in the intermediate-exchange regime and is able to detect hydroxyl and amine protons on a millimolar concentration scale. Off-resonance SL and CEST approaches are sensitive to slow-exchanging protons when an optimal SL or saturation pulse power matches the exchanging rate, respectively. (ii) Offset frequency-dependent SL and CEST spectra are very similar and can be explained well with an SL model recently developed by Trott and Palmer (J Magn Reson 2002;154:157-160). (iii) The exchange rate and population of metabolite protons can be determined from offset-dependent SL or CEST spectra or from on-resonance SL relaxation dispersion measurements. (iv) The asymmetry of the magnetization transfer ratio (MTR(asym)) is highly dependent on the choice of saturation pulse power. In the intermediate-exchange regime, MTR(asym) becomes complicated and should be interpreted with care. Copyright © 2010 Wiley-Liss, Inc.

  6. Process techniques of charge transfer time reduction for high speed CMOS image sensors

    International Nuclear Information System (INIS)

    Cao Zhongxiang; Li Quanliang; Han Ye; Qin Qi; Feng Peng; Liu Liyuan; Wu Nanjian

    2014-01-01

    This paper proposes pixel process techniques to reduce the charge transfer time in high speed CMOS image sensors. These techniques increase the lateral conductivity of the photo-generated carriers in a pinned photodiode (PPD) and the voltage difference between the PPD and the floating diffusion (FD) node by controlling and optimizing the N doping concentration in the PPD and the threshold voltage of the reset transistor, respectively. The techniques shorten the charge transfer time from the PPD diode to the FD node effectively. The proposed process techniques do not need extra masks and do not cause harm to the fill factor. A sub array of 32 × 64 pixels was designed and implemented in the 0.18 μm CIS process with five implantation conditions splitting the N region in the PPD. The simulation and measured results demonstrate that the charge transfer time can be decreased by using the proposed techniques. Comparing the charge transfer time of the pixel with the different implantation conditions of the N region, the charge transfer time of 0.32 μs is achieved and 31% of image lag was reduced by using the proposed process techniques. (semiconductor devices)

  7. Use of a laser-induced fluorescence thermal imaging system for film cooling heat transfer measurement

    Energy Technology Data Exchange (ETDEWEB)

    Chyu, M.K. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    1995-10-01

    This paper describes a novel approach based on fluorescence imaging of thermographic phosphor that enables the simultaneous determination of both local film effectiveness and local heat transfer on a film-cooled surface. The film cooling model demonstrated consists of a single row of three discrete holes on a flat plate. The transient temperature measurement relies on the temperature-sensitive fluorescent properties of europium-doped lanthanum oxysulfide (La{sub 2}O{sub 2}S:EU{sup 3+}) thermographic phosphor. A series of full-field surface temperatures, mainstream temperatures, and coolant film temperatures were acquired during the heating of a test surface. These temperatures are used to calculate the heat transfer coefficients and the film effectiveness simultaneously. Because of the superior spatial resolution capability for the heat transfer data reduced from these temperature frames, the laser-induced fluorescence (LIF) imaging system, the present study observes the detailed heat transfer characteristics over a film-protected surface. The trend of the results agrees with those obtained using other conventional thermal methods, as well as the liquid crystal imaging technique. One major advantage of this technique is the capability to record a large number of temperature frames over a given testing period. This offers multiple-sample consistency.

  8. One Size Fits All: Evaluation of the Transferability of a New "Learning" Histologic Image Analysis Application.

    Science.gov (United States)

    Arlt, Janine; Homeyer, André; Sänger, Constanze; Dahmen, Uta; Dirsch, Olaf

    2016-01-01

    Quantitative analysis of histologic slides is of importance for pathology and also to address surgical questions. Recently, a novel application was developed for the automated quantification of whole-slide images. The aim of this study was to test and validate the underlying image analysis algorithm with respect to user friendliness, accuracy, and transferability to different histologic scenarios. The algorithm splits the images into tiles of a predetermined size and identifies the tissue class of each tile. In the training procedure, the user specifies example tiles of the different tissue classes. In the subsequent analysis procedure, the algorithm classifies each tile into the previously specified classes. User friendliness was evaluated by recording training time and testing reproducibility of the training procedure of users with different background. Accuracy was determined with respect to single and batch analysis. Transferability was demonstrated by analyzing tissue of different organs (rat liver, kidney, small bowel, and spleen) and with different stainings (glutamine synthetase and hematoxylin-eosin). Users of different educational background could apply the program efficiently after a short introduction. When analyzing images with similar properties, accuracy of >90% was reached in single images as well as in batch mode. We demonstrated that the novel application is user friendly and very accurate. With the "training" procedure the application can be adapted to novel image characteristics simply by giving examples of relevant tissue structures. Therefore, it is suitable for the fast and efficient analysis of high numbers of fully digitalized histologic sections, potentially allowing "high-throughput" quantitative "histomic" analysis.

  9. Amide proton transfer imaging for differentiation of benign and atypical meningiomas

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Bio [The Armed Forces Capital Hospital, Department of Radiology, Seongnam, Gyeonggi-do (Korea, Republic of); Han, Kyunghwa; Choi, Yoon Seong; Lee, Seung-Koo [Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, College of Medicine, Seoul (Korea, Republic of); Ahn, Sung Soo [Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, College of Medicine, Seoul (Korea, Republic of); Yonsei University, Department of Radiology, College of Medicine, Seoul (Korea, Republic of); Chang, Jong Hee; Kang, Seok-Gu [Yonsei University College of Medicine, Department of Neurosurgery, Seoul (Korea, Republic of); Kim, Se Hoon [Yonsei University College of Medicine, Department of Pathology, Seoul (Korea, Republic of); Zhou, Jinyuan [Johns Hopkins University School of Medicine, Division of MRI Research, Department of Radiology, Baltimore, MD (United States)

    2018-01-15

    To investigate the difference in amide proton transfer (APT)-weighted signals between benign and atypical meningiomas and determine the value of APT imaging for differentiating the two. Fifty-seven patients with pathologically diagnosed meningiomas (benign, 44; atypical, 13), who underwent preoperative MRI with APT imaging between December 2014 and August 2016 were included. We compared normalised magnetisation transfer ratio asymmetry (nMTR{sub asym}) values between benign and atypical meningiomas on APT-weighted images. Conventional MRI features were qualitatively assessed. Both imaging features were evaluated by multivariable logistic regression analysis. The discriminative value of MRI with and without nMTR{sub asym} was evaluated. The nMTR{sub asym} of atypical meningiomas was significantly greater than that of benign meningiomas (2.46% vs. 1.67%; P < 0.001). In conventional MR images, benign and atypical meningiomas exhibited significant differences in maximum tumour diameter, non-skull base location, and heterogeneous enhancement. On multivariable logistic regression analysis, high nMTR{sub asym} was an independent predictor of atypical meningiomas (adjusted OR, 11.227; P = 0.014). The diagnostic performance of MRI improved with nMTR{sub asym} for predicting atypical meningiomas. Atypical meningiomas exhibited significantly higher APT-weighted signal intensities than benign meningiomas. The discriminative value of conventional MRI improved significantly when combined with APT imaging for diagnosis of atypical meningioma. (orig.)

  10. Geodesic Flow Kernel Support Vector Machine for Hyperspectral Image Classification by Unsupervised Subspace Feature Transfer

    Directory of Open Access Journals (Sweden)

    Alim Samat

    2016-03-01

    Full Text Available In order to deal with scenarios where the training data, used to deduce a model, and the validation data have different statistical distributions, we study the problem of transformed subspace feature transfer for domain adaptation (DA in the context of hyperspectral image classification via a geodesic Gaussian flow kernel based support vector machine (GFKSVM. To show the superior performance of the proposed approach, conventional support vector machines (SVMs and state-of-the-art DA algorithms, including information-theoretical learning of discriminative cluster for domain adaptation (ITLDC, joint distribution adaptation (JDA, and joint transfer matching (JTM, are also considered. Additionally, unsupervised linear and nonlinear subspace feature transfer techniques including principal component analysis (PCA, randomized nonlinear principal component analysis (rPCA, factor analysis (FA and non-negative matrix factorization (NNMF are investigated and compared. Experiments on two real hyperspectral images show the cross-image classification performances of the GFKSVM, confirming its effectiveness and suitability when applied to hyperspectral images.

  11. Postcontrast T1-weighted brain magnetic resonance imaging in pediatric patients: comparison between postcontrast fat-suppression imaging and conventional T1-weighted or magnetization transfer imaging

    International Nuclear Information System (INIS)

    Lee, Choong Wook; Goo, Hyun Woo

    2004-01-01

    We wished to assess the merits and weaknesses of postcontrast fat-suppression (FS) brain MR imaging in children for the evaluation of various enhancing lesions as compared with postcontrast conventional T1-weighted or magnetization transfer (MT) imaging. We reviewed the records of those patients with enhancing lesions on brain MR imaging who had undergone both FS imaging and one of the conventional T1-weighted or MT imaging as a post-contrast T1-weighted brain MR imaging. Thirty-one patients (21 male, 10 female; mean age, 8.7 years) with 38 enhancing lesions (18 intra-axial, 16 extra-axial and 4 orbital locations) were included in this study. There were 27 pairs of FS and conventional imagings, and 13 pairs of FS and MT imagings available for evaluation. Two radiologists visually assessed by consensus the lesions' conspicuity, and they also looked for the presence of flow or susceptibility artifacts in a total of 40 pairs of MR imagings. For 19 measurable lesions (14 pairs of FS and conventional T1-weighted imagings, 5 pairs of FS and MT imagings), the contrast ratios between the lesion and the normal brain ([SIlesion-SIwater]/[SInormal brain-SIwater]) were calculated and compared. Compared with conventional imaging, the lesion conspicuity on FS imaging was better in 10 cases (7 extra-axial lesions, 2 orbital lesions and 1 fat-containing intra-axial lesion), equal in 16 cases, and worse in one case. Compared with MT imaging, the lesion conspicuity on FS imaging was better in 3 cases (2 extra-axial lesions and 1 intra-axial lesion), equal in 8 cases, and worse in 2 cases. Image quality of FS imaging was compromised by flow or susceptibility artifacts for 7 patients. The contrast ratios for FS imaging were not significantly different from those for conventional imaging (2.2±0.7 vs. 2.2±0.6, respectively, p=0.914) and they were significantly lower than those for MT imaging (2.4±0.8 vs. 4.5±1.5, respectively, p=0.018). Postcontrast FS brain MR imaging appears to be

  12. TRANSFER

    African Journals Online (AJOL)

    This paper reports on further studies on long range energy transfer between curcumine as donor and another thiazine dye, thionine, which is closely related to methylene blue as energy harvester (Figure 1). Since thionine is known to have a higher quantum yield of singlet oxygen sensitization than methylene blue [8], it is ...

  13. Imaging and modeling of collagen architecture in living tissue with polarized light transfer (Conference Presentation)

    Science.gov (United States)

    Ramella-Roman, Jessica C.; Stoff, Susan; Chue-Sang, Joseph; Bai, Yuqiang

    2016-03-01

    The extra-cellular space in connective tissue of animals and humans alike is comprised in large part of collagen. Monitoring of collagen arrangement and cross-linking has been utilized to diagnose a variety of medical conditions and guide surgical intervention. For example, collagen monitoring is useful in the assessment and treatment of cervical cancer, skin cancer, myocardial infarction, and non-arteritic anterior ischemic optic neuropathy. We have developed a suite of tools and models based on polarized light transfer for the assessment of collagen presence, cross-linking, and orientation in living tissue. Here we will present some example of such approach applied to the human cervix. We will illustrate a novel Mueller Matrix (MM) imaging system for the study of cervical tissue; furthermore we will show how our model of polarized light transfer through cervical tissue compares to the experimental findings. Finally we will show validation of the methodology through histological results and Second Harmonic imaging microscopy.

  14. Interactive definition of transfer functions in volume rendering based on image markers

    International Nuclear Information System (INIS)

    Teistler, Michael; Nowinski, Wieslaw L.; Breiman, Richard S.; Liong, Sauw Ming; Ho, Liang Yoong; Shahab, Atif

    2007-01-01

    Objectives A user interface for transfer function (TF) definition in volume rendering (VR) was developed that allows the user to intuitively assign color and opacity to the original image intensities. This software may surpass solutions currently deployed in clinical practice by simplifying the use of TFs beyond predefined settings that are not always applicable. Materials and methods The TF definition is usually a cumbersome task that requires the user to manipulate graphical representations of the TF (e.g. trapezoids). A new method that allows the user to place markers at points of interest directly on CT and MRI images or orthogonal reformations was developed based on two-dimensional region growing and a few user-definable marker-related parameters. For each user defined image marker, a segment of the transfer function is computed. The resulting TF can also be applied to the slice image views. Results were judged subjectively. Results Each individualized TF can be defined interactively in a few simple steps. For every user interaction, immediate visual feedback is given. Clinicians who tested the application appreciated being able to directly work on familiar slice images to generate the desired 3D views. Conclusion Interactive TF definition can increase the actual utility of VR, help to understand the role of the TF with its variations, and increase the acceptance of VR as a clinical tool. (orig.)

  15. Retrieval of spruce leaf chlorophyll content from airborne image data using continuum removal and radiative transfer

    Czech Academy of Sciences Publication Activity Database

    Malenovský, Z.; Homolová, L.; Zurita-Milla, R.; Lukeš, Petr; Kaplan, Věroslav; Hanuš, Jan; Gastellu-Etchegory, J.P.; Schaepman, M.E.

    2013-01-01

    Roč. 131, APR (2013), s. 85-102 ISSN 0034-4257 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk(CZ) LM2010007 Institutional support: RVO:67179843 Keywords : Chlorophyll retrieval * Imaging spectroscopy * Continuum removal * Radiative transfer * PROSPECT * DART * Optical indices * Norway spruce * High spatial resolution * AISA Subject RIV: EH - Ecology, Behaviour Impact factor: 4.769, year: 2013

  16. The Physics of Imaging with Remote Sensors : Photon State Space & Radiative Transfer

    Science.gov (United States)

    Davis, Anthony B.

    2012-01-01

    Standard (mono-pixel/steady-source) retrieval methodology is reaching its fundamental limit with access to multi-angle/multi-spectral photo- polarimetry. Next... Two emerging new classes of retrieval algorithm worth nurturing: multi-pixel time-domain Wave-radiometry transition regimes, and more... Cross-fertilization with bio-medical imaging. Physics-based remote sensing: - What is "photon state space?" - What is "radiative transfer?" - Is "the end" in sight? Two wide-open frontiers! center dot Examples (with variations.

  17. Initial study of magnetization transfer contrast MR imaging of the knee at 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Yoshioka, Hiroshi; Echigo, Junko; Niitsu, Mamoru; Anno, Izumi; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Nakai, Toshiharu; Sato, Hiroshi; Tsukamoto, Tetsuji

    1998-10-01

    It has been reported that various image sequences, including magnetization transfer contrast (MTC) were effective in evaluating articular cartilage. It is difficult to identify cartilaginous structures, however, using conventional MR imaging because of low spatial resolution and low signal-to-noise (S/N) ratio. The purpose of the present study was to evaluate the optimal imaging sequences with MTC pulse at 3 T and to assess the feasibility of the clinical application thereof. Five porcine knees were studied using varying imaging parameters (frequency offset, flip angle (FA) and echo time (TE)) combined with off-resonance sinc radiation pulses. The effect of MTC was analyzed by dividing the signal intensity of MTC GRE images by that of conventional GRE images (Ms/Mo). MTC images were obtained with a low specific absorption rate (SAR). With an offset frequency of 1.5 kHz (repetition time/TE/FA=60 ms/8 ms/30 degrees), the mean Ms/Mo of articular cartilage and meniscus was 0.70 and 0.65, respectively. An FA of 20 to 30 degrees and a TE of 11 to 12 ms appear to be optimal parameters at 3 T with MTC pulse because of the higher S/N ratio of cartilage and higher contrast-to-noise ratio of cartilage relative to that of distilled water. These findings suggest that MTC at 3 T may be feasible and effective for assessment of cartilage and meniscus in clinical applications. (author)

  18. Image Processing for Bioluminescence Resonance Energy Transfer Measurement—BRET-Analyzer

    Directory of Open Access Journals (Sweden)

    Yan Chastagnier

    2018-01-01

    Full Text Available A growing number of tools now allow live recordings of various signaling pathways and protein-protein interaction dynamics in time and space by ratiometric measurements, such as Bioluminescence Resonance Energy Transfer (BRET Imaging. Accurate and reproducible analysis of ratiometric measurements has thus become mandatory to interpret quantitative imaging. In order to fulfill this necessity, we have developed an open source toolset for Fiji—BRET-Analyzer—allowing a systematic analysis, from image processing to ratio quantification. We share this open source solution and a step-by-step tutorial at https://github.com/ychastagnier/BRET-Analyzer. This toolset proposes (1 image background subtraction, (2 image alignment over time, (3 a composite thresholding method of the image used as the denominator of the ratio to refine the precise limits of the sample, (4 pixel by pixel division of the images and efficient distribution of the ratio intensity on a pseudocolor scale, and (5 quantification of the ratio mean intensity and standard variation among pixels in chosen areas. In addition to systematize the analysis process, we show that the BRET-Analyzer allows proper reconstitution and quantification of the ratiometric image in time and space, even from heterogeneous subcellular volumes. Indeed, analyzing twice the same images, we demonstrate that compared to standard analysis BRET-Analyzer precisely define the luminescent specimen limits, enlightening proficient strengths from small and big ensembles over time. For example, we followed and quantified, in live, scaffold proteins interaction dynamics in neuronal sub-cellular compartments including dendritic spines, for half an hour. In conclusion, BRET-Analyzer provides a complete, versatile and efficient toolset for automated reproducible and meaningful image ratio analysis.

  19. Information Recovery Algorithm for Ground Objects in Thin Cloud Images by Fusing Guide Filter and Transfer Learning

    Directory of Open Access Journals (Sweden)

    HU Gensheng

    2018-03-01

    Full Text Available Ground object information of remote sensing images covered with thin clouds is obscure. An information recovery algorithm for ground objects in thin cloud images is proposed by fusing guide filter and transfer learning. Firstly, multi-resolution decomposition of thin cloud target images and cloud-free guidance images is performed by using multi-directional nonsubsampled dual-tree complex wavelet transform. Then the decomposed low frequency subbands are processed by using support vector guided filter and transfer learning respectively. The decomposed high frequency subbands are enhanced by using modified Laine enhancement function. The low frequency subbands output by guided filter and those predicted by transfer learning model are fused by the method of selection and weighting based on regional energy. Finally, the enhanced high frequency subbands and the fused low frequency subbands are reconstructed by using inverse multi-directional nonsubsampled dual-tree complex wavelet transform to obtain the ground object information recovery images. Experimental results of Landsat-8 OLI multispectral images show that, support vector guided filter can effectively preserve the detail information of the target images, domain adaptive transfer learning can effectively extend the range of available multi-source and multi-temporal remote sensing images, and good effects for ground object information recover are obtained by fusing guide filter and transfer learning to remove thin cloud on the remote sensing images.

  20. Transferring biomarker into molecular probe: melanin nanoparticle as a naturally active platform for multimodality imaging.

    Science.gov (United States)

    Fan, Quli; Cheng, Kai; Hu, Xiang; Ma, Xiaowei; Zhang, Ruiping; Yang, Min; Lu, Xiaomei; Xing, Lei; Huang, Wei; Gambhir, Sanjiv Sam; Cheng, Zhen

    2014-10-29

    Developing multifunctional and easily prepared nanoplatforms with integrated different modalities is highly challenging for molecular imaging. Here, we report the successful transfer of an important molecular target, melanin, into a novel multimodality imaging nanoplatform. Melanin is abundantly expressed in melanotic melanomas and thus has been actively studied as a target for melanoma imaging. In our work, the multifunctional biopolymer nanoplatform based on ultrasmall (passive nanoplatforms require complicated and time-consuming processes for prebuilding reporting moieties or chemical modifications using active groups to integrate different contrast properties into one entity. In comparison, utilizing functional biomarker melanin can greatly simplify the building process. We further conjugated αvβ3 integrins, cyclic c(RGDfC) peptide, to MNPs to allow for U87MG tumor accumulation due to its targeting property combined with the enhanced permeability and retention (EPR) effect. The multimodal properties of MNPs demonstrate the high potential of endogenous materials with multifunctions as nanoplatforms for molecular theranostics and clinical translation.

  1. Spherical gradient-index lenses as perfect imaging and maximum power transfer devices.

    Science.gov (United States)

    Gordon, J M

    2000-08-01

    Gradient-index lenses can be viewed from the perspectives of both imaging and nonimaging optics, that is, in terms of both image fidelity and achievable flux concentration. The simple class of gradient-index lenses with spherical symmetry, often referred to as modified Luneburg lenses, is revisited. An alternative derivation for established solutions is offered; the method of Fermat's strings and the principle of skewness conservation are invoked. Then these nominally perfect imaging devices are examined from the additional vantage point of power transfer, and the degree to which they realize the thermodynamic limit to flux concentration is determined. Finally, the spherical gradient-index lens of the fish eye is considered as a modified Luneburg lens optimized subject to material constraints.

  2. Seven-Tesla Magnetization Transfer Imaging to Detect Multiple Sclerosis White Matter Lesions.

    Science.gov (United States)

    Chou, I-Jun; Lim, Su-Yin; Tanasescu, Radu; Al-Radaideh, Ali; Mougin, Olivier E; Tench, Christopher R; Whitehouse, William P; Gowland, Penny A; Constantinescu, Cris S

    2018-03-01

    Fluid-attenuated inversion recovery (FLAIR) imaging at 3 Tesla (T) field strength is the most sensitive modality for detecting white matter lesions in multiple sclerosis. While 7T FLAIR is effective in detecting cortical lesions, it has not been fully optimized for visualization of white matter lesions and thus has not been used for delineating lesions in quantitative magnetic resonance imaging (MRI) studies of the normal appearing white matter in multiple sclerosis. Therefore, we aimed to evaluate the sensitivity of 7T magnetization-transfer-weighted (MT w ) images in the detection of white matter lesions compared with 3T-FLAIR. Fifteen patients with clinically isolated syndrome, 6 with multiple sclerosis, and 10 healthy participants were scanned with 7T 3-dimensional (D) MT w and 3T-2D-FLAIR sequences on the same day. White matter lesions visible on either sequence were delineated. Of 662 lesions identified on 3T-2D-FLAIR images, 652 were detected on 7T-3D-MT w images (sensitivity, 98%; 95% confidence interval, 97% to 99%). The Spearman correlation coefficient between lesion loads estimated by the two sequences was .910. The intrarater and interrater reliability for 7T-3D-MT w images was good with an intraclass correlation coefficient (ICC) of 98.4% and 81.8%, which is similar to that for 3T-2D-FLAIR images (ICC 96.1% and 96.7%). Seven-Tesla MT w sequences detected most of the white matter lesions identified by FLAIR at 3T. This suggests that 7T-MT w imaging is a robust alternative for detecting demyelinating lesions in addition to 3T-FLAIR. Future studies need to compare the roles of optimized 7T-FLAIR and of 7T-MT w imaging. © 2017 The Authors. Journal of Neuroimaging published by Wiley Periodicals, Inc. on behalf of American Society of Neuroimaging.

  3. Short-Term Solar Irradiance Forecasts Using Sky Images and Radiative Transfer Model

    Directory of Open Access Journals (Sweden)

    Juan Du

    2018-05-01

    Full Text Available In this paper, we propose a novel forecast method which addresses the difficulty in short-term solar irradiance forecasting that arises due to rapidly evolving environmental factors over short time periods. This involves the forecasting of Global Horizontal Irradiance (GHI that combines prediction sky images with a Radiative Transfer Model (RTM. The prediction images (up to 10 min ahead are produced by a non-local optical flow method, which is used to calculate the cloud motion for each pixel, with consecutive sky images at 1 min intervals. The Direct Normal Irradiance (DNI and the diffuse radiation intensity field under clear sky and overcast conditions obtained from the RTM are then mapped to the sky images. Through combining the cloud locations on the prediction image with the corresponding instance of image-based DNI and diffuse radiation intensity fields, the GHI can be quantitatively forecasted for time horizons of 1–10 min ahead. The solar forecasts are evaluated in terms of root mean square error (RMSE and mean absolute error (MAE in relation to in-situ measurements and compared to the performance of the persistence model. The results of our experiment show that GHI forecasts using the proposed method perform better than the persistence model.

  4. Conception and data transfer analysis of an open-source digital image archive designed for radiology

    International Nuclear Information System (INIS)

    Teichgraeber, U.K.M.; Lehmkuhl, L.; Harderer, A.; Emmel, D.; Ehrenstein, T.; Ricke, J.; Felix, R.

    2003-01-01

    Purpose: Implementation of a self-designed, web-based digital image archive incorporating the existing DICOM infrastructure to assure distribution of digital pictures and reports and to optimize work flow. Assessment after three years. Materials and methods: Open-source software was used to guarantee highest reliability and cost effectiveness. In view of rapidly increasing capacity and decreasing costs of hard discs (HDs), HDs were preferred over slower and expensive magneto-optical disk (MOD) or tape storage systems. The number of installed servers increased from one to 12. By installing HDs with increased capacities, the number of servers should be kept constant. Entry and access of data were analyzed over two 4-month periods (after 1.5 and 2 years of continuous operations). Results: Our digital image archive was found to be very reliable, cost effective and suitable for its designated tasks. As judged from the measured access volume, the average utilization of the system increased by 160%. In the period from January to April 2002, the users accessed 239.8 gigabyte of the stored 873.7 gigabyte image data (27%). The volume of the stored data added 20%, mainly due to an increase in cross-section imaging. Conclusion: The challenge of developing a digital image archive with limited financial resources resulted in a practicable and expandable solution. The utilization, number of active users and volume of transferred data have increased significantly. Our concept of utilizing HDs for image storage proved to be successful. (orig.) [de

  5. Amide proton transfer imaging in clinics: Basic concepts and current and future use in brain tumors and stoke

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ji Eun [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Jahng, Geon Ho [Dept. of Radiology, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Jeong, Ha Kyu [Philips Korea, Seoul (Korea, Republic of)

    2016-12-15

    Amide proton transfer (APT) imaging is gaining attention as a relatively new in vivo molecular imaging technique that has higher sensitivity and spatial resolution than magnetic resonance spectroscopy imaging. APT imaging is a subset of the chemical exchange saturation transfer mechanism, which can offer unique image contrast by selectively saturating protons in target molecules that get exchanged with protons in bulk water. In this review, we describe the basic concepts of APT imaging, particularly with regard to the benefit in clinics from the current literature. Clinical applications of APT imaging are described from two perspectives: in the diagnosis and monitoring of the treatment response in brain glioma by reflecting endogenous mobile proteins and peptides, and in the potential for stroke imaging with respect to tissue acidity.

  6. Ultra-portable field transfer radiometer for vicarious calibration of earth imaging sensors

    Science.gov (United States)

    Thome, Kurtis; Wenny, Brian; Anderson, Nikolaus; McCorkel, Joel; Czapla-Myers, Jeffrey; Biggar, Stuart

    2018-06-01

    A small portable transfer radiometer has been developed as part of an effort to ensure the quality of upwelling radiance from test sites used for vicarious calibration in the solar reflective. The test sites are used to predict top-of-atmosphere reflectance relying on ground-based measurements of the atmosphere and surface. The portable transfer radiometer is designed for one-person operation for on-site field calibration of instrumentation used to determine ground-leaving radiance. The current work describes the detector- and source-based radiometric calibration of the transfer radiometer highlighting the expected accuracy and SI-traceability. The results indicate differences between the detector-based and source-based results greater than the combined uncertainties of the approaches. Results from recent field deployments of the transfer radiometer using a solar radiation based calibration agree with the source-based laboratory calibration within the combined uncertainties of the methods. The detector-based results show a significant difference to the solar-based calibration. The source-based calibration is used as the basis for a radiance-based calibration of the Landsat-8 Operational Land Imager that agrees with the OLI calibration to within the uncertainties of the methods.

  7. PET/CT (and CT) instrumentation, image reconstruction and data transfer for radiotherapy planning

    International Nuclear Information System (INIS)

    Sattler, Bernhard; Lee, John A.; Lonsdale, Markus; Coche, Emmanuel

    2010-01-01

    computed tomography (CT) are used to communicate the actual image data created by the modalities. Care must be taken for data security, especially when transferring data across the (network-) borders of different hospitals. Overall, the most important precondition for successful integration of functional imaging in RT treatment planning is the goal orientated as well as close and thorough communication between nuclear medicine and radiotherapy departments on all levels of interaction (personnel, imaging protocols, GTV delineation, and selection of the data transfer method).

  8. Characterization of orthogonal transfer array CCDs for the WIYN one degree imager

    Science.gov (United States)

    Lesser, Michael; Ouellette, David; Boroson, Todd; Harbeck, Daniel; Martin, Pierre; Jacoby, George; Cavin, John; Sawyer, David; Boggs, Kasey; Bredthauer, Richard

    2012-03-01

    The WIYN One Degree Imager (ODI) will provide a one degree field of view for the WIYN 3.5 m telescope located on Kitt Peak near Tucson, Arizona. Its focal plane consists of an 8x8 grid of Orthogonal Transfer Array (OTA) CCD detectors. These detectors are the STA2200 OTA CCDs designed and fabricated by Semiconductor Technology Associates, Inc. and backside processed at the University of Arizona Imaging Technology Laboratory. Several lot runs of the STA2200 detectors have been fabricated. We have backside processed devices from these different lots and provide detector performance characterization, including noise, CTE, cosmetics, quantum efficiency, and some orthogonal transfer characteristics. We discuss the performance differences for the devices with different silicon thickness and resistivity. A fully buttable custom detector package has been developed for this project which allows hybridization of the silicon detectors directly onto an aluminum nitride substrate with an embedded pin grid array. This package is mounted on a silicon-aluminum alloy which provides a flat imaging surface of less than 20 microns peakvalley at the -100 C operating temperature. Characterization of the package performance, including low temperature profilometry, is described in this paper.

  9. Magnetization transfer and spin lock MR imaging of patellar cartilage degeneration at 0.1 T

    International Nuclear Information System (INIS)

    Koskinen, S.K.; Ylae-Outinen, H.; Komu, M.E.S.; Aho, H.J.

    1997-01-01

    Purpose: To investigate magnetization transfer (MT) parameters and rotating frame relaxation time T1ρ in patellar cartilage at different levels of degeneration. Material and Methods: Thirty cadaveric patellae were examined at 0.1 T using the time-dependent saturation-transfer MT technique and the spin lock (SL) technique. In an SL experiment, nuclear spins are locked with a radiofrequency (RF) field, and the locked nuclear magnetization relaxes along the magnetic component of the locking RF field. The specimens were divided into three groups according to the level of cartilage degeneration. MT parameters and T1ρ were measured. Results: The MT effect was greater in degenerated cartilage than in normal cartilage. T1ρ was longer in advanced cartilage degeneration than in intermediate cartilage degeneration. Conculsion: The results suggest that more studies are needed to fully establish the value of SL imaging in cartilage degeneration. (orig.)

  10. Measurement of the presampled two-dimensional modulation transfer function of digital imaging systems

    International Nuclear Information System (INIS)

    Fetterly, Kenneth A.; Hangiandreou, Nicholas J.; Schueler, Beth A.; Ritenour, E. Russell

    2002-01-01

    The purpose of this work was to develop methods to measure the presampled two-dimensional modulation transfer function (2D MTF) of digital imaging systems. A custom x-ray 'point source' phantom was created by machining 256 holes with diameter 0.107 mm through a 0.5-mm-thick copper plate. The phantom was imaged several times, resulting in many images of individual x-ray 'spots'. The center of each spot (with respect to the pixel matrix) was determined to subpixel accuracy by fitting each spot to a 2D Gaussian function. The subpixel spot center locations were used to create a 5x oversampled system point spread function (PSF), which characterizes the optical and electrical properties of the system and is independent of the pixel sampling of the original image. The modulus of the Fourier transform of the PSF was calculated. Next, the Fourier function was normalized to the zero frequency value. Finally, the Fourier transform function was divided by the first-order Bessel function that defined the frequency content of the holes, resulting in the presampled 2D MTF. The presampled 2D MTF of a 0.1 mm pixel pitch computed radiography system and 0.2 mm pixel pitch flat panel digital imaging system that utilized a cesium iodide scintillator was measured. Comparison of the axial components of the 2D MTF to one-dimensional MTF measurements acquired using an edge device method demonstrated that the two methods produced consistent results

  11. End-to-End Airplane Detection Using Transfer Learning in Remote Sensing Images

    Directory of Open Access Journals (Sweden)

    Zhong Chen

    2018-01-01

    Full Text Available Airplane detection in remote sensing images remains a challenging problem due to the complexity of backgrounds. In recent years, with the development of deep learning, object detection has also obtained great breakthroughs. For object detection tasks in natural images, such as the PASCAL (Pattern Analysis, Statistical Modelling and Computational Learning VOC (Visual Object Classes Challenge, the major trend of current development is to use a large amount of labeled classification data to pre-train the deep neural network as a base network, and then use a small amount of annotated detection data to fine-tune the network for detection. In this paper, we use object detection technology based on deep learning for airplane detection in remote sensing images. In addition to using some characteristics of remote sensing images, some new data augmentation techniques have been proposed. We also use transfer learning and adopt a single deep convolutional neural network and limited training samples to implement end-to-end trainable airplane detection. Classification and positioning are no longer divided into multistage tasks; end-to-end detection attempts to combine them for optimization, which ensures an optimal solution for the final stage. In our experiment, we use remote sensing images of airports collected from Google Earth. The experimental results show that the proposed algorithm is highly accurate and meaningful for remote sensing object detection.

  12. The effects of image transfer strategy achieved through cobranding and brand extension

    Directory of Open Access Journals (Sweden)

    Rakita Branko

    2010-01-01

    Full Text Available This paper investigates the strategic importance of brand extension and cobranding. These two strategies we identify as the most important and the most popular brand image transfer strategies. They are widely adopted strategies for firms entering new markets, so they can take advantage of an existing brand's equity. In this article, we investigate whether cobranding with partner and brand extension has positive effects on customers' responses toward a new product. We also analyzed prerequisites for successful implementation of mentioned brand strategies. .

  13. A Novel Image Encryption Scheme Based on Clifford Attractor and Noisy Logistic Map for Secure Transferring Images in Navy

    Directory of Open Access Journals (Sweden)

    Mohadeseh Kanafchian

    2017-04-01

    In this paper, we first give a brief introduction into chaotic image encryption and then we investigate some important properties and behaviour of the logistic map. The logistic map, aperiodic trajectory, or random-like fluctuation, could not be obtained with some choice of initial condition. Therefore, a noisy logistic map with an additive system noise is introduced. The proposed scheme is based on the extended map of the Clifford strange attractor, where each dimension has a specific role in the encryption process. Two dimensions are used for pixel permutation and the third dimension is used for pixel diffusion. In order to optimize the Clifford encryption system we increase the space key by using the noisy logistic map and a novel encryption scheme based on the Clifford attractor and the noisy logistic map for secure transfer images is proposed. This algorithm consists of two parts: the noisy logistic map shuffle of the pixel position and the pixel value. We use times for shuffling the pixel position and value then we generate the new pixel position and value by the Clifford system. To illustrate the efficiency of the proposed scheme, various types of security analysis are tested. It can be concluded that the proposed image encryption system is a suitable choice for practical applications.

  14. [A Method to Reconstruct Surface Reflectance Spectrum from Multispectral Image Based on Canopy Radiation Transfer Model].

    Science.gov (United States)

    Zhao, Yong-guang; Ma, Ling-ling; Li, Chuan-rong; Zhu, Xiao-hua; Tang, Ling-li

    2015-07-01

    Due to the lack of enough spectral bands for multi-spectral sensor, it is difficult to reconstruct surface retlectance spectrum from finite spectral information acquired by multi-spectral instrument. Here, taking into full account of the heterogeneity of pixel from remote sensing image, a method is proposed to simulate hyperspectral data from multispectral data based on canopy radiation transfer model. This method first assumes the mixed pixels contain two types of land cover, i.e., vegetation and soil. The sensitive parameters of Soil-Leaf-Canopy (SLC) model and a soil ratio factor were retrieved from multi-spectral data based on Look-Up Table (LUT) technology. Then, by combined with a soil ratio factor, all the parameters were input into the SLC model to simulate the surface reflectance spectrum from 400 to 2 400 nm. Taking Landsat Enhanced Thematic Mapper Plus (ETM+) image as reference image, the surface reflectance spectrum was simulated. The simulated reflectance spectrum revealed different feature information of different surface types. To test the performance of this method, the simulated reflectance spectrum was convolved with the Landsat ETM + spectral response curves and Moderate Resolution Imaging Spectrometer (MODIS) spectral response curves to obtain the simulated Landsat ETM+ and MODIS image. Finally, the simulated Landsat ETM+ and MODIS images were compared with the observed Landsat ETM+ and MODIS images. The results generally showed high correction coefficients (Landsat: 0.90-0.99, MODIS: 0.74-0.85) between most simulated bands and observed bands and indicated that the simulated reflectance spectrum was well simulated and reliable.

  15. Coded aperture imaging: the modulation transfer function for uniformly redundant arrays

    International Nuclear Information System (INIS)

    Fenimore, E.E.

    1980-01-01

    Coded aperture imaging uses many pinholes to increase the SNR for intrinsically weak sources when the radiation can be neither reflected nor refracted. Effectively, the signal is multiplexed onto an image and then decoded, often by a computer, to form a reconstructed image. We derive the modulation transfer function (MTF) of such a system employing uniformly redundant arrays (URA). We show that the MTF of a URA system is virtually the same as the MTF of an individual pinhole regardless of the shape or size of the pinhole. Thus, only the location of the pinholes is important for optimum multiplexing and decoding. The shape and size of the pinholes can then be selected based on other criteria. For example, one can generate self-supporting patterns, useful for energies typically encountered in the imaging of laser-driven compressions or in soft x-ray astronomy. Such patterns contain holes that are all the same size, easing the etching or plating fabrication efforts for the apertures. A new reconstruction method is introduced called delta decoding. It improves the resolution capabilities of a coded aperture system by mitigating a blur often introduced during the reconstruction step

  16. Transfer, imaging, and analysis plate for facile handling of 384 hanging drop 3D tissue spheroids.

    Science.gov (United States)

    Cavnar, Stephen P; Salomonsson, Emma; Luker, Kathryn E; Luker, Gary D; Takayama, Shuichi

    2014-04-01

    Three-dimensional culture systems bridge the experimental gap between in vivo and in vitro physiology. However, nonstandardized formation and limited downstream adaptability of 3D cultures have hindered mainstream adoption of these systems for biological applications, especially for low- and moderate-throughput assays commonly used in biomedical research. Here we build on our recent development of a 384-well hanging drop plate for spheroid culture to design a complementary spheroid transfer and imaging (TRIM) plate. The low-aspect ratio wells of the TRIM plate facilitated high-fidelity, user-independent, contact-based collection of hanging drop spheroids. Using the TRIM plate, we demonstrated several downstream analyses, including bulk tissue collection for flow cytometry, high-resolution low working-distance immersion imaging, and timely reagent delivery for enzymatic studies. Low working-distance multiphoton imaging revealed a cell type-dependent, macroscopic spheroid structure. Unlike ovarian cancer spheroids, which formed loose, disk-shaped spheroids, human mammary fibroblasts formed tight, spherical, and nutrient-limited spheroids. Beyond the applications we describe here, we expect the hanging drop spheroid plate and complementary TRIM plate to facilitate analyses of spheroids across the spectrum of throughput, particularly for bulk collection of spheroids and high-content imaging.

  17. Variation of the count-dependent Metz filter with imaging system modulation transfer function

    International Nuclear Information System (INIS)

    King, M.A.; Schwinger, R.B.; Penney, B.C.

    1986-01-01

    A systematic investigation was conducted of how a number of parameters which alter the system modulation transfer function (MTF) influence the count-dependent Metz filter. Since restoration filters are most effective at those frequencies where the object power spectrum dominates that of the noise, it was observed that parameters which significantly degrade the MTF at low spatial frequencies strongly influence the formation of the Metz filter. Thus the radionuclide imaged and the depth of the source in a scattering medium had the most influence. This is because they alter the relative amount of scattered radiation being imaged. For low-energy photon emitters, the collimator employed and the distance from the collimator were found to have less of an influence but still to be significant. These cause alterations in the MTF which are more gradual, and hence are most pronounced at mid to high spatial frequencies. As long as adequate spatial sampling is employed, the Metz filter was determined to be independent of the exact size of the sampling bin width, to a first approximation. For planar and single photon emission computed tomographic (SPECT) imaging, it is shown that two-dimensional filtering with the Metz filter optimized for the imaging conditions is able to deconvolve scatter and other causes of spatial resolution loss while diminishing noise, all in a balanced manner

  18. The progress in diagnostic imaging for staging of bladder and prostate cancer. Endorectal magnetic resonance imaging and magnetization transfer contrast

    International Nuclear Information System (INIS)

    Arima, Kiminobu; Hayashi, Norio; Yanagawa, Makoto; Kawamura, Juichi; Kobayashi, Shigeki; Takeda, Kan; Sugimura, Yoshiki

    1999-01-01

    We retrospectively studied the staging accuracy of endorectal magnetic resonance imaging (MRI) in comparison with transrectal ultrasound examination (TRUS) for 71 localized bladder cancers and 19 localized prostate cancers (PC) radically resected. The accuracy of clinical staging for bladder cancer in endorectal MRI and TRUS was 85.9% and 69.2%, respectively. The presence or absence of the continuity of submucosal enhancement on T2-weighted MRI images could be useful for the staging of bladder cancer. The accuracy of the seminal vesicular invasion for prostate cancer in endorectal MRI and TRUS was 95% and 63%, respectively. To determine whether magnetization transfer contrast (MTC) provides additional information in the diagnosis of prostate cancer, the magnetization transfer ratios (MTRs) were calculated in 22 patients with PC, 5 with benign prostatic hyperplasia (BPH) and 4 controls. The mean MTR in the peripheral zone of the normal prostate (8.0%±3.4 [standard deviation]) showed a statistically significant decrease relative to that in the inner zone of the normal prostate (27.4%±3.4, p<0.01), BPH (25.5%±3.7, p<0.01), pre-treatment PC (30.6%±5.9, p<0.01), and PC after hormonal therapy (20.3%±6.3, p<0.01). The mean MTR in pre-treatment PC was significantly higher than that in BPH, or in PC after hormonal therapy (p<0.01). MTC was considered to be useful for conspicuity of prostate cancer lesion. (author)

  19. Cellular transfer of magnetic nanoparticles via cell microvesicles: impact on cell tracking by magnetic resonance imaging.

    Science.gov (United States)

    Silva, Amanda K Andriola; Wilhelm, Claire; Kolosnjaj-Tabi, Jelena; Luciani, Nathalie; Gazeau, Florence

    2012-05-01

    Cell labeling with magnetic nanoparticles can be used to monitor the fate of transplanted cells in vivo by magnetic resonance imaging. However, nanoparticles initially internalized in administered cells might end up in other cells of the host organism. We investigated a mechanism of intercellular cross-transfer of magnetic nanoparticles to different types of recipient cells via cell microvesicles released under cellular stress. Three cell types (mesenchymal stem cells, endothelial cells and macrophages) were labeled with 8-nm iron oxide nanoparticles. Then cells underwent starvation stress, during which they produced microvesicles that were subsequently transferred to unlabeled recipient cells. The analysis of the magnetophoretic mobility of donor cells indicated that magnetic load was partially lost under cell stress. Microvesicles shed by stressed cells participated in the release of magnetic label. Moreover, such microvesicles were uptaken by naïve cells, resulting in cellular redistribution of nanoparticles. Iron load of recipient cells allowed their detection by MRI. Cell microvesicles released under stress may be disseminated throughout the organism, where they can be uptaken by host cells. The transferred cargo may be sufficient to allow MRI detection of these secondarily labeled cells, leading to misinterpretations of the effectiveness of transplanted cells.

  20. Conversion from film to image plates for transfer method neutron radiography of nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Craft, Aaron E.; Papaioannou, Glen C.; Chichester, David L.; Williams, Walter J.

    2017-02-01

    This paper summarizes efforts to characterize and qualify a computed radiography (CR) system for neutron radiography of irradiated nuclear fuel at Idaho National Laboratory (INL). INL has multiple programs that are actively developing, testing, and evaluating new nuclear fuels. Irradiated fuel experiments are subjected to a number of sequential post-irradiation examination techniques that provide insight into the overall behavior and performance of the fuel. One of the first and most important of these exams is neutron radiography, which provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Results from neutron radiography are often the driver for subsequent examinations of the PIE program. Features of interest that can be evaluated using neutron radiography include irradiation-induced swelling, isotopic and fuel-fragment redistribution, plate deformations, and fuel fracturing. The NRAD currently uses the foil-film transfer technique with film for imaging fuel. INL is pursuing multiple efforts to advance its neutron imaging capabilities for evaluating irradiated fuel and other applications, including conversion from film to CR image plates. Neutron CR is the current state-of-the-art for neutron imaging of highly-radioactive objects. Initial neutron radiographs of various types of nuclear fuel indicate that radiographs can be obtained of comparable image quality currently obtained using film. This paper provides neutron radiographs of representative irradiated fuel pins along with neutron radiographs of standards that informed the qualification of the neutron CR system for routine use. Additionally, this paper includes evaluations of some of the CR scanner parameters and their effects on image quality.

  1. Longitudinal assessment of mouse renal injury using high-resolution anatomic and magnetization transfer MR imaging.

    Science.gov (United States)

    Wang, Feng; Jiang, Rosie; Takahashi, Keiko; Gore, John; Harris, Raymond C; Takahashi, Takamune; Quarles, C Chad

    2014-11-01

    The purpose of this study is to evaluate the utility of high-resolution non-invasive endogenous high-field MRI methods for the longitudinal structural and quantitative assessments of mouse kidney disease using the model of unilateral ureter obstruction (UUO). T1-weighted, T2-weighted and magnetization transfer (MT) imaging protocols were optimized to improve the regional contrast in mouse kidney. Conventional T1 and T2 weighted images were collected in UUO mice on day 0 (~3h), day 1, day 3 and day 6 after injury, on a 7 T small animal MRI system. Cortical and medullary thickness, corticomedullary contrast and Magnetization Transfer Ratio (MTR) were assessed longitudinally. Masson trichrome staining was used to histologically assess changes in tissue microstructure. Over the course of UUO progression there were significant (prenal cortical and medullary atrophy, cortical-medullary differentiation and MTR changes provide an endogenous, non-invasive and quantitative evaluation of renal morphology and tissue composition during UUO progression. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Characterizing amide proton transfer imaging in haemorrhage brain lesions using 3T MRI

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ha-Kyu [Philips Korea, Seoul (Korea, Republic of); Korea Basic Science Institute, Chungcheongbuk-do (Korea, Republic of); Han, Kyunghwa [Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, Seodaemun-gu, Seoul (Korea, Republic of); Yonsei University College of Medicine, Yonsei Biomedical Research Institute, Seoul (Korea, Republic of); Zhou, Jinyuan [Johns Hopkins University School of Medicine, Division of MRI Research, Department of Radiology, Baltimore, MD (United States); Zhao, Yansong [Philips Healthcare, MR Clinical Science, Cleveland, OH (United States); Choi, Yoon Seong; Lee, Seung-Koo; Ahn, Sung Soo [Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, Seodaemun-gu, Seoul (Korea, Republic of)

    2017-04-15

    The aim of this study was to characterize amide proton transfer (APT)-weighted signals in acute and subacute haemorrhage brain lesions of various underlying aetiologies. Twenty-three patients with symptomatic haemorrhage brain lesions including tumorous (n = 16) and non-tumorous lesions (n = 7) were evaluated. APT imaging was performed and analyzed with magnetization transfer ratio asymmetry (MTR{sub asym}). Regions of interest were defined as the enhancing portion (when present), acute or subacute haemorrhage, and normal-appearing white matter based on anatomical MRI. MTR{sub asym} values were compared among groups and components using a linear mixed model. MTR{sub asym} values were 3.68 % in acute haemorrhage, 1.6 % in subacute haemorrhage, 2.65 % in the enhancing portion, and 0.38 % in normal white matter. According to the linear mixed model, the distribution of MTR{sub asym} values among components was not significantly different between tumour and non-tumour groups. MTR{sub asym} in acute haemorrhage was significantly higher than those in the other regions regardless of underlying pathology. Acute haemorrhages showed high MTR{sub asym} regardless of the underlying pathology, whereas subacute haemorrhages showed lower MTR{sub asym} than acute haemorrhages. These results can aid in the interpretation of APT imaging in haemorrhage brain lesions. (orig.)

