WorldWideScience

Sample records for si image sequences

  1. SI: The Stellar Imager

    Science.gov (United States)

    Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita

    2006-01-01

    The ultra-sharp images of the Stellar Imager (SI) will revolutionize our view of many dynamic astrophysical processes: The 0.1 milliarcsec resolution of this deep-space telescope will transform point sources into extended sources, and simple snapshots into spellbinding evolving views. SI s science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI s prime goal is to enable long-term forecasting of solar activity and the space weather that it drives in support of the Living With a Star program in the Exploration Era by imaging a sample of magnetically active stars with enough resolution to map their evolving dynamo patterns and their internal flows. By exploring the Universe at ultra-high resolution, SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magnetohydrodynamically controlled structures and processes in the Universe.

  2. Region segmentation along image sequence

    International Nuclear Information System (INIS)

    Monchal, L.; Aubry, P.

    1995-01-01

    A method to extract regions in sequence of images is proposed. Regions are not matched from one image to the following one. The result of a region segmentation is used as an initialization to segment the following and image to track the region along the sequence. The image sequence is exploited as a spatio-temporal event. (authors). 12 refs., 8 figs

  3. Image sequence analysis

    CERN Document Server

    1981-01-01

    The processing of image sequences has a broad spectrum of important applica­ tions including target tracking, robot navigation, bandwidth compression of TV conferencing video signals, studying the motion of biological cells using microcinematography, cloud tracking, and highway traffic monitoring. Image sequence processing involves a large amount of data. However, because of the progress in computer, LSI, and VLSI technologies, we have now reached a stage when many useful processing tasks can be done in a reasonable amount of time. As a result, research and development activities in image sequence analysis have recently been growing at a rapid pace. An IEEE Computer Society Workshop on Computer Analysis of Time-Varying Imagery was held in Philadelphia, April 5-6, 1979. A related special issue of the IEEE Transactions on Pattern Anal­ ysis and Machine Intelligence was published in November 1980. The IEEE Com­ puter magazine has also published a special issue on the subject in 1981. The purpose of this book ...

  4. Image registration method for medical image sequences

    Science.gov (United States)

    Gee, Timothy F.; Goddard, James S.

    2013-03-26

    Image registration of low contrast image sequences is provided. In one aspect, a desired region of an image is automatically segmented and only the desired region is registered. Active contours and adaptive thresholding of intensity or edge information may be used to segment the desired regions. A transform function is defined to register the segmented region, and sub-pixel information may be determined using one or more interpolation methods.

  5. The Stellar Imager (SI)"Vision Mission"

    Science.gov (United States)

    Carpenter, Ken; Danchi, W.; Leitner, J.; Liu, A.; Lyon, R.; Mazzuca, L.; Moe, R.; Chenette, D.; Karovska, M.; Allen, R.

    2004-01-01

    The Stellar Imager (SI) is a "Vision" mission in the Sun-Earth Connection (SEC) Roadmap, conceived for the purpose of understanding the effects of stellar magnetic fields, the dynamos that generate them, and the internal structure and dynamics of the stars in which they exist. The ultimate goal is to achieve the best possible forecasting of solar/stellar magnetic activity and its impact on life in the Universe. The science goals of SI require an ultra-high angular resolution, at ultraviolet wavelengths, on the order of 100 micro-arcsec and thus baselines on the order of 0.5 km. These requirements call for a large, multi-spacecraft (less than 20) imaging interferometer, utilizing precision formation flying in a stable environment, such as in a Lissajous orbit around the Sun-Earth L2 point. SI's resolution will make it an invaluable resource for many other areas of astrophysics, including studies of AGN s, supernovae, cataclysmic variables, young stellar objects, QSO's, and stellar black holes. ongoing mission concept and technology development studies for SI. These studies are designed to refine the mission requirements for the science goals, define a Design Reference Mission, perform trade studies of selected major technical and architectural issues, improve the existing technology roadmap, and explore the details of deployment and operations, as well as the possible roles of astronauts and/or robots in construction and servicing of the facility.

  6. The Stellar Imager (SI) Mission Concept

    Science.gov (United States)

    Carpenter, Kenneth G.; Schrijver, Carolus J.; Lyon, Richard G.; Mundy, Lee G.; Allen, Ronald J.; Armstrong, Thomas; Danchi, William C.; Karovska, Margarita; Marzouk, Joe; Mazzuca, Lisa M.; hide

    2002-01-01

    The Stellar Imager (SI) is envisioned as a space-based, UV-optical interferometer composed of 10 or more one-meter class elements distributed with a maximum baseline of 0.5 km. It is designed to image stars and binaries with sufficient resolution to enable long-term studies of stellar magnetic activity patterns, for comparison with those on the sun. It will also support asteroseismology (acoustic imaging) to probe stellar internal structure, differential rotation, and large-scale circulations. SI will enable us to understand the various effects of the magnetic fields of stars, the dynamos that generate these fields, and the internal structure and dynamics of the stars. The ultimate goal of the mission is to achieve the best-possible forecasting of solar activity as a driver of climate and space weather on time scales ranging from months up to decades, and an understanding of the impact of stellar magnetic activity on life in the Universe. In this paper we describe the scientific goals of the mission, the performance requirements needed to address these goals, the "enabling technology" development efforts being pursued, and the design concepts now under study for the full mission and a possible pathfinder mission.

  7. Image correlation method for DNA sequence alignment.

    Science.gov (United States)

    Curilem Saldías, Millaray; Villarroel Sassarini, Felipe; Muñoz Poblete, Carlos; Vargas Vásquez, Asticio; Maureira Butler, Iván

    2012-01-01

    The complexity of searches and the volume of genomic data make sequence alignment one of bioinformatics most active research areas. New alignment approaches have incorporated digital signal processing techniques. Among these, correlation methods are highly sensitive. This paper proposes a novel sequence alignment method based on 2-dimensional images, where each nucleic acid base is represented as a fixed gray intensity pixel. Query and known database sequences are coded to their pixel representation and sequence alignment is handled as object recognition in a scene problem. Query and database become object and scene, respectively. An image correlation process is carried out in order to search for the best match between them. Given that this procedure can be implemented in an optical correlator, the correlation could eventually be accomplished at light speed. This paper shows an initial research stage where results were "digitally" obtained by simulating an optical correlation of DNA sequences represented as images. A total of 303 queries (variable lengths from 50 to 4500 base pairs) and 100 scenes represented by 100 x 100 images each (in total, one million base pair database) were considered for the image correlation analysis. The results showed that correlations reached very high sensitivity (99.01%), specificity (98.99%) and outperformed BLAST when mutation numbers increased. However, digital correlation processes were hundred times slower than BLAST. We are currently starting an initiative to evaluate the correlation speed process of a real experimental optical correlator. By doing this, we expect to fully exploit optical correlation light properties. As the optical correlator works jointly with the computer, digital algorithms should also be optimized. The results presented in this paper are encouraging and support the study of image correlation methods on sequence alignment.

  8. Abdominal MR imaging using a HASTE sequence : image comparison on the different echo times

    International Nuclear Information System (INIS)

    Park, Kwang Bo; Lee, Moon Gyu; Lim, Tae Hwan; Jeong, Yoong Ki; Ha, Hyun Kwon; Kim, Pyo Nyun; Auh, Yong Ho

    1999-01-01

    To determine the optimal parameters of abdominal HASTE imaging by means of a comparison of intermediate and long TE (echo time). We evaluated 30 consecutive patients who had undergone liver MR during a three-month period. Twelve patients were diagnosed as normal, four as having liver cirrhosis, and 14 were found to be suffering form hepatic hemangioma. On the basis of measured signal intensity of the liver, spleen, pancreas and gallbladder, and of fat, muscle, hemangioma, and background, we calculated the ratios of signal to noise (S/N), signal difference to noise (SD/N), and signal intensity (SI). Image quality was compared using these three ratios, and using two HASTE sequences with TEs of 90 msec and 134 msec, images were qualitatively evaluated. S/N ratio of the liver was higher when TE was 90 msec(p<.05), though S/N, SD/N and SI rations of the spleen, gallbladder, and pancreas-and of hemangiom-were higher when TE was 134 msec (p<.05). However, in muscle, all these three ratios were higher at a TE of 90 msec. SD/N ratio and SI of fat were higher at a TE of 134 msec. Overall image quality was better at a TE of 134 msec than at one of 90msec. A HASTE sequence with a TE of 134msec showed greater tissue contrast and stronger T2-weighted images than one with a TE of 90msec

  9. Digital image sequence processing, compression, and analysis

    CERN Document Server

    Reed, Todd R

    2004-01-01

    IntroductionTodd R. ReedCONTENT-BASED IMAGE SEQUENCE REPRESENTATIONPedro M. Q. Aguiar, Radu S. Jasinschi, José M. F. Moura, andCharnchai PluempitiwiriyawejTHE COMPUTATION OF MOTIONChristoph Stiller, Sören Kammel, Jan Horn, and Thao DangMOTION ANALYSIS AND DISPLACEMENT ESTIMATION IN THE FREQUENCY DOMAINLuca Lucchese and Guido Maria CortelazzoQUALITY OF SERVICE ASSESSMENT IN NEW GENERATION WIRELESS VIDEO COMMUNICATIONSGaetano GiuntaERROR CONCEALMENT IN DIGITAL VIDEOFrancesco G.B. De NataleIMAGE SEQUENCE RESTORATION: A WIDER PERSPECTIVEAnil KokaramVIDEO SUMMARIZATIONCuneyt M. Taskiran and Edward

  10. Validated thermodynamic prediction of AlP and eutectic (Si) solidification sequence in Al-Si cast alloys

    International Nuclear Information System (INIS)

    Liang, S M; Schmid-Fetzer, R

    2016-01-01

    The eutectic microstructure in hypoeutectic Al-Si cast alloys is strongly influenced by AlP particles which are potent nuclei for the eutectic (Si) phase. The solidification sequence of AlP and (Si) phases is, thus, crucial for the nucleation of eutectic silicon with marked impact on its morphology. This study presents this interdependence between Si- and P-compositions, relevant for Al-Si cast alloys, on the solidification sequence of AlP and (Si). These data are predicted from a series of thermodynamic calculations. The predictions are based on a self-consistent thermodynamic description of the Al-Si-P ternary alloy system developed recently. They are validated by independent experimental studies on microstructure and undercooling in hypoeutectic Al-Si alloys. A constrained Scheil solidification simulation technique is applied to predict the undercooling under clean heterogeneous nucleation conditions, validated by dedicated experimental observations on entrained droplets. These specific undercooling values may be very large and their quantitative dependence on Si and P content of the Al alloy is presented. (paper)

  11. Realise : reconstruction of reality from image sequences

    NARCIS (Netherlands)

    Leymarie, F.; de la Fortelle, A.; Koenderink, Jan J.; Kappers, A. M L; Stavridi, M.; van Ginneken, B.; Muller, S.; Krake, S.; Faugeras, O.; Robert, L.; Gauclin, C.; Laveau, S.; Zeller, C.; Anon,

    1996-01-01

    REALISE has for principal goals to extract from sequences of images, acquired with a moving camera, information necessary for determining the 3D (CAD-like) structure of a real-life scene together with information about the radiometric signatures of surfaces bounding the extracted 3D objects (e.g.

  12. Statistical processing of large image sequences.

    Science.gov (United States)

    Khellah, F; Fieguth, P; Murray, M J; Allen, M

    2005-01-01

    The dynamic estimation of large-scale stochastic image sequences, as frequently encountered in remote sensing, is important in a variety of scientific applications. However, the size of such images makes conventional dynamic estimation methods, for example, the Kalman and related filters, impractical. In this paper, we present an approach that emulates the Kalman filter, but with considerably reduced computational and storage requirements. Our approach is illustrated in the context of a 512 x 512 image sequence of ocean surface temperature. The static estimation step, the primary contribution here, uses a mixture of stationary models to accurately mimic the effect of a nonstationary prior, simplifying both computational complexity and modeling. Our approach provides an efficient, stable, positive-definite model which is consistent with the given correlation structure. Thus, the methods of this paper may find application in modeling and single-frame estimation.

  13. Surveillance of siRNA integrity by FRET imaging

    Science.gov (United States)

    Järve, Anne; Müller, Julius; Kim, Il-Han; Rohr, Karl; MacLean, Caroline; Fricker, Gert; Massing, Ulrich; Eberle, Florian; Dalpke, Alexander; Fischer, Roger; Trendelenburg, Michael F.; Helm, Mark

    2007-01-01

    Techniques for investigation of exogenous small interfering RNA (siRNA) after penetration of the cell are of substantial interest to the development of efficient transfection methods as well as to potential medical formulations of siRNA. A FRET-based visualization method including the commonplace dye labels fluorescein and tetramethylrhodamin (TMR) on opposing strands of siRNA was found compatible with RNA interference (RNAi). Investigation of spectral properties of three labelled siRNAs with differential FRET efficiencies in the cuvette, including pH dependence and FRET efficiency in lipophilic environments, identified the ratio of red and green fluorescence (R/G-ratio) as a sensitive parameter, which reliably identifies samples containing >90% un-degraded siRNA. Spectral imaging of siRNAs microinjected into cells showed emission spectra indistinguishable from those measured in the cuvette. These were used to establish a calibration curve for assessing the degradation state of siRNA in volume elements inside cells. An algorithm, applied to fluorescence images recorded in standard green and red fluorescence channels, produces R/G-ratio images of high spatial resolution, identifying volume elements in the cell with high populations of intact siRNA with high fidelity. To demonstrate the usefulness of this technique, the movement of intact siRNA molecules are observed after introduction into the cytosol by microinjection, standard transfection and lipofection with liposomes. PMID:17890733

  14. An Imaging And Graphics Workstation For Image Sequence Analysis

    Science.gov (United States)

    Mostafavi, Hassan

    1990-01-01

    This paper describes an application-specific engineering workstation designed and developed to analyze imagery sequences from a variety of sources. The system combines the software and hardware environment of the modern graphic-oriented workstations with the digital image acquisition, processing and display techniques. The objective is to achieve automation and high throughput for many data reduction tasks involving metric studies of image sequences. The applications of such an automated data reduction tool include analysis of the trajectory and attitude of aircraft, missile, stores and other flying objects in various flight regimes including launch and separation as well as regular flight maneuvers. The workstation can also be used in an on-line or off-line mode to study three-dimensional motion of aircraft models in simulated flight conditions such as wind tunnels. The system's key features are: 1) Acquisition and storage of image sequences by digitizing real-time video or frames from a film strip; 2) computer-controlled movie loop playback, slow motion and freeze frame display combined with digital image sharpening, noise reduction, contrast enhancement and interactive image magnification; 3) multiple leading edge tracking in addition to object centroids at up to 60 fields per second from both live input video or a stored image sequence; 4) automatic and manual field-of-view and spatial calibration; 5) image sequence data base generation and management, including the measurement data products; 6) off-line analysis software for trajectory plotting and statistical analysis; 7) model-based estimation and tracking of object attitude angles; and 8) interface to a variety of video players and film transport sub-systems.

  15. Imaging with SiPMs in noble-gas detectors

    International Nuclear Information System (INIS)

    Yahlali, N; González, K; Fernandes, L M P; Garcia, A N C; Soriano, A

    2013-01-01

    Silicon photomultipliers (SiPMs) are photosensors widely used for imaging in a variety of high energy and nuclear physics experiments. In noble-gas detectors for double-beta decay and dark matter experiments, SiPMs are attractive photosensors for imaging. However they are insensitive to the VUV scintillation emitted by the noble gases (xenon and argon). This difficulty is overcome in the NEXT experiment by coating the SiPMs with tetraphenyl butadiene (TPB) to convert the VUV light into visible light. TPB requires stringent storage and operational conditions to prevent its degradation by environmental agents. The development of UV sensitive SiPMs is thus of utmost interest for experiments using electroluminescence of noble-gas detectors. It is in particular an important issue for a robust and background free ββ0ν experiment with xenon gas aimed by NEXT. The photon detection efficiency (PDE) of UV-enhanced SiPMs provided by Hamamatsu was determined for light in the range 250–500 nm. The PDE of standard SiPMs of the same model (S10362-33-50C), coated and non-coated with TPB, was also determined for comparison. In the UV range 250–350 nm, the PDE of the standard SiPM is shown to decrease strongly, down to about 3%. The UV-enhanced SiPM without window is shown to have the maximum PDE of 44% at 325 nm and 30% at 250 nm. The PDE of the UV-enhanced SiPM with silicon resin window has a similar trend in the UV range, although it is about 30% lower. The TPB-coated SiPM has shown to have about 6 times higher PDE than the non-coated SiPM in the range 250–315 nm. This is however below the performance of the UV-enhanced prototypes in the same wavelength range. Imaging in noble-gas detectors using UV-enhanced SiPMs is discussed.

  16. Imaging Si nanoparticles embedded in SiO2 layers by (S)TEM-EELS

    International Nuclear Information System (INIS)

    Schamm, S.; Bonafos, C.; Coffin, H.; Cherkashin, N.; Carrada, M.; Ben Assayag, G.; Claverie, A.; Tence, M.; Colliex, C.

    2008-01-01

    Fabrication of systems in which Si nanoparticles are embedded in a thin silica layer is today mature for non-volatile memory and opto-electronics applications. The control of the different parameters (position, size and density) of the nanoparticles population is a key point to optimize the properties of such systems. A review of dedicated transmission electron microscopy (TEM) methods, which can be used to measure these parameters, is presented with an emphasis on those relying on electron energy-loss spectroscopy (EELS). Defocused bright-field imaging can be used in order to determine topographic information of a whole assembly of nanoparticles, but it is not efficient for looking at individual nanoparticles. High-resolution electron imaging or dark-field imaging can be of help in the case of crystalline particles but they always provide underestimated values of the nanocrystals population. EELS imaging in the low-energy-loss domain around the Si plasmon peak, which gives rise to strong signals, is the only way to visualize all Si nanoparticles within a silica film and to perform reliable size and density measurements. Two complementary types of experiments are investigated and discussed more extensively: direct imaging with a transmission electron microscope equipped with an imaging filter (EFTEM) and indirect imaging from spectrum-imaging data acquired with a scanning transmission electron microscope equipped with a spectrometer (STEM-PEELS). The direct image (EFTEM) and indirect set of spectra (STEM-PEELS) are processed in order to deliver images where the contribution of the silica matrix is minimized. The contrast of the resulting images can be enhanced with adapted numerical filters for further morphometric analysis. The two methods give equivalent results, with an easier access for EFTEM and the possibility of a more detailed study of the EELS signatures in the case of STEM-PEELS. Irradiation damage in such systems is also discussed

  17. Molecular beam epitaxy grown Ge/Si pin layer sequence for photonic devices

    International Nuclear Information System (INIS)

    Schulze, J.; Oehme, M.; Werner, J.

    2012-01-01

    A key challenge to obtain a convergence of classical Si-based microelectronics and optoelectronics is the manufacturing of photonic integrated circuits integrable into classical Si-based integrated circuits. This integration would be greatly enhanced if similar facilities and technologies could be used. Therefore one approach is the development of optoelectronic components and devices made from group-IV-based materials such as SiGe, Ge or Ge:Sn. In this paper the optoelectronic performances of a pin diode made from a Ge/Si heterostructure pin layer sequence grown by molecular beam epitaxy are discussed. After a detailed description of the layer sequence growth and the device manufacturing process it will be shown that – depending on the chosen operating point and device design – the diode serves as a broadband high speed photo detector, Franz–Keldysh effect modulator or light emitting diode.

  18. Molecular beam epitaxy grown Ge/Si pin layer sequence for photonic devices

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, J., E-mail: schulze@iht.uni-stuttgart.de; Oehme, M.; Werner, J.

    2012-02-01

    A key challenge to obtain a convergence of classical Si-based microelectronics and optoelectronics is the manufacturing of photonic integrated circuits integrable into classical Si-based integrated circuits. This integration would be greatly enhanced if similar facilities and technologies could be used. Therefore one approach is the development of optoelectronic components and devices made from group-IV-based materials such as SiGe, Ge or Ge:Sn. In this paper the optoelectronic performances of a pin diode made from a Ge/Si heterostructure pin layer sequence grown by molecular beam epitaxy are discussed. After a detailed description of the layer sequence growth and the device manufacturing process it will be shown that - depending on the chosen operating point and device design - the diode serves as a broadband high speed photo detector, Franz-Keldysh effect modulator or light emitting diode.

  19. Eigenimage filtering of nuclear medicine image sequences

    International Nuclear Information System (INIS)

    Windham, J.P.; Froelich, J.W.; Abd-Allah, M.

    1985-01-01

    In many nuclear medicine imaging sequences the localization of radioactivity in organs other than the target organ interferes with imaging of the desired anatomical structure or physiological process. A filtering technique has been developed which suppresses the interfering process while enhancing the desired process. This technique requires the identification of temporal sequential signatures for both the interfering and desired processes. These signatures are placed in the form of signature vectors. Signature matrices, M/sub D/ and M/sub U/, are formed by taking the outer product expansion of the temporal signature vectors for the desired and interfering processes respectively. By using the transformation from the simultaneous diagonalization of these two signature matrices a weighting vector is obtained. The technique is shown to maximize the projection of the desired process while minimizing the interfering process based upon an extension of Rayleigh's Principle. The technique is demonstrated for first pass renal and cardiac flow studies. This filter offers a potential for simplifying and extending the accuracy of diagnostic nuclear medicine procedures

  20. Ultra-fast sequence clustering from similarity networks with SiLiX

    Directory of Open Access Journals (Sweden)

    Duret Laurent

    2011-04-01

    Full Text Available Abstract Background The number of gene sequences that are available for comparative genomics approaches is increasing extremely quickly. A current challenge is to be able to handle this huge amount of sequences in order to build families of homologous sequences in a reasonable time. Results We present the software package SiLiX that implements a novel method which reconsiders single linkage clustering with a graph theoretical approach. A parallel version of the algorithms is also presented. As a demonstration of the ability of our software, we clustered more than 3 millions sequences from about 2 billion BLAST hits in 7 minutes, with a high clustering quality, both in terms of sensitivity and specificity. Conclusions Comparing state-of-the-art software, SiLiX presents the best up-to-date capabilities to face the problem of clustering large collections of sequences. SiLiX is freely available at http://lbbe.univ-lyon1.fr/SiLiX.

  1. Pulse sequences for contrast-enhanced magnetic resonance imaging

    International Nuclear Information System (INIS)

    Graves, Martin J.

    2007-01-01

    The theory and application of magnetic resonance imaging (MRI) pulse sequences following the administration of an exogenous contrast agent are discussed. Pulse sequences are categorised according to the contrast agent mechanism: changes in proton density, relaxivity, magnetic susceptibility and resonant frequency shift. Applications in morphological imaging, magnetic resonance angiography, dynamic imaging and cell labelling are described. The importance of optimising the pulse sequence for each application is emphasised

  2. Deep Sequencing Insights in Therapeutic shRNA Processing and siRNA Target Cleavage Precision.

    Science.gov (United States)

    Denise, Hubert; Moschos, Sterghios A; Sidders, Benjamin; Burden, Frances; Perkins, Hannah; Carter, Nikki; Stroud, Tim; Kennedy, Michael; Fancy, Sally-Ann; Lapthorn, Cris; Lavender, Helen; Kinloch, Ross; Suhy, David; Corbau, Romu

    2014-02-04

    TT-034 (PF-05095808) is a recombinant adeno-associated virus serotype 8 (AAV8) agent expressing three short hairpin RNA (shRNA) pro-drugs that target the hepatitis C virus (HCV) RNA genome. The cytosolic enzyme Dicer cleaves each shRNA into multiple, potentially active small interfering RNA (siRNA) drugs. Using next-generation sequencing (NGS) to identify and characterize active shRNAs maturation products, we observed that each TT-034-encoded shRNA could be processed into as many as 95 separate siRNA strands. Few of these appeared active as determined by Sanger 5' RNA Ligase-Mediated Rapid Amplification of cDNA Ends (5-RACE) and through synthetic shRNA and siRNA analogue studies. Moreover, NGS scrutiny applied on 5-RACE products (RACE-seq) suggested that synthetic siRNAs could direct cleavage in not one, but up to five separate positions on targeted RNA, in a sequence-dependent manner. These data support an on-target mechanism of action for TT-034 without cytotoxicity and question the accepted precision of substrate processing by the key RNA interference (RNAi) enzymes Dicer and siRNA-induced silencing complex (siRISC).Molecular Therapy-Nucleic Acids (2014) 3, e145; doi:10.1038/mtna.2013.73; published online 4 February 2014.

  3. Direct Imaging of Stellar Surfaces: Results from the Stellar Imager (SI) Vision Mission Study

    Science.gov (United States)

    Carpenter, Kenneth; Schrijver, Carolus; Karovska, Margarita

    2006-01-01

    The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and stellar interiors (via asteroseismology) and of the Universe in general. SI is identified as a "Flagship and Landmark Discovery Mission'' in the 2005 Sun Solar System Connection (SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory'' in the Exploration of the Universe Division (EUD) Roadmap (May, 2005). The ultra-sharp images of the Stellar Imager will revolutionize our view of many dynamic astrophysical processes: The 0.1 mas resolution of this deep-space telescope will transform point sources into extended sources, and snapshots into evolving views. SI's science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI's prime goal is to enable long-term forecasting of solar activity and the space weather that it drives in support of the Living With a Star program in the Exploration Era. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. In this paper we will discuss the results of the SI Vision Mission Study, elaborating on the science goals of the SI Mission and a mission architecture that could meet those goals.

  4. Efficient construction of an inverted minimal H1 promoter driven siRNA expression cassette: facilitation of promoter and siRNA sequence exchange.

    Directory of Open Access Journals (Sweden)

    Hoorig Nassanian

    2007-08-01

    Full Text Available RNA interference (RNAi, mediated by small interfering RNA (siRNA, is an effective method used to silence gene expression at the post-transcriptional level. Upon introduction into target cells, siRNAs incorporate into the RNA-induced silencing complex (RISC. The antisense strand of the siRNA duplex then "guides" the RISC to the homologous mRNA, leading to target degradation and gene silencing. In recent years, various vector-based siRNA expression systems have been developed which utilize opposing polymerase III promoters to independently drive expression of the sense and antisense strands of the siRNA duplex from the same template.We show here the use of a ligase chain reaction (LCR to develop a new vector system called pInv-H1 in which a DNA sequence encoding a specific siRNA is placed between two inverted minimal human H1 promoters (approximately 100 bp each. Expression of functional siRNAs from this construct has led to efficient silencing of both reporter and endogenous genes. Furthermore, the inverted H1 promoter-siRNA expression cassette was used to generate a retrovirus vector capable of transducing and silencing expression of the targeted protein by>80% in target cells.The unique design of this construct allows for the efficient exchange of siRNA sequences by the directional cloning of short oligonucleotides via asymmetric restriction sites. This provides a convenient way to test the functionality of different siRNA sequences. Delivery of the siRNA cassette by retroviral transduction suggests that a single copy of the siRNA expression cassette efficiently knocks down gene expression at the protein level. We note that this vector system can potentially be used to generate a random siRNA library. The flexibility of the ligase chain reaction suggests that additional control elements can easily be introduced into this siRNA expression cassette.

  5. A New Images Hiding Scheme Based on Chaotic Sequences

    Institute of Scientific and Technical Information of China (English)

    LIU Nian-sheng; GUO Dong-hui; WU Bo-xi; Parr G

    2005-01-01

    We propose a data hidding technique in a still image. This technique is based on chaotic sequence in the transform domain of covert image. We use different chaotic random sequences multiplied by multiple sensitive images, respectively, to spread the spectrum of sensitive images. Multiple sensitive images are hidden in a covert image as a form of noise. The results of theoretical analysis and computer simulation show the new hiding technique have better properties with high security, imperceptibility and capacity for hidden information in comparison with the conventional scheme such as LSB (Least Significance Bit).

  6. Direct UV/Optical Imaging of Stellar Surfaces: The Stellar Imager (SI) Vision Mission

    Science.gov (United States)

    Carpenter, Kenneth G.; Lyon, Richard G.; Schrijver, Carolus; Karovska, Margarita; Mozurkewich, David

    2007-01-01

    The Stellar Imager (SI) is a UV/optical, space-based interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and, via asteroseismology, stellar interiors and of the Universe in general. SI's science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI's prime goal is to enable long-term forecasting of solar activity and the space weather that it drives, in support of the Living with a Star program in the Exploration Era. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in thc Universe. SI is a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System Connection (SSSC) Roadmap and a candidate for a "Pathways to Life Observatory" in the Exploration of the Universe Division (EUD) Roadmap. We discuss herein the science goals of the SI Mission, a mission architecture that could meet those goals, and the technologies needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/.

  7. Enhancing potency of siRNA targeting fusion genes by optimization outside of target sequence.

    Science.gov (United States)

    Gavrilov, Kseniya; Seo, Young-Eun; Tietjen, Gregory T; Cui, Jiajia; Cheng, Christopher J; Saltzman, W Mark

    2015-12-01

    Canonical siRNA design algorithms have become remarkably effective at predicting favorable binding regions within a target mRNA, but in some cases (e.g., a fusion junction site) region choice is restricted. In these instances, alternative approaches are necessary to obtain a highly potent silencing molecule. Here we focus on strategies for rational optimization of two siRNAs that target the junction sites of fusion oncogenes BCR-ABL and TMPRSS2-ERG. We demonstrate that modifying the termini of these siRNAs with a terminal G-U wobble pair or a carefully selected pair of terminal asymmetry-enhancing mismatches can result in an increase in potency at low doses. Importantly, we observed that improvements in silencing at the mRNA level do not necessarily translate to reductions in protein level and/or cell death. Decline in protein level is also heavily influenced by targeted protein half-life, and delivery vehicle toxicity can confound measures of cell death due to silencing. Therefore, for BCR-ABL, which has a long protein half-life that is difficult to overcome using siRNA, we also developed a nontoxic transfection vector: poly(lactic-coglycolic acid) nanoparticles that release siRNA over many days. We show that this system can achieve effective killing of leukemic cells. These findings provide insights into the implications of siRNA sequence for potency and suggest strategies for the design of more effective therapeutic siRNA molecules. Furthermore, this work points to the importance of integrating studies of siRNA design and delivery, while heeding and addressing potential limitations such as restricted targetable mRNA regions, long protein half-lives, and nonspecific toxicities.

  8. Safety Assessment of Advanced Imaging Sequences I: Measurements

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Rasmussen, Morten Fischer; Pihl, Michael Johannes

    2016-01-01

    intensity measurement program. The approach can measure and store data for a full imaging sequence in 3.8 to 8.2 s per spatial position. Based on Ispta, MI, and probe surface temperature, the method gives the ability to determine whether a sequence is within US FDA limits, or alternatively indicate how......A method for rapid measurement of intensities (Ispta), mechanical index (MI), and probe surface temperature for any ultrasound scanning sequence is presented. It uses the scanner’s sampling capability to give an accurate measurement of the whole imaging sequence for all emissions to yield the true...... measurement system (Onda Corporation, Sunnyvale, CA, USA). Four different sequences have been measured: a fixed focus emission, a duplex sequence containing B-mode and flow emissions, a vector flow sequence with B-mode and flow emissions in 17 directions, and finally a synthetic aperture (SA) duplex flow...

  9. Sequence of phase transitions in (NH4)3SiF7.

    Science.gov (United States)

    Mel'nikova, S V; Molokeev, M S; Laptash, N M; Pogoreltsev, E I; Misyul, S V; Flerov, I N

    2017-02-21

    Single crystals of silicon double salt (NH 4 ) 3 SiF 7 = (NH 4 ) 2 SiF 6 ·NH 4 F = (NH 4 ) 3 [SiF 6 ]F were grown and studied by the methods of polarization optics, X-ray diffraction and calorimetry. A sequence of symmetry transformations with the temperature change was established: P4/mbm (Z = 2) (G 1 ) ↔ Pbam (Z = 4) (G 2 ) ↔ P2 1 /c (Z = 4) (G 3 ) ↔ P1[combining macron] (Z = 4) (G 4 ) ↔ P2 1 /c (Z = 8) (G 5 ). Crystal structures of different phases were determined. The experimental data were also interpreted by a group-theoretical analysis of the complete condensate of order parameters taking into account critical and noncritical atomic displacements. Strengthening of the N-HF hydrogen bonds can be a driving force of the observed phase transitions.

  10. Spatio-temporal alignment of pedobarographic image sequences.

    Science.gov (United States)

    Oliveira, Francisco P M; Sousa, Andreia; Santos, Rubim; Tavares, João Manuel R S

    2011-07-01

    This article presents a methodology to align plantar pressure image sequences simultaneously in time and space. The spatial position and orientation of a foot in a sequence are changed to match the foot represented in a second sequence. Simultaneously with the spatial alignment, the temporal scale of the first sequence is transformed with the aim of synchronizing the two input footsteps. Consequently, the spatial correspondence of the foot regions along the sequences as well as the temporal synchronizing is automatically attained, making the study easier and more straightforward. In terms of spatial alignment, the methodology can use one of four possible geometric transformation models: rigid, similarity, affine, or projective. In the temporal alignment, a polynomial transformation up to the 4th degree can be adopted in order to model linear and curved time behaviors. Suitable geometric and temporal transformations are found by minimizing the mean squared error (MSE) between the input sequences. The methodology was tested on a set of real image sequences acquired from a common pedobarographic device. When used in experimental cases generated by applying geometric and temporal control transformations, the methodology revealed high accuracy. In addition, the intra-subject alignment tests from real plantar pressure image sequences showed that the curved temporal models produced better MSE results (P alignment of pedobarographic image data, since previous methods can only be applied on static images.

  11. Motion Detection in Ultrasound Image-Sequences Using Tensor Voting

    Science.gov (United States)

    Inba, Masafumi; Yanagida, Hirotaka; Tamura, Yasutaka

    2008-05-01

    Motion detection in ultrasound image sequences using tensor voting is described. We have been developing an ultrasound imaging system adopting a combination of coded excitation and synthetic aperture focusing techniques. In our method, frame rate of the system at distance of 150 mm reaches 5000 frame/s. Sparse array and short duration coded ultrasound signals are used for high-speed data acquisition. However, many artifacts appear in the reconstructed image sequences because of the incompleteness of the transmitted code. To reduce the artifacts, we have examined the application of tensor voting to the imaging method which adopts both coded excitation and synthetic aperture techniques. In this study, the basis of applying tensor voting and the motion detection method to ultrasound images is derived. It was confirmed that velocity detection and feature enhancement are possible using tensor voting in the time and space of simulated ultrasound three-dimensional image sequences.

  12. Fat suppression in MR imaging with binomial pulse sequences

    International Nuclear Information System (INIS)

    Baudovin, C.J.; Bryant, D.J.; Bydder, G.M.; Young, I.R.

    1989-01-01

    This paper reports on a study to develop pulse sequences allowing suppression of fat signal on MR images without eliminating signal from other tissues with short T1. They have developed such a technique involving selective excitation of protons in water, based on a binomial pulse sequence. Imaging is performed at 0.15 T. Careful shimming is performed to maximize separation of fat and water peaks. A spin-echo 1,500/80 sequence is used, employing 90 degrees pulse with transit frequency optimized for water with null excitation of 20 H offset, followed by a section-selective 180 degrees pulse. With use of the binomial sequence for imagining, reduction in fat signal is seen on images of the pelvis and legs of volunteers. Patient studies show dramatic improvement in visualization of prostatic carcinoma compared with standard sequences

  13. Image encryption using random sequence generated from generalized information domain

    International Nuclear Information System (INIS)

    Zhang Xia-Yan; Wu Jie-Hua; Zhang Guo-Ji; Li Xuan; Ren Ya-Zhou

    2016-01-01

    A novel image encryption method based on the random sequence generated from the generalized information domain and permutation–diffusion architecture is proposed. The random sequence is generated by reconstruction from the generalized information file and discrete trajectory extraction from the data stream. The trajectory address sequence is used to generate a P-box to shuffle the plain image while random sequences are treated as keystreams. A new factor called drift factor is employed to accelerate and enhance the performance of the random sequence generator. An initial value is introduced to make the encryption method an approximately one-time pad. Experimental results show that the random sequences pass the NIST statistical test with a high ratio and extensive analysis demonstrates that the new encryption scheme has superior security. (paper)

  14. Image ranking in video sequences using pairwise image comparisons and temporal smoothing

    CSIR Research Space (South Africa)

    Burke, Michael

    2016-12-01

    Full Text Available The ability to predict the importance of an image is highly desirable in computer vision. This work introduces an image ranking scheme suitable for use in video or image sequences. Pairwise image comparisons are used to determine image ‘interest...

  15. Analysis on the sequence of formation of Ti{sub 3}SiC{sub 2} and Ti{sub 3}SiC{sub 2}/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Radhakrishnan, R.; Bhaduri, S.B. [Idaho Univ., Moscow, ID (United States). Dept. of Mining and Metallurgy; Henager, C.H. Jr. [Pacific Northwest Lab., Richland, WA (United States)

    1995-05-01

    Ti{sub 3}SiC{sub 2}, a compound in the ternary Ti-Si-C system, is reported to be ductile. This paper reports the sequence of formation of Ti{sub 3}SiC{sub 2} and Ti{sub 3}SiC{sub 2}/SiC composites involving either combustion synthesis or by displacement reaction, respectively. Onset of exothermic reaction temperatures were determined using Differential Thermal Analysis (DTA). Phases present after the exothermic temperatures were analyzed by X-Ray diffraction. Based on these observations, a route to formation of Ti{sub 3}SiC{sub 2} and Ti{sub 3}SiC{sub 2}/SiC composites is proposed for the two`s thesis methods.

  16. New diffusion imaging method with a single acquisition sequence

    International Nuclear Information System (INIS)

    Melki, Ph.S.; Bittoun, J.; Lefevre, J.E.

    1987-01-01

    The apparent diffusion coefficient (ADC) is related to the molecular diffusion coefficient and to physiologic information: microcirculation in the capillary network, incoherent slow flow, and restricted diffusion. The authors present a new MR imaging sequence that yields computed ADC images in only one acquisition of 9-minutes with a 1.5-T imager (GE Signa). Compared to the previous method, this sequence is at least two times faster and thus can be used as a routine examination to supplement T1-, T2-, and density-weighted images. The method was assessed by measurement of the molecular diffusion in liquids, and the first clinical images obtained in neurologic diseases demonstrate its efficiency for clinical investigation. The possibility of separately imaging diffusion and perfusion is supported by an algorithm

  17. Image sequence analysis workstation for multipoint motion analysis

    Science.gov (United States)

    Mostafavi, Hassan

    1990-08-01

    This paper describes an application-specific engineering workstation designed and developed to analyze motion of objects from video sequences. The system combines the software and hardware environment of a modem graphic-oriented workstation with the digital image acquisition, processing and display techniques. In addition to automation and Increase In throughput of data reduction tasks, the objective of the system Is to provide less invasive methods of measurement by offering the ability to track objects that are more complex than reflective markers. Grey level Image processing and spatial/temporal adaptation of the processing parameters is used for location and tracking of more complex features of objects under uncontrolled lighting and background conditions. The applications of such an automated and noninvasive measurement tool include analysis of the trajectory and attitude of rigid bodies such as human limbs, robots, aircraft in flight, etc. The system's key features are: 1) Acquisition and storage of Image sequences by digitizing and storing real-time video; 2) computer-controlled movie loop playback, freeze frame display, and digital Image enhancement; 3) multiple leading edge tracking in addition to object centroids at up to 60 fields per second from both live input video or a stored Image sequence; 4) model-based estimation and tracking of the six degrees of freedom of a rigid body: 5) field-of-view and spatial calibration: 6) Image sequence and measurement data base management; and 7) offline analysis software for trajectory plotting and statistical analysis.

  18. Extracting flat-field images from scene-based image sequences using phase correlation

    Energy Technology Data Exchange (ETDEWEB)

    Caron, James N., E-mail: Caron@RSImd.com [Research Support Instruments, 4325-B Forbes Boulevard, Lanham, Maryland 20706 (United States); Montes, Marcos J. [Naval Research Laboratory, Code 7231, 4555 Overlook Avenue, SW, Washington, DC 20375 (United States); Obermark, Jerome L. [Naval Research Laboratory, Code 8231, 4555 Overlook Avenue, SW, Washington, DC 20375 (United States)

    2016-06-15

    Flat-field image processing is an essential step in producing high-quality and radiometrically calibrated images. Flat-fielding corrects for variations in the gain of focal plane array electronics and unequal illumination from the system optics. Typically, a flat-field image is captured by imaging a radiometrically uniform surface. The flat-field image is normalized and removed from the images. There are circumstances, such as with remote sensing, where a flat-field image cannot be acquired in this manner. For these cases, we developed a phase-correlation method that allows the extraction of an effective flat-field image from a sequence of scene-based displaced images. The method uses sub-pixel phase correlation image registration to align the sequence to estimate the static scene. The scene is removed from sequence producing a sequence of misaligned flat-field images. An average flat-field image is derived from the realigned flat-field sequence.

  19. MISTICA: Minimum Spanning Tree-Based Coarse Image Alignment for Microscopy Image Sequences.

    Science.gov (United States)

    Ray, Nilanjan; McArdle, Sara; Ley, Klaus; Acton, Scott T

    2016-11-01

    Registration of an in vivo microscopy image sequence is necessary in many significant studies, including studies of atherosclerosis in large arteries and the heart. Significant cardiac and respiratory motion of the living subject, occasional spells of focal plane changes, drift in the field of view, and long image sequences are the principal roadblocks. The first step in such a registration process is the removal of translational and rotational motion. Next, a deformable registration can be performed. The focus of our study here is to remove the translation and/or rigid body motion that we refer to here as coarse alignment. The existing techniques for coarse alignment are unable to accommodate long sequences often consisting of periods of poor quality images (as quantified by a suitable perceptual measure). Many existing methods require the user to select an anchor image to which other images are registered. We propose a novel method for coarse image sequence alignment based on minimum weighted spanning trees (MISTICA) that overcomes these difficulties. The principal idea behind MISTICA is to reorder the images in shorter sequences, to demote nonconforming or poor quality images in the registration process, and to mitigate the error propagation. The anchor image is selected automatically making MISTICA completely automated. MISTICA is computationally efficient. It has a single tuning parameter that determines graph width, which can also be eliminated by the way of additional computation. MISTICA outperforms existing alignment methods when applied to microscopy image sequences of mouse arteries.

  20. Post-contrast T1-weighted sequences in pediatric abdominal imaging: comparative analysis of three different sequences and imaging approach

    Energy Technology Data Exchange (ETDEWEB)

    Roque, Andreia; Ramalho, Miguel; AlObaidy, Mamdoh; Heredia, Vasco; Burke, Lauren M.; De Campos, Rafael O.P.; Semelka, Richard C. [University of North Carolina at Chapel Hill, Department of Radiology, Chapel Hill, NC (United States)

    2014-10-15

    Post-contrast T1-weighted imaging is an essential component of a comprehensive pediatric abdominopelvic MR examination. However, consistent good image quality is challenging, as respiratory motion in sedated children can substantially degrade the image quality. To compare the image quality of three different post-contrast T1-weighted imaging techniques - standard three-dimensional gradient-echo (3-D-GRE), magnetization-prepared gradient-recall echo (MP-GRE) and 3-D-GRE with radial data sampling (radial 3-D-GRE) - acquired in pediatric patients younger than 5 years of age. Sixty consecutive exams performed in 51 patients (23 females, 28 males; mean age 2.5 ± 1.4 years) constituted the final study population. Thirty-nine scans were performed at 3 T and 21 scans were performed at 1.5 T. Two different reviewers independently and blindly qualitatively evaluated all sequences to determine image quality and extent of artifacts. MP-GRE and radial 3-D-GRE sequences had the least respiratory motion (P < 0.0001). Standard 3-D-GRE sequences displayed the lowest average score ratings in hepatic and pancreatic edge definition, hepatic vessel clarity and overall image quality. Radial 3-D-GRE sequences showed the highest scores ratings in overall image quality. Our preliminary results support the preference of fat-suppressed radial 3-D-GRE as the best post-contrast T1-weighted imaging approach for patients under the age of 5 years, when dynamic imaging is not essential. (orig.)

  1. Geometrical primitives reconstruction from image sequence in an interactive context

    International Nuclear Information System (INIS)

    Monchal, L.; Aubry, P.

    1995-01-01

    We propose a method to recover 3D geometrical shape from image sequence, in a context of man machine co-operation. The human operator has to point out the edges of an object in the first image and choose a corresponding geometrical model. The algorithm tracks each relevant 2D segments describing surface discontinuities or limbs, in the images. Then, knowing motion of the camera between images, the positioning and the size of the virtual object are deduced by minimising a function. The function describes how well the virtual objects is linked to the extracted segments of the sequence, its geometrical model and pieces of information given by the operator. (author). 13 refs., 7 figs., 8 tabs

  2. MR imaging pulse sequence rationale: SD-, T1-, and T2-weighted images

    International Nuclear Information System (INIS)

    Sax, S.; Weathers, S.W.; Schneiders, N.J.; Horowitz, B.L.; Mawad, M.E.; Sandlin, M.E.; Blackwell, R.; Bryan, R.N.

    1986-01-01

    Over 500 patients have been examined with a pulse sequence designed to provide spin-density (SD)-weighted images (TR=3 sec, TE=35 msec), T1-weighted images (TR=0.3 sec, TE=35msec), and T2-weighted images (TR=3 sec, TE=105 msec) from which calculated ''synthesized'' images and SD, T1, and T2 calculated images could be obtained. Each image contributes unique information. SD-weighted images optimally display anatomy and often best highlight pathology. T1-weighted images are critical in assessing cerebral hemorrhages. T2-weighted images best display most lesions, but yield incomplete information in 35% of cases. All three types of ''weighted'' images are necessary to optimally display anatomy and fully characterize a lesion. Computerized calculations and simulations suggest that no other combination of pulse sequences yields equal information for a given examination time

  3. Research on hyperspectral dynamic scene and image sequence simulation

    Science.gov (United States)

    Sun, Dandan; Liu, Fang; Gao, Jiaobo; Sun, Kefeng; Hu, Yu; Li, Yu; Xie, Junhu; Zhang, Lei

    2016-10-01

    This paper presents a simulation method of hyperspectral dynamic scene and image sequence for hyperspectral equipment evaluation and target detection algorithm. Because of high spectral resolution, strong band continuity, anti-interference and other advantages, in recent years, hyperspectral imaging technology has been rapidly developed and is widely used in many areas such as optoelectronic target detection, military defense and remote sensing systems. Digital imaging simulation, as a crucial part of hardware in loop simulation, can be applied to testing and evaluation hyperspectral imaging equipment with lower development cost and shorter development period. Meanwhile, visual simulation can produce a lot of original image data under various conditions for hyperspectral image feature extraction and classification algorithm. Based on radiation physic model and material characteristic parameters this paper proposes a generation method of digital scene. By building multiple sensor models under different bands and different bandwidths, hyperspectral scenes in visible, MWIR, LWIR band, with spectral resolution 0.01μm, 0.05μm and 0.1μm have been simulated in this paper. The final dynamic scenes have high real-time and realistic, with frequency up to 100 HZ. By means of saving all the scene gray data in the same viewpoint image sequence is obtained. The analysis results show whether in the infrared band or the visible band, the grayscale variations of simulated hyperspectral images are consistent with the theoretical analysis results.

  4. Simulation and Efficient Measurements of Intensities for Complex Imaging Sequences

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Rasmussen, Morten Fischer; Stuart, Matthias Bo

    2014-01-01

    on the sequence to simulate both intensity and mechanical index (MI) according to FDA rules. A 3 MHz BK Medical 8820e convex array transducer is used with the SARUS scanner. An Onda HFL-0400 hydrophone and the Onda AIMS III system measures the pressure field for three imaging schemes: a fixed focus, single...

  5. How to Tackle the Challenge of siRNA Delivery with Sequence-Defined Oligoamino Amides.

    Science.gov (United States)

    Reinhard, Sören; Wagner, Ernst

    2017-01-01

    RNA interference (RNAi) as a mechanism of gene regulation provides exciting opportunities for medical applications. Synthetic small interfering RNA (siRNA) triggers the knockdown of complementary mRNA sequences in a catalytic fashion and has to be delivered into the cytosol of the targeted cells. The design of adequate carrier systems to overcome multiple extracellular and intracellular roadblocks within the delivery process has utmost importance. Cationic polymers form polyplexes through electrostatic interaction with negatively charged nucleic acids and present a promising class of carriers. Issues of polycations regarding toxicity, heterogeneity, and polydispersity can be overcome by solid-phase-assisted synthesis of sequence-defined cationic oligomers. These medium-sized highly versatile nucleic acid carriers display low cytotoxicity and can be modified and tailored in multiple ways to meet specific requirements of nucleic acid binding, polyplex size, shielding, targeting, and intracellular release of the cargo. In this way, sequence-defined cationic oligomers can mimic the dynamic and bioresponsive behavior of viruses. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Optical flow estimation on image sequences with differently exposed frames

    Science.gov (United States)

    Bengtsson, Tomas; McKelvey, Tomas; Lindström, Konstantin

    2015-09-01

    Optical flow (OF) methods are used to estimate dense motion information between consecutive frames in image sequences. In addition to the specific OF estimation method itself, the quality of the input image sequence is of crucial importance to the quality of the resulting flow estimates. For instance, lack of texture in image frames caused by saturation of the camera sensor during exposure can significantly deteriorate the performance. An approach to avoid this negative effect is to use different camera settings when capturing the individual frames. We provide a framework for OF estimation on such sequences that contain differently exposed frames. Information from multiple frames are combined into a total cost functional such that the lack of an active data term for saturated image areas is avoided. Experimental results demonstrate that using alternate camera settings to capture the full dynamic range of an underlying scene can clearly improve the quality of flow estimates. When saturation of image data is significant, the proposed methods show superior performance in terms of lower endpoint errors of the flow vectors compared to a set of baseline methods. Furthermore, we provide some qualitative examples of how and when our method should be used.

  7. Studying a free fall experiment using short sequences of images

    International Nuclear Information System (INIS)

    Vera, Francisco; Romanque, Cristian

    2008-01-01

    We discuss a new alternative for obtaining position and time coordinates from a video of a free fall experiment. In our approach, after converting the video to a short sequence of images, the images are analyzed using a web page application developed by the author. The main advantage of the setup explained in this work, is that it is simple to use, no software license fees are necessary, and can be scaled-up to be used by a big number of students in introductory physics courses. The steps involved in the full analysis of a falling object are: we grab a short digital video of the experiment and convert it to a sequence of images, then, using a web page that includes all the necessary javascript, the student can easily click on the object of interest to obtain the (x,y,t) coordinates, finally, the student analyze motion using a spreadsheet.

  8. Extended -Regular Sequence for Automated Analysis of Microarray Images

    Directory of Open Access Journals (Sweden)

    Jin Hee-Jeong

    2006-01-01

    Full Text Available Microarray study enables us to obtain hundreds of thousands of expressions of genes or genotypes at once, and it is an indispensable technology for genome research. The first step is the analysis of scanned microarray images. This is the most important procedure for obtaining biologically reliable data. Currently most microarray image processing systems require burdensome manual block/spot indexing work. Since the amount of experimental data is increasing very quickly, automated microarray image analysis software becomes important. In this paper, we propose two automated methods for analyzing microarray images. First, we propose the extended -regular sequence to index blocks and spots, which enables a novel automatic gridding procedure. Second, we provide a methodology, hierarchical metagrid alignment, to allow reliable and efficient batch processing for a set of microarray images. Experimental results show that the proposed methods are more reliable and convenient than the commercial tools.

  9. Hyperpolarized Porous Silicon Nanoparticles: Potential Theragnostic Material for ²⁹Si Magnetic Resonance Imaging.

    Science.gov (United States)

    Seo, Hyeonglim; Choi, Ikjang; Whiting, Nicholas; Hu, Jingzhe; Luu, Quy Son; Pudakalakatti, Shivanand; McCowan, Caitlin; Kim, Yaewon; Zacharias, Niki; Lee, Seunghyun; Bhattacharya, Pratip; Lee, Youngbok

    2018-05-20

    Porous silicon nanoparticles have recently garnered attention as potentially-promising biomedical platforms for drug delivery and medical diagnostics. Here, we demonstrate porous silicon nanoparticles as contrast agents for ²⁹Si magnetic resonance imaging. Size-controlled porous silicon nanoparticles were synthesized by magnesiothermic reduction of silica nanoparticles and were surface activated for further functionalization. Particles were hyperpolarized via dynamic nuclear polarization to enhance their ²⁹Si MR signals; the particles demonstrated long ²⁹Si spin-lattice relaxation (T₁) times (~ 25 mins), which suggests potential applicability for medical imaging. Furthermore, ²⁹Si hyperpolarization levels were sufficient to allow ²⁹Si MRI in phantoms. These results underscore the potential of porous silicon nanoparticles that, when combined with hyperpolarized magnetic resonance imaging, can be a powerful theragnostic deep tissue imaging platform to interrogate various biomolecular processes in vivo. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Image sequence analysis in nuclear medicine: (1) Parametric imaging using statistical modelling

    International Nuclear Information System (INIS)

    Liehn, J.C.; Hannequin, P.; Valeyre, J.

    1989-01-01

    This is a review of parametric imaging methods on Nuclear Medicine. A Parametric Image is an image in which each pixel value is a function of the value of the same pixel of an image sequence. The Local Model Method is the fitting of each pixel time activity curve by a model which parameter values form the Parametric Images. The Global Model Method is the modelling of the changes between two images. It is applied to image comparison. For both methods, the different models, the identification criterion, the optimization methods and the statistical properties of the images are discussed. The analysis of one or more Parametric Images is performed using 1D or 2D histograms. The statistically significant Parametric Images, (Images of significant Variances, Amplitudes and Differences) are also proposed [fr

  11. Minimum TE gradient-recalled phosphorus imaging sequence on a whole-body imager

    International Nuclear Information System (INIS)

    Listerud, J.; Lenkinski, R.E.; Axel, L.

    1989-01-01

    To define the lower limits of spatial resolution in gradient-recalled echo phosphorus studies at 1.5 T, the authors have implemented a phosphorus gradient-recalled imaging sequence on the Signa imager. All gradient ramps for the section-selective rephasing lobe, the phase-encoding pulse, and the dephasing pulse of the frequency-encoding gradient are slowed at the maximal rate. Consequently, with a field of view of 24 cm, an in-plane resolution of 3 cm, an echo appropriately offset, an RF bandwidth of 1.2 KHz, and a section thickness of 5 cm, the echo time may be reduced to 1.35 msec. The reconstruction algorithm has been modified to support oversampled data of low spatial resolution appropriate for phosphorus imaging. The sequence will acquire H-1 images and supports the automatic and manual prescan features of the commercial instrument. To facilitate setup in the phosphorus imaging mode the sequence supports the product spectroscopic mode with a DRESS (depth recalled surface coil spectroscopy) sequence and a section profile sequence for appropriate shimming, receiver characteristics, and averaging requirements. The suitability for adaptation of this sequence to three-dimensional chemical shift imaging is discussed

  12. Effect of Si additions on thermal stability and the phase transition sequence of sputtered amorphous alumina thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bolvardi, H.; Baben, M. to; Nahif, F.; Music, D., E-mail: music@mch.rwth-aachen.de; Schnabel, V.; Shaha, K. P.; Mráz, S.; Schneider, J. M. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Bednarcik, J.; Michalikova, J. [Deutsches Elektronen Synchrotron DESY, FS-PE group, Notkestrasse 85, D-22607 Hamburg (Germany)

    2015-01-14

    Si-alloyed amorphous alumina coatings having a silicon concentration of 0 to 2.7 at. % were deposited by combinatorial reactive pulsed DC magnetron sputtering of Al and Al-Si (90-10 at. %) split segments in Ar/O{sub 2} atmosphere. The effect of Si alloying on thermal stability of the as-deposited amorphous alumina thin films and the phase formation sequence was evaluated by using differential scanning calorimetry and X-ray diffraction. The thermal stability window of the amorphous phase containing 2.7 at. % of Si was increased by more than 100 °C compared to that of the unalloyed phase. A similar retarding effect of Si alloying was also observed for the α-Al{sub 2}O{sub 3} formation temperature, which increased by more than 120 °C. While for the latter retardation, the evidence for the presence of SiO{sub 2} at the grain boundaries was presented previously, this obviously cannot explain the stability enhancement reported here for the amorphous phase. Based on density functional theory molecular dynamics simulations and synchrotron X-ray diffraction experiments for amorphous Al{sub 2}O{sub 3} with and without Si incorporation, we suggest that the experimentally identified enhanced thermal stability of amorphous alumina with addition of Si is due to the formation of shorter and stronger Si–O bonds as compared to Al–O bonds.

  13. Effect of Si additions on thermal stability and the phase transition sequence of sputtered amorphous alumina thin films

    International Nuclear Information System (INIS)

    Bolvardi, H.; Baben, M. to; Nahif, F.; Music, D.; Schnabel, V.; Shaha, K. P.; Mráz, S.; Schneider, J. M.; Bednarcik, J.; Michalikova, J.

    2015-01-01

    Si-alloyed amorphous alumina coatings having a silicon concentration of 0 to 2.7 at. % were deposited by combinatorial reactive pulsed DC magnetron sputtering of Al and Al-Si (90-10 at. %) split segments in Ar/O 2 atmosphere. The effect of Si alloying on thermal stability of the as-deposited amorphous alumina thin films and the phase formation sequence was evaluated by using differential scanning calorimetry and X-ray diffraction. The thermal stability window of the amorphous phase containing 2.7 at. % of Si was increased by more than 100 °C compared to that of the unalloyed phase. A similar retarding effect of Si alloying was also observed for the α-Al 2 O 3 formation temperature, which increased by more than 120 °C. While for the latter retardation, the evidence for the presence of SiO 2 at the grain boundaries was presented previously, this obviously cannot explain the stability enhancement reported here for the amorphous phase. Based on density functional theory molecular dynamics simulations and synchrotron X-ray diffraction experiments for amorphous Al 2 O 3 with and without Si incorporation, we suggest that the experimentally identified enhanced thermal stability of amorphous alumina with addition of Si is due to the formation of shorter and stronger Si–O bonds as compared to Al–O bonds

  14. The Stellar Imager (SI) Project: Resolving Stellar Surfaces, Interiors, and Magnetic Activity

    Science.gov (United States)

    Carpenter, Kenneth G.; Schrijver, K.; Karovska, M.

    2007-01-01

    The Stellar Imager (SI) is a UV/Optical. Space-Based Interferometer designed to enable 0.1 milli-arcsec (mas) spectral imaging of stellar surfaces and, via asteroseismology, stellar interiors and of the Universe in general. The ultra-sharp images of SI will revolutionize our view of many dynamic astrophysical processes by transforming point sources into extended sources, and snapshots into evolving views. The science of SI focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. Its prime goal is to enable long-term forecasting of solar activity and the space weather that it drives. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. In this paper we discuss the science goals, technology needs, and baseline design of the SI mission.

  15. OBJECT-SPACE MULTI-IMAGE MATCHING OF MOBILE-MAPPING-SYSTEM IMAGE SEQUENCES

    Directory of Open Access Journals (Sweden)

    Y. C. Chen

    2012-07-01

    Full Text Available This paper proposes an object-space multi-image matching procedure of terrestrial MMS (Mobile Mapping System image sequences to determine the coordinates of an object point automatically and reliably. This image matching procedure can be applied to find conjugate points of MMS image sequences efficiently. Conventional area-based image matching methods are not reliable to deliver accurate matching results for this application due to image scale variations, viewing angle variations, and object occlusions. In order to deal with these three matching problems, an object space multi-image matching is proposed. A modified NCC (Normalized Cross Correlation coefficient is proposed to measure the similarity of image patches. A modified multi-window matching procedure will also be introduced to solve the problem of object occlusion. A coarse-to-fine procedure with a combination of object-space multi-image matching and multi-window matching is adopted. The proposed procedure has been implemented for the purpose of matching terrestrial MMS image sequences. The ratio of correct matches of this experiment was about 80 %. By providing an approximate conjugate point in an overlapping image manually, most of the incorrect matches could be fixed properly and the ratio of correct matches was improved up to 98 %.

  16. Development of a SiPM-based PET imaging system for small animals

    International Nuclear Information System (INIS)

    Lu, Yanye; Yang, Kun; Zhou, Kedi; Zhang, Qiushi; Pang, Bo; Ren, Qiushi

    2014-01-01

    Advances in small animal positron emission tomography (PET) imaging have been accelerated by many new technologies such as the successful incorporation of silicon photomultiplier (SiPM). In this paper, we have developed a compact, lightweight PET imaging system that is based on SiPM detectors for small animals imaging, which could be integrated into a multi-modality imaging system. This PET imaging system consists of a stationary detector gantry, a motor-controlled animal bed module, electronics modules, and power supply modules. The PET detector, which was designed as a multi-slice circular ring geometry of 27 discrete block detectors, is composed of a cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal and SiPM arrays. The system has a 60 mm transaxial field of view (FOV) and a 26 mm axial FOV. Performance tests (e.g. spatial resolution, energy resolution, and sensitivity) and phantom and animal imaging studies were performed to evaluate the imaging performance of the PET imaging system. The performance tests and animal imaging results demonstrate the feasibility of an animal PET system based on SiPM detectors and indicate that SiPM detectors can be promising photodetectors in animal PET instrumentation development

  17. Development of a SiPM-based PET imaging system for small animals

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yanye [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Yang, Kun, E-mail: yangkun9999@hotmail.com [Department of Control Technology and Instrumentation, College of Quality and Technical Supervision, Hebei University, Baoding, 071000 (China); Zhou, Kedi; Zhang, Qiushi; Pang, Bo [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Ren, Qiushi, E-mail: renqsh@coe.pku.edu.cn [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2014-04-11

    Advances in small animal positron emission tomography (PET) imaging have been accelerated by many new technologies such as the successful incorporation of silicon photomultiplier (SiPM). In this paper, we have developed a compact, lightweight PET imaging system that is based on SiPM detectors for small animals imaging, which could be integrated into a multi-modality imaging system. This PET imaging system consists of a stationary detector gantry, a motor-controlled animal bed module, electronics modules, and power supply modules. The PET detector, which was designed as a multi-slice circular ring geometry of 27 discrete block detectors, is composed of a cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal and SiPM arrays. The system has a 60 mm transaxial field of view (FOV) and a 26 mm axial FOV. Performance tests (e.g. spatial resolution, energy resolution, and sensitivity) and phantom and animal imaging studies were performed to evaluate the imaging performance of the PET imaging system. The performance tests and animal imaging results demonstrate the feasibility of an animal PET system based on SiPM detectors and indicate that SiPM detectors can be promising photodetectors in animal PET instrumentation development.

  18. Compression and Processing of Space Image Sequences of Northern Lights and Sprites

    DEFF Research Database (Denmark)

    Forchhammer, Søren Otto; Martins, Bo; Jensen, Ole Riis

    1999-01-01

    Compression of image sequences of auroral activity as northern lights and thunderstorms with sprites is investigated.......Compression of image sequences of auroral activity as northern lights and thunderstorms with sprites is investigated....

  19. Placental fetal stem segmentation in a sequence of histology images

    Science.gov (United States)

    Athavale, Prashant; Vese, Luminita A.

    2012-02-01

    Recent research in perinatal pathology argues that analyzing properties of the placenta may reveal important information on how certain diseases progress. One important property is the structure of the placental fetal stems. Analysis of the fetal stems in a placenta could be useful in the study and diagnosis of some diseases like autism. To study the fetal stem structure effectively, we need to automatically and accurately track fetal stems through a sequence of digitized hematoxylin and eosin (H&E) stained histology slides. There are many problems in successfully achieving this goal. A few of the problems are: large size of images, misalignment of the consecutive H&E slides, unpredictable inaccuracies of manual tracing, very complicated texture patterns of various tissue types without clear characteristics, just to name a few. In this paper we propose a novel algorithm to achieve automatic tracing of the fetal stem in a sequence of H&E images, based on an inaccurate manual segmentation of a fetal stem in one of the images. This algorithm combines global affine registration, local non-affine registration and a novel 'dynamic' version of the active contours model without edges. We first use global affine image registration of all the images based on displacement, scaling and rotation. This gives us approximate location of the corresponding fetal stem in the image that needs to be traced. We then use the affine registration algorithm "locally" near this location. At this point, we use a fast non-affine registration based on L2-similarity measure and diffusion regularization to get a better location of the fetal stem. Finally, we have to take into account inaccuracies in the initial tracing. This is achieved through a novel dynamic version of the active contours model without edges where the coefficients of the fitting terms are computed iteratively to ensure that we obtain a unique stem in the segmentation. The segmentation thus obtained can then be used as an

  20. Human genome sequencing with direct x-ray holographic imaging

    International Nuclear Information System (INIS)

    Rhodes, C.K.

    1993-01-01

    Direct holographic imaging of biological materials is widely applicable to the study of the structure, properties and action of genetic material. This particular application involves the sequencing of the human genome where prospective genomic imaging technology is composed of three subtechnologies, name an x-ray holographic camera, suitable chemistry and enzymology for the preparation of tagged DNA samples, and the illuminator in the form of an x-ray laser. We report appropriate x-ray camera, embodied by the instrument developed by MCR, is available and that suitable chemical and enzymatic procedures exist for the preparation of the necessary tagged DNA strands. Concerning the future development of the x-ray illuminator. We find that a practical small scale x-ray light source is indeed feasible. This outcome requires the use of unconventional physical processes in order to achieve the necessary power-compression in the amplifying medium. The understanding of these new physical mechanisms is developing rapidly. Importantly, although the x-ray source does not currently exist, the understanding of these new physical mechanisms is developing rapidly and the research has established the basic scaling laws that will determine the properties of the x-ray illuminator. When this x-ray source becomes available, an extremely rapid and cost effective instrument for 3-D imaging of biological materials can be applied to a wide range of biological structural assays, including the base-pair sequencing of the human genome and many questions regarding its higher levels of organization

  1. Advances in digital SiPMs and their application in biomedical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Schaart, Dennis R., E-mail: d.r.schaart@tudelft.nl [Delft University of Technology, Faculty of Applied Sciences, Radiation Science and Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Charbon, Edoardo [Delft University of Technology, Faculty of Electrical Engineering, Circuits and Systems, Mekelweg 4, 2628 CD Delft (Netherlands); Frach, Thomas [Philips Digital Photon Counting, Pauwelsstraße 17, 52074 Aachen (Germany); Schulz, Volkmar [Department for Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Germany and Philips Research Europe, Aachen (Germany)

    2016-02-11

    Similar to analog silicon photomultipliers (SiPMs), digital SiPMs (dSiPMs) essentially consist of an array of single-photon avalanche photodiodes (SPADs). Instead of a passive quench resistor, however, an active quenching circuit is locally integrated with each SPAD, making the sensor response faster and less sensitive to the gains of the individual SPADs. Moreover, additional circuits for the fully digital acquisition, processing, and readout of optical signals are integrated within the sensor. As a result, dSiPMs offer high photo-detection efficiency, high single-photon time resolution (SPTR), and high uniformity, as well as many practical advantages, such as a very compact form factor, low voltage operation, magnetic field compatibility, high stability of operation, low gain drift, and a high degree of scalability. At the same time, dSiPMs represent a new paradigm in low-level light sensing technology. That is, their fully digital operation makes them true photon counting devices, preserving at least partly the discrete spatio-temporal structure of the information embedded in the optical signal. This means that the operation of dSiPMs can be fully understood only in statistical terms, but also opens up novel possibilities for extracting information from the measured data. So far, the main driver behind the development of dSiPMs has been the detection of scintillation pulses in detectors for time-of-flight (TOF) positron emission tomography (PET). Several types of dSiPM have been developed in recent years. Moreover, first imaging devices based on dSiPMs have been realized by various groups. This review summarizes the main dSiPM concepts and technologies currently under development, provides an overview of the results obtained recently with dSiPMs-based PET and SPECT devices, and presents a critical outlook on the challenges and chances for dSiPMs in future radiomolecular imaging systems.

  2. Superresolution restoration of an image sequence: adaptive filtering approach.

    Science.gov (United States)

    Elad, M; Feuer, A

    1999-01-01

    This paper presents a new method based on adaptive filtering theory for superresolution restoration of continuous image sequences. The proposed methodology suggests least squares (LS) estimators which adapt in time, based on adaptive filters, least mean squares (LMS) or recursive least squares (RLS). The adaptation enables the treatment of linear space and time-variant blurring and arbitrary motion, both of them assumed known. The proposed new approach is shown to be of relatively low computational requirements. Simulations demonstrating the superresolution restoration algorithms are presented.

  3. The Stellar Imager (SI) - A Mission to Resolve Stellar Surfaces, Interiors, and Magnetic Activity

    International Nuclear Information System (INIS)

    Christensen-Dalsgaard, Joergen; Carpenter, Kenneth G; Schrijver, Carolus J; Karovska, Margarita

    2011-01-01

    The Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general. It will also probe via asteroseismology flows and structures in stellar interiors. SI will enable the development and testing of a predictive dynamo model for the Sun, by observing patterns of surface activity and imaging of the structure and differential rotation of stellar interiors in a population study of Sun-like stars to determine the dependence of dynamo action on mass, internal structure and flows, and time. SI's science focuses on the role of magnetism in the Universe and will revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. SI is a 'Landmark/Discovery Mission' in the 2005 Heliophysics Roadmap, an implementation of the UVOI in the 2006 Astrophysics Strategic Plan, and a NASA Vision Mission ('NASA Space Science Vision Missions' (2008), ed. M. Allen). We present here the science goals of the SI Mission, a mission architecture that could meet those goals, and the technology development needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/.

  4. The Stellar Imager (SI) - A Mission to Resolve Stellar Surfaces, Interiors, and Magnetic Activity

    Energy Technology Data Exchange (ETDEWEB)

    Christensen-Dalsgaard, Joergen [Department of Physics and Astronomy, Aarhus University (Denmark); Carpenter, Kenneth G [Code 667 NASA-GSFC, Greenbelt, MD 20771 (United States); Schrijver, Carolus J [LMATC 3251 Hanover St., Bldg. 252, Palo Alto, CA 94304 (United States); Karovska, Margarita, E-mail: jcd@phys.au.d, E-mail: Kenneth.G.Carpenter@nasa.gov, E-mail: schryver@lmsal.com, E-mail: karovska@head.cfa.harvard.edu [60 Garden St., Cambridge, MA 02138 (United States)

    2011-01-01

    The Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general. It will also probe via asteroseismology flows and structures in stellar interiors. SI will enable the development and testing of a predictive dynamo model for the Sun, by observing patterns of surface activity and imaging of the structure and differential rotation of stellar interiors in a population study of Sun-like stars to determine the dependence of dynamo action on mass, internal structure and flows, and time. SI's science focuses on the role of magnetism in the Universe and will revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. SI is a 'Landmark/Discovery Mission' in the 2005 Heliophysics Roadmap, an implementation of the UVOI in the 2006 Astrophysics Strategic Plan, and a NASA Vision Mission ('NASA Space Science Vision Missions' (2008), ed. M. Allen). We present here the science goals of the SI Mission, a mission architecture that could meet those goals, and the technology development needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/.

  5. The Stellar Imager (SI) - A Mission to Resolve Stellar Surfaces, Interiors, and Magnetic Activity

    Science.gov (United States)

    Christensen-Dalsgaard, Jørgen; Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita; Si Team

    2011-01-01

    The Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general. It will also probe via asteroseismology flows and structures in stellar interiors. SI will enable the development and testing of a predictive dynamo model for the Sun, by observing patterns of surface activity and imaging of the structure and differential rotation of stellar interiors in a population study of Sun-like stars to determine the dependence of dynamo action on mass, internal structure and flows, and time. SI's science focuses on the role of magnetism in the Universe and will revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. SI is a "Landmark/Discovery Mission" in the 2005 Heliophysics Roadmap, an implementation of the UVOI in the 2006 Astrophysics Strategic Plan, and a NASA Vision Mission ("NASA Space Science Vision Missions" (2008), ed. M. Allen). We present here the science goals of the SI Mission, a mission architecture that could meet those goals, and the technology development needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/.

  6. Safety Assessment of Advanced Imaging Sequences II: Simulations

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2016-01-01

    .6%, when using the impulse response of the probe estimated from an independent measurement. The accuracy is increased to between -22% to 24.5% for MI and between -33.2% to 27.0% for Ispta.3, when using the pressure response measured at a single point to scale the simulation. The spatial distribution of MI...... Mechanical Index (MI) and Ispta.3 as required by FDA. The method is performed on four different imaging schemes and compared to measurements conducted using the SARUS experimental scanner. The sequences include focused emissions with an F-number of 2 with 64 elements that generate highly non-linear fields....... The simulation time is between 0.67 ms to 2.8 ms per emission and imaging point, making it possible to simulate even complex emission sequences in less than 1 s for a single spatial position. The linear simulations yield a relative accuracy on MI between -12.1% to 52.3% and for Ispta.3 between -38.6% to 62...

  7. Supervised detection of exoplanets in high-contrast imaging sequences

    Science.gov (United States)

    Gomez Gonzalez, C. A.; Absil, O.; Van Droogenbroeck, M.

    2018-06-01

    Context. Post-processing algorithms play a key role in pushing the detection limits of high-contrast imaging (HCI) instruments. State-of-the-art image processing approaches for HCI enable the production of science-ready images relying on unsupervised learning techniques, such as low-rank approximations, for generating a model point spread function (PSF) and subtracting the residual starlight and speckle noise. Aims: In order to maximize the detection rate of HCI instruments and survey campaigns, advanced algorithms with higher sensitivities to faint companions are needed, especially for the speckle-dominated innermost region of the images. Methods: We propose a reformulation of the exoplanet detection task (for ADI sequences) that builds on well-established machine learning techniques to take HCI post-processing from an unsupervised to a supervised learning context. In this new framework, we present algorithmic solutions using two different discriminative models: SODIRF (random forests) and SODINN (neural networks). We test these algorithms on real ADI datasets from VLT/NACO and VLT/SPHERE HCI instruments. We then assess their performances by injecting fake companions and using receiver operating characteristic analysis. This is done in comparison with state-of-the-art ADI algorithms, such as ADI principal component analysis (ADI-PCA). Results: This study shows the improved sensitivity versus specificity trade-off of the proposed supervised detection approach. At the diffraction limit, SODINN improves the true positive rate by a factor ranging from 2 to 10 (depending on the dataset and angular separation) with respect to ADI-PCA when working at the same false-positive level. Conclusions: The proposed supervised detection framework outperforms state-of-the-art techniques in the task of discriminating planet signal from speckles. In addition, it offers the possibility of re-processing existing HCI databases to maximize their scientific return and potentially improve

  8. Modeling of Precipitation Sequence and Ageing Kinetics in Al-Mg-Si Alloys

    NARCIS (Netherlands)

    Bahrami, A.

    2010-01-01

    Al-Mg-Si alloys are heat treatable alloys in which strength is obtained by precipitation hardening. Precipitates, formed from a supersaturated solid solution during ageing heat treatment, are GP-zones, B", B´ and B-Mg2Si. Precipitation kinetics and strength vary with alloy composition and process

  9. Fluorescence imaging as a diagnostic of M-band x-ray drive condition in hohlraum with fluorescent Si targets

    International Nuclear Information System (INIS)

    Li, Qi; Hu, Zhimin; Yao, Li; Huang, Chengwu; Yuan, Zheng; Zhao, Yang; Xiong, Gang; Qing, Bo; Lv, Min; Zhu, Tuo; Deng, Bo; Li, Jin; Wei, Minxi; Zhan, Xiayu; Li, Jun; Yang, Yimeng; Su, Chunxiao; Yang, Guohong; Zhang, Jiyan; Li, Sanwei

    2017-01-01

    Fluorescence imaging of surrogate Si-doped CH targets has been used to provide a measurement for drive condition of high-energy x-ray (i.e. M-band x-ray) drive symmetry upon the capsule in hohlraum on Shenguang-II laser facility. A series of experiments dedicated to the study of photo-pumping and fluorescence effect in Si-plasma are presented. To investigate the feasibility of fluorescence imaging in Si-plasma, an silicon plasma in Si-foil target is pre-formed at ground state by the soft x-ray from a half-hohlraum, which is then photo-pumped by the K-shell lines from a spatially distinct laser-produced Si-plasma. The resonant Si photon pump is used to improve the fluorescence signal and cause visible image in the Si-foil. Preliminary fluorescence imaging of Si-ball target is performed in both Si-doped and pure Au hohlraum. The usual capsule at the center of the hohlraum is replaced with a solid Si-doped CH-ball (Si-ball). Since the fluorescence is proportional to the photon pump upon the Si-plasma, high-energy x-ray drive symmetry is equal to the fluorescence distribution of the Si-ball. (paper)

  10. Performance evaluation of SiPM photodetectors for PET imaging in the presence of magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Espana, S., E-mail: samuel@nuclear.fis.ucm.e [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Fraile, L.M.; Herraiz, J.L.; Udias, J.M. [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Desco, M.; Vaquero, J.J. [Unidad de Medicina y Cirugia Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain)

    2010-02-01

    The multi-pixel photon counter (MPPC) or silicon photomultiplier (SiPM), recently introduced as a solid-state photodetector, consists of an array of Geiger-mode photodiodes (microcells). It is a promising device for PET due to its potential for high photon detection efficiency (PDE) and its foreseeable immunity to magnetic fields. It is also easy to use with simple read-outs, has a high gain and a small size. In this work we evaluate the in field performance of three 1x1 mm{sup 2} (with 100, 400 and 1600 microcells, respectively) and one 6x6 mm{sup 2} (arranged as a 2x2 array) Hamamatsu MPPCs for their use in PET imaging. We examine the dependence of the energy resolution and the gain of these devices on the temperature and reverse bias voltage, when coupled to LYSO scintillator crystals under conditions that one would find in a PET system. We find that the 400 and 1600 microcells models and the 2x2 array are suitable for small-size crystals, like those employed in high resolution small animal scanners. We have confirmed the good performance of these devices up to magnetic fields of 7 T as well as their suitability for performing PET acquisitions in the presence of fast switching gradients and high duty radiofrequency MRI sequences.

  11. Holistic and component plant phenotyping using temporal image sequence.

    Science.gov (United States)

    Das Choudhury, Sruti; Bashyam, Srinidhi; Qiu, Yumou; Samal, Ashok; Awada, Tala

    2018-01-01

    Image-based plant phenotyping facilitates the extraction of traits noninvasively by analyzing large number of plants in a relatively short period of time. It has the potential to compute advanced phenotypes by considering the whole plant as a single object (holistic phenotypes) or as individual components, i.e., leaves and the stem (component phenotypes), to investigate the biophysical characteristics of the plants. The emergence timing, total number of leaves present at any point of time and the growth of individual leaves during vegetative stage life cycle of the maize plants are significant phenotypic expressions that best contribute to assess the plant vigor. However, image-based automated solution to this novel problem is yet to be explored. A set of new holistic and component phenotypes are introduced in this paper. To compute the component phenotypes, it is essential to detect the individual leaves and the stem. Thus, the paper introduces a novel method to reliably detect the leaves and the stem of the maize plants by analyzing 2-dimensional visible light image sequences captured from the side using a graph based approach. The total number of leaves are counted and the length of each leaf is measured for all images in the sequence to monitor leaf growth. To evaluate the performance of the proposed algorithm, we introduce University of Nebraska-Lincoln Component Plant Phenotyping Dataset (UNL-CPPD) and provide ground truth to facilitate new algorithm development and uniform comparison. The temporal variation of the component phenotypes regulated by genotypes and environment (i.e., greenhouse) are experimentally demonstrated for the maize plants on UNL-CPPD. Statistical models are applied to analyze the greenhouse environment impact and demonstrate the genetic regulation of the temporal variation of the holistic phenotypes on the public dataset called Panicoid Phenomap-1. The central contribution of the paper is a novel computer vision based algorithm for

  12. Particle tracking from image sequences of complex plasma crystals

    International Nuclear Information System (INIS)

    Hadziavdic, Vedad; Melandsoe, Frank; Hanssen, Alfred

    2006-01-01

    In order to gather information about the physics of the complex plasma crystals from the experimental data, particles have to be tracked through a sequence of images. An application of the Kalman filter for that purpose is presented, using a one-dimensional approximation of the particle dynamics as a model for the filter. It is shown that Kalman filter is capable of tracking dust particles even with high levels of measurement noise. An inherent part of the Kalman filter, the innovation process, can be used to estimate values of the physical system parameters from the experimental data. The method is shown to be able to estimate the characteristic oscillation frequency from noisy data

  13. Optical imaging of absorption and distribution of RITC-SiO2 nanoparticles after oral administration

    Directory of Open Access Journals (Sweden)

    Lee CM

    2014-12-01

    Full Text Available Chang-Moon Lee,1 Tai Kyoung Lee,2–5 Dae-Ik Kim,1,6 Yu-Ri Kim,7 Meyoung-Kon Kim,7 Hwan-Jeong Jeong,2–5 Myung-Hee Sohn,2–5 Seok Tae Lim2–5 1Department of Biomedical Engineering, Chonnam National University, Yeosu, Jeollanam-Do, Republic of Korea; 2Department of Nuclear Medicine, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-Do, Republic of Korea; 3Cyclotron Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-Do, Republic of Korea; 4Biomedical Research Institute, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-Do, Republic of Korea; 5Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-Do, Republic of Korea; 6School of Electrical, Electronic Communication, and Computer Engineering, Chonnam National University, Yeosu, Jeollanam-Do, Republic of Korea; 7Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seounbuk-Gu, Seoul, Republic of Korea Purpose: In this study, we investigated the absorption and distribution of rhodamine B isothiocyanate (RITC-incorporated silica oxide nanoparticles(SiNPs (RITC-SiNPs after oral exposure, by conducting optical imaging, with a focus on tracking the movement of RITC-SiNPs of different particle size and surface charge. Methods: RITC-SiNPs (20 or 100 nm; positively or negatively charged were used to avoid the dissociation of a fluorescent dye from nanoparticles via spontaneous or enzyme-catalyzed reactions in vivo. The changes in the nanoparticle sizes and shapes were investigated in an HCl solution for 6 hours. RITC-SiNPs were orally administered to healthy nude mice at a dose of 100 mg/kg. Optical imaging studies were performed at 2, 4, and 6 hours after oral administration. The mice were sacrificed at 2, 4, 6, and 10 hours post-administration, and ex vivo imaging studies were performed

  14. Fast T1-weighted imaging using GRASE sequence for the female pelvis

    International Nuclear Information System (INIS)

    Dohke, Masako; Watanabe, Yuji; Kumashiro, Masayuki; Amoh, Yoshiki; Ishimori, Takayoshi; Oda, Kazushige; Okumura, Akira; Koike, Shinji; Dodo, Yoshihiro

    1998-01-01

    GRASE sequence, a combination of TSE and gradient echo, has been developed as a fast T 2 -weighted imaging technique. We have modified the GRASE sequence to be used for fast T 1 -weighted imaging of the female pelvis. In this article, we compared image quality and incidence of artifacts between T 1 -weighted GRASE images and conventional T 1 -weighted SE images. In a phantom study, signal-to-noise ratio was inferior in the GRASE images relative to corresponding on SE images. Susceptibility and chemical shift artifacts seen in GRASE images were seen with almost equal incidence in SE and TSE images. In a clinical study, we compared GRASE images with SE images in six patients with endometrial cysts and four patients with dermoid cysts. The overall image quality obtained with GRASE sequence was satisfactory in all patients and was almost identical with that obtained with SE sequence. GRASE images demonstrated endometrial cysts and dermoid cysts as clearly as did SE images. T 1 -weighted GRASE imaging, however, has a relatively long TE (35 ms) for T 1 -weighted images, which makes the signal intensity of urine and uterine endometrium with long T 2 values higher than in SE images. In conclusion, GRASE sequence can be used for fast T 1 -weighted imaging of the female pelvis because of short imaging time. (author)

  15. Three-dimensional atomic-image reconstruction from a single-energy Si(100) photoelectron hologram

    International Nuclear Information System (INIS)

    Matsushita, T.; Agui, A.; Yoshigoe, A.

    2004-01-01

    Full text: J. J. Barton proposed a basic algorithm for three-dimensional atomic-image reconstruction from photoelectron hologram, which is based on the Fourier transform(FT). In the use of a single-energy hologram, the twin-image appears in principle. The twin image disappears in the use of multi-energy hologram, which requires longer measuring time and variable-energy light source. But the reconstruction in the use of a simple FT is difficult because the scattered electron wave is not s-symmetric wave. Many theoretical and experimental approaches based on the FT have been researched. We propose a new algorithm so-called 'scattering pattern matrix', which is not based on the FT. The algorithm utilizes the 'scattering pattern', and iterative gradient method. Real space image can be reconstructed from a single-energy hologram without initial model. In addition, the twin image disappears. We reconstructed the three-dimensional atomic image of Si bulk structure from an experimental single-energy hologram of Si(100) 2s emission, which is shown The experiment was performed with using a Al-K α light source. The experimental setup is shown in. Then we calculated a vertical slice image of the reconstructed Si bulk structure, which is shown. The atomic images appear around the expected positions

  16. The Stellar Imager (SI) - A Mission to Resolve Stellar Surfaces, Interiors, and Magnetic Activity

    Science.gov (United States)

    Christensen-Dalsgaard, Jorgen; Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita

    2012-01-01

    The Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general. It will also probe via asteroseismology flows and structures in stellar interiors. SI will enable the development and testing of a predictive dynamo model for the Sun, by observing patterns of surface activity and imaging of the structure and differential rotation of stellar interiors in a population study of Sun-like stars to determine the dependence of dynamo action on mass, internal structure and flows, and time. SI's science focuses on the role of magnetism in the Universe and will revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magnetohydrodynamically controlled processes in the Universe. SI is a "LandmarklDiscovery Mission" in the 2005 Heliophysics Roadmap, an implementation of the UVOI in the 2006 Astrophysics Strategic Plan, and a NASA Vision Mission ("NASA Space Science Vision Missions" (2008), ed. M. Allen). We present here the science goals of the SI Mission, a mission architecture that could meet those goals, and the technology development needed to enable this mission

  17. Application of a-Si:H radiation detectors in medical imaging

    International Nuclear Information System (INIS)

    Lee, Hyoung-Koo.

    1995-06-01

    Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 ∼ 2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered γ-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at -26C. The thermal generation current in reverse biased a-Si:H p-i-n photodetectors was investigated, and the Poole-Frenkel effect was found to be the most significant source of the thermal generation current. Based on the Poole-Frenkel effect, voltage- and time-dependent thermal generation current was modeled. Using the model, the operating conditions of the proposed a-Si:H gamma camera, such as the operating temperature, the operating bias and the γ-scan period, could be predicted. The transient photoconductive gain mechanism in various a-Si:H devices was investigated for applications in digital radiography. Using the a-Si:H photoconductors in n-i-n configuration in pixel arrays, enhancement in signal collection (more than 200 times higher signal level) can be achieved in digital radiography, compared to the ordinary p-i-n type a-Si:H x-ray imaging arrays

  18. Si and gaas pixel detectors for medical imaging applications

    International Nuclear Information System (INIS)

    Bisogni, M. G.

    2001-01-01

    As the use of digital radiographic equipment in the morphological imaging field is becoming the more and more diffuse, the research of new and more performing devices from public institutions and industrial companies is in constant progress. Most of these devices are based on solid-state detectors as X-ray sensors. Semiconductor pixel detectors, originally developed in the high energy physics environment, have been then proposed as digital detector for medical imaging applications. In this paper a digital single photon counting device, based on silicon and GaAs pixel detector, is presented. The detector is a thin slab of semiconductor crystal where an array of 64 by 64 square pixels, 170- m side, has been built on one side. The data read-out is performed by a VLSI integrated circuit named Photon Counting Chip (PCC), developed within the MEDIPIX collaboration. Each chip cell geometrically matches the sensor pixel. It contains a charge preamplifier, a threshold comparator and a 15 bits pseudo-random counter and it is coupled to the detector by means of bump bonding. Most important advantages of such system, with respect to a traditional X-rays film/screen device, are the wider linear dynamic range (3x104) and the higher performance in terms of MTF and DQE. Besides the single photon counting architecture allows to detect image contrasts lower than 3%. Electronics read-out performance as well as imaging capabilities of the digital device will be presented. Images of mammographic phantoms acquired with a standard Mammographic tube will be compared with radiographs obtained with traditional film/screen systems

  19. Proof of concept of an imaging system demonstrator for PET applications with SiPM

    International Nuclear Information System (INIS)

    Morrocchi, Matteo; Marcatili, Sara; Belcari, Nicola; Giuseppina Bisogni, Maria; Collazuol, Gianmaria; Ambrosi, Giovanni; Santoni, Cristiano; Corsi, Francesco; Foresta, Maurizio; Marzocca, Cristoforo; Matarrese, Gianvito; Sportelli, Giancarlo; Guerra, Pedro; Santos, Andres; Del Guerra, Alberto

    2013-01-01

    A PET imaging system demonstrator based on LYSO crystal arrays coupled to SiPM matrices is under construction at the University and INFN of Pisa. Two SiPM matrices, composed of 8×8 SiPM pixels, and 1,5 mm pitch, have been coupled one to one to a LYSO crystals array and read out by a custom electronics system. front-end ASICs were used to read 8 channels of each matrix. Data from each front-end were multiplexed and sent to a DAQ board for the digital conversion; a motherboard collects the data and communicates with a host computer through a USB port for the storage and off-line data processing. In this paper we show the first preliminary tomographic image of a point-like radioactive source acquired with part of the two detection heads in time coincidence

  20. Proof of concept of an imaging system demonstrator for PET applications with SiPM

    Energy Technology Data Exchange (ETDEWEB)

    Morrocchi, Matteo, E-mail: matteo.morrocchi@pi.infn.it [University of Pisa and INFN Sezione di Pisa, Pisa 56127 (Italy); Marcatili, Sara; Belcari, Nicola; Giuseppina Bisogni, Maria [University of Pisa and INFN Sezione di Pisa, Pisa 56127 (Italy); Collazuol, Gianmaria [INFN Sezione di Pisa, Pisa 56127 (Italy); Ambrosi, Giovanni; Santoni, Cristiano [INFN Sezione di Perugia, Perugia 06100 (Italy); Corsi, Francesco; Foresta, Maurizio; Marzocca, Cristoforo; Matarrese, Gianvito [Politecnico di Bari and INFN Sezione di Bari, Bari 70100 (Italy); Sportelli, Giancarlo [University of Pisa and INFN Sezione di Pisa, Pisa 56127 (Italy); Guerra, Pedro; Santos, Andres [Universidad Politecnica de Madrid, E 28040 Madrid (Spain); Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN) (Spain); Del Guerra, Alberto [University of Pisa and INFN Sezione di Pisa, Pisa 56127 (Italy)

    2013-08-21

    A PET imaging system demonstrator based on LYSO crystal arrays coupled to SiPM matrices is under construction at the University and INFN of Pisa. Two SiPM matrices, composed of 8×8 SiPM pixels, and 1,5 mm pitch, have been coupled one to one to a LYSO crystals array and read out by a custom electronics system. front-end ASICs were used to read 8 channels of each matrix. Data from each front-end were multiplexed and sent to a DAQ board for the digital conversion; a motherboard collects the data and communicates with a host computer through a USB port for the storage and off-line data processing. In this paper we show the first preliminary tomographic image of a point-like radioactive source acquired with part of the two detection heads in time coincidence.

  1. Real-time SPARSE-SENSE cardiac cine MR imaging: optimization of image reconstruction and sequence validation.

    Science.gov (United States)

    Goebel, Juliane; Nensa, Felix; Bomas, Bettina; Schemuth, Haemi P; Maderwald, Stefan; Gratz, Marcel; Quick, Harald H; Schlosser, Thomas; Nassenstein, Kai

    2016-12-01

    Improved real-time cardiac magnetic resonance (CMR) sequences have currently been introduced, but so far only limited practical experience exists. This study aimed at image reconstruction optimization and clinical validation of a new highly accelerated real-time cine SPARSE-SENSE sequence. Left ventricular (LV) short-axis stacks of a real-time free-breathing SPARSE-SENSE sequence with high spatiotemporal resolution and of a standard segmented cine SSFP sequence were acquired at 1.5 T in 11 volunteers and 15 patients. To determine the optimal iterations, all volunteers' SPARSE-SENSE images were reconstructed using 10-200 iterations, and contrast ratios, image entropies, and reconstruction times were assessed. Subsequently, the patients' SPARSE-SENSE images were reconstructed with the clinically optimal iterations. LV volumetric values were evaluated and compared between both sequences. Sufficient image quality and acceptable reconstruction times were achieved when using 80 iterations. Bland-Altman plots and Passing-Bablok regression showed good agreement for all volumetric parameters. 80 iterations are recommended for iterative SPARSE-SENSE image reconstruction in clinical routine. Real-time cine SPARSE-SENSE yielded comparable volumetric results as the current standard SSFP sequence. Due to its intrinsic low image acquisition times, real-time cine SPARSE-SENSE imaging with iterative image reconstruction seems to be an attractive alternative for LV function analysis. • A highly accelerated real-time CMR sequence using SPARSE-SENSE was evaluated. • SPARSE-SENSE allows free breathing in real-time cardiac cine imaging. • For clinically optimal SPARSE-SENSE image reconstruction, 80 iterations are recommended. • Real-time SPARSE-SENSE imaging yielded comparable volumetric results as the reference SSFP sequence. • The fast SPARSE-SENSE sequence is an attractive alternative to standard SSFP sequences.

  2. Restoring defect structures in 3C-SiC/Si (001) from spherical aberration-corrected high-resolution transmission electron microscope images by means of deconvolution processing.

    Science.gov (United States)

    Wen, C; Wan, W; Li, F H; Tang, D

    2015-04-01

    The [110] cross-sectional samples of 3C-SiC/Si (001) were observed with a spherical aberration-corrected 300 kV high-resolution transmission electron microscope. Two images taken not close to the Scherzer focus condition and not representing the projected structures intuitively were utilized for performing the deconvolution. The principle and procedure of image deconvolution and atomic sort recognition are summarized. The defect structure restoration together with the recognition of Si and C atoms from the experimental images has been illustrated. The structure maps of an intrinsic stacking fault in the area of SiC, and of Lomer and 60° shuffle dislocations at the interface have been obtained at atomic level. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Algorithms for detection of objects in image sequences captured from an airborne imaging system

    Science.gov (United States)

    Kasturi, Rangachar; Camps, Octavia; Tang, Yuan-Liang; Devadiga, Sadashiva; Gandhi, Tarak

    1995-01-01

    This research was initiated as a part of the effort at the NASA Ames Research Center to design a computer vision based system that can enhance the safety of navigation by aiding the pilots in detecting various obstacles on the runway during critical section of the flight such as a landing maneuver. The primary goal is the development of algorithms for detection of moving objects from a sequence of images obtained from an on-board video camera. Image regions corresponding to the independently moving objects are segmented from the background by applying constraint filtering on the optical flow computed from the initial few frames of the sequence. These detected regions are tracked over subsequent frames using a model based tracking algorithm. Position and velocity of the moving objects in the world coordinate is estimated using an extended Kalman filter. The algorithms are tested using the NASA line image sequence with six static trucks and a simulated moving truck and experimental results are described. Various limitations of the currently implemented version of the above algorithm are identified and possible solutions to build a practical working system are investigated.

  4. A Stochastic Approach for Blurred Image Restoration and Optical Flow Computation on Field Image Sequence

    Institute of Scientific and Technical Information of China (English)

    高文; 陈熙霖

    1997-01-01

    The blur in target images caused by camera vibration due to robot motion or hand shaking and by object(s) moving in the background scene is different to deal with in the computer vision system.In this paper,the authors study the relation model between motion and blur in the case of object motion existing in video image sequence,and work on a practical computation algorithm for both motion analysis and blut image restoration.Combining the general optical flow and stochastic process,the paper presents and approach by which the motion velocity can be calculated from blurred images.On the other hand,the blurred image can also be restored using the obtained motion information.For solving a problem with small motion limitation on the general optical flow computation,a multiresolution optical flow algoritm based on MAP estimation is proposed. For restoring the blurred image ,an iteration algorithm and the obtained motion velocity are used.The experiment shows that the proposed approach for both motion velocity computation and blurred image restoration works well.

  5. Quantitative comparison between a multiecho sequence and a single-echo sequence for susceptibility-weighted phase imaging.

    Science.gov (United States)

    Gilbert, Guillaume; Savard, Geneviève; Bard, Céline; Beaudoin, Gilles

    2012-06-01

    The aim of this study was to investigate the benefits arising from the use of a multiecho sequence for susceptibility-weighted phase imaging using a quantitative comparison with a standard single-echo acquisition. Four healthy adult volunteers were imaged on a clinical 3-T system using a protocol comprising two different three-dimensional susceptibility-weighted gradient-echo sequences: a standard single-echo sequence and a multiecho sequence. Both sequences were repeated twice in order to evaluate the local noise contribution by a subtraction of the two acquisitions. For the multiecho sequence, the phase information from each echo was independently unwrapped, and the background field contribution was removed using either homodyne filtering or the projection onto dipole fields method. The phase information from all echoes was then combined using a weighted linear regression. R2 maps were also calculated from the multiecho acquisitions. The noise standard deviation in the reconstructed phase images was evaluated for six manually segmented regions of interest (frontal white matter, posterior white matter, globus pallidus, putamen, caudate nucleus and lateral ventricle). The use of the multiecho sequence for susceptibility-weighted phase imaging led to a reduction of the noise standard deviation for all subjects and all regions of interest investigated in comparison to the reference single-echo acquisition. On average, the noise reduction ranged from 18.4% for the globus pallidus to 47.9% for the lateral ventricle. In addition, the amount of noise reduction was found to be strongly inversely correlated to the estimated R2 value (R=-0.92). In conclusion, the use of a multiecho sequence is an effective way to decrease the noise contribution in susceptibility-weighted phase images, while preserving both contrast and acquisition time. The proposed approach additionally permits the calculation of R2 maps. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Quantitative imaging of trace B in Si and SiO2 using ToF-SIMS

    International Nuclear Information System (INIS)

    Smentkowski, Vincent S.

    2015-01-01

    Changes in the oxidation state of an element can result in significant changes in the ionization efficiency and hence signal intensity during secondary ion mass spectrometry (SIMS) analysis; this is referred to as the SIMS matrix effect [Secondary Ion Mass Spectrometry: A Practical Handbook for Depth Profiling and Bulk Impurity Analysis, edited by R. G. Wilson, F. A. Stevie, and C. W. Magee (Wiley, New York, 1990)]. The SIMS matrix effect complicates quantitative analysis. Quantification of SIMS data requires the determination of relative sensitivity factors (RSFs), which can be used to convert the as measured intensity into concentration units [Secondary Ion Mass Spectrometry: A Practical Handbook for Depth Profiling and Bulk Impurity Analysis, edited by R. G. Wilson, F. A. Stevie, and C. W. Magee (Wiley, New York, 1990)]. In this manuscript, the authors report both: RSFs which were determined for quantification of B in Si and SiO 2 matrices using a dual beam time of flight secondary ion mass spectrometry (ToF-SIMS) instrument and the protocol they are using to provide quantitative ToF-SIMS images and line scan traces. The authors also compare RSF values that were determined using oxygen and Ar ion beams for erosion, discuss the problems that can be encountered when bulk calibration samples are used to determine RSFs, and remind the reader that errors in molecular details of the matrix (density, volume, etc.) that are used to convert from atoms/cm 3 to other concentration units will propagate into errors in the determined concentrations

  7. Comparative high-throughput transcriptome sequencing and development of SiESTa, the Silene EST annotation database

    Directory of Open Access Journals (Sweden)

    Marais Gabriel AB

    2011-07-01

    Full Text Available Abstract Background The genus Silene is widely used as a model system for addressing ecological and evolutionary questions in plants, but advances in using the genus as a model system are impeded by the lack of available resources for studying its genome. Massively parallel sequencing cDNA has recently developed into an efficient method for characterizing the transcriptomes of non-model organisms, generating massive amounts of data that enable the study of multiple species in a comparative framework. The sequences generated provide an excellent resource for identifying expressed genes, characterizing functional variation and developing molecular markers, thereby laying the foundations for future studies on gene sequence and gene expression divergence. Here, we report the results of a comparative transcriptome sequencing study of eight individuals representing four Silene and one Dianthus species as outgroup. All sequences and annotations have been deposited in a newly developed and publicly available database called SiESTa, the Silene EST annotation database. Results A total of 1,041,122 EST reads were generated in two runs on a Roche GS-FLX 454 pyrosequencing platform. EST reads were analyzed separately for all eight individuals sequenced and were assembled into contigs using TGICL. These were annotated with results from BLASTX searches and Gene Ontology (GO terms, and thousands of single-nucleotide polymorphisms (SNPs were characterized. Unassembled reads were kept as singletons and together with the contigs contributed to the unigenes characterized in each individual. The high quality of unigenes is evidenced by the proportion (49% that have significant hits in similarity searches with the A. thaliana proteome. The SiESTa database is accessible at http://www.siesta.ethz.ch. Conclusion The sequence collections established in the present study provide an important genomic resource for four Silene and one Dianthus species and will help to

  8. Comparative high-throughput transcriptome sequencing and development of SiESTa, the Silene EST annotation database

    Science.gov (United States)

    2011-01-01

    Background The genus Silene is widely used as a model system for addressing ecological and evolutionary questions in plants, but advances in using the genus as a model system are impeded by the lack of available resources for studying its genome. Massively parallel sequencing cDNA has recently developed into an efficient method for characterizing the transcriptomes of non-model organisms, generating massive amounts of data that enable the study of multiple species in a comparative framework. The sequences generated provide an excellent resource for identifying expressed genes, characterizing functional variation and developing molecular markers, thereby laying the foundations for future studies on gene sequence and gene expression divergence. Here, we report the results of a comparative transcriptome sequencing study of eight individuals representing four Silene and one Dianthus species as outgroup. All sequences and annotations have been deposited in a newly developed and publicly available database called SiESTa, the Silene EST annotation database. Results A total of 1,041,122 EST reads were generated in two runs on a Roche GS-FLX 454 pyrosequencing platform. EST reads were analyzed separately for all eight individuals sequenced and were assembled into contigs using TGICL. These were annotated with results from BLASTX searches and Gene Ontology (GO) terms, and thousands of single-nucleotide polymorphisms (SNPs) were characterized. Unassembled reads were kept as singletons and together with the contigs contributed to the unigenes characterized in each individual. The high quality of unigenes is evidenced by the proportion (49%) that have significant hits in similarity searches with the A. thaliana proteome. The SiESTa database is accessible at http://www.siesta.ethz.ch. Conclusion The sequence collections established in the present study provide an important genomic resource for four Silene and one Dianthus species and will help to further develop Silene as a

  9. An Algorithm for Pedestrian Detection in Multispectral Image Sequences

    Science.gov (United States)

    Kniaz, V. V.; Fedorenko, V. V.

    2017-05-01

    The growing interest for self-driving cars provides a demand for scene understanding and obstacle detection algorithms. One of the most challenging problems in this field is the problem of pedestrian detection. Main difficulties arise from a diverse appearances of pedestrians. Poor visibility conditions such as fog and low light conditions also significantly decrease the quality of pedestrian detection. This paper presents a new optical flow based algorithm BipedDetet that provides robust pedestrian detection on a single-borad computer. The algorithm is based on the idea of simplified Kalman filtering suitable for realization on modern single-board computers. To detect a pedestrian a synthetic optical flow of the scene without pedestrians is generated using slanted-plane model. The estimate of a real optical flow is generated using a multispectral image sequence. The difference of the synthetic optical flow and the real optical flow provides the optical flow induced by pedestrians. The final detection of pedestrians is done by the segmentation of the difference of optical flows. To evaluate the BipedDetect algorithm a multispectral dataset was collected using a mobile robot.

  10. A framework for creating realistic synthetic fluorescence microscopy image sequences

    CSIR Research Space (South Africa)

    Mabaso, M

    2016-02-01

    Full Text Available Fluorescence microscopy imaging is an important tool in modern biological research, allowing insights into the processes of biological systems. Automated image analysis algorithms help in extracting information from these images. Validation...

  11. Fast high-resolution MR imaging using the snapshot-FLASH MR sequence

    International Nuclear Information System (INIS)

    Matthaei, D.; Haase, A.; Henrich, D.; Duhmke, E.

    1990-01-01

    Snapshot, fast low-angle short (FLASH) MR imaging using an accelerated FLASH-MR sequence provides MR images with measuring times far below 1 second. The short TE of this sequence prevents susceptibility artifacts in gradient-echo imaging. In this paper variations of the sequence are shown that provide high resolution images with T1-weighted IR, T2-weighted SE, and chemical shift (CHESS) contrast sequences. METHODS AND MATERIALS: A whole-body 2-T system (Bruker-Medizintechnik) were used in combination with a 60-cm gradient system (providing gradient strength of 5 mT/m) to study healthy volunteers. The measuring time for a 256 x 256 image matrix was 800 msec. This sequence has been used in combination with T1-weighted IR, T2-weighted SE, and CHESS variations

  12. IoSiS: a radar system for imaging of satellites in space

    Science.gov (United States)

    Jirousek, M.; Anger, S.; Dill, S.; Schreiber, E.; Peichl, M.

    2017-05-01

    Space debris nowadays is one of the main threats for satellite systems especially in low earth orbit (LEO). More than 700,000 debris objects with potential to destroy or damage a satellite are estimated. The effects of an impact often are not identifiable directly from ground. High-resolution radar images are helpful in analyzing a possible damage. Therefor DLR is currently developing a radar system called IoSiS (Imaging of Satellites in Space), being based on an existing steering antenna structure and our multi-purpose high-performance radar system GigaRad for experimental investigations. GigaRad is a multi-channel system operating at X band and using a bandwidth of up to 4.4 GHz in the IoSiS configuration, providing fully separated transmit (TX) and receive (RX) channels, and separated antennas. For the observation of small satellites or space debris a highpower traveling-wave-tube amplifier (TWTA) is mounted close to the TX antenna feed. For the experimental phase IoSiS uses a 9 m TX and a 1 m RX antenna mounted on a common steerable positioner. High-resolution radar images are obtained by using Inverse Synthetic Aperture Radar (ISAR) techniques. The guided tracking of known objects during overpass allows here wide azimuth observation angles. Thus high azimuth resolution comparable to the range resolution can be achieved. This paper outlines technical main characteristics of the IoSiS radar system including the basic setup of the antenna, the radar instrument with the RF error correction, and the measurement strategy. Also a short description about a simulation tool for the whole instrument and expected images is shown.

  13. Simulation, image reconstruction and SiPM characterisation for a novel endoscopic positron emission tomography detector

    International Nuclear Information System (INIS)

    Zvolsky, Milan

    2017-12-01

    In the scope of the EndoTOFPET-US project, a novel multimodal device for ultrasound (US) endoscopy and positron emission tomography (PET) is being developed. The project aims at detecting and quantifying morphologic and functional biomarkers and developing new biomarkers for pancreas and prostate oncology. The detector system comprises a small detector probe mounted on an ultrasound endoscope and an external detector plate. The detection of the gamma rays is realised by scintillator crystals with Silicon Photomultiplier (SiPM) read-out. For the characterisation of over 4000 SiPMs for the external plate, an automatised measurement and data analysis procedure is established. The key properties of the SiPMs like breakdown voltage and dark count rate (DCR) are extracted. This knowledge is needed both as a quality assurance as well as for the calibration of the detector. The spread between minimum and maximum breakdown voltage within a SiPM array of 4 x 4 is at maximum 0.43 V with a mean of 0.15 V and an RMS of 0.06 V. This assures the optimal biasing of each SiPM at its individual operating voltage. The mean DCR amounts to 1.49 MHz with an RMS of 0.54 MHz and is thus well below the acceptable threshold of 3 MHz. Two spare modules from the external plate are re-measured and analysed several years after the module assembly, revealing a potential alteration of the SiPM noise properties over time. For the characterisation of SiPMs from different vendors, a software framework for the automatic extraction of performance parameters from pulseheight spectra, including a t of the entire spectrum, is developed and tested. In order to facilitate the modelling of the response of the EndoTOFPET-US detector, a framework is developed which is built around the Geant4-based simulation toolkit GAMOS, to simulate and reconstruct realistic imaging scenarios with this asymmetric PET detector. The simulation studies are used to compare different possible detector designs, guide the

  14. Simulation, image reconstruction and SiPM characterisation for a novel endoscopic positron emission tomography detector

    Energy Technology Data Exchange (ETDEWEB)

    Zvolsky, Milan

    2017-12-15

    In the scope of the EndoTOFPET-US project, a novel multimodal device for ultrasound (US) endoscopy and positron emission tomography (PET) is being developed. The project aims at detecting and quantifying morphologic and functional biomarkers and developing new biomarkers for pancreas and prostate oncology. The detector system comprises a small detector probe mounted on an ultrasound endoscope and an external detector plate. The detection of the gamma rays is realised by scintillator crystals with Silicon Photomultiplier (SiPM) read-out. For the characterisation of over 4000 SiPMs for the external plate, an automatised measurement and data analysis procedure is established. The key properties of the SiPMs like breakdown voltage and dark count rate (DCR) are extracted. This knowledge is needed both as a quality assurance as well as for the calibration of the detector. The spread between minimum and maximum breakdown voltage within a SiPM array of 4 x 4 is at maximum 0.43 V with a mean of 0.15 V and an RMS of 0.06 V. This assures the optimal biasing of each SiPM at its individual operating voltage. The mean DCR amounts to 1.49 MHz with an RMS of 0.54 MHz and is thus well below the acceptable threshold of 3 MHz. Two spare modules from the external plate are re-measured and analysed several years after the module assembly, revealing a potential alteration of the SiPM noise properties over time. For the characterisation of SiPMs from different vendors, a software framework for the automatic extraction of performance parameters from pulseheight spectra, including a t of the entire spectrum, is developed and tested. In order to facilitate the modelling of the response of the EndoTOFPET-US detector, a framework is developed which is built around the Geant4-based simulation toolkit GAMOS, to simulate and reconstruct realistic imaging scenarios with this asymmetric PET detector. The simulation studies are used to compare different possible detector designs, guide the

  15. Three-dimensional imaging for precise structural control of Si quantum dot networks for all-Si solar cells

    Science.gov (United States)

    Kourkoutis, Lena F.; Hao, Xiaojing; Huang, Shujuan; Puthen-Veettil, Binesh; Conibeer, Gavin; Green, Martin A.; Perez-Wurfl, Ivan

    2013-07-01

    All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction.All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to

  16. Enhanced spatio-temporal alignment of plantar pressure image sequences using B-splines.

    Science.gov (United States)

    Oliveira, Francisco P M; Tavares, João Manuel R S

    2013-03-01

    This article presents an enhanced methodology to align plantar pressure image sequences simultaneously in time and space. The temporal alignment of the sequences is accomplished using B-splines in the time modeling, and the spatial alignment can be attained using several geometric transformation models. The methodology was tested on a dataset of 156 real plantar pressure image sequences (3 sequences for each foot of the 26 subjects) that was acquired using a common commercial plate during barefoot walking. In the alignment of image sequences that were synthetically deformed both in time and space, an outstanding accuracy was achieved with the cubic B-splines. This accuracy was significantly better (p align real image sequences with unknown transformation involved, the alignment based on cubic B-splines also achieved superior results than our previous methodology (p alignment on the dynamic center of pressure (COP) displacement was also assessed by computing the intraclass correlation coefficients (ICC) before and after the temporal alignment of the three image sequence trials of each foot of the associated subject at six time instants. The results showed that, generally, the ICCs related to the medio-lateral COP displacement were greater when the sequences were temporally aligned than the ICCs of the original sequences. Based on the experimental findings, one can conclude that the cubic B-splines are a remarkable solution for the temporal alignment of plantar pressure image sequences. These findings also show that the temporal alignment can increase the consistency of the COP displacement on related acquired plantar pressure image sequences.

  17. Real-time UAV trajectory generation using feature points matching between video image sequences

    Science.gov (United States)

    Byun, Younggi; Song, Jeongheon; Han, Dongyeob

    2017-09-01

    Unmanned aerial vehicles (UAVs), equipped with navigation systems and video capability, are currently being deployed for intelligence, reconnaissance and surveillance mission. In this paper, we present a systematic approach for the generation of UAV trajectory using a video image matching system based on SURF (Speeded up Robust Feature) and Preemptive RANSAC (Random Sample Consensus). Video image matching to find matching points is one of the most important steps for the accurate generation of UAV trajectory (sequence of poses in 3D space). We used the SURF algorithm to find the matching points between video image sequences, and removed mismatching by using the Preemptive RANSAC which divides all matching points to outliers and inliers. The inliers are only used to determine the epipolar geometry for estimating the relative pose (rotation and translation) between image sequences. Experimental results from simulated video image sequences showed that our approach has a good potential to be applied to the automatic geo-localization of the UAVs system

  18. MR imaging of the temporomandibular joint. Part 2. Effect of flip angle on MR imaging with FLASH sequence

    International Nuclear Information System (INIS)

    Sakamoto, Maya; Sasano, Takashi; Higano, Shuichi; Takahashi, Shoki; Kurihara, Noriko

    1998-01-01

    In our previous study on MR imaging of the temporomandibular joint (TMJ), fast low angle shot (FLASH) showed the highest image contrast between disc and surrounding TMJ tissues compared with those of 4 other sequences (i,e., fast imaging with steady precession (FISP), conventional T1-weighted spin echo (SE) and fast spin echo (FSE, TR/TE/ETL: 1100/12/3, 3000/15/7)). Furthermore, FLASH also received a high score on visual evaluation including the position and contour of the disc, and the border between the disc and surrounding tissues. Therefore, we concluded that FLASH was the most suitable sequence for evaluating the TMJ disc. However, the image contrast and signal intensity on MR imaging with gradient echo pulse sequence are affected by flip angle. Consequently, in this report, to find the most suitable flip angle for MR scanning of the TMJ using a FLASH sequence (TR/TE: 450/11), ten TMJs of 5 volunteers were experimentally imaged with various flip angles from 10 degrees to 70 degrees at an interval of 10 degrees between 10 to 70. The image contrast and contrast-to-noise ratio (CNR) between the disc and surrounding tissues were compared. In addition, signal-to-noise ratio (SNR) of phantoms was also calculated using the same imaging parameters. Visual evaluation including position and contour of the disc, and the border between the disc and surrounding tissues, was also performed by 4 radiologists. As the flip angle increased, imaging contrast decreased while SNR increased. Images with flip angles between 30 and 60 degrees demonstrated high CNR. On visual evaluation, images using flip angles between 30 and 50 degrees received high scores. In conclusion, FLASH sequence with a flip angle between 30 and 50 degrees was considered most suitable for evaluating the TMJ disc based on the results of visual assessment and analysis of three major components of image diagnostic quality: image contrast, CNR and SNR. (author)

  19. Christian Delporte, Image et politique en France au XXe siècle

    OpenAIRE

    Kéita, Sékouna

    2013-01-01

    Dans cet ouvrage, l’auteur revient sur le rôle de l’image en tant qu’outil de communication mais aussi comme instrument de persuasion et de manipulation politique. Il s’agit d’une réflexion approfondie sur les fonctions politiques des documents visuels (image télévisuelle, cinéma, photographie, dessin et caricature etc.) dans leur évolution à travers le xxe siècle. Une évolution du traitement et du rôle de l’image parallèle aux progrès techniques et technologiques de la société. L’image conna...

  20. MR imaging of articular cartilage in the ankle: comparison of available imaging sequences and methods of measurement in cadavers

    Energy Technology Data Exchange (ETDEWEB)

    Tan, T.C.F. [Department of Radiology, Veterans Administrative Medical Center, San Diego, CA (United States)]|[University of California Medical Center, San Diego, CA (United States)]|[Department of Radiology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan (Taiwan, Province of China); Wilcox, D.M. [Department of Radiology, Veterans Administrative Medical Center, San Diego, CA (United States)]|[University of California Medical Center, San Diego, CA (United States); Frank, L. [Department of Radiology, Veterans Administrative Medical Center, San Diego, CA (United States)]|[University of California Medical Center, San Diego, CA (United States); Shih, C. [Department of Radiology, Veterans Administrative Medical Center, San Diego, CA (United States)]|[University of California Medical Center, San Diego, CA (United States)]|[Department of Radiology, Veterans General Hospital-Taipei (Taiwan, Province of China); Trudell, D.J. [Department of Radiology, Veterans Administrative Medical Center, San Diego, CA (United States)]|[University of California Medical Center, San Diego, CA (United States); Sartoris, D.J. [Department of Radiology, Veterans Administrative Medical Center, San Diego, CA (United States)]|[University of California Medical Center, San Diego, CA (United States); Resnick, D. [Department of Radiology, Veterans Administrative Medical Center, San Diego, CA (United States)]|[University of California Medical Center, San Diego, CA (United States)

    1996-11-01

    Objective. To assess hyaline cartilage of cadaveric ankles using different magnetic resonance (MR) imaging techniques and various methods of measurement. Design and patients. Cartilage thicknesses of the talus and tibia were measured in ten cadaveric ankles by naked eye and by digitized image analysis from MR images of fat-suppressed T1-weighted gradient recalled (FS-SPGR), sequences and pulsed transfer saturation sequences with (FS-STS) and without fat-suppression (STS); these measurements were compared with those derived from direct inspection of cadaveric sections. The accuracy and precision errors were evaluated statistically for each imaging technique as well as measuring method. Contrast-to-noise ratios of cartilage versus joint fluid and marrow were compared for each of the imaging sequences. Results. Statistically, measurements from FS-SPGR images were associated with the smallest estimation error. Precision error of measurements derived from digitized image analysis was found to be smaller than that derived from naked eye measurements. Cartilage thickness measurements in images from STS and FS-STS sequences revealed larger errors in both accuracy and precision. Interobserver variance was larger in naked eye assessment of the cartilage. Contrast-to-noise ratio of cartilage versus joint fluid and marrow was higher with FS-SPGR than with FS-STS or STS sequences. Conclusion. Of the sequences and measurement techniques studied, the FS-SPGR sequence combined with the use of digitized image analysis provides the most accurate method for the assessment of ankle hyaline cartilage. (orig.). With 3 figs., 2 tabs.

  1. MR imaging of articular cartilage in the ankle: comparison of available imaging sequences and methods of measurement in cadavers

    International Nuclear Information System (INIS)

    Tan, T.C.F.; Wilcox, D.M.; Frank, L.; Shih, C.; Trudell, D.J.; Sartoris, D.J.; Resnick, D.

    1996-01-01

    Objective. To assess hyaline cartilage of cadaveric ankles using different magnetic resonance (MR) imaging techniques and various methods of measurement. Design and patients. Cartilage thicknesses of the talus and tibia were measured in ten cadaveric ankles by naked eye and by digitized image analysis from MR images of fat-suppressed T1-weighted gradient recalled (FS-SPGR), sequences and pulsed transfer saturation sequences with (FS-STS) and without fat-suppression (STS); these measurements were compared with those derived from direct inspection of cadaveric sections. The accuracy and precision errors were evaluated statistically for each imaging technique as well as measuring method. Contrast-to-noise ratios of cartilage versus joint fluid and marrow were compared for each of the imaging sequences. Results. Statistically, measurements from FS-SPGR images were associated with the smallest estimation error. Precision error of measurements derived from digitized image analysis was found to be smaller than that derived from naked eye measurements. Cartilage thickness measurements in images from STS and FS-STS sequences revealed larger errors in both accuracy and precision. Interobserver variance was larger in naked eye assessment of the cartilage. Contrast-to-noise ratio of cartilage versus joint fluid and marrow was higher with FS-SPGR than with FS-STS or STS sequences. Conclusion. Of the sequences and measurement techniques studied, the FS-SPGR sequence combined with the use of digitized image analysis provides the most accurate method for the assessment of ankle hyaline cartilage. (orig.). With 3 figs., 2 tabs

  2. Three-dimensional imaging for precise structural control of Si quantum dot networks for all-Si solar cells.

    Science.gov (United States)

    Kourkoutis, Lena F; Hao, Xiaojing; Huang, Shujuan; Puthen-Veettil, Binesh; Conibeer, Gavin; Green, Martin A; Perez-Wurfl, Ivan

    2013-08-21

    All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction.

  3. Presolar SiC Abundances in Primitive Meteorites by NanoSIMS Raster Ion Imaging of Insoluble Organic Matter

    Science.gov (United States)

    Davidson, J.; Busemann, H.; Alexander, C. M. O'd.; Nittler, L. R.; Schrader, D. L.; Orthous-Daunay, F. R.; Quirico, E.; Franchi, I. A.; Grady, M. M.

    2009-03-01

    We present results obtained with NanoSIMS raster ion imaging to determine the abundance of presolar SiC in the insoluble organic matter (IOM) extracted from a number of different classes of chondrites (both carbonaceous and ordinary).

  4. On-board processing of video image sequences

    DEFF Research Database (Denmark)

    Andersen, Jakob Dahl; Chanrion, Olivier Arnaud; Forchhammer, Søren

    2008-01-01

    and evaluated. On-board there are six video cameras each capturing images of 1024times1024 pixels of 12 bpp at a frame rate of 15 fps, thus totalling 1080 Mbits/s. In comparison the average downlink data rate for these images is projected to be 50 kbit/s. This calls for efficient on-board processing to select...

  5. Clinical evaluation of FMPSPGR sequence of the brain MR imaging

    International Nuclear Information System (INIS)

    Takahashi, Mitsuyuki; Hasegawa, Makoto; Mori, Naohiko; Yamanoguchi, Minoru; Matsubara, Tadashi

    1998-01-01

    In order to apply the FMPSPGR (fast multi planar spoiled GRASS) method to diagnose brain diseases, authors obtained the optimal condition for imaging by the phantom experiments and examined the clinical usefulness. Six kinds of the phantom, which were 4 of diluted Gd solution with different concentrations, olive oil and physiological saline solution were used. From the phantom experiments, TR/TE/FR=300/3.3/90 degrees was the optimal condition. The evaluation of the clinical images was performed on the same section by the ST method and the FMPSPGR method. Fifteen patients (9 men and 6 women, aged from 17 to 80 years) suspected of brain diseases were examined, including 8 of cerebral infarction, 1 of pontine infarction, 1 of brain contusion, 1 of intracerebral bleeding and 4 of brain tumors. Four cases of brain tumor were evaluated on the contrast imaging and the others were on the plain imaging. In the plain imaging, the FMPSPGR method was better than the SE method on the low signal region in the T1 weighted imaging. Furthermore, in the contrast imaging, it could give more clear images of the lesion in anterior cranial pit by suppressing artifacts of blood flow. The present results indicate that the FMPSPGR method is useful to diagnose brain diseases. (K.H.)

  6. Image registration based on virtual frame sequence analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.; Ng, W.S. [Nanyang Technological University, Computer Integrated Medical Intervention Laboratory, School of Mechanical and Aerospace Engineering, Singapore (Singapore); Shi, D. (Nanyang Technological University, School of Computer Engineering, Singapore, Singpore); Wee, S.B. [Tan Tock Seng Hospital, Department of General Surgery, Singapore (Singapore)

    2007-08-15

    This paper is to propose a new framework for medical image registration with large nonrigid deformations, which still remains one of the biggest challenges for image fusion and further analysis in many medical applications. Registration problem is formulated as to recover a deformation process with the known initial state and final state. To deal with large nonlinear deformations, virtual frames are proposed to be inserted to model the deformation process. A time parameter is introduced and the deformation between consecutive frames is described with a linear affine transformation. Experiments are conducted with simple geometric deformation as well as complex deformations presented in MRI and ultrasound images. All the deformations are characterized with nonlinearity. The positive results demonstrated the effectiveness of this algorithm. The framework proposed in this paper is feasible to register medical images with large nonlinear deformations and is especially useful for sequential images. (orig.)

  7. Gadolinium-enhanced MR imaging of normal renal transplants. An evaluation of a T1-weighted dynamic echo-planar sequence

    International Nuclear Information System (INIS)

    Dupas, B.; Blancho, G.; Havet, T.; Leaute, F.

    1999-01-01

    Purpose: To evaluate the potential usefulness of dynamic MR with echoplanar imaging (EPI) in assessing the renal function in patients with renal allografts. Material and methods: Using a T1-weighted sequence, EPI was performed after injection of a Gd-chelate in 17 patients with normally functioning renal allografts. Time-intensity curves were plotted from the signal intensity (SI) measurements of the cortex and the medulla. Results: The pattern of corticomedullar differentiation (CMD) observed after constrast enhancement was divided into four phases using the T1-EPI. After a rapid decrease in the SI of cortical structures, and a subsequent return to precontrast levels, a gradual fall in the SI of the medulla was observed. The average time between the two periods of signal loss was 60 s. Conclusion: This study illustrated the potential use of dynamic T1-EPI to demonstrate contrast-induced CMD in renal allografts. (orig.)

  8. MR imaging of the orbit and eye using inversion recovery sequences

    International Nuclear Information System (INIS)

    Smith, F.W.; Parekh, S.; Forrester, J.; Redpath, T.W.

    1986-01-01

    Most centers performing MR imaging use spin-echo sequences to produce images; however, there are many advantages to using short TI inversion-recovery sequences for examination of the orbits. By selecting a TI similar to the relaxation time of any structure, the signal from this can be suppressed, thereby enhancing the signal from other structures. Using a sequence of TR = 1,000 msec and TI of less than 200 msec, the signal from fat is suppressed, improving image quality adjacent to the surface coil and providing better contrast between orbital structures and fat. The use of this short TI sequence for the examination of the eye in patients with opaque lenses is an accurate method of diagnosis since the sequence enhances the signal from both long T1 and T2 lesions. Eighty-five patients with orbital or ocular pathology have been studied, and the results demonstrate the usefulness of this technique for diagnosis

  9. Object analysis of bone marrow MR imaging using double echo STIR sequence in hematological diseases

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, Hitomi [Saitama Medical School, Moroyama (Japan)

    1995-07-01

    The bone marrow of 84 patients with hematological disorders was investigated using short inversion time inversion recovery sequence (STIR) on an 1.5 Tesla superconducting MRI system. Double echo times of 20 and 100 msec were applied to research the signal characteristics of the lesion and carry out quantitative analysis of the receiver operating characteristic curve (ROC). The hematological diseases included 19 cases of myelodysplastic syndrome (MDS), 18 of multiple myeloma (MM), 18 of chronic myelocytic leukemia (CML), 9 of aplastic anemia (AA), 8 of acute myelocytic leukemia (AML), 3 of chronic lymphocytic leukemia (CLL), 3 of myelofibrosis, and 3 others. Using STIR with double echo times, bone marrow showed high signal intensity (SI) on short TE and low SI on long TE in MDS and CML; high SI on short and long TE in myelofibrosis and CLL; high SI on short TE and high to moderately high SI on long TE in MM; and low SI on short and long TE in AA. Quantitative analysis of 33 patients showed high sensitivity and specificity in AA (81% and 94%, respectively) and moderate sensitivity and high specificity in MM (61%, 88%). CML and MDS were similar with low sensitivities (40%, 41%) and high specificities (80%, 78%). Differential diagnosis between CML and MDS was difficult using STIR with the double echo time method. (author).

  10. CT Image Sequence Restoration Based on Sparse and Low-Rank Decomposition

    Science.gov (United States)

    Gou, Shuiping; Wang, Yueyue; Wang, Zhilong; Peng, Yong; Zhang, Xiaopeng; Jiao, Licheng; Wu, Jianshe

    2013-01-01

    Blurry organ boundaries and soft tissue structures present a major challenge in biomedical image restoration. In this paper, we propose a low-rank decomposition-based method for computed tomography (CT) image sequence restoration, where the CT image sequence is decomposed into a sparse component and a low-rank component. A new point spread function of Weiner filter is employed to efficiently remove blur in the sparse component; a wiener filtering with the Gaussian PSF is used to recover the average image of the low-rank component. And then we get the recovered CT image sequence by combining the recovery low-rank image with all recovery sparse image sequence. Our method achieves restoration results with higher contrast, sharper organ boundaries and richer soft tissue structure information, compared with existing CT image restoration methods. The robustness of our method was assessed with numerical experiments using three different low-rank models: Robust Principle Component Analysis (RPCA), Linearized Alternating Direction Method with Adaptive Penalty (LADMAP) and Go Decomposition (GoDec). Experimental results demonstrated that the RPCA model was the most suitable for the small noise CT images whereas the GoDec model was the best for the large noisy CT images. PMID:24023764

  11. Images de la police : deux siècles de fantasmes ?

    Directory of Open Access Journals (Sweden)

    Jean-Marc Berlière

    2009-01-01

    Full Text Available « Il faut que ce que l’on appelle la police soit une chose bien terrible disait plaisamment Madame de... puisque les Anglais aiment mieux les voleurs et que les Turcs aiment mieux la peste ».(S.-R-.N. Chamfort, Maximes, pensées, caractères et anecdotes, 1796.Si le fonctionnaire, le « bureaucrate », le « rond de cuir » et tous les employés de l’administration – « fainéants, payés à ne rien faire, budgétivores », n’ont jamais joui en France -pas plus au XIXe siècle qu’au XXe- d’une image posit...

  12. Evaluation of damage accumulation behavior and strength anisotropy of NITE SiC/SiC composites by acoustic emission, digital image correlation and electrical resistivity monitoring

    International Nuclear Information System (INIS)

    Nozawa, Takashi; Ozawa, Kazumi; Asakura, Yuuki; Kohyama, Akira; Tanigawa, Hiroyasu

    2014-01-01

    Understanding the cracking process of the composites is essential to establish the design basis for practical applications. This study aims to investigate the damage accumulation process and its anisotropy for nano-infiltration transient eutectic sintered (NITE) SiC/SiC composites by various characterization techniques such as the acoustic emission (AE), digital image correlation (DIC) and electrical resistivity (ER) measurements. Cracking behavior below the proportional limit stress (PLS) was specifically addressed. Similar to the other generic SiC/SiC composites, the 1st AE event was identified below the PLS for NITE SiC/SiC composites with a dependency of fabric orientation. The DIC results support that the primary failure mode depending on fiber orientation affected more than the other minor modes did. Detailed AE waveform analysis by wavelet shows a potential to classify the failure behavior depending on architecture. Cracking below the PLS is a potential concern in component deign but the preliminary ER measurements imply that the impact of cracking below the PLS on composite function was limited

  13. A comparative analysis of double inversion recovery TFE and TSE sequences on carotid artery wall imaging

    International Nuclear Information System (INIS)

    Chen Jun; Di Yujin; Bu Chunqing; Zhang Yanfeng; Li Shuhua

    2012-01-01

    Objective: To analyze the characteristics of double inversion recovery (DIR) turbo field echo (TFE) and turbo spin echo (TSE) sequences and explore the value of double inversion recovery TFE sequence on carotid artery wall imaging. Patients and methods: 56 patients (32 males and 24 females, aged 31–76 years with a mean age of 53 years) were performed with DIR TFE and DIR TSE T1 weighted imaging (T1WI) sequences on carotid artery bifurcations. Image quality acquired by different techniques were evaluated and scored by two physicians. Whether there is significant difference is determined by SPSS 11.0 software. Paired-samples t test was used for statistics. Results: There was no significant difference in the image quality scores between two sequences (t = 0.880, P = 0.383 > 0.05). Conclusions: DIR TFE sequence has short scanning time and high spatial resolution. DIR TFE sequence can be used as the preferred sequence for screening carotid atherosclerotic plaque compared with DIR TSE sequence.

  14. Elimination of motion and pulsation artifacts using BLADE sequences in shoulder MR imaging

    International Nuclear Information System (INIS)

    Lavdas, E.; Zaloni, E.; Vlychou, M.; Vassiou, K.; Fezoulidis, I.; Tsagkalis, A.; Dailiana, Z.