  3. Multimodality pH imaging in a mouse dorsal skin fold window chamber model

    Science.gov (United States)

    Leung, Hui Min; Schafer, Rachel; Pagel, Mark M.; Robey, Ian F.; Gmitro, Arthur F.

    2013-03-01

    Upregulate levels of expression and activity of membrane H+ ion pumps in cancer cells drives the extracellular pH (pHe,) to values lower than normal. Furthermore, disregulated pH is indicative of the changes in glycolytic metabolism in tumor cells and has been shown to facilitate extracellular tissue remodeling during metastasis Therefore, measurement of pHe could be a useful cancer biomarker for diagnostic and therapy monitoring evaluation. Multimodality in-vivo imaging of pHe in tumorous tissue in a mouse dorsal skin fold window chamber (DSFWC) model is described. A custom-made plastic window chamber structure was developed that is compatible with both imaging optical and MR imaging modalities and provides a model system for continuous study of the same tissue microenvironment on multiple imaging platforms over a 3-week period. For optical imaging of pHe, SNARF-1 carboxylic acid is injected intravenously into a SCID mouse with an implanted tumor. A ratiometric measurement of the fluorescence signal captured on a confocal microscope reveals the pHe of the tissue visible within the window chamber. This imaging method was used in a preliminary study to evaluate sodium bicarbonate as a potential drug treatment to reverse tissue acidosis. For MR imaging of pHe the chemical exchange saturation transfer (CEST) was used as an alternative way of measuring pHe in a DSFWC model. ULTRAVIST®, a FDA approved x-ray/CT contrast agent has been shown to have a CEST effect that is pH dependent. A ratiometric analysis of water saturation at 5.6 and 4.2 ppm chemical shift provides a means to estimate the local pHe.

  4. Multiparametric and molecular imaging of breast tumors with MRI and PET/MRI

    International Nuclear Information System (INIS)

    Pinker, K.; Marino, M.A.; Meyer-Baese, A.; Helbich, T.H.

    2016-01-01

    Magnetic resonance imaging (MRI) of the breast is an indispensable tool in breast imaging for many indications. Several functional parameters with MRI and positron emission tomography (PET) have been assessed for imaging of breast tumors and their combined application is defined as multiparametric imaging. Available data suggest that multiparametric imaging using different functional MRI and PET parameters can provide detailed information about the hallmarks of cancer and may provide additional specificity. Multiparametric and molecular imaging of the breast comprises established MRI parameters, such as dynamic contrast-enhanced MRI, diffusion-weighted imaging (DWI), MR proton spectroscopy ( 1 H-MRSI) as well as combinations of radiological and MRI techniques (e.g. PET/CT and PET/MRI) using radiotracers, such as fluorodeoxyglucose (FDG). Multiparametric and molecular imaging of the breast can be performed at different field-strengths (range 1.5-7 T). Emerging parameters comprise novel promising techniques, such as sodium imaging ( 23 Na MRI), phosphorus spectroscopy ( 31 P-MRSI), chemical exchange saturation transfer (CEST) imaging, blood oxygen level-dependent (BOLD) and hyperpolarized MRI as well as various specific radiotracers. Multiparametric and molecular imaging has multiple applications in breast imaging. Multiparametric and molecular imaging of the breast is an evolving field that will enable improved detection, characterization, staging and monitoring for personalized medicine in breast cancer. (orig.) [de

  5. The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis.

    Science.gov (United States)

    Wang, Fusong; Wang, Zipeng; Li, Chao; Xiao, Yue; Wu, Shaopeng; Pan, Pan

    2017-05-24

    Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4-8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling.

  6. Anatomy of the Java plate interface from depth-migrated seismic images: Implications for sediment transfer

    Science.gov (United States)

    Kopp, H.; Hindle, D.; Klaeschen, D.; Oncken, O.; Reichert, C.; Scholl, D.

    2008-12-01

    We present seismic data from the western Java margin off Indonesia. The newly pre-stack depth migrated seismic images resolve the structural details of the western Java forearc and the fate of sediment subducted at the trench. Approximately 2/3 of the trench sediment fill is detached and incorporated into frontal prism imbricates, while the floor sequence is transported down a subduction channel. Basal mass transfer occurs by episodic accretion of sediment beneath the submerged forearc as the active detachment stepwise descends to a deeper level below the outer wedge. Fluctuations in subduction channel dimensions are enhanced by deep-reaching thrust faults that are traced from a velocity singularity marking the top of the oceanic basement towards the seafloor. These thrust faults breach the subduction channel and inhibit recycling of material to mantle depth, while serving as an incremental ramp along which the active detachment is transferred to a lower position. The high ratio of accreted/subducted sediment is associated with the evolution of a large bivergent wedge (>100 km) despite the comparatively low sediment input to the trench (<2 km). We used quantitative DEM modeling to gain some insight into the evolution of the distinct tectonic units. In the modelling, initiation of sediment accretion occurs against the arc rock framework, which is imaged in the MCS data. Overthrusting of the wedge onto the forearc basin is also expressed in a prominent retro-thrust imaged in the seismic data. The seismic data document an end-member type of subduction zone where near-complete accretion of the trench sediment fill by frontal and basal accretion is supported by the lack of evidence for subducted sediment in the geochemical signature of Mt. Guntur and Mt. Gallunggung, two volcanoes positioned in the prolongation of our seismic line on Java.

  7. Applying protein-based amide proton transfer MR imaging to distinguish solitary brain metastases from glioblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hao; Zou, Tianyu; Wang, Xianlong; Du, Yongxing; Jiang, Chunxiu; Ma, Ling; Zhu, Jianbin; He, Wen; Rui, Qihong; Wen, Zhibo [Zhujiang Hospital, Southern Medical University, Department of Radiology, Guangzhou, Guangdong (China); Lou, Huiling [The First People' Hospital of Guangzhou, Department of Geriatrics, Guangzhou, Guangdong (China); Jiang, Shanshan [Zhujiang Hospital, Southern Medical University, Department of Radiology, Guangzhou, Guangdong (China); Johns Hopkins University School of Medicine, Division of MR Research, Department of Radiology, Baltimore, MD (United States); Huang, Zhongqing [Shantou University Medical College, Department of Medical Image Center, Yuebei People' s Hospital, Shantou, Guangdong (China); Zhou, Jianyuan [Johns Hopkins University School of Medicine, Division of MR Research, Department of Radiology, Baltimore, MD (United States)

    2017-11-15

    To determine the utility of amide proton transfer-weighted (APTw) MR imaging in distinguishing solitary brain metastases (SBMs) from glioblastomas (GBMs). Forty-five patients with SBMs and 43 patients with GBMs underwent conventional and APT-weighted sequences before clinical intervention. The APTw parameters and relative APTw (rAPTw) parameters in the tumour core and the peritumoral brain zone (PBZ) were obtained and compared between SBMs and GBMs. The receiver-operating characteristic (ROC) curve was used to assess the best parameter for distinguishing between the two groups. The APTw{sub max}, APTw{sub min}, APTw{sub mean}, rAPTw{sub max}, rAPTw{sub min} or rAPTw{sub mean} values in the tumour core were not significantly different between the SBM and GBM groups (P = 0.141, 0.361, 0.221, 0.305, 0.578 and 0.448, respectively). However, the APTw{sub max}, APTw{sub min}, APTw{sub mean}, rAPTw{sub max}, rAPTw{sub min} or rAPTw{sub mean} values in the PBZ were significantly lower in the SBM group than in the GBM group (P < 0.001). The APTw{sub min} values had the highest area under the ROC curve 0.905 and accuracy 85.2% in discriminating between the two neoplasms. As a noninvasive imaging method, APT-weighted MR imaging can be used to distinguish SBMs from GBMs. (orig.)

  8. An optimized framework for quantitative magnetization transfer imaging of the cervical spinal cord in vivo.

    Science.gov (United States)

    Battiston, Marco; Grussu, Francesco; Ianus, Andrada; Schneider, Torben; Prados, Ferran; Fairney, James; Ourselin, Sebastien; Alexander, Daniel C; Cercignani, Mara; Gandini Wheeler-Kingshott, Claudia A M; Samson, Rebecca S

    2018-05-01

    To develop a framework to fully characterize quantitative magnetization transfer indices in the human cervical cord in vivo within a clinically feasible time. A dedicated spinal cord imaging protocol for quantitative magnetization transfer was developed using a reduced field-of-view approach with echo planar imaging (EPI) readout. Sequence parameters were optimized based in the Cramer-Rao-lower bound. Quantitative model parameters (i.e., bound pool fraction, free and bound pool transverse relaxation times [ T2F, T2B], and forward exchange rate [k FB ]) were estimated implementing a numerical model capable of dealing with the novelties of the sequence adopted. The framework was tested on five healthy subjects. Cramer-Rao-lower bound minimization produces optimal sampling schemes without requiring the establishment of a steady-state MT effect. The proposed framework allows quantitative voxel-wise estimation of model parameters at the resolution typically used for spinal cord imaging (i.e. 0.75 × 0.75 × 5 mm 3 ), with a protocol duration of ∼35 min. Quantitative magnetization transfer parametric maps agree with literature values. Whole-cord mean values are: bound pool fraction = 0.11(±0.01), T2F = 46.5(±1.6) ms, T2B = 11.0(±0.2) µs, and k FB  = 1.95(±0.06) Hz. Protocol optimization has a beneficial effect on reproducibility, especially for T2B and k FB . The framework developed enables robust characterization of spinal cord microstructure in vivo using qMT. Magn Reson Med 79:2576-2588, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc

  9. Error of the slanted edge method for measuring the modulation transfer function of imaging systems.

    Science.gov (United States)

    Xie, Xufen; Fan, Hongda; Wang, Hongyuan; Wang, Zebin; Zou, Nianyu

    2018-03-01

    The slanted edge method is a basic approach for measuring the modulation transfer function (MTF) of imaging systems; however, its measurement accuracy is limited in practice. Theoretical analysis of the slanted edge MTF measurement method performed in this paper reveals that inappropriate edge angles and random noise reduce this accuracy. The error caused by edge angles is analyzed using sampling and reconstruction theory. Furthermore, an error model combining noise and edge angles is proposed. We verify the analyses and model with respect to (i) the edge angle, (ii) a statistical analysis of the measurement error, (iii) the full width at half-maximum of a point spread function, and (iv) the error model. The experimental results verify the theoretical findings. This research can be referential for applications of the slanted edge MTF measurement method.

  10. A technique for transferring a patient's smile line to a cone beam computed tomography (CBCT) image.

    Science.gov (United States)

    Bidra, Avinash S

    2014-08-01

    Fixed implant-supported prosthodontic treatment for patients requiring a gingival prosthesis often demands that bone and implant levels be apical to the patient's maximum smile line. This is to avoid the display of the prosthesis-tissue junction (the junction between the gingival prosthesis and natural soft tissues) and prevent esthetic failures. Recording a patient's lip position during maximum smile is invaluable for the treatment planning process. This article presents a simple technique for clinically recording and transferring the patient's maximum smile line to cone beam computed tomography (CBCT) images for analysis. The technique can help clinicians accurately determine the need for and amount of bone reduction required with respect to the maximum smile line and place implants in optimal positions. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  11. Live embryo imaging to follow cell cycle and chromosomes stability after nuclear transfer.

    Science.gov (United States)

    Balbach, Sebastian T; Boiani, Michele

    2015-01-01

    Nuclear transfer (NT) into mouse oocytes yields a transcriptionally and functionally heterogeneous population of cloned embryos. Most studies of NT embryos consider only embryos at predefined key stages (e.g., morula or blastocyst), that is, after the bulk of reprogramming has taken place. These retrospective approaches are of limited use to elucidate mechanisms of reprogramming and to predict developmental success. Observing cloned embryo development using live embryo cinematography has the potential to reveal otherwise undetectable embryo features. However, light exposure necessary for live cell cinematography is highly toxic to cloned embryos. Here we describe a protocol for combined bright-field and fluorescence live-cell imaging of histone H2b-GFP expressing mouse embryos, to record cell divisions up to the blastocyst stage. This protocol, which can be adapted to observe other reporters such as Oct4-GFP or Nanog-GFP, allowed us to quantitatively analyze cleavage kinetics of cloned embryos.

  12. Magnetization transfer imaging of periventricular white matter lesions in patients with multi-infarct dementia

    International Nuclear Information System (INIS)

    Hanyu, Haruo; Imon, Yukari; Asano, Tetsuichi; Iwamoto, Toshihiko; Takasaki, Masaru

    1998-01-01

    Using magnetization transfer (MT) imaging, we studied the underlying pathological conditions of periventricular hyperintense (PVH) white matter changes seen on T2-weighted MR images of patients with multi-infarct dementia. Twenty-two patients with multiple lacunar infarcts and PVH lesions, including 11 with dementia (diagnosed as multi-infarct dementia) and 11 without dementia, and 10 control subjects (with multiple lacunes, but no PVH lesion) were studied using the MT technique. MT ratios (MTRs) were calculated for PVH lesions (normal-appearing frontal white matter in controls) and the genu of the corpus callosum. Signal intensities on T2-weighted images in PVH lesions of patients were significantly higher than those in normal-appearing white matter of controls, while there were no significant differences in signal intensity in the genu of the corpus callosum among the dementia, non-dementia and control groups. However, MTRs in patients with PVH lesions were significantly lower than those in controls, and MTRs in demented patients were significantly lower than those in non-demented patients. Moreover, MTRs in the genu of the corpus callosum of demented patients were significantly lower than in those in non-demented patients and controls. MTRs in PVH lesions and the genu of the corpus callosum significantly correlated with Hasegawa's dementia scale score. These results suggest that there is some difference in histopathologic changes of PVH lesions between demented and non-demented patients and that the pathological substrate in the corpus callosum may play a role in inducing cognitive decline. Studies with MT imaging may allow the characterization of different pathological conditions that cannot be visualized by conventional MRI. (author)

  13. Is white matter affected in adolescents with anorexia nervosa? A study using magnetization transfer imaging.

    Science.gov (United States)

    Akgül, Sinem; Öz, Ayşegül; Karlı-Oğuz, Kader; Kanbur, Nuray; Derman, Orhan

    2016-01-01

    The aim of the study was to assess potential changes in structural integrity of the brain in adolescent patients with Anorexia Nervosa (AN) using the magnetization transfer imaging technique and re-evaluating after nutritional rehabilitation was accomplished. Magnetization transfer ratio (MTR) was used for the detection and quantification of histological changes to the white matter of 9 adolescents diagnosed with AN at diagnosis and after weight gain. Using the MTR technique 6 regions were measured: the pons, left cerebellar hemisphere, amygdala, thalamus, corona radiata and white matter adjacent to the left dorsolateral prefrontal cortex. Scans from the patients with AN were also compared with scans from an age-matched subset of 9 healthy controls. Compared with control subjects, the MTR of participants with AN was no different either at the early stages of diagnosis (p=0.62) or after weight recovery (p=0.81). Similarly, comparison of MTR between patients with AN at diagnoses compared with MTR after weight recovery yielded no statistically significant difference (P=0.33). We conclude that MTR was not able to detect any neuropathological alterations in adolescent patients with AN at either diagnosis or after nutritional recovery and the achievement of weight gain.

  14. An investigation of heat transfer between a microcantilever and a substrate for improved thermal topography imaging

    International Nuclear Information System (INIS)

    Somnath, Suhas; King, William P

    2014-01-01

    This paper reports the numerical and experimental investigation of heat transfer from a heated microcantilever to a substrate and uses the resulting insights to improve thermal topography imaging. The cantilever sensitivity, defined as change in thermal signal due to changes in the topography height, is relatively constant for feature heights in the range 100–350 nm. Since the cantilever-substrate heat transfer is governed by thermal conduction through the air, the cantilever sensitivity is nearly constant across substrates of varying thermal conductivity. Surface features with lateral size larger than 2.5 μm can induce artifacts in the cantilever signal resulting in measurement errors as large as 28%. These artifacts arise from thermal conduction from the cantilever in the lateral direction, parallel to the surface. We show how these artifacts can be removed by accounting for this lateral conduction and removing it from the thermal signal. This technique reduces the measurement error by as much as 26%, can be applied to arbitrary substrate topographies, and can be scaled to arrays of heated cantilevers. These results could lead to improvements in nanometer-scale thermal measurements including scanning thermal microscopy and tip-based nanofabrication. (paper)

  15. Quantitative magnetization transfer imaging of rodent glioma using selective inversion recovery.

    Science.gov (United States)

    Xu, Junzhong; Li, Ke; Zu, Zhongliang; Li, Xia; Gochberg, Daniel F; Gore, John C

    2014-03-01

    Magnetization transfer (MT) provides an indirect means to detect noninvasively variations in macromolecular contents in biological tissues, but, so far, there have been only a few quantitative MT (qMT) studies reported in cancer, all of which used off-resonance pulsed saturation methods. This article describes the first implementation of a different qMT approach, selective inversion recovery (SIR), for the characterization of tumor in vivo using a rodent glioma model. The SIR method is an on-resonance method capable of fitting qMT parameters and T1 relaxation time simultaneously without mapping B0 and B1 , which is very suitable for high-field qMT measurements because of the lower saturation absorption rate. The results show that the average pool size ratio (PSR, the macromolecular pool versus the free water pool) in rat 9 L glioma (5.7%) is significantly lower than that in normal rat gray matter (9.2%) and white matter (17.4%), which suggests that PSR is potentially a sensitive imaging biomarker for the assessment of brain tumor. Despite being less robust, the estimated MT exchange rates also show clear differences from normal tissues (19.7 Hz for tumors versus 14.8 and 10.2 Hz for gray and white mater, respectively). In addition, the influence of confounding effects, e.g. B1 inhomogeneity, on qMT parameter estimates is investigated with numerical simulations. These findings not only help to better understand the changes in the macromolecular contents of tumors, but are also important for the interpretation of other imaging contrasts, such as chemical exchange saturation transfer of tumors. Copyright © 2013 John Wiley & Sons, Ltd.

  16. Experimental measurement of the interfacial heat transfer coefficients of subcooled flow boiling using micro-thermocouple and double directional images

    International Nuclear Information System (INIS)

    Seong-Jin Kim; Goon-Cherl Park

    2005-01-01

    Full text of publication follows: Models or correlations for phase interface are needed to analyze the multi-phase flow. Interfacial heat transfer coefficients are important to constitute energy equation of multi-phase flow, specially. In subcooled boiling flow, bubble condensation at the bubble-liquid interface is a major mechanism of heat transfer within bulk subcooled liquid. Bubble collapse rates and temperatures of each phase are needed to determine the interfacial heat transfer coefficient for bubble condensation. Bubble collapse rates were calculated through image processing in single direction, generally. And in case of liquid bulk temperature, which has been obtained by general temperature sensor such as thermocouple, was used. However, multi-directional images are needed to analyze images due to limitations of single directional image processing. Also, temperature sensor, which has a fast response time, must be used to obtain more accurate interfacial heat transfer coefficient. Low pressure subcooled water flow experiments using micro-thermocouple and double directional image processing with mirrors were conducted to investigate bubble condensation phenomena and to modify interfacial heat transfer correlation. Experiments were performed in a vertical subcooled boiling flow of a rectangular channel. Bubble condensing traces with respect to time were recorded by high speed camera in double direction and bubble collapse rates were calculated by processing recorded digital images. Temperatures were measured by micro-thermocouple, which is a K-type with a 12.7 μm diameter. The liquid temperature was estimated by the developed algorithm to discriminate phases and find each phase temperature in the measured temperature including both liquid and bubble temperature. The interfacial heat transfer coefficient for bubble condensation was calculated from the bubble collapse rates and the estimated liquid temperature, and its correlation was modified. The modified

  17. Recent Advances in Nanoparticle-Based Förster Resonance Energy Transfer for Biosensing, Molecular Imaging and Drug Release Profiling

    Directory of Open Access Journals (Sweden)

    Nai-Tzu Chen

    2012-12-01

    Full Text Available Förster resonance energy transfer (FRET may be regarded as a “smart” technology in the design of fluorescence probes for biological sensing and imaging. Recently, a variety of nanoparticles that include quantum dots, gold nanoparticles, polymer, mesoporous silica nanoparticles and upconversion nanoparticles have been employed to modulate FRET. Researchers have developed a number of “visible” and “activatable” FRET probes sensitive to specific changes in the biological environment that are especially attractive from the biomedical point of view. This article reviews recent progress in bringing these nanoparticle-modulated energy transfer schemes to fruition for applications in biosensing, molecular imaging and drug delivery.

  18. An excited-state intramolecular photon transfer fluorescence probe for localizable live cell imaging of cysteine

    Science.gov (United States)

    Liu, Wei; Chen, Wen; Liu, Si-Jia; Jiang, Jian-Hui

    2017-03-01

    Small molecule probes suitable for selective and specific fluorescence imaging of some important but low-concentration intracellular reactive sulfur species such as cysteine (Cys) pose a challenge in chemical biology. We present a readily available, fast-response fluorescence probe CHCQ-Ac, with 2-(5‧-chloro-2-hydroxyl-phenyl)-6-chloro-4(3 H)-quinazolinone (CHCQ) as the fluorophore and acrylate group as the functional moiety, that enables high-selectivity and high-sensitivity for detecting Cys in both solution and biological system. After specifically reacted with Cys, the probe undergoes a seven-membered intramolecular cyclization and released the fluorophore CHCQ with excited-state intramolecular photon transfer effect. A highly fluorescent, insoluble aggregate was then formed to facilitate high-sensitivity and high-resolution imaging. The results showed that probe CHCQ-Ac affords a remarkably large Stokes shift and can detect Cys under physiological pH condition with no interference from other analytes. Moreover, this probe was proved to have excellent chemical stability, low cytotoxicity and good cell permeability. Our design of this probe provides a novel potential tool to visualize and localize cysteine in bioimaging of live cells that would greatly help to explore various Cys-related physiological and pathological cellular processes in cell biology and diagnostics.

  19. Magnetisation transfer imaging of the normal adenohypophysis: the effect of sex and age

    Energy Technology Data Exchange (ETDEWEB)

    Argyropoulou, M.I.; Metafratzi, Z.; Efremidis, S.C. [Dept. of Radiology, Medical School, University of Ioannina (Greece); Kiortsis, D.N. [Lab. of Physiology, Medical School, University of Ioannina (Greece)

    2001-04-01

    Magnetisation transfer (MT) techniques provide tissue contrast depending mainly on the concentration of macromolecules. Because many macromolecules are involved in the secretory activity of the pituitary gland, MT techniques might be useful in the study of pituitary gland disorders. Our purpose was to establish a quantitative database of the MT ratio (MTR) of the normal adenohypophysis and to see whether there are age- and sex-related differences. Using a three-dimensional gradient-echo sequence for MT we studied the adenohypophysis in 56 males and 61 females aged 7 months-77 years; postsaturation images were obtained using an on-resonance binomial prepulse. The images were normal in all but three patients, two with meningiomas, one with a schwannoma. Adenohypophyseal MTR increased in both sexes up to 19 years of age (r = 0.47 males, 0.39 females, P < 0.05). In men after 20 years and in women from 20-49 years MTR decreased (r = -0.68, P < 0.001, r = -0.46, P < 0.05, respectively). In women aged 50-59 years the MTR again increased slightly. The MTR in males was slightly higher at all ages except before 9 and after 50 years of age. These differences were not statistically significant except in the 40-49 year group (P < 0.05). (orig.)

  20. Simulation of seagrass bed mapping by satellite images based on the radiative transfer model

    Science.gov (United States)

    Sagawa, Tatsuyuki; Komatsu, Teruhisa

    2015-06-01

    Seagrass and seaweed beds play important roles in coastal marine ecosystems. They are food sources and habitats for many marine organisms, and influence the physical, chemical, and biological environment. They are sensitive to human impacts such as reclamation and pollution. Therefore, their management and preservation are necessary for a healthy coastal environment. Satellite remote sensing is a useful tool for mapping and monitoring seagrass beds. The efficiency of seagrass mapping, seagrass bed classification in particular, has been evaluated by mapping accuracy using an error matrix. However, mapping accuracies are influenced by coastal environments such as seawater transparency, bathymetry, and substrate type. Coastal management requires sufficient accuracy and an understanding of mapping limitations for monitoring coastal habitats including seagrass beds. Previous studies are mainly based on case studies in specific regions and seasons. Extensive data are required to generalise assessments of classification accuracy from case studies, which has proven difficult. This study aims to build a simulator based on a radiative transfer model to produce modelled satellite images and assess the visual detectability of seagrass beds under different transparencies and seagrass coverages, as well as to examine mapping limitations and classification accuracy. Our simulations led to the development of a model of water transparency and the mapping of depth limits and indicated the possibility for seagrass density mapping under certain ideal conditions. The results show that modelling satellite images is useful in evaluating the accuracy of classification and that establishing seagrass bed monitoring by remote sensing is a reliable tool.

  1. Magnetisation transfer imaging of the normal adenohypophysis: the effect of sex and age

    International Nuclear Information System (INIS)

    Argyropoulou, M.I.; Metafratzi, Z.; Efremidis, S.C.; Kiortsis, D.N.

    2001-01-01

    Magnetisation transfer (MT) techniques provide tissue contrast depending mainly on the concentration of macromolecules. Because many macromolecules are involved in the secretory activity of the pituitary gland, MT techniques might be useful in the study of pituitary gland disorders. Our purpose was to establish a quantitative database of the MT ratio (MTR) of the normal adenohypophysis and to see whether there are age- and sex-related differences. Using a three-dimensional gradient-echo sequence for MT we studied the adenohypophysis in 56 males and 61 females aged 7 months-77 years; postsaturation images were obtained using an on-resonance binomial prepulse. The images were normal in all but three patients, two with meningiomas, one with a schwannoma. Adenohypophyseal MTR increased in both sexes up to 19 years of age (r = 0.47 males, 0.39 females, P < 0.05). In men after 20 years and in women from 20-49 years MTR decreased (r = -0.68, P < 0.001, r = -0.46, P < 0.05, respectively). In women aged 50-59 years the MTR again increased slightly. The MTR in males was slightly higher at all ages except before 9 and after 50 years of age. These differences were not statistically significant except in the 40-49 year group (P < 0.05). (orig.)

  2. Characterization of adaptive statistical iterative reconstruction (ASIR) in low contrast helical abdominal imaging via a transfer function based method

    Science.gov (United States)

    Zhang, Da; Li, Xinhua; Liu, Bob

    2012-03-01

    Since the introduction of ASiR, its potential in noise reduction has been reported in various clinical applications. However, the influence of different scan and reconstruction parameters on the trade off between ASiR's blurring effect and noise reduction in low contrast imaging has not been fully studied. Simple measurements on low contrast images, such as CNR or phantom scores could not explore the nuance nature of this problem. We tackled this topic using a method which compares the performance of ASiR in low contrast helical imaging based on an assumed filter layer on top of the FBP reconstruction. Transfer functions of this filter layer were obtained from the noise power spectra (NPS) of corresponding FBP and ASiR images that share the same scan and reconstruction parameters. 2D transfer functions were calculated as sqrt[NPSASiR(u, v)/NPSFBP(u, v)]. Synthesized ACR phantom images were generated by filtering the FBP images with the transfer functions of specific (FBP, ASiR) pairs, and were compared with the ASiR images. It is shown that the transfer functions could predict the deterministic blurring effect of ASiR on low contrast objects, as well as the degree of noise reductions. Using this method, the influence of dose, scan field of view (SFOV), display field of view (DFOV), ASiR level, and Recon Mode on the behavior of ASiR in low contrast imaging was studied. It was found that ASiR level, dose level, and DFOV play more important roles in determining the behavior of ASiR than the other two parameters.

  3. Potential for increasing conspicuity of short-T1 lesions in the brain using magnetisation transfer imaging

    International Nuclear Information System (INIS)

    De Souza, N.M.; Hajnal, J.V.; Baudouin, C.J.

    1995-01-01

    We investigated the feasibility of using T1-weighted magnetisation transfer sequences to generate tissue contrast and increase the conspicuity of short-T1 areas within the brain. We imaged two normal volunteers with and without saturating off-resonance radiofrequency irradiation at a range of repetition times (TR 200-760 ms). T1 values and magnetisation transfer ratios for white matter and deep grey matter were calculated. We studied eight patients with intracranial lesions showing short-T1 areas, using mildly T1-weighted sequences with and without magnetisation transfer contrast. Lesion numbers, areas and signal intensities were measured and lesion-to-background contrast was calculated. Comparison was made with conventional T1-weighted spin-echo images. In the normal volunteers, contrast between the thalamus, caudate and lentiform nuclei and white matter showed striking visual differences, with magnetisation transfer weighting, with decreasing TR. In all patients, short-T1 lesions were seen more clearly on magnetisation transfer-weighted images, with significant increase in lesion number, area and contrast, when compared with conventional T1-weighted scans. (orig.)

  4. Simulation of Sentinel-3 images by four stream surface atmosphere radiative transfer modeling in the optical and thermal domains

    NARCIS (Netherlands)

    Verhoef, W.; Bach, H.

    2012-01-01

    Simulation of future satellite images can be applied in order to validate the general mission concept and to test the performance of advanced multi-sensor algorithms for the retrieval of surface parameters. This paper describes the radiative transfer modeling part of a so-called Land Scene Generator

  5. Delineation of cortical pathology in multiple sclerosis using multi-surface magnetization transfer ratio imaging

    Directory of Open Access Journals (Sweden)

    David A. Rudko

    2016-01-01

    Full Text Available The purpose of our study was to evaluate the utility of measurements of cortical surface magnetization transfer ratio (csMTR on the inner, mid and outer cortical boundaries as clinically accessible biomarkers of cortical gray matter pathology in multiple sclerosis (MS. Twenty-five MS patients and 12 matched controls were recruited from the MS Clinic of the Montreal Neurological Institute. Anatomical and magnetization transfer ratio (MTR images were acquired using 3 Tesla MRI at baseline and two-year time-points. MTR maps were smoothed along meshes representing the inner, mid and outer neocortical boundaries. To evaluate csMTR reductions suggestive of sub-pial demyelination in MS patients, a mixed model analysis was carried out at both the individual vertex level and in anatomically parcellated brain regions. Our results demonstrate that focal areas of csMTR reduction are most prevalent along the outer cortical surface in the superior temporal and posterior cingulate cortices, as well as in the cuneus and precentral gyrus. Additionally, age regression analysis identified that reductions of csMTR in MS patients increase with age but appear to hit a plateau in the outer caudal anterior cingulate, as well as in the precentral and postcentral cortex. After correction for the naturally occurring gradient in cortical MTR, the difference in csMTR between the inner and outer cortex in focal areas in the brains of MS patients correlated with clinical disability. Overall, our findings support multi-surface analysis of csMTR as a sensitive marker of cortical sub-pial abnormality indicative of demyelination in MS patients.

  6. A novel end-to-end classifier using domain transferred deep convolutional neural networks for biomedical images.

    Science.gov (United States)

    Pang, Shuchao; Yu, Zhezhou; Orgun, Mehmet A

    2017-03-01

    Highly accurate classification of biomedical images is an essential task in the clinical diagnosis of numerous medical diseases identified from those images. Traditional image classification methods combined with hand-crafted image feature descriptors and various classifiers are not able to effectively improve the accuracy rate and meet the high requirements of classification of biomedical images. The same also holds true for artificial neural network models directly trained with limited biomedical images used as training data or directly used as a black box to extract the deep features based on another distant dataset. In this study, we propose a highly reliable and accurate end-to-end classifier for all kinds of biomedical images via deep learning and transfer learning. We first apply domain transferred deep convolutional neural network for building a deep model; and then develop an overall deep learning architecture based on the raw pixels of original biomedical images using supervised training. In our model, we do not need the manual design of the feature space, seek an effective feature vector classifier or segment specific detection object and image patches, which are the main technological difficulties in the adoption of traditional image classification methods. Moreover, we do not need to be concerned with whether there are large training sets of annotated biomedical images, affordable parallel computing resources featuring GPUs or long times to wait for training a perfect deep model, which are the main problems to train deep neural networks for biomedical image classification as observed in recent works. With the utilization of a simple data augmentation method and fast convergence speed, our algorithm can achieve the best accuracy rate and outstanding classification ability for biomedical images. We have evaluated our classifier on several well-known public biomedical datasets and compared it with several state-of-the-art approaches. We propose a robust

  7. Pulsed magnetization transfer imaging with body coil transmission at 3 Tesla: feasibility and application.

    Science.gov (United States)

    Smith, Seth A; Farrell, Jonathan A D; Jones, Craig K; Reich, Daniel S; Calabresi, Peter A; van Zijl, Peter C M

    2006-10-01

    Pulsed magnetization transfer (MT) imaging has been applied to quantitatively assess brain pathology in several diseases, especially multiple sclerosis (MS). To date, however, because of the high power deposition associated with the use of short, rapidly repeating MT prepulses, clinical application has been limited to lower field strengths. The contrast-to-noise ratio (CNR) of MT is limited, and this method would greatly benefit from the use of higher magnetic fields and phased-array coil reception. However, power deposition is proportional to the square of the magnetic field and scales with coil size, and MT experiments are already close to the SAR limit at 1.5T even when smaller transmit coils are used instead of the body coil. Here we show that these seemingly great obstacles can be ameliorated by the increased T(1) of tissue water at higher field, which allows for longer maintenance of sufficiently high saturation levels while using a reduced duty cycle. This enables a fast (5-6 min) high-resolution (1.5 mm isotropic) whole-brain MT acquisition with excellent anatomical visualization of gray matter (GM) and white matter (WM) structures, and even substructures. The method is demonstrated in nine normal volunteers and five patients with relapsing remitting MS (RRMS), and the results show a clear delineation of heterogeneous lesions.

  8. CHARACTERIZING TRANSFER OF SURFACE RESIDUES TO SKIN USING A VIDEO-FLUORESCENT IMAGING TECHNIQUE

    Science.gov (United States)

    Surface-to-skin transfer of contaminants is a complex process. For children's residential exposure, transfer of chemicals from contaminated surfaces such as floors and furniture is potentially significant. Once on the skin, residues and contaminated particles can be transferred b...

  9. Symmetric geometric transfer matrix partial volume correction for PET imaging: principle, validation and robustness

    Science.gov (United States)

    Sattarivand, Mike; Kusano, Maggie; Poon, Ian; Caldwell, Curtis

    2012-11-01

    Limited spatial resolution of positron emission tomography (PET) often requires partial volume correction (PVC) to improve the accuracy of quantitative PET studies. Conventional region-based PVC methods use co-registered high resolution anatomical images (e.g. computed tomography (CT) or magnetic resonance images) to identify regions of interest. Spill-over between regions is accounted for by calculating regional spread functions (RSFs) in a geometric transfer matrix (GTM) framework. This paper describes a new analytically derived symmetric GTM (sGTM) method that relies on spill-over between RSFs rather than between regions. It is shown that the sGTM is mathematically equivalent to Labbe's method; however it is a region-based method rather than a voxel-based method and it avoids handling large matrices. The sGTM method was validated using two three-dimensional (3D) digital phantoms and one physical phantom. A 3D digital sphere phantom with sphere diameters ranging from 5 to 30 mm and a sphere-to-background uptake ratio of 3-to-1 was used. A 3D digital brain phantom was used with four different anatomical regions and a background region with different activities assigned to each region. A physical sphere phantom with the same geometry and uptake as the digital sphere phantom was manufactured and PET-CT images were acquired. Using these three phantoms, the performance of the sGTM method was assessed against that of the GTM method in terms of accuracy, precision, noise propagation and robustness. The robustness was assessed by applying mis-registration errors and errors in estimates of PET point spread function (PSF). In all three phantoms, the results showed that the sGTM method has accuracy similar to that of the GTM method and within 5%. However, the sGTM method showed better precision and noise propagation than the GTM method, especially for spheres smaller than 13 mm. Moreover, the sGTM method was more robust than the GTM method when mis-registration errors or

  10. Symmetric geometric transfer matrix partial volume correction for PET imaging: principle, validation and robustness

    International Nuclear Information System (INIS)

    Sattarivand, Mike; Caldwell, Curtis; Kusano, Maggie; Poon, Ian

    2012-01-01

    Limited spatial resolution of positron emission tomography (PET) often requires partial volume correction (PVC) to improve the accuracy of quantitative PET studies. Conventional region-based PVC methods use co-registered high resolution anatomical images (e.g. computed tomography (CT) or magnetic resonance images) to identify regions of interest. Spill-over between regions is accounted for by calculating regional spread functions (RSFs) in a geometric transfer matrix (GTM) framework. This paper describes a new analytically derived symmetric GTM (sGTM) method that relies on spill-over between RSFs rather than between regions. It is shown that the sGTM is mathematically equivalent to Labbe's method; however it is a region-based method rather than a voxel-based method and it avoids handling large matrices. The sGTM method was validated using two three-dimensional (3D) digital phantoms and one physical phantom. A 3D digital sphere phantom with sphere diameters ranging from 5 to 30 mm and a sphere-to-background uptake ratio of 3-to-1 was used. A 3D digital brain phantom was used with four different anatomical regions and a background region with different activities assigned to each region. A physical sphere phantom with the same geometry and uptake as the digital sphere phantom was manufactured and PET-CT images were acquired. Using these three phantoms, the performance of the sGTM method was assessed against that of the GTM method in terms of accuracy, precision, noise propagation and robustness. The robustness was assessed by applying mis-registration errors and errors in estimates of PET point spread function (PSF). In all three phantoms, the results showed that the sGTM method has accuracy similar to that of the GTM method and within 5%. However, the sGTM method showed better precision and noise propagation than the GTM method, especially for spheres smaller than 13 mm. Moreover, the sGTM method was more robust than the GTM method when mis-registration errors or

  11. Imaging expression of adenoviral HSV1-tk suicide gene transfer using the nucleoside analogue FIRU

    International Nuclear Information System (INIS)

    Nanda, Dharmin; Jong, Marion de; Bakker, Willem; Bijster, Magda; Cox, Peter; Vogels, Ronald; Havenga, Menzo; Driesse, Maarten; Avezaat, Cees; Morin, Kevin; Naimi, Ebrahim; Knaus, Edward; Wiebe, Leonard; Smitt, Peter Sillevis

    2002-01-01

    Substrates for monitoring HSV1-tk gene expression include uracil and acycloguanosine derivatives.The most commonly used uracil derivative to monitor HSV1-tk gene transfer is 1-(2-fluoro-2-deoxy-β-D-arabinofuranosyl)-5-[*I]iodouracil (fialuridine; I*-FIAU), where the asterisk denotes any of the radioactive iodine isotopes that can be used. We have previously studied other nucleosides with imaging properties as good as or better than FIAU, including 1-(2-fluoro-2-deoxy-β-D-ribofuranosyl)-5-[*I]iodouracil (FIRU). The first aim of this study was to extend the biodistribution data of 123 I-labelled FIRU. Secondly, we assessed the feasibility of detecting differences in HSV1-tk gene expression levels following adenoviral gene transfer in vivo with 123 I-FIRU. 9L rat gliosarcoma cells were stably transfected with the HSV1-tk gene (9L-tk+). 123 I-FIRU was prepared by radioiodination of 1-(2-fluoro-2-deoxy-β-D-ribofuranosyl)-5-tributylstannyl uracil (FTMRSU; precursor compound) and purified using an activated Sep-Pak column. Incubation of 9L-tk+ cells and the parental 9L cells with 123 I-FIRU resulted in a 100-fold higher accumulation of radioactivity in the 9L-tk+ cells after an optimum incubation time of 4 h. NIH-bg-nu-xid mice were then inoculated subcutaneously with HSV1-tk (-) 9L cells or HSV1-tk (+) 9L-tk+ cells into both flanks. Biodistribution studies and gamma camera imaging were performed at 15 min and 1, 2, 4 and 24 h p.i. At 15 min, the tumour/muscle, tumour/blood and tumour/brain ratios were 5.2, 1.0 and 30.3 respectively. Rapid renal clearance of the tracer from the body resulted in increasing tumour/muscle, tumour/blood and tumour/brain ratios, reaching values of 32.2, 12.5 and 171.6 at 4 h p.i. A maximum specific activity of 22%ID/g tissue was reached in the 9L-tk+ tumours 4 h after 123 I-FIRU injection. Two Ad5-based adenoviral vectors containing the HSV1-tk gene were constructed: a replication-incompetent vector with the transgene in the former E1

  12. Imaging expression of adenoviral HSV1-tk suicide gene transfer using the nucleoside analogue FIRU

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Dharmin [Department of Neurology, Daniel den Hoed Cancer Centre, University Hospital Rotterdam (Netherlands); Department of Neurosurgery, University Hospital Rotterdam (Netherlands); Jong, Marion de; Bakker, Willem; Bijster, Magda; Cox, Peter [Department of Nuclear Medicine, University Hospital Rotterdam (Netherlands); Vogels, Ronald; Havenga, Menzo [Crucell Holland BV, Leiden (Netherlands); Driesse, Maarten; Avezaat, Cees [Department of Neurosurgery, University Hospital Rotterdam (Netherlands); Morin, Kevin; Naimi, Ebrahim; Knaus, Edward; Wiebe, Leonard [Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton (Canada); Smitt, Peter Sillevis [Department of Neurology, Daniel den Hoed Cancer Centre, University Hospital Rotterdam (Netherlands)

    2002-07-01

    Substrates for monitoring HSV1-tk gene expression include uracil and acycloguanosine derivatives.The most commonly used uracil derivative to monitor HSV1-tk gene transfer is 1-(2-fluoro-2-deoxy-{beta}-D-arabinofuranosyl)-5-[*I]iodouracil (fialuridine; I*-FIAU), where the asterisk denotes any of the radioactive iodine isotopes that can be used. We have previously studied other nucleosides with imaging properties as good as or better than FIAU, including 1-(2-fluoro-2-deoxy-{beta}-D-ribofuranosyl)-5-[*I]iodouracil (FIRU). The first aim of this study was to extend the biodistribution data of {sup 123}I-labelled FIRU. Secondly, we assessed the feasibility of detecting differences in HSV1-tk gene expression levels following adenoviral gene transfer in vivo with {sup 123}I-FIRU. 9L rat gliosarcoma cells were stably transfected with the HSV1-tk gene (9L-tk+). {sup 123}I-FIRU was prepared by radioiodination of 1-(2-fluoro-2-deoxy-{beta}-D-ribofuranosyl)-5-tributylstannyl uracil (FTMRSU; precursor compound) and purified using an activated Sep-Pak column. Incubation of 9L-tk+ cells and the parental 9L cells with {sup 123}I-FIRU resulted in a 100-fold higher accumulation of radioactivity in the 9L-tk+ cells after an optimum incubation time of 4 h. NIH-bg-nu-xid mice were then inoculated subcutaneously with HSV1-tk (-) 9L cells or HSV1-tk (+) 9L-tk+ cells into both flanks. Biodistribution studies and gamma camera imaging were performed at 15 min and 1, 2, 4 and 24 h p.i. At 15 min, the tumour/muscle, tumour/blood and tumour/brain ratios were 5.2, 1.0 and 30.3 respectively. Rapid renal clearance of the tracer from the body resulted in increasing tumour/muscle, tumour/blood and tumour/brain ratios, reaching values of 32.2, 12.5 and 171.6 at 4 h p.i. A maximum specific activity of 22%ID/g tissue was reached in the 9L-tk+ tumours 4 h after {sup 123}I-FIRU injection. Two Ad5-based adenoviral vectors containing the HSV1-tk gene were constructed: a replication-incompetent vector with

  13. Optimization of selective inversion recovery magnetization transfer imaging for macromolecular content mapping in the human brain.

    Science.gov (United States)

    Dortch, Richard D; Bagnato, Francesca; Gochberg, Daniel F; Gore, John C; Smith, Seth A

    2018-03-24

    To optimize a selective inversion recovery (SIR) sequence for macromolecular content mapping in the human brain at 3.0T. SIR is a quantitative method for measuring magnetization transfer (qMT) that uses a low-power, on-resonance inversion pulse. This results in a biexponential recovery of free water signal that can be sampled at various inversion/predelay times (t I/ t D ) to estimate a subset of qMT parameters, including the macromolecular-to-free pool-size-ratio (PSR), the R 1 of free water (R 1f ), and the rate of MT exchange (k mf ). The adoption of SIR has been limited by long acquisition times (≈4 min/slice). Here, we use Cramér-Rao lower bound theory and data reduction strategies to select optimal t I /t D combinations to reduce imaging times. The schemes were experimentally validated in phantoms, and tested in healthy volunteers (N = 4) and a multiple sclerosis patient. Two optimal sampling schemes were determined: (i) a 5-point scheme (k mf estimated) and (ii) a 4-point scheme (k mf assumed). In phantoms, the 5/4-point schemes yielded parameter estimates with similar SNRs as our previous 16-point scheme, but with 4.1/6.1-fold shorter scan times. Pair-wise comparisons between schemes did not detect significant differences for any scheme/parameter. In humans, parameter values were consistent with published values, and similar levels of precision were obtained from all schemes. Furthermore, fixing k mf reduced the sensitivity of PSR to partial-volume averaging, yielding more consistent estimates throughout the brain. qMT parameters can be robustly estimated in ≤1 min/slice (without independent measures of ΔB 0 , B1+, and T 1 ) when optimized t I -t D combinations are selected. © 2018 International Society for Magnetic Resonance in Medicine.

  14. Do basic psychomotor skills transfer between different image-based procedures?

    Science.gov (United States)

    Buzink, Sonja N; Goossens, Richard H M; Schoon, Erik J; de Ridder, Huib; Jakimowicz, Jack J

    2010-05-01

    Surgical techniques that draw from multiple types of image-based procedures (IBP) are increasing, such as Natural Orifice Transluminal Endoscopic Surgery, fusing laparoscopy and flexible endoscopy. However, little is known about the relation between psychomotor skills for performing different types of IBP. For example, do basic psychomotor colonoscopy and laparoscopy skills interact? Following a cross-over study design, 29 naïve endoscopists were trained on the Simbionix GI Mentor and the SimSurgery SEP simulators. Group C (n = 15) commenced with a laparoscopy session, followed by four colonoscopy sessions and a second laparoscopy session. Group L (n = 14) started with a colonoscopy session, followed by four laparoscopy sessions and a second colonoscopy session. No significant differences were found between the performances of group L and group C in their first training sessions on either technique. With additional colonoscopy training, group C outperformed group L in the second laparoscopy training session on the camera navigation task. Overall, training in the basic colonoscopy tasks does not affect performance of basic laparoscopy tasks (and vice versa). However, to limited extent, training of basic psychomotor skills for colonoscopy do appear to contribute to the performance of angled laparoscope navigation tasks. Thus, training and assessment of IBP type-specific skills should focus on each type of tasks independently. Future research should further investigate the influence of psychometric abilities on the performance of IBP and the transfer of skills for physicians who are experienced in one IBP type and would like to become proficient in another type of IBP.