    2015-01-01

    To evaluate the ability of proton-density with fat-suppression BLADE (proprietary name for periodically rotated overlapping parallel lines with enhanced reconstruction in MR systems from Siemens Healthcare, PDFS BLADE) and turbo inversion recovery magnitude-BLADE (TIRM BLADE) sequences to reduce motion and pulsation artifacts in shoulder magnetic resonance examinations. Forty-one consecutive patients who had been routinely scanned for shoulder examination participated in the study. The following pairs of sequences with and without BLADE were compared: (a) Oblique coronal proton-density sequence with fat saturation of 25 patients and (b) oblique sagittal T2 TIRM-weighed sequence of 20 patients. Qualitative analysis was performed by two experienced radiologists. Image motion and pulsation artifacts were also evaluated. In oblique coronal PDFS BLADE sequences, motion artifacts have been significantly eliminated, even in five cases of non-diagnostic value with conventional imaging. Similarly, in oblique sagittal T2 TIRM BLADE sequences, image quality has been improved, even in six cases of non-diagnostic value with conventional imaging. Furthermore, flow artifacts have been improved in more than 80% of all the cases. The use of BLADE sequences is recommended in shoulder imaging, especially in uncooperative patients because it effectively eliminates motion and pulsation artifacts. (orig.)

  15. Motion Estimation Using the Firefly Algorithm in Ultrasonic Image Sequence of Soft Tissue

    Directory of Open Access Journals (Sweden)

    Chih-Feng Chao

    2015-01-01

    Full Text Available Ultrasonic image sequence of the soft tissue is widely used in disease diagnosis; however, the speckle noises usually influenced the image quality. These images usually have a low signal-to-noise ratio presentation. The phenomenon gives rise to traditional motion estimation algorithms that are not suitable to measure the motion vectors. In this paper, a new motion estimation algorithm is developed for assessing the velocity field of soft tissue in a sequence of ultrasonic B-mode images. The proposed iterative firefly algorithm (IFA searches for few candidate points to obtain the optimal motion vector, and then compares it to the traditional iterative full search algorithm (IFSA via a series of experiments of in vivo ultrasonic image sequences. The experimental results show that the IFA can assess the vector with better efficiency and almost equal estimation quality compared to the traditional IFSA method.

  16. Research on Image Encryption Based on DNA Sequence and Chaos Theory

    Science.gov (United States)

    Tian Zhang, Tian; Yan, Shan Jun; Gu, Cheng Yan; Ren, Ran; Liao, Kai Xin

    2018-04-01

    Nowadays encryption is a common technique to protect image data from unauthorized access. In recent years, many scientists have proposed various encryption algorithms based on DNA sequence to provide a new idea for the design of image encryption algorithm. Therefore, a new method of image encryption based on DNA computing technology is proposed in this paper, whose original image is encrypted by DNA coding and 1-D logistic chaotic mapping. First, the algorithm uses two modules as the encryption key. The first module uses the real DNA sequence, and the second module is made by one-dimensional logistic chaos mapping. Secondly, the algorithm uses DNA complementary rules to encode original image, and uses the key and DNA computing technology to compute each pixel value of the original image, so as to realize the encryption of the whole image. Simulation results show that the algorithm has good encryption effect and security.

  17. Outdoor Illumination Estimation in Image Sequences for Augmented Reality

    DEFF Research Database (Denmark)

    Madsen, Claus B.; Lal, Brajesh Behari

    2011-01-01

    the detected shadows is used to estimate the radiance of the sun. The technique does not require special purpose objects in the scene, nor does it require High Dynamic Range imagery. Results are demonstrated by rendering augmented objects into real images with shading and shadows which are consistent...

  18. Energy dissipation unveils atomic displacement in the noncontact atomic force microscopy imaging of Si(111 )-(7 ×7 )

    Science.gov (United States)

    Arai, Toyoko; Inamura, Ryo; Kura, Daiki; Tomitori, Masahiko

    2018-03-01

    The kinetic energy of the oscillating cantilever of noncontact atomic force microscopy (nc-AFM) at room temperature was considerably dissipated over regions between a Si adatom and its neighboring rest atom for Si(111 )-(7 ×7 ) in close proximity to a Si tip on the cantilever. However, nc-AFM topographic images showed no atomic features over those regions, which were the hollow sites of the (7 ×7 ). This energy dissipation likely originated from displacement of Si adatoms with respect to the tip over the hollow sites, leading to a lateral shift of the adatoms toward the rest atom. This interaction led to hysteresis over each cantilever oscillation cycle; when the tip was retracted, the Si adatom likely returned to its original position. To confirm the atomic processes involved in the force interactions through Si dangling bonds, the Si(111 )-(7 ×7 ) surface was partly terminated with atomic hydrogen (H) and examined by nc-AFM. When the Si adatoms and/or the rest atoms were terminated with H, the hollow sites were not bright (less dissipation) in images of the energy dissipation channels by nc-AFM. The hollow sites acted as metastable sites for Si adatoms in surface diffusion and atom manipulation; thus, the dissipation energy which is saturated on the tip likely corresponds to the difference in the potential energy between the hollow site and the Si adatom site. In this study, we demonstrated the ability of dissipation channels of nc-AFM to enable visualization of the dynamics of atoms and molecules on surfaces, which cannot be revealed by nc-AFM topographic images alone.

  19. Retrieval of Sentence Sequences for an Image Stream via Coherence Recurrent Convolutional Networks.

    Science.gov (United States)

    Park, Cesc Chunseong; Kim, Youngjin; Kim, Gunhee

    2018-04-01

    We propose an approach for retrieving a sequence of natural sentences for an image stream. Since general users often take a series of pictures on their experiences, much online visual information exists in the form of image streams, for which it would better take into consideration of the whole image stream to produce natural language descriptions. While almost all previous studies have dealt with the relation between a single image and a single natural sentence, our work extends both input and output dimension to a sequence of images and a sequence of sentences. For retrieving a coherent flow of multiple sentences for a photo stream, we propose a multimodal neural architecture called coherence recurrent convolutional network (CRCN), which consists of convolutional neural networks, bidirectional long short-term memory (LSTM) networks, and an entity-based local coherence model. Our approach directly learns from vast user-generated resource of blog posts as text-image parallel training data. We collect more than 22 K unique blog posts with 170 K associated images for the travel topics of NYC, Disneyland , Australia, and Hawaii. We demonstrate that our approach outperforms other state-of-the-art image captioning methods for text sequence generation, using both quantitative measures and user studies via Amazon Mechanical Turk.

  20. In vivo quantitative NMR imaging of fruit tissues during growth using Spoiled Gradient Echo sequence

    DEFF Research Database (Denmark)

    Kenouche, S.; Perrier, M.; Bertin, N.

    2014-01-01

    of this study was to design a robust and accurate quantitative measurement method based on NMR imaging combined with contrast agent (CA) for mapping and quantifying water transport in growing cherry tomato fruits. A multiple flip-angle Spoiled Gradient Echo (SGE) imaging sequence was used to evaluate...

  1. Contrast-enhanced dynamic MR imaging of parasellar tumor using fast spin-echo sequence

    International Nuclear Information System (INIS)

    Kusunoki, Katsusuke; Ohue, Shiro; Ichikawa, Haruhisa; Saito, Masahiro; Sadamoto, Kazuhiko; Sakaki, Saburo; Miki, Hitoshi.

    1995-01-01

    We have applied a new dynamic MRI technique that uses a fast spin-echo sequence to parasellar tumors. This sequence has less susceptible effect and better spatial resolution than a gradient echo sequence, providing faster images than a short spin-echo sequence does. Image was obtained in the coronal or sagittal plane using a 1.5T clinical MRI system, and then, dynamic MR images were acquired every 10 to 20 sec after administration of Gd-DTPA (0.1 mmol/kg). The subjects were 12 patients (5 microadenomas, 5 macroadenomas and 2 Rathke's cleft cysts) and 5 normal volunteers. As for volunteers, the cavernous sinus, pituitary stalk and posterior pituitary gland were contrasted on the first image, followed by visualization of the proximal portion adjacent to the junction of the infundibulum and the anterior pituitary gland, and finally by contrasting the distal portion of the anterior pituitary gland. There was a difference with respect to tumor contrast between microadenomas and macroadenomas. In the case of the macroadenomas, the tumor was contrasted at the same time as, or faster than the anterior pituitary gland, while with the microadenomas the tumor was enhanced later than the anterior pituitary gland. No enhancement with contrast medium was seen in Rathke's cleft cysts. In addition, it was possible to differentiate a recurrent tumor from a piece of muscle placed at surgery since the images obtained by the fast spin-echo sequence were clearer than those obtained by gradient echo sequence. (author)

  2. The role of the STIR sequence in magnetic resonance imaging examination of bone tumours

    International Nuclear Information System (INIS)

    Golfieri, R.; Baddeley, H.; Pringle, J.S.; Souhami, R.

    1990-01-01

    Sixty patients with primary bone tumours were evaluated with magnetic resonance imaging (MRI) at 0.5 T with both conventional spin-echo (SE) and short inversion time inversion recovery (STIR) sequences. The STIR sequence with T 1 of 120-130 ms in all cases suppressed the high signal from fatty bone marrow, giving a clear depiction of tumour extent, in both its intramedullary and soft-tissue components, and is superior to conventional SE images. The high sensitivity (100% of our cases) of this technique is counterbalanced by its lack of specificity: on STIR sequences both tumour and peritumorous oedema give an increase of signal intensity, limiting assessment of tumour extent. Peritumoral oedema, only present in this series in malignant neoplasms, may however be differentiated on the basis of the configuration of the abnormal areas, and by comparing STIR images with short repetition time/echo time sequence results. (author)

  3. Highly-Integrated CMOS Interface Circuits for SiPM-Based PET Imaging Systems.

    Science.gov (United States)

    Dey, Samrat; Lewellen, Thomas K; Miyaoka, Robert S; Rudell, Jacques C

    2012-01-01

    Recent developments in the area of Positron Emission Tomography (PET) detectors using Silicon Photomultipliers (SiPMs) have demonstrated the feasibility of higher resolution PET scanners due to a significant reduction in the detector form factor. The increased detector density requires a proportionally larger number of channels to interface the SiPM array with the backend digital signal processing necessary for eventual image reconstruction. This work presents a CMOS ASIC design for signal reducing readout electronics in support of an 8×8 silicon photomultiplier array. The row/column/diagonal summation circuit significantly reduces the number of required channels, reducing the cost of subsequent digitizing electronics. Current amplifiers are used with a single input from each SiPM cathode. This approach helps to reduce the detector loading, while generating all the necessary row, column and diagonal addressing information. In addition, the single current amplifier used in our Pulse-Positioning architecture facilitates the extraction of pulse timing information. Other components under design at present include a current-mode comparator which enables threshold detection for dark noise current reduction, a transimpedance amplifier and a variable output impedance I/O driver which adapts to a wide range of loading conditions between the ASIC and lines with the off-chip Analog-to-Digital Converters (ADCs).

  4. Dynamic MR imaging of the temporomandibular joint arthrosis using spoiled GRASS sequence

    Energy Technology Data Exchange (ETDEWEB)

    Suenaga, Shigeaki; Hamamoto, Sadatoshi; Kawano, Kazunori (Kagoshima Univ. (Japan). Dental School) (and others)

    1994-07-01

    The purpose of this study was to quantitatively evaluate contrast enhancement effects of the posterior disk attachment in the temporomandibular joint arthrosis using dynamic MRI with bilateral surface coils. One hundred twenty-four temporomandibular joints in 96 symptomatic patients and 27 control subjects were examined with a spoiled GRASS pulse sequence (TR: 35 ms, TE: 8 ms, flip angle: 60deg). One sagittal scan was performed prior to injection, then 0.1 mmol/kg of Gd-DTPA was given as a rapid bolus injection, immediately after which scans were performed at 30 seconds intervals for a period of 5 minutes. Signal intensity (SI) was measured from the ROI of the posterior disk attachment region. The contrast enhancement effects may be calculated by SI ratio (SIR) = ( SI[sup post]-SI[sup pre])/SI[sup pre], where SI[sup post] and SI[sup pre] were the signal intensities after and before administration of contrast medium. The time intensity curve of SIR versus time after injection was obtained on each symptoms. Join pain group (85 joints) tended to show a rapid enhancement pattern, while control group (54 joints), joint sound or opening limitation group (39 joints), and asymptomatic group (68 joints) showed a relatively gradual enhancement pattern. The drop of SIR in four groups were hardly observed during examination. Mean peak SIR of control group, joint pain group, joint sound or opening limitation group, and asymptomatic group was 0.62[+-]0.24 (SD), 1.53[+-]0.69, 0.73[+-]0.38 and 0.78[+-]0.44 respectively. The mean SIR of pain group was significantly (P<0.001, t-test) higher than that of other groups. These results suggested that dynamic MRI of the temporomandibular joint may effectively depict the inflammatory changes of the posterior disk attachment. (author).

  5. Dynamic MR imaging of the temporomandibular joint arthrosis using spoiled GRASS sequence

    International Nuclear Information System (INIS)

    Suenaga, Shigeaki; Hamamoto, Sadatoshi; Kawano, Kazunori

    1994-01-01

    The purpose of this study was to quantitatively evaluate contrast enhancement effects of the posterior disk attachment in the temporomandibular joint arthrosis using dynamic MRI with bilateral surface coils. One hundred twenty-four temporomandibular joints in 96 symptomatic patients and 27 control subjects were examined with a spoiled GRASS pulse sequence (TR: 35 ms, TE: 8 ms, flip angle: 60deg). One sagittal scan was performed prior to injection, then 0.1 mmol/kg of Gd-DTPA was given as a rapid bolus injection, immediately after which scans were performed at 30 seconds intervals for a period of 5 minutes. Signal intensity (SI) was measured from the ROI of the posterior disk attachment region. The contrast enhancement effects may be calculated by SI ratio (SIR) = ( SI post -SI pre )/SI pre , where SI post and SI pre were the signal intensities after and before administration of contrast medium. The time intensity curve of SIR versus time after injection was obtained on each symptoms. Join pain group (85 joints) tended to show a rapid enhancement pattern, while control group (54 joints), joint sound or opening limitation group (39 joints), and asymptomatic group (68 joints) showed a relatively gradual enhancement pattern. The drop of SIR in four groups were hardly observed during examination. Mean peak SIR of control group, joint pain group, joint sound or opening limitation group, and asymptomatic group was 0.62±0.24 (SD), 1.53±0.69, 0.73±0.38 and 0.78±0.44 respectively. The mean SIR of pain group was significantly (P<0.001, t-test) higher than that of other groups. These results suggested that dynamic MRI of the temporomandibular joint may effectively depict the inflammatory changes of the posterior disk attachment. (author)

  6. Optimal pulse-sequence parameters for MR imaging of the immature brain

    International Nuclear Information System (INIS)

    Nowell, M.A.; Hackney, D.B.; Zimmerman, R.A.; Bilaniuk, L.T.; Grossman, R.I.; Goldberg, H.I.

    1986-01-01

    Appropriate spin-echo pulse sequence parameters generate MR images with very high gray matter/white matter contrast in neonates and young infants. Low-contrast images appear to result from utilization of ''adult-type'' parameters to investigate tissues that have relaxation characteristics quite different than those of adult brain. In these young patients long spin-echo sequences with repetition times of 3,000-3,500 msec and multiple echoes with the longest echo time set at 120-160 msec are employed to yield high-contrast ''T2-weighted'' images

  7. Optimal context quantization in lossless compression of image data sequences

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Wu, X.; Andersen, Jakob Dahl

    2004-01-01

    In image compression context-based entropy coding is commonly used. A critical issue to the performance of context-based image coding is how to resolve the conflict of a desire for large templates to model high-order statistic dependency of the pixels and the problem of context dilution due...... to insufficient sample statistics of a given input image. We consider the problem of finding the optimal quantizer Q that quantizes the K-dimensional causal context C/sub t/=(X/sub t-t1/,X/sub t-t2/,...,X/sub t-tK/) of a source symbol X/sub t/ into one of a set of conditioning states. The optimality of context...... quantization is defined to be the minimum static or minimum adaptive code length of given a data set. For a binary source alphabet an optimal context quantizer can be computed exactly by a fast dynamic programming algorithm. Faster approximation solutions are also proposed. In case of m-ary source alphabet...

  8. Estimation of physiological parameters using knowledge-based factor analysis of dynamic nuclear medicine image sequences

    International Nuclear Information System (INIS)

    Yap, J.T.; Chen, C.T.; Cooper, M.

    1995-01-01

    The authors have previously developed a knowledge-based method of factor analysis to analyze dynamic nuclear medicine image sequences. In this paper, the authors analyze dynamic PET cerebral glucose metabolism and neuroreceptor binding studies. These methods have shown the ability to reduce the dimensionality of the data, enhance the image quality of the sequence, and generate meaningful functional images and their corresponding physiological time functions. The new information produced by the factor analysis has now been used to improve the estimation of various physiological parameters. A principal component analysis (PCA) is first performed to identify statistically significant temporal variations and remove the uncorrelated variations (noise) due to Poisson counting statistics. The statistically significant principal components are then used to reconstruct a noise-reduced image sequence as well as provide an initial solution for the factor analysis. Prior knowledge such as the compartmental models or the requirement of positivity and simple structure can be used to constrain the analysis. These constraints are used to rotate the factors to the most physically and physiologically realistic solution. The final result is a small number of time functions (factors) representing the underlying physiological processes and their associated weighting images representing the spatial localization of these functions. Estimation of physiological parameters can then be performed using the noise-reduced image sequence generated from the statistically significant PCs and/or the final factor images and time functions. These results are compared to the parameter estimation using standard methods and the original raw image sequences. Graphical analysis was performed at the pixel level to generate comparable parametric images of the slope and intercept (influx constant and distribution volume)

  9. Comparison of 3 T and 7 T MRI clinical sequences for ankle imaging

    Energy Technology Data Exchange (ETDEWEB)

    Juras, Vladimir, E-mail: vladimir.juras@meduniwien.ac.at [Medical University of Vienna, Department of Radiology, Vienna General Hospital, Waeringer Guertel 18-20, A-1090 Vienna (Austria); Slovak Academy of Sciences, Institute of Measurement Science, Dubravska cesta 9, 84104 Bratislava (Slovakia); Welsch, Goetz, E-mail: welsch@bwh.harvard.edu [Medical University of Vienna, Department of Radiology, Vienna General Hospital, Waeringer Guertel 18-20, A-1090 Vienna (Austria); Baer, Peter, E-mail: baerpeter@siemens.com [Siemens Healthcare, Richard-Strauss-Strasse 76, D81679 Munich (Germany); Kronnerwetter, Claudia, E-mail: claudia.kronnerwetter@meduniwien.ac.at [Medical University of Vienna, Department of Radiology, Vienna General Hospital, Waeringer Guertel 18-20, A-1090 Vienna (Austria); Fujita, Hiroyuki, E-mail: hiroyuki.fujita@qualedyn.com [Quality Electrodynamics, LCC, 777 Beta Dr, Cleveland, OH 44143-2336 (United States); Trattnig, Siegfried, E-mail: siegfried.trattnig@meduniwien.ac.at [Medical University of Vienna, Department of Radiology, Vienna General Hospital, Waeringer Guertel 18-20, A-1090 Vienna (Austria)

    2012-08-15

    The purpose of this study was to compare 3 T and 7 T signal-to-noise and contrast-to noise ratios of clinical sequences for imaging of the ankles with optimized sequences and dedicated coils. Ten healthy volunteers were examined consecutively on both systems with three clinical sequences: (1) 3D gradient-echo, T{sub 1}-weighted; (2) 2D fast spin-echo, PD-weighted; and (3) 2D spin-echo, T{sub 1}-weighted. SNR was calculated for six regions: cartilage; bone; muscle; synovial fluid; Achilles tendon; and Kager's fat-pad. CNR was obtained for cartilage/bone, cartilage/fluid, cartilage/muscle, and muscle/fat-pad, and compared by a one-way ANOVA test for repeated measures. Mean SNR significantly increased at 7 T compared to 3 T for 3D GRE, and 2D TSE was 60.9% and 86.7%, respectively. In contrast, an average SNR decrease of almost 25% was observed in the 2D SE sequence. A CNR increase was observed in 2D TSE images, and in most 3D GRE images. There was a substantial benefit from ultra high-field MR imaging of ankles with routine clinical sequences at 7 T compared to 3 T. Higher SNR and CNR at ultra-high field MR scanners may be useful in clinical practice for ankle imaging. However, carefully optimized protocols and dedicated extremity coils are necessary to obtain optimal results.

  10. Scanning electron-acoustic imaging of residual stress distributions in aluminum metal and ZrSiO4 multiphase ceramics

    International Nuclear Information System (INIS)

    Zhang, B.Y.; Jiang, F.M.; Shi, Y.; Yin, Q.R.; Qian, M.L.

    1997-01-01

    The scanning electron-acoustic imaging technique has been used in the characterization of the residual stress field distributions existing in the subsurface in aluminum disks and 20 vol% SiC ( w)/ZrSiO 4 multiphase ceramics left by Vicker close-quote s indentation. The experimental results reveal that the distribution areas are the plastic-elastic interchange zones. The electron-acoustic signal generation mechanism in the samples are discussed. copyright 1997 American Institute of Physics

  11. MRI investigation of normal fetal lung maturation using signal intensities on different imaging sequences

    International Nuclear Information System (INIS)

    Balassy, Csilla; Kasprian, Gregor; Weber, Michael; Hoermann, Marcus; Prayer, Daniela; Brugger, Peter C.; Csapo, Bence; Mittermayer, Christoph

    2007-01-01

    To purpose of this paper is to study the relation between normal lung maturation signal and changes in intensity ratios (SIR) and to determine which magnetic resonance imaging sequence provides the strongest correlation of normal lung SIs with gestational age. 126 normal singleton pregnancies (20-37 weeks) were examined with a 1.5 Tesla unit. Mean SIs for lungs, liver, and gastric fluid were assessed on six different sequences, and SIRs of lung/liver (LLSIR) and lung/gastric fluid (LGSIR) were correlated with gestational age for each sequence. To evaluate the feasibility of SIRs in the prediction of the state of the lung maturity, accuracy of the predicted SIRs (D*) was measured by calculating relative residuals (D*-D)/D for each sequence. LLSIRs showed significant changes in every sequence (p<0.05), while LGSIRs only on two sequences. Significant differences were shown for the mean of absolute residuals for both LLSIRs (p<0.001) and for LGSIRs (p=0.003). Relative residuals of LLSIRs were significantly smaller on T1-weighted sequence, whereas they were significantly higher for LGSIRs on FLAIR sequence. Fetal liver seems to be adequate reference for the investigation of lung maturation. T1-weighted sequence was the most accurate for the measurement of the lung SIs; thus, we propose to determine LLSIR on T1-weighted sequence when evaluating lung development. (orig.)

  12. MRI investigation of normal fetal lung maturation using signal intensities on different imaging sequences

    Energy Technology Data Exchange (ETDEWEB)

    Balassy, Csilla; Kasprian, Gregor; Weber, Michael; Hoermann, Marcus; Prayer, Daniela [Medical University of Vienna, Department of Radiology, Vienna (Austria); Brugger, Peter C. [Medical University of Vienna, Center of Anatomy and Cell Biology, Vienna (Austria); Csapo, Bence [Medical University of Vienna, Department of Obstetrics and Gyneocology, Vienna (Austria); Mittermayer, Christoph [Medical University of Vienna, Department of Pediatrics, Vienna (Austria)

    2007-03-15

    To purpose of this paper is to study the relation between normal lung maturation signal and changes in intensity ratios (SIR) and to determine which magnetic resonance imaging sequence provides the strongest correlation of normal lung SIs with gestational age. 126 normal singleton pregnancies (20-37 weeks) were examined with a 1.5 Tesla unit. Mean SIs for lungs, liver, and gastric fluid were assessed on six different sequences, and SIRs of lung/liver (LLSIR) and lung/gastric fluid (LGSIR) were correlated with gestational age for each sequence. To evaluate the feasibility of SIRs in the prediction of the state of the lung maturity, accuracy of the predicted SIRs (D*) was measured by calculating relative residuals (D*-D)/D for each sequence. LLSIRs showed significant changes in every sequence (p<0.05), while LGSIRs only on two sequences. Significant differences were shown for the mean of absolute residuals for both LLSIRs (p<0.001) and for LGSIRs (p=0.003). Relative residuals of LLSIRs were significantly smaller on T1-weighted sequence, whereas they were significantly higher for LGSIRs on FLAIR sequence. Fetal liver seems to be adequate reference for the investigation of lung maturation. T1-weighted sequence was the most accurate for the measurement of the lung SIs; thus, we propose to determine LLSIR on T1-weighted sequence when evaluating lung development. (orig.)

  13. Use of the Discrete Cosine Transform for the restoration of an image sequence

    International Nuclear Information System (INIS)

    Acheroy, M.P.J.

    1985-01-01

    The Discrete Cosine Transform (DCT) is recognized as an important tool for image compression techniques. Its use in image restoration is, however, not well known. It is the aim of this paper to provide a restoration method for a sequence of images using the DCT as well for the deblurring as for the noise reduction. It is shown that the DCT can play an interesting role in the deconvolution problem for linear imaging systems with finite, invariant and symmetric impulse response. It is further shown that the noise reduction can be performed onto an image sequence using a time adaptive Kalman filter in the domain of the Karhunen-Loeve transform which is approximated by the DCT

  14. Meteor localization via statistical analysis of spatially temporal fluctuations in image sequences

    Science.gov (United States)

    Kukal, Jaromír.; Klimt, Martin; Šihlík, Jan; Fliegel, Karel

    2015-09-01

    Meteor detection is one of the most important procedures in astronomical imaging. Meteor path in Earth's atmosphere is traditionally reconstructed from double station video observation system generating 2D image sequences. However, the atmospheric turbulence and other factors cause spatially-temporal fluctuations of image background, which makes the localization of meteor path more difficult. Our approach is based on nonlinear preprocessing of image intensity using Box-Cox and logarithmic transform as its particular case. The transformed image sequences are then differentiated along discrete coordinates to obtain statistical description of sky background fluctuations, which can be modeled by multivariate normal distribution. After verification and hypothesis testing, we use the statistical model for outlier detection. Meanwhile the isolated outlier points are ignored, the compact cluster of outliers indicates the presence of meteoroids after ignition.

  15. Fat-saturated diffusion-weighted imaging with three-dimensional MP-RAGE sequence

    International Nuclear Information System (INIS)

    Numano, Tomokazu; Homma, Kazuhiro; Takahashi, Nobuyuki; Hirose, Takeshi

    2005-01-01

    Image misrepresentation due to chemical shifts can create image artifacts on MR images. Distinguishing the organization and affected area can be difficult due to the chemical shift artifacts. Chemical shift selective (CHESS) is a method of decreasing chemical shift artifacts. In this study we have developed a new sequence for fat-saturated three-dimensional diffusion weighted MR imaging. This imaging was done during in vivo studies using an animal experiment MR imaging system at 2.0 T. In this sequence a preparation phase with a ''CHESS-90 deg RF-Motion Proving Gradient (MPG-180 deg RF-MPG-90 deg RF pulse train) was used to sensitize the magnetization to fat-saturated diffusion. Centric k-space acquisition order is necessary to minimize saturation effects from tissues with short relaxation times. From experimental results obtained with a phantom, the effect of the diffusion weighting and the effect of the fat-saturation were confirmed. From rat experimental results, fat-saturated diffusion weighted image data (0.55 x 0.55 x 0.55 mm 3 : voxel size) were obtained. This sequence was useful for in vivo imaging. (author)

  16. Shadow Areas Robust Matching Among Image Sequence in Planetary Landing

    Science.gov (United States)

    Ruoyan, Wei; Xiaogang, Ruan; Naigong, Yu; Xiaoqing, Zhu; Jia, Lin

    2017-01-01

    In this paper, an approach for robust matching shadow areas in autonomous visual navigation and planetary landing is proposed. The approach begins with detecting shadow areas, which are extracted by Maximally Stable Extremal Regions (MSER). Then, an affine normalization algorithm is applied to normalize the areas. Thirdly, a descriptor called Multiple Angles-SIFT (MA-SIFT) that coming from SIFT is proposed, the descriptor can extract more features of an area. Finally, for eliminating the influence of outliers, a method of improved RANSAC based on Skinner Operation Condition is proposed to extract inliers. At last, series of experiments are conducted to test the performance of the approach this paper proposed, the results show that the approach can maintain the matching accuracy at a high level even the differences among the images are obvious with no attitude measurements supplied.

  17. Differential evolution optimization combined with chaotic sequences for image contrast enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Santos Coelho, Leandro dos [Industrial and Systems Engineering Graduate Program, LAS/PPGEPS, Pontifical Catholic University of Parana, PUCPR Imaculada Conceicao, 1155, 80215-901 Curitiba, Parana (Brazil)], E-mail: leandro.coelho@pucpr.br; Sauer, Joao Guilherme [Industrial and Systems Engineering Graduate Program, LAS/PPGEPS, Pontifical Catholic University of Parana, PUCPR Imaculada Conceicao, 1155, 80215-901 Curitiba, Parana (Brazil)], E-mail: joao.sauer@gmail.com; Rudek, Marcelo [Industrial and Systems Engineering Graduate Program, LAS/PPGEPS, Pontifical Catholic University of Parana, PUCPR Imaculada Conceicao, 1155, 80215-901 Curitiba, Parana (Brazil)], E-mail: marcelo.rudek@pucpr.br

    2009-10-15

    Evolutionary Algorithms (EAs) are stochastic and robust meta-heuristics of evolutionary computation field useful to solve optimization problems in image processing applications. Recently, as special mechanism to avoid being trapped in local minimum, the ergodicity property of chaotic sequences has been used in various designs of EAs. Three differential evolution approaches based on chaotic sequences using logistic equation for image enhancement process are proposed in this paper. Differential evolution is a simple yet powerful evolutionary optimization algorithm that has been successfully used in solving continuous problems. The proposed chaotic differential evolution schemes have fast convergence rate but also maintain the diversity of the population so as to escape from local optima. In this paper, the image contrast enhancement is approached as a constrained nonlinear optimization problem. The objective of the proposed chaotic differential evolution schemes is to maximize the fitness criterion in order to enhance the contrast and detail in the image by adapting the parameters using a contrast enhancement technique. The proposed chaotic differential evolution schemes are compared with classical differential evolution to two testing images. Simulation results on three images show that the application of chaotic sequences instead of random sequences is a possible strategy to improve the performance of classical differential evolution optimization algorithm.

  18. Assessment of dosimetrical performance in 11 Varian a-Si500 electronic portal imaging devices

    International Nuclear Information System (INIS)

    Kavuma, Awusi; Glegg, Martin; Currie, Garry; Elliott, Alex

    2008-01-01

    Dosimetrical characteristics of 11 Varian a-Si-500 electronic portal imaging devices (EPIDs) in clinical use for periods ranging between 10 and 86 months were investigated for consistency of performance and portal dosimetry implications. Properties studied include short-term reproducibility, signal linearity with monitor units, response to reference beam, signal uniformity across the detector panel, signal dependence on field size, dose-rate influence, memory effects and image profiles as a function of monitor units. The EPID measurements were also compared with those of the ionization chambers' to ensure stability of the linear accelerators. Depending on their clinical installation date, the EPIDs were interfaced with one of the two different acquisition control software packages, IAS2/IDU-II or IAS3/IDU-20. Both the EPID age and image acquisition system influenced the dosimetric characteristics with the newer version (IAS3 with IDU-20) giving better data reproducibility and linearity fit than the older version (IAS2 with IDU-II). The relative signal response (uniformity) after 50 MU was better than 95% of the central value and independent of detector. Sensitivity for all EPIDs reduced continuously with increasing dose rates for the newer image acquisition software. In the dose-rate range 100-600 MU min -1 , the maximum variation in sensitivity ranged between 1 and 1.8% for different EPIDs. For memory effects, the increase in the measured signal at the centre of the irradiated field for successive images was within 1.8% and 1.0% for the older and newer acquisition systems, respectively. Image profiles acquired at a lower MU in the radial plane (gun-target) had gradients in measured pixel values of up to 25% for the older system. Detectors with software/hardware versions IAS3/IDU-20 have a high degree of accuracy and are more suitable for routine quantitative IMRT dosimetrical verification.

  19. A novel color image encryption scheme using fractional-order hyperchaotic system and DNA sequence operations

    International Nuclear Information System (INIS)

    Zhang Li-Min; Sun Ke-Hui; Liu Wen-Hao; He Shao-Bo

    2017-01-01

    In this paper, Adomian decomposition method (ADM) with high accuracy and fast convergence is introduced to solve the fractional-order piecewise-linear (PWL) hyperchaotic system. Based on the obtained hyperchaotic sequences, a novel color image encryption algorithm is proposed by employing a hybrid model of bidirectional circular permutation and DNA masking. In this scheme, the pixel positions of image are scrambled by circular permutation, and the pixel values are substituted by DNA sequence operations. In the DNA sequence operations, addition and substraction operations are performed according to traditional addition and subtraction in the binary, and two rounds of addition rules are used to encrypt the pixel values. The simulation results and security analysis show that the hyperchaotic map is suitable for image encryption, and the proposed encryption algorithm has good encryption effect and strong key sensitivity. It can resist brute-force attack, statistical attack, differential attack, known-plaintext, and chosen-plaintext attacks. (paper)

  20. Small-target leak detection for a closed vessel via infrared image sequences

    Science.gov (United States)

    Zhao, Ling; Yang, Hongjiu

    2017-03-01

    This paper focus on a leak diagnosis and localization method based on infrared image sequences. Some problems on high probability of false warning and negative affect for marginal information are solved by leak detection. An experimental model is established for leak diagnosis and localization on infrared image sequences. The differential background prediction is presented to eliminate the negative affect of marginal information on test vessel based on a kernel regression method. A pipeline filter based on layering voting is designed to reduce probability of leak point false warning. A synthesize leak diagnosis and localization algorithm is proposed based on infrared image sequences. The effectiveness and potential are shown for developed techniques through experimental results.

  1. Traceable working standards with SI units of radiance for characterizing the measurement performance of investigational clinical NIRF imaging devices

    Science.gov (United States)

    Zhu, Banghe; Rasmussen, John C.; Litorja, Maritoni; Sevick-Muraca, Eva M.

    2017-03-01

    All medical devices for Food and Drug market approval require specifications of performance based upon International System of Units (SI) or units derived from SI for reasons of traceability. Recently, near-infrared fluorescence (NIRF) imaging devices of a variety of designs have emerged on the market and in investigational clinical studies. Yet the design of devices used in the clinical studies vary widely, suggesting variable device performance. Device performance depends upon optimal excitation of NIRF imaging agents, rejection of backscattered excitation and ambient light, and selective collection of fluorescence emanating from the fluorophore. There remains no traceable working standards with SI units of radiance to enable prediction that a given molecular imaging agent can be detected in humans by a given NIRF imaging device. Furthermore, as technologies evolve and as NIRF imaging device components change, there remains no standardized means to track device improvements over time and establish clinical performance without involving clinical trials, often costly. In this study, we deployed a methodology to calibrate luminescent radiance of a stable, solid phantom in SI units of mW/cm2/sr for characterizing the measurement performance of ICCD and IsCMOS camera based NIRF imaging devices, such as signal-to-noise ratio (SNR) and contrast. The methodology allowed determination of superior SNR of the ICCD over the IsCMOS system; comparable contrast of ICCD and IsCMOS depending upon binning strategies.

  2. Parry-Romberg syndrome: findings in advanced magnetic resonance imaging sequences - case report

    Energy Technology Data Exchange (ETDEWEB)

    Paula, Rafael Alfenas de; Ribeiro, Bruno Niemeyer de Freitas, E-mail: alfenas85@gmail.com [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Hospital Universitario Clementino Fraga Filho; Bahia, Paulo Roberto Valle [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Dept. de radiologia; Ribeiro, Renato Niemeyer de Freitas [Hospital de Clinica de Jacarepagua, Rio de Janeiro, RJ (Brazil); Carvalho, Lais Balbi de [Universidade Presidente Antonio Carlos (Unipac), Juiz de Fora, MG (Brazil)

    2014-05-15

    Parry-Romberg syndrome is a rare disease characterized by progressive hemifacial atrophy associated with other systemic changes, including neurological symptoms. Currently, there are few studies exploring the utilization of advanced magnetic resonance sequences in the investigation of this disease. The authors report the case of a 45-year-old patient and describe the findings at structural magnetic resonance imaging and at advanced sequences, correlating them with pathophysiological data. (author)

  3. Artificial Intelligence In Processing A Sequence Of Time-Varying Images

    Science.gov (United States)

    Siler, W.; Tucker, D.; Buckley, J.; Hess, R. G.; Powell, V. G.

    1985-04-01

    A computer system is described for unsupervised analysis of five sets of ultrasound images of the heart. Each set consists of 24 frames taken at 33 millisecond intervals. The images are acquired in real time with computer control of the ultrasound apparatus. After acquisition the images are segmented by a sequence of image-processing programs; features are extracted and stored in a version of the Carnegie- Mellon Blackboard. Region classification is accomplished by a fuzzy logic expert system FLOPS based on OPS5. Preliminary results are given.

  4. Polyetherimide-grafted Fe3O4@SiO2 nanoparticles as theranostic agents for simultaneous VEGF siRNA delivery and magnetic resonance cell imaging

    Directory of Open Access Journals (Sweden)

    Li T

    2015-07-01

    Full Text Available Tingting Li,1 Xue Shen,1 Yin Chen,1 Chengchen Zhang,1 Jie Yan,1 Hong Yang,1 Chunhui Wu,1,2 Hongjun Zeng,1,2 Yiyao Liu1,21Department of Biophysics, School of Life Science and Technology, 2Center for Information in Biomedicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, People’s Republic of ChinaAbstract: Engineering a safe and high-efficiency delivery system for efficient RNA interference is critical for successful gene therapy. In this study, we designed a novel nanocarrier system of polyethyleneimine (PEI-modified Fe3O4@SiO2, which allows high efficient loading of VEGF small hairpin (shRNA to form Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites for VEGF gene silencing as well as magnetic resonance (MR imaging. The size, morphology, particle stability, magnetic properties, and gene-binding capacity and protection were determined. Low cytotoxicity and hemolyticity against human red blood cells showed the excellent biocompatibility of the multifunctional nanocomposites, and also no significant coagulation was observed. The nanocomposites maintain their superparamagnetic property at room temperature and no appreciable change in magnetism, even after PEI modification. The qualitative and quantitative analysis of cellular internalization into MCF-7 human breast cancer cells by Prussian blue staining and inductively coupled plasma atomic emission spectroscopy analysis, respectively, demonstrated that the Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites could be easily internalized by MCF-7 cells, and they exhibited significant inhibition of VEGF gene expression. Furthermore, the MR cellular images showed that the superparamagnetic iron oxide core of our Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites could also act as a T2-weighted contrast agent for cancer MR imaging. Our data highlight multifunctional Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites as a potential platform for simultaneous gene delivery and MR cell imaging, which are promising

  5. Development of an ultrahigh-resolution Si-PM-based dual-head GAGG coincidence imaging system

    Science.gov (United States)

    Yamamoto, Seiichi; Watabe, Hiroshi; Kanai, Yasukazu; Kato, Katsuhiko; Hatazawa, Jun

    2013-03-01

    A silicon photomultiplier (Si-PM) is a promising photodetector for high resolution PET systems due to its small channel size and high gain. Using Si-PMs, it will be possible to develop a high resolution imaging systems. For this purpose, we developed a small field-of-view (FOV) ultrahigh-resolution Si-PM-based dual-head coincidence imaging system for small animals and plant research. A new scintillator, Ce doped Gd3Al12Ga3O12 (GAGG), was selected because of its high light output and its emission wavelength matched with the Si-PM arrays and contained no radioactivity. Each coincidence imaging block detector consists of 0.5×0.5×5 mm3 GAGG pixels combined with a 0.1-mm thick reflector to form a 20×17 matrix that was optically coupled to a Si-PM array (Hamamatsu MPPC S11064-050P) with a 1.5-mm thick light guide. The GAGG block size was 12.0×10.2 mm2. Two GAGG block detectors were positioned face to face and set on a flexible arm based detector stand. All 0.5 mm GAGG pixels in the block detectors were clearly resolved in the 2-dimensional position histogram. The energy resolution was 14.4% FWHM for the Cs-137 gamma ray. The spatial resolution was 0.7 mm FWHM measured using a 0.25 mm diameter Na-22 point source. Small animal and plant images were successfully obtained. We conclude that our developed ultrahigh-resolution Si-PM-based dual-head coincidence imaging system is promising for small animal and plant imaging research.

  6. MR of normal pancreas : comparison of five pulse sequences and enhancing patterns on dynamic imaging

    International Nuclear Information System (INIS)

    Jang, Hyun Jung; Kim, Tae Kyoung; Hong, Sung Hwan; Han, Joon Koo; Choi, Byung Ihn

    1997-01-01

    To compare T1-weighted FLASH and turbo spin echo (SE) T2-weighted sequences with conventional T1- and T2-weighted sequences in imaging normal pancreas and to describe the enhancing patterns on dynamic MR imging. Forty-four patients with presumed hepatic hemangiomas were studied at 1.0T or 1.5T by using conventional SE sequences (T1-weighted, T2-weighted, and heavily T2-weighted), turbo-SE T2-weighted sequences, and breath-hold T1-weighted FLASH sequences acquired before, immediately on, and at 1, 2, 3, and 5 or 10 minutes after injection of a bolus of gadopentetate dimeglumine. No patients had either a history or its clinical features of pancreatic disease. Images were quantitatively analyzed for signal-difference-to noise ratios (SD/Ns) between the pancreas and peripancreatic fat. Percentage enhancement of the pancreas was measured on each dynamic MR image. Conspicuity of the pancreatic border was qualitatively evaluated according to a consensus, reached by three radiologists. Turbo-SE T2-weighted images had a significantly higher SD/N ratio (p<0.001) and better conspicuity of the pancreatic border (p<0.001) than SE T2- and heavily T2-weighted images;T1-weighted SE images had a significantly higher SD/N ratio than T1-weighted FLASH images (p<0.001), but there was no significant difference between tham in qualitative analysis (p=0.346). Percentage enhancement immediately on and at 1, 2, 3, 5, and 10 minutes after administration of contrast material was 39.9%, 44.5%, 42.9%, 40.8%, 36.3%, 29.9%, respectively, with peak enhancement at 1 minute. In MR imaging of normal pancreas, turbo-SE T2-weighted imaging is superior to SE T2- and heavily T2- weighted imaging, and SE T1-weighted imaging is superior to T1-weighted FLASH imaging. On serial gadolinium-enhanced FLASH imaging, normal pancreas shows peak enhancement at 1 minute

  7. Denoising time-resolved microscopy image sequences with singular value thresholding

    Energy Technology Data Exchange (ETDEWEB)

    Furnival, Tom, E-mail: tjof2@cam.ac.uk; Leary, Rowan K., E-mail: rkl26@cam.ac.uk; Midgley, Paul A., E-mail: pam33@cam.ac.uk

    2017-07-15

    Time-resolved imaging in microscopy is important for the direct observation of a range of dynamic processes in both the physical and life sciences. However, the image sequences are often corrupted by noise, either as a result of high frame rates or a need to limit the radiation dose received by the sample. Here we exploit both spatial and temporal correlations using low-rank matrix recovery methods to denoise microscopy image sequences. We also make use of an unbiased risk estimator to address the issue of how much thresholding to apply in a robust and automated manner. The performance of the technique is demonstrated using simulated image sequences, as well as experimental scanning transmission electron microscopy data, where surface adatom motion and nanoparticle structural dynamics are recovered at rates of up to 32 frames per second. - Highlights: • Correlations in space and time are harnessed to denoise microscopy image sequences. • A robust estimator provides automated selection of the denoising parameter. • Motion tracking and automated noise estimation provides a versatile algorithm. • Application to time-resolved STEM enables study of atomic and nanoparticle dynamics.

  8. Characterization of UV-enhanced SiPMs for Imaging in High Pressure Xenon Electroluminescent TPC

    International Nuclear Information System (INIS)

    Yahlali, Nadia; Lorca, David; Fernandes, L.M.P.

    2013-06-01

    The possibility of recording charged particle tracks in an electro-luminescent xenon gas TPC is investigated using a SiPM-based tracking system, operated in the demonstrator prototype of the NEXT-100 ββ decay experiment. The tracks of the ββ0ν events from the decay of the 136 Xe isotope have a distinctive topology, which allows their discrimination against single-electron events from the natural radioactivity that populates the region of interest of the neutrinoless decay in the ββ energy spectrum. Combined to the near-intrinsic energy resolution of the gaseous detector, this tracking capability provides a powerful background rejection tool for the search of the neutrinoless ββ decay aimed by the experiment. The NEXT-100 detector concepts and sensitivity and the first results of its demonstrator prototype are presented. The characterization studies relevant for the operation of UV-enhanced SiPMs used for imaging in an electro-luminescent TPC are reviewed. (authors)

  9. Inter frame motion estimation and its application to image sequence compression: an introduction

    International Nuclear Information System (INIS)

    Cremy, C.

    1996-01-01

    With the constant development of new communication technologies like, digital TV, teleconference, and the development of image analysis applications, there is a growing volume of data to manage. Compression techniques are required for the transmission and storage of these data. Dealing with original images would require the use of expansive high bandwidth communication devices and huge storage media. Image sequence compression can be achieved by means of interframe estimation that consists in retrieving redundant information relative to zones where there is little motion between two frames. This paper is an introduction to some motion estimation techniques like gradient techniques, pel-recursive, block-matching, and its application to image sequence compression. (Author) 17 refs

  10. SR phase contrast imaging to address the evolution of defects during SiC growth

    International Nuclear Information System (INIS)

    Argunova, Tatiana S.; Gutkin, Mikhail Yu.; Je, Jung Ho; Mokhov, Evgeniy N.; Nagalyuk, Sergey S.; Hwu, Yeukuang

    2011-01-01

    Sliced SiC boule grown by physical vapor transport is investigated using synchrotron white beam phase contrast imaging combined with Bragg diffraction. The evolution of defects is revealed. In the early growth stage, foreign polytype inclusions not only induce massive generation of full-core dislocations and dislocated micropipes but also attract them, forming slit-type pores at the boundaries of inclusions. In the intermediate stage, when inclusions stop to grow and become overgrown by the matrix, the pore density significantly reduces, which is attributed to their transformation into new micropipes. In the later stage, the micropipe density decreases, providing evidence for their partial annihilation and healing. Mechanisms for the evolution from inclusions to pores and finally to micropipes during the crystal growth are further discussed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. A six-membered-ring incorporated Si-rhodamine for imaging of copper(ii) in lysosomes.

    Science.gov (United States)

    Wang, Baogang; Cui, Xiaoyan; Zhang, Zhiqiang; Chai, Xiaoyun; Ding, Hao; Wu, Qiuye; Guo, Zhongwu; Wang, Ting

    2016-07-12

    The regulation of copper homeostasis in lysosomes of living cells is closely related to various physiological and pathological processes. Thus, it is of urgent need to develop a fluorescent probe for selectively and sensitively monitoring the location and concentration of lysosomal Cu(2+). Herein, a six-membered ring, thiosemicarbazide, was incorporated into a Si-rhodamine (SiR) scaffold for the first time, affording a SiR-based fluorescent probe SiRB-Cu. Through the effective Cu(2+)-triggered ring-opening process, the probe exhibits fast NIR chromogenic and fluorogenic responses to Cu(2+) within 2 min as the result of formation of a highly fluorescent product SiR-NCS. Compared with a five-membered ring, the expanded ring retains great tolerance to H(+), ensuring the superior sensitivity with a detection limit as low as 7.7 nM and 200-fold enhancement of relative fluorescence in the presence of 1.0 equiv. of Cu(2+) in pH = 5.0 solution, the physiological pH of lysosome. Moreover, the thiosemicarbazide moiety acts not only as the chelating and reactive site, but also as an efficient lysosome-targeting group, leading to the proactive accumulation of the probe into lysosomes. Taking advantage of these distinct properties, SiRB-Cu provides a functional probe suitable for imaging exogenous and endogenous lysosomal Cu(2+) with high imaging contrast and fidelity.

  12. Cardiac tumors: optimal cardiac MR sequences and spectrum of imaging appearances.

    LENUS (Irish Health Repository)

    O'Donnell, David H

    2012-02-01

    OBJECTIVE: This article reviews the optimal cardiac MRI sequences for and the spectrum of imaging appearances of cardiac tumors. CONCLUSION: Recent technologic advances in cardiac MRI have resulted in the rapid acquisition of images of the heart with high spatial and temporal resolution and excellent myocardial tissue characterization. Cardiac MRI provides optimal assessment of the location, functional characteristics, and soft-tissue features of cardiac tumors, allowing accurate differentiation of benign and malignant lesions.

  13. Rapid 3D Reconstruction for Image Sequence Acquired from UAV Camera

    Directory of Open Access Journals (Sweden)

    Yufu Qu

    2018-01-01

    Full Text Available In order to reconstruct three-dimensional (3D structures from an image sequence captured by unmanned aerial vehicles’ camera (UAVs and improve the processing speed, we propose a rapid 3D reconstruction method that is based on an image queue, considering the continuity and relevance of UAV camera images. The proposed approach first compresses the feature points of each image into three principal component points by using the principal component analysis method. In order to select the key images suitable for 3D reconstruction, the principal component points are used to estimate the interrelationships between images. Second, these key images are inserted into a fixed-length image queue. The positions and orientations of the images are calculated, and the 3D coordinates of the feature points are estimated using weighted bundle adjustment. With this structural information, the depth maps of these images can be calculated. Next, we update the image queue by deleting some of the old images and inserting some new images into the queue, and a structural calculation of all the images can be performed by repeating the previous steps. Finally, a dense 3D point cloud can be obtained using the depth–map fusion method. The experimental results indicate that when the texture of the images is complex and the number of images exceeds 100, the proposed method can improve the calculation speed by more than a factor of four with almost no loss of precision. Furthermore, as the number of images increases, the improvement in the calculation speed will become more noticeable.

  14. Rapid 3D Reconstruction for Image Sequence Acquired from UAV Camera.

    Science.gov (United States)

    Qu, Yufu; Huang, Jianyu; Zhang, Xuan

    2018-01-14

    In order to reconstruct three-dimensional (3D) structures from an image sequence captured by unmanned aerial vehicles' camera (UAVs) and improve the processing speed, we propose a rapid 3D reconstruction method that is based on an image queue, considering the continuity and relevance of UAV camera images. The proposed approach first compresses the feature points of each image into three principal component points by using the principal component analysis method. In order to select the key images suitable for 3D reconstruction, the principal component points are used to estimate the interrelationships between images. Second, these key images are inserted into a fixed-length image queue. The positions and orientations of the images are calculated, and the 3D coordinates of the feature points are estimated using weighted bundle adjustment. With this structural information, the depth maps of these images can be calculated. Next, we update the image queue by deleting some of the old images and inserting some new images into the queue, and a structural calculation of all the images can be performed by repeating the previous steps. Finally, a dense 3D point cloud can be obtained using the depth-map fusion method. The experimental results indicate that when the texture of the images is complex and the number of images exceeds 100, the proposed method can improve the calculation speed by more than a factor of four with almost no loss of precision. Furthermore, as the number of images increases, the improvement in the calculation speed will become more noticeable.

  15. Preparation of Microkernel-Based Mesoporous (SiO2-CdTe-SiO2)@SiO2 Fluorescent Nanoparticles for Imaging Screening and Enrichment of Heat Shock Protein 90 Inhibitors from Tripterygium Wilfordii.

    Science.gov (United States)

    Hu, Yue; Miao, Zhao-Yi; Zhang, Xiao-Jing; Yang, Xiao-Tong; Tang, Ying-Ying; Yu, Sheng; Shan, Chen-Xiao; Wen, Hong-Mei; Zhu, Dong

    2018-05-01

    The currently utilized ligand fishing for bioactive molecular screening from complex matrixes cannot perform imaging screening. Here, we developed a new solid-phase ligand fishing coupled with an in situ imaging protocol for the specific enrichment and identification of heat shock protein 90 (Hsp 90) inhibitors from Tripterygium wilfordii, utilizing a multiple-layer and microkernel-based mesoporous nanostructure composed of a protective silica coating CdTe quantum dot (QD) core and a mesoporous silica shell, i.e., microkernel-based mesoporous (SiO 2 -CdTe-SiO 2 )@SiO 2 fluorescent nanoparticles (MMFNPs) as extracting carries and fluorescent probes. The prepared MMFNPs showed a highly uniform spherical morphology, retention of fluorescence emission, and great chemical stability. The fished ligands by Hsp 90α-MMFNPs were evaluated via the preliminary bioactivity based on real-time cellular morphology imaging by confocal laser scanning microscopy (CLSM) and then identified by mass spectrometry (MS). Celastrol was successfully isolated as an Hsp 90 inhibitor, and two other specific components screened by Hsp 90α-MMFNPs, i.e., demecolcine and wilforine, were preliminarily identified as potential Hsp 90 inhibitors through the verification of strong affinity to Hsp 90 and antitumor bioactivity. The approach based on the MMFNPs provides a strong platform for imaging screening and discovery of plant-derived biologically active molecules with high efficiency and selectivity.

  16. Limited-sequence magnetic resonance imaging in the evaluation of the ultrasonographically indeterminate pelvic mass

    Energy Technology Data Exchange (ETDEWEB)

    Chang, S.D. [Univ. of British Columbia, Vancouver Hospital and Helath Services Centre, Dept. of Radiology, Vancouver, British Columbia (Canada)]. E-mail: schang@vanhosp.bc.ca; Cooperberg, P.L.; Wong, A.D. [Univ. of British Columbia, St. Paul' s Hospital, Dept. of Radiology, Vancouver, British Columbia (Canada); Llewellyn, P.A. [Lion' s Gate Hospital, Dept. of Radiology, North Vancouver, British Columbia (Canada); Bilbey, J.H. [Royal Inland Hospital, Dept. of Radiology, Kamloops, British Columbia (Canada)

    2004-04-01

    To evaluate the usefulness of limited-sequence magnetic resonance imaging (MRI) in the elucidation of ultrasonographically indeterminate pelvic masses. This study focused only on pelvic masses in which the origin of the mass (uterine v. extrauterine) could not be determined by ultrasonography (US). The origin of a pelvic mass has clinical implications. A mass arising from the uterus is most likely to be a leiomyoma, which is a benign lesion, whereas an extrauterine mass will have a higher likelihood of malignancy and usually requires surgery. Eighty-one female patients whose pelvic mass was of indeterminate origin on US also underwent limited-sequence MRI of the pelvis. Most of the MRI examinations were performed on the same day as the US. Limited-sequence MRI sequences included a quick gradient-echoT{sub 1}-weighted localizer and a fast spin-echoT{sub 2}-weighted sequence. Final diagnoses were established by surgical pathology or by clinical and imaging follow-up. Limited-sequence MRI was helpful in 79 of the 81 cases (98%). Fifty-two of the 81 masses (64%) were leiomyomas. One was a leiomyosarcoma. The extrauterine masses (26/81 [32%]) were identified as 14 ovarian malignancies, 4 endometriomas, 3 dermoids, an ovarian fibroma, an infarcted fibrothecoma, an infarcted hemorrhagic cyst, a sigmoid diverticular abscess and a gastrointestinal stromal tumour of the ileum. In the other 2 cases (2/81 [2%]), the origin of the pelvic mass remained indeterminate. Both of these indeterminate masses showed low signal onT{sub 2}-weighted images and were interpreted as probable leiomyomas. They were not surgically removed but were followed clinically and had a stable course. Limited-sequence MRI is a quick and efficient way to further evaluate ultrasonographically indeterminate pelvic masses. Limited-sequence MRI of the pelvis can suffice, in these cases, without requiring a full MRI examination. (author)

  17. Limited-sequence magnetic resonance imaging in the evaluation of the ultrasonographically indeterminate pelvic mass

    International Nuclear Information System (INIS)

    Chang, S.D.; Cooperberg, P.L.; Wong, A.D.; Llewellyn, P.A.; Bilbey, J.H.

    2004-01-01

    To evaluate the usefulness of limited-sequence magnetic resonance imaging (MRI) in the elucidation of ultrasonographically indeterminate pelvic masses. This study focused only on pelvic masses in which the origin of the mass (uterine v. extrauterine) could not be determined by ultrasonography (US). The origin of a pelvic mass has clinical implications. A mass arising from the uterus is most likely to be a leiomyoma, which is a benign lesion, whereas an extrauterine mass will have a higher likelihood of malignancy and usually requires surgery. Eighty-one female patients whose pelvic mass was of indeterminate origin on US also underwent limited-sequence MRI of the pelvis. Most of the MRI examinations were performed on the same day as the US. Limited-sequence MRI sequences included a quick gradient-echoT 1 -weighted localizer and a fast spin-echoT 2 -weighted sequence. Final diagnoses were established by surgical pathology or by clinical and imaging follow-up. Limited-sequence MRI was helpful in 79 of the 81 cases (98%). Fifty-two of the 81 masses (64%) were leiomyomas. One was a leiomyosarcoma. The extrauterine masses (26/81 [32%]) were identified as 14 ovarian malignancies, 4 endometriomas, 3 dermoids, an ovarian fibroma, an infarcted fibrothecoma, an infarcted hemorrhagic cyst, a sigmoid diverticular abscess and a gastrointestinal stromal tumour of the ileum. In the other 2 cases (2/81 [2%]), the origin of the pelvic mass remained indeterminate. Both of these indeterminate masses showed low signal onT 2 -weighted images and were interpreted as probable leiomyomas. They were not surgically removed but were followed clinically and had a stable course. Limited-sequence MRI is a quick and efficient way to further evaluate ultrasonographically indeterminate pelvic masses. Limited-sequence MRI of the pelvis can suffice, in these cases, without requiring a full MRI examination. (author)

  18. Retrospective comparison of three-dimensional imaging sequences in the visualization of posterior fossa cranial nerves.

    Science.gov (United States)

    Ors, Suna; Inci, Ercan; Turkay, Rustu; Kokurcan, Atilla; Hocaoglu, Elif

    2017-12-01

    To compare efficancy of three-dimentional SPACE (sampling perfection with application-optimized contrasts using different flip-angle evolutions) and CISS (constructive interference in steady state) sequences in the imaging of the cisternal segments of cranial nerves V-XII. Temporal MRI scans from 50 patients (F:M ratio, 27:23; mean age, 44.5±15.9 years) admitted to our hospital with vertigo, tinnitus, and hearing loss were retrospectively analyzed. All patients had both CISS and SPACE sequences. Quantitative analysis of SPACE and CISS sequences was performed by measuring the ventricle-to-parenchyma contrast-to-noise ratio (CNR). Qualitative analysis of differences in visualization capability, image quality, and severity of artifacts was also conducted. A score ranging 'no artefact' to 'severe artefacts and unreadable' was used for the assessment of artifacts and from 'not visualized' to 'completely visualized' for the assesment of image quality, respectively. The distribution of variables was controlled by the Kolmogorov-Smirnov test. Samples t-test and McNemar's test were used to determine statistical significance. Rates of visualization of posterior fossa cranial nerves in cases of complete visualization were as follows: nerve V (100% for both sequences), nerve VI (94% in SPACE, 86% in CISS sequences), nerves VII-VIII (100% for both sequences), IX-XI nerve complex (96%, 88%); nerve XII (58%, 46%) (p<0.05). SPACE sequences showed fewer artifacts than CISS sequences (p<0.002). Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Prostate cancer in magnetic resonance imaging: diagnostic utilites of spectroscopic sequences

    International Nuclear Information System (INIS)

    Caivano, Rocchina; Cirillo, Patrizia; Lotumolo, Antonella; Fortunato, Giovanna; Zandolino, Alexis; Cammarota, Aldo; Balestra, Antonio; Macarini, Luca; Vita, Giulia

    2012-01-01

    The aim of our work is to determine the efficacy of a combined study 3 Tesla Magnetic Resonance Imaging (3T MRI), with phased-array coil, for the detection of prostate cancer using magnetic resonance spectroscopy (MRS) and diffusion-weighted images (DWI) in identifying doubt nodules. In this study, we prospectively studied 46 patients who consecutively underwent digital-rectal exploration for high doses of prostate specific antigen (PSA), as well as a MRI examination and a subsequent rectal biopsy. The study of magnetic resonance imaging was performed with a Philips Achieva 3T scanner and phased-array coil. The images were obtained with turbo spin-echo sequences T2-weighted images, T1-weighted before and after the administration of contrast medium, DWI sequences and 3D spectroscopic sequences. The ultrasound-guided prostate biopsy was performed approximately 15 days after the MRI. The data obtained from MR images and spectroscopy were correlated with histological data. MRI revealed sensitivity and specificity of 88% and 61% respectively and positive predictive value (PPV) of 73%, negative predicted value (NPV) of 81% and accuracy of 76%. In identifying the location of prostate cancer, the sensitivity of 3T MRS was 92%, with a specificity of 89%, PPV of 87%, NPV of 88% and accuracy of 87%; DWI showed a sensitivity of 88%, specificity of 61%, PPV of 73%, NPV of 81% and accuracy of 76%. The 3T MR study with phased-array coil and the use of DWI and spectroscopic sequences, in addition to T2-weighted sequences, revealed to be accurate in the diagnosis of prostate cancer and in the identification of nodules to be biopsied. It may be indicated as a resolute way before biopsy in patients with elevated PSA value and can be proposed in the staging and follow-up.

  20. Frequency-locked pulse sequencer for high-frame-rate monochromatic tissue motion imaging.

    Science.gov (United States)

    Azar, Reza Zahiri; Baghani, Ali; Salcudean, Septimiu E; Rohling, Robert

    2011-04-01

    To overcome the inherent low frame rate of conventional ultrasound, we have previously presented a system that can be implemented on conventional ultrasound scanners for high-frame-rate imaging of monochromatic tissue motion. The system employs a sector subdivision technique in the sequencer to increase the acquisition rate. To eliminate the delays introduced during data acquisition, a motion phase correction algorithm has also been introduced to create in-phase displacement images. Previous experimental results from tissue- mimicking phantoms showed that the system can achieve effective frame rates of up to a few kilohertz on conventional ultrasound systems. In this short communication, we present a new pulse sequencing strategy that facilitates high-frame-rate imaging of monochromatic motion such that the acquired echo signals are inherently in-phase. The sequencer uses the knowledge of the excitation frequency to synchronize the acquisition of the entire imaging plane to that of an external exciter. This sequencing approach eliminates any need for synchronization or phase correction and has applications in tissue elastography, which we demonstrate with tissue-mimicking phantoms. © 2011 IEEE

  1. No Reference Prediction of Quality Metrics for H.264 Compressed Infrared Image Sequences for UAV Applications

    DEFF Research Database (Denmark)

    Hossain, Kabir; Mantel, Claire; Forchhammer, Søren

    2018-01-01

    The framework for this research work is the acquisition of Infrared (IR) images from Unmanned Aerial Vehicles (UAV). In this paper we consider the No-Reference (NR) prediction of Full Reference Quality Metrics for Infrared (IR) video sequences which are compressed and thus distorted by an H.264...

  2. A generative Bezier curve model for surf-zone tracking in coastal image sequences

    CSIR Research Space (South Africa)

    Burke, Michael G

    2017-09-01

    Full Text Available This work introduces a generative Bezier curve model suitable for surf-zone curve tracking in coastal image sequences. The model combines an adaptive curve parametrised by control points governed by local random walks with a global sinusoidal motion...

  3. Diffusion tensor imaging. Theory, sequence optimization and application in Alzheimer's disease

    International Nuclear Information System (INIS)

    Stieltjes, B.; Schlueter, M.; Hahn, H.K.; Wilhelm, T.; Essig, M.

    2003-01-01

    Diffusion tensor imaging (DTI) offers an in vivo view into the microarchitecture of the brain. Furthermore it allows a three-dimensional reconstruction of fiber tracts. We will discuss the principles of DTI and possibilities for sequence optimization. Finally we will give an overview of DTI and its application in Alzheimer's disease. (orig.) [de

  4. PETRA, MSVAT-SPACE and SEMAC sequences for metal artefact reduction in dental MR imaging

    International Nuclear Information System (INIS)

    Hilgenfeld, Tim; Heil, Alexander; Bendszus, Martin; Prager, Marcel; Heiland, Sabine; Schwindling, Franz Sebastian; Rammelsberg, Peter; Nittka, Mathias; Grodzki, David

    2017-01-01

    Dental MRI is often impaired by artefacts due to metallic dental materials. Several sequences were developed to reduce susceptibility artefacts. Here, we evaluated a set of sequences for artefact reduction for dental MRI for the first time. Artefact volume, signal-to-noise ratio (SNR) and image quality were assessed on a 3-T MRI for pointwise encoding time reduction with radial acquisition (PETRA), multiple-slab acquisition with view angle tilting gradient, based on a sampling perfection with application-optimised contrasts using different flip angle evolution (SPACE) sequence (MSVAT-SPACE), slice-encoding for metal-artefact correction (SEMAC) and compared to a standard SPACE and a standard turbo-spin-echo (TSE) sequence. Field-of-view and acquisition times were chosen to enable in vivo application. Two implant-supported prostheses were tested (porcelain fused to metal non-precious alloy and monolithic zirconia). Smallest artefact was measured for TSE sequences with no difference between the standard TSE and the SEMAC. MSVAT-SPACE reduced artefacts about 56% compared to the standard SPACE. Effect of the PETRA was dependent on sample used. Image quality and SNR were comparable for all sequences except PETRA, which yielded poor results. There is no benefit in terms of artefact reduction for SEMAC compared to standard TSE. Usage of MSVAT-SPACE is advantageous since artefacts are reduced and higher resolution is achieved. (orig.)

  5. PETRA, MSVAT-SPACE and SEMAC sequences for metal artefact reduction in dental MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hilgenfeld, Tim; Heil, Alexander; Bendszus, Martin [Heidelberg University Hospital, Department of Neuroradiology, Heidelberg (Germany); Prager, Marcel; Heiland, Sabine [Heidelberg University Hospital, Department of Neuroradiology, Heidelberg (Germany); Heidelberg University Hospital, Section of Experimental Radiology, Heidelberg (Germany); Schwindling, Franz Sebastian; Rammelsberg, Peter [Heidelberg University Hospital, Department of Prosthodontics, Heidelberg (Germany); Nittka, Mathias; Grodzki, David [Siemens Healthcare GmbH, Erlangen (Germany)

    2017-12-15

    Dental MRI is often impaired by artefacts due to metallic dental materials. Several sequences were developed to reduce susceptibility artefacts. Here, we evaluated a set of sequences for artefact reduction for dental MRI for the first time. Artefact volume, signal-to-noise ratio (SNR) and image quality were assessed on a 3-T MRI for pointwise encoding time reduction with radial acquisition (PETRA), multiple-slab acquisition with view angle tilting gradient, based on a sampling perfection with application-optimised contrasts using different flip angle evolution (SPACE) sequence (MSVAT-SPACE), slice-encoding for metal-artefact correction (SEMAC) and compared to a standard SPACE and a standard turbo-spin-echo (TSE) sequence. Field-of-view and acquisition times were chosen to enable in vivo application. Two implant-supported prostheses were tested (porcelain fused to metal non-precious alloy and monolithic zirconia). Smallest artefact was measured for TSE sequences with no difference between the standard TSE and the SEMAC. MSVAT-SPACE reduced artefacts about 56% compared to the standard SPACE. Effect of the PETRA was dependent on sample used. Image quality and SNR were comparable for all sequences except PETRA, which yielded poor results. There is no benefit in terms of artefact reduction for SEMAC compared to standard TSE. Usage of MSVAT-SPACE is advantageous since artefacts are reduced and higher resolution is achieved. (orig.)

  6. Optimal pulse sequence for ferumoxides-enhanced MR imaging used in the detection of hepatocellular carcinoma: a comparative study using seven pulse sequences

    International Nuclear Information System (INIS)

    Kim, Seung Hoon; Choi, Dongil; Lim, Jae Hoon; Lee, Won Jae; Jang, Hyun Jung; Lim, Kyo Keun; Lee, Soon Jin; Cho, Jae Min; Kim, Seung Kwon; Kim, Gab Chul

    2002-01-01

    To identify the optimal pulse sequence for ferumoxides-enhanced magnetic resonance (MR) imaging in the detection of hepatocelluar carcinomas (HCCs). Sixteen patients with 25 HCCs underwent MR imaging following intravenous infusion of ferumoxides. All MR studies were performed on a 1.5-T MR system, using a phased-array coil. Ferumoxides (Feridex IV) at a dose of 15 μmol/Kg was slowly infused intravenously, and axial images of seven sequences were obtained 30 minutes after the end of infusion. The MR protocol included fast spin-echo (FSE) with two echo times (TR3333-8571/TE18 and 90-117), singleshot FSE (SSFSE) with two echo times (TR∞/TE39 and 98), T2-weighted gradient-recalled acquisition in the steady state (GRASS) (TR216/TE20), T2-weighted fast multiplanar GRASS (FMPGR) (TR130/TE8.4-9.5), and T2-weighted fast multiplanar spoiled GRASS (FMPSPGR) (TR130/TE8.4-9.5). Contrast-to-noise ratios (CNRs) of HCCs determined during the imaging sequences formed the basis of quantitative analysis, and images were qualitatively assessed in terms of lesion conspicuity and image artifacts. The diagnostic accuracy of all sequences was assessed using receiver operating characteristic (ROC) analysis. Quantitative analysis revealed that the CNRs of T2-weighted FMPGR and T2-weighted FMPSPGR were significantly higher than those of the other sequences, while qualitative analysis showed that image artifacts were prominent at T2-weighted GRASS imaging. Lesion conspicuity was statistically significantly less clear at SSFSE imaging. In term of lesion detection, T-weighted FMPGR, T2- weighted FMPSPGR, and proton density FSE imaging were statistically superior to the others. T2-weighted FMPGR, T2- weighted FMPSPGR, and proton density FSE appear to be the optimal pulse sequences for ferumoxidesenhanced MR imaging in the detection of HCCs

  7. Surface coil imaging of the spine using fast sequences: Improvement of intensity profile and contrast behavior

    International Nuclear Information System (INIS)

    Requardt, H.; Deimling, M.; Weber, H.

    1986-01-01

    Sagittal and axial images obtained using a surface coil suffer from the extreme intensity profile caused by physical properties of the coil and the anatomic entity of subcutaneous fat. The authors present a measuring device that reduces these disadvantages by means of Helmholtz-type coils, and sequences that reduce the fat signal by dephasing its signal part. The extremely short repetition time (<30 msec) allows acquisition times shorter than 10 sec. Breath-holding for this short period to avoid movement artifacts is possible. Images are presented that illustrate the enhanced contrast of spinal tissue and surrounding structures. Comparisons are made with spin-echo and CHESS images

  8. Water imaging (hydrography) in the fetus: the value of a heavily T2-weighted sequence

    Energy Technology Data Exchange (ETDEWEB)

    Kline-Fath, Beth M.; Calvo-Garcia, Maria A.; O' Hara, Sara M.; Racadio, Judy M. [University of Cincinnati Medical Center, Department of Radiology, Cincinnati Children' s Hospital Medical Center, Cincinnati, OH (United States)

    2007-02-15

    Since the development of fast imaging sequences, MR has proved to be a helpful tool in the evaluation of fetal pathology. Because of the high water content of fetal tissues and pathology, hydrography imaging (MR fetography) can provide additional diagnostic information. To demonstrate the benefit of MR fetography in fetal imaging. From 2004 to 2005, 126 fetal MR examinations were performed for evaluation of an abnormality depicted on an antenatal sonogram. Single-shot fast spin-echo MR imaging and MR fetography were performed through the area of fetal pathology. The two studies were retrospectively compared. The primary diagnosis was not changed with the addition of MR fetography. New findings, particularly in the kidneys and spine, were identified in 9% of the patients. When fetal pathology was of high water content (80% patients), the MR fetography imaging increased diagnostic confidence. In 11% of the patients, those with cardiovascular or low water pathology, the MR fetography was not beneficial. The mainstay of fetal imaging is currently the HASTE and SSFSE sequences. However, MR fetography is an excellent adjunct that highlights fetal pathology by reinforcing the diagnosis, identifying additional findings, and providing high-contrast high-resolution images that are helpful when counseling clinicians and patients. (orig.)

  9. Common crus aplasia: diagnosis by 3D volume rendering imaging using 3DFT-CISS sequence

    International Nuclear Information System (INIS)

    Kim, H.J.; Song, J.W.; Chon, K.-M.; Goh, E.-K.

    2004-01-01

    AIM: The purpose of this study was to evaluate the findings of three-dimensional (3D) volume rendering (VR) imaging in common crus aplasia (CCA) of the inner ear. MATERIALS AND METHODS: Using 3D VR imaging of temporal bone constructive interference in steady state (CISS) magnetic resonance (MR) images, we retrospectively reviewed seven inner ears of six children who were candidates for cochlear implants and who had been diagnosed with CCA. As controls, we used the same method to examine 402 inner ears of 201 patients who had no clinical symptoms or signs of sensorineural hearing loss. Temporal bone MR imaging (MRI) was performed with a 1.5 T MR machine using a CISS sequence, and VR of the inner ear was performed on a work station. Morphological image analysis was performed on rotation views of 3D VR images. RESULTS: In all seven cases, CCA was diagnosed by the absence of the common crus. The remaining superior semicircular canal (SCC) was normal in five and hypoplastic in two inner ears, while the posterior SCC was normal in all seven. One patient showed bilateral symmetrical CCA. Complicated combined anomalies were seen in the cochlea, vestibule and lateral SCC. CONCLUSION: 3D VR imaging findings with MR CISS sequence can directly diagnose CCA. This technique may be useful in delineating detailed anomalies of SCCs

  10. Quantitative hard x-ray phase contrast imaging of micropipes in SiC

    International Nuclear Information System (INIS)

    Kohn, V. G.; Argunova, T. S.; Je, J. H.

    2013-01-01

    Peculiarities of quantitative hard x-ray phase contrast imaging of micropipes in SiC are discussed. The micropipe is assumed as a hollow cylinder with an elliptical cross section. The major and minor diameters can be restored using the least square fitting procedure by comparing the experimental data, i.e. the profile across the micropipe axis, with those calculated based on phase contrast theory. It is shown that one projection image gives an information which does not allow a complete determination of the elliptical cross section, if an orientation of micropipe is not known. Another problem is a weak accuracy in estimating the diameters, partly because of using pink synchrotron radiation, which is necessary because a monochromatic beam intensity is not sufficient to reveal the weak contrast from a very small object. The general problems of accuracy in estimating the two diameters using the least square procedure are discussed. Two experimental examples are considered to demonstrate small as well as modest accuracies in estimating the diameters

  11. Extracting a Good Quality Frontal Face Image from a Low-Resolution Video Sequence

    DEFF Research Database (Denmark)

    Nasrollahi, Kamal; Moeslund, Thomas B.

    2011-01-01

    Feeding low-resolution and low-quality images, from inexpensive surveillance cameras, to systems like, e.g., face recognition, produces erroneous and unstable results. Therefore, there is a need for a mechanism to bridge the gap between on one hand low-resolution and low-quality images......, we use a learning-based super-resolution algorithm applied to the result of the reconstruction-based part to improve the quality by another factor of two. This results in an improvement factor of four for the entire system. The proposed system has been tested on 122 low-resolution sequences from two...... different databases. The experimental results show that the proposed system can indeed produce a high-resolution and good quality frontal face image from low-resolution video sequences....

  12. Magnetic resonance imaging of anterior cruciate ligament of the knee: a comparison of four sequences

    International Nuclear Information System (INIS)

    Casillas, C.; Marti-Bonmati, L.; Molla, E.; Ferrer, P.; Dosda, R.

    1999-01-01

    To compare the diagnostic efficacy of the four magnetic resonance imaging (MRI) sequences that compose the standard protocol for the study of the knee in our center when employed in the examination of anterior cruciate ligament (ACL). A prospective study was carried out based on MRI findings in the knees of 326 consecutive patients. Sagittal [proton density (PD w eighted turbo-spin-echo and T2*-weighted gradient echo], coronal (PD-weighted turbo-spin-echo with fat suppression) and transverse (T2*-weighted gradient echo with magnetization transfer) images were evaluated. Each sequence was analyzed independently by two radiologists, while another two assessed all the sequences together with the clinical findings. Four categories were established: normal ACL, partially torn, completely torn and synovialized. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) with respect to the definitive diagnosis were calculated for each sequence. The statistical analysis of the findings for each category was done using the chi-squared test and the Kappa test was employed to assess the degree of agreement. According to the final diagnosis, 263 ACL were normal, 29 were partially torn, 33 were completely torn and there was 1 case of synovialization associated with a completely torn ACL. The relationship between the analysis of the ACL according to each sequence and the definitive diagnosis was very significant (p<0.001) and the agreement was excellent. All the sequences presented similar levels of diagnostic precision. The coronal sequence had least number of diagnostic errors (2.1%). The combinations of imaging techniques that resulted in the lowest error rate with respect to the definitive diagnosis were coronal PD-weighted turbo-spin-echo with fat suppression and sagittal PD-weighted turbo-spin-echo. Coronal images are highly precise in the evaluation of ACL. Sagittal sequences are the most valid for diagnosis of torn ACL. Transverse

  13. Synthesis of long T silicon nanoparticles for hyperpolarized Si magnetic resonance imaging

    DEFF Research Database (Denmark)

    Atkins, T.M.; Ganguly, S.; Kauzlarich, S.M.

    2013-01-01

    silicide (Na Si) and silicon tetrachloride (SiCl) and were surface functionalized with a variety of passivating ligands. The synthesis scheme results in particles of diameter ~10 nm with long size-adjusted Si spin-lattice relaxation (T) times (>600 s), which are retained after hyperpolarization by low...

  14. STM imaging of buried P atoms in hydrogen-terminated Si for the fabrication of a Si:P quantum computer

    Energy Technology Data Exchange (ETDEWEB)

    Oberbeck, L.; Curson, N.J.; Hallam, T.; Simmons, M.Y.; Clark, R.G

    2004-10-01

    The fabrication of atomic-scale devices in silicon requires the encapsulation of dopant atoms which have been incorporated into the silicon surface at atomically precise positions using scanning tunnelling microscopy (STM) lithography. During silicon encapsulation, it is important to minimise segregation and diffusion of dopant atoms in order to retain the lithography defined device structure. Buried dopant imaging using STM is capable of imaging dopant atoms such as phosphorus after encapsulation in silicon several monolayers below the silicon surface, thus making it possible to check the integrity of the device structure. To fabricate buried phosphorus-doped samples, we use phosphine gas as a source of phosphorus atoms and incorporate the phosphorus atoms into a Si(001) surface during an annealing step. Molecular beam epitaxy is used to encapsulate the dopant atoms with several monolayers of silicon. After encapsulation, we hydrogen terminate the silicon surface in order to image the buried phosphorus dopants using STM. We show that a buried phosphorus atom appears as a bright glow superimposed on the silicon dimer structure in empty state STM images, whereas filled state images only show a very faint protrusion in the vicinity of the phosphorus atom. We highlight the importance of our results for the fabrication of atomic-scale devices.

  15. STM imaging of buried P atoms in hydrogen-terminated Si for the fabrication of a Si:P quantum computer

    International Nuclear Information System (INIS)

    Oberbeck, L.; Curson, N.J.; Hallam, T.; Simmons, M.Y.; Clark, R.G.

    2004-01-01

    The fabrication of atomic-scale devices in silicon requires the encapsulation of dopant atoms which have been incorporated into the silicon surface at atomically precise positions using scanning tunnelling microscopy (STM) lithography. During silicon encapsulation, it is important to minimise segregation and diffusion of dopant atoms in order to retain the lithography defined device structure. Buried dopant imaging using STM is capable of imaging dopant atoms such as phosphorus after encapsulation in silicon several monolayers below the silicon surface, thus making it possible to check the integrity of the device structure. To fabricate buried phosphorus-doped samples, we use phosphine gas as a source of phosphorus atoms and incorporate the phosphorus atoms into a Si(001) surface during an annealing step. Molecular beam epitaxy is used to encapsulate the dopant atoms with several monolayers of silicon. After encapsulation, we hydrogen terminate the silicon surface in order to image the buried phosphorus dopants using STM. We show that a buried phosphorus atom appears as a bright glow superimposed on the silicon dimer structure in empty state STM images, whereas filled state images only show a very faint protrusion in the vicinity of the phosphorus atom. We highlight the importance of our results for the fabrication of atomic-scale devices

  16. Moving target detection based on temporal-spatial information fusion for infrared image sequences

    Science.gov (United States)

    Toing, Wu-qin; Xiong, Jin-yu; Zeng, An-jun; Wu, Xiao-ping; Xu, Hao-peng

    2009-07-01

    Moving target detection and localization is one of the most fundamental tasks in visual surveillance. In this paper, through analyzing the advantages and disadvantages of the traditional approaches about moving target detection, a novel approach based on temporal-spatial information fusion is proposed for moving target detection. The proposed method combines the spatial feature in single frame and the temporal properties within multiple frames of an image sequence of moving target. First, the method uses the spatial image segmentation for target separation from background and uses the local temporal variance for extracting targets and wiping off the trail artifact. Second, the logical "and" operator is used to fuse the temporal and spatial information. In the end, to the fusion image sequence, the morphological filtering and blob analysis are used to acquire exact moving target. The algorithm not only requires minimal computation and memory but also quickly adapts to the change of background and environment. Comparing with other methods, such as the KDE, the Mixture of K Gaussians, etc., the simulation results show the proposed method has better validity and higher adaptive for moving target detection, especially in infrared image sequences with complex illumination change, noise change, and so on.

  17. RECOGNITION OF DRAINAGE TUNNELS DURING GLACIER LAKE OUTBURST EVENTS FROM TERRESTRIAL IMAGE SEQUENCES

    Directory of Open Access Journals (Sweden)

    E. Schwalbe

    2016-06-01

    Full Text Available In recent years, many glaciers all over the world have been distinctly retreating and thinning. One of the consequences of this is the increase of so called glacier lake outburst flood events (GLOFs. The mechanisms ruling such GLOF events are still not yet fully understood by glaciologists. Thus, there is a demand for data and measurements that can help to understand and model the phenomena. Thereby, a main issue is to obtain information about the location and formation of subglacial channels through which some lakes, dammed by a glacier, start to drain. The paper will show how photogrammetric image sequence analysis can be used to collect such data. For the purpose of detecting a subglacial tunnel, a camera has been installed in a pilot study to observe the area of the Colonia Glacier (Northern Patagonian Ice Field where it dams the Lake Cachet II. To verify the hypothesis, that the course of the subglacial tunnel is indicated by irregular surface motion patterns during its collapse, the camera acquired image sequences of the glacier surface during several GLOF events. Applying tracking techniques to these image sequences, surface feature motion trajectories could be obtained for a dense raster of glacier points. Since only a single camera has been used for image sequence acquisition, depth information is required to scale the trajectories. Thus, for scaling and georeferencing of the measurements a GPS-supported photogrammetric network has been measured. The obtained motion fields of the Colonia Glacier deliver information about the glacier’s behaviour before during and after a GLOF event. If the daily vertical glacier motion of the glacier is integrated over a period of several days and projected into a satellite image, the location and shape of the drainage channel underneath the glacier becomes visible. The high temporal resolution of the motion fields may also allows for an analysis of the tunnels dynamic in comparison to the changing

  18. Antibody-mediated platelet phagocytosis by human macrophages is inhibited by siRNA specific for sequences in the SH2 tyrosine kinase, Syk.

    Science.gov (United States)

    Lu, Ying; Wang, Weiming; Mao, Huiming; Hu, Hai; Wu, Yanling; Chen, Bing-Guan; Liu, Zhongmin

    2011-01-01

    Immune thrombocytopenia depends upon Fc receptor-mediated phagocytosis that involves signaling through the SH2 tyrosine kinase, Syk. We designed small interfering (siRNA) sequences complementary to Syk coding regions to decrease the expression of Syk in the human macrophage cell line, THP-1. To evaluate the functional effect of siRNA on phagocytosis, we developed a new in vitro assay for antibody-mediated platelet ingestion by THP-1 cells. Incubation of THP-1 cells at 37°C with fluorescence-labeled platelets and anti-platelet antibody promoted ingestion of platelets that could be quantitated by flow cytometry. Transfection of THP-1 cells with Syk-specific siRNA resulted in a reduction in the amount of FcγRII-associated Syk protein. Coincident with decreased Syk expression, we observed inhibition of antibody-mediated platelet ingestion. These results confirm a key role for Syk in antibody-mediated phagocytosis and suggest Syk-specific siRNA as a possible therapeutic candidate for immune thrombocytopenia. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Magnetic nanoparticle imaging by random and maximum length sequences of inhomogeneous activation fields.

    Science.gov (United States)

    Baumgarten, Daniel; Eichardt, Roland; Crevecoeur, Guillaume; Supriyanto, Eko; Haueisen, Jens

    2013-01-01

    Biomedical applications of magnetic nanoparticles require a precise knowledge of their biodistribution. From multi-channel magnetorelaxometry measurements, this distribution can be determined by means of inverse methods. It was recently shown that the combination of sequential inhomogeneous excitation fields in these measurements is favorable regarding the reconstruction accuracy when compared to homogeneous activation . In this paper, approaches for the determination of activation sequences for these measurements are investigated. Therefor, consecutive activation of single coils, random activation patterns and families of m-sequences are examined in computer simulations involving a sample measurement setup and compared with respect to the relative condition number of the system matrix. We obtain that the values of this condition number decrease with larger number of measurement samples for all approaches. Random sequences and m-sequences reveal similar results with a significant reduction of the required number of samples. We conclude that the application of pseudo-random sequences for sequential activation in the magnetorelaxometry imaging of magnetic nanoparticles considerably reduces the number of required sequences while preserving the relevant measurement information.

  20. Correction of projective distortion in long-image-sequence mosaics without prior information

    Science.gov (United States)

    Yang, Chenhui; Mao, Hongwei; Abousleman, Glen; Si, Jennie

    2010-04-01

    Image mosaicking is the process of piecing together multiple video frames or still images from a moving camera to form a wide-area or panoramic view of the scene being imaged. Mosaics have widespread applications in many areas such as security surveillance, remote sensing, geographical exploration, agricultural field surveillance, virtual reality, digital video, and medical image analysis, among others. When mosaicking a large number of still images or video frames, the quality of the resulting mosaic is compromised by projective distortion. That is, during the mosaicking process, the image frames that are transformed and pasted to the mosaic become significantly scaled down and appear out of proportion with respect to the mosaic. As more frames continue to be transformed, important target information in the frames can be lost since the transformed frames become too small, which eventually leads to the inability to continue further. Some projective distortion correction techniques make use of prior information such as GPS information embedded within the image, or camera internal and external parameters. Alternatively, this paper proposes a new algorithm to reduce the projective distortion without using any prior information whatsoever. Based on the analysis of the projective distortion, we approximate the projective matrix that describes the transformation between image frames using an affine model. Using singular value decomposition, we can deduce the affine model scaling factor that is usually very close to 1. By resetting the image scale of the affine model to 1, the transformed image size remains unchanged. Even though the proposed correction introduces some error in the image matching, this error is typically acceptable and more importantly, the final mosaic preserves the original image size after transformation. We demonstrate the effectiveness of this new correction algorithm on two real-world unmanned air vehicle (UAV) sequences. The proposed method is

  1. Effects of imaging gradients in sequences with varying longitudinal storage time-Case of diffusion exchange imaging.

    Science.gov (United States)

    Lasič, Samo; Lundell, Henrik; Topgaard, Daniel; Dyrby, Tim B

    2018-04-01

    To illustrate the potential bias caused by imaging gradients in correlation MRI sequences using longitudinal magnetization storage (LS) and examine the case of filter exchange imaging (FEXI) yielding maps of the apparent exchange rate (AXR). The effects of imaging gradients in FEXI were observed on yeast cells. To analyze the AXR bias, signal evolution was calculated by applying matrix exponential operators. A sharp threshold for the slice thickness was identified, below which the AXR is increasingly underestimated. The bias can be understood in terms of an extended low-pass diffusion filtering during the LS interval, which is more pronounced at lower exchange rates. For a total exchange rate constant larger than 1 s -1 , the AXR bias is expected to be negligible when slices thicker than 2.5 mm are used. In correlation experiments like FEXI, relying on LS with variable duration, imaging gradients may cause disrupting effects that cannot be easily mitigated and should be carefully considered for unbiased results. In typical clinical applications of FEXI, the imaging gradients are expected to cause a negligible AXR bias. However, the AXR bias may be significant in preclinical settings or whenever thin imaging slices are used. Magn Reson Med 79:2228-2235, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  2. Automatic registration of panoramic image sequence and mobile laser scanning data using semantic features

    Science.gov (United States)

    Li, Jianping; Yang, Bisheng; Chen, Chi; Huang, Ronggang; Dong, Zhen; Xiao, Wen

    2018-02-01

    Inaccurate exterior orientation parameters (EoPs) between sensors obtained by pre-calibration leads to failure of registration between panoramic image sequence and mobile laser scanning data. To address this challenge, this paper proposes an automatic registration method based on semantic features extracted from panoramic images and point clouds. Firstly, accurate rotation parameters between the panoramic camera and the laser scanner are estimated using GPS and IMU aided structure from motion (SfM). The initial EoPs of panoramic images are obtained at the same time. Secondly, vehicles in panoramic images are extracted by the Faster-RCNN as candidate primitives to be matched with potential corresponding primitives in point clouds according to the initial EoPs. Finally, translation between the panoramic camera and the laser scanner is refined by maximizing the overlapping area of corresponding primitive pairs based on the Particle Swarm Optimization (PSO), resulting in a finer registration between panoramic image sequences and point clouds. Two challenging urban scenes were experimented to assess the proposed method, and the final registration errors of these two scenes were both less than three pixels, which demonstrates a high level of automation, robustness and accuracy.

  3. Object-Oriented Query Language For Events Detection From Images Sequences

    Science.gov (United States)

    Ganea, Ion Eugen

    2015-09-01

    In this paper is presented a method to represent the events extracted from images sequences and the query language used for events detection. Using an object oriented model the spatial and temporal relationships between salient objects and also between events are stored and queried. This works aims to unify the storing and querying phases for video events processing. The object oriented language syntax used for events processing allow the instantiation of the indexes classes in order to improve the accuracy of the query results. The experiments were performed on images sequences provided from sport domain and it shows the reliability and the robustness of the proposed language. To extend the language will be added a specific syntax for constructing the templates for abnormal events and for detection of the incidents as the final goal of the research.

  4. Minimization of Dead-Periods in MRI Pulse Sequences for Imaging Oblique Planes

    Science.gov (United States)

    Atalar, Ergin; McVeigh, Elliot R.

    2007-01-01

    With the advent of breath-hold MR cardiac imaging techniques, the minimization of TR and TE for oblique planes has become a critical issue. The slew rates and maximum currents of gradient amplifiers limit the minimum possible TR and TE by adding dead-periods to the pulse sequences. We propose a method of designing gradient waveforms that will be applied to the amplifiers instead of the slice, readout, and phase encoding waveforms. Because this method ensures that the gradient amplifiers will always switch at their maximum slew rate, it results in the minimum possible dead-period for given imaging parameters and scan plane position. A GRASS pulse sequence has been designed and ultra-short TR and TE values have been obtained with standard gradient amplifiers and coils. For some oblique slices, we have achieved shorter TR and TE values than those for nonoblique slices. PMID:7869900

  5. [Study on method of tracking the active cells in image sequences based on EKF-PF].

    Science.gov (United States)

    Tang, Chunming; Liu, Ying

    2013-02-01

    In cell image sequences, due to the nonlinear and nonGaussian motion characteristics of active cells, the accurate prediction and tracking is still an unsolved problem. We applied extended Kalman particle filter (EKF-PF) here in our study, attempting to solve the problem. Firstly we confirmed the existence and positions of the active cells. Then we established a motion model and improved it via adding motion angle estimation. Next we predicted motion parameters, such as displacement, velocity, accelerated velocity and motion angle, in region centers of the cells being tracked. Finally we obtained the motion traces of active cells. There were fourteen active cells in three image sequences which have been tracked. The errors were less than 2.5 pixels when the prediction values were compared with actual values. It showed that the presented algorithm may basically reach the solution of accurate predition and tracking of the active cells.

  6. Visualization and correction of automated segmentation, tracking and lineaging from 5-D stem cell image sequences.

    Science.gov (United States)

    Wait, Eric; Winter, Mark; Bjornsson, Chris; Kokovay, Erzsebet; Wang, Yue; Goderie, Susan; Temple, Sally; Cohen, Andrew R

    2014-10-03

    Neural stem cells are motile and proliferative cells that undergo mitosis, dividing to produce daughter cells and ultimately generating differentiated neurons and glia. Understanding the mechanisms controlling neural stem cell proliferation and differentiation will play a key role in the emerging fields of regenerative medicine and cancer therapeutics. Stem cell studies in vitro from 2-D image data are well established. Visualizing and analyzing large three dimensional images of intact tissue is a challenging task. It becomes more difficult as the dimensionality of the image data increases to include time and additional fluorescence channels. There is a pressing need for 5-D image analysis and visualization tools to study cellular dynamics in the intact niche and to quantify the role that environmental factors play in determining cell fate. We present an application that integrates visualization and quantitative analysis of 5-D (x,y,z,t,channel) and large montage confocal fluorescence microscopy images. The image sequences show stem cells together with blood vessels, enabling quantification of the dynamic behaviors of stem cells in relation to their vascular niche, with applications in developmental and cancer biology. Our application automatically segments, tracks, and lineages the image sequence data and then allows the user to view and edit the results of automated algorithms in a stereoscopic 3-D window while simultaneously viewing the stem cell lineage tree in a 2-D window. Using the GPU to store and render the image sequence data enables a hybrid computational approach. An inference-based approach utilizing user-provided edits to automatically correct related mistakes executes interactively on the system CPU while the GPU handles 3-D visualization tasks. By exploiting commodity computer gaming hardware, we have developed an application that can be run in the laboratory to facilitate rapid iteration through biological experiments. We combine unsupervised image

  7. The value of MR imaging of PDFASAT sequence in the diagnosis of extremities occult fractures

    International Nuclear Information System (INIS)

    Lu Lingquan; Xu Mingshen; Wu Qianzhi; Mao Chunnan; Wang Shuzi; Zhou Xingfan; Wang Liping

    2004-01-01

    Objective: To investigate the value of MR imaging of proton density weighted-fat saturated (PDFASAT) sequence in detecting the occult fracture of extremities. Methods: Thirty-one patients with acute trauma were studied using radiography and MR imaging within 45 days. MR sequences included FSE T 1 WI, T 2 WI, and PDFASAT. 21 occult fractures occurred in the knee joint, 6 in the hip joint, 1 in the elbow joint, 2 in the shoulder, and 1 in the ankle. Results: All 31 cases had normal radiographic results. 10 cases with proximal fibula, 4 with proximal tibia and 7 with femur condyle occult fractures were found in 21 knee joint acute trauma cases. 2 cases with intertrochanteric, 2 with femoral neck and 2 with cotyle occult fractures were found in 6 hip joint trauma cases. 2 proximal humerus occult fractures were found in 2 shoulder cases. 1 distal humerus and 1 distal fibula occult fracture was found in elbow and ankle cases. MR imaging demonstrated irregular linear low signal in the subcortical region on both T 1 WI and T 2 WI, and high signal changes around low signal were seen on T 2 WI in some cases. The high signal in PDFASAT sequence was more remarkable and wider than that on both T 1 WI and T 2 WI. Conclusion: MR imaging could determine the diagnosis of acute and chronic occult fractures. MRI should be the next choice when plain films fail to reveal suspected fractures in setting of suggestive symptoms and positive physical examination. PDFASAT would be the best effective sequence among the T 1 WI, T 2 WI, and PDFASAT. (author)

  8. Fast triple-spin-echo Dixon (FTSED) sequence for water and fat imaging

    Czech Academy of Sciences Publication Activity Database

    Kořínek, Radim; Bartušek, Karel; Starčuk jr., Zenon

    2017-01-01

    Roč. 37, APR (2017), s. 164-170 ISSN 0730-725X R&D Projects: GA MŠk ED0017/01/01; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : fast triple-spin-echo Dixon * sequence * MRI * fat fraction * water-fat * ultra-high field * 9.4 T * FTSED Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Radiology, nuclear medicine and medical imaging Impact factor: 2.225, year: 2016

  9. Comparison of T1rho imaging between spoiled gradient echo (SPGR) and balanced steady state free precession (b-FFE) sequence of knee cartilage at 3 T MRI

    Energy Technology Data Exchange (ETDEWEB)

    Nozaki, Taiki; Kaneko, Yasuhito; Yu, Hon J. [Department of Radiological Sciences, University of California, Irvine, CA (United States); Kaneshiro, Kayleigh [School of Medicine, University of California, Irvine, CA (United States); Schwarzkopf, Ran [Department of Orthopaedic Surgery, University of California, Irvine, CA (United States); Yoshioka, Hiroshi, E-mail: hiroshi@uci.edu [Department of Radiological Sciences, University of California, Irvine, CA (United States)

    2015-07-15

    Highlights: • T1rho values on b-FFE tend to be higher than those on SPGR. • The reproducibility of T1rho cartilage segmentation is higher on SPGR than b-FFE. • There is angular variation of T1rho profiles. • Average T1rho values in the superficial layer are higher than in the deep layer. - Abstract: Purpose: To investigate the difference in T1rho profiles of the entire femoral cartilage between SPGR and b-FFE sequences at 3.0 T. Materials and methods: 20 healthy volunteers were enrolled in this study. T1rho images of each subject were acquired with two types of pulse sequences: SPGR and b-FFE. Femoral cartilage segmentation was performed by two independent raters slice-by-slice using Matlab. Inter- and intra-observer reproducibility between the two imaging protocols was calculated. The relative signal intensity (SI) of cartilage, subchondral bone marrow, joint effusion, and the relative signal contrast between structures of the knee were quantitatively measured. The difference in T1rho values between SPGR and b-FFE sequences was statistically analyzed using the Wilcoxon signed-rank test. Results: The average T1rho value of the entire femoral cartilage with b-FFE was significantly higher compared to SPGR (p < 0.05). The reproducibility of the segmented area and T1rho values was superior with SPGR compared to b-FFE. The inter-class correlation coefficient was 0.846 on SPGR and 0.824 on b-FFE. The intra-class correlation coefficient of T1rho values was 0.878 on SPGR and 0.836 on b-FFE. The two imaging techniques demonstrated different signal and contrast characteristics. The relative SI of fluid was significantly higher on SPGR, while the relative SI of subchondral bone was significantly higher on b-FFE (p < 0.001). There were also significant differences in the relative contrast between fluid–cartilage, fluid–subchondral bone, and cartilage–subchondral bone between the two sequences (all p < 0.001). Conclusion: We need to pay attention to differences in

  10. On the Farey sequence and its augmentation for applications to image analysis

    Directory of Open Access Journals (Sweden)

    Pratihar Sanjoy

    2017-09-01

    Full Text Available We introduce a novel concept of the augmented Farey table (AFT. Its purpose is to store the ranks of fractions of a Farey sequence in an efficient manner so as to return the rank of any query fraction in constant time. As a result, computations on the digital plane can be crafted down to simple integer operations; for example, the tasks like determining the extent of collinearity of integer points or of parallelism of straight lines—often required to solve many image-analytic problems—can be made fast and efficient through an appropriate AFT-based tool. We derive certain interesting characterizations of an AFT for its efficient generation. We also show how, for a fraction not present in a Farey sequence, the rank of the nearest fraction in that sequence can efficiently be obtained by the regula falsi method from the AFT concerned. To assert its merit, we show its use in two applications—one in polygonal approximation of digital curves and the other in skew correction of engineering drawings in document images. Experimental results indicate the potential of the AFT in such image-analytic applications.

  11. Stellar imager (SI): enhancements to the mission enabled by the constellation architecture (Ares I/Ares V)

    Science.gov (United States)

    Carpenter, Kenneth G.; Karovska, Margarita; Lyon, Richard G.; Mozurkewich, D.; Schrijver, Carolus

    2009-08-01

    Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI) with over 200x the resolution of HST. It will enable 0.1 milli-arcsec spectral imaging of stellar surfaces and the Universe in general and open an enormous new "discovery space" for astrophysics with its combination of high angular resolution, dynamic imaging, and spectral energy resolution. SI's goal is to study the role of magnetism in the Universe and revolutionize our understanding of: 1) Solar/Stellar Magnetic Activity and their impact on Space Weather, Planetary Climates, and Life, 2) Magnetic and Accretion Processes and their roles in the Origin & Evolution of Structure and in the Transport of Matter throughout the Universe, 3) the close-in structure of Active Galactic Nuclei and their winds, and 4) Exo-Solar Planet Transits and Disks. SI is a "Landmark/Discovery Mission" in 2005 Heliophysics Roadmap and a candidate UVOI in the 2006 Astrophysics Strategic Plan and is targeted for launch in the mid-2020's. It is a NASA Vision Mission and has been recommended for further study in a 2008 NRC report on missions potentially enabled/enhanced by an Ares V launch. In this paper, we discuss the science goals and required capabilities of SI, the baseline architecture of the mission assuming launch on one or more Delta rockets, and then the potential significant enhancements to the SI science and mission architecture that would be made possible by a launch in the larger volume Ares V payload fairing, and by servicing options under consideration in the Constellation program.

  12. Stellar Imager (SI): Enhancements to the Mission Enabled by the Constellation Architecture (Ares I/Ares V)

    Science.gov (United States)

    Carpenter, Kenneth G.; Lyon, Richard G.; Karovska, Margarita; Mozurkwich, D.; Schrijver, Carolus

    2009-01-01

    Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI) with over 200x the resolution of HST. It will enable 0.1 milli-aresec spectral imaging of stellar surfaces and the Universe in general and open an enormous new "discovery space" for astrophysics with its combination of high angular resolution, dynamic imaging , and spectral energy resolution. SI's goal is to study the role of magnetism in the Universe and revolutionize our understanding of 1) Solar/Stellar Magnetic Activity and their impact on Space Weather, Planetary Climates, and Life, 2) Magnetic and Accretion Processes and their roles in the Origin & Evolution of Structure and in the Transport of Matter throughout the Universe, 3) the close-in structure of Active Galactic Nuclei and their winds, and 4) Exo-Solar Planet Transits and Disks. SI is a "Landmark-Discovery Mission" in 2005 Heliophysics Roadmap and a candidate UVOI in the 2006 Astrophysics Strategic Plan and is targeted for launch in the mid-2020's. It is a NASA Vision Mission and has been recommended for further study in a 2008 NRC report on missions potentially enabled/enhanced by an Ares V launch. In this paper, we discuss the science goals and required capabilities of SI, the baseline architecture of the mission assuming launch on one or more Delta rockets, and then the potential significant enhancements to the SI science and mission architecture that would be made possible by a launch in the larger volume Ares V payload fairing, and by servicing options under consideration in the Constellation program.

  13. Applicability of the 3D-VIBE sequence to whole brain imaging

    International Nuclear Information System (INIS)

    Makabe, Takeshi; Nakamura, Manami; Moriyama, Ryo

    2009-01-01

    The volumetric interpolated breath-hold examination (VIBE) method has been developed imaging also holds its breath in an abdomen, and to do three-dimensional T1WI in possible time in gradient echo sequence, and applied to dynamic study mainly and planning for time reduction using an interpolation and partial fourier. We considered the condition for imaging to do whole brain as high resolution image using VIBE. Even if base matrix was maintained when an interpolation and partial fourier were used too much excessively by Phantom experiment, the resolution of multiplanar reconstruction (MPR) image fell. There was a limit of the interpolation therefore to maintain the resolution as voxel. Signal-to-noise ratio (SNR) fell by flip angle (FA) increase by the applicability to the head, and peak existed in about 15 deg in contrast-to-noise ratio (CNR) of white matter and gray matter. Therefore by it's clinical and optimizing the imaging condition of VIBE, whole brain, it was imaging possible in about 3 minutes as high resolution image. (author)

  14. Noninvasive imaging of three-dimensional cardiac activation sequence during pacing and ventricular tachycardia.

    Science.gov (United States)

    Han, Chengzong; Pogwizd, Steven M; Killingsworth, Cheryl R; He, Bin

    2011-08-01

    Imaging cardiac excitation within ventricular myocardium is important in the treatment of cardiac arrhythmias and might help improve our understanding of arrhythmia mechanisms. This study sought to rigorously assess the imaging performance of a 3-dimensional (3D) cardiac electrical imaging (3DCEI) technique with the aid of 3D intracardiac mapping from up to 216 intramural sites during paced rhythm and norepinephrine (NE)-induced ventricular tachycardia (VT) in the rabbit heart. Body surface potentials and intramural bipolar electrical recordings were simultaneously measured in a closed-chest condition in 13 healthy rabbits. Single-site pacing and dual-site pacing were performed from ventricular walls and septum. VTs and premature ventricular complexes (PVCs) were induced by intravenous NE. Computed tomography images were obtained to construct geometry models. The noninvasively imaged activation sequence correlated well with invasively measured counterpart, with a correlation coefficient of 0.72 ± 0.04, and a relative error of 0.30 ± 0.02 averaged over 520 paced beats as well as 73 NE-induced PVCs and VT beats. All PVCs and VT beats initiated in the subendocardium by a nonreentrant mechanism. The averaged distance from the imaged site of initial activation to the pacing site or site of arrhythmias determined from intracardiac mapping was ∼5 mm. For dual-site pacing, the double origins were identified when they were located at contralateral sides of ventricles or at the lateral wall and the apex. 3DCEI can noninvasively delineate important features of focal or multifocal ventricular excitation. It offers the potential to aid in localizing the origins and imaging activation sequences of ventricular arrhythmias, and to provide noninvasive assessment of the underlying arrhythmia mechanisms. Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  15. Characterization of platelet adhesion under flow using microscopic image sequence analysis.

    Science.gov (United States)

    Machin, M; Santomaso, A; Cozzi, M R; Battiston, M; Mazzuccato, M; De Marco, L; Canu, P

    2005-07-01

    A method for quantitative analysis of platelet deposition under flow is discussed here. The model system is based upon perfusion of blood platelets over an adhesive substrate immobilized on a glass coverslip acting as the lower surface of a rectangular flow chamber. The perfusion apparatus is mounted onto an inverted microscope equipped with epifluorescent illumination and intensified CCD video camera. Characterization is based on information obtained from a specific image analysis method applied to continuous sequences of microscopical images. Platelet recognition across the sequence of images is based on a time-dependent, bidimensional, gaussian-like pdf. Once a platelet is located,the variation of its position and shape as a function of time (i.e., the platelet history) can be determined. Analyzing the history we can establish if the platelet is moving on the surface, the frequency of this movement and the distance traveled before its resumes the velocity of a non-interacting cell. Therefore, we can determine how long the adhesion would last which is correlated to the resistance of the platelet-substrate bond. This algorithm enables the dynamic quantification of trajectories, as well as residence times, arrest and release frequencies for a high numbers of platelets at the same time. Statistically significant conclusions on platelet-surface interactions can then be obtained. An image analysis tool of this kind can dramatically help the investigation and characterization of the thrombogenic properties of artificial surfaces such as those used in artificial organs and biomedical devices.

  16. MULTI-EPOCH IMAGING POLARIMETRY OF THE SiO MASERS IN THE EXTENDED ATMOSPHERE OF THE MIRA VARIABLE TX CAM

    International Nuclear Information System (INIS)

    Kemball, Athol J.; Diamond, Philip J.; Gonidakis, Ioannis; Mitra, Modhurita; Yim, Kijeong; Pan, K.-C.; Chiang, H.-F.

    2009-01-01

    We present a time series of synoptic images of the linearly polarized v = 1, J = 1-0 SiO maser emission toward the Mira variable, TX Cam. These data comprise 43 individual epochs at an approximate biweekly sampling over an optical pulsation phase range of φ = 0.68 to φ = 1.82. The images have an angular resolution of ∼500 μas and were obtained using the Very Long Baseline Array (VLBA), operating in the 43 GHz band in spectral-line, polarization mode. We have previously published the total intensity time series for this pulsation phase range; this paper serves to present the linearly polarized image sequence and an associated animation representing the evolution of the linear polarization morphology over time. We find a predominantly tangential polarization morphology, a high degree of persistence in linear polarization properties over individual component lifetimes, and stronger linear polarization in the inner projected shell than at larger projected shell radii. We present an initial polarization proper motion analysis examining the possible dynamical influence of magnetic fields in component motions in the extended atmospheres of late-type, evolved stars.

  17. Selection of optimal pulse sequences for conventional and dynamic MR imaging with Gd-DTPA; A fundamental study

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Miho; Kita, Keisuke; Maeda, Masayuki (Wakayama Medical Coll. (Japan)) (and others)

    1989-11-01

    Gadolinium-DTPA (Gd-DTPA) enhances contrast between tissues in magnetic resonance (MR) imaging. The enhancement of tissues depends partly upon the pulse sequences, and the optimal pulse sequence is also influenced by the tissue cncentration of Gd-DTPA. We prepared phantoms of 25% albumin solutions with various concentrations of Gd-DTPA, and imaged them using various pulse sequences with 1.5-T MR system. We also performed MR imaging of 16 patients with tumors (10 brain tumors and 6 hepatic tumors) before and after intravenous administration of Gd-DTPA (0.1 mmol/kg); 6 patients with hepatic tumors underwent dynamic MR imaging during suspended respiration. We made a theoretical equation to calculate the concentration of Gd-DTPA and estimated its tissue concentration in tumors at 0{approx}0.2 mmol/kg. Within these tissue concentrations, the enhancement-to-noise (E/N) ratio was larger in FISP (flip angle of 90deg, TR pf 300 msec, minimal TE) and SE (TR of 400 msec, minimal TE) sequences than in other sequences observed. These sequences may be preferable for conventional enhanced-MRI. Among the pulse sequences with TR of less than 100 msec, FISP (flip angle of 90deg, TR of less than 100 msec, minimal TE) had the largest E/N ratio; which may be useful for dynamic MRI during suspended respiration. The importance of selecting the optimal pulse sequences according to the imaging modality used will be discussed. (author).

  18. A new feedback image encryption scheme based on perturbation with dynamical compound chaotic sequence cipher generator

    Science.gov (United States)

    Tong, Xiaojun; Cui, Minggen; Wang, Zhu

    2009-07-01

    The design of the new compound two-dimensional chaotic function is presented by exploiting two one-dimensional chaotic functions which switch randomly, and the design is used as a chaotic sequence generator which is proved by Devaney's definition proof of chaos. The properties of compound chaotic functions are also proved rigorously. In order to improve the robustness against difference cryptanalysis and produce avalanche effect, a new feedback image encryption scheme is proposed using the new compound chaos by selecting one of the two one-dimensional chaotic functions randomly and a new image pixels method of permutation and substitution is designed in detail by array row and column random controlling based on the compound chaos. The results from entropy analysis, difference analysis, statistical analysis, sequence randomness analysis, cipher sensitivity analysis depending on key and plaintext have proven that the compound chaotic sequence cipher can resist cryptanalytic, statistical and brute-force attacks, and especially it accelerates encryption speed, and achieves higher level of security. By the dynamical compound chaos and perturbation technology, the paper solves the problem of computer low precision of one-dimensional chaotic function.

  19. Time integration and statistical regulation applied to mobile objects detection in a sequence of images

    International Nuclear Information System (INIS)

    Letang, Jean-Michel

    1993-01-01

    This PhD thesis deals with the detection of moving objects in monocular image sequences. The first section presents the inherent problems of motion analysis in real applications. We propose a method robust to perturbations frequently encountered during acquisition of outdoor scenes. It appears three main directions for investigations, all of them pointing out the importance of the temporal axis, which is a specific dimension for motion analysis. In the first part, the image sequence is considered as a set of temporal signals. The temporal multi-scale decomposition enables the characterization of various dynamical behaviors of the objects being in the scene at a given instant. A second module integrates motion information. This elementary trajectography of moving objects provides a temporal prediction map, giving a confidence level of motion presence. Interactions between both sets of data are expressed within a statistical regularization. Markov random field models supply a formal framework to convey a priori knowledge of the primitives to be evaluated. A calibration method with qualitative boxes is presented to estimate model parameters. Our approach requires only simple computations and leads to a rather fast algorithm, that we evaluate in the last section over various typical sequences. (author) [fr

  20. PoPMuSiC 2.1: a web server for the estimation of protein stability changes upon mutation and sequence optimality

    Directory of Open Access Journals (Sweden)

    Rooman Marianne

    2011-05-01

    Full Text Available Abstract Background The rational design of modified proteins with controlled stability is of extreme importance in a whole range of applications, notably in the biotechnological and environmental areas, where proteins are used for their catalytic or other functional activities. Future breakthroughs in medical research may also be expected from an improved understanding of the effect of naturally occurring disease-causing mutations on the molecular level. Results PoPMuSiC-2.1 is a web server that predicts the thermodynamic stability changes caused by single site mutations in proteins, using a linear combination of statistical potentials whose coefficients depend on the solvent accessibility of the mutated residue. PoPMuSiC presents good prediction performances (correlation coefficient of 0.8 between predicted and measured stability changes, in cross validation, after exclusion of 10% outliers. It is moreover very fast, allowing the prediction of the stability changes resulting from all possible mutations in a medium size protein in less than a minute. This unique functionality is user-friendly implemented in PoPMuSiC and is particularly easy to exploit. Another new functionality of our server concerns the estimation of the optimality of each amino acid in the sequence, with respect to the stability of the structure. It may be used to detect structural weaknesses, i.e. clusters of non-optimal residues, which represent particularly interesting sites for introducing targeted mutations. This sequence optimality data is also expected to have significant implications in the prediction and the analysis of particular structural or functional protein regions. To illustrate the interest of this new functionality, we apply it to a dataset of known catalytic sites, and show that a much larger than average concentration of structural weaknesses is detected, quantifying how these sites have been optimized for function rather than stability. Conclusion The

  1. Characterization of high density SiPM non-linearity and energy resolution for prompt gamma imaging applications

    Science.gov (United States)

    Regazzoni, V.; Acerbi, F.; Cozzi, G.; Ferri, A.; Fiorini, C.; Paternoster, G.; Piemonte, C.; Rucatti, D.; Zappalà, G.; Zorzi, N.; Gola, A.

    2017-07-01

    Fondazione Bruno Kessler (FBK) (Trento, Italy) has recently introduced High Density (HD) and Ultra High-Density (UHD) SiPMs, featuring very small micro-cell pitch. The high cell density is a very important factor to improve the linearity of the SiPM in high-dynamic-range applications, such as the scintillation light readout in high-energy gamma-ray spectroscopy and in prompt gamma imaging for proton therapy. The energy resolution at high energies is a trade-off between the excess noise factor caused by the non-linearity of the SiPM and the photon detection efficiency of the detector. To study these effects, we developed a new setup that simulates the LYSO light emission in response to gamma photons up to 30 MeV, using a pulsed light source. We measured the non-linearity and energy resolution vs. energy of the FBK RGB-HD e RGB-UHD SiPM technologies. We considered five different cell sizes, ranging from 10 μm up to 25 μm. With the UHD technology we were able to observe a remarkable reduction of the SiPM non-linearity, less than 5% at 5 MeV with 10 μm cells, which should be compared to a non-linearity of 50% with 25 μm-cell HD-SiPMs. With the same setup, we also measured the different components of the energy resolution (intrinsic, statistical, detector and electronic noise) vs. cell size, over-voltage and energy and we separated the different sources of excess noise factor.

  2. Evaluation of chirp reversal power modulation sequence for contrast agent imaging

    International Nuclear Information System (INIS)

    Novell, A; Sennoga, CA; Escoffre, JM; Chaline, J; Bouakaz, A

    2014-01-01

    Over the last decade, significant research effort has been focused on the use of chirp for contrast agent imaging because chirps are known to significantly increase imaging contrast-to-noise ratio (CNR). New imaging schemes, such as chirp reversal (CR), have been developed to improve contrast detection by increasing non-linear microbubble responses. In this study we evaluated the contrast enhancement efficiency of various chirped imaging sequences in combination with well-established imaging schemes such as power modulation (PM) and pulse inversion (PI). The imaging schemes tested were implemented on a fully programmable open scanner and evaluated by ultrasonically scanning (excitation frequency of 2.5 MHz; amplitude of 350 kPa) a tissue-mimicking flow phantom comprising a 4 mm diameter tube through which aqueous dispersions (dilution fraction of 1/2000) of the commercial ultrasound contrast agent, SonoVue ® were continuously circulated. The recovery of non-linear microbubble responses after chirp compression requires the development and the optimization of a specific filter. A compression filter was therefore designed and used to compress and extract several non-linear components from the received microbubble responses. The results showed that using chirps increased the image CNR by approximately 10 dB, as compared to conventional Gaussian apodized sine burst excitation but degraded the axial resolution by a factor of 1.4, at −3 dB. We demonstrated that the highest CNR and contrast-to-noise ratio (CTR) were achievable when CR was combined with PM as compared to other imaging schemes such as PI. (paper)

  3. Detection of SiO2 nanoparticles in lung tissue by ToF-SIMS imaging and fluorescence microscopy.

    Science.gov (United States)

    Veith, Lothar; Vennemann, Antje; Breitenstein, Daniel; Engelhard, Carsten; Wiemann, Martin; Hagenhoff, Birgit

    2017-07-10

    The direct detection of nanoparticles in tissues at high spatial resolution is a current goal in nanotoxicology. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is widely used for the direct detection of inorganic and organic substances with high spatial resolution but its capability to detect nanoparticles in tissue sections is still insufficiently explored. To estimate the applicability of this technique for nanotoxicological questions, comparative studies with established techniques on the detection of nanoparticles can offer additional insights. Here, we compare ToF-SIMS imaging data with sub-micrometer spatial resolution to fluorescence microscopy imaging data to explore the usefulness of ToF-SIMS for the detection of nanoparticles in tissues. SiO 2 nanoparticles with a mean diameter of 25 nm, core-labelled with fluorescein isothiocyanate, were intratracheally instilled into rat lungs. Subsequently, imaging of lung cryosections was performed with ToF-SIMS and fluorescence microscopy. Nanoparticles were successfully detected with ToF-SIMS in 3D microanalysis mode based on the lateral distribution of SiO 3 - (m/z 75.96), which was co-localized with the distribution pattern that was obtained from nanoparticle fluorescence. In addition, the lateral distribution of protein (CN - , m/z 26.00) and phosphate based signals (PO 3 - , m/z 78.96) originating from the tissue material could be related to the SiO 3 - lateral distribution. In conclusion, ToF-SIMS is suitable to directly detect and laterally resolve SiO 2 nanomaterials in biological tissue at sufficient intensity levels. At the same time, information about the chemical environment of the nanoparticles in the lung tissue sections is obtained.

  4. Managing complex processing of medical image sequences by program supervision techniques

    Science.gov (United States)

    Crubezy, Monica; Aubry, Florent; Moisan, Sabine; Chameroy, Virginie; Thonnat, Monique; Di Paola, Robert

    1997-05-01

    Our objective is to offer clinicians wider access to evolving medical image processing (MIP) techniques, crucial to improve assessment and quantification of physiological processes, but difficult to handle for non-specialists in MIP. Based on artificial intelligence techniques, our approach consists in the development of a knowledge-based program supervision system, automating the management of MIP libraries. It comprises a library of programs, a knowledge base capturing the expertise about programs and data and a supervision engine. It selects, organizes and executes the appropriate MIP programs given a goal to achieve and a data set, with dynamic feedback based on the results obtained. It also advises users in the development of new procedures chaining MIP programs.. We have experimented the approach for an application of factor analysis of medical image sequences as a means of predicting the response of osteosarcoma to chemotherapy, with both MRI and NM dynamic image sequences. As a result our program supervision system frees clinical end-users from performing tasks outside their competence, permitting them to concentrate on clinical issues. Therefore our approach enables a better exploitation of possibilities offered by MIP and higher quality results, both in terms of robustness and reliability.

  5. Artifact free T2{sup *}-weighted imaging at high spatial resolution using segmented EPI sequences

    Energy Technology Data Exchange (ETDEWEB)

    Heiler, Patrick Michael; Schad, Lothar Rudi [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine; Schmitter, Sebastian [German Cancer Research Center, Heidelberg (Germany). Dept. of Medical Physics in Radiology

    2010-07-01

    The aim of this work was the development of novel measurement techniques that acquire high resolution T2{sup *}-weighted datasets in measurement times as short as possible without suffering from noticeable blurring and ghosting artifacts. Therefore, two new measurement techniques were developed that acquire a smoother k-space than generic multi shot echo planar imaging sequences. One is based on the principle of echo train shifting, the other on the reversed gradient method. Simulations and phantom measurements demonstrate that echo train shifting works properly and reduces artifacts in multi shot echo planar imaging. For maximum SNR-efficiency this technique was further improved by adding a second contrast. Both contrasts can be acquired within a prolongation in measurement time by a factor of 1.5, leading to an SNR increase by approximately {radical}2. Furthermore it is demonstrated that the reversed gradient method remarkably reduces artifacts caused by a discontinuous k-space weighting. Assuming sequence parameters as feasible for fMRI experiments, artifact free T2{sup *}-weighted images with a matrix size of 256 x 256 leading to an in-plane resolution in the submillimeter range can be obtained in about 2 s per slice. (orig.)

  6. Diagnostic value of the fast-FLAIR sequence in MR imaging of intracranial tumors

    International Nuclear Information System (INIS)

    Husstedt, H.W.; Sickert, M.; Koestler, H.; Haubitz, B.; Becker, H.

    2000-01-01

    The aim of this study was to quantify imaging characteristics of fast fluid-attenuated inversion recovery (FLAIR) sequence in brain tumors compared with T1-postcontrast- and T2-sequences. Fast-FLAIR-, T2 fast spin echo (FSE)-, and T1 SE postcontrast images of 74 patients with intracranial neoplasms were analyzed. Four neuroradiologists rated signal intensity and inhomogeneity of the tumor, rendering of cystic parts, demarcation of the tumor vs brain, of the tumor vs edema and of brain vs edema, as well as the presence of motion and of other artifacts. Data analysis was performed for histologically proven astrocytomas, glioblastomas, and meningiomas, for tumors with poor contrast enhancement, and for all patients pooled. Only for tumors with poor contrast enhancement (n = 12) did fast FLAIR provide additional information about the lesion. In these cases, signal intensity, demarcation of the tumor vs brain, and differentiation of the tumor vs edema were best using fast FLAIR. In all cases, rendering of the tumor's inner structure was poor. For all other tumor types, fast FLAIR did not give clinically relevant information, the only exception being a better demarcation of the edema from brain tissue. Artifacts rarely interfered with evaluation of fast-FLAIR images. Thus, fast FLAIR cannot replace T2-weighted series. It provides additional information only in tumors with poor contrast enhancement. It is helpful for defining the exact extent of the edema of any tumor but gives little information about their inner structure. (orig.)

  7. Diagnostic value of the fast-FLAIR sequence in MR imaging of intracranial tumors.

    Science.gov (United States)

    Husstedt, H W; Sickert, M; Köstler, H; Haubitz, B; Becker, H

    2000-01-01

    The aim of this study was to quantify imaging characteristics of fast fluid-attenuated inversion recovery (FLAIR) sequence in brain tumors compared with T1-postcontrast- and T2-sequences. Fast-FLAIR-, T2 fast spin echo (FSE)-, and T1 SE postcontrast images of 74 patients with intracranial neoplasms were analyzed. Four neuroradiologists rated signal intensity and inhomogeneity of the tumor, rendering of cystic parts, demarcation of the tumor vs brain, of the tumor vs edema and of brain vs edema, as well as the presence of motion and of other artifacts. Data analysis was performed for histologically proven astrocytomas, glioblastomas, and meningiomas, for tumors with poor contrast enhancement, and for all patients pooled. Only for tumors with poor contrast enhancement (n = 12) did fast FLAIR provide additional information about the lesion. In these cases, signal intensity, demarcation of the tumor vs brain, and differentiation of the tumor vs edema were best using fast FLAIR. In all cases, rendering of the tumor's inner structure was poor. For all other tumor types, fast FLAIR did not give clinically relevant information, the only exception being a better demarcation of the edema from brain tissue. Artifacts rarely interfered with evaluation of fast-FLAIR images. Thus, fast FLAIR cannot replace T2-weighted series. It provides additional information only in tumors with poor contrast enhancement. It is helpful for defining the exact extent of the edema of any tumor but gives little information about their inner structure.

  8. Artifact free T2*-weighted imaging at high spatial resolution using segmented EPI sequences

    International Nuclear Information System (INIS)

    Heiler, Patrick Michael; Schad, Lothar Rudi; Schmitter, Sebastian

    2010-01-01

    The aim of this work was the development of novel measurement techniques that acquire high resolution T2 * -weighted datasets in measurement times as short as possible without suffering from noticeable blurring and ghosting artifacts. Therefore, two new measurement techniques were developed that acquire a smoother k-space than generic multi shot echo planar imaging sequences. One is based on the principle of echo train shifting, the other on the reversed gradient method. Simulations and phantom measurements demonstrate that echo train shifting works properly and reduces artifacts in multi shot echo planar imaging. For maximum SNR-efficiency this technique was further improved by adding a second contrast. Both contrasts can be acquired within a prolongation in measurement time by a factor of 1.5, leading to an SNR increase by approximately √2. Furthermore it is demonstrated that the reversed gradient method remarkably reduces artifacts caused by a discontinuous k-space weighting. Assuming sequence parameters as feasible for fMRI experiments, artifact free T2 * -weighted images with a matrix size of 256 x 256 leading to an in-plane resolution in the submillimeter range can be obtained in about 2 s per slice. (orig.)

  9. The cross-talk problem in SiPMs and their use as light sensors for imaging atmospheric Cherenkov telescopes

    International Nuclear Information System (INIS)

    Buzhan, P.; Dolgoshein, B.; Ilyin, A.; Kaplin, V.; Klemin, S.; Mirzoyan, R.; Popova, E.; Teshima, M.

    2009-01-01

    One of the major drawbacks of a SiPM is due to the so-called cross-talk effect. Often, one single photon in a chain reaction can generate more photons and thus can fire more than one micro-cell of a SiPM. This can be considered as a noise in the signal multiplication process and this degrades the signal/noise ratio. In self-trigger schemes this noise can be so high that it can make operating them difficult at low threshold settings. For the past few years, we have dwelt on this effect aiming to suppress it at the design stage. One can use (a) trenches around the micro-cells for suppressing the direct photon 'communication' channel and (b) the so-called double p-n junction for suppressing photon-induced charge 'communication' in neighbor pixels. The low cross-talk is mandatory, for example, for producing SiPM-based light sensor modules for the Imaging Atmospheric Cherenkov Technique projects for ground-based gamma-ray astrophysics. We produced and tested a few modules consisting of 4 SiPMs, each with a size of 5 mmx5 mm of custom production type. We report here on the main parameters of these units.

  10. Diuretic-enhanced gadolinium excretory MR urography: comparison of conventional gradient-echo sequences and echo-planar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Nolte-Ernsting, C.C.A.; Tacke, J.; Adam, G.B.; Haage, P.; Guenther, R.W. [Univ. of Technology, Aachen (Germany). Dept. of Diagnostic Radiology; Jung, P.; Jakse, G. [Univ. of Technology, Aachen (Germany). Dept. of Urology

    2001-01-01

    The aim of this study was to investigate the utility of different gadolinium-enhanced T1-weighted gradient-echo techniques in excretory MR urography. In 74 urologic patients, excretory MR urography was performed using various T1-weighted gradient-echo (GRE) sequences after injection of gadolinium-DTPA and low-dose furosemide. The examinations included conventional GRE sequences and echo-planar imaging (GRE EPI), both obtained with 3D data sets and 2D projection images. Breath-hold acquisition was used primarily. In 20 of 74 examinations, we compared breath-hold imaging with respiratory gating. Breath-hold imaging was significantly superior to respiratory gating for the visualization of pelvicaliceal systems, but not for the ureters. Complete MR urograms were obtained within 14-20 s using 3D GRE EPI sequences and in 20-30 s with conventional 3D GRE sequences. Ghost artefacts caused by ureteral peristalsis often occurred with conventional 3D GRE imaging and were almost completely suppressed in EPI sequences (p < 0.0001). Susceptibility effects were more pronounced on GRE EPI MR urograms and calculi measured 0.8-21.7% greater in diameter compared with conventional GRE sequences. Increased spatial resolution degraded the image quality only in GRE-EPI urograms. (orig.)

  11. Color Image Encryption Using Three-Dimensional Sine ICMIC Modulation Map and DNA Sequence Operations

    Science.gov (United States)

    Liu, Wenhao; Sun, Kehui; He, Yi; Yu, Mengyao

    Derived from Sine map and iterative chaotic map with infinite collapse (ICMIC), a three-dimensional hyperchaotic Sine ICMIC modulation map (3D-SIMM) is proposed based on a close-loop modulation coupling (CMC) method. Based on this map, a novel color image encryption algorithm is designed by employing a hybrid model of multidirectional circular permutation and deoxyribonucleic acid (DNA) masking. In this scheme, the pixel positions of image are scrambled by multidirectional circular permutation, and the pixel values are substituted by DNA sequence operations. The simulation results and security analysis show that the algorithm has good encryption effect and strong key sensitivity, and can resist brute-force, statistical, differential, known-plaintext and chosen-plaintext attacks.

  12. Imaging cardiac activation sequence during ventricular tachycardia in a canine model of nonischemic heart failure.

    Science.gov (United States)

    Han, Chengzong; Pogwizd, Steven M; Yu, Long; Zhou, Zhaoye; Killingsworth, Cheryl R; He, Bin

    2015-01-15

    Noninvasive cardiac activation imaging of ventricular tachycardia (VT) is important in the clinical diagnosis and treatment of arrhythmias in heart failure (HF) patients. This study investigated the ability of the three-dimensional cardiac electrical imaging (3DCEI) technique for characterizing the activation patterns of spontaneously occurring and norepinephrine (NE)-induced VTs in a newly developed arrhythmogenic canine model of nonischemic HF. HF was induced by aortic insufficiency followed by aortic constriction in three canines. Up to 128 body-surface ECGs were measured simultaneously with bipolar recordings from up to 232 intramural sites in a closed-chest condition. Data analysis was performed on the spontaneously occurring VTs (n=4) and the NE-induced nonsustained VTs (n=8) in HF canines. Both spontaneously occurring and NE-induced nonsustained VTs initiated by a focal mechanism primarily from the subendocardium, but occasionally from the subepicardium of left ventricle. Most focal initiation sites were located at apex, right ventricular outflow tract, and left lateral wall. The NE-induced VTs were longer, more rapid, and had more focal sites than the spontaneously occurring VTs. Good correlation was obtained between imaged activation sequence and direct measurements (averaged correlation coefficient of ∼0.70 over 135 VT beats). The reconstructed initiation sites were ∼10 mm from measured initiation sites, suggesting good localization in such a large animal model with cardiac size similar to a human. Both spontaneously occurring and NE-induced nonsustained VTs had focal initiation in this canine model of nonischemic HF. 3DCEI is feasible to image the activation sequence and help define arrhythmia mechanism of nonischemic HF-associated VTs. Copyright © 2015 the American Physiological Society.