  15. Cascade Convolutional Neural Network Based on Transfer-Learning for Aircraft Detection on High-Resolution Remote Sensing Images

    Directory of Open Access Journals (Sweden)

    Bin Pan

    2017-01-01

    Full Text Available Aircraft detection from high-resolution remote sensing images is important for civil and military applications. Recently, detection methods based on deep learning have rapidly advanced. However, they require numerous samples to train the detection model and cannot be directly used to efficiently handle large-area remote sensing images. A weakly supervised learning method (WSLM can detect a target with few samples. However, it cannot extract an adequate number of features, and the detection accuracy requires improvement. We propose a cascade convolutional neural network (CCNN framework based on transfer-learning and geometric feature constraints (GFC for aircraft detection. It achieves high accuracy and efficient detection with relatively few samples. A high-accuracy detection model is first obtained using transfer-learning to fine-tune pretrained models with few samples. Then, a GFC region proposal filtering method improves detection efficiency. The CCNN framework completes the aircraft detection for large-area remote sensing images. The framework first-level network is an image classifier, which filters the entire image, excluding most areas with no aircraft. The second-level network is an object detector, which rapidly detects aircraft from the first-level network output. Compared with WSLM, detection accuracy increased by 3.66%, false detection decreased by 64%, and missed detection decreased by 23.1%.

  16. Pocket Size Solid State FLASH and iPOD Drives for gigabyte storage, display and transfer of digital medical images: an introduction

    International Nuclear Information System (INIS)

    Sankaran, A.

    2008-01-01

    The transition of radiological imaging from analog to digital was closely followed by the development of the Picture Archiving and Communication (PACS) system. Concomitantly, multidimensional imaging ( 4D and 5D, for motion and functional studies on 3D images) have presented new challenges, particularly in handling gigabyte size images from CT, MRI and PET scanners, which generate thousands of images. The storage and analysis of these images necessitate expensive image workstations. This paper highlights the recent innovations in mass storage, display and transfer of images, using miniature/pocket size solid state FLASH and iPOD drives

  17. Pore-scale study on flow and heat transfer in 3D reconstructed porous media using micro-tomography images

    International Nuclear Information System (INIS)

    Liu, Zhenyu; Wu, Huiying

    2016-01-01

    Highlights: • The complex porous domain has been reconstructed with the micro CT scan images. • Pore-scale numerical model based on LB method has been established. • The correlations for flow and heat transfer were derived from the predictions. • The numerical approach developed in this work is suitable for complex porous media. - Abstract: This paper presents the numerical study on fluid flow and heat transfer in reconstructed porous media at the pore-scale with the double-population thermal lattice Boltzmann (LB) method. The porous geometry was reconstructed using micro-tomography images from micro-CT scanner. The thermal LB model was numerically tested before simulation and a good agreement was achieved by compared with the existing results. The detailed distributions of velocity and temperature in complex pore spaces were obtained from the pore-scale simulation. The correlations for flow and heat transfer in the specific porous media sample were derived based on the numerical results. The numerical method established in this work provides a promising approach to predict pore-scale flow and heat transfer characteristics in reconstructed porous domain with real geometrical effect, which can be extended for the continuum modeling of the transport process in porous media at macro-scale.

  18. Technique for improving the quality of images from digital cameras using ink-jet printers and smoothed RGB transfer curves

    Science.gov (United States)

    Sampat, Nitin; Grim, John F.; O'Hara, James E.

    1998-04-01

    The digital camera market is growing at an explosive rate. At the same time, the quality of photographs printed on ink- jet printers continues to improve. Most of the consumer cameras are designed with the monitor as the target output device and ont the printer. When a user is printing his images from a camera, he/she needs to optimize the camera and printer combination in order to maximize image quality. We describe the details of one such method for improving image quality using a AGFA digital camera and an ink jet printer combination. Using Adobe PhotoShop, we generated optimum red, green and blue transfer curves that match the scene content to the printers output capabilities. Application of these curves to the original digital image resulted in a print with more shadow detail, no loss of highlight detail, a smoother tone scale, and more saturated colors. The image also exhibited an improved tonal scale and visually more pleasing images than those captured and printed without any 'correction'. While we report the results for one camera-printer combination we tested this technique on numbers digital cameras and printer combinations and in each case produced a better looking image. We also discuss the problems we encountered in implementing this technique.

  19. Image-Based Modeling of Blood Flow and Oxygen Transfer in Feto-Placental Capillaries.

    Directory of Open Access Journals (Sweden)

    Philip Pearce

    Full Text Available During pregnancy, oxygen diffuses from maternal to fetal blood through villous trees in the placenta. In this paper, we simulate blood flow and oxygen transfer in feto-placental capillaries by converting three-dimensional representations of villous and capillary surfaces, reconstructed from confocal laser scanning microscopy, to finite-element meshes, and calculating values of vascular flow resistance and total oxygen transfer. The relationship between the total oxygen transfer rate and the pressure drop through the capillary is shown to be captured across a wide range of pressure drops by physical scaling laws and an upper bound on the oxygen transfer rate. A regression equation is introduced that can be used to estimate the oxygen transfer in a capillary using the vascular resistance. Two techniques for quantifying the effects of statistical variability, experimental uncertainty and pathological placental structure on the calculated properties are then introduced. First, scaling arguments are used to quantify the sensitivity of the model to uncertainties in the geometry and the parameters. Second, the effects of localized dilations in fetal capillaries are investigated using an idealized axisymmetric model, to quantify the possible effect of pathological placental structure on oxygen transfer. The model predicts how, for a fixed pressure drop through a capillary, oxygen transfer is maximized by an optimal width of the dilation. The results could explain the prevalence of fetal hypoxia in cases of delayed villous maturation, a pathology characterized by a lack of the vasculo-syncytial membranes often seen in conjunction with localized capillary dilations.

  20. In Vivo Imaging of Tissue Physiological Function using EPR Spectroscopy | NCI Technology Transfer Center | TTC

    Science.gov (United States)

    Electron paramagnetic resonance (EPR) is a technique for studying chemical species that have one or more unpaired electrons.  The current invention describes Echo-based Single Point Imaging (ESPI), a novel EPR image formation strategy that allows in vivo imaging of physiological function.  The National Cancer Institute's Radiation Biology Branch is seeking statements of capability or interest from parties interested in in-licensing an in vivo imaging using Electron paramagnetic resonance (EPR) to measure active oxygen species.

  1. Time-resolved imaging of flyer dynamics for femtosecond laser-induced backward transfer of solid polymer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Feinaeugle, M., E-mail: m.feinaeugle@utwente.nl [Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Gregorčič, P. [Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000, Ljubljana (Slovenia); Heath, D.J. [Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Mills, B., E-mail: bm602@orc.soton.ac.uk [Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Eason, R.W. [Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

    2017-02-28

    Highlights: • Laser-induced backward transfer was investigated by time-resolved shadowgraphy. • Flyer velocity was a function of carrier, donor thickness, delay and fluence. • We investigated the fluence window for intact transfer and the role of the receiver. • Donor-crater profile variation was studied for different ejection regimes. • Conditions for intact and fragmented flyers were determined. - Abstract: We have studied the transfer regimes and dynamics of polymer flyers from laser-induced backward transfer (LIBT) via time-resolved shadowgraphy. Imaging of the flyer ejection phase of LIBT of 3.8 μm and 6.4 μm thick SU-8 polymer films on germanium and silicon carrier substrates was performed over a time delay range of 1.4–16.4 μs after arrival of the laser pulse. The experiments were carried out with 150 fs, 800 nm pulses spatially shaped using a digital micromirror device, and laser fluences of up to 3.5 J/cm{sup 2} while images were recorded via a CCD camera and a spark discharge lamp. Velocities of flyers found in the range of 6–20 m/s, and the intact and fragmented ejection regimes, were a function of donor thickness, carrier and laser fluence. The crater profile of the donor after transfer and the resulting flyer profile indicated different flyer ejection modes for Si carriers and high fluences. The results contribute to better understanding of the LIBT process, and help to determine experimental parameters for successful LIBT of intact deposits.

  2. Brain MR post-gadolinium contrast in multiple sclerosis: the role of magnetization transfer and image subtraction in detecting more enhancing lesions

    Energy Technology Data Exchange (ETDEWEB)

    Gavra, M.M.; Gouliamos, A.D.; Vlahos, L.J. [Department of Radiology, ' ' Aretaieion' ' Hospital,University of Athens Medical School, Athens (Greece); Voumvourakis, C.; Sfagos, C. [Department of Neurology, ' ' Eginiteion' ' Hospital, University of Athens Medical School, Athens (Greece)

    2004-03-01

    Our purpose was to evaluate the role of magnetization transfer and image subtraction in detecting more enhancing lesions in brain MR imaging of patients with multiple sclerosis (MS). Thirty-one MS patients underwent MR imaging of the brain with T1-weighted spin echo sequences without and with magnetization transfer (MT) using a 1.5 T imager. Both sequences were acquired before and after intravenous injection of a paramagnetic contrast agent. Subtraction images in T1-weighted sequences were obtained by subtracting the pre-contrast images from the post-contrast ones. A significant difference was found between the numbers of enhanced areas in post-gadolinium T1-weighted images without and with MT (p=0.020). The post-gadolinium T1-weighted images with MT allowed the detection of an increased (13) number of enhancing lesions compared with post-gadolinium T1-weighted images without MT. A significant difference was also found between the numbers of enhanced areas in post-gadolinium T1-weighted images without MT and subtraction images without MT (p=0.020). The subtraction images without MT allowed the detection of an increased (10) number of enhancing lesions compared with post-gadolinium T1-weighted images without MT. Magnetization transfer contrast and subtraction techniques appear to be the simplest and least time-consuming applications to improve the conspicuity and detection of contrast-enhancing lesions in patients with MS. (orig.)

  3. Brain MR post-gadolinium contrast in multiple sclerosis: the role of magnetization transfer and image subtraction in detecting more enhancing lesions

    International Nuclear Information System (INIS)

    Gavra, M.M.; Gouliamos, A.D.; Vlahos, L.J.; Voumvourakis, C.; Sfagos, C.

    2004-01-01

    Our purpose was to evaluate the role of magnetization transfer and image subtraction in detecting more enhancing lesions in brain MR imaging of patients with multiple sclerosis (MS). Thirty-one MS patients underwent MR imaging of the brain with T1-weighted spin echo sequences without and with magnetization transfer (MT) using a 1.5 T imager. Both sequences were acquired before and after intravenous injection of a paramagnetic contrast agent. Subtraction images in T1-weighted sequences were obtained by subtracting the pre-contrast images from the post-contrast ones. A significant difference was found between the numbers of enhanced areas in post-gadolinium T1-weighted images without and with MT (p=0.020). The post-gadolinium T1-weighted images with MT allowed the detection of an increased (13) number of enhancing lesions compared with post-gadolinium T1-weighted images without MT. A significant difference was also found between the numbers of enhanced areas in post-gadolinium T1-weighted images without MT and subtraction images without MT (p=0.020). The subtraction images without MT allowed the detection of an increased (10) number of enhancing lesions compared with post-gadolinium T1-weighted images without MT. Magnetization transfer contrast and subtraction techniques appear to be the simplest and least time-consuming applications to improve the conspicuity and detection of contrast-enhancing lesions in patients with MS. (orig.)

  4. Towards an ultra-thin medical endoscope: multimode fibre as a wide-field image transferring medium

    Science.gov (United States)

    Duriš, Miroslav; Bradu, Adrian; Podoleanu, Adrian; Hughes, Michael

    2018-03-01

    Multimode optical fibres are attractive for biomedical and industrial applications such as endoscopes because of the small cross section and imaging resolution they can provide in comparison to widely-used fibre bundles. However, the image is randomly scrambled by propagation through a multimode fibre. Even though the scrambling is unpredictable, it is deterministic, and therefore the scrambling can be reversed. To unscramble the image, we treat the multimode fibre as a linear, disordered scattering medium. To calibrate, we scan a focused beam of coherent light over thousands of different beam positions at the distal end and record complex fields at the proximal end of the fibre. This way, the inputoutput response of the system is determined, which then allows computational reconstruction of reflection-mode images. However, there remains the problem of illuminating the tissue via the fibre while avoiding back reflections from the proximal face. To avoid this drawback, we provide here the first preliminary confirmation that an image can be transferred through a 2x2 fibre coupler, with the sample at its distal port interrogated in reflection. Light is injected into one port for illumination and then collected from a second port for imaging.

  5. The Assessment of Structural Changes in MS Plaques and Normal Appearing White Matter Using Quantitative Magnetization Transfer Imaging (MTI

    Directory of Open Access Journals (Sweden)

    Masoomeh Fooladi

    2007-12-01

    Full Text Available Introduction: Multiple sclerosis (MS is a demyelinating disease of the central nervous system (CNS, affecting mostly young people at a mean age of 30 years. Magnetic resonance imaging (MRI is one of the most specific and sensitive methods in diagnosing and detecting the evolution of multiple sclerosis disease. But it does not have the ability to differentiate between distinct histopathological heterogeneities that occur in MS lesions and brain tissue.Quantitative magnetization transfer imaging (qMTI is a relatively new MRI technique which can be used to examine the pathological processes of the brain parenchyma which occur in MS patients.This quantitative MRI technique can provide more complete information about the extent and nature of the brain tissue destruction in multiple sclerosis, which cannot be detected by conventional MRI. Material and Methods: In this study, twelve patients with relapsing-remitting MS and twelve healthy control subjects underwent conventional MR imaging including: T2-FSE, T1-SE and FLAIR sequences as well as quantitative magnetization transfer imaging. All the focal lesions were identified on T2-weighted images and were classified according to their signal hypointensity on T1-weighted scans. The white matter and MS lesions were segmented using a semi-automated system. MT ratio (MTR histogram analysis was performed for the brain white matter and the average MTR value was calculated for the classified MS lesions. Results: A significant reduction was found in MTR value of the normal appearing white matter (NAWM in patients with relapsing-remitting MS, suggesting that MS is a more diffuse disease, affecting the whole brain tissue. A wide range changes in MTR values can be observed in MS lesions. MTR reduction is correlated with the degree of lesion hypointensity on T1-weighted scans. The lower MTR values of lesions that appear progressively more hypointense on T1-weigted images reflect varying degrees of demyelination and

  6. On-bead combinatorial synthesis and imaging of chemical exchange saturation transfer magnetic resonance imaging agents to identify factors that influence water exchange.

    Science.gov (United States)

    Napolitano, Roberta; Soesbe, Todd C; De León-Rodríguez, Luis M; Sherry, A Dean; Udugamasooriya, D Gomika

    2011-08-24

    The sensitivity of magnetic resonance imaging (MRI) contrast agents is highly dependent on the rate of water exchange between the inner sphere of a paramagnetic ion and bulk water. Normally, identifying a paramagnetic complex that has optimal water exchange kinetics is done by synthesizing and testing one compound at a time. We report here a rapid, economical on-bead combinatorial synthesis of a library of imaging agents. Eighty different 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid (DOTA)-tetraamide peptoid derivatives were prepared on beads using a variety of charged, uncharged but polar, hydrophobic, and variably sized primary amines. A single chemical exchange saturation transfer image of the on-bead library easily distinguished those compounds having the most favorable water exchange kinetics. This combinatorial approach will allow rapid screening of libraries of imaging agents to identify the chemical characteristics of a ligand that yield the most sensitive imaging agents. This technique could be automated and readily adapted to other types of MRI or magnetic resonance/positron emission tomography agents as well.

  7. A theory of frequency domain invariants: spherical harmonic identities for BRDF/lighting transfer and image consistency.

    Science.gov (United States)

    Mahajan, Dhruv; Ramamoorthi, Ravi; Curless, Brian

    2008-02-01

    This paper develops a theory of frequency domain invariants in computer vision. We derive novel identities using spherical harmonics, which are the angular frequency domain analog to common spatial domain invariants such as reflectance ratios. These invariants are derived from the spherical harmonic convolution framework for reflection from a curved surface. Our identities apply in a number of canonical cases, including single and multiple images of objects under the same and different lighting conditions. One important case we consider is two different glossy objects in two different lighting environments. For this case, we derive a novel identity, independent of the specific lighting configurations or BRDFs, that allows us to directly estimate the fourth image if the other three are available. The identity can also be used as an invariant to detecttampering in the images. While this paper is primarily theoretical, it has the potential to lay the mathematical foundations for two important practical applications. First, we can develop more general algorithms for inverse rendering problems, which can directly relight and change material properties by transferring the BRDF or lighting from another object or illumination. Second, we can check the consistency of an image, to detect tampering or image splicing.

  8. Nuclear Overhauser Enhancement imaging of glioblastoma at 7 Tesla: region specific correlation with apparent diffusion coefficient and histology.

    Science.gov (United States)

    Paech, Daniel; Burth, Sina; Windschuh, Johannes; Meissner, Jan-Eric; Zaiss, Moritz; Eidel, Oliver; Kickingereder, Philipp; Nowosielski, Martha; Wiestler, Benedikt; Sahm, Felix; Floca, Ralf Omar; Neumann, Jan-Oliver; Wick, Wolfgang; Heiland, Sabine; Bendszus, Martin; Schlemmer, Heinz-Peter; Ladd, Mark Edward; Bachert, Peter; Radbruch, Alexander

    2015-01-01

    To explore the correlation between Nuclear Overhauser Enhancement (NOE)-mediated signals and tumor cellularity in glioblastoma utilizing the apparent diffusion coefficient (ADC) and cell density from histologic specimens. NOE is one type of chemical exchange saturation transfer (CEST) that originates from mobile macromolecules such as proteins and might be associated with tumor cellularity via altered protein synthesis in proliferating cells. For 15 patients with newly diagnosed glioblastoma, NOE-mediated CEST-contrast was acquired at 7 Tesla (asymmetric magnetization transfer ratio (MTRasym) at 3.3ppm, B1 = 0.7 μT). Contrast enhanced T1 (CE-T1), T2 and diffusion-weighted MRI (DWI) were acquired at 3 Tesla and coregistered. The T2 edema and the CE-T1 tumor were segmented. ADC and MTRasym values within both regions of interest were correlated voxelwise yielding the correlation coefficient rSpearman (rSp). In three patients who underwent stereotactic biopsy, cell density of 12 specimens per patient was correlated with corresponding MTRasym and ADC values of the biopsy site. Eight of 15 patients showed a weak or moderate positive correlation of MTRasym and ADC within the T2 edema (0.16≤rSp≤0.53, pcorrelations were statistically insignificant (p>0.05, n = 4) or yielded rSp≈0 (pcorrelation between MTRasym and ADC was found in CE-T1 tumor (-0.310.05, n = 6). The biopsy-analysis within CE-T1 tumor revealed a strong positive correlation between tumor cellularity and MTRasym values in two of the three patients (rSppatient3 = 0.69 and rSppatient15 = 0.87, pcorrelation of ADC and cellularity was heterogeneous (rSppatient3 = 0.545 (p = 0.067), rSppatient4 = -0.021 (p = 0.948), rSppatient15 = -0.755 (p = 0.005)). NOE-imaging is a new contrast promising insight into pathophysiologic processes in glioblastoma regarding cell density and protein content, setting itself apart from DWI. Future studies might be based on the assumption that NOE-mediated CEST visualizes

  9. Pathological Assessment of Brain White Matter in Relapsing-Remitting MS Patients using Quantitative Magnetization Transfer Imaging

    Directory of Open Access Journals (Sweden)

    Khodarahm Pahlevan

    2011-09-01

    Full Text Available Introduction: Multiple sclerosis (MS is characterized by lesions in the white matter (WM of the central nervous system. Magnetic resonance imaging is the most specific and sensitive method for diagnosis of multiple sclerosis. However, the ability of conventional MRI to show histopathologic heterogeneity of MS lesions is insufficient. Quantitative magnetization transfer imaging (qMTI is a relatively new method to investigate pathologic processes of the brain tissue occurring in MS patients. Material and Methods: Voxel-based analyses allow regional comparisons between groups to be made for the whole brain in a single analysis. This is done by coregistering data from all individual subjects to a reference brain, generally referred to as the "standard space", and then comparing them on a voxel-by-voxel basis. This study aimed to analyze whole-brain quantitative T1 maps, not to find global changes or changes in selected regions, but specifically to investigate the spatial distribution throughout the brain of T1 increases in MS WM with respect to control WM. In this study, 11 healthy controls, 10 relapsing-remitting (RR MS patients and 13 CIS patients were studied using MT-MRI imaging. MT parameters, including magnetization transfer ratio (MTR, magnetization transfer rate between free protons and restricted macromolecular protons, Ksat and longitudinal relaxation times (with and without MT saturation pulse, T1sat and T1free values were evaluated. Results: The results showed that, at a group level, there is widespread involvement of WM throughout the brain in CIS MS and especially in RRMS, where a significant T1 increase was found in 15.58% of WM voxels (normals < RR. Discussion and Conclusion: This study demonstrates that WM in large parts of the brain is susceptible to disease processes in RR and CIS MS

  10. Taking up an event: Brand image transfer during the FIFA World Cup

    NARCIS (Netherlands)

    Neijens, P.; Smit, E.; Moorman, M.

    2009-01-01

    A real-life study (N = 1299) into brand images during and after the 2006 FIFA World Cup football tournament showed that the event was a good platform for the creation of brand images through ‘take-up’ advertising in which the brand was associated with the event. Exposure level and involvement with

  11. 31P saturation transfer and phosphocreatine imaging in the monkey brain

    International Nuclear Information System (INIS)

    Mora, B.; Narasimhan, P.T.; Ross, B.D.; Allman, J.; Barker, P.B.

    1991-01-01

    31 P magnetic resonance imaging with chemical-shift discrimination by selective excitation has been employed to determine the phosphocreatine (PCr) distribution in the brains of three juvenile macaque monkeys. PCr images were also obtained while saturating the resonance of the γ-phosphate of ATP, which allowed the investigation of the chemical exchange between PCr and the γ-phosphate of ATP catalyzed by creatine kinase. Superposition of the PCr images over the proton image of the same monkey brain revealed topological variations in the distribution of PCr and creatine kinase activity. PCr images were also obtained with and without visual stimulation. In two out of four experiments, an apparently localized decrease in PCr concentration was noted in visual cortex upon visual stimulation. This result is interpreted in terms of a possible role for the local ADP concentration in stimulating the accompanying metabolic response

  12. Passion simple and Madame, c'est à vous que j'écris: "That's MY Desire"

    Directory of Open Access Journals (Sweden)

    Elizabeth Richardson Viti

    2001-06-01

    Full Text Available No two texts better exemplify the contemporary "he said, she said" phenomenon than Annie Ernaux's Passion simple and Alain Gérard's Madame, c'est à vous que j'écris . Ernaux's book, published in 1991, recounts the author's heretofore hidden affair with a foreign businessman living temporarily in France, and Gérard's, published four years later, is an explicit response in which the writer, dissatisfied with Ernaux's account, assumes the lover's identity and chronicles events from his perspective. The result is a literary "tac à tac" very much in the public eye in which a man and woman both wish to tell their side of the story about a past sexual relationship. For her part, Ernaux gives primacy to woman as sexual subject and describes an erotic economy where the lover is nothing more than simple support for the female imaginary. Gérard responds to Ernaux's reduction of the lover to pure sex object by reestablishing his primacy as well as that of the phallus, around which desire has traditionally revolved. Indeed, what is most intriguing about this unusual pair is their disagreement over the definition of desire, and thus, how they illustrate the fundamental feminist notion that gender informs writing as well as reading.

  13. Introduction of image analysis for the quantification of the boiling flow heat transfer

    NARCIS (Netherlands)

    Ferret, C.; Falk, L.; d'Ortona, U.; Chenu, A.; Veenstra, T.T.

    2004-01-01

    Heat transfer performances for non-boiling and boiling flow of a micro-vaporizer have been measured by standard methods (temperatures, flow rates, effective power input). The study was carried out for laminar flow (Re<25) in silicon micro-channels (5 mm×3 cm×200 μm) filled with ordered obstacles to

  14. Image-Based Modeling of Blood Flow and Oxygen Transfer in Feto-Placental Capillaries

    Czech Academy of Sciences Publication Activity Database

    Pearce, P.; Brownbill, P.; Janáček, Jiří; Jirkovská, M.; Kubínová, Lucie; Chernyavsky, I. L.; Jensen, O. E.

    2016-01-01

    Roč. 11, č. 10 (2016), č. článku e0165369. E-ISSN 1932-6203 Institutional support: RVO:67985823 Keywords : placenta * capillaries * oxygen transfer * confocal microscopy Subject RIV: EA - Cell Biology Impact factor: 2.806, year: 2016

  15. DERMAL AND MOUTHING TRANSFERS OF SURFACE RESIDUES MEASURED USING FLUORESCENCE IMAGING

    Science.gov (United States)

    To reduce the uncertainty associated with current estimates of children's exposure to pesticides by dermal contact and non-dietary ingestion, residue transfer data are required. Prior to conducting exhaustive studies, a screening study to develop and test methods for measuring...

  16. PET/CT (and CT) instrumentation, image reconstruction and data transfer for radiotherapy planning

    DEFF Research Database (Denmark)

    Sattler, Bernhard; Lee, John A; Lonsdale, Markus

    2010-01-01

    -invasive imaging technique, offers the visualization and quantification of pre-selected tracer metabolism. In combination with the structural information from CT, this molecular imaging technique has great potential to support and improve the outcome of the treatment-planning procedure prior to radiotherapy......, the DICOM-Standard provides objects and classes for this purpose (DICOM RT). Furthermore, the standard DICOM objects and classes for nuclear medicine (NM, PT) and computed tomography (CT) are used to communicate the actual image data created by the modalities. Care must be taken for data security...

  17. Do Basic Psychomotor Skills Transfer Between Different Image-based Procedures?

    NARCIS (Netherlands)

    Buzink, S.N.; Goossens, R.H.M.; Schoon, E.J.; De Ridder, H.; Jakimowicz, J.J.

    2010-01-01

    Background - Surgical techniques that draw from multiple types of image-based procedures (IBP) are increasing, such as Natural Orifice Transluminal Endoscopic Surgery, fusing laparoscopy and flexible endoscopy. However, little is known about the relation between psychomotor skills for performing

  18. Image Reconstruction for Diffuse Optical Tomography Based on Radiative Transfer Equation

    Directory of Open Access Journals (Sweden)

    Bo Bi

    2015-01-01

    L2 regularization. Results also show the competitive performance of the split Bregman algorithm for the DOT image reconstruction with sparsity regularization compared with other existing L1 algorithms.

  19. Emerging from Water: Underwater Image Color Correction Based on Weakly Supervised Color Transfer

    OpenAIRE

    Li, Chongyi; Guo, Jichang; Guo, Chunle

    2017-01-01

    Underwater vision suffers from severe effects due to selective attenuation and scattering when light propagates through water. Such degradation not only affects the quality of underwater images but limits the ability of vision tasks. Different from existing methods which either ignore the wavelength dependency of the attenuation or assume a specific spectral profile, we tackle color distortion problem of underwater image from a new view. In this letter, we propose a weakly supervised color tr...

  20. Noninvasive imaging of protein-protein interactions from live cells and living subjects using bioluminescence resonance energy transfer.

    Science.gov (United States)

    De, Abhijit; Gambhir, Sanjiv Sam

    2005-12-01

    This study demonstrates a significant advancement of imaging of a distance-dependent physical process, known as the bioluminescent resonance energy transfer (BRET2) signal in living subjects, by using a cooled charge-coupled device (CCD) camera. A CCD camera-based spectral imaging strategy enables simultaneous visualization and quantitation of BRET signal from live cells and cells implanted in living mice. We used the BRET2 system, which utilizes Renilla luciferase (hRluc) protein and its substrate DeepBlueC (DBC) as an energy donor and a mutant green fluorescent protein (GFP2) as the acceptor. To accomplish this objective in this proof-of-principle study, the donor and acceptor proteins were fused to FKBP12 and FRB, respectively, which are known to interact only in the presence of the small molecule mediator rapamycin. Mammalian cells expressing these fusion constructs were imaged using a cooled-CCD camera either directly from culture dishes or by implanting them into mice. By comparing the emission photon yields in the presence and absence of rapamycin, the specific BRET signal was determined. The CCD imaging approach of BRET signal is particularly appealing due to its capacity to seamlessly bridge the gap between in vitro and in vivo studies. This work validates BRET as a powerful tool for interrogating and observing protein-protein interactions directly at limited depths in living mice.

  1. Performance of asynchronous transfer mode (ATM) local area and wide area networks for medical imaging transmission in clinical environment.

    Science.gov (United States)

    Huang, H K; Wong, A W; Zhu, X

    1997-01-01

    Asynchronous transfer mode (ATM) technology emerges as a leading candidate for medical image transmission in both local area network (LAN) and wide area network (WAN) applications. This paper describes the performance of an ATM LAN and WAN network at the University of California, San Francisco. The measurements were obtained using an intensive care unit (ICU) server connecting to four image workstations (WS) at four different locations of a hospital-integrated picture archiving and communication system (HI-PACS) in a daily regular clinical environment. Four types of performance were evaluated: magnetic disk-to-disk, disk-to-redundant array of inexpensive disks (RAID), RAID-to-memory, and memory-to-memory. Results demonstrate that the transmission rate between two workstations can reach 5-6 Mbytes/s from RAID-to-memory, and 8-10 Mbytes/s from memory-to-memory. When the server has to send images to all four workstations simultaneously, the transmission rate to each WS is about 4 Mbytes/s. Both situations are adequate for radiologic image communications for picture archiving and communication systems (PACS) and teleradiology applications.

  2. TH-C-17A-02: New Radioluminescence Strategies Based On CRET (Cerenkov Radiation Energy Transfer) for Imaging and Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Volotskova, O; Sun, C; Pratx, G; Xing, L [Stanford University, Stanford, CA (United States)

    2014-06-15

    Purpose: Cerenkov photons are produced when charged particles, emitted from radionuclides, travel through a media with a speed greater than that of the light in the media. Cerenkov radiation is mostly in the UV/Blue region and, thus, readily absorbed by biological tissue. Cerenkov Radiation Energy Transfer (CRET) is a wavelength-shifting phenomenon from blue Cerenkov light to more penetrating red wavelengths. We demonstrate the feasibility of in-depth imaging of CRET light originating from radionuclides realized by down conversion of gold nanoclusters (AuNCs, a novel particle composed of few atoms of gold coated with serum proteins) in vivo. Methods: Bovine Serum Albumin, Human Serum Albumin and Transferrin conjugated gold nanoclusters were synthesized, characterized and examined for CRET. Three different clinically used radiotracers: 18F-FDG, 90Y and 99mTc were used. Optical spectrum (440–750 nm) was recorded by sensitive bioluminescence imaging system at physiological temperature. Dose dependence (activity range from 0.5 up to 800uCi) and concentration dependence (0.01 to 1uM) studies were carried out. The compound was also imaged in a xenograft mouse model. Results: Only β+ and β--emitting radionuclides (18F-FDG, 90Y) are capable of CRET; no signal was found in 99mTc (γ-emitter). The emission peak of CRET by AuNCs was found to be ∼700 nm and was ∼3 fold times of background. In vitro studies showed a linear dependency between luminescence intensity and dose and concentration. CRET by gold nanoclusters was observed in xenografted mice injected with 100uCi of 18F-FDG. Conclusion: The unique optical, transport and chemical properties of AuNCs (gold nanoclusters) make them ideal candidates for in-vivo imaging applications. Development of new molecular imaging probes will allow us to achieve substantially improved spatiotemporal resolution, sensitivity and specificity for tumor imaging and detection.

  3. Synthesis and systematic evaluation of dark resonance energy transfer (DRET)-based library and its application in cell imaging.

    Science.gov (United States)

    Su, Dongdong; Teoh, Chai Lean; Kang, Nam-Young; Yu, Xiaotong; Sahu, Srikanta; Chang, Young-Tae

    2015-03-01

    In this paper, we report a new strategy for constructing a dye library with large Stokes shifts. By coupling a dark donor with BODIPY acceptors of tunable high quantum yield, a novel dark resonance energy transfer (DRET)-based library, named BNM, has been synthesized. Upon excitation of the dark donor (BDN) at 490 nm, the absorbed energy is transferred to the acceptor (BDM) with high efficiency, which was tunable in a broad range from 557 nm to 716 nm, with a high quantum yield of up to 0.8. It is noteworthy to mention that the majority of the non-radiative energy loss of the donor was converted into the acceptor's fluorescence output with a minimum leak of donor emission. Fluorescence imaging tested in live cells showed that the BNM compounds are cell-permeable and can also be employed for live-cell imaging. This is a new library which can be excited through a dark donor allowing for strong fluorescence emission in a wide range of wavelengths. Thus, the BNM library is well suited for high-throughput screening or multiplex experiments in biological applications by using a single laser excitation source. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Hands-free image capture, data tagging and transfer using Google Glass: a pilot study for improved wound care management.

    Directory of Open Access Journals (Sweden)

    Gabriel Aldaz

    Full Text Available Chronic wounds, including pressure ulcers, compromise the health of 6.5 million Americans and pose an annual estimated burden of $25 billion to the U.S. health care system. When treating chronic wounds, clinicians must use meticulous documentation to determine wound severity and to monitor healing progress over time. Yet, current wound documentation practices using digital photography are often cumbersome and labor intensive. The process of transferring photos into Electronic Medical Records (EMRs requires many steps and can take several days. Newer smartphone and tablet-based solutions, such as Epic Haiku, have reduced EMR upload time. However, issues still exist involving patient positioning, image-capture technique, and patient identification. In this paper, we present the development and assessment of the SnapCap System for chronic wound photography. Through leveraging the sensor capabilities of Google Glass, SnapCap enables hands-free digital image capture, and the tagging and transfer of images to a patient's EMR. In a pilot study with wound care nurses at Stanford Hospital (n=16, we (i examined feature preferences for hands-free digital image capture and documentation, and (ii compared SnapCap to the state of the art in digital wound care photography, the Epic Haiku application. We used the Wilcoxon Signed-ranks test to evaluate differences in mean ranks between preference options. Preferred hands-free navigation features include barcode scanning for patient identification, Z(15 = -3.873, p < 0.001, r = 0.71, and double-blinking to take photographs, Z(13 = -3.606, p < 0.001, r = 0.71. In the comparison between SnapCap and Epic Haiku, the SnapCap System was preferred for sterile image-capture technique, Z(16 = -3.873, p < 0.001, r = 0.68. Responses were divided with respect to image quality and overall ease of use. The study's results have contributed to the future implementation of new features aimed at enhancing mobile hands-free digital

  5. Hands-Free Image Capture, Data Tagging and Transfer Using Google Glass: A Pilot Study for Improved Wound Care Management

    Science.gov (United States)

    Aldaz, Gabriel; Shluzas, Lauren Aquino; Pickham, David; Eris, Ozgur; Sadler, Joel; Joshi, Shantanu; Leifer, Larry

    2015-01-01

    Chronic wounds, including pressure ulcers, compromise the health of 6.5 million Americans and pose an annual estimated burden of $25 billion to the U.S. health care system. When treating chronic wounds, clinicians must use meticulous documentation to determine wound severity and to monitor healing progress over time. Yet, current wound documentation practices using digital photography are often cumbersome and labor intensive. The process of transferring photos into Electronic Medical Records (EMRs) requires many steps and can take several days. Newer smartphone and tablet-based solutions, such as Epic Haiku, have reduced EMR upload time. However, issues still exist involving patient positioning, image-capture technique, and patient identification. In this paper, we present the development and assessment of the SnapCap System for chronic wound photography. Through leveraging the sensor capabilities of Google Glass, SnapCap enables hands-free digital image capture, and the tagging and transfer of images to a patient’s EMR. In a pilot study with wound care nurses at Stanford Hospital (n=16), we (i) examined feature preferences for hands-free digital image capture and documentation, and (ii) compared SnapCap to the state of the art in digital wound care photography, the Epic Haiku application. We used the Wilcoxon Signed-ranks test to evaluate differences in mean ranks between preference options. Preferred hands-free navigation features include barcode scanning for patient identification, Z(15) = -3.873, p < 0.001, r = 0.71, and double-blinking to take photographs, Z(13) = -3.606, p < 0.001, r = 0.71. In the comparison between SnapCap and Epic Haiku, the SnapCap System was preferred for sterile image-capture technique, Z(16) = -3.873, p < 0.001, r = 0.68. Responses were divided with respect to image quality and overall ease of use. The study’s results have contributed to the future implementation of new features aimed at enhancing mobile hands-free digital

  6. Transference of surface markers in X-ray, CT- and MR-imaging

    International Nuclear Information System (INIS)

    Grevelhoerster, T.; Poetter, R.; Prott, F.J.; Dittrich, M.

    1995-01-01

    By using pharmacological capsules and plastic tubes filled with oily contrast medium contraining iodine (Lipiodol; Byk Gulden), marking aids were developed which can be seen in similar definite limits within the framework of MRI-, CT- and conventional X-ray-Imaging. A method to view these new, artificial markers in combination with individual, anatomical landmarks is introduced. The marking aid/surface marker, fixed on anatomical reference structures on the skin, does not result in an additional burden for the patient. The new, artificial markers are also useful for making other structures recognizable, such as anatomical relation lines, center of the portal and edges in planning imaging for radiotherapy treatments and are used as leading and reference structures to compare localisation and extent of lesions in X-ray-, CT- and MRI. Marking aids/surface markers do not have to be changed in different imaging methods. (orig./MG) [de

  7. Net-based data transfer and automatic image fusion of metabolic (PET) and morphologic (CT/MRI) images for radiosurgical planning of brain tumors

    International Nuclear Information System (INIS)

    Baum, R.P.; Przetak, C.; Schmuecking, M.; Klener, G.; Surber, G.; Hamm, K.

    2002-01-01

    Aim: The main purpose of radiosurgery in comparison to conventional radiotherapy of brain tumors is to reach a higher radiation dose in the tumor and sparing normal brain tissue as much as possible. To reach this aim it is crucial to define the target volume extremely accurately. For this purpose, MRI and CT examinations are used for radiotherapy planning. In certain cases, however, metabolic information obtained by positron emission tomography (PET) may be useful to achieve a higher therapeutic accuracy by sparing important brain structures. This can be the case, i.e. in low grade astrocytomas for exact delineation of vital tumor as well as in differentiating scaring tissue from tumor recurrence and edema after operation. For this purpose, radiolabeled aminoacid analogues (e.g. C-11 methionine) and recently O-2-[ 18 F] Fluorethyl-L-Tyrosin (F-18 FET) have been introduced as PET tracers to detect the area of highest tumor metabolism which allows to obtain additional information as compared to FDG-PET that reflects the local glucose metabolism. In these cases, anatomical and metabolic data have to be combined with the technique of digital image fusion to exactly determine the target volume, the isodoses and the area where the highest dose has to be applied. Materials: We have set up a data transfer from the PET Center of the Zentralklinik Bad Berka with the Department of Stereotactic Radiation at the Helios Klinik Erfurt (distance approx. 25 km) to enable this kind of image fusion. PET data (ECAT EXACT 47, Siemens/CTI) are transferred to a workstation (NOVALIS) in the Dept. of Stereotactic Radiation to be co-registered with the CT or MRI data of the patient. All PET images are in DICOM format (obtained by using a HERMES computer, Nuclear Diagnostics, Sweden) and can easily be introduced into the NOVALIS workstation. The software uses the optimation of mutual information to achieve a good fusion quality. Sometimes manual corrections have to be performed to get an

  8. Extraction of Built-Up Areas Using Convolutional Neural Networks and Transfer Learning from SENTINEL-2 Satellite Images

    Science.gov (United States)

    Bramhe, V. S.; Ghosh, S. K.; Garg, P. K.

    2018-04-01

    With rapid globalization, the extent of built-up areas is continuously increasing. Extraction of features for classifying built-up areas that are more robust and abstract is a leading research topic from past many years. Although, various studies have been carried out where spatial information along with spectral features has been utilized to enhance the accuracy of classification. Still, these feature extraction techniques require a large number of user-specific parameters and generally application specific. On the other hand, recently introduced Deep Learning (DL) techniques requires less number of parameters to represent more abstract aspects of the data without any manual effort. Since, it is difficult to acquire high-resolution datasets for applications that require large scale monitoring of areas. Therefore, in this study Sentinel-2 image has been used for built-up areas extraction. In this work, pre-trained Convolutional Neural Networks (ConvNets) i.e. Inception v3 and VGGNet are employed for transfer learning. Since these networks are trained on generic images of ImageNet dataset which are having very different characteristics from satellite images. Therefore, weights of networks are fine-tuned using data derived from Sentinel-2 images. To compare the accuracies with existing shallow networks, two state of art classifiers i.e. Gaussian Support Vector Machine (SVM) and Back-Propagation Neural Network (BP-NN) are also implemented. Both SVM and BP-NN gives 84.31 % and 82.86 % overall accuracies respectively. Inception-v3 and VGGNet gives 89.43 % of overall accuracy using fine-tuned VGGNet and 92.10 % when using Inception-v3. The results indicate high accuracy of proposed fine-tuned ConvNets on a 4-channel Sentinel-2 dataset for built-up area extraction.

  9. EXTRACTION OF BUILT-UP AREAS USING CONVOLUTIONAL NEURAL NETWORKS AND TRANSFER LEARNING FROM SENTINEL-2 SATELLITE IMAGES

    Directory of Open Access Journals (Sweden)

    V. S. Bramhe

    2018-04-01

    Full Text Available With rapid globalization, the extent of built-up areas is continuously increasing. Extraction of features for classifying built-up areas that are more robust and abstract is a leading research topic from past many years. Although, various studies have been carried out where spatial information along with spectral features has been utilized to enhance the accuracy of classification. Still, these feature extraction techniques require a large number of user-specific parameters and generally application specific. On the other hand, recently introduced Deep Learning (DL techniques requires less number of parameters to represent more abstract aspects of the data without any manual effort. Since, it is difficult to acquire high-resolution datasets for applications that require large scale monitoring of areas. Therefore, in this study Sentinel-2 image has been used for built-up areas extraction. In this work, pre-trained Convolutional Neural Networks (ConvNets i.e. Inception v3 and VGGNet are employed for transfer learning. Since these networks are trained on generic images of ImageNet dataset which are having very different characteristics from satellite images. Therefore, weights of networks are fine-tuned using data derived from Sentinel-2 images. To compare the accuracies with existing shallow networks, two state of art classifiers i.e. Gaussian Support Vector Machine (SVM and Back-Propagation Neural Network (BP-NN are also implemented. Both SVM and BP-NN gives 84.31 % and 82.86 % overall accuracies respectively. Inception-v3 and VGGNet gives 89.43 % of overall accuracy using fine-tuned VGGNet and 92.10 % when using Inception-v3. The results indicate high accuracy of proposed fine-tuned ConvNets on a 4-channel Sentinel-2 dataset for built-up area extraction.

  10. A transfer-learning approach to image segmentation across scanners by maximizing distribution similarity

    DEFF Research Database (Denmark)

    van Opbroek, Annegreet; Ikram, M. Arfan; Vernooij, Meike W.

    2013-01-01

    Many successful methods for biomedical image segmentation are based on supervised learning, where a segmentation algorithm is trained based on manually labeled training data. For supervised-learning algorithms to perform well, this training data has to be representative for the target data. In pr...

  11. Transfer functions of US transducers for harmonic imaging and bubble respons

    NARCIS (Netherlands)

    van Neer, Paul L.M.J.; Matte, Guillaume; Sijl, J.; Borsboom, Jerome M.G.; de Jong, N.

    2007-01-01

    Current medical diagnostic echo systems are mostly using harmonic imaging. This means that a fundamental frequency (e.g., 2 MHz) is transmitted and the reflected and scattered higher harmonics (e.g., 4 and 6 MHz), produced by nonlinear propagation, are recorded. The signal level of these harmonics

  12. Integrated smartphone imaging of quantum dot photoluminescence and Förster resonance energy transfer

    Science.gov (United States)

    Petryayeva, Eleonora; Algar, W. Russ

    2015-06-01

    Smartphones and other mobile devices are emerging as promising analytical platforms for point-of-care diagnostics, particularly when combined with nanotechnology. For example, we have shown that the optical properties of semiconductor quantum dots (QDs) are well suited to photoluminescence (PL) detection with a smartphone camera. However, this previous work has utilized an external excitation source for interrogation of QD PL. In this proceeding, we demonstrate that the white-light LED photographic flashes built into smartphones can be optically filtered to yield blue light suitable for excitation of QD PL. Measurements were made by recording video with filtered flash illumination and averaging the frames of the video to obtain images with good signal-to-background ratios. These images permitted detection of green-emitting and red-emitting QDs at levels comparable to those possible with excitation using an external long-wave UV lamp. The optical properties of QDs proved to be uniquely suited to smartphone PL imaging, exhibiting emission that was 1-2 orders magnitude brighter than that of common fluorescent dyes under the same conditions. Excitation with the smartphone flash was also suitable for imaging of FRET between green-emitting QD donors and Alexa Fluor 555 (A555) fluorescent dye acceptors. No significant difference in FRET imaging capability was observed between excitation with the smartphone flash and a long-wave UV lamp. Although the smartphone flash did have some disadvantages compared to an external UV lamp, these disadvantages are potentially offset by the benefit of having excitation and detection integrated into the smartphone.

  13. Improved cloning efficiency and developmental potential in bovine somatic cell nuclear transfer with the oosight imaging system.

    Science.gov (United States)

    Kim, Eun Young; Park, Min Jee; Park, Hyo Young; Noh, Eun Ji; Noh, Eun Hyung; Park, Kyoung Sik; Lee, Jun Beom; Jeong, Chang Jin; Riu, Key Zung; Park, Se Pill

    2012-08-01

    In somatic cell nuclear transfer (SCNT) procedures, exquisite enucleation of the recipient oocyte is critical to cloning efficiency. The purpose of this study was to compare the effects of two enucleation systems, Hoechst staining and UV irradiation (hereafter, irradiation group) and Oosight imaging (hereafter, Oosight group), on the in vitro production of bovine SCNT embryos. In the Oosight group, the apoptotic index (2.8 ± 0.5 vs. 7.3 ± 1.2) was lower, and the fusion rate (75.6% vs. 62.9%), cleavage rate (78.0% vs. 63.7%), blastocyst rate (40.2% vs. 29.2%), and total cell number (128.3±4.8 vs. 112.2 ± 7.6) were higher than those in the irradiation group (all p<0.05). The overall efficiency after SCNT was twice as high in the Oosight group as that in the irradiation group (p<0.05). The relative mRNA expression levels of Oct4, Nanog, Interferon-tau, and Dnmt3A were higher and those of Caspase-3 and Hsp70 were lower in the Oosight group compared with the irradiation group (p<0.05). This is the first report to show the positive effect of the Oosight imaging system on molecular gene expression in the SCNT embryo. The Oosight imaging system may become the preferred choice for enucleation because it is less detrimental to the developmental potential of bovine SCNT embryos.

  14. Correction method of slit modulation transfer function on digital medical imaging system

    International Nuclear Information System (INIS)

    Kim, Jung Min; Jung, Hoi Woun; Min, Jung Whan; Im, Eon Kyung

    2006-01-01

    By using CR image pixel data, We examined the way how to calculate the MTF and digital characteristic curve. It can be changed to the text-file (Excel) from a pixel data which was printed with a digital x-ray equipment. In this place, We described the way how to figure out and correct the sharpness of a digital images of the MTF from FUJITA. Excel program was utilized to calculate from radiography of slit. Digital characteristic curve, Line Spread Function, Discrete Fourier Transform, Fast Fourier Transform digital specification curve, were indicated in regular sequence. A big advantage of this method, It can be understood easily and you can get results without costly program an without full knowledge of computer language. It shows many different values by using different correction methods. Therefore we need to be handy with appropriate correction method and we should try many experiments to get a precise MTF figures

  15. From calorimetry to medical imaging: a shining example of successful transfer!

    CERN Multimedia

    Caroline Duc

    2012-01-01

    A team at CERN has drawn inspiration from calorimetry methods developed for high-energy physics to create a new positron-emission tomography system for use in medical imaging, which they’ve dubbed AX-PET. With support from European and American laboratories*, the project is reaching fruition, as initial tests confirm its promise.   Snapshot of a “phantom”, a test object, surrounded by the AX-PET photon detectors. Positron-emission tomography (PET) is a medical imaging technique based on the matter-antimatter interaction that can provide a three-dimensional representation of the metabolic activity of an organ. To do so, radioactive marker molecules are first injected into the subject. As the marker decays, it emits positrons (antimatter particles), which are annihilated upon encountering electrons in the surrounding environment. The resulting flash, consisting of two photons, is detected by the PET machine. In conventional PET systems, it is impossible to improv...

  16. Transferability of species distribution models for the detection of an invasive alien bryophyte using imaging spectroscopy data

    Science.gov (United States)

    Skowronek, Sandra; Van De Kerchove, Ruben; Rombouts, Bjorn; Aerts, Raf; Ewald, Michael; Warrie, Jens; Schiefer, Felix; Garzon-Lopez, Carol; Hattab, Tarek; Honnay, Olivier; Lenoir, Jonathan; Rocchini, Duccio; Schmidtlein, Sebastian; Somers, Ben; Feilhauer, Hannes

    2018-06-01

    Remote sensing is a promising tool for detecting invasive alien plant species. Mapping and monitoring those species requires accurate detection. So far, most studies relied on models that are locally calibrated and validated against available field data. Consequently, detecting invasive alien species at new study areas requires the acquisition of additional field data which can be expensive and time-consuming. Model transfer might thus provide a viable alternative. Here, we mapped the distribution of the invasive alien bryophyte Campylopus introflexus to i) assess the feasibility of spatially transferring locally calibrated models for species detection between four different heathland areas in Germany and Belgium and ii) test the potential of combining calibration data from different sites in one species distribution model (SDM). In a first step, four different SDMs were locally calibrated and validated by combining field data and airborne imaging spectroscopy data with a spatial resolution ranging from 1.8 m to 4 m and a spectral resolution of about 10 nm (244 bands). A one-class classifier, Maxent, which is based on the comparison of probability densities, was used to generate all SDMs. In a second step, each model was transferred to the three other study areas and the performance of the models for predicting C. introflexus occurrences was assessed. Finally, models combining calibration data from three study areas were built and tested on the remaining fourth site. In this step, different combinations of Maxent modelling parameters were tested. For the local models, the area under the curve for a test dataset (test AUC) was between 0.57-0.78, while the test AUC for the single transfer models ranged between 0.45-0.89. For the combined models the test AUC was between 0.54-0.9. The success of transferring models calibrated in one site to another site highly depended on the respective study site; the combined models provided higher test AUC values than the locally

  17. Amide Proton Transfer Magnetic Resonance Imaging of Alzheimer′s Disease at 3.0 Tesla: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Rui Wang

    2015-01-01

    Full Text Available Background: Amide proton transfer (APT imaging has recently emerged as an important contrast mechanism for magnetic resonance imaging (MRI in the field of molecular and cellular imaging. The aim of this study was to evaluate the feasibility of APT imaging to detect cerebral abnormality in patients with Alzheimer′s disease (AD at 3.0 Tesla. Methods: Twenty AD patients (9 men and 11 women; age range, 67-83 years and 20 age-matched normal controls (11 men and 9 women; age range, 63-82 years underwent APT and traditional MRI examination on a 3.0 Tesla MRI system. The magnetic resonance ratio asymmetry (MTR asym values at 3.5 ppm of bilateral hippocampi (Hc, temporal white matter regions, occipital white matter regions, and cerebral peduncles were measured on oblique axial APT images. MTR asym (3.5 ppm values of the cerebral structures between AD patients and control subjects were compared with independent samples t-test. Controlling for age, partial correlation analysis was used to investigate the associations between mini-mental state examination (MMSE and the various MRI measures among AD patients. Results: Compared with normal controls, MTR asym (3.5 ppm values of bilateral Hc were significantly increased in AD patients (right 1.24% ± 0.21% vs. 0.83% ± 0.19%, left 1.18% ± 0.18% vs. 0.80%± 0.17%, t = 3.039, 3.328, P = 0.004, 0.002, respectively. MTR asym (3.5 ppm values of bilateral Hc were significantly negatively correlated with MMSE (right r = −0.559, P = 0.013; left r = −0.461, P = 0.047. Conclusions: Increased MTR asym (3.5 ppm values of bilateral Hc in AD patients and its strong correlations with MMSE suggest that APT imaging could potentially provide imaging biomarkers for the noninvasive molecular diagnosis of AD.

  18. Transferability of Object-Oriented Image Analysis Methods for Slum Identification

    Directory of Open Access Journals (Sweden)

    Alfred Stein

    2013-08-01

    Full Text Available Updated spatial information on the dynamics of slums can be helpful to measure and evaluate progress of policies. Earlier studies have shown that semi-automatic detection of slums using remote sensing can be challenging considering the large variability in definition and appearance. In this study, we explored the potential of an object-oriented image analysis (OOA method to detect slums, using very high resolution (VHR imagery. This method integrated expert knowledge in the form of a local slum ontology. A set of image-based parameters was identified that was used for differentiating slums from non-slum areas in an OOA environment. The method was implemented on three subsets of the city of Ahmedabad, India. Results show that textural features such as entropy and contrast derived from a grey level co-occurrence matrix (GLCM and the size of image segments are stable parameters for classification of built-up areas and the identification of slums. Relation with classified slum objects, in terms of enclosed by slums and relative border with slums was used to refine classification. The analysis on three different subsets showed final accuracies ranging from 47% to 68%. We conclude that our method produces useful results as it allows including location specific adaptation, whereas generically applicable rulesets for slums are still to be developed.

  19. Three-Dimensional Reconstruction of Nuclear Envelope Architecture Using Dual-Color Metal-Induced Energy Transfer Imaging.

    Science.gov (United States)

    Chizhik, Anna M; Ruhlandt, Daja; Pfaff, Janine; Karedla, Narain; Chizhik, Alexey I; Gregor, Ingo; Kehlenbach, Ralph H; Enderlein, Jörg

    2017-12-26

    The nuclear envelope, comprising the inner and the outer nuclear membrane, separates the nucleus from the cytoplasm and plays a key role in cellular functions. Nuclear pore complexes (NPCs), which are embedded in the nuclear envelope, control transport of macromolecules between the two compartments. Here, using dual-color metal-induced energy transfer (MIET), we determine the axial distance between Lap2β and Nup358 as markers for the inner nuclear membrane and the cytoplasmic side of the NPC, respectively. Using MIET imaging, we reconstruct the 3D profile of the nuclear envelope over the whole basal area, with an axial resolution of a few nanometers. This result demonstrates that optical microscopy can achieve nanometer axial resolution in biological samples and without recourse to complex interferometric approaches.

  20. Influence of transfer gate design and bias on the radiation hardness of pinned photodiode CMOS image sensors

    International Nuclear Information System (INIS)

    Goiffon, V.; Estribeau, M.; Cervantes, P.; Molina, R.; Magnan, P.; Gaillardin, M.

    2014-01-01

    The effects of Cobalt 60 gamma-ray irradiation on pinned photodiode (PPD) CMOS image sensors (CIS) are investigated by comparing the total ionizing dose (TID) response of several transfer gate (TG) and PPD designs manufactured using a 180 nm CIS process. The TID induced variations of charge transfer efficiency (CTE), pinning voltage, equilibrium full well capacity (EFWC), full well capacity (FWC) and dark current measured on the different pixel designs lead to the conclusion that only three degradation sources are responsible for all the observed radiation effects: the pre-metal dielectric (PMD) positive trapped charge, the TG sidewall spacer positive trapped charge and, with less influence, the TG channel shallow trench isolation (STI) trapped charge. The different FWC evolutions with TID presented here are in very good agreement with a recently proposed analytical model. This work also demonstrates that the peripheral STI is not responsible for the observed degradations and thus that the enclosed layout TG design does not improve the radiation hardness of PPD CIS. The results of this study also lead to the conclusion that the TG OFF voltage bias during irradiation has no influence on the radiation effects. Alternative design and process solutions to improve the radiation hardness of PPD CIS are discussed. (authors)

  1. Optimal Subset Selection of Time-Series MODIS Images and Sample Data Transfer with Random Forests for Supervised Classification Modelling.

    Science.gov (United States)

    Zhou, Fuqun; Zhang, Aining

    2016-10-25

    Nowadays, various time-series Earth Observation data with multiple bands are freely available, such as Moderate Resolution Imaging Spectroradiometer (MODIS) datasets including 8-day composites from NASA, and 10-day composites from the Canada Centre for Remote Sensing (CCRS). It is challenging to efficiently use these time-series MODIS datasets for long-term environmental monitoring due to their vast volume and information redundancy. This challenge will be greater when Sentinel 2-3 data become available. Another challenge that researchers face is the lack of in-situ data for supervised modelling, especially for time-series data analysis. In this study, we attempt to tackle the two important issues with a case study of land cover mapping using CCRS 10-day MODIS composites with the help of Random Forests' features: variable importance, outlier identification. The variable importance feature is used to analyze and select optimal subsets of time-series MODIS imagery for efficient land cover mapping, and the outlier identification feature is utilized for transferring sample data available from one year to an adjacent year for supervised classification modelling. The results of the case study of agricultural land cover classification at a regional scale show that using only about a half of the variables we can achieve land cover classification accuracy close to that generated using the full dataset. The proposed simple but effective solution of sample transferring could make supervised modelling possible for applications lacking sample data.

  2. Transferring results from NIR-hyperspectral to NIR-multispectral imaging systems

    DEFF Research Database (Denmark)

    Calvini, Rosalba; Amigo Rubio, Jose Manuel; Ulrici, Alessandro

    2017-01-01

    commercially available filters matching the selected spectral regions, and used to calculate multivariate classification models with Partial Least Squares-Discriminant Analysis (PLS-DA) and sparse PLS-DA. Proper strategies for the definition of the training set and the selection of the most effective......Due to the differences in terms of both price and quality, the availability of effective instrumentation to discriminate between Arabica and Robusta coffee is extremely important. To this aim, the use of multispectral imaging systems could provide reliable and accurate real-time monitoring...

  3. Grading diffuse gliomas without intense contrast enhancement by amide proton transfer MR imaging: comparisons with diffusion- and perfusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Togao, Osamu; Hiwatashi, Akio; Yamashita, Koji; Kikuchi, Kazufumi; Honda, Hiroshi [Kyushu University, Department of Clinical Radiology, Graduate School of Medical Sciences, Fukuoka (Japan); Keupp, Jochen [Philips Research, Hamburg (Germany); Yoshimoto, Koji; Kuga, Daisuke; Iihara, Koji [Kyushu University, Department of Neurosurgery, Graduate School of Medical Sciences, Fukuoka (Japan); Yoneyama, Masami [Philips Electronics Japan, Tokyo (Japan); Suzuki, Satoshi O.; Iwaki, Toru [Kyushu University, Department of Neuropathology, Graduate School of Medical Sciences, Fukuoka (Japan); Takahashi, Masaya [Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX (United States)

    2017-02-15

    To investigate whether amide proton transfer (APT) MR imaging can differentiate high-grade gliomas (HGGs) from low-grade gliomas (LGGs) among gliomas without intense contrast enhancement (CE). This retrospective study evaluated 34 patients (22 males, 12 females; age 36.0 ± 11.3 years) including 20 with LGGs and 14 with HGGs, all scanned on a 3T MR scanner. Only tumours without intense CE were included. Two neuroradiologists independently performed histogram analyses to measure the 90th-percentile (APT{sub 90}) and mean (APT{sub mean}) of the tumours' APT signals. The apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) were also measured. The parameters were compared between the groups with Student's t-test. Diagnostic performance was evaluated with receiver operating characteristic (ROC) analysis. The APT{sub 90} (2.80 ± 0.59 % in LGGs, 3.72 ± 0.89 in HGGs, P = 0.001) and APT{sub mean} (1.87 ± 0.49 % in LGGs, 2.70 ± 0.58 in HGGs, P = 0.0001) were significantly larger in the HGGs compared to the LGGs. The ADC and rCBV values were not significantly different between the groups. Both the APT{sub 90} and APT{sub mean} showed medium diagnostic performance in this discrimination. APT imaging is useful in discriminating HGGs from LGGs among diffuse gliomas without intense CE. (orig.)

  4. Imaging the Ultrafast Photoelectron Transfer Process in Alizarin-TiO2

    Directory of Open Access Journals (Sweden)

    Tatiana Gomez

    2015-07-01

    Full Text Available In this work, we adopt a quantum mechanical approach based on time-dependent density functional theory (TDDFT to study the optical and electronic properties of alizarin supported on TiO2 nano-crystallites, as a prototypical dye-sensitized solar cell. To ensure proper alignment of the donor (alizarin and acceptor (TiO2 nano-crystallite levels, static optical excitation spectra are simulated using time-dependent density functional theory in response. The ultrafast photoelectron transfer from the dye to the cluster is simulated using an explicitly time-dependent, one-electron TDDFT ansatz. The model considers the δ-pulse excitation of a single active electron localized in the dye to the complete set of energetically accessible, delocalized molecular orbitals of the dye/nano-crystallite complex. A set of quantum mechanical tools derived from the transition electronic flux density is introduced to visualize and analyze the process in real time. The evolution of the created wave packet subject to absorbing boundary conditions at the borders of the cluster reveal that, while the electrons of the aromatic rings of alizarin are heavily involved in an ultrafast charge redistribution between the carbonyl groups of the dye molecule, they do not contribute positively to the electron injection and, overall, they delay the process.

  5. Imaging the electron transfer reaction of Ne2+ with Ar using position-sensitive coincidence spectroscopy

    International Nuclear Information System (INIS)

    Harper, Sarah M; Hu Wanping; Price, Stephen D

    2002-01-01

    A new experiment, employing position-sensitive detection coupled with time-of-flight mass spectrometry, has been used to investigate the single-electron transfer reaction between Ne 2+ and Ar by detecting the resulting pairs of singly charged ions in coincidence. The experimental technique allows the determination of the individual velocity vectors of the ionic products, in the centre-of-mass frame, for each reactive event detected. The experiments show that forward scattering dominates the reactivity, although a bimodal angular distribution is apparent. In addition, the spectra show that at laboratory frame collision energies from 4-14 eV the reactivity is dominated by Ne 2+ (2p 4 , 3 P) accepting an electron from an argon atom to form the ground state of Ne + together with an Ar + ion in an excited electronic level, predominantly arising from the Ar + (3s 2 3p 4 3d) configuration. The form of this reactivity, and the differences between the reactivity observed in these experiments and those performed at higher collision energies, are well reproduced by Landau-Zener theory

  6. Chemical Exchange Saturation Transfer in Chemical Reactions: A Mechanistic Tool for NMR Detection and Characterization of Transient Intermediates.

    Science.gov (United States)

    Lokesh, N; Seegerer, Andreas; Hioe, Johnny; Gschwind, Ruth M

    2018-02-07

    The low sensitivity of NMR and transient key intermediates below detection limit are the central problems studying reaction mechanisms by NMR. Sensitivity can be enhanced by hyperpolarization techniques such as dynamic nuclear polarization or the incorporation/interaction of special hyperpolarized molecules. However, all of these techniques require special equipment, are restricted to selective reactions, or undesirably influence the reaction pathways. Here, we apply the chemical exchange saturation transfer (CEST) technique for the first time to NMR detect and characterize previously unobserved transient reaction intermediates in organocatalysis. The higher sensitivity of CEST and chemical equilibria present in the reaction pathway are exploited to access population and kinetics information on low populated intermediates. The potential of the method is demonstrated on the proline-catalyzed enamine formation for unprecedented in situ detection of a DPU stabilized zwitterionic iminium species, the elusive key intermediate between enamine and oxazolidinones. The quantitative analysis of CEST data at 250 K revealed the population ratio of [Z-iminium]/[exo-oxazolidinone] 0.02, relative free energy +8.1 kJ/mol (calculated +7.3 kJ/mol), and free energy barrier of +45.9 kJ/mol (ΔG ⧧ calc. (268 K) = +42.2 kJ/mol) for Z-iminium → exo-oxazolidinone. The findings underpin the iminium ion participation in enamine formation pathway corroborating our earlier theoretical prediction and help in better understanding. The reliability of CEST is validated using 1D EXSY-build-up techniques at low temperature (213 K). The CEST method thus serves as a new tool for mechanistic investigations in organocatalysis to access key information, such as chemical shifts, populations, and reaction kinetics of intermediates below the standard NMR detection limit.

  7. DEVELOPMENT OF EVALUATION OF A QUANTITATIVE VIDEO-FLUORESCENCE IMAGING SYSTEM AND FLUORESCENT TRACER FOR MEASURING TRANSFER OF PESTICIDE RESIDUES FROM SURFACES TO HANDS WITH REPEATED CONTACTS

    Science.gov (United States)

    A video imaging system and the associated quantification methods have been developed for measurement of the transfers of a fluorescent tracer from surfaces to hands. The highly fluorescent compound riboflavin (Vitamin B2), which is also water soluble and non-toxic, was chosen as...

  8. A magnetization transfer imaging study of bilateral optic radiation and visual cortex in patients with primary glaucoma

    International Nuclear Information System (INIS)

    Liang Wenwen; Zhang Xuelin; Jiang Xiaoyong; Xu Yongming; Yang Zhihui; Zhang Yan; Chang Renmin; Wang Jianping; Wu Guijun

    2012-01-01

    Objective: To analyse the changes in bilateral optic radiation and visual cortex in patients with primary glaucoma detected by magnetization transfer imaging (MTI), and try to explore the influence of the disease on posterior visual pathway. Methods: MTI was performed in 20 patients with primary glaucoma with normal signal on conventional magnetic resonance imaging (MRI). The same scanning was performed in 31 matched healthy controls. MTI was obtained using spoiled gradient recalled acquisition sequence (SPGR). Magnetization transfer ratio (MTR) of bilateral optic radiation and visual cortex was measured after post-processing. The MTR value differences of the same area between two groups were compared by independent-sample t test or Satterthwaite t test if variances were not equality. Result: The MTR value in the left and right optic radiation were (32.8 ± 2.2)% and (32.7 ± 2.0)% in the glaucoma group, (34.6 ± 1.4 )% and (34.8 ± 1.3)% in the control group. There was a statistically significant difference between the two groups (left t=3.284, right t=4.040; P<0.01). The MTR value of the left and right visual cortex were (30.1± 2.0)% and (30.8 ± 1.8)% in the glaucoma group, and (32.3 ± 1.2 )% and (32.4 ± 1.2)% in the control group. Statistically significant difference was found between the two groups (left t=4.319, right t=3.445; P<0.01). Conclusions: Potential neuropathology changes occurring in the posterior visual pathway of patients with glaucoma indicate that the whole visual pathway may be involved by glaucoma.The micro physiological changes can be detected by MTI which can not be found by conventional MRI. It is a useful method of studying trans-synaptic damage of visual pathway n vivo glaucoma which provides more information for guiding the clinic diagnosis, cure and prognosis of glaucoma. (authors)

  9. Age-related changes in conventional and magnetization transfer MR imaging in elderly people: comparison with neurocognitive performance

    International Nuclear Information System (INIS)

    Lee, Ki Yeol; Kim, Taik Kun; Park, Min Kyu; Ko, Sung Yu; Song, In Chan; Cho, Ik Hwan

    2004-01-01

    This study was designed to compare three different measures of the elderly human brain; the magnetization transfer ratio (MTR) histogram, the percentage of brain parenchymal volume, and the volume of T2 hyperintense areas in terms of correlations with the study subjects'neurocognitive performance. Thirty-five healthy community-dwelling elderly volunteers aged 60-82 years underwent dual fast spin-echo (FSE) imaging and magnetization transfer imaging. A semi-automated technique was used to generate the MTR histogram, the brain parenchymal volume, and the T2 lesion volume. The subjects'neurocognitive performance was assessed by using the Korean-Mini Mental State Examination (K-MMSE) and additional tests. The peak height of the MTR (PHMTR), the percentage of brain parenchymal volume (PBV), and the normalized T2 lesion volume (T2LV) were compared between the normal group. (Z score on the K-MMSE ≥ -2, n=23) and the mild cognitive impairment group (Z score on the K-MMSE < -2, N=12), and these parameters were correlated with age and various neurocognitive performance scores. The PHMTR was significantly lower in the cognitively impaired subjects than the PHMTR in the normal subjects (ρ = 0.005). The PBV scores were lower in the cognitively impaired subjects than in the normal subjects (ρ = 0.02). The T2LV scores were significantly higher in the cognitively impaired subjects (ρ = 0.01). An inverse correlation was found between the PHMTR and T2LV (r = -0.747, ρ < 0.001), and also between the PBV and T2LV (r = -0.823, ρ < 0.001). A positive correlation was observed between the PHMTR and the PBV (r = 0.846, ρ < 0.001). Scores on the various neurocognitive tests were positively correlated with the PHMTR (6 of 7 items) and the PBV (5 of 7 items), and they were negatively correlated with the T2LV (5 of 7 items). Our findings of a correlation among the PBV, the T2LV, and the PHMTR suggest that MTR histograms and the PBV and T2LV can be used as a reliable method and valid

  10. Added value of amide proton transfer imaging to conventional and perfusion MR imaging for evaluating the treatment response of newly diagnosed glioblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kye Jin; Kim, Ho Sung; Park, Ji Eun; Shim, Woo Hyun; Kim, Sang Joon [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Smith, Seth A. [Vanderbilt University Institute of Imaging Science, Vanderbilt University, Department of Radiology and Radiological Sciences, Nashville, TN (United States)

    2016-12-15

    To determine the added value of amide proton transfer (APT) imaging to conventional and perfusion MRI for differentiating tumour progression (TP) from the treatment-related effect (TE) in patients with post-treatment glioblastomas. Sixty-five consecutive patients with enlarging contrast-enhancing lesions following concurrent chemoradiotherapy were assessed using contrast-enhanced T1-weighted MRI (CE-T1WI), 90th percentile histogram parameters of normalized cerebral blood volume (nCBV90) and APT asymmetry value (APT90). Diagnostic performance was determined using the area under the receiver operating characteristic curve (AUC) and cross validations. There were statistically significant differences in the mean APT90 between the TP and the TE groups (3.87-4.01 % vs. 1.38-1.41 %; P <.001). Compared with CE-T1WI alone, the addition of APT90 to CE-T1WI significantly improved cross-validated AUC from 0.58-0.74 to 0.89-0.91 for differentiating TP from TE. The combination of CE-T1WI, nCBV90 and APT90 resulted in greater diagnostic accuracy for differentiating TP from TE than the combination of CE-T1WI and nCBV90 (cross-validated AUC, 0.95-0.97 vs. 0.84-0.91). The inter-reader agreement between the expert and trainee was excellent for the measurements of APT90 (intraclass correlation coefficient, 0.94). Adding APT imaging to conventional and perfusion MRI improves the diagnostic performance for differentiating TP from TE. (orig.)

  11. Magnetization Transfer Magnetic Resonance Imaging Noninvasively Detects Renal Fibrosis in Swine Atherosclerotic Renal Artery Stenosis at 3.0 T.

    Science.gov (United States)

    Jiang, Kai; Ferguson, Christopher M; Woollard, John R; Zhu, Xiangyang; Lerman, Lilach O

    2017-11-01

    Renal fibrosis is a useful biomarker for diagnosis and evaluation of therapeutic interventions of renal diseases but often requires invasive testing. Magnetization transfer magnetic resonance imaging (MT-MRI), which evaluates the presence of macromolecules, offers a noninvasive tool to probe renal fibrosis in murine renal artery stenosis (RAS) at 16.4 T. In this study, we aimed to identify appropriate imaging parameters for collagen detection at 3.0 T MRI and to test the utility of MT-MRI in measuring renal fibrosis in a swine model of atherosclerotic RAS (ARAS). To select the appropriate offset frequency, an MT-MRI study was performed on a phantom containing 0% to 40% collagen I and III with offset frequencies from -1600 to +1600 Hz and other MT parameters empirically set as pulse width at 16 milliseconds and flip angle at 800 degrees. Then selected MT parameters were used in vivo on pigs 12 weeks after sham (n = 8) or RAS (n = 10) surgeries. The ARAS pigs were fed with high-cholesterol diet to induce atherosclerosis. The MT ratio (MTR) was compared with ex vivo renal fibrosis measured using Sirius-red staining. Offset frequencies at 600 and 1000 Hz were selected for collagen detection without direct saturation of free water signal, and subsequently applied in vivo. The ARAS kidneys showed mild cortical and medullary fibrosis by Sirius-red staining. The cortical and medullary MTRs at 600 and 1000 Hz were both increased. Renal fibrosis measured ex vivo showed good linear correlations with MTR at 600 (cortex: Pearson correlation coefficient r = 0.87, P 3.0 T. Therefore, MT-MRI may potentially be clinically applicable and useful for detection and monitoring of renal pathology in subjects with RAS.

  12. The effect of magnetisation transfer contrast on cerebrospinal fluid on motion artefacts on fluid-attenuated inversion-recovery images

    International Nuclear Information System (INIS)

    Aprile, I.; Principi, M.; Ottaviano, P.; Scapeccia, M.

    2003-01-01

    We assessed possible advantages of the use of fluid-attenuated inversion-recovery (FLAIR) sequences with magnetisation-transfer contrast (MTC) over conventional FLAIR images. We carried out cranial MRI at 1 tesla on 50 patients with both sequences. In nine patients with multiple sclerosis (MS) we performed a quantitative comparison of the two sequences, looking at the contrast-to-noise ratio between lesions and normal white matter and counting the number of lesions shown using each method. A qualitative comparison on all patients consisted of the analysis of the appearance of the normal parenchyma, of any lesions, and of artefacts, with particular reference to cerebrospinal fluid (CSF) motion artefacts. The quantitative analysis showed no meaningful difference between the two sequences. The cerebral parenchyma and lesions appeared substantially the same with both techniques. With FLAIR MTC there was a clear, and consistent reduction in CSF motion artefacts. FLAIR MTC sequences can usefully be used in place of the conventional sequence at 1 tesla. (orig.)

  13. Bioluminescence resonance energy transfer (BRET) imaging of protein–protein interactions within deep tissues of living subjects

    Science.gov (United States)

    Dragulescu-Andrasi, Anca; Chan, Carmel T.; Massoud, Tarik F.; Gambhir, Sanjiv S.

    2011-01-01

    Identifying protein–protein interactions (PPIs) is essential for understanding various disease mechanisms and developing new therapeutic approaches. Current methods for assaying cellular intermolecular interactions are mainly used for cells in culture and have limited use for the noninvasive assessment of small animal disease models. Here, we describe red light-emitting reporter systems based on bioluminescence resonance energy transfer (BRET) that allow for assaying PPIs both in cell culture and deep tissues of small animals. These BRET systems consist of the recently developed Renilla reniformis luciferase (RLuc) variants RLuc8 and RLuc8.6, used as BRET donors, combined with two red fluorescent proteins, TagRFP and TurboFP635, as BRET acceptors. In addition to the native coelenterazine luciferase substrate, we used the synthetic derivative coelenterazine-v, which further red-shifts the emission maxima of Renilla luciferases by 35 nm. We show the use of these BRET systems for ratiometric imaging of both cells in culture and deep-tissue small animal tumor models and validate their applicability for studying PPIs in mice in the context of rapamycin-induced FK506 binding protein 12 (FKBP12)-FKBP12 rapamycin binding domain (FRB) association. These red light-emitting BRET systems have great potential for investigating PPIs in the context of drug screening and target validation applications. PMID:21730157

  14. Magnetisation transfer MR imaging of the kidney: evaluation at 3.0 T in association with renal function

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Katsuyoshi [Kawasaki Medical School, Department of Diagnostic Radiology, Kurashiki, Okayama (Japan); Kurashiki Daiichi Hospital, Department of Radiology, Kurashiki, Okayama (Japan); Hayashida, Minoru; Izumitani, Shogo; Fujimine, Tomoko; Onishi, Takeo; Genba, Katsuhiro [Kurashiki Daiichi Hospital, Department of Radiology, Kurashiki, Okayama (Japan)

    2013-08-15

    To evaluate the feasibility of using magnetisation transfer (MT) MRI of the kidney at 3.0 T to assess renal function. Forty-four patients who underwent abdominal MRI on a 3.0-T system including gradient-echo (GRE) sequences with and without MT pulse were included. In each patient, MT ratio (MTR) of the renal cortex and medulla was measured by using regions of interest (ROIs) placed on the MTR map image. Regression analysis showed good correlation between estimated glomerular filtration rate (eGFR) and MTR of the renal cortex (r = -0.645, P < 0.0001). Among 44 patients, 22 were categorised as the normal renal function group and 22 were classified as the decreased eGFR group. The mean MTR of the renal cortex in patients with decreased eGFR (mean MTR, 30.7 {+-} 3.2 %) was significantly higher (P < 0.0001) than that in patients with normal renal function (mean MTR, 25.3 {+-} 2.2 %), although the mean MTRs of the renal medulla in the two groups were not significantly different. There was good correlation between eGFR and MTR of the renal cortex derived from MT MRI at 3.0 T. This technique may have the potential to evaluate the degree of renal function non-invasively in patients with renal impairment. (orig.)

  15. Live Imaging of HIV-1 Transfer across T Cell Virological Synapse to Epithelial Cells that Promotes Stromal Macrophage Infection.

    Science.gov (United States)

    Real, Fernando; Sennepin, Alexis; Ganor, Yonatan; Schmitt, Alain; Bomsel, Morgane

    2018-05-08

    During sexual intercourse, HIV-1 crosses epithelial barriers composing the genital mucosa, a poorly understood feature that requires an HIV-1-infected cell vectoring efficient mucosal HIV-1 entry. Therefore, urethral mucosa comprising a polarized epithelium and a stroma composed of fibroblasts and macrophages were reconstructed in vitro. Using this system, we demonstrate by live imaging that efficient HIV-1 transmission to stromal macrophages depends on cell-mediated transfer of the virus through virological synapses formed between HIV-1-infected CD4 + T cells and the epithelial cell mucosal surface. We visualized HIV-1 translocation through mucosal epithelial cells via transcytosis in regions where virological synapses occurred. In turn, interleukin-13 is secreted and HIV-1 targets macrophages, which develop a latent state of infection reversed by lipopolysaccharide (LPS) activation. The live observation of virological synapse formation reported herein is key in the design of vaccines and antiretroviral therapies aimed at blocking HIV-1 access to cellular reservoirs in genital mucosa. Copyright © 2018. Published by Elsevier Inc.

  16. Magnetisation transfer MR imaging of the kidney: evaluation at 3.0 T in association with renal function

    International Nuclear Information System (INIS)

    Ito, Katsuyoshi; Hayashida, Minoru; Izumitani, Shogo; Fujimine, Tomoko; Onishi, Takeo; Genba, Katsuhiro

    2013-01-01

    To evaluate the feasibility of using magnetisation transfer (MT) MRI of the kidney at 3.0 T to assess renal function. Forty-four patients who underwent abdominal MRI on a 3.0-T system including gradient-echo (GRE) sequences with and without MT pulse were included. In each patient, MT ratio (MTR) of the renal cortex and medulla was measured by using regions of interest (ROIs) placed on the MTR map image. Regression analysis showed good correlation between estimated glomerular filtration rate (eGFR) and MTR of the renal cortex (r = -0.645, P < 0.0001). Among 44 patients, 22 were categorised as the normal renal function group and 22 were classified as the decreased eGFR group. The mean MTR of the renal cortex in patients with decreased eGFR (mean MTR, 30.7 ± 3.2 %) was significantly higher (P < 0.0001) than that in patients with normal renal function (mean MTR, 25.3 ± 2.2 %), although the mean MTRs of the renal medulla in the two groups were not significantly different. There was good correlation between eGFR and MTR of the renal cortex derived from MT MRI at 3.0 T. This technique may have the potential to evaluate the degree of renal function non-invasively in patients with renal impairment. (orig.)

  17. Data and image transfer using mobile phones to strengthen microscopy-based diagnostic services in low and middle income country laboratories.

    Directory of Open Access Journals (Sweden)

    Coosje J Tuijn

    Full Text Available BACKGROUND: The emerging market of mobile phone technology and its use in the health sector is rapidly expanding and connecting even the most remote areas of world. Distributing diagnostic images over the mobile network for knowledge sharing, feedback or quality control is a logical innovation. OBJECTIVE: To determine the feasibility of using mobile phones for capturing microscopy images and transferring these to a central database for assessment, feedback and educational purposes. METHODS: A feasibility study was carried out in Uganda. Images of microscopy samples were taken using a prototype connector that could fix a variety of mobile phones to a microscope. An Information Technology (IT platform was set up for data transfer from a mobile phone to a website, including feedback by text messaging to the end user. RESULTS: Clear images were captured using mobile phone cameras of 2 megapixels (MP up to 5MP. Images were sent by mobile Internet to a website where they were visualized and feedback could be provided to the sender by means of text message. CONCLUSION: The process of capturing microscopy images on mobile phones, relaying them to a central review website and feeding back to the sender is feasible and of potential benefit in resource poor settings. Even though the system needs further optimization, it became evident from discussions with stakeholders that there is a demand for this type of technology.

  18. Applying Amide Proton Transfer MR Imaging to Hybrid Brain PET/MR: Concordance with Gadolinium Enhancement and Added Value to [18F]FDG PET.

    Science.gov (United States)

    Sun, Hongzan; Xin, Jun; Zhou, Jinyuan; Lu, Zaiming; Guo, Qiyong

    2018-06-01

    The purpose of this study is to evaluate the diagnostic concordance and metric correlations of amide proton transfer (APT) imaging with gadolinium-enhanced magnetic resonance imaging (MRI) and 2-deoxy-2-[ 18 F-]fluoro-D-glucose ([ 18 F]FDG) positron emission tomography (PET), using hybrid brain PET/MRI. Twenty-one subjects underwent brain gadolinium-enhanced [ 18 F]FDG PET/MRI prospectively. Imaging accuracy was compared between unenhanced MRI, MRI with enhancement, APT-weighted (APTW) images, and PET based on six diagnostic criteria. Among tumors, the McNemar test was further used for concordance assessment between gadolinium-enhanced imaging, APT imaging, and [ 18 F]FDG PET. As well, the relation of metrics between APT imaging and PET was analyzed by the Pearson correlation analysis. APT imaging and gadolinium-enhanced MRI showed superior and similar diagnostic accuracy. APTW signal intensity and gadolinium enhancement were concordant in 19 tumors (100 %), while high [ 18 F]FDG avidity was shown in only 12 (63.2 %). For the metrics from APT imaging and PET, there was significant correlation for 13 hypermetabolic tumors (P PET in the evaluation of tumor metabolic activity during brain PET/MR studies.

  19. Chemistry of paramagnetic and diamagnetic contrast agents for Magnetic Resonance Imaging and Spectroscopy

    International Nuclear Information System (INIS)

    Perez-Mayoral, Elena; Negri, Viviana; Soler-Padros, Jordi; Cerdan, Sebastian; Ballesteros, Paloma

    2008-01-01

    We provide a brief overview of the chemistry and most relevant properties of paramagnetic and diamagnetic contrast agents (CAs) for Magnetic Resonance Imaging and Magnetic Resonance Spectroscopic Imaging. Paramagnetic CAs for MRI consist mainly of Gd(III) complexes from linear or macrocyclic polyaminopolycarboxylates. These agents reduce, the relaxation times T 1 and T 2 of the water protons in a concentration dependent manner, increasing selectively MRI contrast in those regions in which they accumulate. In most instances they provide anatomical information on the localization of lesions and in some specific cases they may allow to estimate some physiological properties of tissues including mainly vascular performance. Because of its ability to discriminate easily between normal and diseased tissue, extracellular pH (pH e ) has been added recently, to the battery of variables amenable to MRI investigation. A variety of Gd(III) containing macrocycles sensitive to pH, endogenous or exogenous polypeptides or even liposomes have been investigated for this purpose, using the pH dependence of their relaxivity or magnetization transfer rate constant (chemical exchange saturation transfer, CEST). Many environmental circumstances in addition to pH affect, however, relaxivity or magnetization transfer rate constants of these agents, making the results of pH measurements by MRI difficult to interpret. To overcome these limitations, our laboratory synthesized and developed a novel series of diamagnetic CAs for Magnetic Resonance Spectroscopic Imaging, a new family of monomeric and dimeric imidazolic derivatives able to provide unambiguous measurements of pH e , independent of water relaxivity, diffusion or exchange

  20. Chemistry of paramagnetic and diamagnetic contrast agents for Magnetic Resonance Imaging and Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Mayoral, Elena [Laboratorio de Sintesis Organica e Imagen Molecular por Resonancia Magnetica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid (Spain); Departamento de Quimica Inorganica y Quimica Tecnica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid (Spain); Negri, Viviana; Soler-Padros, Jordi [Laboratorio de Sintesis Organica e Imagen Molecular por Resonancia Magnetica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid (Spain); Cerdan, Sebastian [Laboratorio de Imagen Espectroscopica por Resonancia Magnetica (LIERM), Instituto de Investigaciones Biomedicas ' Alberto Sols' , CSIC/UAM, c/Arturo Duperier 4, E-28029 Madrid (Spain); Ballesteros, Paloma [Laboratorio de Sintesis Organica e Imagen Molecular por Resonancia Magnetica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid (Spain)], E-mail: pballesteros@ccia.uned.es

    2008-09-15

    We provide a brief overview of the chemistry and most relevant properties of paramagnetic and diamagnetic contrast agents (CAs) for Magnetic Resonance Imaging and Magnetic Resonance Spectroscopic Imaging. Paramagnetic CAs for MRI consist mainly of Gd(III) complexes from linear or macrocyclic polyaminopolycarboxylates. These agents reduce, the relaxation times T{sub 1} and T{sub 2} of the water protons in a concentration dependent manner, increasing selectively MRI contrast in those regions in which they accumulate. In most instances they provide anatomical information on the localization of lesions and in some specific cases they may allow to estimate some physiological properties of tissues including mainly vascular performance. Because of its ability to discriminate easily between normal and diseased tissue, extracellular pH (pH{sub e}) has been added recently, to the battery of variables amenable to MRI investigation. A variety of Gd(III) containing macrocycles sensitive to pH, endogenous or exogenous polypeptides or even liposomes have been investigated for this purpose, using the pH dependence of their relaxivity or magnetization transfer rate constant (chemical exchange saturation transfer, CEST). Many environmental circumstances in addition to pH affect, however, relaxivity or magnetization transfer rate constants of these agents, making the results of pH measurements by MRI difficult to interpret. To overcome these limitations, our laboratory synthesized and developed a novel series of diamagnetic CAs for Magnetic Resonance Spectroscopic Imaging, a new family of monomeric and dimeric imidazolic derivatives able to provide unambiguous measurements of pH{sub e}, independent of water relaxivity, diffusion or exchange.

  1. Liquid-Metal/Water Direct Contact Heat Exchange: Flow Visualization, Flow Stability, and Heat Transfer Using Real-Time X-Ray Imaging

    International Nuclear Information System (INIS)

    Abdulla, Sherif H.; Liu Xin; Anderson, Mark H.; Bonazza, Riccardo; Corradini, Michael L.; Cho, Dae; Page, Richard

    2005-01-01

    Advanced reactor system designs are being considered with liquid-metal cooling connected to a steam power cycle. In addition, current reactor safety systems are considering auxiliary cooling schemes that assure ex-vessel debris coolability utilizing direct water injection into molten material pools to achieve core quenching and eventual coolability. The phenomenon common in both applications is direct contact heat exchange. The current study focuses on detailed measurements of liquid-metal/water direct contact heat exchange that is directly applicable to improvements in effective heat transfer in devices that are being considered for both of these purposes.In this study, a test facility was designed at the University of Wisconsin-Madison to map the operating range of liquid-metal/water direct contact heat exchange. The test section (184-cm height, 45.75-cm width, and 10-cm depth) is a rectangular slice of a larger heat exchange device. This apparatus was used not only to provide measurements of integral thermal performance (i.e., volumetric heat transfer coefficient), but also local heat transfer coefficients in a bubbly flow regime with X-ray imaging based on measured parameters such as bubble formation time, bubble rise velocity, and bubble diameters.To determine these local heat transfer coefficients, a complete methodology of the X-ray radiography for two-phase flow measurement has been developed. With this methodology, a high-energy X-ray imaging system is optimized for our heat exchange experiments. With this real-time, large-area, high-energy X-ray imaging system, the two-phase flow was quantitatively visualized. An efficient image processing strategy was developed by combining several optimal digital image-processing algorithms into a software computational tool written in MATLAB called T-XIP. Time-dependent heat transfer-related variables such as bubble volumes and velocities, were determined. Finally, an error analysis associated with these measurements

  2. Magnetization transfer contrast imaging detects early white matter changes in the APP/PS1 amyloidosis mouse model

    Directory of Open Access Journals (Sweden)

    Jelle Praet

    2016-01-01

    Full Text Available While no definitive cure for Alzheimer's disease exists yet, currently available treatments would benefit greatly from an earlier diagnosis. It has previously been shown that Magnetization transfer contrast (MTC imaging is able to detect amyloid β plaques in old APP/PS1 mice. In the current study we investigated if MTC is also able to visualize early amyloid β (Aβ induced pathological changes. In a cross-sectional study, a comparison was made between the MT ratio of wild type (WT and APP/PS1 mice at 2, 4, 6, 8 and 24 months of age. We observed an increased MT-ratio in the cortex of 24 month old APP/PS1 mice as compared to WT mice. However, when comparing the MT-ratio of the cortex of WT mice with the MT-ratio of the APP/PS1 mice at 2, 4, 6 or 8 months of age, no significant changes could be observed. In contrast to the cortex, we consistently observed a decreased MT-ratio in the splenium of 4, 6 and 8 month old APP/PS1 mice as compared to age-matched WT mice. Lastly, the decreased MT-ratio in the splenium of APP/PS1 mice correlated to the Aβ plaque deposition, astrogliosis and microgliosis. This MT-ratio decrease did however not correlate to the myelin content. Combined, our results suggest that MTC is able to visualize early Aβ-induced changes in the splenium but not the cortex of APP/PS1 mice.

  3. Use of transfer learning to detect diffuse degenerative hepatic diseases from ultrasound images in dogs: A methodological study.

    Science.gov (United States)

    Banzato, T; Bonsembiante, F; Aresu, L; Gelain, M E; Burti, S; Zotti, A

    2018-03-01

    The aim of this methodological study was to develop a deep convolutional neural network (DNN) to detect degenerative hepatic disease from ultrasound images of the liver in dogs and to compare the diagnostic accuracy of the newly developed DNN with that of serum biochemistry and cytology on the same samples, using histopathology as a standard. Dogs with suspected hepatic disease that had no prior history of neoplastic disease, no hepatic nodular pathology, no ascites and ultrasonography performed 24h prior to death were included in the study (n=52). Ultrasonography and serum biochemistry were performed as part of the routine clinical evaluation. On the basis of histopathology, dogs were categorised as 'normal' (n=8), or having 'vascular abnormalities'(n=8), or 'inflammatory'(n=0), 'neoplastic' (n=4) or 'degenerative'(n=32) disease; dogs with 'neoplastic' disease were excluded from further analysis. On cytological evaluation, dogs were categorised as 'normal' (n=11), or having 'inflammatory' (n=0), 'neoplastic' (n=4) or 'degenerative' (n=37) disease. Dogs were categorised as having 'degenerative' (n=32) or 'non-degenerative' (n=16) liver disease for analysis due to the limited sample size. The DNN was developed using a transfer learning methodology on a pre-trained neural network that was retrained and fine-tuned to our data set. The resultant DNN had a high diagnostic accuracy for degenerative liver disease (area under the curve 0.91; sensitivity 100%; specificity 82.8%). Cytology and serum biochemical markers (alanine transaminase and aspartate transaminase) had poor diagnostic accuracy in the detection of degenerative liver disease. The DNN outperformed all the other non-invasive diagnostic tests in the detection of degenerative liver disease. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Optimization of CMOS image sensor utilizing variable temporal multisampling partial transfer technique to achieve full-frame high dynamic range with superior low light and stop motion capability

    Science.gov (United States)

    Kabir, Salman; Smith, Craig; Armstrong, Frank; Barnard, Gerrit; Schneider, Alex; Guidash, Michael; Vogelsang, Thomas; Endsley, Jay

    2018-03-01

    Differential binary pixel technology is a threshold-based timing, readout, and image reconstruction method that utilizes the subframe partial charge transfer technique in a standard four-transistor (4T) pixel CMOS image sensor to achieve a high dynamic range video with stop motion. This technology improves low light signal-to-noise ratio (SNR) by up to 21 dB. The method is verified in silicon using a Taiwan Semiconductor Manufacturing Company's 65 nm 1.1 μm pixel technology 1 megapixel test chip array and is compared with a traditional 4 × oversampling technique using full charge transfer to show low light SNR superiority of the presented technology.

  5. Highly sensitive and area-efficient CMOS image sensor using a PMOSFET-type photodetector with a built-in transfer gate

    Science.gov (United States)

    Seo, Sang-Ho; Kim, Kyoung-Do; Kong, Jae-Sung; Shin, Jang-Kyoo; Choi, Pyung

    2007-02-01

    In this paper, a new CMOS image sensor is presented, which uses a PMOSFET-type photodetector with a transfer gate that has a high and variable sensitivity. The proposed CMOS image sensor has been fabricated using a 0.35 μm 2-poly 4- metal standard CMOS technology and is composed of a 256 × 256 array of 7.05 × 7.10 μm pixels. The unit pixel has a configuration of a pseudo 3-transistor active pixel sensor (APS) with the PMOSFET-type photodetector with a transfer gate, which has a function of conventional 4-transistor APS. The generated photocurrent is controlled by the transfer gate of the PMOSFET-type photodetector. The maximum responsivity of the photodetector is larger than 1.0 × 10 3 A/W without any optical lens. Fabricated 256 × 256 CMOS image sensor exhibits a good response to low-level illumination as low as 5 lux.

  6. Amide proton transfer (APT) imaging of brain tumors at 7 T : The role of tissue water T1 -Relaxation properties

    NARCIS (Netherlands)

    Khlebnikov, V; Polders, Daniel; Hendrikse, J; Robe, Pierre A.; Voormolen, Eduard H; Luijten, Peter R; Klomp, DWJ; Hoogduin, Hans

    PURPOSE: To provide insight into the effect of water T1 relaxation (T1wat ) on amide proton transfer (APT) contrast in tumors. Three different metrics of APT contrast-magnetization transfer ratio (MTRRex ), relaxation-compensated MTRRex (AREX), and traditional asymmetry (MTRasym )-were compared in

  7. Measurement of the modulation transfer function of a charge-coupled device array by the combination of the self-imaging effect and slanted edge method.

    Science.gov (United States)

    Najafi, Sedigheh; Madanipour, Khosro

    2013-07-01

    In this paper, by a combination of the self-imaging effect for Ronchi gratings and the standard slanted edge modulation transfer function (MTF) measurement method for CCD cameras, the MTF of the CCD array without optics is measured. For this purpose, a Ronchi-type grating is illuminated by an expanded He-Ne laser. A self-image of the grating appears without optics on the CCD array that is located on the Talbot distance. The lines of the self-image of the grating are used as a slanted edge array. This method has all the advantages of the slanted edge method, and also since the array of the edge is ready, the total area of the CCD can be tested. The measured MTF is related to the CCD array without optics.

  8. Concept of contrast transfer function for edge illumination x-ray phase-contrast imaging and its comparison with the free-space propagation technique.