  13. Digital Sequences and a Time Reversal-Based Impact Region Imaging and Localization Method

    Science.gov (United States)

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Qian, Weifeng

    2013-01-01

    To reduce time and cost of damage inspection, on-line impact monitoring of aircraft composite structures is needed. A digital monitor based on an array of piezoelectric transducers (PZTs) is developed to record the impact region of impacts on-line. It is small in size, lightweight and has low power consumption, but there are two problems with the impact alarm region localization method of the digital monitor at the current stage. The first one is that the accuracy rate of the impact alarm region localization is low, especially on complex composite structures. The second problem is that the area of impact alarm region is large when a large scale structure is monitored and the number of PZTs is limited which increases the time and cost of damage inspections. To solve the two problems, an impact alarm region imaging and localization method based on digital sequences and time reversal is proposed. In this method, the frequency band of impact response signals is estimated based on the digital sequences first. Then, characteristic signals of impact response signals are constructed by sinusoidal modulation signals. Finally, the phase synthesis time reversal impact imaging method is adopted to obtain the impact region image. Depending on the image, an error ellipse is generated to give out the final impact alarm region. A validation experiment is implemented on a complex composite wing box of a real aircraft. The validation results show that the accuracy rate of impact alarm region localization is approximately 100%. The area of impact alarm region can be reduced and the number of PZTs needed to cover the same impact monitoring region is reduced by more than a half. PMID:24084123

  14. Comparison of single-shot fast spin-echo sequence and T2-weighted fast spin-echo sequence in MR imaging of the brain

    International Nuclear Information System (INIS)

    Cha, Sung Ho; Seo, Jeong Jin; Jeong, Gwang Woo; Kim, Jae Kyu; Kim, Yun Hyeon; Jeong, Yong Yeon; Kang, Heoung Keun; Oh, Hee Yeon; Yoon, Jong Hoon

    1998-01-01

    The purpose of this study was to evaluate the usefulness of the single-shot fast spinecho (SS-FSE) sequence in comparison with the T2-weighted fast spin-echo (T2-FSE) sequence in brain MR imaging. In 41 patients aged 15-75 years with intracranial lesion, both SS-FSE and T2-FES images were obtained using a 1.5-T MR system. Lesions included cerebral ischemia or infarcts (n=3D23), tumors (n=3D10), hemorrhages (n=3D3), inflammatory diseases (n=3D2), arachnoid cysts(n=3D2), and vascular disease (n=3D1), and the MR images were retrospectively evaluated. To calculate contrast-to-noise ratio (CNR), percentage contrast, and signal-to-noise ratio (SNR)-and thus make a quantitative comparison-the mean signal intensities of lesions, normal brain tissue, and noise out-side the patient were measured. For qualitative comparison, the visibility, margin, and extent of the lesions were rated using a five-grade system, and the degree of MR artifacts was also evaluated. Wilcoxon's signed ranks test was used for statistical analysis. The mean CNR of lesions was significantly higher on SS-FSE (31.3) than on T2-FSE images (27.5) (p=3D0.0131). Mean percentage contrast was also higher on SS-FSE (159.0) than on T2-FSE images (108.5) (p=3D0.0222), but mean SNR was higher on T2-FSE (80.3) than on SS-FSE images (53.5) (p=3D0.0000). No significant differences in lesion visibility were observed between the two imaging sequences, though margin and extent of the lesion were worse on SS-FSE images. For MR artifacts, no significant differences were demonstrated. For the evaluation of most intracranial lesions, MR imaging using the SS-FSE sequence appears to be slightly inferior to the T2-FSE sequence, but may be useful where patients are ill or uncooperative, or where children require sedation.=20

  15. SPIO-enhanced MR imaging for HCC detection in cirrhotic patient : comparison of various techniques for optimal sequence selection

    International Nuclear Information System (INIS)

    Kim, In Hwan; Lee, Jeong Min; Kwak, Hyo Sung; Kim, Chong Soo; Yu, Hee Chul; Kim, Tae Kon; Lee Soo Tiek

    2000-01-01

    To compare the efficacy of breathhold and non-breathhold sequences in the detection of hepatocellular carcinoma (HCC) in cirrhotic patients using superparamagnetic iron oxide (SPIO)-enhanced MR imaging, and to determine the optimal sequence combination. By means of unenhanced and iron-oxide-enhanced MRI, 29 patients with 49 nodular HCCs were evaluated for the presence of HCC nodules. Twenty-one were male and eight were female, and their ages ranged from 38 to 71 (mean, 56) years. Eight different MR sequences were used, including four non-breath-hold sequences and four breath-hold, and images were obtained before and after the administration of SPIO particles. Non-breath-hold sequences included T2-, proton density-weighted SE, and TSE imaging, while breath-hold sequences comprised T1-weighted fast low-angle shot (T1w FLASH), half-Fourier acquisition single shot turbo spine echo (HASTE), T2-weighted fast imaging with steady-state free precession (T2 * wFISP) and T2-weighted breath-hold TSE (T2wBHTSE). Image analysis involved both quantitative and qualitative analysis. The quantitative parameters calculated were signal-to noise (S/N) ratios for livers and tumors, contrast to noise (C/N) ratios for tumors seen on precontrast and postcontrast images, and percentage of signal intensity loss (PSIL) after SPIO injection. Images were analysed qualitatively in terms of image artifacts and lesion conspicuity, and prior to calculating sensitivity, the number of lesions detected using various pulse sequences were counted. SPIO had a marked effect on liver S/N ratio but a minimal effect on tumor S/N ratio. PSIL was best in T2 * wFISP images, while T2wSE images showed the second-best results (p less than 0.05). Tumor-to-liver C/N values were also highest with T2 * wFISP, while T2wTSE and HASTE images were next. Qualitative study showed that non-breath hold images and FISP were better than breath hold images in terms of lesion conspicuity. The latter, however, were much better

  16. On the Usage of GPUs for Efficient Motion Estimation in Medical Image Sequences

    Directory of Open Access Journals (Sweden)

    Jeyarajan Thiyagalingam

    2011-01-01

    Full Text Available Images are ubiquitous in biomedical applications from basic research to clinical practice. With the rapid increase in resolution, dimensionality of the images and the need for real-time performance in many applications, computational requirements demand proper exploitation of multicore architectures. Towards this, GPU-specific implementations of image analysis algorithms are particularly promising. In this paper, we investigate the mapping of an enhanced motion estimation algorithm to novel GPU-specific architectures, the resulting challenges and benefits therein. Using a database of three-dimensional image sequences, we show that the mapping leads to substantial performance gains, up to a factor of 60, and can provide near-real-time experience. We also show how architectural peculiarities of these devices can be best exploited in the benefit of algorithms, most specifically for addressing the challenges related to their access patterns and different memory configurations. Finally, we evaluate the performance of the algorithm on three different GPU architectures and perform a comprehensive analysis of the results.

  17. Exploring the effects of gravity on tongue motion using ultrasound image sequences

    Science.gov (United States)

    Stone, Maureen; Crouse, Ulla; Sutton, Marty

    2002-05-01

    Our goal in the research was to explore the effect that gravity had on the vocal-tract system by using ultrasound data collected in the upright and supine positions. All potential subjects were given an ultrasound pretest to determine whether they could repeat a series of 3-4 words precise enough to allow an accurate series of images to be collected. Out of these potential subjects, approximately 5-7 subjects were eventually used in the research. The method of collecting ultrasound data required the immobilization of the patient by restraining their neck in a custom fitted neck restraint. The neck restraint held an ultrasound transducer positioned at a critical angle underneath the patients' lower jawbone, which served to reduce errors and increase image resolution. To accurately analyze the series of images collected from ultrasound imaging, the surfaces of the tongue were digitized and tongue motion was time-aligned across the upright and supine sequences. Comparisons between the upright and supine data were then made by using L2 norms to determine averages and differences regarding the behavior between the two positions. Curves and locations of the maximum and minimum differences will be discussed.

  18. A Low-Complexity Algorithm for Static Background Estimation from Cluttered Image Sequences in Surveillance Contexts

    Directory of Open Access Journals (Sweden)

    Reddy Vikas

    2011-01-01

    Full Text Available Abstract For the purposes of foreground estimation, the true background model is unavailable in many practical circumstances and needs to be estimated from cluttered image sequences. We propose a sequential technique for static background estimation in such conditions, with low computational and memory requirements. Image sequences are analysed on a block-by-block basis. For each block location a representative set is maintained which contains distinct blocks obtained along its temporal line. The background estimation is carried out in a Markov Random Field framework, where the optimal labelling solution is computed using iterated conditional modes. The clique potentials are computed based on the combined frequency response of the candidate block and its neighbourhood. It is assumed that the most appropriate block results in the smoothest response, indirectly enforcing the spatial continuity of structures within a scene. Experiments on real-life surveillance videos demonstrate that the proposed method obtains considerably better background estimates (both qualitatively and quantitatively than median filtering and the recently proposed "intervals of stable intensity" method. Further experiments on the Wallflower dataset suggest that the combination of the proposed method with a foreground segmentation algorithm results in improved foreground segmentation.

  19. Coseismic deformation pattern of the Emilia 2012 seismic sequence imaged by Radarsat-1 interferometry

    Directory of Open Access Journals (Sweden)

    Christian Bignami

    2012-10-01

    Full Text Available On May 20 and 29, 2012, two earthquakes of magnitudes 5.9 and 5.8 (Mw, respectively, and their aftershock sequences hit the central Po Plain (Italy, about 40 km north of Bologna. More than 2,000 sizable aftershocks were recorded by the Isti-tuto Nazionale di Geofisica e Vulcanologia (INGV; National Institute of Geophysics and Volcanology National Seismic Network (http://iside.rm.ingv.it/. The sequence was generated by pure compressional faulting over blind thrusts of the western Ferrara Arc, and it involved a 50-km-long stretch of this buried outer front of the northern Apennines. The focal mechanisms of the larger shocks agree with available structural data and with present-day tectonic stress indicators, which show locally a maximum horizontal stress oriented ca. N-S; i.e. oriented perpendicular to the main structural trends. Most of the sequence occurred between 1 km and 12 km in depth, above the local basal detachment of the outer thrust fronts of the northern Apennines. We measured the surface displacement patterns associated with the mainshocks and some of the larger aftershocks (some of which had Mw >5.0 by applying the Interferometric Synthetic Aperture Radar (InSAR technique to a pair of C-Band Radarsat-1 images. We then used the coseismic motions detected over the epicentral region as input information, to obtain the best-fit model fault for the two largest shocks. […

  20. A probabilistic cell model in background corrected image sequences for single cell analysis

    Directory of Open Access Journals (Sweden)

    Fieguth Paul

    2010-10-01

    Full Text Available Abstract Background Methods of manual cell localization and outlining are so onerous that automated tracking methods would seem mandatory for handling huge image sequences, nevertheless manual tracking is, astonishingly, still widely practiced in areas such as cell biology which are outside the influence of most image processing research. The goal of our research is to address this gap by developing automated methods of cell tracking, localization, and segmentation. Since even an optimal frame-to-frame association method cannot compensate and recover from poor detection, it is clear that the quality of cell tracking depends on the quality of cell detection within each frame. Methods Cell detection performs poorly where the background is not uniform and includes temporal illumination variations, spatial non-uniformities, and stationary objects such as well boundaries (which confine the cells under study. To improve cell detection, the signal to noise ratio of the input image can be increased via accurate background estimation. In this paper we investigate background estimation, for the purpose of cell detection. We propose a cell model and a method for background estimation, driven by the proposed cell model, such that well structure can be identified, and explicitly rejected, when estimating the background. Results The resulting background-removed images have fewer artifacts and allow cells to be localized and detected more reliably. The experimental results generated by applying the proposed method to different Hematopoietic Stem Cell (HSC image sequences are quite promising. Conclusion The understanding of cell behavior relies on precise information about the temporal dynamics and spatial distribution of cells. Such information may play a key role in disease research and regenerative medicine, so automated methods for observation and measurement of cells from microscopic images are in high demand. The proposed method in this paper is capable

  1. Diffusion-weighted imaging of the rat pelvis using 3D water-excitation MP-RAGE MR sequence

    International Nuclear Information System (INIS)

    Numano, Tomokazu; Homma, Kazuhiro; Hyodo, Koji; Nitta, Naotaka; Iwasaki, Nobuaki

    2008-01-01

    We developed a novel technique for fat-saturated, 3-dimensional (3D) diffusion-weighted (DW) magnetic resonance (MR) imaging sequencing based upon the 3D magnetization-prepared, rapid gradient-echo (3D-MP-RAGE) method. We saturated fat using 2 techniques, chemical shift selective (CHESS; FatSat)-3D-DWI sequence versus water excitation (WE)-3D-DWI method, then compared the 2 sequences in terms of degree of fat suppression. In preparing the FatSat-3D-DWI sequence, we used a ''CHESS-90deg radiofrequency (RF)-motion probing gradient (MPG)-180deg RFMPG-90deg RF'' pulse-train, to sensitize the magnetization to fat-saturated diffusion. In contrast, in the WE-3D-DWI sequence, we selected a RAGE-excitation pulse with a binominal-pulse 1-1 or 1-2-1 for water-excited (fat-saturated) diffusion imaging. Experimental results in a phantom confirmed the effects of diffusion weighting and of fat saturation. Fat saturation was much better in the WE-3D-DWI sequence than the CHESS-3D-DWI sequence. From results from animal (rat pelvis) experiments using WE-3D-DWI, we obtained fat-saturated DWI. This sequence was useful for in vivo imaging. (author)

  2. Generalized min-max bound-based MRI pulse sequence design framework for wide-range T1 relaxometry: A case study on the tissue specific imaging sequence.

    Directory of Open Access Journals (Sweden)

    Yang Liu

    Full Text Available This paper proposes a new design strategy for optimizing MRI pulse sequences for T1 relaxometry. The design strategy optimizes the pulse sequence parameters to minimize the maximum variance of unbiased T1 estimates over a range of T1 values using the Cramér-Rao bound. In contrast to prior sequences optimized for a single nominal T1 value, the optimized sequence using our bound-based strategy achieves improved precision and accuracy for a broad range of T1 estimates within a clinically feasible scan time. The optimization combines the downhill simplex method with a simulated annealing process. To show the effectiveness of the proposed strategy, we optimize the tissue specific imaging (TSI sequence. Preliminary Monte Carlo simulations demonstrate that the optimized TSI sequence yields improved precision and accuracy over the popular driven-equilibrium single-pulse observation of T1 (DESPOT1 approach for normal brain tissues (estimated T1 700-2000 ms at 3.0T. The relative mean estimation error (MSE for T1 estimation is less than 1.7% using the optimized TSI sequence, as opposed to less than 7.0% using DESPOT1 for normal brain tissues. The optimized TSI sequence achieves good stability by keeping the MSE under 7.0% over larger T1 values corresponding to different lesion tissues and the cerebrospinal fluid (up to 5000 ms. The T1 estimation accuracy using the new pulse sequence also shows improvement, which is more pronounced in low SNR scenarios.

  3. Research on the Compression Algorithm of the Infrared Thermal Image Sequence Based on Differential Evolution and Double Exponential Decay Model

    Science.gov (United States)

    Zhang, Jin-Yu; Meng, Xiang-Bing; Xu, Wei; Zhang, Wei; Zhang, Yong

    2014-01-01

    This paper has proposed a new thermal wave image sequence compression algorithm by combining double exponential decay fitting model and differential evolution algorithm. This study benchmarked fitting compression results and precision of the proposed method was benchmarked to that of the traditional methods via experiment; it investigated the fitting compression performance under the long time series and improved model and validated the algorithm by practical thermal image sequence compression and reconstruction. The results show that the proposed algorithm is a fast and highly precise infrared image data processing method. PMID:24696649

  4. Research on the Compression Algorithm of the Infrared Thermal Image Sequence Based on Differential Evolution and Double Exponential Decay Model

    Directory of Open Access Journals (Sweden)

    Jin-Yu Zhang

    2014-01-01

    Full Text Available This paper has proposed a new thermal wave image sequence compression algorithm by combining double exponential decay fitting model and differential evolution algorithm. This study benchmarked fitting compression results and precision of the proposed method was benchmarked to that of the traditional methods via experiment; it investigated the fitting compression performance under the long time series and improved model and validated the algorithm by practical thermal image sequence compression and reconstruction. The results show that the proposed algorithm is a fast and highly precise infrared image data processing method.

  5. Turbo-Proton Echo Planar Spectroscopic Imaging (t-PEPSI) MR technique in the detection of diffuse axonal damage in brain injury. Comparison with Gradient-Recalled Echo (GRE) sequence.

    Science.gov (United States)

    Giugni, E; Sabatini, U; Hagberg, G E; Formisano, R; Castriota-Scanderbeg, A

    2005-01-01

    Diffuse axonal injury (DAI) is a common type of primary neuronal injury in patients with severe traumatic brain injury, and is frequently accompanied by tissue tear haemorrhage. The T2*-weighted gradient-recalled echo (GRE) sequences are more sensitive than T2-weighted spin-echo images for detection of haemorrhage. This study was undertaken to determine whether turbo-PEPSI, an extremely fast multi-echo-planar-imaging sequence, can be used as an alternative to the GRE sequence for detection of DAI. Nineteen patients (mean age 24,5 year) with severe traumatic brain injury (TBI), occurred at least 3 months earlier, underwent a brain MRI study on a 1.5-Tesla scanner. A qualitative evaluation of the turbo-PEPSI sequences was performed by identifying the optimal echo time and in-plane resolution. The number and size of DAI lesions, as well as the signal intensity contrast ratio (SI CR), were computed for each set of GRE and turbo-PEPSI images, and divided according to their anatomic location into lobar and/or deep brain. There was no significant difference between GRE and turbo-PEPSI sequences in the total number of DAI lesions detected (283 vs 225 lesions, respectively). The GRE sequence identified a greater number of hypointense lesions in the temporal lobe compared to the t-PEPSI sequence (72 vs 35, pPEPSI than for the GRE sequence (pPEPSI sequence can be used as an alternative to the GRE to assess brain DAI in severe TBI patients, especially if uncooperative and medically unstable.

  6. Breakdown voltage mapping through voltage dependent ReBEL intensity imaging of multi-crystalline Si solar cells

    Science.gov (United States)

    Dix-Peek, RM.; van Dyk, EE.; Vorster, FJ.; Pretorius, CJ.

    2018-04-01

    Device material quality affects both the efficiency and the longevity of photovoltaic (PV) cells. Therefore, identifying these defects can be beneficial in the development of more efficient and longer lasting PV cells. In this study, a combination of spatially-resolved, electroluminescence (EL), and light beam induced current (LBIC) measurements, were used to identify specific defects and features of a multi-crystalline Si PV cells. In this study, a novel approach is used to map the breakdown voltage of a PV cell through voltage dependent Reverse Bias EL (ReBEL) intensity imaging.

  7. The Stellar Imager (SI) Project: A Deep Space UV/Optical Interferometer (UVOI) to Observe the Universe at 0.1 Milli-Arcsec Angular Resolution

    Science.gov (United States)

    Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita

    2008-01-01

    The Stellar Imager (SI) is a space-based, UV/ Optical Interferometer (UVOI) designed to enable 0.1 milliarcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general. It will also probe via asteroseismology flows and structures in stellar interiors. SI's science focuses on the role of magnetism in the Universe and will revolutionize our understanding, of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes, such as accretion, in the Universe. The ultra-sharp images of SI will revolutionize our view of many dynamic astrophysical processes by transforming point sources into extended sources, and snapshots into evolving views. SI is a "Flagship and Landmark Discovery Mission" in the 2005 Heliophysics Roadmap and a potential implementation of the UVOI in the 2006 Science Program for NASA's Astronomy and Physics Division. We present here the science goals of the SI Mission, a mission architecture that could meet those goals, and the technology development needed to enable this missin. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/.

  8. Photoelectron Diffraction Imaging for C2H2 and C2H4 Chemisorbed on Si(100) Reveals a New Bonding Configuration

    International Nuclear Information System (INIS)

    Xu, S. H.; Keeffe, M.; Yang, Y.; Chen, C.; Yu, M.; Lapeyre, G. J.; Rotenberg, E.; Denlinger, J.; Yates, J. T. Jr.

    2000-01-01

    A new adsorption site for adsorbed acetylene on Si(100) is observed by photoelectron imaging based on the holographic principle. The diffraction effects in the carbon 1s angle-resolved photoemission are inverted (including the small-cone method) to obtain an image of the atom's neighboring carbon. The chemisorbed acetylene molecule is bonded to four silicon surface atoms. In contrast to the C 2 H 2 case, the image for adsorbed C 2 H 4 shows it bonded to two Si surface atoms. (c) 2000 The American Physical Society

  9. Detection of hepatic VX2 carcinomas with ferucarbotran-enhanced magnetic resonance imaging in rabbits: Comparison of nine pulse sequences

    International Nuclear Information System (INIS)

    Kim, Seong Hyun; Choi, Dongil; Lim, Hyo K.; Kim, Min Ju; Jang, Kyung Mi; Kim, Seung Hoon; Lee, Won Jae; Lee, Jongmee; Jeon, Yong Hwan; Lim, Jae Hoon

    2006-01-01

    Objective: To compare the diagnostic performance of a variety of magnetic resonance imaging (MRI) sequences, in order to identify the most effective ferucarbotran-enhanced sequence for the detection of multiple small hepatic VX2 carcinomas in rabbits. Methods: Fifteen rabbits with experimentally induced 135 VX2 carcinomas in the liver underwent ferucarbotran-enhanced MRI using the following nine pulse sequences: a fat-suppressed fast spin-echo (FSE) sequence with two echo times (TE) (proton density- and T2-weighted images), four different T2*-weighted fast multiplanar GRASS (gradient-recalled acquisition in the steady state) (FMPGR) with the combination of three TEs (9, 12, 15 ms, respectively) and two flip angles (20 deg., 80 deg., respectively), T2*-weighted fast multiplanar spoiled GRASS (FMPSPGR), T1-weighted FMPSPGR, and dynamic T1-weighted FMPSPGR. All images were reviewed by three radiologists with quantitative and qualitative analysis. Results: Tumor-to-liver contrast-to-noise ratio of the proton density-weighted FSE sequence was significantly higher than those of the others (p o ) images were superior to those of the others and for the detection of very small hepatic tumors of less than 5 mm, the sensitivities of these sequences were less than 30%. Conclusion: Ferucarbotran-enhanced T2- and proton density-weighted FSE and T2*-weighed FMPGR (TE/flip angle, 12/20 o ) images were found to be the most effective pulse sequences for the detection of multiple small hepatic VX2 carcinomas but these sequences were limited in the detection of very small hepatic tumors of less than 5 mm in size

  10. [Contrastive analysis of artifacts produced by metal dental crowns in 3.0 T magnetic resonance imaging with six sequences].

    Science.gov (United States)

    Lan, Gao; Yunmin, Lian; Pu, Wang; Haili, Huai

    2016-06-01

    This study aimed to observe and evaluate six 3.0 T sequences of metallic artifacts produced by metal dental crowns. Dental crowns fabricated with four different materials (Co-Gr, Ni-Gr, Ti alloy and pure Ti) were evaluated. A mature crossbreed dog was used as the experimental animal, and crowns were fabricated for its upper right second premolar. Each crown was examined through head MRI (3.0 T) with six sequences, namely, T₁ weighted-imaging of spin echo (T₁W/SE), T₂ weighted-imaging of inversion recovery (T₂W/IR), T₂ star gradient echo (T₂*/GRE), T2 weighted-imaging of fast spin echo (T₂W/FSE), T₁ weighted-imaging of fluid attenuate inversion recovery (T₂W/FLAIR), and T₂ weighted-imaging of propeller (T₂W/PROP). The largest area and layers of artifacts were assessed and compared. The artifact in the T₂*/GRE sequence was significantly wider than those in the other sequences (P 0.05). T₂*/GRE exhibit the strongest influence on the artifact, whereas the five other sequences contribute equally to artifact generation.

  11. SU-E-J-216: A Sequence Independent Approach for Quantification of MR Image Deformations From Brachytherapy Applicators

    Energy Technology Data Exchange (ETDEWEB)

    Wieringen, N van; Heerden, L van; Gurney-Champion, O; Kesteren, Z van; Houweling, A; Pieters, B; Bel, A [Academic Medical Center, Amsterdam (Netherlands)

    2015-06-15

    Purpose: MRI is increasingly used as a single imaging modality for brachytherapy treatment planning. The presence of a brachytherapy applicator may cause distortions in the images, especially at higher field strengths. Our aim is to develop a procedure to quantify these distortions theoretically for any MR-sequence and to verify the estimated deformations for clinical sequences. Methods: Image distortions due to perturbation of the B0-field are proportional to the ratio of the induced frequency shift and the read-out bandwidth of the applied sequence. By reconstructing a frequency-shift map from the phase data from a multi-echo sequence, distortions can be calculated for any MR-sequence. Verification of this method for estimating distortions was performed by acquiring images with opposing read-out directions and consequently opposing distortions. The applicator shift can be determined by rigidly matching these images. Clinically, T2W-TSE-images are used for this purpose. For pre-clinical tests, EPI-sequences with narrow read-out bandwidth (19.5–47.5Hz), consequently large distortions, were added to the set of clinical MRsequences. To quantify deformations of the Utrecht Interstitial CT/MR applicator (Elekta Brachytherapy) on a Philips Ingenia 3T MRI, pre-clinical tests were performed in a phantom with the applicator in water, followed by clinical validation. Results: Deformations observed in the narrow bandwidth EPI-images were well predicted using the frequency-shift, the latter giving an overestimation up to 30%/up to 1 voxel. For clinically applied MR-sequences distortions were well below the voxel size. In patient setup distortions determined from the frequency-shift map were at sub-voxel level (<0.7mm). Using T2W-images larger distortions were found (1–2mm). This discrepancy was caused by patient movement between/during acquisition of the T2W-images with opposing read-out directions. Conclusion: Phantom experiments demonstrated the feasibility of a

  12. Evaluation of Magnetic Resonance Imaging-Compatible Needles and Interactive Sequences for Musculoskeletal Interventions Using an Open High-Field Magnetic Resonance Imaging Scanner

    International Nuclear Information System (INIS)

    Wonneberger, Uta; Schnackenburg, Bernhard; Streitparth, Florian; Walter, Thula; Rump, Jens; Teichgraeber, Ulf K. M.

    2010-01-01

    In this article, we study in vitro evaluation of needle artefacts and image quality for musculoskeletal laser-interventions in an open high-field magnetic resonance imaging (MRI) scanner at 1.0T with vertical field orientation. Five commercially available MRI-compatible puncture needles were assessed based on artefact characteristics in a CuSO4 phantom (0.1%) and in human cadaveric lumbar spines. First, six different interventional sequences were evaluated with varying needle orientation to the main magnetic field B0 (0 o to 90 o ) in a sequence test. Artefact width, needle-tip error, and contrast-to-noise ratio (CNR) were calculated. Second, a gradient-echo sequence used for thermometric monitoring was assessed and in varying echo times, artefact width, tip error, and signal-to-noise ratio (SNR) were measured. Artefact width and needle-tip error correlated with needle material, instrument orientation to B0, and sequence type. Fast spin-echo sequences produced the smallest needle artefacts for all needles, except for the carbon fibre needle (width o to B0. Overall, the proton density-weighted spin-echo sequences had the best CNR (CNR Muscle/Needle >16.8). Concerning the thermometric gradient echo sequence, artefacts remained <5 mm, and the SNR reached its maximum at an echo time of 15 ms. If needle materials and sequences are accordingly combined, guidance and monitoring of musculoskeletal laser interventions may be feasible in a vertical magnetic field at 1.0T.

  13. Immersion cooling of silicon photomultipliers (SiPM) for nuclear medicine imaging applications

    International Nuclear Information System (INIS)

    Raylman, R.R.; Stolin, A.V.

    2016-01-01

    Silicon photomultipliers (SiPM) are compact, high amplification light detection devices that have recently been incorporated into magnetic field-compatible positron emission tomography (PET) scanners. To take full advantage of these devices, it is preferable to cool them below room temperature. Most current methods are limited to the cooling of individual detector modules, increasing complexity and cost of scanners made-up of a large number of modules. In this work we investigated a new method of cooling, immersion of the detector modules in non-electrically conductive, cooled liquid. A small-scale prototype system was constructed to cool a relatively large area SiPM-based, scintillator detector module by immersing it in a circulating bath of mineral oil. Testing demonstrated that the system rapidly decreased and stabilized the temperature of the device. Operation of the detector illustrated the expected benefits of cooling, with no apparent degradation of performance attributable to immersion in fluid. - Highlights: • Immersion cooling is new, simple and inexpensive method to cool solid state based nuclear medicine scanner. • Method successfully tested on a scaled version of an SiPM-based PET detector module. • Can be scaled up to cool a complete PET scanner.

  14. Optic disc boundary segmentation from diffeomorphic demons registration of monocular fundus image sequences versus 3D visualization of stereo fundus image pairs for automated early stage glaucoma assessment

    Science.gov (United States)

    Gatti, Vijay; Hill, Jason; Mitra, Sunanda; Nutter, Brian

    2014-03-01

    Despite the current availability in resource-rich regions of advanced technologies in scanning and 3-D imaging in current ophthalmology practice, world-wide screening tests for early detection and progression of glaucoma still consist of a variety of simple tools, including fundus image-based parameters such as CDR (cup to disc diameter ratio) and CAR (cup to disc area ratio), especially in resource -poor regions. Reliable automated computation of the relevant parameters from fundus image sequences requires robust non-rigid registration and segmentation techniques. Recent research work demonstrated that proper non-rigid registration of multi-view monocular fundus image sequences could result in acceptable segmentation of cup boundaries for automated computation of CAR and CDR. This research work introduces a composite diffeomorphic demons registration algorithm for segmentation of cup boundaries from a sequence of monocular images and compares the resulting CAR and CDR values with those computed manually by experts and from 3-D visualization of stereo pairs. Our preliminary results show that the automated computation of CDR and CAR from composite diffeomorphic segmentation of monocular image sequences yield values comparable with those from the other two techniques and thus may provide global healthcare with a cost-effective yet accurate tool for management of glaucoma in its early stage.

  15. Robust Small Target Co-Detection from Airborne Infrared Image Sequences.

    Science.gov (United States)

    Gao, Jingli; Wen, Chenglin; Liu, Meiqin

    2017-09-29

    In this paper, a novel infrared target co-detection model combining the self-correlation features of backgrounds and the commonality features of targets in the spatio-temporal domain is proposed to detect small targets in a sequence of infrared images with complex backgrounds. Firstly, a dense target extraction model based on nonlinear weights is proposed, which can better suppress background of images and enhance small targets than weights of singular values. Secondly, a sparse target extraction model based on entry-wise weighted robust principal component analysis is proposed. The entry-wise weight adaptively incorporates structural prior in terms of local weighted entropy, thus, it can extract real targets accurately and suppress background clutters efficiently. Finally, the commonality of targets in the spatio-temporal domain are used to construct target refinement model for false alarms suppression and target confirmation. Since real targets could appear in both of the dense and sparse reconstruction maps of a single frame, and form trajectories after tracklet association of consecutive frames, the location correlation of the dense and sparse reconstruction maps for a single frame and tracklet association of the location correlation maps for successive frames have strong ability to discriminate between small targets and background clutters. Experimental results demonstrate that the proposed small target co-detection method can not only suppress background clutters effectively, but also detect targets accurately even if with target-like interference.

  16. The Stellar Imager (SI) project: a deep space UV/Optical Interferometer (UVOI) to observe the Universe at 0.1 milli-arcsec angular resolution

    Science.gov (United States)

    Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita

    2009-04-01

    The Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general. It will also probe via asteroseismology flows and structures in stellar interiors. SI’s science focuses on the role of magnetism in the Universe and will revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes, such as accretion, in the Universe. The ultra-sharp images of SI will revolutionize our view of many dynamic astrophysical processes by transforming point sources into extended sources, and snapshots into evolving views. SI is a “Flagship and Landmark Discovery Mission” in the 2005 Heliophysics Roadmap and a potential implementation of the UVOI in the 2006 Science Program for NASA’s Astronomy and Physics Division. We present here the science goals of the SI Mission, a mission architecture that could meet those goals, and the technology development needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/

  17. Activatable Optical Imaging with a Silica-Rhodamine Based Near Infrared (SiR700) Fluorophore: A comparison with cyanine based dyes

    Science.gov (United States)

    McCann, Thomas E.; Kosaka, Nobuyuki; Koide, Yuichiro; Mitsunaga, Makoto; Choyke, Peter L.; Nagano, Tetsuo; Urano, Yasuteru; Kobayashi, Hisataka

    2011-01-01

    Optical imaging is emerging as an important tool to visualize tumors. However, there are many potential choices among the available fluorophores. Optical imaging probes that emit in the visible range can image superficial tumors with high quantum yields, however, if deeper imaging is needed then near infrared (NIR) fluorophores are necessary. Most commercially available NIR fluorophores are cyanine based and are prone to non-specific binding and relatively limited photostability. Silica-containing rhodamine (SiR) fluorophores represent a new class of NIR fluorophores, which permit photoactivation via H-dimer formation as well as demonstrate improved photostability. This permits higher tumor-to-background ratios (TBRs) to be achieved over longer periods of time. Here, we compared an avidin conjugated with SiR700 (Av-SiR700) to similar compounds based on cyanine dyes (Av-Cy5.5 and Av-Alexa Fluor 680) in a mouse tumor model of ovarian cancer metastasis. We found that the Av-SiR700 probe demonstrated superior quenching enabling activation after binding-internalization to the target cell. As a result, Av-SiR700 had higher TBRs compared to Av-Cy5.5, and better biostability compared to Av-Alexa Fluor 680. PMID:22034863

  18. Assessment of myocardial infarction in mice by Late Gadolinium Enhancement MR imaging using an inversion recovery pulse sequence at 9.4T

    Directory of Open Access Journals (Sweden)

    Herlihy Amy H

    2008-01-01

    Full Text Available Abstract Purpose To demonstrate the feasibility of using an inversion recovery pulse sequence and to define the optimal inversion time (TI to assess myocardial infarction in mice by late gadolinium enhancement (LGE MRI at 9.4T, and to obtain the maximal contrast between the infarcted and the viable myocardium. Methods MRI was performed at 9.4T in mice, two days after induction of myocardial infarction (n = 4. For cardiovascular MR imaging, a segmented magnetization-prepared fast low angle shot (MP-FLASH sequence was used with varied TIs ranging from 40 to 420 ms following administration of gadolinium-DTPA at 0.6 mmol/kg. Contrast-to-noise (CNR and signal-to-noise ratio (SNR were measured and compared for each myocardial region of interest (ROI. Results The optimal TI, which corresponded to a minimum SNR in the normal myocardium, was 268 ms ± 27.3. The SNR in the viable myocardium was significantly different from that found in the infarcted myocardium (17.2 ± 2.4 vs 82.1 ± 10.8; p = 0.006 leading to a maximal relative SI (Signal Intensity between those two areas (344.9 ± 60.4. Conclusion Despite the rapid heart rate in mice, our study demonstrates that LGE MRI can be performed at 9.4T using a protocol similar to the one used for clinical MR diagnosis of myocardial infarction.

  19. Design and fabrication of Si-HDPE hybrid Fresnel lenses for infrared imaging systems.

    Science.gov (United States)

    Manaf, Ahmad Rosli Abdul; Sugiyama, Tsunetoshi; Yan, Jiwang

    2017-01-23

    In this work, novel hybrid Fresnel lenses for infrared (IR) optical applications were designed and fabricated. The Fresnel structures were replicated from an ultraprecision diamond-turned aluminum mold to an extremely thin layer (tens of microns) of high-density polyethylene polymer, which was directly bonded onto a flat single-crystal silicon wafer by press molding without using adhesives. Night mode imaging results showed that the fabricated lenses were able to visualize objects in dark fields with acceptable image quality. The capability of the lenses for thermography imaging was also demonstrated. This research provides a cost-effective method for fabricating ultrathin IR optical components.

  20. The Optimization of Magnetic Resonance Imaging Pulse Sequences in Order to Better Detection of Multiple Sclerosis Plaques.

    Science.gov (United States)

    Farshidfar, Z; Faeghi, F; Haghighatkhah, H R; Abdolmohammadi, J

    2017-09-01

    Magnetic resonance imaging (MRI) is the most sensitive technique to detect multiple sclerosis (MS) plaques in central nervous system. In some cases, the patients who were suspected to MS, Whereas MRI images are normal, but whether patients don't have MS plaques or MRI images are not enough optimized enough in order to show MS plaques? The aim of the current study is evaluating the efficiency of different MRI sequences in order to better detection of MS plaques. In this cross-sectional study which was performed at Shohada-E Tajrish in Tehran - Iran hospital between October, 2011 to April, 2012, included 20 patients who suspected to MS disease were selected by the method of random sampling and underwent routine brain Pulse sequences (Axial T2w, Axial T1w, Coronal T2w, Sagittal T1w, Axial FLAIR) by Siemens, Avanto, 1.5 Tesla system. If any lesion which is suspected to the MS disease was observed, additional sequences such as: Sagittal FLAIR Fat Sat, Sagittal PDw-fat Sat, Sagittal PDw-water sat was also performed. This study was performed in about 52 lesions and the results in more than 19 lesions showed that, for the Subcortical and Infratentorial areas, PDWw sequence with fat suppression is the best choice, And in nearly 33 plaques located in Periventricular area, FLAIR Fat Sat was the most effective sequence than both PDw fat and water suppression pulse sequences. Although large plaques may visible in all images, but important problem in patients with suspected MS is screening the tiny MS plaques. This study showed that for revealing the MS plaques located in the Subcortical and Infratentorial areas, PDw-fat sat is the most effective sequence, and for MS plaques in the periventricular area, FLAIR fat Sat is the best choice.

  1. Scan time reduction in {sup 23}Na-Magnetic Resonance Imaging using the chemical shift imaging sequence. Evaluation of an iterative reconstruction method

    Energy Technology Data Exchange (ETDEWEB)

    Weingaertner, Sebastian; Konstandin, Simon; Schad, Lothar R. [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine; Wetterling, Friedrich [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine; Dublin Univ. (Ireland) Trinity Inst. of Neuroscience; Fatar, Marc [Heidelberg Univ., Mannheim (Germany). Dept. of Neurology; Neumaier-Probst, Eva [Heidelberg Univ., Mannheim (Germany). Dept. of Neuroradiology

    2015-07-01

    To evaluate potential scan time reduction in {sup 23}Na-Magnetic Resonance Imaging with the chemical shift imaging sequence (CSI) using undersampled data of high-quality datasets, reconstructed with an iterative constrained reconstruction, compared to reduced resolution or reduced signal-to-noise ratio. CSI {sup 23}Na-images were retrospectively undersampled and reconstructed with a constrained reconstruction scheme. The results were compared to conventional methods of scan time reduction. The constrained reconstruction scheme used a phase constraint and a finite object support, which was extracted from a spatially registered {sup 1}H-image acquired with a double-tuned coil. The methods were evaluated using numerical simulations, phantom images and in-vivo images of a healthy volunteer and a patient who suffered from cerebral ischemic stroke. The constrained reconstruction scheme showed improved image quality compared to a decreased number of averages, images with decreased resolution or circular undersampling with weighted averaging for any undersampling factor. Brain images of a stroke patient, which were reconstructed from three-fold undersampled k-space data, resulted in only minor differences from the original image (normalized root means square error < 12%) and an almost identical delineation of the stroke region (mismatch < 6%). The acquisition of undersampled {sup 23}Na-CSI images enables up to three-fold scan time reduction with improved image quality compared to conventional methods of scan time saving.

  2. SWI or T2*: which MRI sequence to use in the detection of cerebral microbleeds? The Karolinska Imaging Dementia Study.

    Science.gov (United States)

    Shams, S; Martola, J; Cavallin, L; Granberg, T; Shams, M; Aspelin, P; Wahlund, L O; Kristoffersen-Wiberg, M

    2015-06-01

    Cerebral microbleeds are thought to have potentially important clinical implications in dementia and stroke. However, the use of both T2* and SWI MR imaging sequences for microbleed detection has complicated the cross-comparison of study results. We aimed to determine the impact of microbleed sequences on microbleed detection and associated clinical parameters. Patients from our memory clinic (n = 246; 53% female; mean age, 62) prospectively underwent 3T MR imaging, with conventional thick-section T2*, thick-section SWI, and conventional thin-section SWI. Microbleeds were assessed separately on thick-section SWI, thin-section SWI, and T2* by 3 raters, with varying neuroradiologic experience. Clinical and radiologic parameters from the dementia investigation were analyzed in association with the number of microbleeds in negative binomial regression analyses. Prevalence and number of microbleeds were higher on thick-/thin-section SWI (20/21%) compared with T2*(17%). There was no difference in microbleed prevalence/number between thick- and thin-section SWI. Interrater agreement was excellent for all raters and sequences. Univariate comparisons of clinical parameters between patients with and without microbleeds yielded no difference across sequences. In the regression analysis, only minor differences in clinical associations with the number of microbleeds were noted across sequences. Due to the increased detection of microbleeds, we recommend SWI as the sequence of choice in microbleed detection. Microbleeds and their association with clinical parameters are robust to the effects of varying MR imaging sequences, suggesting that comparison of results across studies is possible, despite differing microbleed sequences. © 2015 by American Journal of Neuroradiology.

  3. Magnetic resonance imaging (MRI) of articular cartilage of the knee using ultrashort echo time (uTE) sequences with spiral acquisition

    International Nuclear Information System (INIS)

    Goto, Hajimu; Fujii, Masahiko; Iwama, Yuki; Aoyama, Nobukazu; Ohno, Yoshiharu; Sugimura, Kazuro

    2012-01-01

    The objective of this study was to evaluate the sensitivity of ultrashort echo time (uTE) sequence for visualisation of calcified deep layers of articular cartilage. MRI with a uTE sequence was performed on five healthy volunteers. Signals from the calcified deep layers of the articular knee cartilage were evaluated on uTE subtraction images and computed tomography images. The calcified deep layers of the articular cartilage changed from having a low to a high signal when imaged with a uTE sequence. The reported uTE sequence was effective in imaging the deep layers of the knee cartilage.

  4. Direct atomic fabrication and dopant positioning in Si using electron beams with active real-time image-based feedback

    Science.gov (United States)

    Jesse, Stephen; Hudak, Bethany M.; Zarkadoula, Eva; Song, Jiaming; Maksov, Artem; Fuentes-Cabrera, Miguel; Ganesh, Panchapakesan; Kravchenko, Ivan; Snijders, Panchapakesan C.; Lupini, Andrew R.; Borisevich, Albina Y.; Kalinin, Sergei V.

    2018-06-01

    Semiconductor fabrication is a mainstay of modern civilization, enabling the myriad applications and technologies that underpin everyday life. However, while sub-10 nanometer devices are already entering the mainstream, the end of the Moore’s law roadmap still lacks tools capable of bulk semiconductor fabrication on sub-nanometer and atomic levels, with probe-based manipulation being explored as the only known pathway. Here we demonstrate that the atomic-sized focused beam of a scanning transmission electron microscope can be used to manipulate semiconductors such as Si on the atomic level, inducing growth of crystalline Si from the amorphous phase, reentrant amorphization, milling, and dopant front motion. These phenomena are visualized in real-time with atomic resolution. We further implement active feedback control based on real-time image analytics to automatically control the e-beam motion, enabling shape control and providing a pathway for atom-by-atom correction of fabricated structures in the near future. These observations open a new epoch for atom-by-atom manufacturing in bulk, the long-held dream of nanotechnology.

  5. Direct atomic fabrication and dopant positioning in Si using electron beams with active real-time image-based feedback.

    Science.gov (United States)

    Jesse, Stephen; Hudak, Bethany M; Zarkadoula, Eva; Song, Jiaming; Maksov, Artem; Fuentes-Cabrera, Miguel; Ganesh, Panchapakesan; Kravchenko, Ivan; Snijders, Panchapakesan C; Lupini, Andrew R; Borisevich, Albina Y; Kalinin, Sergei V

    2018-06-22

    Semiconductor fabrication is a mainstay of modern civilization, enabling the myriad applications and technologies that underpin everyday life. However, while sub-10 nanometer devices are already entering the mainstream, the end of the Moore's law roadmap still lacks tools capable of bulk semiconductor fabrication on sub-nanometer and atomic levels, with probe-based manipulation being explored as the only known pathway. Here we demonstrate that the atomic-sized focused beam of a scanning transmission electron microscope can be used to manipulate semiconductors such as Si on the atomic level, inducing growth of crystalline Si from the amorphous phase, reentrant amorphization, milling, and dopant front motion. These phenomena are visualized in real-time with atomic resolution. We further implement active feedback control based on real-time image analytics to automatically control the e-beam motion, enabling shape control and providing a pathway for atom-by-atom correction of fabricated structures in the near future. These observations open a new epoch for atom-by-atom manufacturing in bulk, the long-held dream of nanotechnology.

  6. A compact 16-module camera using 64-pixel CsI(Tl)/Si p-i-n photodiode imaging modules

    Science.gov (United States)

    Choong, W.-S.; Gruber, G. J.; Moses, W. W.; Derenzo, S. E.; Holland, S. E.; Pedrali-Noy, M.; Krieger, B.; Mandelli, E.; Meddeler, G.; Wang, N. W.; Witt, E. K.

    2002-10-01

    We present a compact, configurable scintillation camera employing a maximum of 16 individual 64-pixel imaging modules resulting in a 1024-pixel camera covering an area of 9.6 cm/spl times/9.6 cm. The 64-pixel imaging module consists of optically isolated 3 mm/spl times/3 mm/spl times/5 mm CsI(Tl) crystals coupled to a custom array of Si p-i-n photodiodes read out by a custom integrated circuit (IC). Each imaging module plugs into a readout motherboard that controls the modules and interfaces with a data acquisition card inside a computer. For a given event, the motherboard employs a custom winner-take-all IC to identify the module with the largest analog output and to enable the output address bits of the corresponding module's readout IC. These address bits identify the "winner" pixel within the "winner" module. The peak of the largest analog signal is found and held using a peak detect circuit, after which it is acquired by an analog-to-digital converter on the data acquisition card. The camera is currently operated with four imaging modules in order to characterize its performance. At room temperature, the camera demonstrates an average energy resolution of 13.4% full-width at half-maximum (FWHM) for the 140-keV emissions of /sup 99m/Tc. The system spatial resolution is measured using a capillary tube with an inner diameter of 0.7 mm and located 10 cm from the face of the collimator. Images of the line source in air exhibit average system spatial resolutions of 8.7- and 11.2-mm FWHM when using an all-purpose and high-sensitivity parallel hexagonal holes collimator, respectively. These values do not change significantly when an acrylic scattering block is placed between the line source and the camera.

  7. An objective method to optimize the MR sequence set for plaque classification in carotid vessel wall images using automated image segmentation.

    Directory of Open Access Journals (Sweden)

    Ronald van 't Klooster

    Full Text Available A typical MR imaging protocol to study the status of atherosclerosis in the carotid artery consists of the application of multiple MR sequences. Since scanner time is limited, a balance has to be reached between the duration of the applied MR protocol and the quantity and quality of the resulting images which are needed to assess the disease. In this study an objective method to optimize the MR sequence set for classification of soft plaque in vessel wall images of the carotid artery using automated image segmentation was developed. The automated method employs statistical pattern recognition techniques and was developed based on an extensive set of MR contrast weightings and corresponding manual segmentations of the vessel wall and soft plaque components, which were validated by histological sections. Evaluation of the results from nine contrast weightings showed the tradeoff between scan duration and automated image segmentation performance. For our dataset the best segmentation performance was achieved by selecting five contrast weightings. Similar performance was achieved with a set of three contrast weightings, which resulted in a reduction of scan time by more than 60%. The presented approach can help others to optimize MR imaging protocols by investigating the tradeoff between scan duration and automated image segmentation performance possibly leading to shorter scanning times and better image interpretation. This approach can potentially also be applied to other research fields focusing on different diseases and anatomical regions.

  8. Impact of P and Sr on solidification sequence and morphology of hypoeutectic Al–Si alloys: Combined thermodynamic computation and phase-field simulation

    International Nuclear Information System (INIS)

    Eiken, Janin; Apel, Markus; Liang, Song-Mao; Schmid-Fetzer, Rainer

    2015-01-01

    Even small amounts of Phosphorus and Strontium strongly affect the microstructure of hypoeutectic Al–Si alloys. P is an unavoidable trace element in commercial Al-alloys which causes formation of AlP particles as potent nucleation sites for eutectic (Si). Sr, in contrast, is purposely added to modify the morphology of eutectic (Si) towards fine coral-like fibers. It is hypothesized that Sr does not only alter the growth kinetics of (Si), but additionally prevents detrimental (Si) nucleation due to neutralization of AlP particles by Al 2 Si 2 Sr formation. This presumes that both AlP and Al 2 Si 2 Sr precipitate prior to (Si). Using a newly assessed thermodynamic database for the Al–Si–Sr–P system, critical P and Sr thresholds for pre-silicon formation of AlP and Al 2 Si 2 Sr were evaluated and mapped under equilibrium and Scheil conditions. The competitive precipitation of AlP, Al 2 Si 2 Sr and (Si) and its impact on the evolution of the eutectic morphology was further studied by 3D phase-field simulations. Effective anisotropy functions for the (Si) interface mobility considered Sr-induced internal twinning. Depending on whether subcritical or supercritical P and Sr contents were selected, either a fine lamellar structure, a coarse flaky structure, or the targeted fine fibrous eutectic structure was reproduced

  9. MR imaging at 0.5 Tesla with FLAIR sequence in the diagnosis of acute subarachnoid hemorrhage

    International Nuclear Information System (INIS)

    Kopsa, W.; Leitner, H.; Tscholakoff, D.; Perneczky, G.

    1998-01-01

    Purpose: Evaluation of MR imaging in patients with acute subarachnoid hemorrhage (SAH) at 0.5 Tesla using the FLAIR (Fluid Attenuated Inversion Recovery) sequenze. Additionally, the value of MR angiographie (MRA) in the diagnosis of intracranial aneurysms was assessed. Materials and Methods: 19 patients with suspected acute SAH were included in this study. MR imaging was performed using an axial FLAIR sequence and axial T 1 , T 2 and PD weighted sequences. In 16 patients an additional MRA (3D-TOF) was performed. 10 patients without SAH were examined as a control group. At the end of the study the 29 MR examinations were randomised and the images were read by two experienced radiologists; subsequently a consensus interpretation was made. Results: In 16 patients an acute SAH was verified with the FLAIR sequence, in 13 cases the origin of hemorrhage was found during surgery. In the consensus interpretation of the MR images all cases were diagnosed properly. 12 of the 16 MRA studies were of diagnostic quality, but only 6 cases were interpreted correctly. Conclusion: The FLAIR sequence at 0.5 Tesla proved effective in the diagnosis of acute SAH. MRA at 0.5 Tesla failed in the detection of intracranial aneurysms. (orig.) [de

  10. The estimation of geometry and motion of a surface from image sequences by means of linearisation of a paramatric model

    NARCIS (Netherlands)

    Korsten, Maarten J.; Houkes, Z.

    1990-01-01

    A method is given to estimate the geometry and motion of a moving body surface from image sequences. To this aim a parametric model of the surface is used, in order to reformulate the problem to one of parameter estimation. After linearization of the model standard linear estimation methods can be

  11. MR imaging of articular cartilage in the knee. Evaluation of cadaver knee by 3D FLASH sequence with fat saturation

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Katsuhiko; Hachiya, Junichi; Matsumura, Joji [Kyorin Univ., Mitaka, Tokyo (Japan). School of Medicine

    1999-06-01

    MR imaging of the articular cartilage of the 24 cadever knees was performed using 3D FLASH sequence with fat saturation. Good correlation was noted between MR findings and either macroscopic or microscopic appearances of the hyaline cartilage. Low signal intensity area without significant thinning of the cartilage was considered to represent the degenerative changes due to relatively early process of osteoarthritis. (author)

  12. Imaging of cranial nerves with three-dimensional high resolution diffusion-weighted MR sequence based on SSFP technique

    International Nuclear Information System (INIS)

    Zhang Zhongwei; Chen Yingming; Meng Quanfei

    2008-01-01

    Objective: To depict the normal anatomy of cranial nerves in detail and define the exact relationships between cranial nerves and adjacent structures with three-dimensional high resolution diffusion-weighted MR sequence based on SSFP technique (3D DW-SSFP). Methods: 3D DW- SSFP sequence was performed and axial images were obtained in 12 healthy volunteers Post-processing techniques were used to generate images of cranial nerves, and the images acquired were compared with anatomical sections and diagrams of textbook. Results: In all subjects, 3D DW-SSFP sequence could produce homogeneous images and high contrast between the cranial nerves and other solid structures. The intracranial portions of all cranial nerves except olfactory nerve were identified; the extracranial portions of nerve Ⅱ-Ⅻ were identified in all subjects bilaterally. Conclusion: The 3D DW-SSFP sequence can characterize the normal MR appearance of cranial nerves and its branches and the ability to define the nerves may provide greater sensitivity and specificity in detecting abnormalities of craniofacial structure. (authors)

  13. Batch-processing of imaging or liquid-chromatography mass spectrometry datasets and De Novo sequencing of polyketide siderophores

    Czech Academy of Sciences Publication Activity Database

    Novák, Jiří; Sokolová, Lucie; Lemr, Karel; Pluháček, Tomáš; Palyzová, Andrea; Havlíček, Vladimír

    2017-01-01

    Roč. 1865, č. 7 (2017), s. 768-775 ISSN 1570-9639 R&D Projects: GA ČR(CZ) GA16-20229S; GA MŠk(CZ) LO1509 Institutional support: RVO:61388971 Keywords : Mass spectrometry imaging * De novo sequencing * Siderophores Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.773, year: 2016

  14. Nanostructures to modulate vascular inflammation: Multifunctional nanoparticles for quantifiable siRNA delivery and molecular imaging

    Science.gov (United States)

    Kaneda, Megan Marie

    Early steps in the progression of inflammatory diseases such as atherosclerosis involve the recruitment of leukocytes to the vascular endothelium through the expression or up-regulation of adhesion molecules. These adhesion molecules are critical mediators of leukocyte attachment and subsequent extravasation through transendothelial migration. One of these adhesion molecules, vascular cell adhesion molecule-1 (VCAM-1) is particularly attractive as a marker of early atherosclerotic activity due to its low expression level on normal endothelium and up-regulation prior to and during the development of early lesions. With this in mind, the purpose of this thesis was to develop nanostructures for the detection and down-regulation of adhesion molecules by the vascular endothelium. To detect early inflammation we designed a perfluorocarbon nanoparticle (PFC-NP) probe, which was used for in vivo targeting of VCAM-1. Nanoparticles were detected ex vivo by the magnetic resonance (MR) signature from the fluorine core of the particle. Nanoparticles accumulated in tissues characterized by early inflammatory processes. To down-regulate VCAM-1 expression by vascular endothelial cells, cationic PFC-NP were produced through the addition of the cationic lipid 1,2-Dioleoyl-3-Trimethylammonium-Propane. Cationic PFC-NP were able to deliver anti-VCAM-1 siRNA to endothelial cells through a non-standard lipid raft mediated endocytic pathway. VCAM-1 levels were significantly reduced in treated cells indicating that this delivery mechanism may be advantageous for delivery of cargo into the cytoplasm. Using the fluorine signature from the core of the cationic PFC-NP, we were able to quantify and localize this siRNA delivery agent both in vitro and in vivo. The ability to quantify the local concentrations of these particles could be of great benefit for estimating local drug concentrations and developing new pharmacokinetic and pharmacodynamic paradigms to describe this new class of

  15. Magnetic resonance visualization of conductive structures by sequence-triggered direct currents and spin-echo phase imaging

    Energy Technology Data Exchange (ETDEWEB)

    Eibofner, Frank; Wojtczyk, Hanne; Graf, Hansjörg, E-mail: hansjoerg.graf@med.uni-tuebingen.de, E-mail: drGraf@t-online.de [Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany); Clasen, Stephan [Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany)

    2014-06-15

    Purpose: Instrument visualization in interventional magnetic resonance imaging (MRI) is commonly performed via susceptibility artifacts. Unfortunately, this approach suffers from limited conspicuity in inhomogeneous tissue and disturbed spatial encoding. Also, susceptibility artifacts are controllable only by sequence parameters. This work presents the basics of a new visualization method overcoming such problems by applying sequence-triggered direct current (DC) pulses in spin-echo (SE) imaging. SE phase images allow for background free current path localization. Methods: Application of a sequence-triggered DC pulse in SE imaging, e.g., during a time period between radiofrequency excitation and refocusing, results in transient field inhomogeneities. Dependent on the additional z-magnetic field from the DC, a phase offset results despite the refocusing pulse. False spatial encoding is avoided by DC application during periods when read-out or slice-encoding gradients are inactive. A water phantom containing a brass conductor (water equivalent susceptibility) and a titanium needle (serving as susceptibility source) was used to demonstrate the feasibility. Artifact dependence on current strength and orientation was examined. Results: Without DC, the brass conductor was only visible due to its water displacement. The titanium needle showed typical susceptibility artifacts. Applying triggered DC pulses, the phase offset of spins near the conductor appeared. Because SE phase images are homogenous also in regions of persistent field inhomogeneities, the position of the conductor could be determined with high reliability. Artifact characteristic could be easily controlled by amperage leaving sequence parameters unchanged. For an angle of 30° between current and static field visualization was still possible. Conclusions: SE phase images display the position of a conductor carrying pulsed DC free from artifacts caused by persistent field inhomogeneities. Magnitude and phase

  16. Design and evaluation of a SiPM-based large-area detector module for positron emission imaging

    Science.gov (United States)

    Alva-Sánchez, H.; Murrieta-Rodríguez, T.; Calva-Coraza, E.; Martínez-Dávalos, A.; Rodríguez-Villafuerte, M.

    2018-03-01

    The design and evaluation of a large-area detector module for positron emission imaging applications, is presented. The module features a SensL ArrayC-60035-64P-PCB solid state detector (8×8 array of tileable silicon photomultipliers by SensL, 7.2 mm pitch) covering a total area of 57.4×57.4 mm2. The detector module was formed using a pixelated array of 40×40 lutetium-yttrium oxyorthosilicate (LYSO) scintillator crystal elements with 1.43 mm pitch. A 7 mm thick coupling light guide was used to allow light sharing between adjacent SiPM. A 16-channel symmetric charge division (SCD) readout board was designed to multiplex the number of signals from 64 to 16 (8 columns and 8 rows) and a center-of-gravity algorithm to identify the position. Data acquisition and digitization was accomplished using a custom-made system based on FPGAs boards. Crystal maps were obtained using 18F-positron sources and Voronoi diagrams were used to correct for geometric distortions and to generate a non-uniformity correction matrix. All measurements were taken at a controlled room temperature of 22oC. The crystal maps showed minor distortion, 90% of the 1600 total crystal elements could be identified, a mean peak-to-valley ratio of 4.3 was obtained and a 10.8% mean energy resolution for 511 keV annihilation photons was determined. The performance of the detector using our own readout board was compared to that using two different commercially readout boards using the same detector module arrangement. We show that these large-area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, excellent energy resolution and detector uniformity and thus, can be used for positron emission imaging applications.

  17. A FAST SEGMENTATION ALGORITHM FOR C-V MODEL BASED ON EXPONENTIAL IMAGE SEQUENCE GENERATION

    Directory of Open Access Journals (Sweden)

    J. Hu

    2017-09-01

    Full Text Available For the island coastline segmentation, a fast segmentation algorithm for C-V model method based on exponential image sequence generation is proposed in this paper. The exponential multi-scale C-V model with level set inheritance and boundary inheritance is developed. The main research contributions are as follows: 1 the problems of the "holes" and "gaps" are solved when extraction coastline through the small scale shrinkage, low-pass filtering and area sorting of region. 2 the initial value of SDF (Signal Distance Function and the level set are given by Otsu segmentation based on the difference of reflection SAR on land and sea, which are finely close to the coastline. 3 the computational complexity of continuous transition are successfully reduced between the different scales by the SDF and of level set inheritance. Experiment results show that the method accelerates the acquisition of initial level set formation, shortens the time of the extraction of coastline, at the same time, removes the non-coastline body part and improves the identification precision of the main body coastline, which automates the process of coastline segmentation.

  18. a Fast Segmentation Algorithm for C-V Model Based on Exponential Image Sequence Generation

    Science.gov (United States)

    Hu, J.; Lu, L.; Xu, J.; Zhang, J.

    2017-09-01

    For the island coastline segmentation, a fast segmentation algorithm for C-V model method based on exponential image sequence generation is proposed in this paper. The exponential multi-scale C-V model with level set inheritance and boundary inheritance is developed. The main research contributions are as follows: 1) the problems of the "holes" and "gaps" are solved when extraction coastline through the small scale shrinkage, low-pass filtering and area sorting of region. 2) the initial value of SDF (Signal Distance Function) and the level set are given by Otsu segmentation based on the difference of reflection SAR on land and sea, which are finely close to the coastline. 3) the computational complexity of continuous transition are successfully reduced between the different scales by the SDF and of level set inheritance. Experiment results show that the method accelerates the acquisition of initial level set formation, shortens the time of the extraction of coastline, at the same time, removes the non-coastline body part and improves the identification precision of the main body coastline, which automates the process of coastline segmentation.

  19. INTEGRATED GEOREFERENCING OF STEREO IMAGE SEQUENCES CAPTURED WITH A STEREOVISION MOBILE MAPPING SYSTEM – APPROACHES AND PRACTICAL RESULTS

    Directory of Open Access Journals (Sweden)

    H. Eugster

    2012-07-01

    Full Text Available Stereovision based mobile mapping systems enable the efficient capturing of directly georeferenced stereo pairs. With today's camera and onboard storage technologies imagery can be captured at high data rates resulting in dense stereo sequences. These georeferenced stereo sequences provide a highly detailed and accurate digital representation of the roadside environment which builds the foundation for a wide range of 3d mapping applications and image-based geo web-services. Georeferenced stereo images are ideally suited for the 3d mapping of street furniture and visible infrastructure objects, pavement inspection, asset management tasks or image based change detection. As in most mobile mapping systems, the georeferencing of the mapping sensors and observations – in our case of the imaging sensors – normally relies on direct georeferencing based on INS/GNSS navigation sensors. However, in urban canyons the achievable direct georeferencing accuracy of the dynamically captured stereo image sequences is often insufficient or at least degraded. Furthermore, many of the mentioned application scenarios require homogeneous georeferencing accuracy within a local reference frame over the entire mapping perimeter. To achieve these demands georeferencing approaches are presented and cost efficient workflows are discussed which allows validating and updating the INS/GNSS based trajectory with independently estimated positions in cases of prolonged GNSS signal outages in order to increase the georeferencing accuracy up to the project requirements.

  20. Preliminary evaluation of a prototype stereoscopic a-Si:H-based X-ray imaging system for full-field digital mammography

    International Nuclear Information System (INIS)

    Darambara, D.G.; Speller, R.D.; Horrocks, J.A.; Godber, S.; Wilson, R.; Hanby, A.

    2001-01-01

    In a pre-clinical study, we have been investigating the potential of a-Si:H active matrix, flat panel imagers for X-ray full-field digital mammography through the development of an advanced 3D X-ray imaging system and have measured a number of their important imaging characteristics. To enhance the information embodied into the digital images produced by the a-Si array, stereoscopic images, created by viewing the object under examination from two angles and recombining the images, were obtained. This method provided us with a full 3D X-ray image of the test object as well as left and right perspective 2D images all at the same time. Within this scope, images of fresh, small human breast tissue specimens--normal and diseased--were obtained at ±2 deg., processed and stereoscopically displayed for a pre-clinical evaluation by radiologists. It was demonstrated that the stereoscopic presentation of the images provides important additional information and has potential benefits over the more traditional 2D data

  1. SiRNAs in vivo imaging: methodology of fluorine-18 radiolabelling and application for the optimization of the siRNAs biodistribution and pharmaceutical properties

    International Nuclear Information System (INIS)

    Viel, Th.

    2008-01-01

    As RNA interference is a natural process which enables eukaryote cells to regulate the gene expressions, to control transposons, and to struggle against some viruses, two imagery techniques have been used in this research, i.e. optical imagery and Positron Emission Tomography (PET) imagery, to study the various modifications of the small interferential RNAs (siRNA). Different chemically modified siRNAs have been prepared and their in vitro activity, their in vivo metabolism (by HPLC analysis), their bio-distribution and their pharmacokinetic properties (by PET imagery) after marking them with fluorine-18. Their in vivo activity has been assessed by optical imagery

  2. Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

    Science.gov (United States)

    Cho, Hyo-Min; Barber, William C.; Ding, Huanjun; Iwanczyk, Jan S.; Molloi, Sabee

    2014-01-01

    Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A109Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm2) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy resolution

  3. A compact, discrete CsI(Tl) scintillator/Si photodiode gamma camera for breast cancer imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Gregory J. [Univ. of California, Berkeley, CA (United States)

    2000-01-01

    Recent clinical evaluations of scintimammography (radionuclide breast imaging) are promising and suggest that this modality may prove a valuable complement to X-ray mammography and traditional breast cancer detection and diagnosis techniques. Scintimammography, however, typically has difficulty revealing tumors that are less than 1 cm in diameter, are located in the medial part of the breast, or are located in the axillary nodes. These shortcomings may in part be due to the use of large, conventional Anger cameras not optimized for breast imaging. In this thesis I present compact single photon camera technology designed specifically for scintimammography which strives to alleviate some of these limitations by allowing better and closer access to sites of possible breast tumors. Specific applications are outlined. The design is modular, thus a camera of the desired size and geometry can be constructed from an array (or arrays) of individual modules and a parallel hole lead collimator for directional information. Each module consists of: (1) an array of 64 discrete, optically-isolated CsI(Tl) scintillator crystals 3 x 3 x 5 mm3 in size, (2) an array of 64 low-noise Si PIN photodiodes matched 1-to-1 to the scintillator crystals, (3) an application-specific integrated circuit (ASIC) that amplifies the 64 photodiode signals and selects the signal with the largest amplitude, and (4) connectors and hardware for interfacing the module with a motherboard, thereby allowing straightforward computer control of all individual modules within a camera.

  4. A compact, discrete CsI(Tl) scintillator/Si photodiode gamma camera for breast cancer imaging

    International Nuclear Information System (INIS)

    Gruber, Gregory J.