    Science.gov (United States)

    Diemoz, Paul C; Vittoria, Fabio A; Olivo, Alessandro

    2016-05-16

    Previous studies on edge illumination (EI) X-ray phase-contrast imaging (XPCi) have investigated the nature and amplitude of the signal provided by this technique. However, the response of the imaging system to different object spatial frequencies was never explicitly considered and studied. This is required in order to predict the performance of a given EI setup for different classes of objects. To this scope, in the present work we derive analytical expressions for the contrast transfer function of an EI imaging system, using the approximation of near-field regime, and study its dependence upon the main experimental parameters. We then exploit these results to compare the frequency response of an EI system with respect of that of a free-space propagation XPCi one. The results achieved in this work can be useful for predicting the signals obtainable for different types of objects and also as a basis for new retrieval methods.

  9. Dynamic glucose enhanced (DGE) MRI for combined imaging of blood-brain barrier break down and increased blood volume in brain cancer.

    Science.gov (United States)

    Xu, Xiang; Chan, Kannie W Y; Knutsson, Linda; Artemov, Dmitri; Xu, Jiadi; Liu, Guanshu; Kato, Yoshinori; Lal, Bachchu; Laterra, John; McMahon, Michael T; van Zijl, Peter C M

    2015-12-01

    Recently, natural d-glucose was suggested as a potential biodegradable contrast agent. The feasibility of using d-glucose for dynamic perfusion imaging was explored to detect malignant brain tumors based on blood brain barrier breakdown. Mice were inoculated orthotopically with human U87-EGFRvIII glioma cells. Time-resolved glucose signal changes were detected using chemical exchange saturation transfer (glucoCEST) MRI. Dynamic glucose enhanced (DGE) MRI was used to measure tissue response to an intravenous bolus of d-glucose. DGE images of mouse brains bearing human glioma showed two times higher and persistent changes in tumor compared with contralateral brain. Area-under-curve (AUC) analysis of DGE delineated blood vessels and tumor and had contrast comparable to the AUC determined using dynamic contrast enhanced (DCE) MRI with GdDTPA, both showing a significantly higher AUC in tumor than in brain (P blood volume and permeability with respect to normal brain. We expect DGE will provide a low-risk and less expensive alternative to DCE MRI for imaging cancer in vulnerable populations, such as children and patients with renal impairment. © 2015 Wiley Periodicals, Inc.

  10. Dynamic Glucose Enhanced (DGE) MRI for Combined Imaging of Blood Brain Barrier Break Down and Increased Blood Volume in Brain Cancer

    Science.gov (United States)

    Xu, Xiang; Chan, Kannie WY; Knutsson, Linda; Artemov, Dmitri; Xu, Jiadi; Liu, Guanshu; Kato, Yoshinori; Lal, Bachchu; Laterra, John; McMahon, Michael T.; van Zijl, Peter C.M.

    2015-01-01

    Purpose Recently, natural d-glucose was suggested as a potential biodegradable contrast agent. The feasibility of using d-glucose for dynamic perfusion imaging was explored to detect malignant brain tumors based on blood brain barrier breakdown. Methods Mice were inoculated orthotopically with human U87-EGFRvIII glioma cells. Time-resolved glucose signal changes were detected using chemical exchange saturation transfer (glucoCEST) MRI. Dynamic glucose enhanced (DGE) MRI was used to measure tissue response to an intravenous bolus of d-glucose. Results DGE images of mouse brains bearing human glioma showed two times higher and persistent changes in tumor compared to contralateral brain. Area-under-curve (AUC) analysis of DGE delineated blood vessels and tumor and had contrast comparable to the AUC determined using dynamic contrast enhanced (DCE) MRI with GdDTPA, both showing a significantly higher AUC in tumor than in brain (pblood volume and permeability with respect to normal brain. We expect DGE will provide a low-risk and less expensive alternative to DCE MRI for imaging cancer in vulnerable populations, such as children and patients with renal impairment. PMID:26404120

  11. Amide proton transfer imaging to discriminate between low- and high-grade gliomas: added value to apparent diffusion coefficient and relative cerebral blood volume

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yoon Seong; Ahn, Sung Soo; Lee, Seung-Koo [Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, College of Medicine, Seoul (Korea, Republic of); Chang, Jong Hee; Kang, Seok-Gu [Yonsei University College of Medicine, Department of Neurosurgery, Seoul (Korea, Republic of); Kim, Se Hoon [Yonsei University College of Medicine, Department of Pathology, Seoul (Korea, Republic of); Zhou, Jinyuan [Johns Hopkins University School of Medicine, Division of MRI Research, Department of Radiology, Baltimore, MD (United States)

    2017-08-15

    To evaluate the added value of amide proton transfer (APT) imaging to the apparent diffusion coefficient (ADC) from diffusion tensor imaging (DTI) and the relative cerebral blood volume (rCBV) from perfusion magnetic resonance imaging (MRI) for discriminating between high- and low-grade gliomas. Forty-six consecutive adult patients with diffuse gliomas who underwent preoperative APT imaging, DTI and perfusion MRI were enrolled. APT signals were compared according to the World Health Organization grade. The diagnostic ability and added value of the APT signal to the ADC and rCBV for discriminating between low- and high-grade gliomas were evaluated using receiver operating characteristic (ROC) analyses and integrated discrimination improvement. The APT signal increased as the glioma grade increased. The discrimination abilities of the APT, ADC and rCBV values were not significantly different. Using both the APT signal and ADC significantly improved discrimination vs. the ADC alone (area under the ROC curve [AUC], 0.888 vs. 0.910; P = 0.007), whereas using both the APT signal and rCBV did not improve discrimination vs. the rCBV alone (AUC, 0.927 vs. 0.923; P = 0.222). APT imaging may be a useful imaging biomarker that adds value to the ADC for discriminating between low- and high-grade gliomas. (orig.)

  12. Paul Lecoq assembles a read head made with special crystals for a PET (positron emission tomography) scanner. He is the initiator of the Crystal Clear collaboration, which aims to transfer crystals developed at CERN to applications in medical imaging.

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    Paul Lecoq assembles a read head made with special crystals for a PET (positron emission tomography) scanner. He is the initiator of the Crystal Clear collaboration, which aims to transfer crystals developed at CERN to applications in medical imaging.

  13. Characterization of membrane protein interactions in plasma membrane derived vesicles with quantitative imaging Förster resonance energy transfer.

    Science.gov (United States)

    Sarabipour, Sarvenaz; Del Piccolo, Nuala; Hristova, Kalina

    2015-08-18

    Here we describe an experimental tool, termed quantitative imaging Förster resonance energy transfer (QI-FRET), that enables the quantitative characterization of membrane protein interactions. The QI-FRET methodology allows us to acquire binding curves and calculate association constants for complex membrane proteins in the native plasma membrane environment. The method utilizes FRET detection, and thus requires that the proteins of interest are labeled with florescent proteins, either FRET donors or FRET acceptors. Since plasma membranes of cells have complex topologies precluding the acquisition of two-dimensional binding curves, the FRET measurements are performed in plasma membrane derived vesicles that bud off cells as a result of chemical or osmotic stress. The results overviewed here are acquired in vesicles produced with an osmotic vesiculation buffer developed in our laboratory, which does not utilize harsh chemicals. The concentrations of the donor-labeled and the acceptor-labeled proteins are determined, along with the FRET efficiencies, in each vesicle. The experiments utilize transient transfection, such that a wide variety of concentrations is sampled. Then, data from hundreds of vesicles are combined to yield dimerization curves. Here we discuss recent findings about the dimerization of receptor tyrosine kinases (RTKs), membrane proteins that control cell growth and differentiation via lateral dimerization in the plasma membrane. We focus on the dimerization of fibroblast growth factor receptor 3 (FGFR3), a RTK that plays a critically important role in skeletal development. We study the role of different FGFR3 domains in FGFR3 dimerization in the absence of ligand, and we show that FGFR3 extracellular domains inhibit unliganded dimerization, while contacts between the juxtamembrane domains, which connect the transmembrane domains to the kinase domains, stabilize the unliganded FGFR3 dimers. Since FGFR3 has been documented to harbor many pathogenic

  14. Not-so-supervised: a survey of semi-supervised, multi-instance, and transfer learning in medical image analysis

    NARCIS (Netherlands)

    Cheplygina, Veronika; de Bruijne, Marleen; Pluim, Josien P. W.

    2018-01-01

    Machine learning (ML) algorithms have made a tremendous impact in the field of medical imaging. While medical imaging datasets have been growing in size, a challenge for supervised ML algorithms that is frequently mentioned is the lack of annotated data. As a result, various methods which can learn

  15. Antibody responses to allergen Lol pIV are suppressed following adoptive transfer of B lymphocytes from the internal image anti-idiotypic antibody-treated mice.

    Science.gov (United States)

    Zhou, E M; Kisil, F T

    1995-10-01

    An internal image anti-idiotypic antibody, designated B1/1, was generated against an idiotope (Id91) of the monoclonal antibody (mAb91) specific for Lol pIV. The administration of B1/1 in PBS, at doses ranging from 100 ng to 100 micrograms/mouse, to syngeneic Balb/c mice resulted in the suppression of the formation of anti-Lol pIV antibodies that possessed the Id91. Spleen cells obtained from the mice 2 weeks after the treatment with B1/1 (25 micrograms/mouse) were adoptively transferred intravenously into the syngeneic recipients which were challenged intraperitoneally with Lol pIV in alum 2 hr after the transfer. The recipients were boosted with Lol pIV 14 days later. It was demonstrated that the transfer of splenic B cells (but not of T cells) from B1/1-treated donors induced a significant suppression of not only the level of IgE and IgG antibodies to Lol pIV, but also the level of antibodies possessing the Id91. Treatment of the B cells with mAb91 plus complement abrogated their ability to transfer the suppression. This study indicates that the treatment with the anti-Id B1/1 generated B cells that were characterized, serologically, as possessing the anti-Id-like antibodies on their surface and were responsible for transferring the suppression of the formation of antibodies to allergen Lol pIV and the expression of Id91.

  16. ADMultiImg: a novel missing modality transfer learning based CAD system for diagnosis of MCI due to AD using incomplete multi-modality imaging data

    Science.gov (United States)

    Liu, Xiaonan; Chen, Kewei; Wu, Teresa; Weidman, David; Lure, Fleming; Li, Jing

    2018-02-01

    Alzheimer's Disease (AD) is the most common cause of dementia and currently has no cure. Treatments targeting early stages of AD such as Mild Cognitive Impairment (MCI) may be most effective to deaccelerate AD, thus attracting increasing attention. However, MCI has substantial heterogeneity in that it can be caused by various underlying conditions, not only AD. To detect MCI due to AD, NIA-AA published updated consensus criteria in 2011, in which the use of multi-modality images was highlighted as one of the most promising methods. It is of great interest to develop a CAD system based on automatic, quantitative analysis of multi-modality images and machine learning algorithms to help physicians more adequately diagnose MCI due to AD. The challenge, however, is that multi-modality images are not universally available for many patients due to cost, access, safety, and lack of consent. We developed a novel Missing Modality Transfer Learning (MMTL) algorithm capable of utilizing whatever imaging modalities are available for an MCI patient to diagnose the patient's likelihood of MCI due to AD. Furthermore, we integrated MMTL with radiomics steps including image processing, feature extraction, and feature screening, and a post-processing for uncertainty quantification (UQ), and developed a CAD system called "ADMultiImg" to assist clinical diagnosis of MCI due to AD using multi-modality images together with patient demographic and genetic information. Tested on ADNI date, our system can generate a diagnosis with high accuracy even for patients with only partially available image modalities (AUC=0.94), and therefore may have broad clinical utility.

  17. Bimonthly assessment of magnetization transfer magnetic resonance imaging parameters in multiple sclerosis: a 14-month, multicentre, follow-up study

    NARCIS (Netherlands)

    Mesaros, S.; Rocca, M.A.; Sormani, M.P.; Valsasina, P.; Markowitz, C.; De Stefano, N.; Montalban, X.; Barkhof, F.; Ranjeva, J.P.; Sailer, M.; Kappos, L.; Comi, G.; Filippi, M.

    2010-01-01

    This study was performed to assess the temporal evolution of damage within lesions and the normal-appearing white matter, measured using frequent magnetization transfer (MT) MRI, in relapsing-remitting multiple sclerosis (RRMS). The relationship of MT ratio (MTR) changes with measures of lesion

  18. "Invisible" conformers of an antifungal disulfide protein revealed by constrained cold and heat unfolding, CEST-NMR experiments, and molecular dynamics calculations.

    Science.gov (United States)

    Fizil, Ádám; Gáspári, Zoltán; Barna, Terézia; Marx, Florentine; Batta, Gyula

    2015-03-23

    Transition between conformational states in proteins is being recognized as a possible key factor of function. In support of this, hidden dynamic NMR structures were detected in several cases up to populations of a few percent. Here, we show by two- and three-state analysis of thermal unfolding, that the population of hidden states may weight 20-40 % at 298 K in a disulfide-rich protein. In addition, sensitive (15) N-CEST NMR experiments identified a low populated (0.15 %) state that was in slow exchange with the folded PAF protein. Remarkably, other techniques failed to identify the rest of the NMR "dark matter". Comparison of the temperature dependence of chemical shifts from experiments and molecular dynamics calculations suggests that hidden conformers of PAF differ in the loop and terminal regions and are most similar in the evolutionary conserved core. Our observations point to the existence of a complex conformational landscape with multiple conformational states in dynamic equilibrium, with diverse exchange rates presumably responsible for the completely hidden nature of a considerable fraction. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

  19. “Invisible” Conformers of an Antifungal Disulfide Protein Revealed by Constrained Cold and Heat Unfolding, CEST-NMR Experiments, and Molecular Dynamics Calculations

    Science.gov (United States)

    Fizil, Ádám; Gáspári, Zoltán; Barna, Terézia; Marx, Florentine; Batta, Gyula

    2015-01-01

    Transition between conformational states in proteins is being recognized as a possible key factor of function. In support of this, hidden dynamic NMR structures were detected in several cases up to populations of a few percent. Here, we show by two- and three-state analysis of thermal unfolding, that the population of hidden states may weight 20–40 % at 298 K in a disulfide-rich protein. In addition, sensitive 15N-CEST NMR experiments identified a low populated (0.15 %) state that was in slow exchange with the folded PAF protein. Remarkably, other techniques failed to identify the rest of the NMR “dark matter”. Comparison of the temperature dependence of chemical shifts from experiments and molecular dynamics calculations suggests that hidden conformers of PAF differ in the loop and terminal regions and are most similar in the evolutionary conserved core. Our observations point to the existence of a complex conformational landscape with multiple conformational states in dynamic equilibrium, with diverse exchange rates presumably responsible for the completely hidden nature of a considerable fraction. PMID:25676351

  20. Consequences of increased use of computed tomography imaging for trauma patients in rural referring hospitals prior to transfer to a regional trauma centre.

    Science.gov (United States)

    Berkseth, Timothy J; Mathiason, Michelle A; Jafari, Mary Ellen; Cogbill, Thomas H; Patel, Nirav Y

    2014-05-01

    Computed tomography (CT) plays an integral role in the evaluation and management of trauma patients. As the number of referring hospital (RH)-based CT scanners increased, so has their utilization in trauma patients before transfer. We hypothesized that this has resulted in increased time at RH, image duplication, and radiation dose. A retrospective chart review was completed for trauma activations transferred to an ACS-verified Level II Trauma Centre (TC) during two time periods: 2002-2004 (Group 1) and 2006-2008 (Group 2). 2005 data were excluded as this marked the transition period for acquisition of hospital-based CT scanners in RH. Statistical analysis included t test and χ(2) analysis. Pgroup 1 and 514 in group 2. Mean age was greater in group 2 compared to group 1 (40.3 versus 37.4, respectively; P=0.028). There were 115 patients in group 1 versus 202 patients in group 2 who underwent CT imaging at RH (Pgroup 1 had CT scans performed at the TC versus 258 patients in group 2 (Ptime at the RH was similar between the groups (117.1 and 112.3min for group 1 and 2, respectively; P=0.561). However, when comparing patients with and without a pretransfer CT at the RH, the median time at RH was 140 versus 67min, respectively (Pgroup 1 and n=42 in group 2) was not significantly different between the two time periods (P=0.392). Head CTs comprised the majority of duplicate CT imaging in both time periods (82.4% in group 1 and 90.5% in group 2). Mean total estimated radiation dose per patient was not significantly different between the two groups (group 1=8.4mSv versus group 2=7.8mSv; P=0.192). A significant increase in CT imaging at the RH prior to transfer to the TC was observed over the study periods. No associated increases in mean time at the RH, image duplication at TC, total estimated radiation dose per patient, and mortality rate were observed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. La Représentation féminine de la culture et de la tradition dans C'est ...

    African Journals Online (AJOL)

    La définition de Laura Cremonese, essaie de nous donner une image plus claire en parlant de l'écriture qui est combative contre la .... la littérature doit être sensible au temps. Elle soutient que : « Bien que nous .... que le protagoniste, chez Beyala, négocie entre l'espace physique et imaginative, les royaumes du réel et de ...

  2. MR spectroscopy (MRS) and magnetisation transfer imaging (MTI), lesion load and clinical scores in early relapsing remitting multiple sclerosis: a combined cross-sectional and longitudinal study

    Energy Technology Data Exchange (ETDEWEB)

    Bellmann-Strobl, J.; Paul, F.; Aktas, O.; Zipp, F. [Charite - University Medicine Berlin and Max Delbrueck Center for Molecular Medicine, Cecilie Vogt Clinic for Neurology, Berlin (Germany); Stiepani, H.; Bohner, G.; Klingebiel, R. [Charite - University Medicine Berlin, Department of Neuroradiology, Berlin (Germany); Wuerfel, J. [Charite - University Medicine Berlin and Max Delbrueck Center for Molecular Medicine, Cecilie Vogt Clinic for Neurology, Berlin (Germany); University Schleswig-Holstein, Institute of Neuroradiology, Campus Luebeck, Kiel (Germany); Warmuth, C. [Charite - University Medicine Berlin, Department of Radiology, Berlin (Germany); Wandinger, K.P. [Charite - University Medicine Berlin, Department of Neurology, Berlin (Germany)

    2009-08-15

    The purpose of this study was to correlate magnetic resonance imaging (MRI)-based lesion load assessment with clinical disability in early relapsing remitting multiple sclerosis (RRMS). Seventeen untreated patients (ten women, seven men; mean age 33.0{+-}7.9 years) with the initial diagnosis of RRMS were included for cross-sectional as well as longitudinal (24 months) clinical and MRI-based assessment in comparison with age-matched healthy controls. Conventional MR sequences, MR spectroscopy (MRS) and magnetisation transfer imaging (MTI) were performed at 1.5 T. Lesion number and volume, MRS and MTI measurements for lesions and normal appearing white matter (NAWM) were correlated to clinical scores [Expanded Disability Status Scale (EDSS), Multiple Sclerosis Functional Composite (MSFC)] for monitoring disease course after treatment initiation (interferon {beta}-1a). MTI and MRS detected changes [magnetisation transfer ratio (MTR), N-acetylaspartate (NAA)/creatine ratio] in NAWM over time. EDSS and lesional MTR increases correlated throughout the disease course. Average MTR of NAWM raised during the study (p<0.05) and correlated to the MSFC score (r=0.476, p<0.001). At study termination, NAA/creatine ratio of NAWM correlated to the MSFC score (p<0.05). MTI and MRS were useful for initial disease assessment in NAWM. MTI and MRS correlated with clinical scores, indicating potential for monitoring the disease course and gaining new insights into treatment-related effects. (orig.)

  3. MR spectroscopy (MRS) and magnetisation transfer imaging (MTI), lesion load and clinical scores in early relapsing remitting multiple sclerosis: a combined cross-sectional and longitudinal study

    International Nuclear Information System (INIS)

    Bellmann-Strobl, J.; Paul, F.; Aktas, O.; Zipp, F.; Stiepani, H.; Bohner, G.; Klingebiel, R.; Wuerfel, J.; Warmuth, C.; Wandinger, K.P.

    2009-01-01

    The purpose of this study was to correlate magnetic resonance imaging (MRI)-based lesion load assessment with clinical disability in early relapsing remitting multiple sclerosis (RRMS). Seventeen untreated patients (ten women, seven men; mean age 33.0±7.9 years) with the initial diagnosis of RRMS were included for cross-sectional as well as longitudinal (24 months) clinical and MRI-based assessment in comparison with age-matched healthy controls. Conventional MR sequences, MR spectroscopy (MRS) and magnetisation transfer imaging (MTI) were performed at 1.5 T. Lesion number and volume, MRS and MTI measurements for lesions and normal appearing white matter (NAWM) were correlated to clinical scores [Expanded Disability Status Scale (EDSS), Multiple Sclerosis Functional Composite (MSFC)] for monitoring disease course after treatment initiation (interferon β-1a). MTI and MRS detected changes [magnetisation transfer ratio (MTR), N-acetylaspartate (NAA)/creatine ratio] in NAWM over time. EDSS and lesional MTR increases correlated throughout the disease course. Average MTR of NAWM raised during the study (p<0.05) and correlated to the MSFC score (r=0.476, p<0.001). At study termination, NAA/creatine ratio of NAWM correlated to the MSFC score (p<0.05). MTI and MRS were useful for initial disease assessment in NAWM. MTI and MRS correlated with clinical scores, indicating potential for monitoring the disease course and gaining new insights into treatment-related effects. (orig.)

  4. Characteristics of lesional and extra-lesional cortical grey matter in relapsing-remitting and secondary progressive multiple sclerosis: A magnetisation transfer and diffusion tensor imaging study.

    Science.gov (United States)

    Yaldizli, Özgür; Pardini, Matteo; Sethi, Varun; Muhlert, Nils; Liu, Zheng; Tozer, Daniel J; Samson, Rebecca S; Wheeler-Kingshott, Claudia Am; Yousry, Tarek A; Miller, David H; Chard, Declan T

    2016-02-01

    In multiple sclerosis (MS), diffusion tensor and magnetisation transfer imaging are both abnormal in lesional and extra-lesional cortical grey matter, but differences between clinical subtypes and associations with clinical outcomes have only been partly assessed. To compare mean diffusivity, fractional anisotropy and magnetisation transfer ratio (MTR) in cortical grey matter lesions (detected using phase-sensitive inversion recovery (PSIR) imaging) and extra-lesional cortical grey matter, and assess associations with disability in relapse-onset MS. Seventy-two people with MS (46 relapsing-remitting (RR), 26 secondary progressive (SP)) and 36 healthy controls were included in this study. MTR, mean diffusivity and fractional anisotropy were measured in lesional and extra-lesional cortical grey matter. Mean fractional anisotropy was higher and MTR lower in lesional compared with extra-lesional cortical grey matter. In extra-lesional cortical grey matter mean fractional anisotropy and MTR were lower, and mean diffusivity was higher in the MS group compared with controls. Mean MTR was lower and mean diffusivity was higher in lesional and extra-lesional cortical grey matter in SPMS when compared with RRMS. These differences were independent of disease duration. In multivariate analyses, MTR in extra-lesional more so than lesional cortical grey matter was associated with disability. Magnetic resonance abnormalities in lesional and extra-lesional cortical grey matter are greater in SPMS than RRMS. Changes in extra-lesional compared with lesional cortical grey matter are more consistently associated with disability. © The Author(s), 2015.

  5. Flow map and measurement of void fraction and heat transfer coefficient using an image analysis technique for flow boiling of water in a silicon microchannel

    International Nuclear Information System (INIS)

    Singh, S G; Duttagupta, S P; Jain, A; Sridharan, A; Agrawal, Amit

    2009-01-01

    The present work focuses on the generation of the flow regime map for two-phase water flow in microchannels of a hydraulic diameter of 140 µm. An image analysis algorithm has been developed and utilized to obtain the local void fraction. The image processing technique is also employed to identify and estimate the percentage of different flow regimes and heat transfer coefficient, as a function of position, heat flux and mass flow rate. Both void fraction and heat transfer coefficient are found to increase monotonically along the length of the microchannel. At low heat flux and low flow rates, bubbly, slug and annular flow regimes are apparent. However, the flow is predominately annular at high heat flux and high flow rate. A breakup of the flow frequency suggests that the flow is bistable in the annular regime, in that at a fixed location, the flow periodically switches from single-phase liquid to annular and vice versa. Otherwise, the occurrence of three regimes—single-phase liquid, bubbly and slug are observed. These results provide several useful insights about two-phase flow in microchannels besides being of fundamental interest

  6. A mobile app for securely capturing and transferring clinical images to the electronic health record: description and preliminary usability study.

    Science.gov (United States)

    Landman, Adam; Emani, Srinivas; Carlile, Narath; Rosenthal, David I; Semakov, Simon; Pallin, Daniel J; Poon, Eric G

    2015-01-02

    Photographs are important tools to record, track, and communicate clinical findings. Mobile devices with high-resolution cameras are now ubiquitous, giving clinicians the opportunity to capture and share images from the bedside. However, secure and efficient ways to manage and share digital images are lacking. The aim of this study is to describe the implementation of a secure application for capturing and storing clinical images in the electronic health record (EHR), and to describe initial user experiences. We developed CliniCam, a secure Apple iOS (iPhone, iPad) application that allows for user authentication, patient selection, image capture, image annotation, and storage of images as a Portable Document Format (PDF) file in the EHR. We leveraged our organization's enterprise service-oriented architecture to transmit the image file from CliniCam to our enterprise clinical data repository. There is no permanent storage of protected health information on the mobile device. CliniCam also required connection to our organization's secure WiFi network. Resident physicians from emergency medicine, internal medicine, and dermatology used CliniCam in clinical practice for one month. They were then asked to complete a survey on their experience. We analyzed the survey results using descriptive statistics. Twenty-eight physicians participated and 19/28 (68%) completed the survey. Of the respondents who used CliniCam, 89% found it useful or very useful for clinical practice and easy to use, and wanted to continue using the app. Respondents provided constructive feedback on location of the photos in the EHR, preferring to have photos embedded in (or linked to) clinical notes instead of storing them as separate PDFs within the EHR. Some users experienced difficulty with WiFi connectivity which was addressed by enhancing CliniCam to check for connectivity on launch. CliniCam was implemented successfully and found to be easy to use and useful for clinical practice. CliniCam is

  7. Multiparametric and molecular imaging of breast tumors with MRI and PET/MRI; Multiparametrische und molekulare Bildgebung von Brusttumoren mit MRT und PET-MRT

    Energy Technology Data Exchange (ETDEWEB)

    Pinker, K. [Medizinische Universitaet Wien, Universitaetsklinik fuer Radiologie und Nuklearmedizin, Division fuer Molekulare und Gender Bildgebung, Wien (Austria); Memorial Sloan-Kettering Cancer Center, Department of Radiology, Molecular Imaging and Therapy Service, New York (United States); State University of Florida, Department of Scientific Computing in Medicine, Florida (United States); Marino, M.A. [Medizinische Universitaet Wien, Universitaetsklinik fuer Radiologie und Nuklearmedizin, Division fuer Molekulare und Gender Bildgebung, Wien (Austria); Policlinico Universitario G. Martino, University of Messina, Department of Biomedical Sciences and Morphologic and Functional Imaging, Messina (Italy); Meyer-Baese, A. [State University of Florida, Department of Scientific Computing in Medicine, Florida (United States); Helbich, T.H. [Medizinische Universitaet Wien, Universitaetsklinik fuer Radiologie und Nuklearmedizin, Division fuer Molekulare und Gender Bildgebung, Wien (Austria)

    2016-07-15

    Magnetic resonance imaging (MRI) of the breast is an indispensable tool in breast imaging for many indications. Several functional parameters with MRI and positron emission tomography (PET) have been assessed for imaging of breast tumors and their combined application is defined as multiparametric imaging. Available data suggest that multiparametric imaging using different functional MRI and PET parameters can provide detailed information about the hallmarks of cancer and may provide additional specificity. Multiparametric and molecular imaging of the breast comprises established MRI parameters, such as dynamic contrast-enhanced MRI, diffusion-weighted imaging (DWI), MR proton spectroscopy ({sup 1}H-MRSI) as well as combinations of radiological and MRI techniques (e.g. PET/CT and PET/MRI) using radiotracers, such as fluorodeoxyglucose (FDG). Multiparametric and molecular imaging of the breast can be performed at different field-strengths (range 1.5-7 T). Emerging parameters comprise novel promising techniques, such as sodium imaging ({sup 23}Na MRI), phosphorus spectroscopy ({sup 31}P-MRSI), chemical exchange saturation transfer (CEST) imaging, blood oxygen level-dependent (BOLD) and hyperpolarized MRI as well as various specific radiotracers. Multiparametric and molecular imaging has multiple applications in breast imaging. Multiparametric and molecular imaging of the breast is an evolving field that will enable improved detection, characterization, staging and monitoring for personalized medicine in breast cancer. (orig.) [German] Die Magnetresonanztomographie (MRT) der Brust ist ein etabliertes nichtinvasives bildgebendes Verfahren mit vielfaeltigen Indikationen. In den letzten Jahren wurden zahlreiche funktionelle MRT- und Positronenemissionstomographie(PET)-Parameter in der Brustbildgebung evaluiert, und ihre kombinierte Anwendung ist als multiparametrische Bildgebung definiert. Bisherige Daten legen nahe, dass die multiparametrische Bildgebung mit MRT und PET

  8. A study on the digital image transfer application mass chest X-ray system up-grade

    International Nuclear Information System (INIS)

    Kim, Sun Chil; Park, Jong Sam; Lee, Jon Il

    2003-01-01

    By converting movable indirect mass chest X-ray devices for vehicles into digital systems and upgrading it to share information with the hospital's medical image information system, excellencies have been confirmed as a result of installing and running this type of system and are listed hereinafter. Upgrading analog systems, such as indirect mass chest X-ray devices dependent on printed film, to digital systems allows them to be run and managed much more efficiently, contributing to the increase in the stability and the efficiency of the system. Unlike existing images, communication based on DICOM standards allow images to be compatible with the hospital's outer and inner network PACS systems, extending the scope of the radiation departments information system. Assuming chest-exclusive indirect mass chest X-rays, a linked development of CAD (Computer Aided Diagnosis, Detector) becomes possible. By applying wireless Internet, Web-PACS for movable indirect mass chest X-ray devices for vehicles will become possible. Research in these fields must continue and if the superior image quality and convenience of digital systems are confirmed, I believe that the conversion of systems still dependent on analog images to modernized digital systems is a must

  9. TRANSFERENCE BEFORE TRANSFERENCE.

    Science.gov (United States)

    Bonaminio, Vincenzo

    2017-10-01

    This paper is predominantly a clinical presentation that describes the transmigration of one patient's transference to another, with the analyst functioning as a sort of transponder. It involves an apparently accidental episode in which there was an unconscious intersection between two patients. The author's aim is to show how transference from one case may affect transference in another, a phenomenon the author calls transference before transference. The author believes that this idea may serve as a tool for understanding the unconscious work that takes place in the clinical situation. In a clinical example, the analyst finds himself caught up in an enactment involving two patients in which he becomes the medium of what happens in session. © 2017 The Psychoanalytic Quarterly, Inc.

  10. Traduire C'est Trahir—Peut-être: Ricoeur and Derrida on the (InFidelity of Translation

    Directory of Open Access Journals (Sweden)

    B. Keith Putt

    2015-07-01

    Full Text Available Paul Ricoeur and Jacques Derrida agree that translation is a tensive activity oscillating between the possible and the impossible with reference to the transposition of meaning among diverse systems of discourse. Both acknowledge that risk, alterity, and plurality accompany every attempt at paraphrasing language “in other words.” Consequently, their positions adhere to the traditional adage that “the translator is a traitor,” precisely because something is always lost in the semantic transfer. Yet, Derrida notes an important disagreement between their respective approaches to translation and accuses Ricoeur of harboring a nostalgia for unitive meaning and of promoting the possibility of a transcendental signified that could produce a “pure” translation. In this essay, I critique Derrida’s interpretation of Ricoeur specifically by examining their individual interpretations of the Tower of Babel myth. I argue that Ricoeur’s theory of Babel as a non-punitive celebration of diversity and the open play of meaning “out-deconstructs” Derrida’s own notion of dissemination.

  11. Non-arteritic anterior ischaemic optic neuropathy: evaluation of the brain and optic pathway by conventional MRI and magnetisation transfer imaging

    Energy Technology Data Exchange (ETDEWEB)

    Argyropoulou, Maria I.; Zikou, Anastasia K.; Tzovara, Ioanna; Margariti, Persefoni [University of Ioannina, Department of Radiology, Medical School, Ioannina (Greece); Nikas, Alexios; Asproudis, Ioannis [University of Ioannina, Ophthalmologic Clinic, Medical School, Ioannina (Greece); Blekas, Kostandinos; Galatsanos, Nikolaos [University of Ioannina, Department of Informatics, Ioannina (Greece)

    2007-07-15

    The purpose of the study was to examine the brain and the visual pathway of patients with non-arteritic anterior ischaemic optic neuropathy (NAION) by using conventional MRI (cMRI) and volumetric magnetisation transfer imaging (MTI). Thirty NAION patients, aged 67.5 {+-} 8.14 years, and 28 age- and gender-matched controls were studied. MTI was used to measure the magnetisation transfer ratio (MTR) of the chiasm and for MTR histograms of the brain. The presence of areas of white matter hyperintensity (WMH) was evaluated on fluid-attenuated inversion recovery (FLAIR) images. Area of the optic nerves (ONs) and volume of the chiasm were assessed, as were coronal short-tau inversion recovery (STIR) and MTI images, respectively. More areas of WMH were observed in patients (total 419; mean 14.4; SD 19) than in controls (total 127; mean 4.7; SD 5.7), P < 0.001. Area (in square millimetres) of the affected ONs, volume(in cubic millimetres) and MTR (in percent) of the chiasm (10.7 {+-} 4.6), (75.8 {+-} 20.2), (56.4 {+-} 6.5), respectively, were lower in patients than in controls (13.6 {+-} 4.3), (158.2 {+-} 75.3) (62.1 {+-} 6.2), respectively, P < 0.05. Mean MTR of brain histograms was lower in patients (53.0 {+-} 8.0) than in controls (58.0 {+-} 5.6), P < 0.05. NAION is characterised by decreased ON and chiasmatic size. The low MTR of the chiasm and brain associated with increased areas of WMH may be suggestive of demyelination and axonal damage due to generalised cerebral vascular disease. (orig.)

  12. Non-arteritic anterior ischaemic optic neuropathy: evaluation of the brain and optic pathway by conventional MRI and magnetisation transfer imaging

    International Nuclear Information System (INIS)

    Argyropoulou, Maria I.; Zikou, Anastasia K.; Tzovara, Ioanna; Margariti, Persefoni; Nikas, Alexios; Asproudis, Ioannis; Blekas, Kostandinos; Galatsanos, Nikolaos

    2007-01-01

    The purpose of the study was to examine the brain and the visual pathway of patients with non-arteritic anterior ischaemic optic neuropathy (NAION) by using conventional MRI (cMRI) and volumetric magnetisation transfer imaging (MTI). Thirty NAION patients, aged 67.5 ± 8.14 years, and 28 age- and gender-matched controls were studied. MTI was used to measure the magnetisation transfer ratio (MTR) of the chiasm and for MTR histograms of the brain. The presence of areas of white matter hyperintensity (WMH) was evaluated on fluid-attenuated inversion recovery (FLAIR) images. Area of the optic nerves (ONs) and volume of the chiasm were assessed, as were coronal short-tau inversion recovery (STIR) and MTI images, respectively. More areas of WMH were observed in patients (total 419; mean 14.4; SD 19) than in controls (total 127; mean 4.7; SD 5.7), P < 0.001. Area (in square millimetres) of the affected ONs, volume(in cubic millimetres) and MTR (in percent) of the chiasm (10.7 ± 4.6), (75.8 ± 20.2), (56.4 ± 6.5), respectively, were lower in patients than in controls (13.6 ± 4.3), (158.2 ± 75.3) (62.1 ± 6.2), respectively, P < 0.05. Mean MTR of brain histograms was lower in patients (53.0 ± 8.0) than in controls (58.0 ± 5.6), P < 0.05. NAION is characterised by decreased ON and chiasmatic size. The low MTR of the chiasm and brain associated with increased areas of WMH may be suggestive of demyelination and axonal damage due to generalised cerebral vascular disease. (orig.)

  13. 3D Micro-topography of Transferred Laboratory and Natural Ice Crystal Surfaces Imaged by Cryo and Environmental Scanning Electron Microscopy

    Science.gov (United States)

    Magee, N. B.; Boaggio, K.; Bancroft, L.; Bandamede, M.

    2015-12-01

    Recent work has highlighted micro-scale roughness on the surfaces of ice crystals grown and imaged in-situ within the chambers of environmental scanning electron microscopes (ESEM). These observations appear to align with theoretical and satellite observations that suggest a prevalence of rough ice in cirrus clouds. However, the atmospheric application of the lab observations are indeterminate because the observations have been based only on crystals grown on substrates and in pure-water vapor environments. In this work, we present details and results from the development of a transfer technique which allows natural and lab-grown ice and snow crystals to be captured, preserved, and transferred into the ESEM for 3D imaging. Ice crystals were gathered from 1) natural snow, 2) a balloon-borne cirrus particle capture device, and 3) lab-grown ice crystals from a diffusion chamber. Ice crystals were captured in a pre-conditioned small-volume (~1 cm3) cryo-containment cell. The cell was then sealed closed and transferred to a specially-designed cryogenic dewer (filled with liquid nitrogen or crushed dry ice) for transport to a new Hitachi Field Emission, Variable Pressure SEM (SU-5000). The cryo-cell was then removed from the dewer and quickly placed onto the pre-conditioned cryo transfer stage attached to the ESEM (Quorum 3010T). Quantitative 3D topographical digital elevation models of ice surfaces are reported from SEM for the first time, including a variety of objective measures of statistical surface roughness. The surfaces of the transported crystals clearly exhibit signatures of mesoscopic roughening that are similar to examples of roughness seen in ESEM-grown crystals. For most transported crystals, the habits and crystal edges are more intricate that those observed for ice grown directly on substrates within the ESEM chamber. Portions of some crystals do appear smooth even at magnification greater than 1000x, a rare observation in our ESEM-grown crystals. The

  14. Ratiometric pH Imaging with a CoII2 MRI Probe via CEST Effects of Opposing pH Dependences (Postprint)

    Science.gov (United States)

    2017-10-13

    acid-catalyzed proton exchange, respectively. Importantly, the pH calibration curve is independent of the probe concentration and is identical in...in aqueous solutions containing 50 mM HEPES and 100 mM NaCl buffered at various pH values were acquired using D2O in an inner capillary to lock the...ppm using a presaturation pulse applied for 6 s at a power level (B1) of 24 μT. D2O was placed in an inner capillary within the NMR sample tube to lock

  15. High-resolution confocal imaging of wall ingrowth deposition in plant transfer cells: Semi-quantitative analysis of phloem parenchyma transfer cell development in leaf minor veins of Arabidopsis.

    Science.gov (United States)

    Nguyen, Suong T T; McCurdy, David W

    2015-04-23

    Transfer cells (TCs) are trans-differentiated versions of existing cell types designed to facilitate enhanced membrane transport of nutrients at symplasmic/apoplasmic interfaces. This transport capacity is conferred by intricate wall ingrowths deposited secondarily on the inner face of the primary cell wall, hence promoting the potential trans-membrane flux of solutes and consequently assigning TCs as having key roles in plant growth and productivity. However, TCs are typically positioned deep within tissues and have been studied mostly by electron microscopy. Recent advances in fluorophore labelling of plant cell walls using a modified pseudo-Schiff-propidium iodide (mPS-PI) staining procedure in combination with high-resolution confocal microscopy have allowed visualization of cellular details of individual tissue layers in whole mounts, hence enabling study of tissue and cellular architecture without the need for tissue sectioning. Here we apply a simplified version of the mPS-PI procedure for confocal imaging of cellulose-enriched wall ingrowths in vascular TCs at the whole tissue level. The simplified mPS-PI staining procedure produced high-resolution three-dimensional images of individual cell types in vascular bundles and, importantly, wall ingrowths in phloem parenchyma (PP) TCs in minor veins of Arabidopsis leaves and companion cell TCs in pea. More efficient staining of tissues was obtained by replacing complex clearing procedures with a simple post-fixation bleaching step. We used this modified procedure to survey the presence of PP TCs in other tissues of Arabidopsis including cotyledons, cauline leaves and sepals. This high-resolution imaging enabled us to classify different stages of wall ingrowth development in Arabidopsis leaves, hence enabling semi-quantitative assessment of the extent of wall ingrowth deposition in PP TCs at the whole leaf level. Finally, we conducted a defoliation experiment as an example of using this approach to statistically

  16. Parameters of glucose metabolism and the aging brain: a magnetization transfer imaging study of brain macro- and micro-structure in older adults without diabetes.

    Science.gov (United States)

    Akintola, Abimbola A; van den Berg, Annette; Altmann-Schneider, Irmhild; Jansen, Steffy W; van Buchem, Mark A; Slagboom, P Eline; Westendorp, Rudi G; van Heemst, Diana; van der Grond, Jeroen

    2015-08-01

    Given the concurrent, escalating epidemic of diabetes mellitus and neurodegenerative diseases, two age-related disorders, we aimed to understand the relation between parameters of glucose metabolism and indices of pathology in the aging brain. From the Leiden Longevity Study, 132 participants (mean age 66 years) underwent a 2-h oral glucose tolerance test to assess glucose tolerance (fasted and area under the curve (AUC) glucose), insulin sensitivity (fasted and AUC insulin and homeostatic model assessment of insulin sensitivity (HOMA-IS)) and insulin secretion (insulinogenic index). 3-T brain MRI was used to detect macro-structural damage (atrophy, white matter hyper-intensities, infarcts and/or micro-bleeds) and magnetization transfer imaging (MTI) to detect loss of micro-structural homogeneity that remains otherwise invisible on conventional MRI. Macro-structurally, higher fasted glucose was significantly associated with white matter atrophy (P = 0.028). Micro-structurally, decreased magnetization transfer ratio (MTR) peak height in gray matter was associated with higher fasted insulin (P = 0.010), AUCinsulin (P = 0.001), insulinogenic index (P = 0.008) and lower HOMA-IS index (P glucose was associated with macro-structural damage, impaired insulin action was associated more strongly with reduced micro-structural brain parenchymal homogeneity. These findings offer some insight into the association between different parameters of glucose metabolism (impairment of which is characteristic of diabetes mellitus) and brain aging.

  17. Imaging of activated caspase-3 in living cell by fluorescence resonance energy transfer during photosensitization-induced apoptosis

    Science.gov (United States)

    Wu, Yunxia; Xing, Da; Chen, Qun; Tang, Yonghong

    2005-01-01

    Photodynamic therapy (PDT) is a novel and promising cancer treatment that employs a combination of a photosensitizing chemical and visible light, induces apoptosis in cell, and activation of caspase-3 is considered to be the final step in many apoptosis pathways. The changes of caspase-3 activation in cell during TNFα- and photodynamic therapy-induced apoptosis was measured by fluorescence resonance energy transfer (FRET) analysis. FRET probe consisting of fusions of an enhanced cyan fluorescent protein (ECFP), Venus and a linker peptide containing the caspase-3 cleavage sequence DEVD was utilized. Therefore, activated caspase-3 cleaved the linker peptide of FRET probe and disrupted the FRET signal. Human lung adenocarcinoma cell line (ASTC-a-1) were stably transfected with the plasmid (ECFP-DEVD-Venus) and then were treated by TNF-α and PDT, respectively. Experimental results indicated that caspase-3 activation resulted in cleavage of linker peptide and subsequent disruption of the FRET signal during TNFα- and photodynamic therapy-induced apoptosis, and that the activation of caspase-3 induced by photodynamic therapy was faster than that induce by TNF-α. The study supports that using FRET technique and different recombinant substrates as FRET probes could be used to detect the process of PDT-induced apoptosis and provide a new means to investigate apoptotic mechanism of PDT.

  18. Modelling dust rings in early-type galaxies through a sequence of radiative transfer simulations and 2D image fitting

    Science.gov (United States)

    Bonfini, P.; González-Martín, O.; Fritz, J.; Bitsakis, T.; Bruzual, G.; Sodi, B. Cervantes

    2018-05-01

    A large fraction of early-type galaxies (ETGs) host prominent dust features, and central dust rings are arguably the most interesting among them. We present here `Lord Of The Rings' (LOTR), a new methodology which allows to integrate the extinction by dust rings in a 2D fitting modelling of the surface brightness distribution. Our pipeline acts in two steps, first using the surface fitting software GALFIT to determine the unabsorbed stellar emission, and then adopting the radiative transfer code SKIRT to apply dust extinction. We apply our technique to NGC 4552 and NGC 4494, two nearby ETGs. We show that the extinction by a dust ring can mimic, in a surface brightness profile, a central point source (e.g. an unresolved nuclear stellar cluster or an active galactic nucleus; AGN) superimposed to a `core' (i.e. a central flattening of the stellar light commonly observed in massive ETGs). We discuss how properly accounting for dust features is of paramount importance to derive correct fluxes especially for low luminosity AGNs (LLAGNs). We suggest that the geometries of dust features are strictly connected with how relaxed is the gravitational potential, i.e. with the evolutionary stage of the host galaxy. Additionally, we find hints that the dust mass contained in the ring relates to the AGN activity.

  19. A synchronized particle image velocimetry and infrared thermography technique applied to convective mass transfer in champagne glasses

    Science.gov (United States)

    Beaumont, Fabien; Liger-Belair, Gérard; Bailly, Yannick; Polidori, Guillaume

    2016-05-01

    In champagne glasses, it was recently suggested that ascending bubble-driven flow patterns should be involved in the release of gaseous carbon dioxide (CO2) and volatile organic compounds. A key assumption was that the higher the velocity of the upward bubble-driven flow patterns in the liquid phase, the higher the volume fluxes of gaseous CO2 desorbing from the supersaturated liquid phase. In the present work, simultaneous monitoring of bubble-driven flow patterns within champagne glasses and gaseous CO2 escaping above the champagne surface was performed, through particle image velocimetry and infrared thermography techniques. Two quite emblematic types of champagne drinking vessels were investigated, namely a long-stemmed flute and a wide coupe. The synchronized use of both techniques proved that the cloud of gaseous CO2 escaping above champagne glasses strongly depends on the mixing flow patterns found in the liquid phase below.

  20. Magnetization transfer imaging identifies basal ganglia abnormalities in adult ADHD that are invisible to conventional T1 weighted voxel-based morphometry

    Directory of Open Access Journals (Sweden)

    Arjun Sethi

    2017-01-01

    Full Text Available In childhood, Attention Deficit Hyperactivity Disorder (ADHD is reliably associated with reduced volume of the striatum. In contrast, striatal abnormalities are infrequently detected in voxel-based morphometry (VBM neuroimaging studies of adults with ADHD. This discrepancy has been suggested to reflect normalisation of striatal morphology with age and prolonged treatment of symptoms. If so, this would indicate that while striatal abnormalities are linked to symptom expression in childhood, they cannot explain the persistence of these symptoms in adulthood. However, this may not be case. Instead, we hypothesized that the lack of evidence for striatal abnormalities in adult ADHD may reflect poor sensitivity of typical (T1-weighted neuroimaging to detect subcortical differences. To address this, we acquired both magnetisation transfer (MT saturation maps optimised for subcortical contrast, and conventional T1-weighted images in 30 adults with ADHD and 30 age, IQ, gender and handedness-matched controls. Using VBM of both datasets, we demonstrate volumetric reductions within the left ventral striatum on MT that are not observed on identically pre-processed T1-weighted images from the same participants. Nevertheless, both techniques reported similar sensitivity to cortical abnormalities in the right inferior parietal lobe. Additionally, we show that differences in striatal iron may potentially explain this reduced sensitivity of T1-weighted images in adults. Together, these findings indicate that prior VBM studies reporting no abnormalities in striatal volume in adult ADHD might have been compromised by the methodological insensitivity of T1-weighted VBM to subcortical differences, and that structural abnormalities of the striatum in ADHD do indeed persist into adulthood.

  1. Lower digit symbol substitution score in the oldest old is related to magnetization transfer and diffusion tensor imaging of the white matter.

    Directory of Open Access Journals (Sweden)

    Vijay eVenkatraman

    2011-09-01

    Full Text Available Background: Slowing information processing is common among community-dwelling elderly and it predicts greater mortality and disability risk. Slowing information processing is related to brain macro-structural abnormalities. Specifically, greater global atrophy and greater small vessel disease of the white matter have been associated to slower processing speed. However, community-dwelling elderly with such macro-structural abnormalities can maintain processing speed. The roles of brain micro-structure for slow processing in very old adults living in the community is uncertain, as epidemiological studies relating these brain markers to cognition and in the context of other health characteristics are sparse. Hypothesis: Information processing is cross-sectionally associated with white matter micro-structure independent of overt macro-structural abnormalities and also independent of health related characteristics. Methods: Imaging indices of micro-structure (diffusion tensor imaging, DTI, and magnetization transfer imaging, MTI, macro-structure (white matter hyperintensities, gray matter volume, Digit Symbol Substitution Test (DSST and health characteristics were measured in 272 elderly (mean age 83 years old, 43% men, 40% Black living in the community. Results: The DTI- and MTI-indices of micro-structure from the normal appearing white matter and not from the normal appearing gray matter were associated with DSST score independent of white matter hyperintensities and gray matter volumes. Associations were also independent of age, race, gender, mini-mental score, systolic blood pressure, prevalent myocardial infarction. Interpretation: DTI and MTI indices of normal appearing white matter are indicators of information processing speed in this cohort of very old adults living in the community. Since processing slowing is a potent index of mortality and disability, these indices may serve as biomarkers in prevention or treatment trials of disability.

  2. Momentum transfer Monte Carlo for the simulation of laser speckle imaging and its application in the skin.

    Science.gov (United States)

    Regan, Caitlin; Hayakawa, Carole; Choi, Bernard

    2017-12-01

    Due to its simplicity and low cost, laser speckle imaging (LSI) has achieved widespread use in biomedical applications. However, interpretation of the blood-flow maps remains ambiguous, as LSI enables only limited visualization of vasculature below scattering layers such as the epidermis and skull. Here, we describe a computational model that enables flexible in-silico study of the impact of these factors on LSI measurements. The model uses Monte Carlo methods to simulate light and momentum transport in a heterogeneous tissue geometry. The virtual detectors of the model track several important characteristics of light. This model enables study of LSI aspects that may be difficult or unwieldy to address in an experimental setting, and enables detailed study of the fundamental origins of speckle contrast modulation in tissue-specific geometries. We applied the model to an in-depth exploration of the spectral dependence of speckle contrast signal in the skin, the effects of epidermal melanin content on LSI, and the depth-dependent origins of our signal. We found that LSI of transmitted light allows for a more homogeneous integration of the signal from the entire bulk of the tissue, whereas epi-illumination measurements of contrast are limited to a fraction of the light penetration depth. We quantified the spectral depth dependence of our contrast signal in the skin, and did not observe a statistically significant effect of epidermal melanin on speckle contrast. Finally, we corroborated these simulated results with experimental LSI measurements of flow beneath a thin absorbing layer. The results of this study suggest the use of LSI in the clinic to monitor perfusion in patients with different skin types, or inhomogeneous epidermal melanin distributions.

  3. Cordelia c'est moi

    DEFF Research Database (Denmark)

    Dehs, Jørgen

    1987-01-01

    Kritik af jean Baudrillard's tolkning af Søren Kierkegaad: Forførens dagbog, som den kommer til udtryk i bogen "Forførelse".......Kritik af jean Baudrillard's tolkning af Søren Kierkegaad: Forførens dagbog, som den kommer til udtryk i bogen "Forførelse"....

  4. Live-cell imaging of biothiols via thiol/disulfide exchange to trigger the photoinduced electron transfer of gold-nanodot sensor

    International Nuclear Information System (INIS)

    Liu, Ching-Ping; Wu, Te-Haw; Liu, Chia-Yeh; Lin, Shu-Yi

    2014-01-01

    Highlights: • The ultrasmall size, PAMAM dendrimer-entrapped Au 8 -clusters were synthesized. • Thiol/disulfide exchange with biothiols to release 2-PyT resulted in quenching. • The sensing platform can detect both low and high molecular weight thiols. • Capable of imaging biothiols including protein thiols in living cells. - Abstract: Biothiols have been reported to involve in intracellular redox-homeostasis against oxidative stress. In this study, a highly selective and sensitive fluorescent probe for sensing biothiols is explored by using an ultrasmall gold nanodot (AuND), the dendrimer-entrapped Au 8 -cluster. This strategy relies upon a thiol/disulfide exchange to trigger the fluorescence change through a photoinduced electron transfer (PET) process between the Au 8 -cluster (as an electron donor) and 2-pyridinethiol (2-PyT) (as an electron acceptor) for sensing biothiols. When 2-PyT is released via the cleavage of disulfide bonds by biothiols, the PET process from the Au 8 -cluster to 2-PyT is initiated, resulting in fluorescence quenching. The fluorescence intensity was found to decrease linearly with glutathione (GSH) concentration (0–1500 μM) at physiological relevant levels and the limit of detection for GSH was 15.4 μM. Compared to most nanoparticle-based fluorescent probes that are limited to detect low molecular weight thiols (LMWTs; i.e., GSH and cysteine), the ultrasmall Au 8 -cluster-based probe exhibited less steric hindrance and can be directly applied in selectively and sensitively detecting both LMWTs and high molecular weight thiols (HMWTs; i.e., protein thiols). Based on such sensing platform, the surface-functionalized Au 8 -cluster has significant promise for use as an efficient nanoprobe for intracellular fluorescence imaging of biothiols including protein thiols in living cells whereas other nanoparticle-based fluorescent probes cannot

  5. Live-cell imaging of biothiols via thiol/disulfide exchange to trigger the photoinduced electron transfer of gold-nanodot sensor

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ching-Ping; Wu, Te-Haw; Liu, Chia-Yeh; Lin, Shu-Yi, E-mail: shuyi@nhri.org.tw

    2014-11-07

    Highlights: • The ultrasmall size, PAMAM dendrimer-entrapped Au{sub 8}-clusters were synthesized. • Thiol/disulfide exchange with biothiols to release 2-PyT resulted in quenching. • The sensing platform can detect both low and high molecular weight thiols. • Capable of imaging biothiols including protein thiols in living cells. - Abstract: Biothiols have been reported to involve in intracellular redox-homeostasis against oxidative stress. In this study, a highly selective and sensitive fluorescent probe for sensing biothiols is explored by using an ultrasmall gold nanodot (AuND), the dendrimer-entrapped Au{sub 8}-cluster. This strategy relies upon a thiol/disulfide exchange to trigger the fluorescence change through a photoinduced electron transfer (PET) process between the Au{sub 8}-cluster (as an electron donor) and 2-pyridinethiol (2-PyT) (as an electron acceptor) for sensing biothiols. When 2-PyT is released via the cleavage of disulfide bonds by biothiols, the PET process from the Au{sub 8}-cluster to 2-PyT is initiated, resulting in fluorescence quenching. The fluorescence intensity was found to decrease linearly with glutathione (GSH) concentration (0–1500 μM) at physiological relevant levels and the limit of detection for GSH was 15.4 μM. Compared to most nanoparticle-based fluorescent probes that are limited to detect low molecular weight thiols (LMWTs; i.e., GSH and cysteine), the ultrasmall Au{sub 8}-cluster-based probe exhibited less steric hindrance and can be directly applied in selectively and sensitively detecting both LMWTs and high molecular weight thiols (HMWTs; i.e., protein thiols). Based on such sensing platform, the surface-functionalized Au{sub 8}-cluster has significant promise for use as an efficient nanoprobe for intracellular fluorescence imaging of biothiols including protein thiols in living cells whereas other nanoparticle-based fluorescent probes cannot.

  6. Liposomes and lipid disks traverse the BBB and BBTB as intact forms as revealed by two-step Förster resonance energy transfer imaging

    Directory of Open Access Journals (Sweden)

    Tongcheng Dai

    2018-03-01

    Full Text Available The blood–brain barrier (BBB and the blood–brain tumor barrier (BBTB prevent drug and nano-drug delivery systems from entering the brain. However, ligand-mediated nano-drug delivery systems have significantly enhanced the therapeutic treatment of glioma. In this study we investigated the mechanism especially the integrity of liposomes and lipid disks while traversing the BBB and BBTB both in vitro and in vivo. Fluorophores (DiO, DiI and DiD were loaded into liposomes and lipid disks to form Förster resonance energy transfer (FRET nano-drug delivery systems. Using brain capillary endothelial cells as a BBB model, we show that liposomes and disks are present in the cytoplasm as their intact forms and traverse the BBB with a ratio of 0.68‰ and 1.67‰, respectively. Using human umbilical vein endothelial cells as BBTB model, liposomes and disks remained intact and traversed the BBTB with a ratio of 2.31‰ and 8.32‰ at 3 h. Ex vivo imaging and immunohistochemical results revealed that liposomes and disks could traverse the BBB and BBTB in vivo as intact forms. In conclusion, these observations explain in part the mechanism by which nano-drug delivery systems increase the therapeutic treatment of glioma. KEY WORDS: Liposomes, Disks, Intact form, BBB, BBTB, FRET

  7. Time-resolved imaging and immobilization study of biomaterials on hydrophobic and superhydrophobic surfaces by means of laser-induced forward transfer

    International Nuclear Information System (INIS)

    Boutopoulos, Christos; Chatzipetrou, Marianneza; Zergioti, Ioanna; Papathanasiou, Athanasios G

    2014-01-01

    In this work, we present the generation of high velocity liquid jets of a photosynthetic biomaterial in buffer solution (i.e. thylakoid membranes) and a test solution, using the laser-induced forward transfer (LIFT) technique. The high impact pressure of the collision of the jets on solid substrates, ranging from 0.045 MPa–35 MPa, resulted in strong physical immobilization of the photosynthetic biomaterial on superhydrophobic (SH) poly(methyl methacrylate) (PMMA) surfaces and hydrophobic gold surfaces. The immobilization efficiency was evaluated by fluorescence microscopy, while time-resolved imaging of the LIFT process was carried out to study the corresponding LIFT dynamics. The results show that this simple, direct and chemical-linkers-free immobilization technique is valuable for several biosensors and microfluidic applications since it can be applied to a variety of hydrophobic and SH substrates, leading to the selective immobilization of the biomaterials, due to the high spatial printing resolution of the LIFT technique. (letter)

  8. Characterization of the activity of ultrasound emitted in a perpendicular liquid flow using Particle Image Velocimetry (PIV) and electrochemical mass transfer measurements.

    Science.gov (United States)

    Barthès, Magali; Mazue, Gerald; Bonnet, Dimitri; Viennet, Remy; Hihn, Jean-Yves; Bailly, Yannick

    2015-05-01

    The present work is dedicated to the study of the interactions between a liquid circulation and a perpendicular acoustic wave propagation. A specific experimental setup was designed to study one transducer operating at 20 kHz, with the help of electrochemical mass transfer measurements combined with Particle Image Velocimetry (PIV) determination. Electrodes were located on the wall opposite to the acoustic emission. Experiments were performed for various Reynolds numbers: from 0 to 21700 (different liquid flow rates and viscosities). Both PIV and electrochemical measurements methods were found to be relevant, and had delivered complementary information. Even if PIV showed that the plume due to streaming was highly deflected by the additional flow, electrochemical measurements showed that there was still an activity, higher than in silent conditions, on the wall facing the transducer. Thus the ultrasound contribution remained noticeable on the surface opposite to the transducer even for a disturbed hydrodynamic environment due to the presence of a liquid circulation perpendicular to the wave propagation. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Imaging

    International Nuclear Information System (INIS)

    Kellum, C.D.; Fisher, L.M.; Tegtmeyer, C.J.

    1987-01-01

    This paper examines the advantages of the use of excretory urography for diagnosis. According to the authors, excretory urography remains the basic radiologic examination of the urinary tract and is the foundation for the evaluation of suspected urologic disease. Despite development of the newer diagnostic modalities such as isotope scanning, ultrasonography, CT, and magnetic resonsance imaging (MRI), excretory urography has maintained a prominent role in ruorradiology. Some indications have been altered and will continue to change with the newer imaging modalities, but the initial evaluation of suspected urinary tract structural abnormalities; hematuria, pyuria, and calculus disease is best performed with excretory urography. The examination is relatively inexpensive and simple to perform, with few contraindictions. Excretory urography, when properly performed, can provide valuable information about the renal parenchyma, pelvicalyceal system, ureters, and urinary bladder

  10. Heat transfer

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Heat transfer. Heat conduction in solid slab. Convective heat transfer. Non-linear temperature. variation due to flow. HEAT FLUX AT SURFACE. conduction/diffusion.

  11. Heat transfer

    International Nuclear Information System (INIS)

    Saad, M.A.

    1985-01-01

    Heat transfer takes place between material systems as a result of a temperature difference. The transmission process involves energy conversions governed by the first and second laws of thermodynamics. The heat transfer proceeds from a high-temperature region to a low-temperature region, and because of the finite thermal potential, there is an increase in entropy. Thermodynamics, however, is concerned with equilibrium states, which includes thermal equilibrium, irrespective of the time necessary to attain these equilibrium states. But heat transfer is a result of thermal nonequilibrium conditions, therefore, the laws of thermodynamics alone cannot describe completely the heat transfer process. In practice, most engineering problems are concerned with the rate of heat transfer rather than the quantity of heat being transferred. Resort then is directed to the particular laws governing the transfer of heat. There are three distinct modes of heat transfer: conduction, convection, and radiation. Although these modes are discussed separately, all three types may occur simultaneously

  12. Transfer Pricing

    DEFF Research Database (Denmark)

    Nielsen, Søren Bo

    2014-01-01

    Against a background of rather mixed evidence about transfer pricing practices in multinational enterprises (MNEs) and varying attitudes on the part of tax authorities, this paper explores how multiple aims in transfer pricing can be pursued across four different transfer pricing regimes. A MNE h...

  13. Patterns produced when soil is transferred to bras by placing and dragging actions: The application of digital photography and image processing to support visible observations.

    Science.gov (United States)

    Murray, Kathleen R; Fitzpatrick, Robert W; Bottrill, Ralph; Kobus, Hilton

    2017-07-01

    A series of soil transference experiments (STEs) were undertaken to determine whether patterns identified in laboratory experiments could also be recognised at a simulated crime scene in the field. A clothed 55kg human rescue dummy dressed in a padded bra was either dragged or merely placed on a soil surface at sites with natural and anthropogenic soil types under both wet and dry soil conditions. Transfer patterns produced by dragging compared favourably with those of laboratory experiments. Twelve patterns were identified when a clothed human rescue dummy was dragged across the two soil types in the field. This expanded the original set of eight soil transfer patterns identified from dragging weighted fabric across soil samples in the laboratory. Soil transferred by placing the human rescue dummy resulted in a set of six transfer patterns that were different to those produced by dragging. By comparing trace soil patterns transferred to bras using each transfer method, it was revealed that certain transfer patterns on bras could indicate how the fabric had made contact with a soil surface. A photographic method was developed for crime scene examiners to capture this often subtle soil evidence before a body is transported or the clothing removed. This improved understanding of the dynamics of soil transference to bras and related clothing fabric may assist forensic investigators reconstruct the circumstances of a variety of forensic events. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Transfer Pricing

    DEFF Research Database (Denmark)

    Rohde, Carsten; Rossing, Christian Plesner

    trade internally as the units have to decide what prices should be paid for such inter-unit transfers. One important challenge is to uncover the consequences that different transfer prices have on the willingness in the organizational units to coordinate activities and trade internally. At the same time...... the determination of transfer price will affect the size of the profit or loss in the organizational units and thus have an impact on the evaluation of managers‟ performance. In some instances the determination of transfer prices may lead to a disagreement between coordination of the organizational units...

  15. Targeted Molecular Imaging of Cancer Cells Using MS2-Based 129 Xe NMR

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Keunhong [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Netirojjanakul, Chawita [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Munch, Henrik K. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Sun, Jinny [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Finbloom, Joel A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Wemmer, David E. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Biosciences Division; Pines, Alexander [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Francis, Matthew B. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

    2016-07-25

    Targeted, selective, and highly sensitive 129Xe NMR nanoscale biosensors have been synthesized using a spherical MS2 viral capsid, Cryptophane A molecules, and DNA aptamers. The biosensors showed strong binding specificity toward targeted lymphoma cells (Ramos line). Hyperpolarized 129Xe NMR signal contrast and hyper-CEST 129Xe MRI image contrast indicated its promise as highly sensitive hyperpolarized 129Xe NMR nanoscale biosensor for future applications in cancer detection in vivo.

  16. Thermal transfer recording media

    Science.gov (United States)

    Takei, T.; Taniguchi, M.; Fukushima, H.; Yamaguchi, Y.; Shinozuka, M.; Seikohsha, K. K. Suwa

    1988-08-01

    The recording media consist of more than or one coloring layer and a layer containing a flame retardant to ensure noncombustibility and good thermal transfer. Thus, a PET film was coated on a side with a compound containing Vylon 290 (polyester resin), AFR-1021 (decabromodiphenyl oxide) 8 and Polysafe 60 (Sb oxide), and coated on the other side with a compound containing carnauba wax, HNP-9 (paraffin wax), EV-410 (ethylene-vinyl acetate copolymer), and Cu phthalocyanine to give a thermal transfer recording medium which showed good noncombustibility and antiblocking properties, and provided high quality images.

  17. "Transfer Shock" or "Transfer Ecstasy?"

    Science.gov (United States)

    Nickens, John M.

    The alleged characteristic drop in grade point average (GPA) of transfer students and the subsequent rise in GPA was investigated in this study. No statistically significant difference was found in first term junior year GPA between junior college transfers and native Florida State University students after the variance accounted for by the…

  18. Validation and transferability study of a method based on near-infrared hyperspectral imaging for the detection and quantification of ergot bodies in cereals

    NARCIS (Netherlands)

    Vermeulen, Ph.; Fernández - Pierna, J.A.; Egmond, van H.P.; Zegers, J.; Dardenne, P.; Baeten, V.

    2013-01-01

    In recent years, near-infrared (NIR) hyperspectral imaging has proved its suitability for quality and safety control in the cereal sector by allowing spectroscopic images to be collected at single-kernel level, which is of great interest to cereal control laboratories. Contaminants in cereals

  19. Station Transfers

    Data.gov (United States)

    Department of Homeland Security — ixed rail transit external system transfers for systems within the Continental United States, Alaska, Hawaii, the District of Columbia, and Puerto Rico. The modes of...

  20. Technology transfer

    International Nuclear Information System (INIS)

    1998-01-01

    On the base of technological opportunities and of the environmental target of the various sectors of energy system this paper intend to conjugate the opportunity/objective with economic and social development through technology transfer and information dissemination [it

  1. MR imaging of articular cartilage : comparison of magnetization transfer contrast and fat-suppression in multiplanar and 3D gradient-echo, spin-echo, turbo spin-echo techniques

    International Nuclear Information System (INIS)

    Lee, Young Joon; Joo, Eun Young; Eun, Choong Ki

    1999-01-01

    The purpose of this study was to evaluate the effects of magnetization transfer contrast(MTC) and fat-suppression(FS) in variable spin-echo and gradient-echo sequences for articular cartilage imaging and to determine the optimal pulse sequences. Using variable 7-pulse sequences, the knees of 15 pigs were imaged Axial images were obtained using proton density and T2-weighted spin-echo (PDWSE and T2WSE), turbo spin-echo (TSE), multiplanar gradient-echo (MPGR), and 3D steady-state gradient-echo (3DGRE) sequences, and the same pulse sequences were then repeated using MTC. Also T1-weighted spin-echo(T1WSE) and 3D spoiled gradient-echo(3DSPGR) images of knees were also acquired, and the procedure was repeated using FS. For each knee, a total of 14 axial images were acquired, and using a 6-band scoring system, the visibility of and the visibilities of the the articular cartilage was analyzed. The visual effect of MTC and FS was scored using a 4-band scale. For each image, the signal intensities of articular cartilage, subchondral bone, muscles, and saline were measured, and signal-to-noise ratios(SNR) and contrast-to-noise ratios(CNR) were also calculated. Visibility of the cartilage was best when 3DSPGR and T1WSE sequences were used. MTC imaging increased the negative contrast between cartilage and saline, but FS imaging provided more positive contrast. CNR between cartilage and saline was highest when using TSE with FS(-351.1±15.3), though CNR between cartilage and bone then fell to -14.7±10.8. In MTC imaging using MPGR showed the greatest increase of negative contrast between cartilage and saline(CNR change=-74.7); the next highest was when 3DGRE was used(CNR change=-34.3). CNR between cartilage and bone was highest with MPGR(161.9±17.7), but with MTC, the greatest CNR decrease(-81.8) was observed. The greatest CNR increase between cartilage and bone was noted in T1WSE with FS. In all scans, FS provided a cartilage-only positive contrast image, though the absolute

  2. Unsupervised Typography Transfer

    OpenAIRE

    Sun, Hanfei; Luo, Yiming; Lu, Ziang

    2018-01-01

    Traditional methods in Chinese typography synthesis view characters as an assembly of radicals and strokes, but they rely on manual definition of the key points, which is still time-costing. Some recent work on computer vision proposes a brand new approach: to treat every Chinese character as an independent and inseparable image, so the pre-processing and post-processing of each character can be avoided. Then with a combination of a transfer network and a discriminating network, one typograph...

  3. Probing slowly exchanging protein systems via {sup 13}C{sup {alpha}}-CEST: monitoring folding of the Im7 protein

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Alexandar L.; Bouvignies, Guillaume; Kay, Lewis E., E-mail: kay@pound.med.utoronto.ca [University of Toronto, Departments of Molecular Genetics, Biochemistry and Chemistry (Canada)

    2013-03-15

    A {sup 13}C{sup {alpha}} chemical exchange saturation transfer based experiment is presented for the study of protein systems undergoing slow interconversion between an 'observable' ground state and one or more 'invisible' excited states. Here a labeling strategy whereby [2-{sup 13}C]-glucose is the sole carbon source is exploited, producing proteins with {sup 13}C at the C{sup {alpha}} position, while the majority of residues remain unlabeled at CO or C{sup {beta}}. The new experiment is demonstrated with an application to the folding reaction of the Im7 protein that involves an on-pathway excited state. The obtained excited state {sup 13}C{sup {alpha}} chemical shifts are cross validated by comparison to values extracted from analysis of CPMG relaxation dispersion profiles, establishing the utility of the methodology.

  4. Technology Transfer

    Science.gov (United States)

    Smith, Nanette R.

    1995-01-01

    The objective of this summer's work was to attempt to enhance Technology Application Group (TAG) ability to measure the outcomes of its efforts to transfer NASA technology. By reviewing existing literature, by explaining the economic principles involved in evaluating the economic impact of technology transfer, and by investigating the LaRC processes our William & Mary team has been able to lead this important discussion. In reviewing the existing literature, we identified many of the metrics that are currently being used in the area of technology transfer. Learning about the LaRC technology transfer processes and the metrics currently used to track the transfer process enabled us to compare other R&D facilities to LaRC. We discuss and diagram impacts of technology transfer in the short run and the long run. Significantly, it serves as the basis for analysis and provides guidance in thinking about what the measurement objectives ought to be. By focusing on the SBIR Program, valuable information regarding the strengths and weaknesses of this LaRC program are to be gained. A survey was developed to ask probing questions regarding SBIR contractors' experience with the program. Specifically we are interested in finding out whether the SBIR Program is accomplishing its mission, if the SBIR companies are providing the needed innovations specified by NASA and to what extent those innovations have led to commercial success. We also developed a survey to ask COTR's, who are NASA employees acting as technical advisors to the SBIR contractors, the same type of questions, evaluating the successes and problems with the SBIR Program as they see it. This survey was developed to be implemented interactively on computer. It is our hope that the statistical and econometric studies that can be done on the data collected from all of these sources will provide insight regarding the direction to take in developing systematic evaluations of programs like the SBIR Program so that they can

  5. Video clip transfer of radiological images using a mobile telephone in emergency neurosurgical consultations (3G Multi-Media Messaging Service).

    Science.gov (United States)

    Waran, Vicknes; Bahuri, Nor Faizal Ahmad; Narayanan, Vairavan; Ganesan, Dharmendra; Kadir, Khairul Azmi Abdul

    2012-04-01

    The purpose of this study was to validate and assess the accuracy and usefulness of sending short video clips in 3gp file format of an entire scan series of patients, using mobile telephones running on 3G-MMS technology, to enable consultation between junior doctors in a neurosurgical unit and the consultants on-call after office hours. A total of 56 consecutive patients with acute neurosurgical problems requiring urgent after-hours consultation during a 6-month period, prospectively had their images recorded and transmitted using the above method. The response to the diagnosis and the management plan by two neurosurgeons (who were not on site) based on the images viewed on a mobile telephone were reviewed by an independent observer and scored. In addition to this, a radiologist reviewed the original images directly on the hospital's Patients Archiving and Communication System (PACS) and this was compared with the neurosurgeons' response. Both neurosurgeons involved in this study were in complete agreement with their diagnosis. The radiologist disagreed with the diagnosis in only one patient, giving a kappa coefficient of 0.88, indicating an almost perfect agreement. The use of mobile telephones to transmit MPEG video clips of radiological images is very advantageous for carrying out emergency consultations in neurosurgery. The images accurately reflect the pathology in question, thereby reducing the incidence of medical errors from incorrect diagnosis, which otherwise may just depend on a verbal description.

  6. Technology transfer

    International Nuclear Information System (INIS)

    Boury, C.

    1986-01-01

    This paper emphasizes in the specific areas of design, engineering and component production. This paper presents what Framatome has to offer in these areas and its export oriented philosophy. Then, a typical example of this technology transfer philosophy is the collaboration with the South Korean firm, Korea Heavy Industries Corporation (KHIC) for the supply of KNU 9 and KNU 10 power stations

  7. Pedagogy of the Written Image

    Directory of Open Access Journals (Sweden)

    Jonathan Lahey Dronsfield

    2010-01-01

    Full Text Available "Text, it is Jean-Luc Godard’s “ennemi royal, principal." Text, it is on the side of death, “les images c’est la vie et les textes, c’est la mort”. Twenty years later and the war is not over: “Une image est paisible. Une image de la Vierge avec son petit enfant sur son âne n'amène pas la guerre, c'est son interprétation par un texte qui amènera la guerre et qui fera que les soldats de Luther iront déchirer les toiles de Raphaël.” Godard’s story is not just of the history of cinema, it is one in which text has won out to the extent that TV and the computer too make of the image something subservient to text. “Since Gutenberg” the text has triumphed in this way. “There was a long struggle, marriage or liaison between painting and text. Then the text carried the day. Film is the last art in the pictorial tradition... Take away the text and you’ll see what’s left. In TV nothing is left.” It is obvious from these lines of demarcation, lines which divide the art of the image from what would declare war on its most sacred icons and defeat its technologies, a conflict in which there is just the one aggressor, a division which makes of the relation between image and text nothing less than a matter of life and death, that for Godard text is indeed the enemy..."

  8. Magnetic Resonance Imaging of Liver Metastasis.

    Science.gov (United States)

    Karaosmanoglu, Ali Devrim; Onur, Mehmet Ruhi; Ozmen, Mustafa Nasuh; Akata, Deniz; Karcaaltincaba, Musturay

    2016-12-01

    Liver magnetic resonance imaging (MRI) is becoming the gold standard in liver metastasis detection and treatment response assessment. The most sensitive magnetic resonance sequences are diffusion-weighted images and hepatobiliary phase images after Gd-EOB-DTPA. Peripheral ring enhancement, diffusion restriction, and hypointensity on hepatobiliary phase images are hallmarks of liver metastases. In patients with normal ultrasonography, computed tomography (CT), and positron emission tomography (PET)-CT findings and high clinical suspicion of metastasis, MRI should be performed for diagnosis of unseen metastasis. In melanoma, colon cancer, and neuroendocrine tumor metastases, MRI allows confident diagnosis of treatment-related changes in liver and enables differential diagnosis from primary liver tumors. Focal nodular hyperplasia-like nodules in patients who received platinum-based chemotherapy, hypersteatosis, and focal fat can mimic metastasis. In cancer patients with fatty liver, MRI should be preferred to CT. Although the first-line imaging for metastases is CT, MRI can be used as a problem-solving method. MRI may be used as the first-line method in patients who would undergo curative surgery or metastatectomy. Current limitation of MRI is low sensitivity for metastasis smaller than 3mm. MRI fingerprinting, glucoCEST MRI, and PET-MRI may allow simpler and more sensitive diagnosis of liver metastasis. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Technology transfer

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    Illustrated by the example of the FRG's nuclear energy exports, it is shown that the nuclear technology transfer leads to new dimensions of intergovernmental relations, which hold within themselves on account of multiple state-to-state, scientific, industrial and - last but not least - personal contacts the chance of far-reaching friendships between countries and people. If the chance is taken, this can also be seen as an important contribution towards maintaining the peace. (orig.) [de

  10. Transfer Zymography.

    Science.gov (United States)

    Pan, Daniel; Wilson, Karl A; Tan-Wilson, Anna

    2017-01-01

    The technique described here, transfer zymography, was developed to overcome two limitations of conventional zymography. When proteolytic enzymes are resolved by nonreducing SDS-PAGE into a polyacrylamide gel with copolymerized protein substrate, the presence of the protein substrate can result in anomalous, often slower, migration of the protease and an estimated mass higher than its actual mass. A further drawback is that the presence of a high background of substrate protein interferes with proteomic analysis of the protease band by excision, tryptic digestion, and LC-MS/MS analysis. In transfer zymography, the proteolytic enzymes are resolved by conventional nonreducing SDS-PAGE, without protein substrate in the gel. The proteins in the resolving gel are then electrophoretically transferred to a receiving gel that contains the protein substrate, by a process similar to western blotting. The receiving gel is then processed in a manner similar to conventional zymography. SDS is removed by Triton X-100 and incubated in conditions suitable for the proteolytic activity. After protein staining, followed by destaining, bands representing regions with active protease are visualized as clear bands in a darkly stained background. For proteomic analysis, electrophoresis is carried out simultaneously on a second resolving gel, and the bands corresponding to the clear regions in the receiving gel after zymogram development are excised for proteomic analysis.

  11. Targeted molecular imaging

    International Nuclear Information System (INIS)

    Kim, E. Edmund

    2003-01-01

    Molecular imaging aims to visualize the cellular and molecular processes occurring in living tissues, and for the imaging of specific molecules in vivo, the development of reporter probes and dedicated imaging equipment is most important. Reporter genes can be used to monitor the delivery and magnitude of therapeutic gene transfer, and the time variation involved. Imaging technologies such as micro-PET, SPECT, MRI and CT, as well as optical imaging systems, are able to non-invasively detect, measure, and report the simultaneous expression of multiple meaningful genes. It is believed that recent advances in reporter probes, imaging technologies and gene transfer strategies will enhance the effectiveness of gene therapy trials

  12. Development of rainbow refractometry and out-of-focus imaging to characterize heat and mass transfers in two-phase flow and aerosol collection processes by droplets

    International Nuclear Information System (INIS)

    Lemaitre, Pascal; Porcheron, Emmanuel; Nuboer, Amandine

    2007-01-01

    In order to study the interactions between a spray and an atmosphere representative of a severe accident in a Pressurized Water Reactor, in terms of pressure, temperature and composition (steam and aerosol), the French Institute for Radiological Protection and Nuclear Safety (IRSN) developed the TOSQAN facility. This paper presents the development and qualification of the global rainbow refractometry and Interferometric Laser Imaging for Droplets Sizing (ILIDS) that are respectively dedicated to measure the spray droplets temperature and size. In addition we present an extension of these two techniques in order to determine the aerosol concentration inside the droplet and the aerosol removal rate. (author)

  13. Facilitating Transfers

    DEFF Research Database (Denmark)

    Kjær, Poul F.

    to specific logics of temporalisation and spatial expansion of a diverse set of social processes in relation to, for example, the economy, politics, science and the mass media. On this background, the paper will more concretely develop a conceptual framework for classifying different contextual orders...... that the essential functional and normative purpose of regulatory governance is to facilitate, stabilise and justify the transfer of condensed social components (such as economic capital and products, political decisions, legal judgements, religious beliefs and scientific knowledge) from one social contexts...

  14. Extending roGFP Emission via Förster-Type Resonance Energy Transfer Relay Enables Simultaneous Dual Compartment Ratiometric Redox Imaging in Live Cells.

    Science.gov (United States)

    Norcross, Stevie; Trull, Keelan J; Snaider, Jordan; Doan, Sara; Tat, Kiet; Huang, Libai; Tantama, Mathew

    2017-11-22

    Reactive oxygen species (ROS) mediate both intercellular and intraorganellar signaling, and ROS propagate oxidative stress between cellular compartments such as mitochondria and the cytosol. Each cellular compartment contains its own sources of ROS as well as antioxidant mechanisms, which contribute to dynamic fluctuations in ROS levels that occur during signaling, metabolism, and stress. However, the coupling of redox dynamics between cellular compartments has not been well studied because of the lack of available sensors to simultaneously measure more than one subcellular compartment in the same cell. Currently, the redox-sensitive green fluorescent protein, roGFP, has been used extensively to study compartment-specific redox dynamics because it provides a quantitative ratiometric readout and it is amenable to subcellular targeting as a genetically encoded sensor. Here, we report a new family of genetically encoded fluorescent protein sensors that extend the fluorescence emission of roGFP via Förster-type resonance energy transfer to an acceptor red fluorescent protein for dual-color live-cell microscopy. We characterize the redox and optical properties of the sensor proteins, and we demonstrate that they can be used to simultaneously measure cytosolic and mitochondrial ROS in living cells. Furthermore, we use these sensors to reveal cell-to-cell heterogeneity in redox coupling between the cytosol and mitochondria when neuroblastoma cells are exposed to reductive and metabolic stresses.

  15. Radionuclide transfer

    International Nuclear Information System (INIS)

    Gerber, G.B.

    1993-01-01

    The research project described here had the aim to obtain further information on the transfer of nuclides during pregnancy and lactation. The tests were carried out in mini-pigs and rats receiving unchanging doses of radionuclides with the food. The following findings were revealed for the elements examined: Fe, Se, Cs and Zn were characterized by very high transfer levels in the mother, infant and foetus. A substantial uptake by the mother alone was observed for Co, Ag and Mn. The uptake by the foetus and infant here was 1 to 10 times lower. A preferential concentration in certain tissues was seen for Sr and Tc; the thyroid levels of Tc were about equally high in mothers and infants, while Sr showed less accumulation in the maternal bone. The lanthanide group of substances (Ce, Eu and Gd as well as Y and Ru) were only taken up to a very limited extent. The uptake of the examined radionuclides (Fe, Co, Ag, Ce) with the food ingested was found here to be ten times greater in rats as compared to mini-pigs. This showed that great caution must be observed, if the behaviour of radionuclides in man is extrapolated from relevant data obtained in rodents. (orig./MG) [de

  16. Medical physics 2013. Abstracts

    International Nuclear Information System (INIS)

    Treuer, Harald

    2013-01-01

    The proceedings of the medical physics conference 2013 include abstract of lectures and poster sessions concerning the following issues: Tele-therapy - application systems, nuclear medicine and molecular imaging, neuromodulation, hearing and technical support, basic dosimetry, NMR imaging -CEST (chemical exchange saturation transfer), medical robotics, magnetic particle imaging, audiology, radiation protection, phase contrast - innovative concepts, particle therapy, brachytherapy, computerized tomography, quantity assurance, hybrid imaging techniques, diffusion and lung NMR imaging, image processing - visualization, cardiac and abdominal NMR imaging.

  17. Medical physics 2013. Abstracts; Medizinische Physik 2013. Abstractband

    Energy Technology Data Exchange (ETDEWEB)

    Treuer, Harald (ed.) [Koeln Univ. (Germany). Klinik fuer Stereotaxie und Funktionelle Neurochirurgie

    2013-07-01

    The proceedings of the medical physics conference 2013 include abstract of lectures and poster sessions concerning the following issues: Tele-therapy - application systems, nuclear medicine and molecular imaging, neuromodulation, hearing and technical support, basic dosimetry, NMR imaging -CEST (chemical exchange saturation transfer), medical robotics, magnetic particle imaging, audiology, radiation protection, phase contrast - innovative concepts, particle therapy, brachytherapy, computerized tomography, quantity assurance, hybrid imaging techniques, diffusion and lung NMR imaging, image processing - visualization, cardiac and abdominal NMR imaging.

  18. Ethylene glycol modified 2-(2′-aminophenyl)benzothiazoles at the amino site: the excited-state N-H proton transfer reactions in aqueous solution, micelles and potential application in live-cell imaging

    International Nuclear Information System (INIS)

    Liu, Bo-Qing; Tsai, Yi-Hsuan; Li, Yi-Jhen; Chao, Chi-Min; Liu, Kuan-Miao; Chen, Yi-Ting; Chen, Yu-Wei; Chung, Kun-You; Tseng, Huan-Wei; Chou, Pi-Tai

    2016-01-01

    Triethylene glycol monomethyl ether and poly(ethylene glycol) monomethyl ether modified 2-(2′-aminophenyl)benzothiazoles, namely ABT-P3EG, ABT-P7EG and ABT-P12EG varied by different chain length of poly(ethylene glycol) at the amino site, were synthesized to probe their photophysical and bio-imaging properties. In polar, aprotic solvents such as CH 2 Cl 2 ultrafast excited-state intramolecular proton transfer (ESIPT) takes place, resulting in a large Stokes shifted tautomer emission in the green-yellow (550 nm) region. In neutral water, ABT-P12EG forms micelles with diameters of 15  ±  3 nm under a critical micelle concentration (CMC) of ∼80 μM, in which the tautomer emission is greatly enhanced free from water perturbation. Cytotoxicity experiments showed that all ABT-PnEGs have negligible cytotoxicity against HeLa cells even at doses as high as 1 mM. Live-cell imaging experiments were also performed, the results indicate that all ABT-PnEGs are able to enter HeLa cells. While the two-photon excitation emission of ABT-P3EG in cells cytoplasm shows concentration independence and is dominated by the anion blue fluorescence, ABT-P7EG and ABT-P12EG exhibit prominent green tautomer emission at  >  CMC and in part penetrate to the nuclei, adding an additional advantage for the cell imaging. (paper)

  19. Pigment organization effects on energy transfer and Chl a emission imaged in the diatoms C. meneghiniana and P. tricornutum in vivo: a confocal laser scanning fluorescence (CLSF) microscopy and spectroscopy study.

    Science.gov (United States)

    Premvardhan, Lavanya; Réfrégiers, Matthieu; Büchel, Claudia

    2013-09-26

    The (auto)fluorescence from three diatom strains, Cyclotella meneghiniana (Cm), Phaeodactylum tricornutum 1a (Pt1a), and Phaeodactylum UTex (PtUTex), has been imaged in vivo to submicrometer resolution using confocal laser scanning fluorescence (CLSF) microscopy. The diatoms are excited at 473 and 532 nm, energy primarily absorbed by the carotenoid fucoxanthin (Fx) found within the fucoxanthin chlorophyll a/c proteins (FCPs). On the basis of the fluorescence spectra measured in each image voxel, we obtain information about the spatial and energetic distribution of the terminal Chl a emitters, localized in the FCPs and the reaction centers of the PSII protein complexes, and the nature and location of the primary absorbers that are linked to these emitters; 532 nm excites the highly efficient Fx(red) light harvesters, and lesser amounts of Fx(green)s, that are enriched in some FCPs and preferentially transfer energy to PSII, compared to 473 nm, which excites almost equal amounts of all three previously identified sets of Fx--Fx(red), Fx(green) and Fx(blue)--as well as Chl c. The heterogeneous Chl a emission observed from the (C)LSF images indicates that the different Fx's serve different final emitters in P. tricornutum and suggest, at least in C. meneghiniana , a localization of FCPs with relatively greater Fx(red) content at the chloroplast edges, but with overall higher FCP concentration in the interior of the plastid. To better understand our results, the concentration-dependent ensemble-averaged diatom solution spectra are compared to the (auto)fluorescence spectra of individual diatoms, which indicate that pigment packing effects at an intracellular level do affect the diatoms' spectral properties, in particular, concerning a 710 nm emission band apparent under stress conditions. A species-specific response of the spectral signature to the incident light is also discussed in terms of the presence of a silica shell in Cm but not in Pt1a nor PtUTex.

  20. Gene transfer in rodents and primates as a new tool for modeling diseases in animals and assessing functions by in vivo imaging

    Energy Technology Data Exchange (ETDEWEB)

    Deglon, N. [Atomic Energy Commission (CEA), Dept. of Medical Research and MIRCen Program, 91 - Orsay (France)

    2006-07-01

    The identification of disease-causing genes in familial forms of neuro-degenerative disorders and the development of genetic models closely replicating human CNS pathologies have drastically changed our understanding of the molecular events leading to neuronal cell death. If these achievements open new opportunities of therapeutic interventions efficient delivery systems taking into account the specificity of the central nervous system are required to administer therapeutic candidates. In addition, there is a need to develop 1) genetic models in large animals that replicate late stages of the diseases and 2) imaging techniques suitable for longitudinal, quantitative and non-invasive evaluation of disease progression and the evaluation of new therapeutic strategies. Over the last few years, we have investigated the potential of lentiviral vectors as tool to model and treat CNS disorders. The use of lentiviral vectors to create animal model of these pathologies holds various advantages compared to classical transgenic approaches. Viral vectors are versatile, highly flexible tools to perform in vivo studies. Multiple genetic models can be created in a short period of time. High transduction efficiencies as well as robust and sustained trans-gene expression lead to the rapid appearance of functional and behavioral abnormalities and severe neuro-degeneration. Targeted injections in different brain areas can be used to investigate the regional specificity of the neuro-pathology and eliminate potential side effects associated with a widespread over-expression of the trans-gene. Finally, models can be established in different mammalian species including non-human primates, thereby providing an opportunity to assess complex behavioral changes and perform longitudinal follow-up of neuro-pathological alterations by imaging. We have demonstrated the proof of principle of this approach for Huntington's disease. We have shown that the intratriatal injection of lentiviral

  1. Gene transfer in rodents and primates as a new tool for modeling diseases in animals and assessing functions by in vivo imaging

    International Nuclear Information System (INIS)

    Deglon, N.

    2006-01-01

    The identification of disease-causing genes in familial forms of neuro-degenerative disorders and the development of genetic models closely replicating human CNS pathologies have drastically changed our understanding of the molecular events leading to neuronal cell death. If these achievements open new opportunities of therapeutic interventions efficient delivery systems taking into account the specificity of the central nervous system are required to administer therapeutic candidates. In addition, there is a need to develop 1) genetic models in large animals that replicate late stages of the diseases and 2) imaging techniques suitable for longitudinal, quantitative and non-invasive evaluation of disease progression and the evaluation of new therapeutic strategies. Over the last few years, we have investigated the potential of lentiviral vectors as tool to model and treat CNS disorders. The use of lentiviral vectors to create animal model of these pathologies holds various advantages compared to classical transgenic approaches. Viral vectors are versatile, highly flexible tools to perform in vivo studies. Multiple genetic models can be created in a short period of time. High transduction efficiencies as well as robust and sustained trans-gene expression lead to the rapid appearance of functional and behavioral abnormalities and severe neuro-degeneration. Targeted injections in different brain areas can be used to investigate the regional specificity of the neuro-pathology and eliminate potential side effects associated with a widespread over-expression of the trans-gene. Finally, models can be established in different mammalian species including non-human primates, thereby providing an opportunity to assess complex behavioral changes and perform longitudinal follow-up of neuro-pathological alterations by imaging. We have demonstrated the proof of principle of this approach for Huntington's disease. We have shown that the intratriatal injection of lentiviral vector

  2. Facilitating Transfers

    DEFF Research Database (Denmark)

    Kjær, Poul F.

    2018-01-01

    Departing from the paradox that globalisation has implied an increase, rather than a decrease, in contextual diversity, this paper re-assesses the function, normative purpose and location of Regulatory Governance Frameworks in world society. Drawing on insights from sociology of law and world...... society studies, the argument advanced is that Regulatory Governance Frameworks are oriented towards facilitating transfers of condensed social components, such as economic capital and products, legal acts, political decisions and scientific knowledge, from one legally-constituted normative order, i.......e. contextual setting, to another. Against this background, it is suggested that Regulatory Governance Frameworks can be understood as schemes which act as ‘rites of passage’ aimed at providing legal stabilisation to social processes characterised by liminality, i.e ambiguity, hybridity and in-betweenness....

  3. Skeletal Muscle Magnetic Resonance Imaging of the Lower Limbs in Late-onset Lipid Storage Myopathy with Electron Transfer Flavoprotein Dehydrogenase Gene Mutations

    Institute of Scientific and Technical Information of China (English)

    Xin-Yi Liu; Ming Jin; Zhi-Qiang Wang; Dan-Ni Wang; Jun-Jie He; Min-Ting Lin; Hong-Xia Fu

    2016-01-01

    Background:Lipid storage myopathy (LSM) is a genetically heterogeneous group with variable clinical phenotypes.Late-onset multiple acyl-coenzyme A dehydrogenation deficiency (MADD) is a rather common form of LSM in China.Diagnosis and clinical management of it remain challenging,especially without robust muscle biopsy result and genetic detection.As the noninvasion and convenience,muscle magnetic resonance imaging (MRI) is a helpful assistant,diagnostic tool for neuromuscular disorders.However,the disease-specific MRI patterns of muscle involved and its diagnostic value in late-onset MADD have not been systematic analyzed.Methods:We assessed the MRI pattern and fat infiltration degree of the lower limb muscles in 28 late-onset MADD patients,combined with detailed clinical features and gene spectrum.Fat infiltration degree of the thigh muscle was scored while that ofgluteus was described as obvious or not.Associated muscular atrophy was defined as obvious muscle bulk reduction.Results:The mean scores were significantly different among the anterior,medial,and posterior thigh muscle groups.The mean of fat infiltration scores on posterior thigh muscle group was significantly higher than either anterior or medial thigh muscle group (P < 0.001).Moreover,the mean score on medial thigh muscle group was significantly higher than that of anterior thigh muscle group (P < 0.01).About half of the patients displayed fat infiltration and atrophy in gluteus muscles.Of 28 patients,12 exhibited atrophy in medial and/or posterior thigh muscle groups,especially in posterior thigh muscle group.Muscle edema pattern was not found in all the patients.Conclusions:Late-onset MADD patients show a typical muscular imaging pattern of fat infiltration and atrophy on anterior,posterior,and medial thigh muscle groups,with major involvement of posterior thigh muscle group and gluteus muscles and a sparing involvement of anterior thigh compartment.Our findings also suggest that muscle MRI of

  4. Light scattering reviews 8 radiative transfer and light scattering

    CERN Document Server

    Kokhanovsky, Alexander A

    2013-01-01

    Light scattering review (vol 8) is aimed at the presentation of recent advances in radiative transfer and light scattering optics. The topics to be covered include: scattering of light by irregularly shaped particles suspended in atmosphere (dust, ice crystals), light scattering by particles much larger as compared the wavelength of incident radiation, atmospheric radiative forcing, astrophysical radiative transfer, radiative transfer and optical imaging in biological media, radiative transfer of polarized light, numerical aspects of radiative transfer.

  5. Image, Image, Image

    Science.gov (United States)

    Howell, Robert T.

    2004-01-01

    With all the talk today about accountability, budget cuts, and the closing of programs in public education, teachers cannot overlook the importance of image in the field of industrial technology. It is very easy for administrators to cut ITE (industrial technology education) programs to save school money--money they might shift to teaching the…

  6. Radiopharmaceuticals to monitor gene transfer

    International Nuclear Information System (INIS)

    Wiebe, L. I.; Morin, K. W.; Knaus, E. E.