    2000-01-01

    Recent clinical evaluations of scintimammography (radionuclide breast imaging) are promising and suggest that this modality may prove a valuable complement to X-ray mammography and traditional breast cancer detection and diagnosis techniques. Scintimammography, however, typically has difficulty revealing tumors that are less than 1 cm in diameter, are located in the medial part of the breast, or are located in the axillary nodes. These shortcomings may in part be due to the use of large, conventional Anger cameras not optimized for breast imaging. In this thesis I present compact single photon camera technology designed specifically for scintimammography which strives to alleviate some of these limitations by allowing better and closer access to sites of possible breast tumors. Specific applications are outlined. The design is modular, thus a camera of the desired size and geometry can be constructed from an array (or arrays) of individual modules and a parallel hole lead collimator for directional information. Each module consists of: (1) an array of 64 discrete, optically-isolated CsI(Tl) scintillator crystals 3 x 3 x 5 mm 3 in size, (2) an array of 64 low-noise Si PIN photodiodes matched 1-to-1 to the scintillator crystals, (3) an application-specific integrated circuit (ASIC) that amplifies the 64 photodiode signals and selects the signal with the largest amplitude, and (4) connectors and hardware for interfacing the module with a motherboard, thereby allowing straightforward computer control of all individual modules within a camera

  5. Comparison of modern 3D and 2D MR imaging sequences of the wrist at 3 Tesla

    International Nuclear Information System (INIS)

    Rehnitz, C.; Klaan, B.; Amarteifio, E.; Kauczor, H.U.; Weber, M.A.; Stillfried, F. von; Burkholder, I.

    2016-01-01

    To compare the image quality of modern 3 D and 2 D sequences for dedicated wrist imaging at 3 Tesla (T) MRI. At 3 T MRI, 18 patients (mean age: 36.2 years) with wrist pain and 16 healthy volunteers (mean age: 26.4 years) were examined using 2 D proton density-weighted fat-saturated (PDfs), isotropic 3 D TrueFISP, 3 D MEDIC, and 3 D PDfs SPACE sequences. Image quality was rated on a five-point scale (0 - 4) including overall image quality (OIQ), visibility of important structures (cartilage, ligaments, TFCC) and degree of artifacts. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) of cartilage/bone/muscle/fluid as well as the mean overall SNR/CNR were calculated using region-of-interest analysis. ANOVA, paired t-, and Wilcoxon-signed-rank tests were applied. The image quality of all tested sequences was superior to 3 D PDfs SPACE (p < 0.01). 3 D TrueFISP had the highest combined cartilage score (mean: 3.4) and performed better in cartilage comparisons against 3 D PDfs SPACE in both groups and 2 D PDfs in volunteers (p < 0.05). 3 D MEDIC performed better in 7 of 8 comparisons (p < 0.05) regarding ligaments and TFCC. 2 D PDfs provided constantly high scores. The mean overall SNR/CNR for 2 D PDfs, 3 D PDfs SPACE, 3 D TrueFISP, and 3 D MEDIC were 68/65, 32/27, 45/47, and 57/45, respectively. 2 D PDfs performed best in most SNR/CNR comparisons (p < 0.05) and 3 D MEDIC performed best within the 3 D sequences (p < 0.05). Except 3 D PDfs SPACE, all tested 3 D and 2 D sequences provided high image quality. 3 D TrueFISP was best for cartilage imaging, 3 D MEDIC for ligaments and TFCC and 2 D PDfs for general wrist imaging.

  6. Basic evaluation of the new pulse sequence for simultaneous acquisition of T1- and T2-weighted images

    International Nuclear Information System (INIS)

    Kurose, Atsunari; Takahashi, Tohru; Ohishi, Tae; Ishikawa, Akihiro

    2006-01-01

    A novel pulse sequence that enables simultaneous acquisition of T1-weighted (T1W) and T2-weighted (T2W) images is presented. In this new technique, the inversion recovery (IR) pulse of conventional fast inversion recovery (Fast IR) is replaced with a pulse train that consists of a fast spin echo (FSE) and 180(y)+90(x) for driven inversion (DI). By using a shorter T1 and independent k-space ordering, the first part of the sequence provides T2W images and the second part provides T1W images, thereby enabling simultaneous acquisition in a single scan time comparable to that of Fast IR. Signal simulation also was conducted, and this was compared with conventional scanning techniques using normal volunteers. In the human studies, both T1W and T2W images showed the same image quality as conventional images, suggesting the potential for this technique to replace the combination of Fast IR and T2W FSE for scan-time reduction. (author)

  7. Protocol optimization of sacroiliac joint MR Imaging at 3 Tesla: Impact of coil design and motion resistant sequences on image quality.

    Science.gov (United States)

    Gondim Teixeira, P A; Bravetti, M; Hossu, G; Lecocq, S; Petit, D; Loeuille, D; Blum, A

    2017-12-01

    To evaluate the impact of coil design and motion-resistant sequences on the quality of sacroiliac magnetic resonance imaging (MRI) examination in patients with spondyloarthropathy. One hundred and twenty-one patients with suspected sacroiliitis and referred for MRI of the sacroiliac joints were retrospectively evaluated with MRI at 3-Tesla. There were 78 women and 43 men with a mean age of 36.7±11.5 (SD) years (range: 15.8-78.4 years). Conventional and motion-resistant fat-saturated fast-spin echo T2-weighted sequences were performed with two different coils. Image quality was subjectively evaluated by two independent readers (R1 and R2) using a four-point scale. Confidence in the identification of bone marrow edema pattern (BMEP) was also evaluated subjectively using a three-point scale. Phased array body coil yielded improved image quality compared to surface coil (14.1 to 30.4% for R1 and 14.6 to 25.7% for R2; Pcoil with motion-resistant T2-weighted sequence (kappa 0.990). The smallest number of indeterminate BMEP zones was seen on MRI set acquired with the phased-array body coil and motion-resistant T2-weighted sequence. Phased array body coil and motion-resistant T2-weighted sequences perform better than surface coil and conventional T2-weighted sequences for the evaluation of sacroiliac joints, increasing confidence in the identification of BMEP. Copyright © 2017 Editions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  8. Tumor responsive targeted multifunctional nanosystems for cancer imaging, chemo- and siRNA therapy

    Science.gov (United States)

    Savla, Ronak

    Cancer is one of the most insidious diseases. Compromising of over 100 different types and sharing the unifying factors of uncontrolled growth and metastasis, unmet clinical needs in terms of cancer diagnosis and treatment continue to exist. It is widely accepted that most forms of cancer are treatable or even curable if detected before widespread metastasis occurs. Nearly a quarter of deaths in the United States is the result of cancer and it only trails heart disease in terms of annual mortality. Surgery, chemotherapy, and radiation therapy are the primary treatment modalities for cancer. Research in these procedures has resulted in substantial benefits for cancer patients, but there is still room for an improvement. However, a time has been reached at which it appears that the benefits from these modalities have been reached the maximum. Therefore, it is vital to develop new strategies for the diagnosis and treatment of cancer. The field of nanotechnology is concerned with structures in the nanometer size range and holds the potential to drastically impact and improve the lives of patients suffering from cancer. Not only can nanotechnology improve current methods of diagnosis and treatment, it has a possibility of introducing newer and better modalities. The overall purpose of this work is to develop novel nanotechnology-based methodologies for the diagnosis and treatment of various forms of cancers. The first aim of the project is the development of a multifunctional targeted nanosystem for the delivery of siRNA to overcome drug resistance. The second aspect is the synthesis of a quantum dot-based delivery system that releases drug in response to pH changes. The third aim is the development of a targeted, tumor environment responsive magnetic resonance nanoparticle contrast agent coupled with a nanoparticle-based treatment.

  9. Method for automatic localization of MR-visible markers using morphological image processing and conventional pulse sequences: feasibility for image-guided procedures.

    Science.gov (United States)

    Busse, Harald; Trampel, Robert; Gründer, Wilfried; Moche, Michael; Kahn, Thomas

    2007-10-01

    To evaluate the feasibility and accuracy of an automated method to determine the 3D position of MR-visible markers. Inductively coupled RF coils were imaged in a whole-body 1.5T scanner using the body coil and two conventional gradient echo sequences (FLASH and TrueFISP) and large imaging volumes up to (300 mm(3)). To minimize background signals, a flip angle of approximately 1 degrees was used. Morphological 2D image processing in orthogonal scan planes was used to determine the 3D positions of a configuration of three fiducial markers (FMC). The accuracies of the marker positions and of the orientation of the plane defined by the FMC were evaluated at various distances r(M) from the isocenter. Fiducial marker detection with conventional equipment (pulse sequences, imaging coils) was very reliable and highly reproducible over a wide range of experimental conditions. For r(M) image processing is feasible, simple, and very accurate. In combination with safe wireless markers, the method is found to be useful for image-guided procedures. (c) 2007 Wiley-Liss, Inc.

  10. Evaluation of pneumonia in children: comparison of MRI with fast imaging sequences at 1.5T with chest radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Yikilmaz, Ali; Koc, Ali; Coskun, Abdulhakim (Dept. of Radiology, Erciyes Medical School, Kayseri (Turkey)); Ozturk, Mustafa K (Dept. of Pediatric Infectious Diseases, Erciyes Medical School, Kayseri (Turkey)); Mulkern, Robert V; Lee, Edward Y (Dept. of Radiology and Dept. of Medicine, Pulmonary Div., Children' s Hospital Boston and Harvard Medical School, Boston (United States)), email: Edward.lee@childrens.harvard.edu

    2011-10-15

    Background Although there has been a study aimed at magnetic resonance imaging (MRI) evaluation of pneumonia in children at a low magnetic field (0.2T), there is no study which assessed the efficacy of MRI, particularly with fast imaging sequences at 1.5T, for evaluating pneumonia in children. Purpose To investigate the efficacy of chest MRI with fast imaging sequences at 1.5T for evaluating pneumonia in children by comparing MRI findings with those of chest radiographs. Material and Methods This was an Institutional Review Board-approved, HIPPA-compliant prospective study of 40 consecutive pediatric patients (24 boys, 16 girls; mean age 7.3 years +- 6.6 years) with pneumonia, who underwent PA and lateral chest radiographs followed by MRI within 24 h. All MRI studies were obtained in axial and coronal planes with two different fast imaging sequences: T1-weighted FFE (Fast Field Echo) (TR/TE: 83/4.6) and T2-weighted B-FFE M2D (Balanced Fast Field Echo Multiple 2D Dimensional) (TR/TE: 3.2/1.6). Two experienced pediatric radiologists reviewed each chest radiograph and MRI for the presence of consolidation, necrosis/abscess, bronchiectasis, and pleural effusion. Chest radiograph and MRI findings were compared with Kappa statistics. Results All consolidation, lung necrosis/abscess, bronchiectasis, and pleural effusion detected with chest radiographs were also detected with MRI. There was statistically substantial agreement between chest radiographs and MRI in detecting consolidation (k = 0.78) and bronchiectasis (k = 0.72) in children with pneumonia. The agreement between chest radiographs and MRI was moderate for detecting necrosis/abscess (k = 0.49) and fair for detecting pleural effusion (k = 0.30). Conclusion MRI with fast imaging sequences is comparable to chest radiographs for evaluating underlying pulmonary consolidation, bronchiectasis, necrosis/abscess, and pleural effusion often associated with pneumonia in children

  11. Interfacial micropore defect formation in PEDOT:PSS-Si hybrid solar cells probed by TOF-SIMS 3D chemical imaging.

    Science.gov (United States)

    Thomas, Joseph P; Zhao, Liyan; Abd-Ellah, Marwa; Heinig, Nina F; Leung, K T

    2013-07-16

    Conducting p-type polymer layers on n-type Si have been widely studied for the fabrication of cost-effective hybrid solar cells. In this work, time-of-flight secondary ion mass spectrometry (TOF-SIMS) is used to provide three-dimensional chemical imaging of the interface between poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS) and SiOx/Si in a hybrid solar cell. To minimize structural damage to the polymer layer, an Ar cluster sputtering source is used for depth profiling. The present result shows the formation of micropore defects in the interface region of the PEDOT:PSS layer on the SiOx/Si substrate. This interfacial micropore defect formation becomes more prominent with increasing thickness of the native oxide layer, which is a key device parameter that greatly affects the hybrid solar cell performance. Three-dimensional chemical imaging coupled with Ar cluster ion sputtering has therefore been demonstrated as an emerging technique for probing the interface of this and other polymer-inorganic systems.

  12. STED Imaging of Golgi Dynamics with Cer-SiR: A Two-Component, Photostable, High-Density Lipid Probe for Live Cells.

    Science.gov (United States)

    Erdmann, Roman S; Toomre, Derek; Schepartz, Alanna

    2017-01-01

    Long time-lapse super-resolution imaging in live cells requires a labeling strategy that combines a bright, photostable fluorophore with a high-density localization probe. Lipids are ideal high-density localization probes, as they are >100 times more abundant than most membrane-bound proteins and simultaneously demark the boundaries of cellular organelles. Here, we describe Cer-SiR, a two-component, high-density lipid probe that is exceptionally photostable. Cer-SiR is generated in cells via a bioorthogonal reaction of two components: a ceramide lipid tagged with trans-cyclooctene (Cer-TCO) and a reactive, photostable Si-rhodamine dye (SiR-Tz). These components assemble within the Golgi apparatus of live cells to form Cer-SiR. Cer-SiR is benign to cellular function, localizes within the Golgi at a high density, and is sufficiently photostable to enable visualization of Golgi structure and dynamics by 3D confocal or long time-lapse STED microscopy.

  13. Comparative Analysis of Signal Intensity and Apparent Diffusion Coefficient at Varying b-values in the Brain : Diffusion Weighted-Echo Planar Image (T2 and FLAIR) Sequence

    International Nuclear Information System (INIS)

    Oh, Jong Kap; Im, Jung Yeol

    2009-01-01

    Diffusion-weighted imaging (DWI) has been demonstrated to be a practical method for the diagnosis of various brain diseases such as acute infarction, brain tumor, and white matter disease. In this study, we used two techniques to examine the average signal intensity (SI) and apparent diffusion coefficient (ADC) of the brains of patients who ranged in age from 10 to 60 years. Our results indicated that the average SI was the highest in amygdala (as derived from DWI), whereas that in the cerebrospinal fluid was the lowest. The average ADC was the highest in the cerebrospinal fluid, whereas the lowest measurement was derived from the pons. The average SI and ADC were higher in T 2 -DW-EPI than in FLAIR-DW-EPI. The higher the b-value, the smaller the average difference in both imaging techniques; the lower the b-value, the greater the average difference. Also, comparative analysis of the brains of patients who had experienced cerebral infarction showed no distinct lesion in the general MR image over time. However, there was a high SI in apparent weighted images. Analysis of other brain diseases (e.g., bleeding, acute, subacute, chronic infarction) indicated SI variance in accordance with characteristics of the two techniques. The higher the SI, the lower the ADC. Taken together, the value of SI and ADC in accordance with frequently occurring areas and various brain disease varies based on the b-value and imaging technique. Because they provide additional useful information in the diagnosis and treatment of patients with various brain diseases through signal recognition, the proper imaging technique and b-value are important for the detection and interpretation of subacute stroke and other brain diseases.

  14. Variability in prostate and seminal vesicle delineations defined on magnetic resonance images, a multi-observer, -center and -sequence study

    DEFF Research Database (Denmark)

    Nyholm, Tufve; Jonsson, Joakim; Söderström, Karin

    2013-01-01

    and approximately equal for the prostate and seminal vesicles. Large differences in variability were observed for individual patients, and also for individual imaging sequences used at the different centers. There was however no indication of decreased variability with higher field strength. CONCLUSION: The overall......BACKGROUND: The use of magnetic resonance (MR) imaging as a part of preparation for radiotherapy is increasing. For delineation of the prostate several publications have shown decreased delineation variability using MR compared to computed tomography (CT). The purpose of the present work....... Two physicians from each center delineated the prostate and the seminal vesicles on each of the 25 image sets. The variability between the delineations was analyzed with respect to overall, intra- and inter-physician variability, and dependence between variability and origin of the MR images, i...

  15. Infrared upconversion hyperspectral imaging

    DEFF Research Database (Denmark)

    Kehlet, Louis Martinus; Tidemand-Lichtenberg, Peter; Dam, Jeppe Seidelin

    2015-01-01

    In this Letter, hyperspectral imaging in the mid-IR spectral region is demonstrated based on nonlinear frequency upconversion and subsequent imaging using a standard Si-based CCD camera. A series of upconverted images are acquired with different phase match conditions for the nonlinear frequency...... conversion process. From this, a sequence of monochromatic images in the 3.2-3.4 mu m range is generated. The imaged object consists of a standard United States Air Force resolution target combined with a polystyrene film, resulting in the presence of both spatial and spectral information in the infrared...... image. (C) 2015 Optical Society of America...

  16. Pulseq-Graphical Programming Interface: Open source visual environment for prototyping pulse sequences and integrated magnetic resonance imaging algorithm development.

    Science.gov (United States)

    Ravi, Keerthi Sravan; Potdar, Sneha; Poojar, Pavan; Reddy, Ashok Kumar; Kroboth, Stefan; Nielsen, Jon-Fredrik; Zaitsev, Maxim; Venkatesan, Ramesh; Geethanath, Sairam

    2018-03-11

    To provide a single open-source platform for comprehensive MR algorithm development inclusive of simulations, pulse sequence design and deployment, reconstruction, and image analysis. We integrated the "Pulseq" platform for vendor-independent pulse programming with Graphical Programming Interface (GPI), a scientific development environment based on Python. Our integrated platform, Pulseq-GPI, permits sequences to be defined visually and exported to the Pulseq file format for execution on an MR scanner. For comparison, Pulseq files using either MATLAB only ("MATLAB-Pulseq") or Python only ("Python-Pulseq") were generated. We demonstrated three fundamental sequences on a 1.5 T scanner. Execution times of the three variants of implementation were compared on two operating systems. In vitro phantom images indicate equivalence with the vendor supplied implementations and MATLAB-Pulseq. The examples demonstrated in this work illustrate the unifying capability of Pulseq-GPI. The execution times of all the three implementations were fast (a few seconds). The software is capable of user-interface based development and/or command line programming. The tool demonstrated here, Pulseq-GPI, integrates the open-source simulation, reconstruction and analysis capabilities of GPI Lab with the pulse sequence design and deployment features of Pulseq. Current and future work includes providing an ISMRMRD interface and incorporating Specific Absorption Ratio and Peripheral Nerve Stimulation computations. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Investigation of tilted dose kernels for portal dose prediction in a-Si electronic portal imagers

    International Nuclear Information System (INIS)

    Chytyk, K.; McCurdy, B. M. C.

    2006-01-01

    The effect of beam divergence on dose calculation via Monte Carlo generated dose kernels was investigated in an amorphous silicon electronic portal imaging device (EPID). The flat-panel detector was simulated in EGSnrc with an additional 3.0 cm water buildup. The model included details of the detector's imaging cassette and the front cover upstream of it. To approximate the effect of the EPID's rear housing, a 2.1 cm air gap and 1.0 cm water slab were introduced into the simulation as equivalent backscatter material. Dose kernels were generated with an incident pencil beam of monoenergetic photons of energy 0.1, 2, 6, and 18 MeV. The orientation of the incident pencil beam was varied from 0 deg. to 14 deg. in 2 deg. increments. Dose was scored in the phosphor layer of the detector in both cylindrical (at 0 deg. ) and Cartesian (at 0 deg. -14 deg.) geometries. To reduce statistical fluctuations in the Cartesian geometry simulations at large radial distances from the incident pencil beam, the voxels were first averaged bilaterally about the pencil beam and then combined into concentric square rings of voxels. Profiles of the EPID dose kernels displayed increasing asymmetry with increasing angle and energy. A comparison of the superposition (tilted kernels) and convolution (parallel kernels) dose calculation methods via the χ-comparison test (a derivative of the γ-evaluation) in worst-case-scenario geometries demonstrated an agreement between the two methods within 0.0784 cm (one pixel width) distance-to-agreement and up to a 1.8% dose difference. More clinically typical field sizes and source-to-detector distances were also tested, yielding at most a 1.0% dose difference and the same distance-to-agreement. Therefore, the assumption of parallel dose kernels has less than a 1.8% dosimetric effect in extreme cases and less than a 1.0% dosimetric effect in most clinically relevant situations and should be suitable for most clinical dosimetric applications. The

  18. Thickness of patellofemoral articular cartilage as measured on MR imaging: sequence comparison of accuracy, reproducibility, and interobserver variation

    Energy Technology Data Exchange (ETDEWEB)

    Van Leersum, M.D. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States); Schweitzer, M.E. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States); Gannon, F. [Dept. of Pathology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States); Vinitski, S. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States); Finkel, G. [Dept. of Pathology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States); Mitchell, D.G. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States)

    1995-08-01

    This study was undertaken to assess the accuracy, precision, and reliability of magnetic resonance (MR) measurements of articular cartilage. Fifteen cadaveric patellas were imaged in the axial plane at 1.5 T. Gradient echo and fat-suppressed FSE, T2-weighted, proton density, and T1-weighted sequences were performed. We measured each 5-mm section separately at three standardized positions, giving a total of 900 measurements. These findings were correlated with independently performed measurements of the corresponding anatomic sections. A hundred random measurements were also evaluated for reproducibility and interobserver variation. Although all sequences were highly accurate, the T1-weighted images were the most accurate, with a mean difference of 0.25 mm and a correlation coefficient of 0.85. All sequences were also highly reproducible with little inter-observer variation. In an attempt to improve the accuracy of the MR measurements further, we retrospectively evaluated all measurements with discrepancies greater than 1 mm from the specimen. All these differences were attributable to focal defects causing exaggeration of the thickness on MR imaging. (orig.)

  19. Thickness of patellofemoral articular cartilage as measured on MR imaging: sequence comparison of accuracy, reproducibility, and interobserver variation

    International Nuclear Information System (INIS)

    Van Leersum, M.D.; Schweitzer, M.E.; Gannon, F.; Vinitski, S.; Finkel, G.; Mitchell, D.G.

    1995-01-01

    This study was undertaken to assess the accuracy, precision, and reliability of magnetic resonance (MR) measurements of articular cartilage. Fifteen cadaveric patellas were imaged in the axial plane at 1.5 T. Gradient echo and fat-suppressed FSE, T2-weighted, proton density, and T1-weighted sequences were performed. We measured each 5-mm section separately at three standardized positions, giving a total of 900 measurements. These findings were correlated with independently performed measurements of the corresponding anatomic sections. A hundred random measurements were also evaluated for reproducibility and interobserver variation. Although all sequences were highly accurate, the T1-weighted images were the most accurate, with a mean difference of 0.25 mm and a correlation coefficient of 0.85. All sequences were also highly reproducible with little inter-observer variation. In an attempt to improve the accuracy of the MR measurements further, we retrospectively evaluated all measurements with discrepancies greater than 1 mm from the specimen. All these differences were attributable to focal defects causing exaggeration of the thickness on MR imaging. (orig.)

  20. Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo sequence: improvement of the image quality of oxygen-enhanced MRI

    International Nuclear Information System (INIS)

    Ohno, Yoshiharu; Hatabu, Hiroto; Higashino, Takanori; Kawamitsu, Hideaki; Watanabe, Hirokazu; Takenaka, Daisuke; Cauteren, Marc van; Sugimura, Kazuro

    2004-01-01

    Purpose: The purpose of the study presented here was to determine the improvement in image quality of oxygen-enhanced magnetic resonance (MR) subtraction imaging obtained with a centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence compared with that obtained with a conventional sequentially reordered inversion recovery single-shot HASTE (s-IR-HASTE) sequence for pulmonary imaging. Materials and methods: Oxygen-enhanced MR imaging using a 1.5 T whole body scanner was performed on 12 healthy, non-smoking volunteers. Oxygen-enhanced MR images were obtained with the coronal two-dimensional (2D) c-IR-HASTE sequence and 2D s-IR-HASTE sequence combined with respiratory triggering. For a 256x256 matrix, 132 phase-encoding steps were acquired including four steps for phase correction. Inter-echo spacing for each sequence was 4.0 ms. The effective echo time (TE) for c-IR-HASTE was 4.0 ms, and 16 ms for s-IR-HASTE. The inversion time (TI) was 900 ms. To determine the improvement in oxygen-enhanced MR subtraction imaging by c-IR-HASTE, CNRs of subtraction image, overall image quality, and image degradation of the c-IR-HASTE and s-IR-HASTE techniques were statistically compared. Results: CNR, overall image quality, and image degradation of c-IR-HASTE images showed significant improvement compared to those s-IR-HASTE images (P<0.05). Conclusion: Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence enhanced the signal from the lung and improved the image quality of oxygen-enhanced MR subtraction imaging

  1. Automated Leaf Tracking using Multi-view Image Sequences of Maize Plants for Leaf-growth Monitoring

    Science.gov (United States)

    Das Choudhury, S.; Awada, T.; Samal, A.; Stoerger, V.; Bashyam, S.

    2017-12-01

    Extraction of phenotypes with botanical importance by analyzing plant image sequences has the desirable advantages of non-destructive temporal phenotypic measurements of a large number of plants with little or no manual intervention in a relatively short period of time. The health of a plant is best interpreted by the emergence timing and temporal growth of individual leaves. For automated leaf growth monitoring, it is essential to track each leaf throughout the life cycle of the plant. Plants are constantly changing organisms with increasing complexity in architecture due to variations in self-occlusions and phyllotaxy, i.e., arrangements of leaves around the stem. The leaf cross-overs pose challenges to accurately track each leaf using single view image sequence. Thus, we introduce a novel automated leaf tracking algorithm using a graph theoretic approach by multi-view image sequence analysis based on the determination of leaf-tips and leaf-junctions in the 3D space. The basis of the leaf tracking algorithm is: the leaves emerge using bottom-up approach in the case of a maize plant, and the direction of leaf emergence strictly alternates in terms of direction. The algorithm involves labeling of the individual parts of a plant, i.e., leaves and stem, following graphical representation of the plant skeleton, i.e., one-pixel wide connected line obtained from the binary image. The length of the leaf is measured by the number of pixels in the leaf skeleton. To evaluate the performance of the algorithm, a benchmark dataset is indispensable. Thus, we publicly release University of Nebraska-Lincoln Component Plant Phenotyping dataset-2 (UNL-CPPD-2) consisting of images of the 20 maize plants captured by visible light camera of the Lemnatec Scanalyzer 3D high throughout plant phenotyping facility once daily for 60 days from 10 different views. The dataset is aimed to facilitate the development and evaluation of leaf tracking algorithms and their uniform comparisons.

  2. First data from IceAct, an imaging air Cherenkov telescope with SiPMs at the South Pole

    Energy Technology Data Exchange (ETDEWEB)

    Auffenberg, Jan; Bretz, Thomas; Hansmann, Bengt; Hansmann, Tim; Hebbeker, Thomas; Kemp, Julian; Middendorf, Lukas; Niggemann, Tim; Raedel, Leif; Schaufel, Merlin; Schumacher, Johannes; Stahlberg, Martin; Werhan, Ansgar; Wiebusch, Christopher [RWTH Aachen University (Germany)

    2016-07-01

    IceCube-Gen2 is planned to extend the IceCube Neutrino Observatory at the geographic South Pole. For neutrino astronomy, a large background-free sample of well-reconstructed astrophysical neutrinos is essential. The main background for this signal are muons and neutrinos which are produced in cosmic-ray air showers in the Earth's atmosphere. The coincident detection of these air showers by the surface detector IceTop has been proven to be a powerful veto for atmospheric neutrinos and muons in the field of view of the Southern Hemisphere. This motivates a large extension of IceTop to more efficiently detect cosmic rays, IceVeto. Part of these extension plans is an array of imaging air Cherenkov telescopes, IceAct. A first IceAct prototype is consisting of an SiPM camera and lens optics optimized for harsh environments. Compared to IceTop stations, these telescopes potentially lower the detection threshold for air showers at the cost of a lower duty cycle. We present first data, taken during the commissioning of an IceAct prototype in December 2015 at the South Pole.

  3. Generation of synthetic image sequences for the verification of matching and tracking algorithms for deformation analysis

    Science.gov (United States)

    Bethmann, F.; Jepping, C.; Luhmann, T.

    2013-04-01

    This paper reports on a method for the generation of synthetic image data for almost arbitrary static or dynamic 3D scenarios. Image data generation is based on pre-defined 3D objects, object textures, camera orientation data and their imaging properties. The procedure does not focus on the creation of photo-realistic images under consideration of complex imaging and reflection models as they are used by common computer graphics programs. In contrast, the method is designed with main emphasis on geometrically correct synthetic images without radiometric impact. The calculation process includes photogrammetric distortion models, hence cameras with arbitrary geometric imaging characteristics can be applied. Consequently, image sets can be created that are consistent to mathematical photogrammetric models to be used as sup-pixel accurate data for the assessment of high-precision photogrammetric processing methods. In the first instance the paper describes the process of image simulation under consideration of colour value interpolation, MTF/PSF and so on. Subsequently the geometric quality of the synthetic images is evaluated with ellipse operators. Finally, simulated image sets are used to investigate matching and tracking algorithms as they have been developed at IAPG for deformation measurement in car safety testing.

  4. PET Imaging Stability Measurements During Simultaneous Pulsing of Aggressive MR Sequences on the SIGNA PET/MR System.

    Science.gov (United States)

    Deller, Timothy W; Khalighi, Mohammad Mehdi; Jansen, Floris P; Glover, Gary H

    2018-01-01

    The recent introduction of simultaneous whole-body PET/MR scanners has enabled new research taking advantage of the complementary information obtainable with PET and MRI. One such application is kinetic modeling, which requires high levels of PET quantitative stability. To accomplish the required PET stability levels, the PET subsystem must be sufficiently isolated from the effects of MR activity. Performance measurements have previously been published, demonstrating sufficient PET stability in the presence of MR pulsing for typical clinical use; however, PET stability during radiofrequency (RF)-intensive and gradient-intensive sequences has not previously been evaluated for a clinical whole-body scanner. In this work, PET stability of the GE SIGNA PET/MR was examined during simultaneous scanning of aggressive MR pulse sequences. Methods: PET performance tests were acquired with MR idle and during simultaneous MR pulsing. Recent system improvements mitigating RF interference and gain variation were used. A fast recovery fast spin echo MR sequence was selected for high RF power, and an echo planar imaging sequence was selected for its high heat-inducing gradients. Measurements were performed to determine PET stability under varying MR conditions using the following metrics: sensitivity, scatter fraction, contrast recovery, uniformity, count rate performance, and image quantitation. A final PET quantitative stability assessment for simultaneous PET scanning during functional MRI studies was performed with a spiral in-and-out gradient echo sequence. Results: Quantitation stability of a 68 Ge flood phantom was demonstrated within 0.34%. Normalized sensitivity was stable during simultaneous scanning within 0.3%. Scatter fraction measured with a 68 Ge line source in the scatter phantom was stable within the range of 40.4%-40.6%. Contrast recovery and uniformity were comparable for PET images acquired simultaneously with multiple MR conditions. Peak noise equivalent count

  5. Folate conjugated Mn{sub 3}O{sub 4}@SiO{sub 2} nanoparticles for targeted magnetic resonance imaging in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xinyi [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Zhou, Zhiguo, E-mail: zgzhou@shnu.edu.cn [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Wang, Li; Tang, Caizhi; Yang, Hong [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Yang, Shiping, E-mail: shipingy@shnu.edu.cn [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); The Education Ministry Key Lab of Pesticide and Chemical Biology, South China Agricultural University, Guangzhou 510641 (China)

    2014-09-15

    Graphical abstract: The Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA has been used as a T{sub 1}-MRI probe for in vivo. - Highlights: • The PEG and FA modified Mn{sub 3}O{sub 4}@SiO{sub 2} nanoparticles (Mn{sub 3}O{sub 4}@SiO{sub 2}–FA) were prepared. • Mn{sub 3}O{sub 4}@SiO{sub 2}–FA exhibited the good colloidal stability in the simulated biological medium. • Mn{sub 3}O{sub 4}@SiO{sub 2}–FA showed the targeting ability to HeLa cells overexpressed the FA receptor. • The T{sub 1}-weighted magnetic resonance (MR) imaging demonstrated the targeting ability of Mn{sub 3}O{sub 4}@SiO{sub 2}–FA in vivo tumor. - Abstract: The monodisperse silica-coated manganese oxide nanoparticles (Mn{sub 3}O{sub 4}@SiO{sub 2} NPs) were synthesized via the high temperature pyrolysis approach and were aminated through silanization. The amine-functionalized Mn{sub 3}O{sub 4} NPs enabled the covalent conjugation of hydrophilic methoxypoly(ethylene glycol) (PEG) and the targeting ligand of folate (FA) onto their surface. The formed PEG and FA modified Mn{sub 3}O{sub 4} NPs (Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA) exhibited the good colloidal stability in the simulated biological medium and the targeting ability to HeLa cells overexpressed the FA receptor. The T{sub 1}-weighted magnetic resonance (MR) imaging and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis of Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA NPs further demonstrated their targeting ability in tumor.

  6. Fat suppression at 2D MR imaging of the hands: Dixon method versus CHESS technique and STIR sequence.

    Science.gov (United States)

    Kirchgesner, Thomas; Perlepe, Vasiliki; Michoux, Nicolas; Larbi, Ahmed; Vande Berg, Bruno

    2017-04-01

    To compare the effectiveness of fat suppression and the signal-to-noise ratio (SNR) of the Dixon method with those of the CHESS (Chemical Shift-Selective) technique and STIR (Short Tau Inversion Recovery) sequence in hands of normal subjects at 2D MR imaging. 14 healthy volunteers (mean age of 29.4 years) consented to have both hands prospectively imaged with SE T1 Dixon, T1 CHESS, T2 Dixon, T2 CHESS and STIR sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFS BM ) and soft tissues (EFS ST ) in 20 joints per subject. One radiologist measured the SNR in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects, paired t-test and observed agreement to assess differences in effectiveness of fat suppression, differences in SNR and inter-observer agreement. EFS BM was statistically significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for T2 CHESS (pCHESS and for T2 Dixon than for STIR (pCHESS (pCHESS technique at 2D T1-weighted MR imaging of the hands. At T2-weighted MR imaging, fat suppression is more effective with the Dixon method while SNR is higher with the CHESS technique. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Automatic internal crack detection from a sequence of infrared images with a triple-threshold Canny edge detector

    Science.gov (United States)

    Wang, Gaochao; Tse, Peter W.; Yuan, Maodan

    2018-02-01

    Visual inspection and assessment of the condition of metal structures are essential for safety. Pulse thermography produces visible infrared images, which have been widely applied to detect and characterize defects in structures and materials. When active thermography, a non-destructive testing tool, is applied, the necessity of considerable manual checking can be avoided. However, detecting an internal crack with active thermography remains difficult, since it is usually invisible in the collected sequence of infrared images, which makes the automatic detection of internal cracks even harder. In addition, the detection of an internal crack can be hindered by a complicated inspection environment. With the purpose of putting forward a robust and automatic visual inspection method, a computer vision-based thresholding method is proposed. In this paper, the image signals are a sequence of infrared images collected from the experimental setup with a thermal camera and two flash lamps as stimulus. The contrast of pixels in each frame is enhanced by the Canny operator and then reconstructed by a triple-threshold system. Two features, mean value in the time domain and maximal amplitude in the frequency domain, are extracted from the reconstructed signal to help distinguish the crack pixels from others. Finally, a binary image indicating the location of the internal crack is generated by a K-means clustering method. The proposed procedure has been applied to an iron pipe, which contains two internal cracks and surface abrasion. Some improvements have been made for the computer vision-based automatic crack detection methods. In the future, the proposed method can be applied to realize the automatic detection of internal cracks from many infrared images for the industry.

  8. Atomic and electronic structure of trilayer graphene/SiC(0001): Evidence of Strong Dependence on Stacking Sequence and charge transfer

    OpenAIRE

    Pierucci, Debora; Brumme, Thomas; Girard, Jean-Christophe; Calandra, Matteo; Silly, Mathieu G.; Sirotti, Fausto; Barbier, Antoine; Mauri, Francesco; Ouerghi, Abdelkarim

    2016-01-01

    International audience; The transport properties of few-layer graphene are the directly result of a peculiar band structure near the Dirac point. Here, for epitaxial graphene grown on SiC, we determine the effect of charge transfer from the SiC substrate on the local density of states (LDOS) of trilayer graphene using scaning tunneling microscopy/spectroscopy and angle resolved photoemission spectroscopy (ARPES). Different spectra are observed and are attributed to the existence of two stable...

  9. Simulated structure and imaging of NTCDI on Si(1 1 1)-7 × 7 : a combined STM, NC-AFM and DFT study

    Science.gov (United States)

    Jarvis, S. P.; Sweetman, A. M.; Lekkas, I.; Champness, N. R.; Kantorovich, L.; Moriarty, P.

    2015-02-01

    The adsorption of naphthalene tetracarboxylic diimide (NTCDI) on Si(1 1 1)-7 × 7 is investigated through a combination of scanning tunnelling microscopy (STM), noncontact atomic force microscopy (NC-AFM) and density functional theory (DFT) calculations. We show that NTCDI adopts multiple planar adsorption geometries on the Si(1 1 1)-7 × 7 surface which can be imaged with intramolecular bond resolution using NC-AFM. DFT calculations reveal adsorption is dominated by covalent bond formation between the molecular oxygen atoms and the surface silicon adatoms. The chemisorption of the molecule is found to induce subtle distortions to the molecular structure, which are observed in NC-AFM images.

  10. Effectiveness of the STIR turbo spin–echo sequence MR imaging in evaluation of lymphadenopathy in esophageal cancer

    International Nuclear Information System (INIS)

    Alper, Fatih; Turkyilmaz, Atila; Kurtcan, Serpil; Aydin, Yener; Onbas, Omer; Acemoglu, Hamit; Eroglu, Atilla

    2011-01-01

    Purpose: We have investigated the utility of the STIR TSE sequence in the differentiation of benign from malignant mediastinal lymph nodes in patients with esophageal cancer. Patients and methods: This study included 35 consecutive patients who were diagnosed as esophageal cancer and were undergone surgery. STIR TSE sequences were obtained as the ECG trigger. The signal intensity of the benign and malign lymph nodes, normal esophagus, and pathologic esophagus can be calculated on STIR sequence. Results: Pathologically, the number of total lymph nodes in 35 operated cases was 482. Approximately 152 lymph nodes were detected with MR imaging. Of these, 28 were thought to be malignant, and 124 were thought to be benign, although 32 were malignant and 120 were benign according pathological results. The ratio of benign lymph node intensity value to normal esophagus intensity value was 0.73 ± 0.3. The ratio of malignant lymph node intensity value to normal esophagus intensity value ratio was 2.03 ± 0.4. According to these results, the sensitivity of MR was 81.3%, the specificity was 98.3%. Conclusion: We think that if motionless images can be obtained with MRI, we may be able to differentiate benign lymph nodes from malignant ones.

  11. An Improved Image Encryption Algorithm Based on Cyclic Rotations and Multiple Chaotic Sequences: Application to Satellite Images

    Directory of Open Access Journals (Sweden)

    MADANI Mohammed

    2017-10-01

    Full Text Available In this paper, a new satellite image encryption algorithm based on the combination of multiple chaotic systems and a random cyclic rotation technique is proposed. Our contribution consists in implementing three different chaotic maps (logistic, sine, and standard combined to improve the security of satellite images. Besides enhancing the encryption, the proposed algorithm also focuses on advanced efficiency of the ciphered images. Compared with classical encryption schemes based on multiple chaotic maps and the Rubik's cube rotation, our approach has not only the same merits of chaos systems like high sensitivity to initial values, unpredictability, and pseudo-randomness, but also other advantages like a higher number of permutations, better performances in Peak Signal to Noise Ratio (PSNR and a Maximum Deviation (MD.

  12. Performance Study of an aSi Flat Panel Detector for Fast Neutron Imaging of Nuclear Waste

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, M.; Mauerhofer, E. [Institute of Energy and Climate Research - Nuclear Waste Management and Reactor Safety, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Engels, R.; Kemmerling, G. [Central Institute for Engineering, Electronics and Analytics - Electronic Systems, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Frank, M. [MATHCCES - Department of Mathematics, RWTH Aachen University, 52062 Aachen (Germany); Havenith, A.; Kettler, J.; Klapdor-Kleingrothaus, T. [Institute of Nuclear Engineering and Technology Transfer, RWTH Aachen University, 52062 Aachen (Germany); Schitthelm, O. [Corporate Technology, Siemens AG, 91058 Erlangen (Germany)

    2015-07-01

    Radioactive waste must be characterized to check its conformance for intermediate storage and final disposal according to national regulations. For the determination of radio-toxic and chemo-toxic contents of radioactive waste packages non-destructive analytical techniques are preferentially used. Fast neutron imaging is a promising technique to assay large and dense items providing, in complementarity to photon imaging, additional information on the presence of structures in radioactive waste packages. Therefore the feasibility of a compact Neutron Imaging System for Radioactive waste Analysis (NISRA) using 14 MeV neutrons is studied in a cooperation framework of Forschungszentrum Juelich GmbH, RWTH Aachen University and Siemens AG. However due to the low neutron emission of neutron generators in comparison to research reactors the challenging task resides in the development of an imaging detector with a high efficiency, a low sensitivity to gamma radiation and a resolution sufficient for the purpose. The setup is composed of a commercial D-T neutron generator (Genie16GT, Sodern) with a surrounding shielding made of polyethylene, which acts as a collimator and an amorphous silicon flat panel detector (aSi, 40 x 40 cm{sup 2}, XRD-1642, Perkin Elmer). Neutron detection is achieved using a general propose plastic scintillator (EJ-260, Eljen Technology) linked to the detector. The thermal noise of the photodiodes is reduced by employing an entrance window made of aluminium. Optimal gain and integration time for data acquisition are set by measuring the response of the detector to the radiation of a 500 MBq {sup 241}Am-source. Detector performance was studied by recording neutron radiography images of materials with various, but well known, chemical compositions, densities and dimensions (Al, C, Fe, Pb, W, concrete, polyethylene, 5 x 8 x 10 cm{sup 3}). To simulate gamma-ray emitting waste radiographs in presence of a gamma-ray sources ({sup 60}Co, {sup 137}Cs, {sup 241

  13. Effects of imaging gradients in sequences with varying longitudinal storage time-Case of diffusion exchange imaging

    DEFF Research Database (Denmark)

    Lasic, Samo; Lundell, Henrik; Topgaard, Daniel

    2017-01-01

    low-pass diffusion filtering during the LS interval, which is more pronounced at lower exchange rates. For a total exchange rate constant larger than 1 s-1, the AXR bias is expected to be negligible when slices thicker than 2.5mm are used. Conclusion: In correlation experiments like FEXI, relying...... on LS with variable duration, imaging gradients may cause disrupting effects that cannot be easily mitigated and should be carefully considered for unbiased results. In typical clinical applications of FEXI, the imaging gradients are expected to cause a negligible AXR bias. However, the AXR bias may...

  14. Usefulness of low-field FlAIR sequence in MR imaging of intracranial tumors

    International Nuclear Information System (INIS)

    Sokolowska, D.; Sasiadek, M.; Zimny, A.

    2004-01-01

    Plain MR study is often insufficient for visualization of all important details of intracranial tumors, hence there are attempts to use supplementary MR techniques. One of them is FLAIR (fluid attenuated inversion recovery) sequence which previously was available only in high-field MR units, but recently has been introduced also in less expensive low-field units. FLAIR is already widely used in the diagnostics of ischemic and demyelinating lesions, while there are few papers concerning its application in intracranial tumors, none of them regarding low-field MR units.The aim of our study was detailed evaluation of low-field FLAIR in the diagnostics of intracranial tumors. The material consisted of 76 patients with intracranial tumors, who were examined with low-field open MR unit (0.23 Tesla). In all patients, standard T2-weighted and T1-weighted (before and after contrast enhancement) sequences, as well as FLAIR sequence, were performed. The following symptoms were compared in the aforementioned sequences: tumor-edema, edema-brain and tumor-brain borders, visualization of tumour structure, vessels in the tumor area and precise tumor localization. A superiority of FLAIR in assessment of all symptoms has been confirmed, at least in part of the patient group. It concerned particularly the evaluation of brain-edema and edema-brain borders which were better visible with FLAIR than with all other sequences in 29 and 30 patients, respectively. In the assessment of the remaining symptoms (tumor-brain border, tumor structure, visualization of vessels, tumor localization) FLAIR was superior to other sequences in smaller number of patients (13,11,11 and 12, respectively). Totally, in 48 out of 76 patients (63.2%) FLAIR allowed better assessment of at least one of the analyzed symptoms. Low-field MR FLAIR enriches diagnostic information in majority of patients with intracranial tumors, therefore it should be included routinely in the diagnostic algorithm in this group of

  15. Performance of Correspondence Algorithms in Vision-Based Driver Assistance Using an Online Image Sequence Database

    DEFF Research Database (Denmark)

    Klette, Reinhard; Krüger, Norbert; Vaudrey, Tobi

    2011-01-01

    the classification of recorded video data into situations defined by a cooccurrence of some events in recorded traffic scenes. About 100-400 stereo frames (or 4-16 s of recording) are considered a basic sequence, which will be identified with one particular situation. Future testing is expected to be on data...

  16. Short term reproducibility of a high contrast 3-D isotropic optic nerve imaging sequence in healthy controls

    Science.gov (United States)

    Harrigan, Robert L.; Smith, Alex K.; Mawn, Louise A.; Smith, Seth A.; Landman, Bennett A.

    2016-03-01

    The optic nerve (ON) plays a crucial role in human vision transporting all visual information from the retina to the brain for higher order processing. There are many diseases that affect the ON structure such as optic neuritis, anterior ischemic optic neuropathy and multiple sclerosis. Because the ON is the sole pathway for visual information from the retina to areas of higher level processing, measures of ON damage have been shown to correlate well with visual deficits. Increased intracranial pressure has been shown to correlate with the size of the cerebrospinal fluid (CSF) surrounding the ON. These measures are generally taken at an arbitrary point along the nerve and do not account for changes along the length of the ON. We propose a high contrast and high-resolution 3-D acquired isotropic imaging sequence optimized for ON imaging. We have acquired scan-rescan data using the optimized sequence and a current standard of care protocol for 10 subjects. We show that this sequence has superior contrast-to-noise ratio to the current standard of care while achieving a factor of 11 higher resolution. We apply a previously published automatic pipeline to segment the ON and CSF sheath and measure the size of each individually. We show that these measures of ON size have lower short- term reproducibility than the population variance and the variability along the length of the nerve. We find that the proposed imaging protocol is (1) useful in detecting population differences and local changes and (2) a promising tool for investigating biomarkers related to structural changes of the ON.

  17. Hepatic adenomatosis: rapid sequence MR imaging following gadolinium enhancement: a case report

    International Nuclear Information System (INIS)

    Brummett, D.; Burton, E.M.; Sabio, H.

    1999-01-01

    Hepatic adenomas are primary liver tumors usually associated with underlying metabolic disease or with anabolic steroid or oral contraceptive use. Hepatic adenomatosis (HA) is defined as the presence of more than four adenomas. Only 13 cases of HA have been reported in patients without glycogen storage disease or steroid use. We report a case of HA imaged by postcontrast T1-weighted images obtained during a breath-holding series. The lesions were most conspicuous 3-4 min after contrast administration; 4 of the 5 tumors were not identified on T2-weighted images. Unlike previous reports of HA in which the lesions remained hyperintense during sequential postcontrast imaging, the smaller lesions in this case demonstrated contrast washout, thereby distinguishing them from hemangiomata. (orig.)

  18. Pulse sequence optimization for superparamagnetic iron oxide-enhaced MR imaging in the detection of hepatic VX2 tumors in rabbits

    International Nuclear Information System (INIS)

    Jang, Hyun Jung; Han, Joon Koo; Lee, Kyoung Ho; Kim, Se Hyung; Choi, Byung Ihn; Kim, Tae Kyoung

    2003-01-01

    The purpose of this experimental study was to determine the optimal pulse sequences for SPIO-enhanced MR imaging in the evaluation of multiple hepatic tumors. Twelve rabbits with multiple VX2 liver tumors underwent SPOI-enhanced MRI using the following nine pulse sequences: TSE T2-weighted imaging (T2W1), TSE proton density-weighted imaging(PDWI), and GRE T2*-weighted imaging (T2*W1) with seven different echo times (TE). Liver-lesion contrast-to-noise ratios (CNRs) were calculated, and images were also assessed qualitatively by two radiologists, who reached a consensus as to lesion conspicuity and imaging artifacts using a four-level scale. By means of pathologic correlation, the sensitivity and positive predictive value of each sequence was calculated. TSE T2W1 and long-TE (35 msec) FLASH T2*W1 showed the highest liver-lesion CNR. The best lesion conspicuity was seen at TSE T2W1 and medium-TE (12 msec) GRE T2*W1. Short TE GRE T2*W1 showed the least imaging artifacts. The four sequences which demonstrated the best sensitivity were medium-TE (12 msec), GRE T2*W1 (FLASH, 84%; FISP, 82%), TSE W2T1 (79%), and TSE PDWI (76%). All nine sequences showed overall high positive predictive value (86-97%), with no statistically significant difference (p>0.05). In terms of image quality and the detection of sensitivity, TSE T2W1 and medium TE (12 msec) GRE T2*W1 were the top two pulse sequences among the various sequences used for no SPIO-enhanced MRI. They are thus considered to be optimal sequences for evaluating multiple malignant hepatic tumors

  19. SEGMENTATION OF ENVIRONMENTAL TIME LAPSE IMAGE SEQUENCES FOR THE DETERMINATION OF SHORE LINES CAPTURED BY HAND-HELD SMARTPHONE CAMERAS

    Directory of Open Access Journals (Sweden)

    M. Kröhnert

    2017-09-01

    Full Text Available The relevance of globally environmental issues gains importance since the last years with still rising trends. Especially disastrous floods may cause in serious damage within very short times. Although conventional gauging stations provide reliable information about prevailing water levels, they are highly cost-intensive and thus just sparsely installed. Smartphones with inbuilt cameras, powerful processing units and low-cost positioning systems seem to be very suitable wide-spread measurement devices that could be used for geo-crowdsourcing purposes. Thus, we aim for the development of a versatile mobile water level measurement system to establish a densified hydrological network of water levels with high spatial and temporal resolution. This paper addresses a key issue of the entire system: the detection of running water shore lines in smartphone images. Flowing water never appears equally in close-range images even if the extrinsics remain unchanged. Its non-rigid behavior impedes the use of good practices for image segmentation as a prerequisite for water line detection. Consequently, we use a hand-held time lapse image sequence instead of a single image that provides the time component to determine a spatio-temporal texture image. Using a region growing concept, the texture is analyzed for immutable shore and dynamic water areas. Finally, the prevalent shore line is examined by the resultant shapes. For method validation, various study areas are observed from several distances covering urban and rural flowing waters with different characteristics. Future work provides a transformation of the water line into object space by image-to-geometry intersection.

  20. Inter-slice bidirectional registration-based segmentation of the prostate gland in MR and CT image sequences

    Energy Technology Data Exchange (ETDEWEB)

    Khalvati, Farzad, E-mail: farzad.khalvati@uwaterloo.ca; Tizhoosh, Hamid R. [Department of Systems Design Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Salmanpour, Aryan; Rahnamayan, Shahryar [Department of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, Ontario L1H 7K4 (Canada); Rodrigues, George [Department of Radiation Oncology, London Regional Cancer Program, London, Ontario N6C 2R6, Canada and Department of Epidemiology/Biostatistics, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

    2013-12-15

    Purpose: Accurate segmentation and volume estimation of the prostate gland in magnetic resonance (MR) and computed tomography (CT) images are necessary steps in diagnosis, treatment, and monitoring of prostate cancer. This paper presents an algorithm for the prostate gland volume estimation based on the semiautomated segmentation of individual slices in T2-weighted MR and CT image sequences. Methods: The proposedInter-Slice Bidirectional Registration-based Segmentation (iBRS) algorithm relies on interslice image registration of volume data to segment the prostate gland without the use of an anatomical atlas. It requires the user to mark only three slices in a given volume dataset, i.e., the first, middle, and last slices. Next, the proposed algorithm uses a registration algorithm to autosegment the remaining slices. We conducted comprehensive experiments to measure the performance of the proposed algorithm using three registration methods (i.e., rigid, affine, and nonrigid techniques). Results: The results with the proposed technique were compared with manual marking using prostate MR and CT images from 117 patients. Manual marking was performed by an expert user for all 117 patients. The median accuracies for individual slices measured using the Dice similarity coefficient (DSC) were 92% and 91% for MR and CT images, respectively. The iBRS algorithm was also evaluated regarding user variability, which confirmed that the algorithm was robust to interuser variability when marking the prostate gland. Conclusions: The proposed algorithm exploits the interslice data redundancy of the images in a volume dataset of MR and CT images and eliminates the need for an atlas, minimizing the computational cost while producing highly accurate results which are robust to interuser variability.

  1. High-accuracy and robust face recognition system based on optical parallel correlator using a temporal image sequence

    Science.gov (United States)

    Watanabe, Eriko; Ishikawa, Mami; Ohta, Maiko; Kodate, Kashiko

    2005-09-01

    Face recognition is used in a wide range of security systems, such as monitoring credit card use, searching for individuals with street cameras via Internet and maintaining immigration control. There are still many technical subjects under study. For instance, the number of images that can be stored is limited under the current system, and the rate of recognition must be improved to account for photo shots taken at different angles under various conditions. We implemented a fully automatic Fast Face Recognition Optical Correlator (FARCO) system by using a 1000 frame/s optical parallel correlator designed and assembled by us. Operational speed for the 1: N (i.e. matching a pair of images among N, where N refers to the number of images in the database) identification experiment (4000 face images) amounts to less than 1.5 seconds, including the pre/post processing. From trial 1: N identification experiments using FARCO, we acquired low error rates of 2.6% False Reject Rate and 1.3% False Accept Rate. By making the most of the high-speed data-processing capability of this system, much more robustness can be achieved for various recognition conditions when large-category data are registered for a single person. We propose a face recognition algorithm for the FARCO while employing a temporal image sequence of moving images. Applying this algorithm to a natural posture, a two times higher recognition rate scored compared with our conventional system. The system has high potential for future use in a variety of purposes such as search for criminal suspects by use of street and airport video cameras, registration of babies at hospitals or handling of an immeasurable number of images in a database.

  2. Segmentation of Environmental Time Lapse Image Sequences for the Determination of Shore Lines Captured by Hand-Held Smartphone Cameras

    Science.gov (United States)

    Kröhnert, M.; Meichsner, R.

    2017-09-01

    The relevance of globally environmental issues gains importance since the last years with still rising trends. Especially disastrous floods may cause in serious damage within very short times. Although conventional gauging stations provide reliable information about prevailing water levels, they are highly cost-intensive and thus just sparsely installed. Smartphones with inbuilt cameras, powerful processing units and low-cost positioning systems seem to be very suitable wide-spread measurement devices that could be used for geo-crowdsourcing purposes. Thus, we aim for the development of a versatile mobile water level measurement system to establish a densified hydrological network of water levels with high spatial and temporal resolution. This paper addresses a key issue of the entire system: the detection of running water shore lines in smartphone images. Flowing water never appears equally in close-range images even if the extrinsics remain unchanged. Its non-rigid behavior impedes the use of good practices for image segmentation as a prerequisite for water line detection. Consequently, we use a hand-held time lapse image sequence instead of a single image that provides the time component to determine a spatio-temporal texture image. Using a region growing concept, the texture is analyzed for immutable shore and dynamic water areas. Finally, the prevalent shore line is examined by the resultant shapes. For method validation, various study areas are observed from several distances covering urban and rural flowing waters with different characteristics. Future work provides a transformation of the water line into object space by image-to-geometry intersection.

  3. Inter-slice bidirectional registration-based segmentation of the prostate gland in MR and CT image sequences

    International Nuclear Information System (INIS)

    Khalvati, Farzad; Tizhoosh, Hamid R.; Salmanpour, Aryan; Rahnamayan, Shahryar; Rodrigues, George

    2013-01-01

    Purpose: Accurate segmentation and volume estimation of the prostate gland in magnetic resonance (MR) and computed tomography (CT) images are necessary steps in diagnosis, treatment, and monitoring of prostate cancer. This paper presents an algorithm for the prostate gland volume estimation based on the semiautomated segmentation of individual slices in T2-weighted MR and CT image sequences. Methods: The proposedInter-Slice Bidirectional Registration-based Segmentation (iBRS) algorithm relies on interslice image registration of volume data to segment the prostate gland without the use of an anatomical atlas. It requires the user to mark only three slices in a given volume dataset, i.e., the first, middle, and last slices. Next, the proposed algorithm uses a registration algorithm to autosegment the remaining slices. We conducted comprehensive experiments to measure the performance of the proposed algorithm using three registration methods (i.e., rigid, affine, and nonrigid techniques). Results: The results with the proposed technique were compared with manual marking using prostate MR and CT images from 117 patients. Manual marking was performed by an expert user for all 117 patients. The median accuracies for individual slices measured using the Dice similarity coefficient (DSC) were 92% and 91% for MR and CT images, respectively. The iBRS algorithm was also evaluated regarding user variability, which confirmed that the algorithm was robust to interuser variability when marking the prostate gland. Conclusions: The proposed algorithm exploits the interslice data redundancy of the images in a volume dataset of MR and CT images and eliminates the need for an atlas, minimizing the computational cost while producing highly accurate results which are robust to interuser variability

  4. Detection of Subarachnoid Hemorrhage at Acute and Subacute/Chronic Stages: Comparison of Four Magnetic Resonance Imaging Pulse Sequences and Computed Tomography

    Directory of Open Access Journals (Sweden)

    Mei-Kang Yuan

    2005-03-01

    Conclusion: FLAIR and GE T2* MRI pulse sequences, and CT scans, are all statistically significant indicators of acute SAH. GE T2*-weighted images are statistically significant indicators of subacute-to-chronic SAH, whereas other MRI pulse sequences, and CT scans, are not.

  5. DIfferential Subsampling with Cartesian Ordering (DISCO): a high spatio-temporal resolution Dixon imaging sequence for multiphasic contrast enhanced abdominal imaging.

    Science.gov (United States)

    Saranathan, Manojkumar; Rettmann, Dan W; Hargreaves, Brian A; Clarke, Sharon E; Vasanawala, Shreyas S

    2012-06-01

    To develop and evaluate a multiphasic contrast-enhanced MRI method called DIfferential Sub-sampling with Cartesian Ordering (DISCO) for abdominal imaging. A three-dimensional, variable density pseudo-random k-space segmentation scheme was developed and combined with a Dixon-based fat-water separation algorithm to generate high temporal resolution images with robust fat suppression and without compromise in spatial resolution or coverage. With institutional review board approval and informed consent, 11 consecutive patients referred for abdominal MRI at 3 Tesla (T) were imaged with both DISCO and a routine clinical three-dimensional SPGR-Dixon (LAVA FLEX) sequence. All images were graded by two radiologists using quality of fat suppression, severity of artifacts, and overall image quality as scoring criteria. For assessment of arterial phase capture efficiency, the number of temporal phases with angiographic phase and hepatic arterial phase was recorded. There were no significant differences in quality of fat suppression, artifact severity or overall image quality between DISCO and LAVA FLEX images (P > 0.05, Wilcoxon signed rank test). The angiographic and arterial phases were captured in all 11 patients scanned using the DISCO acquisition (mean number of phases were two and three, respectively). DISCO effectively captures the fast dynamics of abdominal pathology such as hyperenhancing hepatic lesions with a high spatio-temporal resolution. Typically, 1.1 × 1.5 × 3 mm spatial resolution over 60 slices was achieved with a temporal resolution of 4-5 s. Copyright © 2012 Wiley Periodicals, Inc.

  6. Breast MRI at very short TE (minTE). Image analysis of minTE sequences on non-fat-saturated, subtracted T1-weighted images

    International Nuclear Information System (INIS)

    Wenkel, Evelyn; Janka, Rolf; Kaemmerer, Nadine; Uder, Michael; Hammon, Matthias; Brand, Michael; Hartmann, Arndt

    2017-01-01

    The aim was to evaluate a minimum echo time (minTE) protocol for breast magnetic resonance imaging (MRI) in patients with breast lesions compared to a standard TE (nTE) time protocol. Breasts of 144 women were examined with a 1.5 Tesla MRI scanner. Additionally to the standard gradient-echo sequence with nTE (4.8 ms), a variant with minimum TE (1.2 ms) was used in an interleaved fashion which leads to a better temporal resolution and should reduce the scan time by approximately 50%. Lesion sizes were measured and the signal-to-noise ratio (SNR) as well as the contrast-to-noise ratio (CNR) were calculated. Subjective confidence was evaluated using a 3-point scale before looking at the nTE sequences (1 = very sure that I can identify a lesion and classify it, 2 = quite sure that I can identify a lesion and classify it, 3 = definitely want to see nTE for final assessment) and the subjective image quality of all examinations was evaluated using a four-grade scale (1 = sharp, 2 = slight blur, 3 = moderate blur and 4 = severe blur/not evaluable) for lesion and skin sharpness. Lesion morphology and contrast enhancement were also evaluated. With minTE sequences, no lesion was rated with ''definitely want to see nTE sequences for final assessment''. The difference of the longitudinal and transverse diameter did not differ significantly (p>0.05). With minTE, lesions and skin were rated to be significantly more blurry (p<0.01 for lesions and p<0.05 for skin). There was no difference between both sequences with respect to SNR, CNR, lesion morphology, contrast enhancement and detection of multifocal disease. Dynamic breast MRI with a minTE protocol is feasible without a major loss of information (SNR, CNR, lesion morphology, contrast enhancement and lesion sizes) and the temporal resolution can be increased by a factor of 2 using minTE sequences.

  7. Breast MRI at very short TE (minTE). Image analysis of minTE sequences on non-fat-saturated, subtracted T1-weighted images

    Energy Technology Data Exchange (ETDEWEB)

    Wenkel, Evelyn; Janka, Rolf; Kaemmerer, Nadine; Uder, Michael; Hammon, Matthias; Brand, Michael [Univ. Hospital Erlangen (Germany). Dept. of Radiology; Geppert, Christian [Siemens Healthcare GmbH, Erlangen (Germany); Hartmann, Arndt [Univ. Hospital Erlangen (Germany). Dept. of Pathology

    2017-02-15

    The aim was to evaluate a minimum echo time (minTE) protocol for breast magnetic resonance imaging (MRI) in patients with breast lesions compared to a standard TE (nTE) time protocol. Breasts of 144 women were examined with a 1.5 Tesla MRI scanner. Additionally to the standard gradient-echo sequence with nTE (4.8 ms), a variant with minimum TE (1.2 ms) was used in an interleaved fashion which leads to a better temporal resolution and should reduce the scan time by approximately 50%. Lesion sizes were measured and the signal-to-noise ratio (SNR) as well as the contrast-to-noise ratio (CNR) were calculated. Subjective confidence was evaluated using a 3-point scale before looking at the nTE sequences (1 = very sure that I can identify a lesion and classify it, 2 = quite sure that I can identify a lesion and classify it, 3 = definitely want to see nTE for final assessment) and the subjective image quality of all examinations was evaluated using a four-grade scale (1 = sharp, 2 = slight blur, 3 = moderate blur and 4 = severe blur/not evaluable) for lesion and skin sharpness. Lesion morphology and contrast enhancement were also evaluated. With minTE sequences, no lesion was rated with ''definitely want to see nTE sequences for final assessment''. The difference of the longitudinal and transverse diameter did not differ significantly (p>0.05). With minTE, lesions and skin were rated to be significantly more blurry (p<0.01 for lesions and p<0.05 for skin). There was no difference between both sequences with respect to SNR, CNR, lesion morphology, contrast enhancement and detection of multifocal disease. Dynamic breast MRI with a minTE protocol is feasible without a major loss of information (SNR, CNR, lesion morphology, contrast enhancement and lesion sizes) and the temporal resolution can be increased by a factor of 2 using minTE sequences.

  8. Identification Of Barley Grain Mycoflora By Next Generation Sequencing And Videometer Multispectral Imaging

    DEFF Research Database (Denmark)

    Jørgensen, Johannes Ravn; Carstensen, Jens Michael; Søren, Knudsen

    ) in the reflectance mode (5 Mpix per band, pixel size app. 45 μm x 45 μm). Spectral information over the surface of seeds may be combined with information about size, shape, and texture of the seeds. This information links detection of fungal infection with other seed characteristics known from general seed testing...... species in the genus produce mycotoxins responsible for serious quality deterioration. In malting barley, Fusarium also has a negative effect by causing gushing in beer. A number of barley seeds (app. 200) assumed to be infected by fungal from different origins and years of cultivation were tested by NGS...... sequencing the ITS (Internal Transcribed Spacer) region from total DNA. Approximately 2-4000 sequences were obtained from each seed and these were subsequently identified to species level in order to give an exact identification of fungal genera on each seed. The main fungal genera identified were Fusarium...

  9. Magnetic resonance imaging of metal artifact reduction sequences in the assessment of metal-on-metal hip prostheses

    Directory of Open Access Journals (Sweden)

    Aboelmagd SM

    2014-05-01

    Full Text Available Sharief M Aboelmagd, Paul N Malcolm, Andoni P Toms Department of Radiology, Norfolk and Norwich University Hospital National Health Service Trust, Norwich, UK Abstract: Recent developments in metal artifact reduction techniques in magnetic resonance (MR have, in large part, been stimulated by the advent of soft tissue complications associated with modern metal-on-metal total hip replacements. Metallic orthopedic implants can result in severe degradation of MR images because ferromagnetic susceptibility causes signal loss, signal pile-up, geometric distortion, and failure of fat suppression. There are several approaches to controlling these susceptibility artifacts. Standard fast spin echo sequences can be adapted by modifying echo times, matrix, receiver bandwidth, slice thickness, and echo trains to minimize frequency encoding misregistration. Short tau inversion recovery and 2-point Dixon techniques are both more resistant to susceptibility artifacts than spectral fat suppression. A number of dedicated metal artifact reduction sequences are now available commercially. The common approach of these multispectral techniques is to generate three dimensional datasets from which the final images are reconstructed. Frequency encoding misregistration is controlled using a variety of techniques, including specific resonant frequency acquisition, view-angle tilting, and phase encoding. Metal artifact reduction MR imaging has been the key to understanding the prevalence, severity, and prognosis of adverse reactions to metal debris in metal-on-metal hip replacements. Conventional radiographs are typically normal or demonstrate minimal change and are unable to demonstrate the often extensive soft tissue abnormalities, which include necrosis, soft tissue masses and fluid collections, myositis, muscle atrophy, tendon avulsions, and osteonecrosis. These MR findings correlate poorly with clinical and serological measures of disease, and therefore MR imaging is

  10. Automatic classification of minimally invasive instruments based on endoscopic image sequences

    Science.gov (United States)

    Speidel, Stefanie; Benzko, Julia; Krappe, Sebastian; Sudra, Gunther; Azad, Pedram; Müller-Stich, Beat Peter; Gutt, Carsten; Dillmann, Rüdiger

    2009-02-01

    Minimally invasive surgery is nowadays a frequently applied technique and can be regarded as a major breakthrough in surgery. The surgeon has to adopt special operation-techniques and deal with difficulties like the complex hand-eye coordination and restricted mobility. To alleviate these constraints we propose to enhance the surgeon's capabilities by providing a context-aware assistance using augmented reality techniques. To analyze the current situation for context-aware assistance, we need intraoperatively gained sensor data and a model of the intervention. A situation consists of information about the performed activity, the used instruments, the surgical objects, the anatomical structures and defines the state of an intervention for a given moment in time. The endoscopic images provide a rich source of information which can be used for an image-based analysis. Different visual cues are observed in order to perform an image-based analysis with the objective to gain as much information as possible about the current situation. An important visual cue is the automatic recognition of the instruments which appear in the scene. In this paper we present the classification of minimally invasive instruments using the endoscopic images. The instruments are not modified by markers. The system segments the instruments in the current image and recognizes the instrument type based on three-dimensional instrument models.

  11. Fully automated motion correction in first-pass myocardial perfusion MR image sequences.

    Science.gov (United States)

    Milles, Julien; van der Geest, Rob J; Jerosch-Herold, Michael; Reiber, Johan H C; Lelieveldt, Boudewijn P F

    2008-11-01

    This paper presents a novel method for registration of cardiac perfusion magnetic resonance imaging (MRI). The presented method is capable of automatically registering perfusion data, using independent component analysis (ICA) to extract physiologically relevant features together with their time-intensity behavior. A time-varying reference image mimicking intensity changes in the data of interest is computed based on the results of that ICA. This reference image is used in a two-pass registration framework. Qualitative and quantitative validation of the method is carried out using 46 clinical quality, short-axis, perfusion MR datasets comprising 100 images each. Despite varying image quality and motion patterns in the evaluation set, validation of the method showed a reduction of the average right ventricle (LV) motion from 1.26+/-0.87 to 0.64+/-0.46 pixels. Time-intensity curves are also improved after registration with an average error reduced from 2.65+/-7.89% to 0.87+/-3.88% between registered data and manual gold standard. Comparison of clinically relevant parameters computed using registered data and the manual gold standard show a good agreement. Additional tests with a simulated free-breathing protocol showed robustness against considerable deviations from a standard breathing protocol. We conclude that this fully automatic ICA-based method shows an accuracy, a robustness and a computation speed adequate for use in a clinical environment.

  12. Clinical evaluation of fat suppressed fast-SPGR sequence of the breast MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Mitsuyuki; Hasegawa, Makoto; Matsubara, Tadashi [Yokohama Sakae Kyosai Hospital (Japan)

    1998-05-01

    MR-mammography by fat suppressed Fast-SPGR was evaluated for diagnosis and determination of invasion of tumor. Dynamic MRIs were performed in 12 phases, such as, before infusion of contrast media, right after and one to ten minutes after infusion with interval of one minute. In 15 patients (breast cancer, fibroadenoma, lymphocytic lobulitits and cystic intraductal papilloma), underwent MRI, the images were compared with pathological findings. Ten cases were confirmed as malignancy among 11 cases of breast cancer (sensitivity 91%). Eleven cases were confirmed as breast cancer among 12 cases diagnosed as breast cancer by MRI (specificity 92%). In 12 of all 15 cases, benignity or malignancy was checked correctly (accuracy 80%). Invasion of breast cancer was defined as the deep color dyeing area which was neighbored with the tumor in early stage of cystography. Eight of 11 cases were diagnosed precisely with fat suppression image, and nine were by subtraction image. Diagnosis was possible only by subtraction image in a case of scirrhous carcinoma accompanied with intradutal invasion. The area of invasion was not defined correctly in the case accompanied by mastopathy. It is difficult to evaluate benignity or malignancy of mammary gland tumor only by dynamic MRI, it is necessary to diagnose the shape and deep color image of tumor generally. (K.H.)

  13. Spatio-temporal Hotelling observer for signal detection from image sequences.

    Science.gov (United States)

    Caucci, Luca; Barrett, Harrison H; Rodriguez, Jeffrey J

    2009-06-22

    Detection of signals in noisy images is necessary in many applications, including astronomy and medical imaging. The optimal linear observer for performing a detection task, called the Hotelling observer in the medical literature, can be regarded as a generalization of the familiar prewhitening matched filter. Performance on the detection task is limited by randomness in the image data, which stems from randomness in the object, randomness in the imaging system, and randomness in the detector outputs due to photon and readout noise, and the Hotelling observer accounts for all of these effects in an optimal way. If multiple temporal frames of images are acquired, the resulting data set is a spatio-temporal random process, and the Hotelling observer becomes a spatio-temporal linear operator. This paper discusses the theory of the spatio-temporal Hotelling observer and estimation of the required spatio-temporal covariance matrices. It also presents a parallel implementation of the observer on a cluster of Sony PLAYSTATION 3 gaming consoles. As an example, we consider the use of the spatio-temporal Hotelling observer for exoplanet detection.

  14. Three-dimensional gradient echo versus spin echo sequence in contrast-enhanced imaging of the pituitary gland at 3 T

    Energy Technology Data Exchange (ETDEWEB)

    Kakite, Suguru, E-mail: sugkaki@med.tottori-u.ac.jp [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishicho, Yonago 683-8503 (Japan); Fujii, Shinya [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishicho, Yonago 683-8503 (Japan); Kurosaki, Masamichi [Department of Neurosurgery, Faculty of Medicine, Tottori University, 36-1, Nishicho, Yonago 683-8503 (Japan); Kanasaki, Yoshiko; Matsusue, Eiji; Kaminou, Toshio; Ogawa, Toshihide [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishicho, Yonago 683-8503 (Japan)

    2011-07-15

    Introduction: To clarify whether a three-dimensional-gradient echo (3D-GRE) or spin echo (SE) sequence is more useful for evaluating sellar lesions on contrast-enhanced T1-weighted MR imaging at 3.0 Tesla (T). Methods: We retrospectively assessed contrast-enhanced T1-weighted images using 3D-GRE and SE sequences at 3.0 T obtained from 33 consecutive patients with clinically suspected sellar lesions. Two experienced neuroradiologists evaluated the images qualitatively in terms of the following criteria: boundary edge of the cavernous sinus and pituitary gland, border of sellar lesions, delineation of the optic nerve and cranial nerves within the cavernous sinus, susceptibility and flow artifacts, and overall image quality. Results: At 3.0 T, 3D-GRE provided significantly better images than the SE sequence in terms of the border of sellar lesions, delineation of cranial nerves, and overall image quality; there was no significant difference regarding the boundary edge of the cavernous sinus and pituitary gland. In addition, the 3D-GRE sequence showed fewer pulsation artifacts but more susceptibility artifacts. Conclusion: Our results indicate that 3D-GRE is the more suitable sequence for evaluating sellar lesions on contrast-enhanced T1-weighted imaging at 3.0 T.

  15. A flexible new method for 3D measurement based on multi-view image sequences

    Science.gov (United States)

    Cui, Haihua; Zhao, Zhimin; Cheng, Xiaosheng; Guo, Changye; Jia, Huayu

    2016-11-01

    Three-dimensional measurement is the base part for reverse engineering. The paper developed a new flexible and fast optical measurement method based on multi-view geometry theory. At first, feature points are detected and matched with improved SIFT algorithm. The Hellinger Kernel is used to estimate the histogram distance instead of traditional Euclidean distance, which is immunity to the weak texture image; then a new filter three-principle for filtering the calculation of essential matrix is designed, the essential matrix is calculated using the improved a Contrario Ransac filter method. One view point cloud is constructed accurately with two view images; after this, the overlapped features are used to eliminate the accumulated errors caused by added view images, which improved the camera's position precision. At last, the method is verified with the application of dental restoration CAD/CAM, experiment results show that the proposed method is fast, accurate and flexible for tooth 3D measurement.

  16. Self-Organization of Spatio-Temporal Hierarchy via Learning of Dynamic Visual Image Patterns on Action Sequences.

    Science.gov (United States)

    Jung, Minju; Hwang, Jungsik; Tani, Jun

    2015-01-01

    It is well known that the visual cortex efficiently processes high-dimensional spatial information by using a hierarchical structure. Recently, computational models that were inspired by the spatial hierarchy of the visual cortex have shown remarkable performance in image recognition. Up to now, however, most biological and computational modeling studies have mainly focused on the spatial domain and do not discuss temporal domain processing of the visual cortex. Several studies on the visual cortex and other brain areas associated with motor control support that the brain also uses its hierarchical structure as a processing mechanism for temporal information. Based on the success of previous computational models using spatial hierarchy and temporal hierarchy observed in the brain, the current report introduces a novel neural network model for the recognition of dynamic visual image patterns based solely on the learning of exemplars. This model is characterized by the application of both spatial and temporal constraints on local neural activities, resulting in the self-organization of a spatio-temporal hierarchy necessary for the recognition of complex dynamic visual image patterns. The evaluation with the Weizmann dataset in recognition of a set of prototypical human movement patterns showed that the proposed model is significantly robust in recognizing dynamically occluded visual patterns compared to other baseline models. Furthermore, an evaluation test for the recognition of concatenated sequences of those prototypical movement patterns indicated that the model is endowed with a remarkable capability for the contextual recognition of long-range dynamic visual image patterns.

  17. Diagnosing lung nodules on oncologic MR/PET imaging: Comparison of fast T1-weighted sequences and influence of image acquisition in inspiration and expiration breath-hold

    Energy Technology Data Exchange (ETDEWEB)

    Schwenzer, Nina F.; Seith, Ferdinand; Gatidis, Sergios; Brendle, Cornelia; Schmidt, Holger; Pfannenberg, Christina A; LaFougère, Christian; Nikolaou, Konstantin; Schraml, Christina [University Hospital of Tuebingen, Tuebingen (Germany)

    2016-09-15

    First, to investigate the diagnostic performance of fast T1-weighted sequences for lung nodule evaluation in oncologic magnetic resonance (MR)/positron emission tomography (PET). Second, to evaluate the influence of image acquisition in inspiration and expiration breath-hold on diagnostic performance. The study was approved by the local Institutional Review Board. PET/CT and MR/PET of 44 cancer patients were evaluated by 2 readers. PET/CT included lung computed tomography (CT) scans in inspiration and expiration (CTin, CTex). MR/PET included Dixon sequence for attenuation correction and fast T1-weighted volumetric interpolated breath-hold examination (VIBE) sequences (volume interpolated breath-hold examination acquired in inspiration [VIBEin], volume interpolated breath-hold examination acquired in expiration [VIBEex]). Diagnostic performance was analyzed for lesion-, lobe-, and size-dependence. Diagnostic confidence was evaluated (4-point Likert-scale; 1 = high). Jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis was performed. Seventy-six pulmonary lesions were evaluated. Lesion-based detection rates were: CTex, 77.6%; VIBEin, 53.3%; VIBEex, 51.3%; and Dixon, 22.4%. Lobe-based detection rates were: CTex, 89.6%; VIBEin, 58.3%; VIBEex, 60.4%; and Dixon, 31.3%. In contrast to CT, inspiration versus expiration did not alter diagnostic performance in VIBE sequences. Diagnostic confidence was best for VIBEin and CTex and decreased in VIBEex and Dixon (1.2 ± 0.6; 1.2 ± 0.7; 1.5 ± 0.9; 1.7 ± 1.1, respectively). The JAFROC figure-of-merit of Dixon was significantly lower. All patients with malignant lesions were identified by CTex, VIBEin, and VIBEex, while 3 patients were false-negative in Dixon. Fast T1-weighted VIBE sequences allow for identification of patients with malignant pulmonary lesions. The Dixon sequence is not recommended for lung nodule evaluation in oncologic MR/PET patients. In contrast to CT, inspiration versus

  18. Diagnosing Lung Nodules on Oncologic MR/PET Imaging: Comparison of Fast T1-Weighted Sequences and Influence of Image Acquisition in Inspiration and Expiration Breath-Hold

    Energy Technology Data Exchange (ETDEWEB)

    Schwenzer, Nina F.; Seith, Ferdinand; Gatidis, Sergios [Department of Diagnostic and Interventional Radiology, University Hospital of Tuebingen, Tuebingen 72076 (Germany); Brendle, Cornelia [Department of Diagnostic and Interventional Radiology, University Hospital of Tuebingen, Tuebingen 72076 (Germany); Department of Diagnostic and Interventional Neuroradiology, University Hospital of Tuebingen, Tuebingen 72076 (Germany); Schmidt, Holger; Pfannenberg, Christina A. [Department of Diagnostic and Interventional Radiology, University Hospital of Tuebingen, Tuebingen 72076 (Germany); Fougère, Christian la [Department of Nuclear Medicine, University Hospital of Tuebingen, Tuebingen 72076 (Germany); Nikolaou, Konstantin; Schraml, Christina [Department of Diagnostic and Interventional Radiology, University Hospital of Tuebingen, Tuebingen 72076 (Germany)

    2016-11-01

    First, to investigate the diagnostic performance of fast T1-weighted sequences for lung nodule evaluation in oncologic magnetic resonance (MR)/positron emission tomography (PET). Second, to evaluate the influence of image acquisition in inspiration and expiration breath-hold on diagnostic performance. The study was approved by the local Institutional Review Board. PET/CT and MR/PET of 44 cancer patients were evaluated by 2 readers. PET/CT included lung computed tomography (CT) scans in inspiration and expiration (CTin, CTex). MR/PET included Dixon sequence for attenuation correction and fast T1-weighted volumetric interpolated breath-hold examination (VIBE) sequences (volume interpolated breath-hold examination acquired in inspiration [VIBEin], volume interpolated breath-hold examination acquired in expiration [VIBEex]). Diagnostic performance was analyzed for lesion-, lobe-, and size-dependence. Diagnostic confidence was evaluated (4-point Likert-scale; 1 = high). Jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis was performed. Seventy-six pulmonary lesions were evaluated. Lesion-based detection rates were: CTex, 77.6%; VIBEin, 53.3%; VIBEex, 51.3%; and Dixon, 22.4%. Lobe-based detection rates were: CTex, 89.6%; VIBEin, 58.3%; VIBEex, 60.4%; and Dixon, 31.3%. In contrast to CT, inspiration versus expiration did not alter diagnostic performance in VIBE sequences. Diagnostic confidence was best for VIBEin and CTex and decreased in VIBEex and Dixon (1.2 ± 0.6; 1.2 ± 0.7; 1.5 ± 0.9; 1.7 ± 1.1, respectively). The JAFROC figure-of-merit of Dixon was significantly lower. All patients with malignant lesions were identified by CTex, VIBEin, and VIBEex, while 3 patients were false-negative in Dixon. Fast T1-weighted VIBE sequences allow for identification of patients with malignant pulmonary lesions. The Dixon sequence is not recommended for lung nodule evaluation in oncologic MR/PET patients. In contrast to CT, inspiration versus

  19. Whole-body magnetic resonance imaging for staging and follow-up of pediatric patients with Hodgkin's lymphoma: comparison of different sequences

    International Nuclear Information System (INIS)

    Nava, Daniel; Oliveira, Heverton Cesar de

    2011-01-01

    Objective: to compare the performance of the T1, T2, STIR and DWIBS (diffusion-weighted whole-body imaging with background body signal suppression) sequences in the staging and follow-up of pediatric patients with Hodgkin's lymphoma in lymph node chains, parenchymal organs and bone marrow, and to evaluate interobserver agreement. Materials and methods: the authors studied 12 patients with confirmed diagnosis of Hodgkin's lymphoma. The patients were referred for whole body magnetic resonance imaging with T1-weighted, T2-weighted, STIR and DWIBS sequences. Results: the number of lymph node sites characterized as affected by the disease on T1- and T2-weighted sequences showed similar results (8 sites for both sequences), but lower than DWIBS and STIR sequences (11 and 12 sites, respectively). The bone marrow involvement by lymphoma showed the same values for the T1-, T2-weighted and DWIBS sequences (17 lesions), higher than the value found on STIR (13 lesions). A high rate of interobserver agreement was observed as the four sequences were analyzed. Conclusion: STIR and DWIBS sequences detected the highest number of lymph node sites characterized as affected by the disease. Similar results were demonstrated by all the sequences in the evaluation of parenchymal organs and bone marrow. A high interobserver agreement was observed as the four sequences were analyzed. (author)

  20. Efficiency of Lu2SiO5:Ce (LSO) powder phosphor as X-ray to light converter under mammographic imaging conditions

    International Nuclear Information System (INIS)

    David, S.; Michail, C.; Valais, I.; Nikolopoulos, D.; Liaparinos, P.; Kalivas, N.; Kalatzis, I.; Toutountzis, A.; Efthimiou, N.; Loudos, G.; Sianoudis, I.; Cavouras, D.; Dimitropoulos, N.; Nomicos, C.D.; Kandarakis, I.; Panayiotakis, G.S.

    2007-01-01

    The aim of the present study was to examine the light emission efficiency of Lu 2 SiO 5 :Ce (LSO) powder scintillator under X-ray mammographic imaging conditions. Powder LSO scintillator has never been used in X-ray imaging. For the purposes of the present study, a 25 mg/cm 2 thick scintillating screen was prepared in our laboratory, by sedimentation of Lu 2 SiO 5 :Ce powder. Absolute luminescence efficiency measurements were performed within the range of X-ray tube voltages (22-49 kVp) used in mammographic applications. Parameters related to X-ray detection, i.e. the energy absorption efficiency (EAE) and the quantum detection efficiency (QDE) were calculated. A theoretical model, describing radiation and light transfer, was employed to fit experimental data and to estimate values of the intrinsic conversion efficiency and the light attenuation coefficients of the screen. The spectral compatibility of the LSO powder scintillator to mammographic X-ray films and to various electronic optical detectors was determined by performing light emission spectrum measurements and by taking into account the spectral sensitivity of the optical detectors. Results in the voltage range used in mammography showed that Lu 2 SiO 5 :Ce powder scintillator has approximately 10% higher values of QDE and 4.5% higher values of EAE than Gd 2 O 2 S:Tb

  1. Camera pose refinement by matching uncertain 3D building models with thermal infrared image sequences for high quality texture extraction

    Science.gov (United States)

    Iwaszczuk, Dorota; Stilla, Uwe

    2017-10-01

    Thermal infrared (TIR) images are often used to picture damaged and weak spots in the insulation of the building hull, which is widely used in thermal inspections of buildings. Such inspection in large-scale areas can be carried out by combining TIR imagery and 3D building models. This combination can be achieved via texture mapping. Automation of texture mapping avoids time consuming imaging and manually analyzing each face independently. It also provides a spatial reference for façade structures extracted in the thermal textures. In order to capture all faces, including the roofs, façades, and façades in the inner courtyard, an oblique looking camera mounted on a flying platform is used. Direct geo-referencing is usually not sufficient for precise texture extraction. In addition, 3D building models have also uncertain geometry. In this paper, therefore, methodology for co-registration of uncertain 3D building models with airborne oblique view images is presented. For this purpose, a line-based model-to-image matching is developed, in which the uncertainties of the 3D building model, as well as of the image features are considered. Matched linear features are used for the refinement of the exterior orientation parameters of the camera in order to ensure optimal co-registration. Moreover, this study investigates whether line tracking through the image sequence supports the matching. The accuracy of the extraction and the quality of the textures are assessed. For this purpose, appropriate quality measures are developed. The tests showed good results on co-registration, particularly in cases where tracking between the neighboring frames had been applied.

  2. Magnetic resonance imaging of intraoral hard and soft tissues using an intraoral coil and FLASH sequences

    Energy Technology Data Exchange (ETDEWEB)

    Fluegge, Tabea; Eisenbeiss, Anne-Kathrin; Schmelzeisen, Rainer; Nelson, Katja [University Medical Center Freiburg, Department of Oral and Maxillofacial Surgery, Freiburg (Germany); Hoevener, Jan-Bernd; Ludwig, Ute; Hennig, Juergen [University Medical Center Freiburg, Medical Physics, Department of Radiology, Freiburg (Germany); Spittau, Bjoern [Albert Ludwig University of Freiburg, Institute of Anatomy and Cell Biology, Freiburg (Germany)

    2016-12-15

    To ascertain the feasibility of MRI as a non-ionizing protocol for routine dentomaxillofacial diagnostic imaging. Wireless coils were used for MRI of intraoral hard and soft tissues. FLASH MRI was applied in vivo with a mandible voxel size of 250 x 250 x 500 μm{sup 3}, FOV of 64 x 64 x 28 mm{sup 3} and acquisition time of 3:57 min and with a maxilla voxel size of 350 μm{sup 3} and FOV of 34 cm{sup 3} in 6:40 min. Ex vivo imaging was performed in 4:38 min, with a resolution of 200 μm{sup 3} and FOV of 36.5 cm{sup 3}. Cone beam (CB) CT of the mandible and subjects were acquired. MRI was compared to CBCT and histological sections. Deviations were calculated with intraclass correlation coefficient (ICC) and coefficient of variation (c{sub v}). A high congruence between CBCT, MRI and specimens was demonstrated. Hard and soft tissues including dental pulp, periodontium, gingiva, cancellous bone and mandibular canal contents were adequately displayed with MRI. Imaging of select intraoral tissues was achieved using custom MRI protocols with an easily applicable intraoral coil in a clinically acceptable acquisition time. Comparison with CBCT and histological sections helped demonstrate dimensional accuracy of the MR images. The course of the mandibular canal was accurately displayed with CBCT and MRI. (orig.)

  3. Measurement of traffic parameters in image sequence using spatio-temporal information

    International Nuclear Information System (INIS)

    Lee, Daeho; Park, Youngtae

    2008-01-01

    This paper proposes a novel method for measurement of traffic parameters, such as the number of passed vehicles, velocity and occupancy rate, by video image analysis. The method is based on a region classification followed by spatio-temporal image analysis. Local detection region images in traffic lanes are classified into one of four categories: the road, the vehicle, the reflection and the shadow, by using statistical and structural features. Misclassification at a frame is corrected by using temporally correlated features of vehicles in the spatio-temporal image. This capability of error correction results in the accurate estimation of traffic parameters even in high traffic congestion. Also headlight detection is employed for nighttime operation. Experimental results show that the accuracy is more than 94% in our test database of diverse operating conditions such as daytime, shadowy daytime, highway, urban way, rural way, rainy day, snowy day, dusk and nighttime. The average processing time is 30 ms per frame when four traffic lanes are processed, and real-time operation could be realized while ensuring robust detection performance even for high-speed vehicles up to 150 km h −1

  4. Magnetic resonance imaging of intraoral hard and soft tissues using an intraoral coil and FLASH sequences

    International Nuclear Information System (INIS)

    Fluegge, Tabea; Eisenbeiss, Anne-Kathrin; Schmelzeisen, Rainer; Nelson, Katja; Hoevener, Jan-Bernd; Ludwig, Ute; Hennig, Juergen; Spittau, Bjoern

    2016-01-01

    To ascertain the feasibility of MRI as a non-ionizing protocol for routine dentomaxillofacial diagnostic imaging. Wireless coils were used for MRI of intraoral hard and soft tissues. FLASH MRI was applied in vivo with a mandible voxel size of 250 x 250 x 500 μm 3 , FOV of 64 x 64 x 28 mm 3 and acquisition time of 3:57 min and with a maxilla voxel size of 350 μm 3 and FOV of 34 cm 3 in 6:40 min. Ex vivo imaging was performed in 4:38 min, with a resolution of 200 μm 3 and FOV of 36.5 cm 3 . Cone beam (CB) CT of the mandible and subjects were acquired. MRI was compared to CBCT and histological sections. Deviations were calculated with intraclass correlation coefficient (ICC) and coefficient of variation (c v ). A high congruence between CBCT, MRI and specimens was demonstrated. Hard and soft tissues including dental pulp, periodontium, gingiva, cancellous bone and mandibular canal contents were adequately displayed with MRI. Imaging of select intraoral tissues was achieved using custom MRI protocols with an easily applicable intraoral coil in a clinically acceptable acquisition time. Comparison with CBCT and histological sections helped demonstrate dimensional accuracy of the MR images. The course of the mandibular canal was accurately displayed with CBCT and MRI. (orig.)

  5. Semiautomatic segmentation of aortic valve from sequenced ultrasound image using a novel shape-constraint GCV model

    International Nuclear Information System (INIS)

    Guo, Yiting; Dong, Bin; Wang, Bing; Xie, Hongzhi; Zhang, Shuyang; Gu, Lixu

    2014-01-01

    Purpose: Effective and accurate segmentation of the aortic valve (AV) from sequenced ultrasound (US) images remains a technical challenge because of intrinsic factors of ultrasound images that impact the quality and the continuous changes of shape and position of segmented objects. In this paper, a novel shape-constraint gradient Chan-Vese (GCV) model is proposed for segmenting the AV from time serial echocardiography. Methods: The GCV model is derived by incorporating the energy of the gradient vector flow into a CV model framework, where the gradient vector energy term is introduced by calculating the deviation angle between the inward normal force of the evolution contour and the gradient vector force. The flow force enlarges the capture range and enhances the blurred boundaries of objects. This is achieved by adding a circle-like contour (constructed using the AV structure region as a constraint shape) as an energy item to the GCV model through the shape comparison function. This shape-constrained energy can enhance the image constraint force by effectively connecting separate gaps of the object edge as well as driving the evolution contour to quickly approach the ideal object. Because of the slight movement of the AV in adjacent frames, the initial constraint shape is defined by users, with the other constraint shapes being derived from the segmentation results of adjacent sequence frames after morphological filtering. The AV is segmented from the US images by minimizing the proposed energy function. Results: To evaluate the performance of the proposed method, five assessment parameters were used to compare it with manual delineations performed by radiologists (gold standards). Three hundred and fifteen images acquired from nine groups were analyzed in the experiment. The area-metric overlap error rate was 6.89% ± 2.88%, the relative area difference rate 3.94% ± 2.63%, the average symmetric contour distance 1.08 ± 0.43 mm, the root mean square symmetric

  6. Fat suppression at 2D MR imaging of the hands: Dixon method versus CHESS technique and STIR sequence

    International Nuclear Information System (INIS)

    Kirchgesner, Thomas; Perlepe, Vasiliki; Michoux, Nicolas; Larbi, Ahmed; Vande Berg, Bruno

    2017-01-01

    Highlights: • Dixon yields effective fat suppression at 2D MRI of the hands. • CHESS fat suppression is less effective especially in the coronal plane. • SNR is higher with Dixon than with CHESS at T1-weighted MR imaging. • SNR is higher with CHESS than with Dixon and STIR at T2-weighted MR imaging. - Abstract: Objective: To compare the effectiveness of fat suppression and the signal-to-noise ratio (SNR) of the Dixon method with those of the CHESS (Chemical Shift-Selective) technique and STIR (Short Tau Inversion Recovery) sequence in hands of normal subjects at 2D MR imaging. Material and methods: 14 healthy volunteers (mean age of 29.4 years) consented to have both hands prospectively imaged with SE T1 Dixon, T1 CHESS, T2 Dixon, T2 CHESS and STIR sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFS BM ) and soft tissues (EFS ST ) in 20 joints per subject. One radiologist measured the SNR in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects, paired t-test and observed agreement to assess differences in effectiveness of fat suppression, differences in SNR and inter-observer agreement. Results: EFS BM was statistically significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for T2 CHESS (p < 0.0001). EFS BM was significantly higher for T2 Dixon than for STIR in the coronal plane (p = 0.0020). The SNR was significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for STIR (p < 0.0001). The SNR was significantly lower for T2 Dixon than for T2 CHESS (p < 0.0001). Conclusion: The Dixon method yields more effective fat suppression and higher SNR than the CHESS technique at 2D T1-weighted MR imaging of the hands. At T2-weighted MR imaging, fat suppression is more effective with the Dixon method while SNR is higher with the CHESS technique.

  7. Semiautomatic segmentation of aortic valve from sequenced ultrasound image using a novel shape-constraint GCV model

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yiting [Multi-disciplinary Research Center, Hebei University, Baoding 071000 (China); Dong, Bin [Hebei University Affiliated Hospital, Hebei Baoding 071000 (China); Wang, Bing [College of Mathematics and Computer Science, Hebei University, Baoding 071000 (China); Xie, Hongzhi, E-mail: xiehongzhi@medmail.com.cn, E-mail: gulixu@sjtu.edu.cn; Zhang, Shuyang [Department of Cardiovascular, Peking Union Medical College Hospital, Beijing 100005 (China); Gu, Lixu, E-mail: xiehongzhi@medmail.com.cn, E-mail: gulixu@sjtu.edu.cn [Multi-disciplinary Research Center, Hebei University, Baoding 071000, China and School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2014-07-15

    Purpose: Effective and accurate segmentation of the aortic valve (AV) from sequenced ultrasound (US) images remains a technical challenge because of intrinsic factors of ultrasound images that impact the quality and the continuous changes of shape and position of segmented objects. In this paper, a novel shape-constraint gradient Chan-Vese (GCV) model is proposed for segmenting the AV from time serial echocardiography. Methods: The GCV model is derived by incorporating the energy of the gradient vector flow into a CV model framework, where the gradient vector energy term is introduced by calculating the deviation angle between the inward normal force of the evolution contour and the gradient vector force. The flow force enlarges the capture range and enhances the blurred boundaries of objects. This is achieved by adding a circle-like contour (constructed using the AV structure region as a constraint shape) as an energy item to the GCV model through the shape comparison function. This shape-constrained energy can enhance the image constraint force by effectively connecting separate gaps of the object edge as well as driving the evolution contour to quickly approach the ideal object. Because of the slight movement of the AV in adjacent frames, the initial constraint shape is defined by users, with the other constraint shapes being derived from the segmentation results of adjacent sequence frames after morphological filtering. The AV is segmented from the US images by minimizing the proposed energy function. Results: To evaluate the performance of the proposed method, five assessment parameters were used to compare it with manual delineations performed by radiologists (gold standards). Three hundred and fifteen images acquired from nine groups were analyzed in the experiment. The area-metric overlap error rate was 6.89% ± 2.88%, the relative area difference rate 3.94% ± 2.63%, the average symmetric contour distance 1.08 ± 0.43 mm, the root mean square symmetric

  8. Fat suppression at 2D MR imaging of the hands: Dixon method versus CHESS technique and STIR sequence

    Energy Technology Data Exchange (ETDEWEB)

    Kirchgesner, Thomas, E-mail: Thomas.Kirchgesner@uclouvain.be; Perlepe, Vasiliki, E-mail: Vasiliki.Perlepe@uclouvain.be; Michoux, Nicolas, E-mail: Nicolas.Michoux@uclouvain.be; Larbi, Ahmed, E-mail: Ahmed.Larbi@chu-nimes.fr; Vande Berg, Bruno, E-mail: Bruno.VandeBerg@uclouvain.be

    2017-04-15

    Highlights: • Dixon yields effective fat suppression at 2D MRI of the hands. • CHESS fat suppression is less effective especially in the coronal plane. • SNR is higher with Dixon than with CHESS at T1-weighted MR imaging. • SNR is higher with CHESS than with Dixon and STIR at T2-weighted MR imaging. - Abstract: Objective: To compare the effectiveness of fat suppression and the signal-to-noise ratio (SNR) of the Dixon method with those of the CHESS (Chemical Shift-Selective) technique and STIR (Short Tau Inversion Recovery) sequence in hands of normal subjects at 2D MR imaging. Material and methods: 14 healthy volunteers (mean age of 29.4 years) consented to have both hands prospectively imaged with SE T1 Dixon, T1 CHESS, T2 Dixon, T2 CHESS and STIR sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFS{sup BM}) and soft tissues (EFS{sup ST}) in 20 joints per subject. One radiologist measured the SNR in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects, paired t-test and observed agreement to assess differences in effectiveness of fat suppression, differences in SNR and inter-observer agreement. Results: EFS{sup BM} was statistically significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for T2 CHESS (p < 0.0001). EFS{sup BM} was significantly higher for T2 Dixon than for STIR in the coronal plane (p = 0.0020). The SNR was significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for STIR (p < 0.0001). The SNR was significantly lower for T2 Dixon than for T2 CHESS (p < 0.0001). Conclusion: The Dixon method yields more effective fat suppression and higher SNR than the CHESS technique at 2D T1-weighted MR imaging of the hands. At T2-weighted MR imaging, fat suppression is more effective with the Dixon method while SNR is higher with the CHESS technique.

  9. Fully automatic registration and segmentation of first-pass myocardial perfusion MR image sequences.

    Science.gov (United States)

    Gupta, Vikas; Hendriks, Emile A; Milles, Julien; van der Geest, Rob J; Jerosch-Herold, Michael; Reiber, Johan H C; Lelieveldt, Boudewijn P F

    2010-11-01

    Derivation of diagnostically relevant parameters from first-pass myocardial perfusion magnetic resonance images involves the tedious and time-consuming manual segmentation of the myocardium in a large number of images. To reduce the manual interaction and expedite the perfusion analysis, we propose an automatic registration and segmentation method for the derivation of perfusion linked parameters. A complete automation was accomplished by first registering misaligned images using a method based on independent component analysis, and then using the registered data to automatically segment the myocardium with active appearance models. We used 18 perfusion studies (100 images per study) for validation in which the automatically obtained (AO) contours were compared with expert drawn contours on the basis of point-to-curve error, Dice index, and relative perfusion upslope in the myocardium. Visual inspection revealed successful segmentation in 15 out of 18 studies. Comparison of the AO contours with expert drawn contours yielded 2.23 ± 0.53 mm and 0.91 ± 0.02 as point-to-curve error and Dice index, respectively. The average difference between manually and automatically obtained relative upslope parameters was found to be statistically insignificant (P = .37). Moreover, the analysis time per slice was reduced from 20 minutes (manual) to 1.5 minutes (automatic). We proposed an automatic method that significantly reduced the time required for analysis of first-pass cardiac magnetic resonance perfusion images. The robustness and accuracy of the proposed method were demonstrated by the high spatial correspondence and statistically insignificant difference in perfusion parameters, when AO contours were compared with expert drawn contours. Copyright © 2010 AUR. Published by Elsevier Inc. All rights reserved.

  10. Fat-Suppressed T2 Sequences for Routine 3.0-Tesla Lumbar Spine Magnetic Resonance Imaging: A Preliminary Report

    Energy Technology Data Exchange (ETDEWEB)

    McKinney, A. M.; Gadani, S.; Palmer, C. S.; Vidarsson, L. (Dept. of Radiology, Hennepin County and Univ. of Minnesota Medical Centers, Minneapolis, MN (United States))

    2008-09-15

    Background: Clear depiction of the ligamentum flavum on routine lumbar magnetic resonance imaging (MRI) is essential in accurately describing the extent of degenerative disease. In routine, noncontrast evaluations, focal fatty deposition or hemangiomas can be difficult to distinguish from malignant foci on fast spin-echo (FSE) T2-weighted images. Purpose: To describe the use of T2 fast field echo (T2FFE) in combination with spectral presaturation inversion recovery (SPIR) fat suppression for noncontrast, routine lumbar spine outpatient MR imaging at 3.0 Tesla (3T). Material and Methods: An axial gradient echo (GE) T2FFE sequence was combined with SPIR fat suppression (T2FFE-SPIR), via a 3T Philips Intera (Philips Medical Systems, Best, The Netherlands) scanner, and added to the routine, noncontrast lumbar MRI examinations, which included sagittal FSE T1-weighted (T1WI), T2-weighted (T2WI), short-tau inversion recovery (STIR), and axial FSE T2WI. The sequence was performed in over 500 patients over a 1-year period, without intravenous contrast, and with slice thickness and planes of section identical to the axial FSE T1WI and T2WI images. The sequence typically lasted about 4.5-6 min. Results: The use of T2FFE-SPIR enabled visualization of the ligamentum flavum in degenerative disease, and the exclusion of focal fatty lesions on FSE T2WI. Other benefits included: the identification of malignant foci, the uncommon detection of hemorrhage, and the elimination of spurious flow voids. Several brief examples are provided to demonstrate the utility of this technique. Conclusion: The addition of T2FFE-SPIR to routine, noncontrast protocols in outpatients could provide further confidence in the visualization of the ligamentum flavum in degenerative disease, and can exclude malignancy in T2-bright areas of focal fatty marrow. Larger studies would be helpful to evaluate the accuracy of this technique versus FSE techniques in depicting degenerative, malignant, or inflammatory

  11. Fat-Suppressed T2* Sequences for Routine 3.0-Tesla Lumbar Spine Magnetic Resonance Imaging: A Preliminary Report

    International Nuclear Information System (INIS)

    McKinney, A. M.; Gadani, S.; Palmer, C. S.; Vidarsson, L.

    2008-01-01

    Background: Clear depiction of the ligamentum flavum on routine lumbar magnetic resonance imaging (MRI) is essential in accurately describing the extent of degenerative disease. In routine, noncontrast evaluations, focal fatty deposition or hemangiomas can be difficult to distinguish from malignant foci on fast spin-echo (FSE) T2-weighted images. Purpose: To describe the use of T2* fast field echo (T2FFE) in combination with spectral presaturation inversion recovery (SPIR) fat suppression for noncontrast, routine lumbar spine outpatient MR imaging at 3.0 Tesla (3T). Material and Methods: An axial gradient echo (GE) T2FFE sequence was combined with SPIR fat suppression (T2FFE-SPIR), via a 3T Philips Intera (Philips Medical Systems, Best, The Netherlands) scanner, and added to the routine, noncontrast lumbar MRI examinations, which included sagittal FSE T1-weighted (T1WI), T2-weighted (T2WI), short-tau inversion recovery (STIR), and axial FSE T2WI. The sequence was performed in over 500 patients over a 1-year period, without intravenous contrast, and with slice thickness and planes of section identical to the axial FSE T1WI and T2WI images. The sequence typically lasted about 4.5-6 min. Results: The use of T2FFE-SPIR enabled visualization of the ligamentum flavum in degenerative disease, and the exclusion of focal fatty lesions on FSE T2WI. Other benefits included: the identification of malignant foci, the uncommon detection of hemorrhage, and the elimination of spurious flow voids. Several brief examples are provided to demonstrate the utility of this technique. Conclusion: The addition of T2FFE-SPIR to routine, noncontrast protocols in outpatients could provide further confidence in the visualization of the ligamentum flavum in degenerative disease, and can exclude malignancy in T2-bright areas of focal fatty marrow. Larger studies would be helpful to evaluate the accuracy of this technique versus FSE techniques in depicting degenerative, malignant, or inflammatory

  12. Prognostic value of gradient echo T2* sequences for brain MR imaging in preterm infants

    International Nuclear Information System (INIS)

    Bruine, Francisca T. de; Berg-Huysmans, Annette A. van den; Buchem, Mark A. van; Grond, Jeroen van der; Steggerda, Sylke J.; Leijser, Lara M.; Rijken, Monique; Wezel-Meijler, Gerda van

    2014-01-01

    Gradient echo T2*-W sequences are more sensitive than T2-W spin-echo sequences for detecting hemorrhages in the brain. The aim of this study is to correlate presence of hemosiderin deposits in the brain of very preterm infants (gestational age 6 non-hemorrhagic punctate white matter lesions (PWML), cysts and/or ventricular dilatation. Six infants with post-hemorrhagic ventricular dilatation detected by US in the neonatal period were excluded. Infants were seen for follow-up at 2 years. Univariate and regression analysis assessed the relation between presence and location of hemosiderin, white matter injury and neurodevelopmental outcome. In 38/95 (40%) of the infants, hemosiderin was detected. Twenty percent (19/95) of the infants were lost to follow-up. There was a correlation between hemosiderin in the ventricular wall with >6 PWML (P < 0.001) and cysts (P < 0.001) at term-equivalent age, and with a lower psychomotor development index (PDI) (P=0.02) at 2 years. After correcting for known confounders (gestational age, gender, intrauterine growth retardation and white matter injury), the correlation with PDI was no longer significant. The clinical importance of detecting small hemosiderin deposits is limited as there is no independent association with neurodevelopmental outcome. (orig.)

  13. Micro-motion Recognition of Spatial Cone Target Based on ISAR Image Sequences

    Directory of Open Access Journals (Sweden)

    Changyong Shu

    2016-04-01

    Full Text Available The accurate micro-motions recognition of spatial cone target is the foundation of the characteristic parameter acquisition. For this reason, a micro-motion recognition method based on the distinguishing characteristics extracted from the Inverse Synthetic Aperture Radar (ISAR sequences is proposed in this paper. The projection trajectory formula of cone node strong scattering source and cone bottom slip-type strong scattering sources, which are located on the spatial cone target, are deduced under three micro-motion types including nutation, precession, and spinning, and the correctness is verified by the electromagnetic simulation. By comparison, differences are found among the projection of the scattering sources with different micro-motions, the coordinate information of the scattering sources in the Inverse Synthetic Aperture Radar sequences is extracted by the CLEAN algorithm, and the spinning is recognized by setting the threshold value of Doppler. The double observation points Interacting Multiple Model Kalman Filter is used to separate the scattering sources projection of the nutation target or precession target, and the cross point number of each scattering source’s projection track is used to classify the nutation or precession. Finally, the electromagnetic simulation data are used to verify the effectiveness of the micro-motion recognition method.

  14. Non-parametric Bayesian models of response function in dynamic image sequences

    Czech Academy of Sciences Publication Activity Database

    Tichý, Ondřej; Šmídl, Václav

    2016-01-01

    Roč. 151, č. 1 (2016), s. 90-100 ISSN 1077-3142 R&D Projects: GA ČR GA13-29225S Institutional support: RVO:67985556 Keywords : Response function * Blind source separation * Dynamic medical imaging * Probabilistic models * Bayesian methods Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 2.498, year: 2016 http://library.utia.cas.cz/separaty/2016/AS/tichy-0456983.pdf

  15. Bayesian Blind Separation and Deconvolution of Dynamic Image Sequences Using Sparsity Priors

    Czech Academy of Sciences Publication Activity Database

    Tichý, Ondřej; Šmídl, Václav

    2015-01-01

    Roč. 34, č. 1 (2015), s. 258-266 ISSN 0278-0062 R&D Projects: GA ČR GA13-29225S Keywords : Functional imaging * Blind source separation * Computer-aided detection and diagnosis * Probabilistic and statistical methods Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 3.756, year: 2015 http://library.utia.cas.cz/separaty/2014/AS/tichy-0431090.pdf

  16. MR diffusion weighted imaging of gastric cancer: b-value determination and comparison with routine sequences

    International Nuclear Information System (INIS)

    Zhao Xiaopeng; Tang Lei; Sun Yingshi; Li Jie; Cao Kun

    2007-01-01

    Objective: To choose the optimal b-values for the DWI of gastric cancer (GC), and investigate the value of DWI in the diagnosis of GCs. Methods: MRI examinations (T 1 WI, T 2 WI, and DWI) were performed on 31 patients with gastric cancer. Three diffusion-weighted sequences were designed with different b values, including 300 s/mm 2 (low), 600 s/mm 2 (intermediate), and 1000 s/mm 2 (high). Free water grade was used to evaluate the suppression of content in gastric lumen. Background contrast grade was used to evaluate the discriminating ability of different sequences between GC and nearby tissues. The ADCs of GCs, nearby gastric wall region, and free water in gastric lumen were measured. SNR Ca , CNR Ca-GW and SIR CaGW of high b-value DWI and routine MRI sequences were evaluated and compared. Results: The signal intensity of free water in gastric lumen decreased as b-value increased, and the SIR were 8.11± 0.77 (b=300 s/mm 2 ), 2.70±0.35 (b=600 s/mm 2 ), and 1.13±0.22 (b=1000 s/mm 2 ) (F55.368, P 2 =16.692, P 2 =9.923, P -3 mm 2 /s, (1.43±0.41) x 10 -3 mm 2 /s, and (1.18±0.25) x 10 -3 mm 2 /s; (F=12.066, P 1 WI (CNR: 12.46 vs. 2.35, Z=-3.746, P 2 WI (CNR: 12.46 vs. 3.92, Z=-3.518, P 2 ) is reasonable for DWI of GCs, which can reflect diffusion condition of water molecules more accurately, suppress signal of content in gastric lumen, and possess higher contrast. DWI can be a supplementary method of routine MRI examination for better demonstration of gastric cancers. (authors)

  17. MCTP system model based on linear programming optimization of apertures obtained from sequencing patient image data maps

    Energy Technology Data Exchange (ETDEWEB)

    Ureba, A. [Dpto. Fisiología Médica y Biofísica. Facultad de Medicina, Universidad de Sevilla, E-41009 Sevilla (Spain); Salguero, F. J. [Nederlands Kanker Instituut, Antoni van Leeuwenhoek Ziekenhuis, 1066 CX Ámsterdam, The Nederlands (Netherlands); Barbeiro, A. R.; Jimenez-Ortega, E.; Baeza, J. A.; Leal, A., E-mail: alplaza@us.es [Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, E-41009 Sevilla (Spain); Miras, H. [Servicio de Radiofísica, Hospital Universitario Virgen Macarena, E-41009 Sevilla (Spain); Linares, R.; Perucha, M. [Servicio de Radiofísica, Hospital Infanta Luisa, E-41010 Sevilla (Spain)

    2014-08-15

    Purpose: The authors present a hybrid direct multileaf collimator (MLC) aperture optimization model exclusively based on sequencing of patient imaging data to be implemented on a Monte Carlo treatment planning system (MC-TPS) to allow the explicit radiation transport simulation of advanced radiotherapy treatments with optimal results in efficient times for clinical practice. Methods: The planning system (called CARMEN) is a full MC-TPS, controlled through aMATLAB interface, which is based on the sequencing of a novel map, called “biophysical” map, which is generated from enhanced image data of patients to achieve a set of segments actually deliverable. In order to reduce the required computation time, the conventional fluence map has been replaced by the biophysical map which is sequenced to provide direct apertures that will later be weighted by means of an optimization algorithm based on linear programming. A ray-casting algorithm throughout the patient CT assembles information about the found structures, the mass thickness crossed, as well as PET values. Data are recorded to generate a biophysical map for each gantry angle. These maps are the input files for a home-made sequencer developed to take into account the interactions of photons and electrons with the MLC. For each linac (Axesse of Elekta and Primus of Siemens) and energy beam studied (6, 9, 12, 15 MeV and 6 MV), phase space files were simulated with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code. This code is a modified version of EGSnrc/DOSXYZnrc able to calculate the beamlet dose in order to combine them with different weights during the optimization process. Results: Three complex radiotherapy treatments were selected to check the reliability of CARMEN in situations where the MC calculation can offer an added value: A head-and-neck case (Case I) with three targets delineated on PET/CT images and a demanding dose-escalation; a partial breast

  18. MCTP system model based on linear programming optimization of apertures obtained from sequencing patient image data maps

    International Nuclear Information System (INIS)

    Ureba, A.; Salguero, F. J.; Barbeiro, A. R.; Jimenez-Ortega, E.; Baeza, J. A.; Leal, A.; Miras, H.; Linares, R.; Perucha, M.

    2014-01-01

    Purpose: The authors present a hybrid direct multileaf collimator (MLC) aperture optimization model exclusively based on sequencing of patient imaging data to be implemented on a Monte Carlo treatment planning system (MC-TPS) to allow the explicit radiation transport simulation of advanced radiotherapy treatments with optimal results in efficient times for clinical practice. Methods: The planning system (called CARMEN) is a full MC-TPS, controlled through aMATLAB interface, which is based on the sequencing of a novel map, called “biophysical” map, which is generated from enhanced image data of patients to achieve a set of segments actually deliverable. In order to reduce the required computation time, the conventional fluence map has been replaced by the biophysical map which is sequenced to provide direct apertures that will later be weighted by means of an optimization algorithm based on linear programming. A ray-casting algorithm throughout the patient CT assembles information about the found structures, the mass thickness crossed, as well as PET values. Data are recorded to generate a biophysical map for each gantry angle. These maps are the input files for a home-made sequencer developed to take into account the interactions of photons and electrons with the MLC. For each linac (Axesse of Elekta and Primus of Siemens) and energy beam studied (6, 9, 12, 15 MeV and 6 MV), phase space files were simulated with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code. This code is a modified version of EGSnrc/DOSXYZnrc able to calculate the beamlet dose in order to combine them with different weights during the optimization process. Results: Three complex radiotherapy treatments were selected to check the reliability of CARMEN in situations where the MC calculation can offer an added value: A head-and-neck case (Case I) with three targets delineated on PET/CT images and a demanding dose-escalation; a partial breast

  19. MCTP system model based on linear programming optimization of apertures obtained from sequencing patient image data maps.

    Science.gov (United States)

    Ureba, A; Salguero, F J; Barbeiro, A R; Jimenez-Ortega, E; Baeza, J A; Miras, H; Linares, R; Perucha, M; Leal, A

    2014-08-01

    The authors present a hybrid direct multileaf collimator (MLC) aperture optimization model exclusively based on sequencing of patient imaging data to be implemented on a Monte Carlo treatment planning system (MC-TPS) to allow the explicit radiation transport simulation of advanced radiotherapy treatments with optimal results in efficient times for clinical practice. The planning system (called CARMEN) is a full MC-TPS, controlled through aMATLAB interface, which is based on the sequencing of a novel map, called "biophysical" map, which is generated from enhanced image data of patients to achieve a set of segments actually deliverable. In order to reduce the required computation time, the conventional fluence map has been replaced by the biophysical map which is sequenced to provide direct apertures that will later be weighted by means of an optimization algorithm based on linear programming. A ray-casting algorithm throughout the patient CT assembles information about the found structures, the mass thickness crossed, as well as PET values. Data are recorded to generate a biophysical map for each gantry angle. These maps are the input files for a home-made sequencer developed to take into account the interactions of photons and electrons with the MLC. For each linac (Axesse of Elekta and Primus of Siemens) and energy beam studied (6, 9, 12, 15 MeV and 6 MV), phase space files were simulated with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code. This code is a modified version of EGSnrc/DOSXYZnrc able to calculate the beamlet dose in order to combine them with different weights during the optimization process. Three complex radiotherapy treatments were selected to check the reliability of CARMEN in situations where the MC calculation can offer an added value: A head-and-neck case (Case I) with three targets delineated on PET/CT images and a demanding dose-escalation; a partial breast irradiation case (Case II) solved

  20. General method for labeling siRNA by click chemistry with fluorine-18 for the purpose of PET imaging.

    Science.gov (United States)

    Mercier, Frédéric; Paris, Jérôme; Kaisin, Geoffroy; Thonon, David; Flagothier, Jessica; Teller, Nathalie; Lemaire, Christian; Luxen, André

    2011-01-19

    The alkyne-azide Cu(I)-catalyzed Huisgen cycloaddition, a click-type reaction, was used to label a double-stranded oligonucleotide (siRNA) with fluorine-18. An alkyne solid support CPG for the preparation of monostranded oligonucleotides functionalized with alkyne has been developed. Two complementary azide labeling agents (1-(azidomethyl)-4-[(18)F]fluorobenzene) and 1-azido-4-(3-[(18)F]fluoropropoxy)benzene have been produced with 41% and 35% radiochemical yields (decay-corrected), respectively. After annealing with the complementary strand, the siRNA was directly labeled by click chemistry with [(18)F]fluoroazide to produce the [(18)F]-radiolabeled siRNA with excellent radiochemical yield and purity.

  1. Optimization of parameter values for complex pulse sequences by simulated annealing: application to 3D MP-RAGE imaging of the brain.

    Science.gov (United States)

    Epstein, F H; Mugler, J P; Brookeman, J R

    1994-02-01

    A number of pulse sequence techniques, including magnetization-prepared gradient echo (MP-GRE), segmented GRE, and hybrid RARE, employ a relatively large number of variable pulse sequence parameters and acquire the image data during a transient signal evolution. These sequences have recently been proposed and/or used for clinical applications in the brain, spine, liver, and coronary arteries. Thus, the need for a method of deriving optimal pulse sequence parameter values for this class of sequences now exists. Due to the complexity of these sequences, conventional optimization approaches, such as applying differential calculus to signal difference equations, are inadequate. We have developed a general framework for adapting the simulated annealing algorithm to pulse sequence parameter value optimization, and applied this framework to the specific case of optimizing the white matter-gray matter signal difference for a T1-weighted variable flip angle 3D MP-RAGE sequence. Using our algorithm, the values of 35 sequence parameters, including the magnetization-preparation RF pulse flip angle and delay time, 32 flip angles in the variable flip angle gradient-echo acquisition sequence, and the magnetization recovery time, were derived. Optimized 3D MP-RAGE achieved up to a 130% increase in white matter-gray matter signal difference compared with optimized 3D RF-spoiled FLASH with the same total acquisition time. The simulated annealing approach was effective at deriving optimal parameter values for a specific 3D MP-RAGE imaging objective, and may be useful for other imaging objectives and sequences in this general class.

  2. Real-time 3D reconstruction of road curvature in far look-ahead distance from analysis of image sequences

    Science.gov (United States)

    Behringer, Reinhold

    1995-12-01

    A system for visual road recognition in far look-ahead distance, implemented in the autonomous road vehicle VaMP (a passenger car), is described. Visual cues of a road in a video image are the bright lane markings and the edges formed at the road borders. In a distance of more than 100 m, the most relevant road cue is the homogeneous road area, limited by the two border edges. These cues can be detected by the image processing module KRONOS applying edge detection techniques and areal 2D segmentation based on resolution triangles (analogous to a resolution pyramid). An estimation process performs an update of a state vector, which describes spatial road shape and vehicle orientation relative to the road. This state vector is estimated every 40 ms by exploiting knowledge about the vehicle movement (spatio-temporal model of vehicle dynamics) and the road design rules (clothoidal segments). Kalman filter techniques are applied to obtain an optimal estimate of the state vector by evaluating the measurements of the road border positions in the image sequence taken by a set of CCD cameras. The road consists of segments with piecewise constant curvature parameters. The borders between these segments can be detected by applying methods which have been developed for detection of discontinuities during time-discrete measurements. The road recognition system has been tested in autonomous rides with VaMP on public Autobahnen in real traffic at speeds up to 130 km/h.

  3. Prognostic value of gradient echo T2* sequences for brain MR imaging in preterm infants

    Energy Technology Data Exchange (ETDEWEB)

    Bruine, Francisca T. de; Berg-Huysmans, Annette A. van den; Buchem, Mark A. van; Grond, Jeroen van der [Leiden University Medical Center, Department of Radiology, PO Box 9600, Leiden (Netherlands); Steggerda, Sylke J.; Leijser, Lara M.; Rijken, Monique [Leiden University Medical Center, Department of Pediatrics, subdivision of Neonatology, Leiden (Netherlands); Wezel-Meijler, Gerda van [Leiden University Medical Center, Department of Pediatrics, subdivision of Neonatology, Leiden (Netherlands); Isala Hospital, Department of Neonatology, Zwolle (Netherlands)

    2014-03-15

    Gradient echo T2*-W sequences are more sensitive than T2-W spin-echo sequences for detecting hemorrhages in the brain. The aim of this study is to correlate presence of hemosiderin deposits in the brain of very preterm infants (gestational age <32 weeks) detected by T2*-W gradient echo MRI to white matter injury and neurodevelopmental outcome at 2 years. In 101 preterm infants, presence and location of hemosiderin were assessed on T2*-W gradient echo MRI performed around term-equivalent age (range: 40-60 weeks). White matter injury was defined as the presence of >6 non-hemorrhagic punctate white matter lesions (PWML), cysts and/or ventricular dilatation. Six infants with post-hemorrhagic ventricular dilatation detected by US in the neonatal period were excluded. Infants were seen for follow-up at 2 years. Univariate and regression analysis assessed the relation between presence and location of hemosiderin, white matter injury and neurodevelopmental outcome. In 38/95 (40%) of the infants, hemosiderin was detected. Twenty percent (19/95) of the infants were lost to follow-up. There was a correlation between hemosiderin in the ventricular wall with >6 PWML (P < 0.001) and cysts (P < 0.001) at term-equivalent age, and with a lower psychomotor development index (PDI) (P=0.02) at 2 years. After correcting for known confounders (gestational age, gender, intrauterine growth retardation and white matter injury), the correlation with PDI was no longer significant. The clinical importance of detecting small hemosiderin deposits is limited as there is no independent association with neurodevelopmental outcome. (orig.)

  4. The 2012 Emilia seismic sequence (Northern Italy): Imaging the thrust fault system by accurate aftershock location

    Science.gov (United States)

    Govoni, Aladino; Marchetti, Alessandro; De Gori, Pasquale; Di Bona, Massimo; Lucente, Francesco Pio; Improta, Luigi; Chiarabba, Claudio; Nardi, Anna; Margheriti, Lucia; Agostinetti, Nicola Piana; Di Giovambattista, Rita; Latorre, Diana; Anselmi, Mario; Ciaccio, Maria Grazia; Moretti, Milena; Castellano, Corrado; Piccinini, Davide

    2014-05-01

    Starting from late May 2012, the Emilia region (Northern Italy) was severely shaken by an intense seismic sequence, originated from a ML 5.9 earthquake on May 20th, at a hypocentral depth of 6.3 km, with thrust-type focal mechanism. In the following days, the seismic rate remained high, counting 50 ML ≥ 2.0 earthquakes a day, on average. Seismicity spreads along a 30 km east-west elongated area, in the Po river alluvial plain, in the nearby of the cities Ferrara and Modena. Nine days after the first shock, another destructive thrust-type earthquake (ML 5.8) hit the area to the west, causing further damage and fatalities. Aftershocks following this second destructive event extended along the same east-westerly trend for further 20 km to the west, thus illuminating an area of about 50 km in length, on the whole. After the first shock struck, on May 20th, a dense network of temporary seismic stations, in addition to the permanent ones, was deployed in the meizoseismal area, leading to a sensible improvement of the earthquake monitoring capability there. A combined dataset, including three-component seismic waveforms recorded by both permanent and temporary stations, has been analyzed in order to obtain an appropriate 1-D velocity model for earthquake location in the study area. Here we describe the main seismological characteristics of this seismic sequence and, relying on refined earthquakes location, we make inferences on the geometry of the thrust system responsible for the two strongest shocks.

  5. An image encryption scheme based on the MLNCML system using DNA sequences

    Science.gov (United States)

    Zhang, Ying-Qian; Wang, Xing-Yuan; Liu, Jia; Chi, Ze-Lin

    2016-07-01

    We propose a new image scheme based on the spatiotemporal chaos of the Mixed Linear-Nonlinear Coupled Map Lattices (MLNCML). This spatiotemporal chaotic system has more cryptographic features in dynamics than the system of Coupled Map Lattices (CML). In the proposed scheme, we employ the strategy of DNA computing and one time pad encryption policy, which can enhance the sensitivity to the plaintext and resist differential attack, brute-force attack, statistical attack and plaintext attack. Simulation results and theoretical analysis indicate that the proposed scheme has superior high security.

  6. MR imaging of the knee: Improvement of signal and contrast efficiency of T1-weighted turbo spin echo sequences by applying a driven equilibrium (DRIVE) pulse

    Energy Technology Data Exchange (ETDEWEB)

    Radlbauer, Rudolf, E-mail: rudolf.radlbauer@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Lomoschitz, Friedrich, E-mail: friedrich.lomoschitz@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Salomonowitz, Erich, E-mail: erich.salomonowitz@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Eberhardt, Knut E., E-mail: info@mrt-kompetenzzentrum.d [MRT Competence Center Schloss Werneck, Balthasar-Neumann-Platz 2, 97440 Werneck (Germany); Stadlbauer, Andreas, E-mail: andi@nmr.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen (Germany)

    2010-08-15

    The purpose of this study was to assess the effect of a driven equilibrium (DRIVE) pulse incorporated in a standard T1-weighted turbo spin echo (TSE) sequence as used in our routine MRI protocol for examination of pathologies of the knee. Sixteen consecutive patients with knee disorders were examined using the routine MRI protocol, including T1-weighted TSE-sequences with and without a DRIVE pulse. Signal-to-noise ratios (SNRs) and contrast-to-noise ratio (CNR) of anatomical structures and pathologies were calculated and compared for both sequences. The differences in diagnostic value of the T1-weighted images with and without DRIVE pulse were assessed. SNR was significantly higher on images acquired with DRIVE pulse for fluid, effusion, cartilage and bone. Differences in the SNR of meniscus and muscle between the two sequences were not statistically significant. CNR was significantly increased between muscle and effusion, fluid and cartilage, fluid and meniscus, cartilage and meniscus, bone and cartilage on images acquired using the DRIVE pulse. Diagnostic value of the T1-weighted images was found to be improved for delineation of anatomic structures and for diagnosing a variety of pathologies when a DRIVE pulse is incorporated in the sequence. Incorporation of a DRIVE pulse into a standard T1-weighted TSE-sequence leads to significant increase of SNR and CNR of both, anatomical structures and pathologies, and consequently to an increase in diagnostic value within the same acquisition time.

  7. MR imaging of the knee: Improvement of signal and contrast efficiency of T1-weighted turbo spin echo sequences by applying a driven equilibrium (DRIVE) pulse

    International Nuclear Information System (INIS)

    Radlbauer, Rudolf; Lomoschitz, Friedrich; Salomonowitz, Erich; Eberhardt, Knut E.; Stadlbauer, Andreas

    2010-01-01

    The purpose of this study was to assess the effect of a driven equilibrium (DRIVE) pulse incorporated in a standard T1-weighted turbo spin echo (TSE) sequence as used in our routine MRI protocol for examination of pathologies of the knee. Sixteen consecutive patients with knee disorders were examined using the routine MRI protocol, including T1-weighted TSE-sequences with and without a DRIVE pulse. Signal-to-noise ratios (SNRs) and contrast-to-noise ratio (CNR) of anatomical structures and pathologies were calculated and compared for both sequences. The differences in diagnostic value of the T1-weighted images with and without DRIVE pulse were assessed. SNR was significantly higher on images acquired with DRIVE pulse for fluid, effusion, cartilage and bone. Differences in the SNR of meniscus and muscle between the two sequences were not statistically significant. CNR was significantly increased between muscle and effusion, fluid and cartilage, fluid and meniscus, cartilage and meniscus, bone and cartilage on images acquired using the DRIVE pulse. Diagnostic value of the T1-weighted images was found to be improved for delineation of anatomic structures and for diagnosing a variety of pathologies when a DRIVE pulse is incorporated in the sequence. Incorporation of a DRIVE pulse into a standard T1-weighted TSE-sequence leads to significant increase of SNR and CNR of both, anatomical structures and pathologies, and consequently to an increase in diagnostic value within the same acquisition time.

  8. Gadobenate dimeglumine-enhanced MR of VX2 carcinoma in rabbit liver: usefulness of the delayed phase imaging and optimal pulse sequence

    International Nuclear Information System (INIS)

    Cho, Seung Il; Lee, Jeong Min; Kim, Young Kon; Kim, Chong Soo

    2002-01-01

    To assess the diagnostic value of delayed imaging using gadobenate dimeglumine (MultiHance) and to determine the optimal pulse sequence for the detection of VX2 carcinoma lesions in the rabbit. Twelve VX2 carcinomas implanted in the livers of eleven New Zealand rabbits were studied. All patients underwent an MR protocal consisting of precontrast T2-and T1-weighted sequences, followed by repetition of the T1-weighted sequence at 0 to 30 (arterial phase). 31-60 (portal phase), and 40 minutes (delayed phase) after the intravenous administration of 0.1 mmol/kg of gadobenate dimeglumine. The signal-to-noise ratio (SNR) of the liver and VX2 tumor, and the lesion-to-liver contrast-to-noise ratio (CNR) of precontrast and postcontrast MR images were quantitatively analyzed, and two experienced radiologists evaluated image quality in terms of lesion conspicuity, artifact, mass delineation, and vascular anatomy. Liver SNR was significantly higher at delayed imaging than at precontrast, arterial, and portal imaging (p<0.05), while lesion SNR was significantly higher at delayed imaging than at precontrast imaging (p<0.05). Lesion CNR was higher at delayed imaging than at precontrast and portal phase imaging (p<0.05), but there was no difference between arterial and delayed imaging. The latter provided better mass delineation than precontrast, arterial and portal phase imaging (p<0.05). While in terms of lesion conspicuity and vascular anatomy, the delayed phase was better than the arterial phase (p<0.05) but similar to the precontrast and portal phase. During the delayed phase, the gradient-echo sequence showed better results than the spin-echo in terms of liver SNR, and lesion SNR and CNR (p<0.05). Because it provides better lesion conspicuity and mass delineation by improving liver SNR and lesion-to-liver CNR, the addition of the delayed phase to a dynamic MRI sequence after gadobenate dimeglumine adminstration facilitates lesion detection. For delayed-phase imaging, the

  9. Gadobenate dimeglumine-enhanced MR of VX2 carcinoma in rabbit liver: usefulness of the delayed phase imaging and optimal pulse sequence

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seung Il; Lee, Jeong Min; Kim, Young Kon; Kim, Chong Soo [College of Medicine, Chonbuk National Univ., Chonju (Korea, Republic of)

    2002-07-01

    To assess the diagnostic value of delayed imaging using gadobenate dimeglumine (MultiHance) and to determine the optimal pulse sequence for the detection of VX2 carcinoma lesions in the rabbit. Twelve VX2 carcinomas implanted in the livers of eleven New Zealand rabbits were studied. All patients underwent an MR protocal consisting of precontrast T2-and T1-weighted sequences, followed by repetition of the T1-weighted sequence at 0 to 30 (arterial phase). 31-60 (portal phase), and 40 minutes (delayed phase) after the intravenous administration of 0.1 mmol/kg of gadobenate dimeglumine. The signal-to-noise ratio (SNR) of the liver and VX2 tumor, and the lesion-to-liver contrast-to-noise ratio (CNR) of precontrast and postcontrast MR images were quantitatively analyzed, and two experienced radiologists evaluated image quality in terms of lesion conspicuity, artifact, mass delineation, and vascular anatomy. Liver SNR was significantly higher at delayed imaging than at precontrast, arterial, and portal imaging (p<0.05), while lesion SNR was significantly higher at delayed imaging than at precontrast imaging (p<0.05). Lesion CNR was higher at delayed imaging than at precontrast and portal phase imaging (p<0.05), but there was no difference between arterial and delayed imaging. The latter provided better mass delineation than precontrast, arterial and portal phase imaging (p<0.05). While in terms of lesion conspicuity and vascular anatomy, the delayed phase was better than the arterial phase (p<0.05) but similar to the precontrast and portal phase. During the delayed phase, the gradient-echo sequence showed better results than the spin-echo in terms of liver SNR, and lesion SNR and CNR (p<0.05). Because it provides better lesion conspicuity and mass delineation by improving liver SNR and lesion-to-liver CNR, the addition of the delayed phase to a dynamic MRI sequence after gadobenate dimeglumine adminstration facilitates lesion detection. For delayed-phase imaging, the

  10. Imaging Josephson vortices on the surface superconductor Si(111)-(√7×√3)-In using a scanning tunneling microscope.

    Science.gov (United States)

    Yoshizawa, Shunsuke; Kim, Howon; Kawakami, Takuto; Nagai, Yuki; Nakayama, Tomonobu; Hu, Xiao; Hasegawa, Yukio; Uchihashi, Takashi

    2014-12-12

    We have studied the superconducting Si(111)-(√7×√3)-In surface using a ³He-based low-temperature scanning tunneling microscope. Zero-bias conductance images taken over a large surface area reveal that vortices are trapped at atomic steps after magnetic fields are applied. The crossover behavior from Pearl to Josephson vortices is clearly identified from their elongated shapes along the steps and significant recovery of superconductivity within the cores. Our numerical calculations combined with experiments clarify that these characteristic features are determined by the relative strength of the interterrace Josephson coupling at the atomic step.