    1997-01-01

    Advances in genetic engineering and molecular biology have opened the door to disease treatment by transferring genes to cells that are responsible for the pathological condition being addressed. These genes can serve to supplement or introduce the function of indigenous genes that are either inadequately expressed or that are congenitally absent in the patient. They can introduce new functions such as drug sensitization to provide a unique therapeutic target. Gene transfer is readily monitored in vitro using a range of histochemical and biochemical tests that are ''built in'' to the therapeutic gene cassette. In vivo, in situ monitoring of the gene transfer and gene expression processes can be achieved with these tests only if biopsy is possible. Scintigraphic imaging can offer unique information on both the extent and location of gene expression, provided that an appropriate reporter gene is included in the therapeutic cassette. This overview includes a brief orientation to gene transfer therapy and is followed by a review of current approaches to gene therapy imaging. The concluding section deals with imaging based on radiolabelled nucleoside substrates for herpes simplex type-1 thymidine kinase, with emphasis on IVFRU, a stable potent and selective HSV-1 TK substrate developed in their laboratories

  7. Heat transfer: Pittsburgh 1987

    International Nuclear Information System (INIS)

    Lyczkowski, R.W.

    1987-01-01

    This book contains papers divided among the following sections: Process Heat Transfer; Thermal Hydraulics and Phase Change Phenomena; Analysis of Multicomponent Multiphase Flow and Heat Transfer; Heat Transfer in Advanced Reactors; General Heat Transfer in Solar Energy; Numerical Simulation of Multiphase Flow and Heat Transfer; High Temperature Heat Transfer; Heat Transfer Aspects of Severe Reactor Accidents; Hazardous Waste On-Site Disposal; and General Papers

  8. Transfer and Social Practice.

    Science.gov (United States)

    Billett, Stephen

    1998-01-01

    Transfer involves disembodying knowledge and transferring it for use in different contexts. Vocational knowledge arises in communities of practice, and difficulties arise in transferring it from one distinct community, such as a workplace, to another, such as a classroom. (SK)

  9. International technology transfer

    International Nuclear Information System (INIS)

    Kwon, Won Gi

    1991-11-01

    This book introduces technology progress and economic growth, theoretical consideration of technology transfer, policy and mechanism on technology transfer of a developed country and a developing country, reality of international technology transfer technology transfer and industrial structure in Asia and the pacific region, technology transfer in Russia, China and Eastern Europe, cooperation of science and technology for development of Northeast Asia and strategy of technology transfer of Korea.

  10. Technology transfer by multinationals

    OpenAIRE

    Kostyantyn Zuzik

    2003-01-01

    The paper analyses the issue of technology transfer by multinational corporations. The following questions are explored: (a) world market of technologies, the role of MNCs (b) Choice of the technology transfer mode, Dunning's OLI-theory as a factor of the choice of the mode of transfer (c) measurement and profitability of technology transfer (d) transfer of technology through partnerships, JVs, alliances and through M&As (e) aspects of technology transfer by services multinationals. Paper uti...

  11. Measurement of creatine kinase reaction rate in human brain using magnetization transfer image-selected in vivo spectroscopy (MT-ISIS) and a volume ³¹P/¹H radiofrequency coil in a clinical 3-T MRI system.

    Science.gov (United States)

    Jeong, Eun-Kee; Sung, Young-Hoon; Kim, Seong-Eun; Zuo, Chun; Shi, Xianfeng; Mellon, Eric A; Renshaw, Perry F

    2011-08-01

    High-energy phosphate metabolism, which allows the synthesis and regeneration of adenosine triphosphate (ATP), is a vital process for neuronal survival and activity. In particular, creatine kinase (CK) serves as an energy reservoir for the rapid buffering of ATP levels. Altered CK enzyme activity, reflecting compromised high-energy phosphate metabolism or mitochondrial dysfunction in the brain, can be assessed using magnetization transfer (MT) MRS. MT (31)P MRS has been used to measure the forward CK reaction rate in animal and human brain, employing a surface radiofrequency coil. However, long acquisition times and excessive radiofrequency irradiation prevent these methods from being used routinely for clinical evaluations. In this article, a new MT (31)P MRS method is presented, which can be practically used to measure the CK forward reaction rate constant in a clinical MRI system employing a volume head (31)P coil for spatial localization, without contamination from the scalp muscle, and an acquisition time of 30 min. Other advantages associated with the method include radiofrequency homogeneity within the regions of interest of the brain using a volume coil with image-selected in vivo spectroscopy localization, and reduction of the specific absorption rate using nonadiabatic radiofrequency pulses for MT saturation. The mean value of k(f) was measured as 0.320 ± 0.075 s(-1) from 10 healthy volunteers with an age range of 18-40 years. These values are consistent with those obtained using earlier methods, and the technique may be used routinely to evaluate energetic processes in the brain on a clinical MRI system. Copyright © 2010 John Wiley & Sons, Ltd.

  12. Cryogenic heat transfer

    CERN Document Server

    Barron, Randall F

    2016-01-01

    Cryogenic Heat Transfer, Second Edition continues to address specific heat transfer problems that occur in the cryogenic temperature range where there are distinct differences from conventional heat transfer problems. This updated version examines the use of computer-aided design in cryogenic engineering and emphasizes commonly used computer programs to address modern cryogenic heat transfer problems. It introduces additional topics in cryogenic heat transfer that include latent heat expressions; lumped-capacity transient heat transfer; thermal stresses; Laplace transform solutions; oscillating flow heat transfer, and computer-aided heat exchanger design. It also includes new examples and homework problems throughout the book, and provides ample references for further study.

  13. La méthodologie de l’image peut-elle être utile à la recherche en sciences sociales?

    OpenAIRE

    Haicault, Monique

    2011-01-01

    Si l'image n'a pas encore toute la place qui devrait lui revenir dans le champ des méthodologies en Sciences Sociales, c'est d'abord parce que son langage utilise un système de signes qui lui est spécifique, distinct de l'oral et de l'écrit. La méthodologie de l'image doit forger ses propres règles de collecte de données audiovisuelles, ses codes d'analyse et d'interprétation, afin de donner un sens sociologique à la " banalité " de ce qui est observé et enregistré. Elle doit aussi se plier a...

  14. Analysis of Heat Transfer

    International Nuclear Information System (INIS)

    2003-08-01

    This book deals with analysis of heat transfer which includes nonlinear analysis examples, radiation heat transfer, analysis of heat transfer in ANSYS, verification of analysis result, analysis of heat transfer of transition with automatic time stepping and open control, analysis of heat transfer using arrangement of ANSYS, resistance of thermal contact, coupled field analysis such as of thermal-structural interaction, cases of coupled field analysis, and phase change.

  15. Continuous imaging space in three-dimensional integral imaging

    International Nuclear Information System (INIS)

    Zhang Lei; Yang Yong; Wang Jin-Gang; Zhao Xing; Fang Zhi-Liang; Yuan Xiao-Cong

    2013-01-01

    We report an integral imaging method with continuous imaging space. This method simultaneously reconstructs real and virtual images in the virtual mode, with a minimum gap that separates the entire imaging space into real and virtual space. Experimental results show that the gap is reduced to 45% of that in a conventional integral imaging system with the same parameters. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  16. Expert Performance Transfer: Making Knowledge Transfer Count

    International Nuclear Information System (INIS)

    Turner, C.L.; Braudt, T.E.

    2011-01-01

    'Knowledge Transfer' is a high-priority imperative as the nuclear industry faces the combined effects of an aging workforce and economic pressures to do more with less. Knowledge Transfer is only a part of the solution to these challenges, however. The more compelling and immediate need faced by industry is Accomplishment Transfer, or the transference of the applied knowledge necessary to assure optimal performance transfer from experienced, high-performing staff to inexperienced staff. A great deal of industry knowledge and required performance information has been documented in the form of procedures. Often under-appreciated either as knowledge stores or as drivers of human performance, procedures, coupled with tightly-focused and effective training, are arguably the most effective influences on human and plant performance. (author)

  17. Waste Transfer Stations

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund

    2011-01-01

    tion and transport is usually the most costly part of any waste management system; and when waste is transported over a considerable distance or for a long time, transferring the waste from the collection vehicles to more efficient transportation may be economically beneficial. This involves...... a transfer station where the transfer takes place. These stations may also be accessible by private people, offering flexibility to the waste system, including facilities for bulky waste, household hazardous waste and recyclables. Waste transfer may also take place on the collection route from small...... describes the main features of waste transfer stations, including some considerations about the economical aspects on when transfer is advisable....

  18. Sketch Style Recognition, Transfer and Synthesis of Hand-Drawn Sketches

    KAUST Repository

    Shaheen, Sara

    2017-01-01

    exploits techniques from multi-disciplinary areas including geometrical modeling and image processing. It consists of two methods of transfer: stroke-style and brush-style transfer. (1) Stroke-style transfer aims to transfer the style of the input sketch

  19. Convective heat transfer

    CERN Document Server

    Kakac, Sadik; Pramuanjaroenkij, Anchasa

    2014-01-01

    Intended for readers who have taken a basic heat transfer course and have a basic knowledge of thermodynamics, heat transfer, fluid mechanics, and differential equations, Convective Heat Transfer, Third Edition provides an overview of phenomenological convective heat transfer. This book combines applications of engineering with the basic concepts of convection. It offers a clear and balanced presentation of essential topics using both traditional and numerical methods. The text addresses emerging science and technology matters, and highlights biomedical applications and energy technologies. What’s New in the Third Edition: Includes updated chapters and two new chapters on heat transfer in microchannels and heat transfer with nanofluids Expands problem sets and introduces new correlations and solved examples Provides more coverage of numerical/computer methods The third edition details the new research areas of heat transfer in microchannels and the enhancement of convective heat transfer with nanofluids....

  20. Introduction to heat transfer

    CERN Document Server

    SUNDÉN, B

    2012-01-01

    Presenting the basic mechanisms for transfer of heat, Introduction to Heat Transfer gives a deeper and more comprehensive view than existing titles on the subject. Derivation and presentation of analytical and empirical methods are provided for calculation of heat transfer rates and temperature fields as well as pressure drop. The book covers thermal conduction, forced and natural laminar and turbulent convective heat transfer, thermal radiation including participating media, condensation, evaporation and heat exchangers.

  1. Intramolecular Energy Transfer, Charge Transfer & Hydrogen Bond

    Indian Academy of Sciences (India)

    Ultrafast Dynamics of Chemical Reactions in Condensed Phase: Intramolecular Energy Transfer, Charge Transfer & Hydrogen Bond · PowerPoint Presentation · Slide 3 · Slide 4 · Slide 5 · Slide 6 · Slide 7 · Slide 8 · Slide 9 · Slide 10 · Slide 11 · Slide 12 · Slide 13 · Slide 14 · Slide 15 · Slide 16 · Slide 17 · Slide 18 · Slide 19.

  2. Heat transfer system

    Science.gov (United States)

    Not Available

    1980-03-07

    A heat transfer system for a nuclear reactor is described. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

  3. Fuel transfer machine

    International Nuclear Information System (INIS)

    Bernstein, I.

    1978-01-01

    A nuclear fuel transfer machine for transferring fuel assemblies through the fuel transfer tube of a nuclear power generating plant containment structure is described. A conventional reversible drive cable is attached to the fuel transfer carriage to drive it horizontally through the tube. A shuttle carrying a sheave at each end is arranged in parallel with the carriage to also travel into the tube. The cable cooperating with the sheaves permit driving a relatively short fuel transfer carriage a large distance without manually installing sheaves or drive apparatus in the tunnel. 8 claims, 3 figures

  4. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  5. Using transfer learning to detect galaxy mergers

    Science.gov (United States)

    Ackermann, Sandro; Schawinksi, Kevin; Zhang, Ce; Weigel, Anna K.; Turp, M. Dennis

    2018-05-01

    We investigate the use of deep convolutional neural networks (deep CNNs) for automatic visual detection of galaxy mergers. Moreover, we investigate the use of transfer learning in conjunction with CNNs, by retraining networks first trained on pictures of everyday objects. We test the hypothesis that transfer learning is useful for improving classification performance for small training sets. This would make transfer learning useful for finding rare objects in astronomical imaging datasets. We find that these deep learning methods perform significantly better than current state-of-the-art merger detection methods based on nonparametric systems like CAS and GM20. Our method is end-to-end and robust to image noise and distortions; it can be applied directly without image preprocessing. We also find that transfer learning can act as a regulariser in some cases, leading to better overall classification accuracy (p = 0.02). Transfer learning on our full training set leads to a lowered error rate from 0.0381 down to 0.0321, a relative improvement of 15%. Finally, we perform a basic sanity-check by creating a merger sample with our method, and comparing with an already existing, manually created merger catalogue in terms of colour-mass distribution and stellar mass function.

  6. Transfer function combinations

    KAUST Repository

    Zhou, Liang; Schott, Mathias; Hansen, Charles

    2012-01-01

    Direct volume rendering has been an active area of research for over two decades. Transfer function design remains a difficult task since current methods, such as traditional 1D and 2D transfer functions, are not always effective for all data sets. Various 1D or 2D transfer function spaces have been proposed to improve classification exploiting different aspects, such as using the gradient magnitude for boundary location and statistical, occlusion, or size metrics. In this paper, we present a novel transfer function method which can provide more specificity for data classification by combining different transfer function spaces. In this work, a 2D transfer function can be combined with 1D transfer functions which improve the classification. Specifically, we use the traditional 2D scalar/gradient magnitude, 2D statistical, and 2D occlusion spectrum transfer functions and combine these with occlusion and/or size-based transfer functions to provide better specificity. We demonstrate the usefulness of the new method by comparing to the following previous techniques: 2D gradient magnitude, 2D occlusion spectrum, 2D statistical transfer functions and 2D size based transfer functions. © 2012 Elsevier Ltd.

  7. Heat transfer enhancement

    International Nuclear Information System (INIS)

    Hasatani, Masanobu; Itaya, Yoshinori

    1985-01-01

    In order to develop energy-saving techniques and new energy techniques, and also most advanced techniques by making industrial equipment with high performance, heat transfer performance frequently becomes an important problem. In addition, the improvement of conventional heat transfer techniques and the device of new heat transfer techniques are often required. It is most proper that chemical engineers engage in the research and development for enhancing heat transfer. The research and development for enhancing heat transfer are important to heighten heat exchange efficiency or to cool equipment for preventing overheat in high temperature heat transfer system. In this paper, the techniques of enhancing radiative heat transfer and the improvement of radiative heat transfer characteristics are reported. Radiative heat transfer is proportional to fourth power of absolute temperature, and it does not require any heat transfer medium, but efficient heat-radiation converters are necessary. As the techniques of enhancing radiative heat transfer, the increase of emission and absorption areas, the installation of emissive structures and the improvement of radiative characteristics are discussed. (Kako, I.)

  8. Transfer function combinations

    KAUST Repository

    Zhou, Liang

    2012-10-01

    Direct volume rendering has been an active area of research for over two decades. Transfer function design remains a difficult task since current methods, such as traditional 1D and 2D transfer functions, are not always effective for all data sets. Various 1D or 2D transfer function spaces have been proposed to improve classification exploiting different aspects, such as using the gradient magnitude for boundary location and statistical, occlusion, or size metrics. In this paper, we present a novel transfer function method which can provide more specificity for data classification by combining different transfer function spaces. In this work, a 2D transfer function can be combined with 1D transfer functions which improve the classification. Specifically, we use the traditional 2D scalar/gradient magnitude, 2D statistical, and 2D occlusion spectrum transfer functions and combine these with occlusion and/or size-based transfer functions to provide better specificity. We demonstrate the usefulness of the new method by comparing to the following previous techniques: 2D gradient magnitude, 2D occlusion spectrum, 2D statistical transfer functions and 2D size based transfer functions. © 2012 Elsevier Ltd.

  9. Making benefit transfers work

    DEFF Research Database (Denmark)

    Bateman, I.J.; Brouwer, R.; Ferrini, S.

    We develop and test guidance principles for benefits transfers. These argue that when transferring across relatively similar sites, simple mean value transfers are to be preferred but that when sites are relatively dissimilar then value function transfers will yield lower errors. The paper also...... provides guidance on the appropriate specification of transferable value functions arguing that these should be developed from theoretical rather than ad-hoc statistical principles. These principles are tested via a common format valuation study of water quality improvements across five countries. Results...... support our various hypotheses providing a set of principles for future transfer studies. The application also considers new ways of incorporating distance decay, substitution and framing effects within transfers and presents a novel water quality ladder....

  10. Image processing of integrated video image obtained with a charged-particle imaging video monitor system

    International Nuclear Information System (INIS)

    Iida, Takao; Nakajima, Takehiro

    1988-01-01

    A new type of charged-particle imaging video monitor system was constructed for video imaging of the distributions of alpha-emitting and low-energy beta-emitting nuclides. The system can display not only the scintillation image due to radiation on the video monitor but also the integrated video image becoming gradually clearer on another video monitor. The distortion of the image is about 5% and the spatial resolution is about 2 line pairs (lp)mm -1 . The integrated image is transferred to a personal computer and image processing is performed qualitatively and quantitatively. (author)

  11. Transfer Mispricing as an Argument for Corporate Social Responsibility

    OpenAIRE

    Asongu, Simplice; Nwachukwu, Jacinta C.

    2016-01-01

    This article presents a case for transfer mispricing as an argument for Corporate Social Responsibility (CSR). The argument builds on the position that in order to compensate for potential loss of brand image and reputation, Multinational Companies (MNCs) would be more socially responsible when they are operating in countries where the legislation and laws in place are not effective at identifying and sanctioning transfer mispricing. We first discuss the dark side of transfer pricing (TP), ne...

  12. Wireless adiabatic power transfer

    International Nuclear Information System (INIS)

    Rangelov, A.A.; Suchowski, H.; Silberberg, Y.; Vitanov, N.V.

    2011-01-01

    Research highlights: → Efficient and robust mid-range wireless energy transfer between two coils. → The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. → Wireless energy transfer is insensitive to any resonant constraints. → Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.

  13. Radioecology. Transfers of radioelements

    International Nuclear Information System (INIS)

    Foulquier, L.

    2002-01-01

    The study of the cycle of radioelements in the environment requires the measurement of the radionuclides present in all parts of the ecosystems. The knowledge of the mechanisms of radioactive pollutant transfers and of the kinetics of the exchanges between a source term, the vectors and the constituents of the biosphere represents heart of the work of radio-ecologists. This article describes briefly the techniques used for the measurement of radionuclides in the environment and for the study of their physical dispersion mechanisms. Then, it treats more carefully of the transfer mechanisms in different environments: 1 - tools for the evaluation of transfers: metrology, atmospheric and liquid dispersion phenomena; 2 - processes of radioelement transfers: transfers in aquatic ecosystems, transfers in terrestrial environment. (J.S.)

  14. Gas transfer system

    International Nuclear Information System (INIS)

    Oberlin, J.C.; Frick, G.; Kempfer, C.; North, C.

    1988-09-01

    The state of work on the Vivitron gas transfer system and the system functions are summarized. The system has to: evacuate the Vivitron reservoir; transfer gas from storage tanks to the Vivitron; recirculate gas during operation; transfer gas from the Vivitron to storage tanks; and assure air input. The system is now being installed. Leak alarms are given by SF6 detectors, which set off a system of forced ventilation. Another system continuously monitors the amount of SF6 in the tanks [fr

  15. Transfer vibration through spine

    OpenAIRE

    Benyovszky, Adam

    2012-01-01

    Transfer Vibration through Spine Abstract In the bachelor project we deal with the topic of Transfer Vibration through Spine. The problem of TVS is trying to be solved by the critical review method. We analyse some diagnostic methods and methods of treatment based on this principle. Close attention is paid to the method of Transfer Vibration through Spine that is being currently solved by The Research Institute of Thermomechanics in The Czech Academy of Sciences in cooperation with Faculty of...

  16. Nonparametric Transfer Function Models

    Science.gov (United States)

    Liu, Jun M.; Chen, Rong; Yao, Qiwei

    2009-01-01

    In this paper a class of nonparametric transfer function models is proposed to model nonlinear relationships between ‘input’ and ‘output’ time series. The transfer function is smooth with unknown functional forms, and the noise is assumed to be a stationary autoregressive-moving average (ARMA) process. The nonparametric transfer function is estimated jointly with the ARMA parameters. By modeling the correlation in the noise, the transfer function can be estimated more efficiently. The parsimonious ARMA structure improves the estimation efficiency in finite samples. The asymptotic properties of the estimators are investigated. The finite-sample properties are illustrated through simulations and one empirical example. PMID:20628584

  17. Basic heat transfer

    CERN Document Server

    Bacon, D H

    2013-01-01

    Basic Heat Transfer aims to help readers use a computer to solve heat transfer problems and to promote greater understanding by changing data values and observing the effects, which are necessary in design and optimization calculations.The book is concerned with applications including insulation and heating in buildings and pipes, temperature distributions in solids for steady state and transient conditions, the determination of surface heat transfer coefficients for convection in various situations, radiation heat transfer in grey body problems, the use of finned surfaces, and simple heat exc

  18. Containment condensing heat transfer

    International Nuclear Information System (INIS)

    Gido, R.G.; Koestel, A.

    1983-01-01

    This report presents a mechanistic heat-transfer model that is valid for large scale containment heat sinks. The model development is based on the determination that the condensation is controlled by mass diffusion through the vapor-air boundary layer, and the application of the classic Reynolds' analogy to formulate expressions for the transfer of heat and mass based on hydrodynamic measurements of the momentum transfer. As a result, the analysis depends on the quantification of the shear stress (momentum transfer) at the interface between the condensate film and the vapor-air boundary layer. In addition, the currently used Tagami and Uchida test observations and their range of applicability are explained

  19. Quantitative luminescence imaging system

    Science.gov (United States)

    Erwin, David N.; Kiel, Johnathan L.; Batishko, Charles R.; Stahl, Kurt A.

    1990-01-01

    The QLIS images and quantifies low-level chemiluminescent reactions in an electromagnetic field. It is capable of real time nonperturbing measurement and simultaneous recording of many biochemical and chemical reactions such as luminescent immunoassays or enzyme assays. The system comprises image transfer optics, a low-light level digitizing camera with image intensifying microchannel plates, an image process or, and a control computer. The image transfer optics may be a fiber image guide with a bend, or a microscope, to take the light outside of the RF field. Output of the camera is transformed into a localized rate of cumulative digitalized data or enhanced video display or hard-copy images. The system may be used as a luminescent microdosimetry device for radiofrequency or microwave radiation, as a thermal dosimeter, or in the dosimetry of ultra-sound (sonoluminescence) or ionizing radiation. It provides a near-real-time system capable of measuring the extremely low light levels from luminescent reactions in electromagnetic fields in the areas of chemiluminescence assays and thermal microdosimetry, and is capable of near-real-time imaging of the sample to allow spatial distribution analysis of the reaction. It can be used to instrument three distinctly different irradiation configurations, comprising (1) RF waveguide irradiation of a small Petri-dish-shaped sample cell, (2) RF irradiation of samples in a microscope for the microscopie imaging and measurement, and (3) RF irradiation of small to human body-sized samples in an anechoic chamber.

  20. Technology Transfer and Technology Transfer Intermediaries

    Science.gov (United States)

    Bauer, Stephen M.; Flagg, Jennifer L.

    2010-01-01

    A standard and comprehensive model is needed to evaluate and compare technology transfer systems and the stakeholders within these systems. The principle systems considered include federal laboratories, U.S. universities, the rehabilitation engineering research centers (RERCs), and large small business innovation research programs. An earlier…

  1. Imaging system

    International Nuclear Information System (INIS)

    Rushbrooke, J.G.; Ansorge, R.E.

    1987-01-01

    A moving object such as a container on a conveyor belt is imaged by an optical system onto a charge coupled device array in which the lines of the array are arranged perpendicular to the direction of motion of the object. The speed of movement of the object is sensed to generate electrical signals which are processed to provide shift signals enabling the shifting of data row to row in the array in synchronism with the movement of the container. The electrical charge associated with a given point on the array is transferred from one line to the other until it appears at the last line of the array, from which it is read out in known manner in conjunction with all other electrical charges associated with the row of charge coupled devices in the last line of the array. Due to the integrating effect achieved, the aperture of the imaging system can be much smaller than otherwise would be required, and/or the level of light illumination can be reduced. The imaging system can be applied to X-ray inspection devices, aerial surveillance or scanning of moving documents in copying processes. (author)

  2. An Interdistrict Transfer Program

    Science.gov (United States)

    Gross, Norman

    1975-01-01

    This testimony, before the May 1974 public hearings of the New York City Commission on Human Rights by the Administrator, Urban-Suburban Transfer Program and Inter district Transfer Program, West Irondequoit School District, New York, reviews a program which began with 25 minority group youngsters from one racially-imbalanced Rochester school…

  3. Transfer involving deformed nuclei

    International Nuclear Information System (INIS)

    Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.

    1985-03-01

    Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs

  4. Sustainable technology transfer

    NARCIS (Netherlands)

    Punter, H.T.; Krikhaar, R.L.; Bril, R.J.

    2006-01-01

    In this position paper we address the issue of transferring a technology from research into an industrial organization by presenting a refined process for technology transfer. Based on over two decades of industrial experience, we identified the need for a dedicated technology engineering phase for

  5. Radiative heat transfer

    CERN Document Server

    Modest, Michael F

    2013-01-01

    The third edition of Radiative Heat Transfer describes the basic physics of radiation heat transfer. The book provides models, methodologies, and calculations essential in solving research problems in a variety of industries, including solar and nuclear energy, nanotechnology, biomedical, and environmental. Every chapter of Radiative Heat Transfer offers uncluttered nomenclature, numerous worked examples, and a large number of problems-many based on real world situations-making it ideal for classroom use as well as for self-study. The book's 24 chapters cover the four major areas in the field: surface properties; surface transport; properties of participating media; and transfer through participating media. Within each chapter, all analytical methods are developed in substantial detail, and a number of examples show how the developed relations may be applied to practical problems. It is an extensive solution manual for adopting instructors. Features: most complete text in the field of radiative heat transfer;...

  6. Technology Transfer Issues and a New Technology Transfer Model

    Science.gov (United States)

    Choi, Hee Jun

    2009-01-01

    The following are major issues that should be considered for efficient and effective technology transfer: conceptions of technology, technological activity and transfer, communication channels, factors affecting transfer, and models of transfer. In particular, a well-developed model of technology transfer could be used as a framework for…

  7. Heat transfer enhancement using 2MHz ultrasound.

    Science.gov (United States)

    Bulliard-Sauret, Odin; Ferrouillat, Sebastien; Vignal, Laure; Memponteil, Alain; Gondrexon, Nicolas

    2017-11-01

    The present work focuses on possible heat transfer enhancement from a heating plate towards tap water in forced convection by means of 2MHz ultrasound. The thermal approach allows to observe the increase of local convective heat transfer coefficients in the presence of ultrasound and to deduce a correlation between ultrasound power and Nusselt number. Heat transfer coefficient under ultrasound remains constant while heat transfer coefficient under silent conditions increases with Reynolds number from 900 up to 5000. Therefore, heat transfer enhancement factor ranges from 25% up to 90% for the same energy conditions (supplied ultrasonic power=110W and supplied thermal power=450W). In the same time cavitational activity due to 2MHz ultrasound emission was characterized from mechanical and chemical viewpoints without significant results. At least, Particle Image Velocimetry (PIV) measurements have been performed in order to investigate hydrodynamic modifications due to the presence of 2MHz ultrasound. It was therefore possible to propose a better understanding of heat transfer enhancement mechanism with high frequency ultrasound. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Knowledge transfer isn’t simply transfer

    DEFF Research Database (Denmark)

    Dao, Li; Napier, Nancy

    2012-01-01

    This paper examines micro dynamic aspects of knowledge sharing and learning in international joint venture settings. Learning of expatriate and local managers appears far more complex and mutually dependent than conventionally speculated in existing literature. The paper proposes that the effect ...... Danish and Vietnamese firms. The paper suggests that learning in IJVs, even in the context of one-way knowledge transfer from the foreign parent, should be managed in a mutual perspective and with thoughtful coordination of individual learning....... and outcome of knowledge transfer from joint venture parents and learning in IJVs are dependent on how individual managers (including both expatriate and local) learn, perceive their learning roles, and enact a learning agenda. Empirical evidence is drawn from two cases of international joint ventures between...

  9. Large momentum transfer phenomena

    International Nuclear Information System (INIS)

    Imachi, Masahiro; Otsuki, Shoichiro; Matsuoka, Takeo; Sawada, Shoji.

    1978-01-01

    The large momentum transfer phenomena in hadron reaction drastically differ from small momentum transfer phenomena, and are described in this paper. Brief review on the features of the large transverse momentum transfer reactions is described in relation with two-body reactions, single particle productions, particle ratios, two jet structure, two particle correlations, jet production cross section, and the component of momentum perpendicular to the plane defined by the incident protons and the triggered pions and transverse momentum relative to jet axis. In case of two-body process, the exponent N of the power law of the differential cross section is a value between 10 to 11.5 in the large momentum transfer region. The breaks of the exponential behaviors into the power ones are observed at the large momentum transfer region. The break would enable to estimate the order of a critical length. The large momentum transfer phenomena strongly suggest an important role of constituents of hadrons in the hard region. Hard rearrangement of constituents from different initial hadrons induces large momentum transfer reactions. Several rules to count constituents in the hard region have been proposed so far to explain the power behavior. Scale invariant quark interaction and hard reactions are explained, and a summary of the possible types of hard subprocess is presented. (Kato, T.)

  10. Technology transfer 1994

    Energy Technology Data Exchange (ETDEWEB)

    1994-01-01

    This document, Technology Transfer 94, is intended to communicate that there are many opportunities available to US industry and academic institutions to work with DOE and its laboratories and facilities in the vital activity of improving technology transfer to meet national needs. It has seven major sections: Introduction, Technology Transfer Activities, Access to Laboratories and Facilities, Laboratories and Facilities, DOE Office, Technologies, and an Index. Technology Transfer Activities highlights DOE`s recent developments in technology transfer and describes plans for the future. Access to Laboratories and Facilities describes the many avenues for cooperative interaction between DOE laboratories or facilities and industry, academia, and other government agencies. Laboratories and Facilities profiles the DOE laboratories and facilities involved in technology transfer and presents information on their missions, programs, expertise, facilities, and equipment, along with data on whom to contact for additional information on technology transfer. DOE Offices summarizes the major research and development programs within DOE. It also contains information on how to access DOE scientific and technical information. Technologies provides descriptions of some of the new technologies developed at DOE laboratories and facilities.

  11. Dexter energy transfer pathways.

    Science.gov (United States)

    Skourtis, Spiros S; Liu, Chaoren; Antoniou, Panayiotis; Virshup, Aaron M; Beratan, David N

    2016-07-19

    Energy transfer with an associated spin change of the donor and acceptor, Dexter energy transfer, is critically important in solar energy harvesting assemblies, damage protection schemes of photobiology, and organometallic opto-electronic materials. Dexter transfer between chemically linked donors and acceptors is bridge mediated, presenting an enticing analogy with bridge-mediated electron and hole transfer. However, Dexter coupling pathways must convey both an electron and a hole from donor to acceptor, and this adds considerable richness to the mediation process. We dissect the bridge-mediated Dexter coupling mechanisms and formulate a theory for triplet energy transfer coupling pathways. Virtual donor-acceptor charge-transfer exciton intermediates dominate at shorter distances or higher tunneling energy gaps, whereas virtual intermediates with an electron and a hole both on the bridge (virtual bridge excitons) dominate for longer distances or lower energy gaps. The effects of virtual bridge excitons were neglected in earlier treatments. The two-particle pathway framework developed here shows how Dexter energy-transfer rates depend on donor, bridge, and acceptor energetics, as well as on orbital symmetry and quantum interference among pathways.

  12. Fast multilevel radiative transfer

    Science.gov (United States)

    Paletou, Frédéric; Léger, Ludovick

    2007-01-01

    The vast majority of recent advances in the field of numerical radiative transfer relies on approximate operator methods better known in astrophysics as Accelerated Lambda-Iteration (ALI). A superior class of iterative schemes, in term of rates of convergence, such as Gauss-Seidel and Successive Overrelaxation methods were therefore quite naturally introduced in the field of radiative transfer by Trujillo Bueno & Fabiani Bendicho (1995); it was thoroughly described for the non-LTE two-level atom case. We describe hereafter in details how such methods can be generalized when dealing with non-LTE unpolarised radiation transfer with multilevel atomic models, in monodimensional geometry.

  13. A heat transfer textbook

    CERN Document Server

    Lienhard, John H

    2011-01-01

    This introduction to heat transfer offers advanced undergraduate and graduate engineering students a solid foundation in the subjects of conduction, convection, radiation, and phase-change, in addition to the related topic of mass transfer. A staple of engineering courses around the world for more than three decades, it has been revised and updated regularly by the authors, a pair of recognized experts in the field. The text addresses the implications, limitations, and meanings of many aspects of heat transfer, connecting the subject to its real-world applications and developing students' ins

  14. Excavating a transfer tunnel

    CERN Multimedia

    Laurent Guiraud

    2000-01-01

    The transfer tunnel being dug here will take the 450 GeV beam from the SPS and inject it into the LHC where the beam energies will be increased to 7 TeV. In order to transfer this beam from the SPS to the LHC, two transfer tunnels are used to circulate the beams in opposite directions. When excavated, the accelerator components, including magnets, beam pipes and cryogenics will be installed and connected to both the SPS and LHC ready for operation to begin in 2008.

  15. [Countertransference in homoerotic transference].

    Science.gov (United States)

    Junkert-Tress, B; Reister, G

    1995-01-01

    Until now psychoanalytic training and literature have hardly considered the transference love of homosexual patients. We summarized the scarce literature and related it to the background of our knowledge of heterosexual transference love. The discussion leaves no doubt that, like the heterosexual, homosexual transference love must be read on all levels of psychosexual development instead of reading it on only one and definitely not on an amorphous "preoedipal" level. This is particularly true for the level of the adult homosexual patient, as the case history demonstrates.

  16. Comparisons of power transfer functions and flow transfer functions

    International Nuclear Information System (INIS)

    Grimm, K.N.; Meneghetti, D.

    1987-01-01

    Transfer functions may be used to calculate component feedbacks or temperature increments by convolution of the transfer function with the appropriate fractional change in system-quantity. Power-change transfer functions have been reported. The corresponding flow transfer functions for this case, and comparison with the power transfer functions, are reported here. Results of feedback simulation of ramped flow transients using flow transfer functions are also described

  17. Liquefied Natural Gas Transfer

    Science.gov (United States)

    1980-01-01

    Chicago Bridge & Iron Company's tanks and associated piping are parts of system for transferring liquefied natural gas from ship to shore and storing it. LNG is a "cryogenic" fluid meaning that it must be contained and transferred at very low temperatures, about 260 degrees below Fahrenheit. Before the LNG can be pumped from the ship to the storage tanks, the two foot diameter transfer pipes must be cooled in order to avoid difficulties associated with sharp differences of temperature between the supercold fluid and relatively warm pipes. Cooldown is accomplished by sending small steady flow of the cryogenic substance through the pipeline; the rate of flow must be precisely controlled or the transfer line will be subjected to undesirable thermal stress.

  18. Electron transfer in proteins

    DEFF Research Database (Denmark)

    Farver, O; Pecht, I

    1991-01-01

    Electron migration between and within proteins is one of the most prevalent forms of biological energy conversion processes. Electron transfer reactions take place between active centers such as transition metal ions or organic cofactors over considerable distances at fast rates and with remarkable...... specificity. The electron transfer is attained through weak electronic interaction between the active sites, so that considerable research efforts are centered on resolving the factors that control the rates of long-distance electron transfer reactions in proteins. These factors include (in addition......-containing proteins. These proteins serve almost exclusively in electron transfer reactions, and as it turns out, their metal coordination sites are endowed with properties uniquely optimized for their function....

  19. Industrial technology transfer

    International Nuclear Information System (INIS)

    Bulger, W.

    1982-06-01

    The transfer of industrial technology is an essential part of the CANDU export marketing program. Potential customers require the opportunity to become self-sufficient in the supply of nuclear plant and equipment in the long term and they require local participation to the maximum extent possible. The Organization of CANDU Industries is working closely with Atomic Energy of Canada Ltd. in developing comprehensive programs for the transfer of manufacturing technology. The objectives of this program are: 1) to make available to the purchasing country all nuclear component manufacturing technology that exists in Canada; and 2) to assure that the transfer of technology takes place in an efficient and effective way. Technology transfer agreements may be in the form of joint ventures or license agreements, depending upon the requirements of the recipient

  20. Fast multilevel radiative transfer

    International Nuclear Information System (INIS)

    Paletou, Frederic; Leger, Ludovick

    2007-01-01

    The vast majority of recent advances in the field of numerical radiative transfer relies on approximate operator methods better known in astrophysics as Accelerated Lambda-Iteration (ALI). A superior class of iterative schemes, in term of rates of convergence, such as Gauss-Seidel and successive overrelaxation methods were therefore quite naturally introduced in the field of radiative transfer by Trujillo Bueno and Fabiani Bendicho [A novel iterative scheme for the very fast and accurate solution of non-LTE radiative transfer problems. Astrophys J 1995;455:646]; it was thoroughly described for the non-LTE two-level atom case. We describe hereafter in details how such methods can be generalized when dealing with non-LTE unpolarised radiation transfer with multilevel atomic models, in monodimensional geometry

  1. Technology transfer quality assurance

    International Nuclear Information System (INIS)

    Hood, F.C.

    1991-03-01

    The results of research conducted at Pacific Northwest Laboratory (PNL) for the DOE are regularly transferred from the laboratory to the private sector. The principal focus of PNL is on environmental research and waste management technology; other programs of emphasis include molecular science research. The technology transfer process is predicated on Quality to achieve its objectives effectively. Total quality management (TQM) concepts and principles readily apply to the development and translation of new scientific concepts into commercial products. The concept of technology transfer epitomizes the TQM tenet of continuous improvement: always striving for a better way to do things and always satisfying the customer. A successful technology transfer process adds value to society by providing new or enhanced processes, products, and services to government and commercial customers, with a guarantee of product pedigree and process validity. 2 refs

  2. Analytical heat transfer

    CERN Document Server

    Han, Je-Chin

    2012-01-01

    … it will complete my library … [and] complement the existing literature on heat transfer. It will be of value for both graduate students and faculty members.-Bengt Sunden, Lund University, Sweden

  3. Technology transfer for adaptation

    Science.gov (United States)

    Biagini, Bonizella; Kuhl, Laura; Gallagher, Kelly Sims; Ortiz, Claudia

    2014-09-01

    Technology alone will not be able to solve adaptation challenges, but it is likely to play an important role. As a result of the role of technology in adaptation and the importance of international collaboration for climate change, technology transfer for adaptation is a critical but understudied issue. Through an analysis of Global Environment Facility-managed adaptation projects, we find there is significantly more technology transfer occurring in adaptation projects than might be expected given the pessimistic rhetoric surrounding technology transfer for adaptation. Most projects focused on demonstration and early deployment/niche formation for existing technologies rather than earlier stages of innovation, which is understandable considering the pilot nature of the projects. Key challenges for the transfer process, including technology selection and appropriateness under climate change, markets and access to technology, and diffusion strategies are discussed in more detail.

  4. Controlled Environment Specimen Transfer

    DEFF Research Database (Denmark)

    Damsgaard, Christian Danvad; Zandbergen, Henny W.; Hansen, Thomas Willum

    2014-01-01

    an environmental transmission electron microscope to an in situ X-ray diffractometer through a dedicated transmission electron microscope specimen transfer holder, capable of sealing the specimen in a gaseous environment at elevated temperatures. Two catalyst material systems have been investigated; Cu/ZnO/Al2O3...... transferred in a reactive environment to the environmental transmission electron microscope where further analysis on the local scale were conducted. The Co/Al2O3 catalyst was reduced in the environmental microscope and successfully kept reduced outside the microscope in a reactive environment. The in situ......Specimen transfer under controlled environment conditions, such as temperature, pressure, and gas composition, is necessary to conduct successive complementary in situ characterization of materials sensitive to ambient conditions. The in situ transfer concept is introduced by linking...

  5. Pneumatic transfer systems

    International Nuclear Information System (INIS)

    Bichler, H.; Boeck, H.; Hammer, J.; Buchtela, K.

    1988-11-01

    A pneumatic transfer system for research reactors, including a sample changer system and to be used for neutron activation analysis, is described. The system can be obtained commercially from the Atominstitut. 2 figs. (qui)

  6. Theories Supporting Transfer of Training.

    Science.gov (United States)

    Yamnill, Siriporn; McLean, Gary N.

    2001-01-01

    Reviews theories about factors affecting the transfer of training, including theories on motivation (expectancy, equity, goal setting), training transfer design (identical elements, principle, near and far), and transfer climate (organizational). (Contains 36 references.) (SK)

  7. Convection heat transfer

    CERN Document Server

    Bejan, Adrian

    2013-01-01

    Written by an internationally recognized authority on heat transfer and thermodynamics, this second edition of Convection Heat Transfer contains new and updated problems and examples reflecting real-world research and applications, including heat exchanger design. Teaching not only structure but also technique, the book begins with the simplest problem solving method (scale analysis), and moves on to progressively more advanced and exact methods (integral method, self similarity, asymptotic behavior). A solutions manual is available for all problems and exercises.

  8. Credit risk transfer

    OpenAIRE

    Bank for International Settlements

    2003-01-01

    Executive summary Techniques for transferring credit risk, such as financial guarantees and credit insurance, have been a long-standing feature of financial markets. In the past few years, however, the range of credit risk transfer (CRT) instruments and the circumstances in which they are used have widened considerably. A number of factors have contributed to this growth, including: greater focus by banks and other financial institutions on risk management; a more rigorous approach to risk/re...

  9. Heat transfer II essentials

    CERN Document Server

    REA, The Editors of

    1988-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Heat Transfer II reviews correlations for forced convection, free convection, heat exchangers, radiation heat transfer, and boiling and condensation.

  10. Transfer og effekt

    DEFF Research Database (Denmark)

    Sørensen, Peter

    2017-01-01

    Effekt, virkning eller udbytte af en lederuddannelse afhænger af en række individuelle, uddannelsesmæssige og organisatoriske faktorer. Det ved vi fra uddannelsesforskningen og særligt fra forskningen i transfer. Kun hvis uddannelsesinstitutionerne såvel som de studerende og arbejdspladserne vil...... medvirke aktivt til at skabe og fremme transfer, kan man gøre sig forhåbninger om, at få effekt af en lederuddannelse....

  11. Advances in heat transfer

    CERN Document Server

    Hartnett, James P; Cho, Young I; Greene, George A

    2001-01-01

    Heat transfer is the exchange of heat energy between a system and its surrounding environment, which results from a temperature difference and takes place by means of a process of thermal conduction, mechanical convection, or electromagnetic radiation. Advances in Heat Transfer is designed to fill the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than is allowable in either journals or texts.

  12. Effective Bayesian Transfer Learning

    Science.gov (United States)

    2010-03-01

    the class of algorithms analyzed by Bartlett’s work under task R4). With emphasis on transferring one type of objects to another, (e.g., coffee cups...obstacles, so those are temporarily pruned from the graph. In addition, the start and goal locations may not be currently included in the graph. They carried...Transfer Level 3 Varying shape within class Task A: Instances of an object from the same class. ( Coffee mug) Task B: Instances of a different object

  13. Shielded cells transfer automation

    International Nuclear Information System (INIS)

    Fisher, J.J.

    1984-01-01

    Nuclear waste from shielded cells is removed, packaged, and transferred manually in many nuclear facilities. Radiation exposure is absorbed by operators during these operations and limited only through procedural controls. Technological advances in automation using robotics have allowed a production waste removal operation to be automated to reduce radiation exposure. The robotic system bags waste containers out of glove box and transfers them to a shielded container. Operators control the system outside the system work area via television cameras. 9 figures

  14. Multiple foci of splenic tissue autotransplantation: Splenosis in diagnostic imaging

    International Nuclear Information System (INIS)

    Laskowska, K.; Burzynska-Makuch, M.; Drewa, S.; Lasek, W.; Pilecki, S.; Junik, R.

    2005-01-01

    Splenosis is usually defined as an autotransplantation of lienal tissue in the abdomen or cest following trauma to the spleen and/or splenectomy. The authors present the case of patient 15 years after a splenectomy performed because of extensive abdominal trauma. A new computed tomographic (CT) scan of the abdomen revealed multiple homogenous nodules, different in size, spread in the abdomen. Their density was characteristic of spleen. Ultrasound examination revealed only the largest tumors, located close to the liver and apparently isoechogenic to it. Static scintigraphy and SPECT were performed to prove the presence of splenosis. After treating the patient with colloid sulfide, multiple foci of increased radioisotope accumulation were identified in the abdomen, extrahepatic at the same locations as the masses visible on the CT scans, which were comparable to splenic tissue. Nodules revealed during CT or abdominal US in patients previously treated by splenectomy require further imaging with static scintigraphy of the liver and spleen in order to confirm or exclude splenosis. (author)

  15. Transfer learning for bimodal biometrics recognition

    Science.gov (United States)

    Dan, Zhiping; Sun, Shuifa; Chen, Yanfei; Gan, Haitao

    2013-10-01

    Biometrics recognition aims to identify and predict new personal identities based on their existing knowledge. As the use of multiple biometric traits of the individual may enables more information to be used for recognition, it has been proved that multi-biometrics can produce higher accuracy than single biometrics. However, a common problem with traditional machine learning is that the training and test data should be in the same feature space, and have the same underlying distribution. If the distributions and features are different between training and future data, the model performance often drops. In this paper, we propose a transfer learning method for face recognition on bimodal biometrics. The training and test samples of bimodal biometric images are composed of the visible light face images and the infrared face images. Our algorithm transfers the knowledge across feature spaces, relaxing the assumption of same feature space as well as same underlying distribution by automatically learning a mapping between two different but somewhat similar face images. According to the experiments in the face images, the results show that the accuracy of face recognition has been greatly improved by the proposed method compared with the other previous methods. It demonstrates the effectiveness and robustness of our method.

  16. Heat transfer bibliography: russian works

    Energy Technology Data Exchange (ETDEWEB)

    Luikov, A V

    1965-02-01

    This bibliography of recent Russian publications in heat transfer is divided into the following categories: (1) books; (2) general; (3) experimental methods; (4) analytical calculation methods; (5) thermodynamics; (6) transfer processes involving phase conversions; ((7) transfer processes involving chemical conversions; (8) transfer processes involving very high velocities; (9) drying processes; (10) thermal properties of various materials, heat transfer agents and their determination methods; (11) high temperature physics and magneto- hydrodynamics; and (12) transfer processes in technological apparatuses. (357 refs.)

  17. Factors influencing detail detectability in radiologic imaging

    International Nuclear Information System (INIS)

    Gurvich, A.M.

    1985-01-01

    The detectability of various details is estimated quantitatively from the essential technical parameters of the imaging system and additional influencing factors including viewing of the image. The analysis implies the formation of the input radiation distribution (contrast formation, influence of kVp). Noise, image contrast (gamma), modulation transfer function and contrast threshold of the observer are of different influence on details of different size. Thus further optimization of imaging systems and their adaption to specific imaging tasks are facilitated

  18. Impact of ultrasound video transfer on the practice of ultrasound

    Science.gov (United States)

    Duerinckx, Andre J.; Hayrapetian, Alek S.; Grant, Edward G.; Valentino, Daniel J.; Rahbar, Darius; Kiszonas, Mike; Franco, Ricky; Melany, Michelle; Narin, Sherelle L.; Ragavendra, Nagesh

    1996-05-01

    Sonography can be highly dependent on real-time imaging and as such is highly physician intensive. Such situations arise mostly during complicated ultrasound radiology studies or echocardiology examinations. Under those circumstances it would be of benefit to transmit real-time images beyond the immediate area of the ultrasound laboratory when a physician is not on location. We undertook this study to determine if both static and dynamic image transfer to remote locations might be accomplished using an ultrafast ATM network and PACS. Image management of the local image files was performed by a commercial PACS from AGFA corporation. The local network was Ethernet based, and the global network was based on Asynchronous Transfer Mode (ATM, rates up to 100 Mbits/sec). Real-time image transfer involved two teaching hospitals, one of which had 2 separate ultrasound facilities. Radiologists consulted with technologists via telephone while the examinations were being performed. The applications of ATM network providing real time video for ultrasound imaging in a clinical environment and its potential impact on health delivery and clinical teaching. This technology increased technologist and physician productivity due to the elimination of commute time for physicians and waiting time for technologists and patients. Physician confidence in diagnosis increased compared to reviewing static images alone. This system provided instant access for radiologists to real-time scans from remote sites. Image quality and frame rate were equivalent to the original. The system increased productivity by allowing physicians to monitor studies at multiple sites simultaneously.

  19. Poutnictví, nebo turismus? Přehodnocení náboženských a sekulárních cest za nevšedností

    Directory of Open Access Journals (Sweden)

    Jan Kapusta

    2011-04-01

    Full Text Available The essay deals with the relationships among pilgrimage, travelling, ethnography, tourism and other forms of mobility. I argue that it is not useful to distinguish strictly between the categories of pilgrimage and tourism. Furthermore, I try to challenge the boundaries between religious and secular motion to attain more complex view of the matter. I utilize examples from San Giovanni Rotondo, Italy; San Marcos La Laguna, Guatemala; Mariazell, Austria; and the Viennese palace of Albertina to explore the multidimensionality of the subject and simultaneously to depict its similarities. The journeys to the extraordinary, unusual or exceptional experiences share some common aspects such as the power of metanarratives or the effect of psychosocial reinforcement. Here I focus on how the images and discourses are culturally constructed and used by pilgrims, tourists and travellers. Finally, I emphasize that the journeys provide psychic strengthening and social capital to the actors.

  20. Pediatric digital chest imaging.

    Science.gov (United States)

    Tarver, R D; Cohen, M; Broderick, N J; Conces, D J

    1990-01-01

    The Philips Computed Radiography system performs well with pediatric portable chest radiographs, handling the throughout of a busy intensive care service 24 hours a day. Images are excellent and routinely provide a conventional (unenhanced) image and an edge-enhanced image. Radiation dose is decreased by the lowered frequency of repeat examinations and the ability of the plates to respond to a much lower dose and still provide an adequate image. The high quality and uniform density of serial PCR portable radiographs greatly enhances diagnostic content of the films. Decreased resolution has not been a problem clinically. Image manipulation and electronic transfer to remote viewing stations appear to be helpful and are currently being evaluated further. The PCR system provides a marked improvement in pediatric portable chest radiology.

  1. Pediatric digital chest imaging

    International Nuclear Information System (INIS)

    Tarver, R.D.; Cohen, M.; Broderick, N.J.; Conces, D.J. Jr.

    1990-01-01

    The Philips Computed Radiography system performs well with pediatric portable chest radiographs, handling the throughout of a busy intensive care service 24 hours a day. Images are excellent and routinely provide a conventional (unenhanced) image and an edge-enhanced image. Radiation dose is decreased by the lowered frequency of repeat examinations and the ability of the plates to respond to a much lower dose and still provide an adequate image. The high quality and uniform density of serial PCR portable radiographs greatly enhances diagnostic content of the films. Decreased resolution has not been a problem clinically. Image manipulation and electronic transfer to remote viewing stations appear to be helpful and are currently being evaluated further. The PCR system provides a marked improvement in pediatric portable chest radiology

  2. The heat transfer mechanisms in fluidized beds; Laemmoensiirtomekanismit leijukerroksessa

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Blomster, A.M.; Kojola, H. [Helsinki Univ. of Technology, Espoo (Finland)

    1996-12-01

    The goal of the research project is to improve the accuracy of the heat transfer correlation in circulating fluidized beds and to define how the heat transfer is distributed in radiation and convection in the different parts of the fluidized bed. This will be carried out by studying the behaviour and heat transfer of the fluidized bed in the boundary layer near the wall. The total and radiative heat transfer as well as the particle concentration will be measured. Based on the data a correlation will be created. Two different measurement systems are used. The particle concentration is measured by a image-analysis system. A video camera and a Super VHS recorder are used to capture live images from the bed. The images are digitized and stored on a PC. The system has been used in previous research projects at our laboratory. In earlier projects all measurements have been carried out in cold environments. In this project the system will be modified for hot environments. The radiative heat transfer is measured by a radiative heat transfer probe connected to a PC via an A/D converter. The probe consists of a heat flow detector which is isolated from the bed by a sapphire window so that only the radiative part of the heat transfer is detected. The probe will be calibrated in a black body oven so that the effect of the conduction and the sapphire window can be separated. (author)

  3. Electrophoretic transfer protein zymography.

    Science.gov (United States)

    Pan, Daniel; Hill, Adam P; Kashou, Anthony; Wilson, Karl A; Tan-Wilson, Anna

    2011-04-15

    Zymography detects and characterizes proteolytic enzymes by electrophoresis of protease-containing samples into a nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel containing a copolymerized protein substrate. The usefulness of zymography for molecular weight determination and proteomic analysis is hampered by the fact that some proteases exhibit slower migration through a gel that contains substrate protein. This article introduces electrophoretic transfer protein zymography as one solution to this problem. In this technique, samples containing proteolytic enzymes are first resolved in nonreducing SDS-PAGE on a gel without protein substrate. The proteins in the resolving gel are then electrophoretically transferred to a receiving gel previously prepared with a copolymerized protein substrate. The receiving gel is then developed as a zymogram to visualize clear or lightly stained bands in a dark background. Band intensities are linearly related to the amount of protease, extending the usefulness of the technique so long as conditions for transfer and development of the zymogram are kept constant. Conditions of transfer, such as the pore sizes of resolving and receiving gels and the transfer time relative to the molecular weight of the protease, are explored. Copyright © 2011 Elsevier Inc. All rights reserved.

  4. University Technology Transfer

    Directory of Open Access Journals (Sweden)

    Mike Cox

    2004-09-01

    Full Text Available This article describes the experiences and general observations of the author at Heriot-Watt University and concerns the transfer of university technology for the purposes of commercialisation. Full commercial exploitation of a university invention generally requires transferring that technology into the industrial arena, usually either by formation of a new company or licensing into an existing company. Commercialisation activities need to be carried out in unison with the prime activities of the university of research and teaching. Responsibility for commercialising university inventions generally rests with a specific group within the university, typically referred to as the technology transfer group. Each technology transfer should be considered individually and appropriate arrangements made for that particular invention. In general, this transfer process involves four stages: identification, evaluation, protection and exploitation. Considerations under these general headings are outlined from a university viewpoint. A phased approach is generally preferred where possible for the evaluation, protection and exploitation of an invention to balance risk with potential reward. Evaluation of the potential opportunity for a university invention involves essentially the same considerations as for an industrial invention. However, there are a range of commercial exploitation routes and potential deals so that only general guidelines can be given. Naturally, the final deal achieved is that which can be negotiated. The potential rewards for the university and inventor are both financial (via licensing income and equity realisation and non-financial.

  5. Photoelectric transfer device

    Energy Technology Data Exchange (ETDEWEB)

    Shinomiya, Takuji; Murao, Fumihide

    1987-12-07

    Concerning the conventional photoelectric transfer device, a short-circuit current of photodiodes is switched over with MOS transistors. However, since the backgate voltage of the MOS transistor which is to be used as the switching element, is provided by the source voltage, the leakage current between the backgate and the source/drain/ channel is great and due to this leakage current, errors occur in the photoelectric transfer power output. Especially, when the leakage current of the photodiodes is small, the error becomes large. In order to solve the above problem, this invention aims at offering a photoelectric transfer device which can provide the high precision photoelectric transfer even the short-circuit current generated in the photodiodes is small and proposes a photoelectric transfer device in which the backgate voltage of the MOS transistor switching over the short-circuit current of the photodiodes is made equal to the electric potential of the mutually connected anodes (or cathodes) of the photodiodes. (3 figs)

  6. Heat and mass transfer

    CERN Document Server

    Karwa, Rajendra

    2017-01-01

    This textbook presents the classical treatment of the problems of heat transfer in an exhaustive manner with due emphasis on understanding of the physics of the problems. This emphasis is especially visible in the chapters on convective heat transfer. Emphasis is laid on the solution of steady and unsteady two-dimensional heat conduction problems. Another special feature of the book is a chapter on introduction to design of heat exchangers and their illustrative design problems. A simple and understandable treatment of gaseous radiation has been presented. A special chapter on flat plate solar air heater has been incorporated that covers thermo-hydraulic modeling and simulation. The chapter on mass transfer has been written looking specifically at the needs of the students of mechanical engineering. The book includes a large number and variety of solved problems with supporting line diagrams. The author has avoided duplicating similar problems, while incorporating more application-based examples. All the end-...

  7. Quadrupolar transfer pathways

    Science.gov (United States)

    Antonijevic, Sasa; Bodenhausen, Geoffrey

    2006-06-01

    A set of graphical conventions called quadrupolar transfer pathways is proposed to describe a wide range of experiments designed for the study of quadrupolar nuclei with spin quantum numbers I = 1, 3/2, 2, 5/2, etc. These pathways, which inter alea allow one to appreciate the distinction between quadrupolar and Zeeman echoes, represent a generalization of the well-known coherence transfer pathways. Quadrupolar transfer pathways not merely distinguish coherences with different orders -2 I ⩽ p ⩽ +2 I, but allow one to follow the fate of coherences associated with single transitions that have the same coherence orderp=mIr-mIs but can be distinguished by a satellite orderq=(mIr)2-(mIs)2.

  8. Thermal radiation heat transfer

    CERN Document Server

    Howell, John R; Mengüç, M Pinar

    2011-01-01

    Providing a comprehensive overview of the radiative behavior and properties of materials, the fifth edition of this classic textbook describes the physics of radiative heat transfer, development of relevant analysis methods, and associated mathematical and numerical techniques. Retaining the salient features and fundamental coverage that have made it popular, Thermal Radiation Heat Transfer, Fifth Edition has been carefully streamlined to omit superfluous material, yet enhanced to update information with extensive references. Includes four new chapters on Inverse Methods, Electromagnetic Theory, Scattering and Absorption by Particles, and Near-Field Radiative Transfer Keeping pace with significant developments, this book begins by addressing the radiative properties of blackbody and opaque materials, and how they are predicted using electromagnetic theory and obtained through measurements. It discusses radiative exchange in enclosures without any radiating medium between the surfaces-and where heat conduction...

  9. Diffusion and mass transfer

    CERN Document Server

    Vrentas, James S

    2013-01-01

    The book first covers the five elements necessary to formulate and solve mass transfer problems, that is, conservation laws and field equations, boundary conditions, constitutive equations, parameters in constitutive equations, and mathematical methods that can be used to solve the partial differential equations commonly encountered in mass transfer problems. Jump balances, Green’s function solution methods, and the free-volume theory for the prediction of self-diffusion coefficients for polymer–solvent systems are among the topics covered. The authors then use those elements to analyze a wide variety of mass transfer problems, including bubble dissolution, polymer sorption and desorption, dispersion, impurity migration in plastic containers, and utilization of polymers in drug delivery. The text offers detailed solutions, along with some theoretical aspects, for numerous processes including viscoelastic diffusion, moving boundary problems, diffusion and reaction, membrane transport, wave behavior, sedime...

  10. Intergenerational Knowledge Transfer

    International Nuclear Information System (INIS)

    Grover, R.B.

    2016-01-01

    Full text: Institutions of higher education and universities have been at the forefront of intergenerational knowledge transfer. Their role has gone through evolution and several ideas of the university co-exist. Factors like the squeeze on public funding of higher education across nations, exhortation by governments to value work-based learning as a part of higher education and demand for graduates ready to start working immediately on joining a workplace, are making it necessary to further evolve the classical approach towards intergenerational knowledge transfer. The paper presents a framework that has been evolved in India to meet the requirements of intergenerational knowledge transfer. It essentially integrates a workplace and a university in a single entity similar to the practice in medical education. (author

  11. Charge transfer in astrophysical nebulae

    International Nuclear Information System (INIS)

    Shields, G.A.

    1990-01-01

    Charge transfer has become a standard ingredient in models of ionized nebulae, supernovae remnants and active galactic nuclei. Charge transfer rate coefficients and the physics of ionized nebulae are considered. Charge transfer is applied to the ionization structure and line emission of ionized nebulae. Photoionized nebulae observations are used to test theoretical predictions of charge transfer rates. (author)

  12. Engineering heat transfer

    International Nuclear Information System (INIS)

    Welty, J.R.

    1974-01-01

    The basic concepts of heat transfer are covered with special emphasis on up-to-date techniques for formulating and solving problems in the field. The discussion progresses logically from phenomenology to problem solving, and treats numerical, integral, and graphical methods as well as traditional analytical ones. The book is unique in its thorough coverage of the fundamentals of numerical analysis appropriate to solving heat transfer problems. This coverage includes several complete and readable examples of numerical solutions, with discussions and interpretations of results. The book also contains an appendix that provides students with physical data for often-encountered materials. An index is included. (U.S.)

  13. Transferences of Purkinje systems

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2011-12-01

    Full Text Available The transferences of heterocentric astigmatic Purkinje systems are special: submatrices B and C, that is, the disjugacy and the divergence of the system, are symmetric and submatrix D (the divarication is the transpose of submatrix A (the dilation.  It is the primary purpose of this paper to provide a proof.  The paper also derives other relationships among the fundamental properties and compact expressions for the transference and optical axis locator of a Purkinje system. (S Afr Optom 2011 70(2 57-60

  14. Elementary heat transfer analysis

    CERN Document Server

    Whitaker, Stephen; Hartnett, James P

    1976-01-01

    Elementary Heat Transfer Analysis provides information pertinent to the fundamental aspects of the nature of transient heat conduction. This book presents a thorough understanding of the thermal energy equation and its application to boundary layer flows and confined and unconfined turbulent flows. Organized into nine chapters, this book begins with an overview of the use of heat transfer coefficients in formulating the flux condition at phase interface. This text then explains the specification as well as application of flux boundary conditions. Other chapters consider a derivation of the tra

  15. Cernavoda NPP Knowledge Transfer

    International Nuclear Information System (INIS)

    Valache, C. M.

    2016-01-01

    Full text: The paper presents a description of the Knowledge Transfer (KT) process implemented at Cernavoda NPP, its designing and implementation. It is underlined that applying a KT approach should improve the value of existing processes of the organization through: • Identifying business, operational and safety risks due to knowledge gaps, • Transfer of knowledge from the ageing workforce to the peers and/or the organization, • Continually learning from successes and failures of individual or teams, • Convert tacit knowledge to explicit knowledge, • Improving operational and safety performance through creating both new knowledge and better access to existing knowledge. (author

  16. Knowledge Transfers in IJVs

    DEFF Research Database (Denmark)

    Park, Chansoo; Vertinsky, Ilan; Minbaeva, Dana

    firms to their international joint ventures (IJVs) in South Korea. We developed a theoretical model that examines the impacts of the knowledge senders¡¯ disseminative capacities on knowledge transfer to IJVs. We tested our theory with data from 199 IJVs in South Korea. We found that the willingness...... of parent firms to share knowledge is manifested in an increased capacity to articulate and codify knowledge and create opportunities to transfer this knowledge. Mediated by the effective use of organizational communication channels, articulation and codification capabilities have a significant impact...

  17. Ariane transfer vehicle scenario

    Science.gov (United States)

    Deutscher, Norbert; Cougnet, Claude

    1990-10-01

    ESA's Ariane Transfer Vehicle (ATV) is a vehicle design concept for the transfer of payloads from Ariane 5 launch vehicle orbit insertion to a space station, on the basis of the Ariane 5 program-developed Upper Stage Propulsion Module and Vehicle Equipment Bay. The ATV is conceived as a complement to the Hermes manned vehicle for lower cost unmanned carriage of logistics modules and other large structural elements, as well as waste disposal. It is also anticipated that the ATV will have an essential role in the building block transportation logistics of any prospective European space station.

  18. NASA Technology Transfer System

    Science.gov (United States)

    Tran, Peter B.; Okimura, Takeshi

    2017-01-01

    NTTS is the IT infrastructure for the Agency's Technology Transfer (T2) program containing 60,000+ technology portfolio supporting all ten NASA field centers and HQ. It is the enterprise IT system for facilitating the Agency's technology transfer process, which includes reporting of new technologies (e.g., technology invention disclosures NF1679), protecting intellectual properties (e.g., patents), and commercializing technologies through various technology licenses, software releases, spinoffs, and success stories using custom built workflow, reporting, data consolidation, integration, and search engines.

  19. Beyond unidirectional knowledge transfer

    DEFF Research Database (Denmark)

    Ulhøi, John Parm; Neergaard, Helle; Bjerregaard, Toke

    2012-01-01

    Using theory on technology transfer and on trust and an indepth study of nine university departments and nineteen science-based small and medium-sized enterprises (SMEs), the authors explore the nature and direction of knowledge flows during university-industry R&D collaboration. More specifically......, they examine the nature and direction of R&D technological knowledge transfer in collaborations between universities and science-based SMEs and the primary mechanisms regulating such collaborations. The findings suggest that these collaborations are highly recursive processes of technological knowledge...

  20. Energy transfer in plasmonic systems

    International Nuclear Information System (INIS)

    Pustovit, Vitaliy N; Urbas, Augustine M; Shahbazyan, Tigran V

    2014-01-01

    We present our results on energy transfer between donor and acceptor molecules or quantum dots near a plasmonic nanoparticle. In such systems, the Förster resonance energy transfer is strongly modified due to plasmon-mediated coupling between donors and acceptors. The transfer efficiency is determined by a competition between transfer, radiation and dissipation that depends sensitively on system parameters. When donor and accepror spectral bands overlap with dipole surface plasmon resonance, the dominant transfer mechanism is through plasmon-enhanced radiative coupling. When transfer takes place from an ensemble of donors to an acceptor, a cooperative amplification of energy transfer takes place in a wide range of system parameters. (paper)

  1. Heat transfer fluids containing nanoparticles

    Science.gov (United States)

    Singh, Dileep; Routbort, Jules; Routbort, A.J.; Yu, Wenhua; Timofeeva, Elena; Smith, David S.; France, David M.

    2016-05-17

    A nanofluid of a base heat transfer fluid and a plurality of ceramic nanoparticles suspended throughout the base heat transfer fluid applicable to commercial and industrial heat transfer applications. The nanofluid is stable, non-reactive and exhibits enhanced heat transfer properties relative to the base heat transfer fluid, with only minimal increases in pumping power required relative to the base heat transfer fluid. In a particular embodiment, the plurality of ceramic nanoparticles comprise silicon carbide and the base heat transfer fluid comprises water and water and ethylene glycol mixtures.

  2. Thickness-Independent Ultrasonic Imaging Applied to Abrasive Cut-Off Wheels: An Advanced Aerospace Materials Characterization Method for the Abrasives Industry. A NASA Lewis Research Center Technology Transfer Case History

    Science.gov (United States)

    Roth, Don J.; Farmer, Donald A.

    1998-01-01

    Abrasive cut-off wheels are at times unintentionally manufactured with nonuniformity that is difficult to identify and sufficiently characterize without time-consuming, destructive examination. One particular nonuniformity is a density variation condition occurring around the wheel circumference or along the radius, or both. This density variation, depending on its severity, can cause wheel warpage and wheel vibration resulting in unacceptable performance and perhaps premature failure of the wheel. Conventional nondestructive evaluation methods such as ultrasonic c-scan imaging and film radiography are inaccurate in their attempts at characterizing the density variation because a superimposing thickness variation exists as well in the wheel. In this article, the single transducer thickness-independent ultrasonic imaging method, developed specifically to allow more accurate characterization of aerospace components, is shown to precisely characterize the extent of the density variation in a cut-off wheel having a superimposing thickness variation. The method thereby has potential as an effective quality control tool in the abrasives industry for the wheel manufacturer.

  3. Image Gallery

    Science.gov (United States)

    ... R S T U V W X Y Z Image Gallery Share: The Image Gallery contains high-quality digital photographs available from ... Select a category below to view additional thumbnail images. Images are available for direct download in 2 ...

  4. Transfer of manufacturing units

    DEFF Research Database (Denmark)

    Madsen, Erik Skov; Riis, Jens Ove; Sørensen, Brian Vejrum

    2008-01-01

    The ongoing and unfolding relocation of activities is one of the major trends, that calls for attention in the domain of operations management. In particular, prescriptive models outlining: stages of the process, where to locate, and how to establish the new facilities have been studied, while...... and dilemmas to be addressed when transferring manufacturing units....

  5. Enhanced Condensation Heat Transfer

    Science.gov (United States)

    Rose, John Winston

    The paper gives some personal observations on various aspects of enhanced condensation heat transfer. The topics discussed are external condensation (horizontal low-finned tubes and wire-wrapped tubes), internal condensation (microfin tubes and microchannels) and Marangoni condensation of binary mixtures.

  6. Investigating Wireless Power Transfer

    Science.gov (United States)

    St. John, Stuart A.

    2017-01-01

    Understanding Physics is a great end in itself, but is also crucial to keep pace with developments in modern technology. Wireless power transfer, known to many only as a means to charge electric toothbrushes, will soon be commonplace in charging phones, electric cars and implanted medical devices. This article outlines how to produce and use a…

  7. Knowledge Management and Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Sennanye, D.M.; Thugwane, S.J.; Rasweswe, M.A. [South African Young Nuclear Professionals Society, South African Nuclear Energy Cooperation, National Nuclear Regulator, P O Box 7106, Centurion 0046 (South Africa)

    2008-07-01

    Knowledge management has become an important concept in the nuclear industry globally. This has been driven by the fact that new reactors are commissioned and some are decommissioned. Since most old experts are near retirement then there is a need to capture the nuclear knowledge and expertise and transfer it to the new generation. Knowledge transfer is one of the important building blocks of knowledge management. Processes and strategies need to be developed in order to transfer this knowledge. South African Young Nuclear Professionals Society (SAYNPS) has established a document to address strategies that can be used to close the knowledge gap between the young less experienced and experts in the field. This action will help the young generation to participate in knowledge management. The major challenges will be the willingness of the experts to share and making sure that all knowledge is captured, stored and kept up to date. The paper presents the SAYNPS point of view with regard to knowledge transfer. (authors)

  8. Science transfer for development

    International Nuclear Information System (INIS)

    Salam, A.

    1985-01-01

    Despite the recent realisation that science and technology are the sustenance and major hope for economic betterment, the third world, barring a few countries like Argentina, Brazil, China and India, has taken to science - as distinct from technology - as only a marginal activity. This is also true of the aid - giving agencies of the richer countries, of the agencies of the UN and also unfortunately of the scientific communities of the developed countries which might naturally be expected to be the Third World's foremost allies. Policy makers, prestigious commissions (like the Brandt Commission) as well as aid-givers, speak uniformly of problems of technology transfer to the developing countries as if that is all that is involved. Very few within the developing world appear to stress that for long term effectiveness, technology transfers must always be accompanied by science transfers; that the science of today is the technology of tomorrow. Science transfer is effected by and to communities of scientists. Such communities (in developing countries) need building up to a critical size in their human resources and infrastructure. This building up calls for wise science policies, with long term commitment, generous patronage, self governance and free international contacts. Further, in our countries, the high level scientist must be allowed to play a role in nation building as an equal partner to the professional planner, the economist and the technologist. Few developing countries have promulgated such policies: few aid agencies have taken it as their mandate to encourage and help build up the scientific infrastructure. (author)

  9. Transfer metrics analytics project

    CERN Document Server

    Matonis, Zygimantas

    2016-01-01

    This report represents work done towards predicting transfer rates/latencies on Worldwide LHC Computing Grid (WLCG) sites using Machine Learning techniques. Topic covered are technologies used for the project, data preparation for ML suitable format and attribute selection as well as a comparison of different ML algorithms.

  10. Feed tank transfer requirements

    International Nuclear Information System (INIS)

    Freeman-Pollard, J.R.

    1998-01-01

    This document presents a definition of tank turnover; DOE responsibilities; TWRS DST permitting requirements; TWRS Authorization Basis (AB) requirements; TWRS AP Tank Farm operational requirements; unreviewed safety question (USQ) requirements; records and reporting requirements, and documentation which will require revision in support of transferring a DST in AP Tank Farm to a privatization contractor for use during Phase 1B

  11. Electron transfer to sulfides:

    International Nuclear Information System (INIS)

    Meneses, Ana Belen; Antonello, Sabrina; Arevalo, Maria Carmen; Maran, Flavio

    2005-01-01

    The problem of characterizing the steps associated with the dissociative reduction of sulfides has been addressed. The electrochemical reduction of diphenylmethyl para-methoxyphenyl sulfide in N,N-dimethylformamide, on both glassy carbon and mercury electrodes, was chosen as a test system. The electrode process involves the slow heterogeneous outer-sphere electron transfer to the sulfide, the fast cleavage of the C-S bond, the reduction of the ensuing carbon radical, and the self-protonation triggered by the generation of the strong base Ph 2 CH - . The latter reaction is rather slow, in agreement with the large intrinsic barriers characterizing proton transfers between CH-acids and carbon bases. The dissociative reduction was studied in the presence of an exogenous acid. The results, obtained by convolution analysis, point to a stepwise DET mechanism in which the ET step is accompanied by rather large reorganization energy. Similar results were obtained on both electrode materials. Analysis of the heterogeneous electron transfer and associated C-S bond cleavage indicate that the reduction of this and other sulfides lies between the stepwise dissociative electron transfers leading to the formation of stiff π* radical anions and those going through the intermediacy of loose σ* radical anions

  12. Nonadiabatic anharmonic electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, P. P. [Molecular Physics Research, 6547 Kristina Ursula Court, Falls Church, Virginia 22044 (United States)

    2013-03-28

    The effect of an inner sphere, local mode vibration on an electron transfer is modeled using the nonadiabatic transition probability (rate) expression together with both the anharmonic Morse and the harmonic oscillator potential. For an anharmonic inner sphere mode, a variational analysis uses harmonic oscillator basis functions to overcome the difficulties evaluating Morse-model Franck-Condon overlap factors. Individual matrix elements are computed with the use of new, fast, robust, and flexible recurrence relations. The analysis therefore readily addresses changes in frequency and/or displacement of oscillator minimums in the different electron transfer states. Direct summation of the individual Boltzmann weighted Franck-Condon contributions avoids the limitations inherent in the use of the familiar high-temperature, Gaussian form of the rate constant. The effect of harmonic versus anharmonic inner sphere modes on the electron transfer is readily seen, especially in the exoergic, inverted region. The behavior of the transition probability can also be displayed as a surface for all temperatures and values of the driving force/exoergicity {Delta}=-{Delta}G. The temperature insensitivity of the transfer rate is clearly seen when the exoergicity equals the collective reorganization energy ({Delta}={Lambda}{sub s}) along a maximum ln (w) vs. {Delta} ridge of the surface. The surface also reveals additional regions for {Delta} where ln (w) appears to be insensitive to temperature, or effectively activationless, for some kinds of inner sphere contributions.

  13. Understanding Transfer of Training.

    Science.gov (United States)

    Brown, Mark G.

    1983-01-01

    Stresses the difficulty of "maintenance" of newly learned behaviors by reinforcement and feedback on the job and proposes an alternative means of promoting transfer of training--establishing rule-governed behavior. Some ways of establishing rules in training are listed and discussed, including use of behavior-modeling and other…

  14. Transfer Pricing Principles

    DEFF Research Database (Denmark)

    Jensen, Dennis Ramsdahl

    Konferencebidraget indeholder en kritisk analyse af transfer pricing reglerne på henholdsvis moms og indkomstskatterettens område med henblik på en diskussion af, det er hensigtsmæssigt med en harmonisering af reglerne på tværs af de to retsområder...

  15. Knowledge Management and Transfer

    International Nuclear Information System (INIS)

    Sennanye, D.M.; Thugwane, S.J.; Rasweswe, M.A.

    2008-01-01

    Knowledge management has become an important concept in the nuclear industry globally. This has been driven by the fact that new reactors are commissioned and some are decommissioned. Since most old experts are near retirement then there is a need to capture the nuclear knowledge and expertise and transfer it to the new generation. Knowledge transfer is one of the important building blocks of knowledge management. Processes and strategies need to be developed in order to transfer this knowledge. South African Young Nuclear Professionals Society (SAYNPS) has established a document to address strategies that can be used to close the knowledge gap between the young less experienced and experts in the field. This action will help the young generation to participate in knowledge management. The major challenges will be the willingness of the experts to share and making sure that all knowledge is captured, stored and kept up to date. The paper presents the SAYNPS point of view with regard to knowledge transfer. (authors)

  16. Supervised Transfer Sparse Coding

    KAUST Repository

    Al-Shedivat, Maruan

    2014-07-27

    A combination of the sparse coding and transfer learn- ing techniques was shown to be accurate and robust in classification tasks where training and testing objects have a shared feature space but are sampled from differ- ent underlying distributions, i.e., belong to different do- mains. The key assumption in such case is that in spite of the domain disparity, samples from different domains share some common hidden factors. Previous methods often assumed that all the objects in the target domain are unlabeled, and thus the training set solely comprised objects from the source domain. However, in real world applications, the target domain often has some labeled objects, or one can always manually label a small num- ber of them. In this paper, we explore such possibil- ity and show how a small number of labeled data in the target domain can significantly leverage classifica- tion accuracy of the state-of-the-art transfer sparse cod- ing methods. We further propose a unified framework named supervised transfer sparse coding (STSC) which simultaneously optimizes sparse representation, domain transfer and classification. Experimental results on three applications demonstrate that a little manual labeling and then learning the model in a supervised fashion can significantly improve classification accuracy.

  17. Image quality (IQ) guided multispectral image compression

    Science.gov (United States)

    Zheng, Yufeng; Chen, Genshe; Wang, Zhonghai; Blasch, Erik

    2016-05-01

    Image compression is necessary for data transportation, which saves both transferring time and storage space. In this paper, we focus on our discussion on lossy compression. There are many standard image formats and corresponding compression algorithms, for examples, JPEG (DCT -- discrete cosine transform), JPEG 2000 (DWT -- discrete wavelet transform), BPG (better portable graphics) and TIFF (LZW -- Lempel-Ziv-Welch). The image quality (IQ) of decompressed image will be measured by numerical metrics such as root mean square error (RMSE), peak signal-to-noise ratio (PSNR), and structural Similarity (SSIM) Index. Given an image and a specified IQ, we will investigate how to select a compression method and its parameters to achieve an expected compression. Our scenario consists of 3 steps. The first step is to compress a set of interested images by varying parameters and compute their IQs for each compression method. The second step is to create several regression models per compression method after analyzing the IQ-measurement versus compression-parameter from a number of compressed images. The third step is to compress the given image with the specified IQ using the selected compression method (JPEG, JPEG2000, BPG, or TIFF) according to the regressed models. The IQ may be specified by a compression ratio (e.g., 100), then we will select the compression method of the highest IQ (SSIM, or PSNR). Or the IQ may be specified by a IQ metric (e.g., SSIM = 0.8, or PSNR = 50), then we will select the compression method of the highest compression ratio. Our experiments tested on thermal (long-wave infrared) images (in gray scales) showed very promising results.

  18. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Lu, H. Peter [Bowling Green State Univ., Bowling Green, OH (United States). Dept. of Chemistry and Center for Photochemical Sciences

    2017-11-28

    This project is focused on the use of single-molecule high spatial and temporal resolved techniques to study molecular dynamics in condensed phase and at interfaces, especially, the complex reaction dynamics associated with electron and energy transfer rate processes. The complexity and inhomogeneity of the interfacial ET dynamics often present a major challenge for a molecular level comprehension of the intrinsically complex systems, which calls for both higher spatial and temporal resolutions at ultimate single-molecule and single-particle sensitivities. Combined single-molecule spectroscopy and electrochemical atomic force microscopy approaches are unique for heterogeneous and complex interfacial electron transfer systems because the static and dynamic inhomogeneities can be identified and characterized by studying one molecule at a specific nanoscale surface site at a time. The goal of our project is to integrate and apply these spectroscopic imaging and topographic scanning techniques to measure the energy flow and electron flow between molecules and substrate surfaces as a function of surface site geometry and molecular structure. We have been primarily focusing on studying interfacial electron transfer under ambient condition and electrolyte solution involving both single crystal and colloidal TiO2 and related substrates. The resulting molecular level understanding of the fundamental interfacial electron transfer processes will be important for developing efficient light harvesting systems and broadly applicable to problems in fundamental chemistry and physics. We have made significant advancement on deciphering the underlying mechanism of the complex and inhomogeneous interfacial electron transfer dynamics in dyesensitized TiO2 nanoparticle systems that strongly involves with and regulated by molecule-surface interactions. We have studied interfacial electron transfer on TiO2 nanoparticle surfaces by using ultrafast single

  19. Image quality in mammography

    International Nuclear Information System (INIS)

    Haus, A.G.; Doi, K.; Metz, C.E.; Bernstein, J.

    1976-01-01

    In mammography, image quality is a function of the shape, size, and x-ray absorption properties of the anatomic part to be radiographed and of the lesion to be detected; it also depends on geometric unsharpness, and the resolution, characteristic curve and noise properties of the recording system. X-ray energy spectra, modulation transfer functions, Wiener spectra, characteristic and gradient curves, and radiographs of a breast phantom and of a resected breast specimen containing microcalcifications are used in a review of some current considerations of the factors, and the complex relationship among factors, that affect image quality in mammography. Image quality and patient radiation exposure in mammography are interrelated. An approach to the problem of evaluating the trade-off between diagnostic certainty and the cost or risk of performing a breast imaging procedure is discussed

  20. Restoration of longitudinal images.

    Science.gov (United States)

    Hu, Y; Frieden, B R

    1988-01-15

    In this paper, a method of restoring longitudinal images is developed. By using the transfer function for longitudinal objects, and inverse filtering, a longitudinal image may be restored. The Fourier theory and sampling theorems for transverse images cannot be used directly in the longitudinal case. A modification and reasonable approximation are introduced. We have numerically established a necessary relationship between just-resolved longitudinal separation (after inverse filtering), noise level, and the taking conditions of object distance and lens diameter. An empirical formula is also found to well-fit the computed results. This formula may be of use for designing optical systems which are to image longitudinal details, such as in robotics or microscopy.

  1. Processing computed tomography images by using personal computer

    International Nuclear Information System (INIS)

    Seto, Kazuhiko; Fujishiro, Kazuo; Seki, Hirofumi; Yamamoto, Tetsuo.

    1994-01-01

    Processing of CT images was attempted by using a popular personal computer. The program for image-processing was made with C compiler. The original images, acquired with CT scanner (TCT-60A, Toshiba), were transferred to the computer by 8-inch flexible diskette. Many fundamental image-processing, such as displaying image to the monitor, calculating CT value and drawing the profile curve. The result showed that a popular personal computer had ability to process CT images. It seemed that 8-inch flexible diskette was still useful medium of transferring image data. (author)

  2. Transfer of radiocesium in the fruit tree

    International Nuclear Information System (INIS)

    Takata, Daisuke

    2013-01-01

    After Fukushima Nuclear Power Plant Accident (Mar. 2011), the author has investigated the transfer of radiocesium (rCs) mainly in peach trees under the actual and cultivating conditions in Fukushima and Tokyo areas, of which results are given with their discussion herein. There are 2 routes of the transfer through the root absorbing the soil rCs originally fallen on the ground and through the aboveground organs absorbing the directly attached rCs on them. The latter attachment includes one on the old branch and main stem existed before the Accident, and another, on the leaf, young shoot and fruit (pericarp) absent at the Accident. Experimental data of peach tree with/without a ground cover show that in the year of the Accident (2011), rCs transfer in the tree body through the aboveground organs was superior to that through the root, and this was also confirmed in the grape tree. Analysis with the imaging plate revealed that a quite high level of rCs was present in the outer thin layer of the bark and in the lenticel, which was conceived to be the possible route of transfer in the tree body. rCs levels on fresh organs like pericarp were lowered by rinsing, suggesting that the nuclide was movable on the old organs to be transferred in new ones. When the tree grown at the high dose area was dug up for its root to be rinsed and partly cut and then the tree was cultivated in non-contaminated soil, the newly shot root contained the higher level of rCs than the leaf, of which mechanism is under investigation. rCs transfer in the tree from the soil and space, and reverse distribution possibly occur: the both sides are to be further investigated qualitatively and quantitatively. (T.T.)

  3. Evaluating imaging devices

    International Nuclear Information System (INIS)

    Rollo, F.D.

    1977-01-01

    The performance of any imaging device depends on two principal factors inherent to the device, namely, plane sensitivity and spatial resolution. These factors may be defined as follows: plane sensitivity is the counts per second recorded by the imaging device for each disintegration per second per square centimeter occurring within a plane sheet of radioactivity. Spatial resolution may be defined as the fidelity with which the imaging device reproduces the activity distribution of an object in the image plane. In all imaging devices, a trade-off exists between these two parameters; that is, as sensitivity improves, spatial resolution is degraded, and vice versa. Therefore, to fully evaluate an imaging system a technique should be selected that measures both parameters and reflects the trade-off between the two. In addition, the method should approximate the clinical problem, namely, the detection of a focal lesion within an activity distribution. Several methods have been described to evaluate nuclear imaging devices. The more common techniques include the use of organ phantoms, bar phantoms, line-spread functions, modulation transfer functions, contrast efficiency functions, and performance index functions. Each of these techniques is briefly described in this chapter, and their advantages and disadvantages are discussed. In addition, a phantom that can be used to simply and completely measure overall imaging system performance is described

  4. Image Transmission Studies

    Science.gov (United States)

    Blaine, G. James; Hill, Rexford L.; Rueter, Allen P.; Senol, Evren; Studt, James W.

    1988-06-01

    Radiological PACS image sizes and desired retrieval response times demand high-bandwidth communication networks. Local area network technology at speeds higher that 10 Megabits/second (IEEE 802.3) have not achieved standardization nor production volume. Our current PACS experiments are based on a three-level subnet approach using 10 Mb/s Ethernet channels. An Ethernet channel is shown to support image transfers at an average throughput of 3 Mb/s. Preliminary measurements and simulation results suggest that traffic from as many as two-to-three archives can be supported on the same channel.

  5. Image transmission studies

    International Nuclear Information System (INIS)

    Blaine, G.J.; Hill, R.L.; Rueter, A.P.; Senol, E.; Studt, J.W.

    1988-01-01

    This paper discusses radiological PACS image sizes and desired retrieval response time that demand high-bandwidth communication networks. Local area network technology at speeds higher that 10 Megabits/second (IEEE 802.3) have not achieved standardization nor production volume. The authors describe current PACS experiments based on a three-level subnet approach using 10 Mb/s Ethernet channels. An Ethernet channel is shown to support image transfers at an average throughput of 3 Mb/s. Preliminary measurements and simulation results suggest that traffic from as many as two-to-three archives can be supported on the same channel

  6. Gas transfer in a bubbly wake flow

    Science.gov (United States)

    Karn, A.; Gulliver, J. S.; Monson, G. M.; Ellis, C.; Arndt, R. E. A.; Hong, J.

    2016-05-01

    The present work reports simultaneous bubble size and gas transfer measurements in a bubbly wake flow of a hydrofoil, designed to be similar to a hydroturbine blade. Bubble size was measured by a shadow imaging technique and found to have a Sauter mean diameter of 0.9 mm for a reference case. A lower gas flow rate, greater liquid velocities, and a larger angle of attack all resulted in an increased number of small size bubbles and a reduced weighted mean bubble size. Bubble-water gas transfer is measured by the disturbed equilibrium technique. The gas transfer model of Azbel (1981) is utilized to characterize the liquid film coefficient for gas transfer, with one scaling coefficient to reflect the fact that characteristic turbulent velocity is replaced by cross-sectional mean velocity. The coefficient was found to stay constant at a particular hydrofoil configuration while it varied within a narrow range of 0.52-0.60 for different gas/water flow conditions.

  7. Wireless power transfer system

    Science.gov (United States)

    Wu, Hunter; Sealy, Kylee; Gilchrist, Aaron

    2016-02-23

    A system includes a first stage of an inductive power transfer system with an LCL load resonant converter with a switching section, an LCL tuning circuit, and a primary receiver pad. The IPT system includes a second stage with a secondary receiver pad, a secondary resonant circuit, a secondary rectification circuit, and a secondary decoupling converter. The secondary receiver pad connects to the secondary resonant circuit. The secondary resonant circuit connects to the secondary rectification circuit. The secondary rectification circuit connects to the secondary decoupling converter. The second stage connects to a load. The load includes an energy storage element. The second stage and load are located on a vehicle and the first stage is located at a fixed location. The primary receiver pad wirelessly transfers power to the secondary receiver pad across a gap when the vehicle positions the secondary receiver pad with respect to the primary receiver pad.

  8. Knowledge Transfers following Acquisition

    DEFF Research Database (Denmark)

    Gammelgaard, Jens

    2001-01-01

    Prior relations between the acquiring firm and the target company pave the way for knowledge transfers subsequent to the acquisitions. One major reason is that through the market-based relations the two actors build up mutual trust and simultaneously they learn how to communicate. An empirical...... study of 54 Danish acquisitions taking place abroad from 1994 to 1998 demonstrated that when there was a high level of trust between the acquiring firm and the target firm before the take-over, then medium and strong tie-binding knowledge transfer mechanisms, such as project groups and job rotation......, were used more intensively. Further, the degree of stickiness was significantly lower in the case of prior trust-based relations....

  9. CURRENT TRANSFER SYSTEMS

    Science.gov (United States)

    Watt, D.A.

    1956-07-01

    A current transfer system is described for transferring current between a rotating member and a co-axial stationary member. The particular area of application for the invention is in connection with homopolar generators where a low voltage and high current are generated. The current tramsfer system of the invention comprises a rotor member and a co-axial stator member wherein one of the members is shaped to provide a circumferential surface concave in section and the other member is shaped to have a peripheral portion in close proximity to the surface, whereby a liquid metal can be stably supported between the two members when they are moving relative to one another to establish an electrical conducting path between the members.

  10. Two-dimensional pixel image lag simulation and optimization in a 4-T CMOS image sensor

    Energy Technology Data Exchange (ETDEWEB)

    Yu Junting; Li Binqiao; Yu Pingping; Xu Jiangtao [School of Electronics Information Engineering, Tianjin University, Tianjin 300072 (China); Mou Cun, E-mail: xujiangtao@tju.edu.c [Logistics Management Office, Hebei University of Technology, Tianjin 300130 (China)

    2010-09-15

    Pixel image lag in a 4-T CMOS image sensor is analyzed and simulated in a two-dimensional model. Strategies of reducing image lag are discussed from transfer gate channel threshold voltage doping adjustment, PPD N-type doping dose/implant tilt adjustment and transfer gate operation voltage adjustment for signal electron transfer. With the computer analysis tool ISE-TCAD, simulation results show that minimum image lag can be obtained at a pinned photodiode n-type doping dose of 7.0 x 10{sup 12} cm{sup -2}, an implant tilt of -2{sup 0}, a transfer gate channel doping dose of 3.0 x 10{sup 12} cm{sup -2} and an operation voltage of 3.4 V. The conclusions of this theoretical analysis can be a guideline for pixel design to improve the performance of 4-T CMOS image sensors. (semiconductor devices)

  11. Feed tank transfer requirements

    International Nuclear Information System (INIS)

    Freeman-Pollard, J.R.

    1998-01-01

    This document presents a definition of tank turnover. Also, DOE and PC responsibilities; TWRS DST permitting requirements; TWRS Authorization Basis (AB) requirements; TWRS AP Tank Farm operational requirements; unreviewed safety question (USQ) requirements are presented for two cases (i.e., tank modifications occurring before tank turnover and tank modification occurring after tank turnover). Finally, records and reporting requirements, and documentation which will require revision in support of transferring a DST in AP Tank Farm to a privatization contractor are presented

  12. Heat Transfer Analogies

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, A

    1965-11-15

    This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table.

  13. Heat Transfer Analogies

    International Nuclear Information System (INIS)

    Bhattacharyya, A.

    1965-11-01

    This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table

  14. Technology transfer for development

    International Nuclear Information System (INIS)

    Abraham, D.

    1990-07-01

    The IAEA has developed a multifaceted approach to ensure that assistance to Member States results in assured technology transfer. Through advice and planning, the IAEA helps to assess the costs and benefits of a given technology, determine the basic requirements for its efficient use in conditions specific to the country, and prepare a plan for its introduction. This report describes in brief the Technical Co-operation Programmes

  15. Heat transfer. V. 1

    International Nuclear Information System (INIS)

    1992-01-01

    This volume contains the 4 key-note lectures and 83 of the 148 papers presented at the 3rd UK National Conference on Heat Transfer. The papers are grouped under the following broad headings: boiling and condensation; heat exchangers; refrigeration and air-conditioning; natural convection; process safety and nuclear reactors; two-phase flow; post dry-out; combustion, radiation and chemical reaction. Separate abstracts have been prepared for 13 papers of relevance to nuclear reactors. (UK)

  16. Feed tank transfer requirements

    Energy Technology Data Exchange (ETDEWEB)

    Freeman-Pollard, J.R.

    1998-09-16

    This document presents a definition of tank turnover. Also, DOE and PC responsibilities; TWRS DST permitting requirements; TWRS Authorization Basis (AB) requirements; TWRS AP Tank Farm operational requirements; unreviewed safety question (USQ) requirements are presented for two cases (i.e., tank modifications occurring before tank turnover and tank modification occurring after tank turnover). Finally, records and reporting requirements, and documentation which will require revision in support of transferring a DST in AP Tank Farm to a privatization contractor are presented.

  17. ATTACHMENT AND TRANSFER

    OpenAIRE

    Pasare, Daniela

    2011-01-01

    Bowlby's concept of attachment and Freud's concept of transference are two of the most influential theories of how we construct mental representations of human relationships. The attachment’s theory offers one more strategy for the therapeutic approach. Factors that lead to a secure attachment between mother and child may also be applied to the relationship between patient and psychotherapist. Psychotherapy may help a patient create himself new attachment and relationship patterns. Creating a...

  18. Technology Transfer Report

    Science.gov (United States)

    2000-01-01

    Since its inception, Goddard has pursued a commitment to technology transfer and commercialization. For every space technology developed, Goddard strives to identify secondary applications. Goddard then provides the technologies, as well as NASA expertise and facilities, to U.S. companies, universities, and government agencies. These efforts are based in Goddard's Technology Commercialization Office. This report presents new technologies, commercialization success stories, and other Technology Commercialization Office activities in 1999.

  19. Chinese Typography Transfer

    OpenAIRE

    Chang, Jie; Gu, Yujun

    2017-01-01

    In this paper, we propose a new network architecture for Chinese typography transformation based on deep learning. The architecture consists of two sub-networks: (1)a fully convolutional network(FCN) aiming at transferring specified typography style to another in condition of preserving structure information; (2)an adversarial network aiming at generating more realistic strokes in some details. Unlike models proposed before 2012 relying on the complex segmentation of Chinese components or str...

  20. Transfer closed and transfer open multimaps in minimal spaces

    International Nuclear Information System (INIS)

    Alimohammady, M.; Roohi, M.; Delavar, M.R.

    2009-01-01

    This paper is devoted to introduce the concepts of transfer closed and transfer open multimaps in minimal spaces. Also, some characterizations of them are considered. Further, the notion of minimal local intersection property will be introduced and characterized. Moreover, some maximal element theorems via minimal transfer closed multimaps and minimal local intersection property are given.