  11. Three-dimensional analysis of Eu dopant atoms in Ca-α-SiAlON via through-focus HAADF-STEM imaging

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Genki, E-mail: genki@eng.hokudai.ac.jp; Yamaki, Fuuta; Kunisada, Yuji; Sakaguchi, Norihito; Akiyama, Tomohiro

    2017-04-15

    Highlights: • Through-focus HAADF-STEM imaging was studied. • Spatial distribution of Eu atoms in Ca-α-SiAlON was analyzed. • A large convergence semi-angle increased the depth resolution. • The radial distribution function of Eu dopants was analyzed. - Abstract: Three-dimensional (3D) distributional analysis of individual dopant atoms in materials is important to development of optical, electronic, and magnetic materials. In this study, we adopted through-focus high-angle annular dark-field (HAADF) imaging for 3D distributional analysis of Eu dopant atoms in Ca-α-SiAlON phosphors. In this context, the effects of convergence semi-angle and Eu z-position on the HAADF image contrast were investigated. Multi-slice image simulation revealed that the contrast of the dopant site was sensitive to change of the defocus level. When the defocus level matched the depth position of a Eu atom, the contrast intensity was significantly increased. The large convergence semi-angle greatly increased the depth resolution because the electron beam tends spread instead of channeling along the atomic columns. Through-focus HAADF-STEM imaging was used to analyze the Eu atom distribution surrounding 10 nm cubes with defocus steps of 0.68 nm each. The contrast depth profile recorded with a narrow step width clearly analyzed the possible depth positions of Eu atoms. The radial distribution function obtained for the Eu dopants was analyzed using an atomic distribution model that was based on the assumption of random distribution. The result suggested that the Ca concentration did not affect the Eu distribution. The decreased fraction of neighboring Eu atoms along z-direction might be caused by the enhanced short-range Coulomb-like repulsive forces along the z-direction.

  12. Fabrication and characterization of a 32 x 32 array digital Si-PIN X-ray detector for a single photon counting image sensor

    International Nuclear Information System (INIS)

    Seo, Jungho; Kim, Jinyoung; Lim, Hyunwoo; Park, Jingoo; Lee, Songjun; Kim, Bonghoe; Jeon, Sungchae; Huh, Young

    2010-01-01

    A Si-PIN X-ray detector for digital x-ray imaging with single photon counting capability has been fabricated and characterized. It consists of an array of 32 x 32 pixels with an area of 80 x 80 μm 2 . An extrinsic gettering process was performed to reduce the leakage current by removing the impurities and defects from the X-ray detector's Si substrate. Multiple guard-rings (MGRs) and metal filed plates (MFPs) techniques were adopted to reduce the leakage current and to improve the breakdown performance. The simulation verified that the breakdown voltage was improved with the MGRs and that the leakage current was significantly reduced with the MFPs. The electrical properties, such as the leakage current and the breakdown voltage, of the Si-PIN X-ray detector were characterized. The extrinsic gettering process played a significant role in reducing the leakage current, and a leakage current lower than 60 pA could be achieved at 100 V dc .

  13. Role of targeted magnetic resonance imaging sequences in the surgical management of anterior skull base pathology.

    Science.gov (United States)

    Chawla, S; Bowman, J; Gandhi, M; Panizza, B

    2017-01-01

    The skull base is a highly complex anatomical region that provides passage for important nerves and vessels as they course into and out of the cranial cavity. Key to the management of pathology in this region is a thorough understanding of the anatomy, with its variations, and the relationship of various neurovascular structures to the pathology in question. Targeted high-resolution magnetic resonance imaging on high field strength magnets can enable the skull base surgeon to understand this intricate relationship and deal with the pathology from a position of relative advantage. With the help of case studies, this paper illustrates the application of specialised magnetic resonance techniques to study pathology of the orbital apex in particular. The fine anatomical detail provided gives surgeons the ability to design an endonasal endoscopic procedure appropriate to the anatomy of the pathology.

  14. Aeromonas salmonicida - Epidemiology, whole genome sequencing, detection and in vivo imaging

    DEFF Research Database (Denmark)

    Bartkova, Simona

    causes problems in sea reared rainbow trout (Oncorhynchus mykiss) production. Outbreaks occur repeatedly during stressful conditions such as elevated temperatures, in spite of commercial vaccines being applied. Besides seemingly lacking adequate protection, the vaccines also produce undesirable side...... of the concerns regarding A. salmonicida. First, we focused on investigation of the route of entry and initial dissemination of A. salmonicida in fish. This was done by tracing the bacterium using in vivo bioluminescence imaging. A Danish strain was transformed with a plasmid vector containing a green...... was subsequently turned to finding a sensitive method for detecting A. salmonicida in infected and possible carrier fish. For this, a previously developed quantitative real-time polymerase chain reaction (real-time PCR) targeting the aopP gene located on A. salmonicida plasmid pAsal1 was assessed. The real...

  15. An efficient sequence for fetal brain imaging at 3T with enhanced T1 contrast and motion robustness.

    Science.gov (United States)

    Ferrazzi, Giulio; Price, Anthony N; Teixeira, Rui Pedro A G; Cordero-Grande, Lucilio; Hutter, Jana; Gomes, Ana; Padormo, Francesco; Hughes, Emer; Schneider, Torben; Rutherford, Mary; Kuklisova Murgasova, Maria; Hajnal, Joseph V

    2018-07-01

    Ultrafast single-shot T 2 -weighted images are common practice in fetal MR exams. However, there is limited experience with fetal T 1 -weighted acquisitions. This study aims at establishing a robust framework that allows fetal T 1 -weighted scans to be routinely acquired in utero at 3T. A 2D gradient echo sequence with an adiabatic inversion was optimized to be robust to fetal motion and maternal breathing optimizing grey/white matter contrast at the same time. This was combined with slice to volume registration and super resolution methods to produce volumetric reconstructions. The sequence was tested on 22 fetuses. Optimized grey/white matter contrast and robustness to fetal motion and maternal breathing were achieved. Signal from cerebrospinal fluid (CSF) and amniotic fluid was nulled and 0.75 mm isotropic anatomical reconstructions of the fetal brain were obtained using slice-to-volume registration and super resolution techniques. Total acquisition time for a single stack was 56 s, all acquired during free breathing. Enhanced sensitivity to normal anatomy and pathology with respect to established methods is demonstrated. A direct comparison with a 3D spoiled gradient echo sequence and a controlled motion experiment run on an adult volunteer are also shown. This paper describes a robust framework to perform T 1 -weighted acquisitions and reconstructions of the fetal brain in utero. Magn Reson Med 80:137-146, 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 NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic

  16. Three-Dimensional Constructive Interference in Steady State Sequences and Phase-Contrast Magnetic Resonance Imaging of Arrested Hydrocephalus.

    Science.gov (United States)

    Elkafrawy, Fatma; Reda, Ihab; Elsirafy, Mohamed; Gawad, Mohamed Saied Abdel; Elnaggar, Alaa; Khalek Abdel Razek, Ahmed Abdel

    2017-02-01

    To evaluate the role of three-dimensional constructive interference in steady state (3D-CISS) sequences and phase-contrast magnetic resonance imaging (PC-MRI) in patients with arrested hydrocephalus. A prospective study of 20 patients with arrested hydrocephalus was carried out. All patients underwent PC-MRI and 3D-CISS for assessment of the aqueduct. Axial (through-plane), sagittal (in-plane) PC-MRI, and sagittal 3D-CISS were applied to assess the cerebral aqueduct and the spontaneous third ventriculostomy if present. Aqueductal patency was graded using 3D-CISS and PC-MRI. Quantitative analysis of flow through the aqueduct was performed using PC-MRI. The causes of obstruction were aqueductal obstruction in 75% (n = 15), third ventricular obstruction in 5% (n = 1), and fourth ventricular obstruction in 20% (n = 4). The cause of arrest of hydrocephalus was spontaneous third ventriculostomy in 65% (n = 13), endoscopic third ventriculostomy in 10% (n = 2), and ventriculoperitoneal shunt in 5% (n = 1), and no cause could be detected in 20% of patients (n = 4). There is a positive correlation (r = 0.80) and moderate agreement (κ = 0.509) of grading with PC-MRI and 3D-CISS sequences. The mean peak systolic velocity of cerebrospinal fluid was 1.86 ± 2.48 cm/second, the stroke volume was 6.43 ± 13.81 μL/cycle, and the mean flow was 0.21 ± 0.32 mL/minute. We concluded that 3D-CISS and PC-MRI are noninvasive sequences for diagnosis of the level and cause of arrested hydrocephalus. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. A review of techniques for the identification and measurement of fish in underwater stereo-video image sequences

    Science.gov (United States)

    Shortis, Mark R.; Ravanbakskh, Mehdi; Shaifat, Faisal; Harvey, Euan S.; Mian, Ajmal; Seager, James W.; Culverhouse, Philip F.; Cline, Danelle E.; Edgington, Duane R.

    2013-04-01

    Underwater stereo-video measurement systems are used widely for counting and measuring fish in aquaculture, fisheries and conservation management. To determine population counts, spatial or temporal frequencies, and age or weight distributions, snout to fork length measurements are captured from the video sequences, most commonly using a point and click process by a human operator. Current research aims to automate the measurement and counting task in order to improve the efficiency of the process and expand the use of stereo-video systems within marine science. A fully automated process will require the detection and identification of candidates for measurement, followed by the snout to fork length measurement, as well as the counting and tracking of fish. This paper presents a review of the techniques used for the detection, identification, measurement, counting and tracking of fish in underwater stereo-video image sequences, including consideration of the changing body shape. The review will analyse the most commonly used approaches, leading to an evaluation of the techniques most likely to be a general solution to the complete process of detection, identification, measurement, counting and tracking.

  18. Assessment of Myocardial Fibrosis in Mice Using a T2*-Weighted 3D Radial Magnetic Resonance Imaging Sequence.

    Directory of Open Access Journals (Sweden)

    Bastiaan J van Nierop

    Full Text Available Myocardial fibrosis is a common hallmark of many diseases of the heart. Late gadolinium enhanced MRI is a powerful tool to image replacement fibrosis after myocardial infarction (MI. Interstitial fibrosis can be assessed indirectly from an extracellular volume fraction measurement using contrast-enhanced T1 mapping. Detection of short T2* species resulting from fibrotic tissue may provide an attractive non-contrast-enhanced alternative to directly visualize the presence of both replacement and interstitial fibrosis.To goal of this paper was to explore the use of a T2*-weighted radial sequence for the visualization of fibrosis in mouse heart.C57BL/6 mice were studied with MI (n = 20, replacement fibrosis, transverse aortic constriction (TAC (n = 18, diffuse fibrosis, and as control (n = 10. 3D center-out radial T2*-weighted images with varying TE were acquired in vivo and ex vivo (TE = 21 μs-4 ms. Ex vivo T2*-weighted signal decay with TE was analyzed using a 3-component model. Subtraction of short- and long-TE images was used to highlight fibrotic tissue with short T2*. The presence of fibrosis was validated using histology and correlated to MRI findings.Detailed ex vivo T2*-weighted signal analysis revealed a fast (T2*fast, slow (T2*slow and lipid (T2*lipid pool. T2*fast remained essentially constant. Infarct T2*slow decreased significantly, while a moderate decrease was observed in remote tissue in post-MI hearts and in TAC hearts. T2*slow correlated with the presence of diffuse fibrosis in TAC hearts (r = 0.82, P = 0.01. Ex vivo and in vivo subtraction images depicted a positive contrast in the infarct co-localizing with the scar. Infarct volumes from histology and subtraction images linearly correlated (r = 0.94, P<0.001. Region-of-interest analysis in the in vivo post-MI and TAC hearts revealed significant T2* shortening due to fibrosis, in agreement with the ex vivo results. However, in vivo contrast on subtraction images was rather poor

  19. Driven equilibrium (drive) MR imaging of the cranial nerves V-VIII: comparison with the T2-weighted 3D TSE sequence

    Energy Technology Data Exchange (ETDEWEB)

    Ciftci, E. E-mail: eciftcis7@hotmail.com; Anik, Yonca; Arslan, Arzu; Akansel, Gur; Sarisoy, Tahsin; Demirci, Ali

    2004-09-01

    Purpose: The aim of this study is to evaluate the efficacy of the driven equilibrium radio frequency reset pulse (DRIVE) on image quality and nerve detection when used in adjunction with T2-weighted 3D turbo spin-echo (TSE) sequence. Materials and methods: Forty-five patients with cranial nerve symptoms referable to the cerebellopontine angle (CPA) were examined using a T2-weighted 3D TSE pulse sequence with and without DRIVE. MR imaging was performed on a 1.5-T MRI scanner. In addition to the axial resource images, reformatted oblique sagittal, oblique coronal and maximum intensity projection (MIP) images of the inner ear were evaluated. The nerve identification and image quality were graded for the cranial nerves V-VIII as well as inner ear structures. These structures were chosen because fluid-solid interfaces existed due to the CSF around (the cranial nerves V-VIII) or the endolymph within (the inner ear structures). Statistical analysis was performed using the Wilcoxon test. P<0.05 was considered significant. Results: The addition of the DRIVE pulse shortens the scan time by 25%. T2-weighted 3D TSE sequence with DRIVE performed slightly better than the T2-weighted 3D TSE sequence without DRIVE in identifying the individual nerves. The image quality was also slightly better with DRIVE. Conclusion: The addition of the DRIVE pulse to the T2-weighted 3D TSE sequence is preferable when imaging the cranial nerves surrounded by the CSF, or fluid-filled structures because of shorter scan time and better image quality due to reduced flow artifacts.

  20. Driven equilibrium (drive) MR imaging of the cranial nerves V-VIII: comparison with the T2-weighted 3D TSE sequence

    International Nuclear Information System (INIS)

    Ciftci, E.; Anik, Yonca; Arslan, Arzu; Akansel, Gur; Sarisoy, Tahsin; Demirci, Ali

    2004-01-01

    Purpose: The aim of this study is to evaluate the efficacy of the driven equilibrium radio frequency reset pulse (DRIVE) on image quality and nerve detection when used in adjunction with T2-weighted 3D turbo spin-echo (TSE) sequence. Materials and methods: Forty-five patients with cranial nerve symptoms referable to the cerebellopontine angle (CPA) were examined using a T2-weighted 3D TSE pulse sequence with and without DRIVE. MR imaging was performed on a 1.5-T MRI scanner. In addition to the axial resource images, reformatted oblique sagittal, oblique coronal and maximum intensity projection (MIP) images of the inner ear were evaluated. The nerve identification and image quality were graded for the cranial nerves V-VIII as well as inner ear structures. These structures were chosen because fluid-solid interfaces existed due to the CSF around (the cranial nerves V-VIII) or the endolymph within (the inner ear structures). Statistical analysis was performed using the Wilcoxon test. P<0.05 was considered significant. Results: The addition of the DRIVE pulse shortens the scan time by 25%. T2-weighted 3D TSE sequence with DRIVE performed slightly better than the T2-weighted 3D TSE sequence without DRIVE in identifying the individual nerves. The image quality was also slightly better with DRIVE. Conclusion: The addition of the DRIVE pulse to the T2-weighted 3D TSE sequence is preferable when imaging the cranial nerves surrounded by the CSF, or fluid-filled structures because of shorter scan time and better image quality due to reduced flow artifacts

  1. Imaging different components of a tectonic tremor sequence in southwestern Japan using an automatic statistical detection and location method

    Science.gov (United States)

    Poiata, Natalia; Vilotte, Jean-Pierre; Bernard, Pascal; Satriano, Claudio; Obara, Kazushige

    2018-06-01

    the long-duration energy-release regions, matching the large-scale clustering features evidenced from the low-frequency earthquake's activity analysis. Further examination of the two catalogues showed that the extracted short-duration low-frequency earthquakes activity coincides in space, within about 10-15 km distance, with the longer-duration energy sources during the tectonic tremor sequence. This observation provides a potential constraint on the size of the longer-duration energy-radiating source region in relation with the clustering of low-frequency earthquakes activity during the analysed tectonic tremor sequence. We show that advanced statistical network-based methods offer new capabilities for automatic high-resolution detection, location and monitoring of different scale-components of tectonic tremor activity, enriching existing slow earthquakes catalogues. Systematic application of such methods to large continuous data sets will allow imaging the slow transient seismic energy-release activity at higher resolution, and therefore, provide new insights into the underlying multiscale mechanisms of slow earthquakes generation.

  2. Imaging different components of a tectonic tremor sequence in southwestern Japan using an automatic statistical detection and location method

    Science.gov (United States)

    Poiata, Natalia; Vilotte, Jean-Pierre; Bernard, Pascal; Satriano, Claudio; Obara, Kazushige

    2018-02-01

    the long-duration energy-release regions, matching the large-scale clustering features evidenced from the low-frequency earthquake's activity analysis. Further examination of the two catalogues showed that the extracted short-duration low-frequency earthquakes activity coincides in space, within about 10-15 km distance, with the longer-duration energy sources during the tectonic tremor sequence. This observation provides a potential constraint on the size of the longer-duration energy-radiating source region in relation with the clustering of low-frequency earthquakes activity during the analysed tectonic tremor sequence. We show that advanced statistical network-based methods offer new capabilities for automatic high-resolution detection, location and monitoring of different scale-components of tectonic tremor activity, enriching existing slow earthquakes catalogues. Systematic application of such methods to large continuous data sets will allow imaging the slow transient seismic energy-release activity at higher resolution, and therefore, provide new insights into the underlying multi-scale mechanisms of slow earthquakes generation.

  3. Atomic and electronic structure of trilayer graphene/SiC(0001): Evidence of Strong Dependence on Stacking Sequence and charge transfer.

    Science.gov (United States)

    Pierucci, Debora; Brumme, Thomas; Girard, Jean-Christophe; Calandra, Matteo; Silly, Mathieu G; Sirotti, Fausto; Barbier, Antoine; Mauri, Francesco; Ouerghi, Abdelkarim

    2016-09-15

    The transport properties of few-layer graphene are the directly result of a peculiar band structure near the Dirac point. Here, for epitaxial graphene grown on SiC, we determine the effect of charge transfer from the SiC substrate on the local density of states (LDOS) of trilayer graphene using scaning tunneling microscopy/spectroscopy and angle resolved photoemission spectroscopy (ARPES). Different spectra are observed and are attributed to the existence of two stable polytypes of trilayer: Bernal (ABA) and rhomboedreal (ABC) staking. Their electronic properties strongly depend on the charge transfer from the substrate. We show that the LDOS of ABC stacking shows an additional peak located above the Dirac point in comparison with the LDOS of ABA stacking. The observed LDOS features, reflecting the underlying symmetry of the two polytypes, were reproduced by explicit calculations within density functional theory (DFT) including the charge transfer from the substrate. These findings demonstrate the pronounced effect of stacking order and charge transfer on the electronic structure of trilayer or few layer graphene. Our approach represents a significant step toward understand the electronic properties of graphene layer under electrical field.

  4. In vivo tumor targeting and imaging with engineered trivalent antibody fragments containing collagen-derived sequences.

    Directory of Open Access Journals (Sweden)

    Angel M Cuesta

    Full Text Available There is an urgent need to develop new and effective agents for cancer targeting. In this work, a multivalent antibody is characterized in vivo in living animals. The antibody, termed "trimerbody", comprises a single-chain antibody (scFv fragment connected to the N-terminal trimerization subdomain of collagen XVIII NC1 by a flexible linker. As indicated by computer graphic modeling, the trimerbody has a tripod-shaped structure with three highly flexible scFv heads radially outward oriented. Trimerbodies are trimeric in solution and exhibited multivalent binding, which provides them with at least a 100-fold increase in functional affinity than the monovalent scFv. Our results also demonstrate the feasibility of producing functional bispecific trimerbodies, which concurrently bind two different ligands. A trimerbody specific for the carcinoembryonic antigen (CEA, a classic tumor-associated antigen, showed efficient tumor targeting after systemic administration in mice bearing CEA-positive tumors. Importantly, a trimerbody that recognizes an angiogenesis-associated laminin epitope, showed excellent tumor localization in several cancer types, including fibrosarcomas and carcinomas. These results illustrate the potential of this new antibody format for imaging and therapeutic applications, and suggest that some laminin epitopes might be universal targets for cancer targeting.

  5. Natural image sequences constrain dynamic receptive fields and imply a sparse code.

    Science.gov (United States)

    Häusler, Chris; Susemihl, Alex; Nawrot, Martin P

    2013-11-06

    In their natural environment, animals experience a complex and dynamic visual scenery. Under such natural stimulus conditions, neurons in the visual cortex employ a spatially and temporally sparse code. For the input scenario of natural still images, previous work demonstrated that unsupervised feature learning combined with the constraint of sparse coding can predict physiologically measured receptive fields of simple cells in the primary visual cortex. This convincingly indicated that the mammalian visual system is adapted to the natural spatial input statistics. Here, we extend this approach to the time domain in order to predict dynamic receptive fields that can account for both spatial and temporal sparse activation in biological neurons. We rely on temporal restricted Boltzmann machines and suggest a novel temporal autoencoding training procedure. When tested on a dynamic multi-variate benchmark dataset this method outperformed existing models of this class. Learning features on a large dataset of natural movies allowed us to model spatio-temporal receptive fields for single neurons. They resemble temporally smooth transformations of previously obtained static receptive fields and are thus consistent with existing theories. A neuronal spike response model demonstrates how the dynamic receptive field facilitates temporal and population sparseness. We discuss the potential mechanisms and benefits of a spatially and temporally sparse representation of natural visual input. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Automatically Identifying Fusion Events between GLUT4 Storage Vesicles and the Plasma Membrane in TIRF Microscopy Image Sequences

    Directory of Open Access Journals (Sweden)

    Jian Wu

    2015-01-01

    Full Text Available Quantitative analysis of the dynamic behavior about membrane-bound secretory vesicles has proven to be important in biological research. This paper proposes a novel approach to automatically identify the elusive fusion events between VAMP2-pHluorin labeled GLUT4 storage vesicles (GSVs and the plasma membrane. The differentiation is implemented to detect the initiation of fusion events by modified forward subtraction of consecutive frames in the TIRFM image sequence. Spatially connected pixels in difference images brighter than a specified adaptive threshold are grouped into a distinct fusion spot. The vesicles are located at the intensity-weighted centroid of their fusion spots. To reveal the true in vivo nature of a fusion event, 2D Gaussian fitting for the fusion spot is used to derive the intensity-weighted centroid and the spot size during the fusion process. The fusion event and its termination can be determined according to the change of spot size. The method is evaluated on real experiment data with ground truth annotated by expert cell biologists. The evaluation results show that it can achieve relatively high accuracy comparing favorably to the manual analysis, yet at a small fraction of time.

  7. Pulmonary parenchyma segmentation in thin CT image sequences with spectral clustering and geodesic active contour model based on similarity

    Science.gov (United States)

    He, Nana; Zhang, Xiaolong; Zhao, Juanjuan; Zhao, Huilan; Qiang, Yan

    2017-07-01

    While the popular thin layer scanning technology of spiral CT has helped to improve diagnoses of lung diseases, the large volumes of scanning images produced by the technology also dramatically increase the load of physicians in lesion detection. Computer-aided diagnosis techniques like lesions segmentation in thin CT sequences have been developed to address this issue, but it remains a challenge to achieve high segmentation efficiency and accuracy without much involvement of human manual intervention. In this paper, we present our research on automated segmentation of lung parenchyma with an improved geodesic active contour model that is geodesic active contour model based on similarity (GACBS). Combining spectral clustering algorithm based on Nystrom (SCN) with GACBS, this algorithm first extracts key image slices, then uses these slices to generate an initial contour of pulmonary parenchyma of un-segmented slices with an interpolation algorithm, and finally segments lung parenchyma of un-segmented slices. Experimental results show that the segmentation results generated by our method are close to what manual segmentation can produce, with an average volume overlap ratio of 91.48%.

  8. Biomedical bandpass filter for fluorescence microscopy imaging based on TiO2/SiO2 and TiO2/MgF2 dielectric multilayers

    International Nuclear Information System (INIS)

    Butt, M A; Fomchenkov, S A; Verma, P; Khonina, S N; Ullah, A

    2016-01-01

    We report a design for creating a multilayer dielectric optical filters based on TiO 2 and SiO 2 /MgF 2 alternating layers. We have selected Titanium dioxide (TiO 2 ) for high refractive index (2.5), Silicon dioxide (SiO 2 ) and Magnesium fluoride (MgF 2 ) as a low refractive index layer (1.45 and 1.37) respectively. Miniaturized visible spectrometers are useful for quick and mobile characterization of biological samples. Such devices can be fabricated by using Fabry-Perot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. Distributed Bragg Reflectors (DBRs) consisting of alternating high and low refractive index material pairs are the most commonly used mirrors in FP filters, due to their high reflectivity. However, DBRs have high reflectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer range. Therefore a bandpass filters are required to restrict wavelength outside the stopband of the FP DBRs. The proposed filter shows a high quality with average transmission of 97.4% within the passbands and the transmission outside the passband is around 4%. Special attention has been given to keep the thickness of the filters within the economic limits. It can be suggested that these filters are exceptional choice for florescence imaging and Endoscope narrow band imaging. (paper)

  9. Ag nanodots decorated SiO2 coated ZnO core-shell nanostructure with enhanced luminescence property as potential imaging agent

    Science.gov (United States)

    Gupta, Jagriti; Barick, K. C.; Hassan, P. A.; Bahadur, Dhirendra

    2018-04-01

    Ag decorated silica coated ZnO nanocomposite (Ag@SiO2@ZnO NCs) has been synthesized by soft chemical approach. The physico-chemical properties of Ag@SiO2@ZnO NCs are investigated by various sophisticated characterization techniques such as X-ray diffraction, Transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible absorption and photoluminescent spectroscopy. X-ray diffraction confirms the phase formation of ZnO and Ag in nanocomposite. TEM micrograph clearly shows that Ag nanodots are well decorated over silica coated ZnO NCs. The photoluminescent study reveals the enhancement in the photoluminance property when the Ag nanodots are decorated over silica coated ZnO nanocomposite due to an electromagnetic coupling between excitons and plasmons. Furthermore, the photoluminescent property is an important tool for bio-imaging application, reveal that NCs give green and red emission after excitation with 488 and 535 nm. Therefore, low cytotoxicity and excellent fluorescence stability in vitro makes it a more suitable material for both cellular imaging and therapy for biomedical applications.

  10. Imaging the Spatial Evolution of Degradation in Perovskite/Si Tandem Solar Cells After Exposure to Humid Air

    KAUST Repository

    Song, Zhaoning

    2017-09-14

    Monolithically integrated two-terminal perovskite/Si tandem solar cells promise to achieve high power conversion efficiency. However, there is a concern that the stability of the perovskite top cell will limit the long-term performance of tandem devices. To investigate the impact of perovskite cell degradation on the photocurrent generation and collection in the individual subcells, we employed light beam induced current mapping to spatially resolve the photocurrent under controlled humidity conditions. The evolution of the device behavior is consistent with the formation of an optically transparent hydrated perovskite phase that allows the bottom Si cell to continue to generate photocurrent at the probing wavelength (532 nm). Additional measurements were performed on perovskite thin films on glass substrates to verify the interpretation.

  11. Imaging the Spatial Evolution of Degradation in Perovskite/Si Tandem Solar Cells After Exposure to Humid Air

    KAUST Repository

    Song, Zhaoning; Werner, Jeremie; Watthage, Suneth C.; Sahli, Florent; Shrestha, Niraj; De Wolf, Stefaan; Niesen, Bjorn; Phillips, Adam B.; Ballif, Christophe; Ellingson, Randy J.; Heben, Michael J.

    2017-01-01

    Monolithically integrated two-terminal perovskite/Si tandem solar cells promise to achieve high power conversion efficiency. However, there is a concern that the stability of the perovskite top cell will limit the long-term performance of tandem devices. To investigate the impact of perovskite cell degradation on the photocurrent generation and collection in the individual subcells, we employed light beam induced current mapping to spatially resolve the photocurrent under controlled humidity conditions. The evolution of the device behavior is consistent with the formation of an optically transparent hydrated perovskite phase that allows the bottom Si cell to continue to generate photocurrent at the probing wavelength (532 nm). Additional measurements were performed on perovskite thin films on glass substrates to verify the interpretation.

  12. Imaging of Magnetic Domains and Domain Walls in Spherical Fe-Si Powder Using Magnetic Force Microscopy

    Czech Academy of Sciences Publication Activity Database

    Strečková, M.; Baťková, M.; Baťko, I.; Hadraba, Hynek; Bureš, R.

    2014-01-01

    Roč. 126, č. 1 (2014), s. 92-93 ISSN 0587-4246. [CSMAG Czech and Slovak Conference on Magnetism /15./. Košice, 17.06.2013-21.06.2013] R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : soft magnetic material * Fe-Si * magnetic force microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.530, year: 2014

  13. MR Imaging of the Internal Auditory Canal and Inner Ear at 3T: Comparison between 3D Driven Equilibrium and 3D Balanced Fast Field Echo Sequences

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Jun Soo; Kim, Hyung Jin; Yim, Yoo Jeong; Kim, Sung Tae; Jeon, Pyoung; Kim, Keon Ha [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Sam Soo; Jeon, Yong Hwan; Lee, Ji Won [Kangwon National University College of Medicine, Chuncheon (Korea, Republic of)

    2008-06-15

    To compare the use of 3D driven equilibrium (DRIVE) imaging with 3D balanced fast field echo (bFFE) imaging in the assessment of the anatomic structures of the internal auditory canal (IAC) and inner ear at 3 Tesla (T). Thirty ears of 15 subjects (7 men and 8 women; age range, 22 71 years; average age, 50 years) without evidence of ear problems were examined on a whole-body 3T MR scanner with both 3D DRIVE and 3D bFFE sequences by using an 8-channel sensitivity encoding (SENSE) head coil. Two neuroradiologists reviewed both MR images with particular attention to the visibility of the anatomic structures, including four branches of the cranial nerves within the IAC, anatomic structures of the cochlea, vestibule, and three semicircular canals. Although both techniques provided images of relatively good quality, the 3D DRIVE sequence was somewhat superior to the 3D bFFE sequence. The discrepancies were more prominent for the basal turn of the cochlea, vestibule, and all semicircular canals, and were thought to be attributed to the presence of greater magnetic susceptibility artifacts inherent to gradient-echo techniques such as bFFE. Because of higher image quality and less susceptibility artifacts, we highly recommend the employment of 3D DRIVE imaging as the MR imaging choice for the IAC and inner ear

  14. Contrast-enhanced Magnetic Resonance Imaging of Pelvic Bone Metastases at 3.0 T: Comparison Between 3-dimensional T1-weighted CAIPIRINHA-VIBE Sequence and 2-dimensional T1-weighted Turbo Spin-Echo Sequence.

    Science.gov (United States)

    Yoon, Min A; Hong, Suk-Joo; Lee, Kyu-Chong; Lee, Chang Hee

    2018-06-12

    This study aimed to compare 3-dimensional T1-weighted gradient-echo sequence (CAIPIRINHA-volumetric interpolated breath-hold examination [VIBE]) with 2-dimensional T1-weighted turbo spin-echo sequence for contrast-enhanced magnetic resonance imaging (MRI) of pelvic bone metastases at 3.0 T. Thirty-one contrast-enhanced MRIs of pelvic bone metastases were included. Two contrast-enhanced sequences were evaluated for the following parameters: overall image quality, sharpness of pelvic bone, iliac vessel clarity, artifact severity, and conspicuity and edge sharpness of the smallest metastases. Quantitative analysis was performed by calculating signal-to-noise ratio and contrast-to-noise ratio of the smallest metastases. Significant differences between the 2 sequences were assessed. CAIPIRINHA-VIBE had higher scores for overall image quality, pelvic bone sharpness, iliac vessel clarity, and edge sharpness of the metastatic lesions, and had less artifacts (all P 0.05). Our results suggest that CAIPIRINHA-VIBE may be superior to turbo spin-echo for contrast-enhanced MRI of pelvic bone metastases at 3.0 T.

  15. Low-field MR imaging of the spine. A comparative study of a traditional and a new, completely balanced gradient-echo sequence

    International Nuclear Information System (INIS)

    Drejer, J.; Thomsen, H.S.; Tanttu, J.

    1995-01-01

    49 patients underwent 53 examinations with both a traditional T1-weighted gradient-echo (PS) sequence and a new completely balanced steady-state 3-D (CBASS3D) sequence; 20 examinations included the cervical spine, 8 the thoracic spine and 25 the lumbar spine. All 106 examinations were reviewed twice regarding visibility of selected structures in the spinal region and diagnostic usefulness. The CBASS3D sequence delineated the medulla, nerve roots, CSF, the intervertebral discs and the posterior longitudinal ligament significantly better than the PS sequence. Disc hernia was also better visualised (p<0.01). There were significantly more artefacts on images obtained with the CBASS3D sequence, but they were usually outside the region of interest and occurred less frequently over time due to increased experience of the staff. Both reviewers found the diagnostic usefulness of CBASS3D to be superior compared to that of PS and excellent for diagnostic purposes. (orig./MG)

  16. Low-field MR imaging of the spine. A comparative study of a traditional and a new, completely balanced gradient-echo sequence

    Energy Technology Data Exchange (ETDEWEB)

    Drejer, J. [Dept. of Diagnostic Radiology, Herlev Hospital, Univ. Copenhagen (Denmark); Thomsen, H.S. [Dept. of Diagnostic Radiology, Herlev Hospital, Univ. Copenhagen (Denmark); Tanttu, J. [Picker Nordstar, Helsinki (Finland)

    1995-09-01

    49 patients underwent 53 examinations with both a traditional T1-weighted gradient-echo (PS) sequence and a new completely balanced steady-state 3-D (CBASS3D) sequence; 20 examinations included the cervical spine, 8 the thoracic spine and 25 the lumbar spine. All 106 examinations were reviewed twice regarding visibility of selected structures in the spinal region and diagnostic usefulness. The CBASS3D sequence delineated the medulla, nerve roots, CSF, the intervertebral discs and the posterior longitudinal ligament significantly better than the PS sequence. Disc hernia was also better visualised (p<0.01). There were significantly more artefacts on images obtained with the CBASS3D sequence, but they were usually outside the region of interest and occurred less frequently over time due to increased experience of the staff. Both reviewers found the diagnostic usefulness of CBASS3D to be superior compared to that of PS and excellent for diagnostic purposes. (orig./MG).

  17. Study of temporal sequences of LANSAT images to detect the accumulation of stress prior of strong earthquakes in Chile.

    Science.gov (United States)

    Arellano-Baeza, A. A.

    2016-12-01

    We studied the temporal evolution of the lineaments obtained from the LANSAT-8 associated to the accumulation of stress patterns related to the seismic activity. A lineament is generally defined as a straight or a somewhat curved feature in the landscape visible in a satellite image as an aligned sequence of pixels of a contrasting intensity compared to the background. The system of lineaments extracted from the satellite images is not identical to the geological lineaments; nevertheless, it generally reflects the structure of the faults and fractures in the Earth's crust. The satellite images were processed by the ADALGEO software developed by us. We selected two areas of study with different characteristics. The first area is located near to the Diego de Almagro town in the Copiapo region, Chile. This area did not show any strong seismic activity between 2010 and 2015. However, two strong earthquakes took place later on April 16, 2016 (Mw=5.3) and July 25, 2016 (Mw=6.1). The second area located near the Illapel town in Coquimbo region shows lack of strong earthquakes between 2010 and 2012 and strong seismic activity between 2012 and 2015, culminating by the September 16, 2015 earthquake (Mw=8.3). The distance between two areas is nearly 600 km. In case of the Diego de Almagro area, very few lineaments have been observed between 2010 and 2015, showing a significant increase during the 2016. In case of the Illapel region, the number of lineaments was always much higher, showing an explosive increase at the end of 2015. For both areas the lineaments changed its orientation before strong earthquakes.

  18. Examination of self-navigating MR-sequences for perfusion imaging of the kidneys; Untersuchung von selbstnavigierenden MR-Sequenzen fuer die Perfusionsbildgebung der Nieren

    Energy Technology Data Exchange (ETDEWEB)

    Lietzmann, Florian; Zoellner, Frank G.; Schad, Lothar R. [Heidelberg Univ. Medizinische Fakultaet Mannheim (Germany). Computerunterstuetzte Klinische Medizin; Michaely, Henrik J. [Heidelberg Univ. Medizinische Fakultaet Mannheim (Germany). Inst. fuer Klinische Radiologie und Nuklearmedizin

    2010-07-01

    Due to the worldwide increasing number of cases of chronic kidney diseases renal imaging - as a non-invasive technique in magnetic resonance imaging - has become a very important tool for an early diagnosis of probable insufficiencies and malfunction. Especially, dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) provides a technique to derive physiological parameters like renal blood flow or glomerular filtration rate. Similar to the entire field of abdominal imaging, the major problems are motion artifacts that primarily arise from the patient's respiration. The self-navigating BLADE-sequence with a post processing motion correction is an approach that does not require breath holding and is therefore also easily applicable to patients who are not able to undergo multiple breath hold examinations. In this work, a T1-weighted BLADE-sequence was optimized to demonstrate the feasibility of this technique to perfusion imaging. The number of phase-encoding lines of one BLADE has a direct impact on the reduction of motion artifacts. In comparison to standard DCE-MRI sequences, the developed BLADE-sequence with optimized number of phase encoding lines could significantly reduce motion artifacts. A quantitative analysis revealed that up to a 50% displacement of the kidneys could be corrected. Therefore, it was demonstrated that dynamic motion corrected measurements without the need of a breath hold-technique are feasible. (orig.)

  19. A graphene quantum dot@Fe3O4@SiO2 based nanoprobe for drug delivery sensing and dual-modal fluorescence and MRI imaging in cancer cells.

    Science.gov (United States)

    Su, Xiaoqian; Chan, Chunyu; Shi, Jingyu; Tsang, Ming-Kiu; Pan, Yi; Cheng, Changming; Gerile, Oudeng; Yang, Mo

    2017-06-15

    A novel graphene quantum dot (GQD)@Fe 3 O 4 @SiO 2 based nanoprobe was reported for targeted drug delivery, sensing, dual-modal imaging and therapy. Carboxyl-terminated GQD (C-GQD) was firstly conjugated with Fe 3 O 4 @SiO 2 and then functionalized with cancer targeting molecule folic acid (FA). DOX drug molecules were then loaded on GQD surface of Fe 3 O 4 @SiO 2 @GQD-FA nanoprobe via pi-pi stacking, which resulted in Fe 3 O 4 @SiO 2 @GQD-FA/DOX conjugates based on a FRET mechanism with GQD as donor molecules and DOX as acceptor molecules. Meanwhile, we successfully performed in vitro MRI and fluorescence imaging of living Hela cells and monitored intracellular drug release process using this Fe 3 O 4 @SiO 2 @GQD-FA/DOX nanoprobe. Cell viability study demonstrated the low cytotoxicity of Fe 3 O 4 @SiO 2 @GQD-FA nanocarrier and the enhanced therapeutic efficacy of Fe 3 O 4 @SiO 2 @GQD-FA/DOX nanoprobe for cancer cells. This luminomagnetic nanoprobe will be a potential platform for cancer accurate diagnosis and therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Subjective and objective image qualities: a comparison of sagittal T2 weighted spin-echo and turbo-spin-eco sequences in magnetic resonance imaging of the spine by use of a subjective ranking system

    Energy Technology Data Exchange (ETDEWEB)

    Goerres, G. [Institut fuer diagnostische Radiologie, Departement Radiologie, Universitaetskliniken, Kantonsspital Basel (Switzerland); Mader, I. [Radiologische Gemeinschaftspraxis Dres. Siems, Grossmann, Bayreuth (Germany); Proske, M. [Klinikum Rosenheim (Germany). Inst. fuer Diagnostische Radiologie

    1998-12-31

    We evaluated the subjective image impression of two different magnetic resonance (MR) sequences by using a subjective ranking system. This ranking system was based on 20 criteria describing several tissue characteristics such as the signal intensity of normal anatomical structures and the changes of signal intensities and shape of lesions as well as artefacts. MR of the vertebral spine was performed in 48 female and 52 male patients (mean age 44.8 years) referred consecutively for investigation of a back problem. Ninety-six pathologies were found in 82 patients. Sagittal and axial T1 weighted spin-echo before and after administration of Gadolinium (Gd-DOTA), and sagittal T2 weighted spin-echo (T2wSE) and Turbo-spin-echo (TSE) sequences were performed by means of surface coils. Using the subjective ranking system the sagittal T2wSE and sagittal TSE were compared. Both sequences were suitable for identification of normal anatomy and pathologic changes and there was no trend for increased detection of disease by one imaging sequence over the other. We found that sagittal TSE sequences can replace sagittal T2wSE sequences in spinal MR and that artefacts at the cervical and lumbar spine are less frequent using TSE, thus confirming previous studies. In this study, our ranking system reveiled, that there are differences between the subjective judgement of image qualities and objective measurement of SNR. However, this approach may not be helpful to compare two different MR sequences as it is limited to the anatomical area investigated and is time consuming. The subjective image impression, i.e. the quality of images, may not always be represented by physical parameters such as a signal-to-noise ratio (SNR), radiologists should try to define influences of image quality also by subjective parameters. (orig.)

  1. Time-resolved echo-shared parallel MRA of the lung: observer preference study of image quality in comparison with non-echo-shared sequences

    International Nuclear Information System (INIS)

    Fink, C.; Puderbach, M.; Zaporozhan, J.; Plathow, C.; Kauczor, H.-U.; Ley, S.

    2005-01-01

    The aim of this study was to evaluate the image quality of time-resolved echo-shared parallel MRA of the lung. The pulmonary vasculature of nine patients (seven females, two males; median age: 44 years) with pulmonary disease was examined using a time-resolved MRA sequence combining echo sharing with parallel imaging (time-resolved echo-shared angiography technique, or TREAT). The sharpness of the vessel borders, conspicuousness of peripheral lung vessels, artifact level, and overall image quality of TREAT was assessed independently by four readers in a side-by-side comparison with non-echo-shared time-resolved parallel MRA data (pMRA) previously acquired in the same patients. Furthermore, the SNR of pulmonary arteries (PA) and veins (PV) achieved with both pulse sequences was compared. The mean voxel size of TREAT MRA was decreased by 24% compared with the non-echo-shared MRA. Regarding the sharpness of the vessel borders, conspicuousness of peripheral lung vessels, and overall image quality the TREAT sequence was rated superior in 75-76% of all cases. If the TREAT images were preferred over the pMRA images, the advantage was rated as major in 61-71% of all cases. The level of artifacts was not increased with the TREAT sequence. The mean interobserver agreement for all categories ranged between fair (artifact level) and good (overall image quality). The maximum SNR of TREAT did not differ from non-echo-shared parallel MRA (PA: TREAT: 273±45; pMRA: 280±71; PV: TREAT: 273±33; pMRA: 258±62). TREAT achieves a higher spatial resolution than non-echo-shared parallel MRA which is also perceived as an improved image quality. (orig.)

  2. Dynamics of the magneto structural phase transition in La(Fe{sub 0.9}Co{sub 0.015}Si{sub 0.085}){sub 13} observed by magneto-optical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kuepferling, M., E-mail: m.kuepferling@inrim.it; Basso, V. [Istituto Nazionale di Ricerca Metrologica (INRIM), Strada delle Cacce 91, 10135 Turin (Italy); Bennati, C. [Istituto Nazionale di Ricerca Metrologica (INRIM), Strada delle Cacce 91, 10135 Turin (Italy); Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy); Laviano, F.; Ghigo, G. [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy)

    2014-05-07

    We investigate the temperature induced ferromagnetic to paramagnetic phase transition in Co substituted La(Fe{sub x}Co{sub y}Si{sub 1−x−y}){sub 13} with x = 0.9 and low Co content of y = 0.015 (T{sub c}≃200 K) by means of magneto-optical imaging with indicator film and by calorimetry at very low temperature rates. We were able to visualize the motion of the ferromagnetic (FM)/paramagnetic (PM) front which is forming reproducible patterns independently of the temperature rate. The average velocity of the FM/PM front was calculated to be 10{sup −4} m/s during the continuous propagation and 4×10{sup −3} m/s during an avalanche. The heat flux was measured at low temperature rates by a differential scanning calorimeter and shows a reproducible sequence of individual and separated avalanches which occurs independently of the rate. We interpret the observed effects as the result of the athermal character of the phase transition.

  3. The morphology of ceramic phases in B x C-SiC-Si infiltrated composites

    International Nuclear Information System (INIS)

    Hayun, S.; Frage, N.; Dariel, M.P.

    2006-01-01

    The present communication is concerned with the effect of the carbon source on the morphology of reaction bonded boron carbide (B 4 C). Molten silicon reacts strongly and rapidly with free carbon to form large, faceted, regular polygon-shaped SiC particles, usually embedded in residual silicon pools. In the absence of free carbon, the formation of SiC relies on carbon that originates from within the boron carbide particles. Examination of the reaction bonded boron carbide revealed a core-rim microstructure consisting of boron carbide particles surrounded by secondary boron carbide containing some dissolved silicon. This microstructure is generated as the outcome of a dissolution-precipitation process. In the course of the infiltration process molten Si dissolves some boron carbide until its saturation with B and C. Subsequently, precipitation of secondary boron carbide enriched with boron and silicon takes place. In parallel, elongated, strongly twinned, faceted SiC particles are generated by rapid growth along preferred crystallographic directions. This sequence of events is supported by X-ray diffraction and microcompositional analysis and well accounted for by the thermodynamic analysis of the ternary B-C-Si system. - Graphical abstract: Bright field TEM image of the rim area between two boron carbide grains

  4. Hybrid PET/MR imaging: an algorithm to reduce metal artifacts from dental implants in Dixon-based attenuation map generation using a multiacquisition variable-resonance image combination sequence.

    Science.gov (United States)

    Burger, Irene A; Wurnig, Moritz C; Becker, Anton S; Kenkel, David; Delso, Gaspar; Veit-Haibach, Patrick; Boss, Andreas

    2015-01-01

    It was the aim of this study to implement an algorithm modifying Dixon-based MR imaging datasets for attenuation correction in hybrid PET/MR imaging with a multiacquisition variable resonance image combination (MAVRIC) sequence to reduce metal artifacts. After ethics approval, in 8 oncologic patients with dental implants data were acquired in a trimodality setup with PET/CT and MR imaging. The protocol included a whole-body 3-dimensional dual gradient-echo sequence (Dixon) used for MR imaging-based PET attenuation correction and a high-resolution MAVRIC sequence, applied in the oral area compromised by dental implants. An algorithm was implemented correcting the Dixon-based μ maps using the MAVRIC in areas of Dixon signal voids. The artifact size of the corrected μ maps was compared with the uncorrected MR imaging μ maps. The algorithm was robust in all patients. There was a significant reduction in mean artifact size of 70.5% between uncorrected and corrected μ maps from 697 ± 589 mm(2) to 202 ± 119 mm(2) (P = 0.016). The proposed algorithm could improve MR imaging-based attenuation correction in critical areas, when standard attenuation correction is hampered by metal artifacts, using a MAVRIC. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  5. MR imaging of cranial nerve lesions using six different high-resolution T1- and T2(*)-weighted 3D and 2D sequences

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, J.; Held, P.; Strotzer, M.; Voelk, M.; Nitz, W.R.; Dorenbeck, U.; Feuerbach, S. [Univ. Hospital of Regensburg (Germany). Dept. of Diagnostic Radiology; Stamato, S. [Univ. of California, San Diego, CA (United States). Dept. of Radiology

    2002-07-01

    Purpose: To find a suitable high-resolution MR protocol for the visualization of lesions of all 12 cranial nerves. Material and Methods: Thirty-eight pathologically changed cranial nerves (17 patients) were studied with MR imaging at 1.5T using 3D T2*-weighted CISS, T1-weighted 3D MP-RAGE (without and with i.v. contrast medium), T2-weighted 3D TSE, T2-weighted 2D TSE and T1-weighted fat saturation 2D TSE sequences. Visibility of the 38 lesions of the 12 cranial nerves in each sequence was evaluated by consensus of two radiologists using an evaluation scale from 1 (excellently visible) to 4 (not visible). Results: The 3D CISS sequence provided the best resolution of the cranial nerves and their lesions when surrounded by CSF. In nerves which were not surrounded by CSF, the 2D T1-weighted contrast-enhanced fat suppression technique was the best sequence. Conclusions: A combination of 3D CISS, the 2D T1-weighted fat suppressed sequence and a 3D contrast-enhanced MP-RAGE proved to be the most useful sequence to visualize all lesions of the cranial nerves. For the determination of enhancement, an additional 3D MP-RAGE sequence without contrast medium is required. This sequence is also very sensitive for the detection of hemorrhage.

  6. MR imaging of cranial nerve lesions using six different high-resolution T1- and T2(*)-weighted 3D and 2D sequences

    International Nuclear Information System (INIS)

    Seitz, J.; Held, P.; Strotzer, M.; Voelk, M.; Nitz, W.R.; Dorenbeck, U.; Feuerbach, S.; Stamato, S.

    2002-01-01

    Purpose: To find a suitable high-resolution MR protocol for the visualization of lesions of all 12 cranial nerves. Material and Methods: Thirty-eight pathologically changed cranial nerves (17 patients) were studied with MR imaging at 1.5T using 3D T2*-weighted CISS, T1-weighted 3D MP-RAGE (without and with i.v. contrast medium), T2-weighted 3D TSE, T2-weighted 2D TSE and T1-weighted fat saturation 2D TSE sequences. Visibility of the 38 lesions of the 12 cranial nerves in each sequence was evaluated by consensus of two radiologists using an evaluation scale from 1 (excellently visible) to 4 (not visible). Results: The 3D CISS sequence provided the best resolution of the cranial nerves and their lesions when surrounded by CSF. In nerves which were not surrounded by CSF, the 2D T1-weighted contrast-enhanced fat suppression technique was the best sequence. Conclusions: A combination of 3D CISS, the 2D T1-weighted fat suppressed sequence and a 3D contrast-enhanced MP-RAGE proved to be the most useful sequence to visualize all lesions of the cranial nerves. For the determination of enhancement, an additional 3D MP-RAGE sequence without contrast medium is required. This sequence is also very sensitive for the detection of hemorrhage

  7. Quantification of liver iron concentration with magnetic resonance imaging by combining T1-, T2-weighted spin echo sequences and a gradient echo sequence

    NARCIS (Netherlands)

    Kreeftenberg, HG; Mooyaart, EL; Sluiter, WJ; Kreeftenberg, HG; Huizenga, Reint

    Background: The aim of the study was to quantify hepatic iron by MRI for practical use. Methods: In twenty-three patients with various degrees of iron overload, measurements were carried out with a 1.5 Tesla MR unit. A combination of pulse sequences (T1, T2 and gradient echo) enabled us to quantify

  8. Can a single-shot black-blood T2-weighted spin-echo echo-planar imaging sequence with sensitivity encoding replace the respiratory-triggered turbo spin-echo sequence for the liver? An optimization and feasibility study.

    Science.gov (United States)

    Hussain, Shahid M; De Becker, Jan; Hop, Wim C J; Dwarkasing, Soendersing; Wielopolski, Piotr A

    2005-03-01

    To optimize and assess the feasibility of a single-shot black-blood T2-weighted spin-echo echo-planar imaging (SSBB-EPI) sequence for MRI of the liver using sensitivity encoding (SENSE), and compare the results with those obtained with a T2-weighted turbo spin-echo (TSE) sequence. Six volunteers and 16 patients were scanned at 1.5T (Philips Intera). In the volunteer study, we optimized the SSBB-EPI sequence by interactively changing the parameters (i.e., the resolution, echo time (TE), diffusion weighting with low b-values, and polarity of the phase-encoding gradient) with regard to distortion, suppression of the blood signal, and sensitivity to motion. The influence of each change was assessed. The optimized SSBB-EPI sequence was applied in patients (N = 16). A number of items, including the overall image quality (on a scale of 1-5), were used for graded evaluation. In addition, the signal-to-noise ratio (SNR) of the liver was calculated. Statistical analysis was carried out with the use of Wilcoxon's signed rank test for comparison of the SSBB-EPI and TSE sequences, with P = 0.05 considered the limit for significance. The SSBB-EPI sequence was improved by the following steps: 1) less frequency points than phase-encoding steps, 2) a b-factor of 20, and 3) a reversed polarity of the phase-encoding gradient. In patients, the mean overall image quality score for the optimized SSBB-EPI (3.5 (range: 1-4)) and TSE (3.6 (range: 3-4)), and the SNR of the liver on SSBB-EPI (mean +/- SD = 7.6 +/- 4.0) and TSE (8.9 +/- 4.6) were not significantly different (P > .05). Optimized SSBB-EPI with SENSE proved to be feasible in patients, and the overall image quality and SNR of the liver were comparable to those achieved with the standard respiratory-triggered T2-weighted TSE sequence. (c) 2005 Wiley-Liss, Inc.

  9. Statistical approach of measurement of signal to noise ratio in according to change pulse sequence on brain MRI meningioma and cyst images

    International Nuclear Information System (INIS)

    Lee, Eul Kyu; Choi, Kwan Woo; Jeong, Hoi Woun; Jang, Seo Goo; Kim, Ki Won; Son, Soon Yong; Min, Jung Whan; Son, Jin Hyun

    2016-01-01

    The purpose of this study was to needed basis of measure MRI CAD development for signal to noise ratio (SNR) by pulse sequence analysis from region of interest (ROI) in brain magnetic resonance imaging (MRI) contrast. We examined images of brain MRI contrast enhancement of 117 patients, from January 2005 to December 2015 in a University-affiliated hospital, Seoul, Korea. Diagnosed as one of two brain diseases such as meningioma and cysts SNR for each patient's image of brain MRI were calculated by using Image J. Differences of SNR among two brain diseases were tested by SPSS Statistics21 ANOVA test for there was statistical significance (p < 0.05). We have analysis socio-demographical variables, SNR according to sequence disease, 95% confidence according to SNR of sequence and difference in a mean of SNR. Meningioma results, with the quality of distributions in the order of T1CE, T2 and T1, FLAIR. Cysts results, with the quality of distributions in the order of T2 and T1, T1CE and FLAIR. SNR of MRI sequences of the brain would be useful to classify disease. Therefore, this study will contribute to evaluate brain diseases, and be a fundamental to enhancing the accuracy of CAD development

  10. Statistical approach of measurement of signal to noise ratio in according to change pulse sequence on brain MRI meningioma and cyst images

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eul Kyu [Inje Paik University Hospital Jeo-dong, Seoul (Korea, Republic of); Choi, Kwan Woo [Asan Medical Center, Seoul (Korea, Republic of); Jeong, Hoi Woun [The Baekseok Culture University, Cheonan (Korea, Republic of); Jang, Seo Goo [The Soonchunhyang University, Asan (Korea, Republic of); Kim, Ki Won [Kyung Hee University Hospital at Gang-dong, Seoul (Korea, Republic of); Son, Soon Yong [The Wonkwang Health Science University, Iksan (Korea, Republic of); Min, Jung Whan; Son, Jin Hyun [The Shingu University, Sungnam (Korea, Republic of)

    2016-09-15

    The purpose of this study was to needed basis of measure MRI CAD development for signal to noise ratio (SNR) by pulse sequence analysis from region of interest (ROI) in brain magnetic resonance imaging (MRI) contrast. We examined images of brain MRI contrast enhancement of 117 patients, from January 2005 to December 2015 in a University-affiliated hospital, Seoul, Korea. Diagnosed as one of two brain diseases such as meningioma and cysts SNR for each patient's image of brain MRI were calculated by using Image J. Differences of SNR among two brain diseases were tested by SPSS Statistics21 ANOVA test for there was statistical significance (p < 0.05). We have analysis socio-demographical variables, SNR according to sequence disease, 95% confidence according to SNR of sequence and difference in a mean of SNR. Meningioma results, with the quality of distributions in the order of T1CE, T2 and T1, FLAIR. Cysts results, with the quality of distributions in the order of T2 and T1, T1CE and FLAIR. SNR of MRI sequences of the brain would be useful to classify disease. Therefore, this study will contribute to evaluate brain diseases, and be a fundamental to enhancing the accuracy of CAD development.

  11. Improved imaging of cochlear nerve hypoplasia using a 3-Tesla variable flip-angle turbo spin-echo sequence and a 7-cm surface coil.

    Science.gov (United States)

    Giesemann, Anja M; Raab, Peter; Lyutenski, Stefan; Dettmer, Sabine; Bültmann, Eva; Frömke, Cornelia; Lenarz, Thomas; Lanfermann, Heinrich; Goetz, Friedrich

    2014-03-01

    Magnetic resonance imaging of the temporal bone has an important role in decision making with regard to cochlea implantation, especially in children with cochlear nerve deficiency. The purpose of this study was to evaluate the usefulness of the combination of an advanced high-resolution T2-weighted sequence with a surface coil in a 3-Tesla magnetic resonance imaging scanner in cases of suspected cochlear nerve aplasia. Prospective study. Seven patients with cochlear nerve hypoplasia or aplasia were prospectively examined using a high-resolution three-dimensional variable flip-angle turbo spin-echo sequence using a surface coil, and the images were compared with the same sequence in standard resolution using a standard head coil. Three neuroradiologists evaluated the magnetic resonance images independently, rating the visibility of the nerves in diagnosing hypoplasia or aplasia. Eight ears in seven patients with hypoplasia or aplasia of the cochlear nerve were examined. The average age was 2.7 years (range, 9 months-5 years). Seven ears had accompanying malformations. The inter-rater reliability in diagnosing hypoplasia or aplasia was greater using the high-resolution three-dimensional variable flip-angle turbo spin-echo sequence (fixed-marginal kappa: 0.64) than with the same sequence in lower resolution (fixed-marginal kappa: 0.06). Examining cases of suspected cochlear nerve aplasia using the high-resolution three-dimensional variable flip-angle turbo spin-echo sequence in combination with a surface coil shows significant improvement over standard methods. © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

  12. The use of phase sequence image sets to reconstruct the total volume occupied by a mobile lung tumor

    International Nuclear Information System (INIS)

    Gagne, Isabelle M.; Robinson, Don M.; Halperin, Ross; Roa, Wilson

    2005-01-01

    The use of phase sequence image (PSI) sets to reveal the total volume occupied by a mobile target is presented. Isocontrast composite clinical target volumes (CCTVs) may be constructed from PSI sets in order to reveal the total volume occupied by a mobile target during the course of its travel. The ability of the CCTV technique to properly account for target motion is demonstrated by comparison to contours of the true total volume occupied (TVO) for a number of experimental phantom geometries. Finally, using real patient data, the clinical utility of the CCTV technique to properly account for internal tumor motion while minimizing the volume of healthy lung tissue irradiated is assessed by comparison to the standard approach of applying safety margins. Results of the phantom study reveal that CCTV cross sections constructed at the 20% isocontrast level yield good agreement with the total cross sections (TXO) of mobile targets. These CCTVs conform well to the TVOs of the moving targets examined whereby the addition of small uniform margins ensures complete circumscription of the TVO with the inclusion of minimal amounts of surrounding external volumes. The CCTV technique is seen to be clearly superior to the common practice of the addition of safety margins to individual CTV contours in order to account for internal target motion. Margins required with the CCTV technique are eight to ten times smaller than those required with individual CTVs

  13. Characterization of imaging pixel detectors of Si and CdTe read out with the counting X-ray chip MPEC 2.3

    International Nuclear Information System (INIS)

    Loecker, M.

    2007-04-01

    Single photon counting detectors with Si- and CdTe-sensors have been constructed and characterized. As readout chip the MPEC 2.3 is used which consists of 32 x 32 pixels with 200 x 200 μm 2 pixel size and which has a high count rate cabability (1 MHz per pixel) as well as a low noise performance (55 e - ). Measurements and simulations of the detector homogeneity are presented. It could be shown that the theoretical maximum of the homogeneity is reached (quantum limit). By means of the double threshold of the MPEC chip the image contrast can be enhanced which is demonstrated by measurement and simulation. Also, multi-chip-modules consisting of 4 MPEC chips and a single Si- or CdTe-sensor have been constructed and successfully operated. With these modules modulation-transfer-function measurements have been done showing a good spatial resolution of the detectors. In addition, multi-chip-modules according to the Sparse-CMOS concept have been built and tests characterizing the interconnection technologies have been performed

  14. Correlation between morphological defects, electron beam-induced current imaging, and the electrical properties of 4H-SiC Schottky diodes

    International Nuclear Information System (INIS)

    Wang, Y.; Ali, G.N.; Mikhov, M.K.; Vaidyanathan, V.; Skromme, B.J.; Raghothamachar, B.; Dudley, M.

    2005-01-01

    Defects in SiC degrade the electrical properties and yield of devices made from this material. This article examines morphological defects in 4H-SiC and defects visible in electron beam-induced current (EBIC) images and their effects on the electrical characteristics of Schottky diodes. Optical Nomarski microscopy and atomic force microscopy were used to observe the morphological defects, which are classified into 26 types based on appearance alone. Forward and reverse current-voltage characteristics were used to extract barrier heights, ideality factors, and breakdown voltages. Barrier heights decrease about linearly with increasing ideality factor, which is explained by discrete patches of low barrier height within the main contact. Barrier height, ideality, and breakdown voltage all degrade with increasing device diameter, suggesting that discrete defects are responsible. Electroluminescence was observed under reverse bias from microplasmas associated with defects containing micropipes. EBIC measurements reveal several types of features corresponding to recombination centers. The density of dark spots observed by EBIC correlates strongly with ideality factor and barrier height. Most morphological defects do not affect the reverse characteristics when no micropipes are present, but lower the barrier height and worsen the ideality factor. However, certain multiple-tailed defects, irregularly shaped defects and triangular defects with 3C inclusions substantially degrade both breakdown voltage and barrier height, and account for most of the bad devices that do not contain micropipes. Micropipes in these wafers are also frequently found to be of Type II, which do not run parallel to the c axis

  15. Imaging the Crust in the Northern Sector of the 2009 L'Aquila Seismic Sequence through Oil Exploration Data Interpretation

    Science.gov (United States)

    Grazia Ciaccio, Maria; Improta, Luigi; Patacca, Etta; Scandone, Paolo; Villani, Fabio

    2010-05-01

    The 2009 L'Aquila seismic sequence activated a complex, about 40 km long, NW-trending and SW-dipping normal fault system, consisting of three main faults arranged in right-lateral en-echelon geometry. While the northern sector of the epicentral area was extensively investigated by oil companies, only a few scattered, poor-quality commercial seismic profiles are available in the central and southern sector. In this study we interpret subsurface commercial data from the northern sector, which is the area where is located the source of the strong Mw5.4 aftershock occurred on the 9th April 2009. Our primary goals are: (1) to define a reliable framework of the upper crust structure, (2) to investigate how the intense aftershock activity, the bulk of which is clustered in the 5-10 km depth range, relates to the Quaternary extensional faults present in the area. The investigated area lies between the western termination of the W-E trending Gran Sasso thrust system to the south, the SW-NE trending Mt. Sibillini thrust front (Ancona-Anzio Line Auctt.) to the north and west, and by the NNW-SSE trending, SW-dipping Mt. Gorzano normal fault to the east. In this area only middle-upper Miocene deposits are exposed (Laga Flysch and underlying Cerrogna Marl), but commercial wells have revealed the presence of a Triassic-Miocene sedimentary succession identical to the well known Umbria-Marche stratigraphic sequence. We have analyzed several confidential seismic reflection profiles, mostly provided by ENI oil company. Seismic lines are tied to two public wells, 5766 m and 2541 m deep. Quality of the reflection imaging is highly variable. A few good quality stack sections contain interpretable signal down to 4.5-5.5 s TWT, corresponding to depths exceeding 10-12 km and thus allowing crustal imaging at seismogenic depths. Key-reflectors for the interpretation correspond to: (1) the top of the Miocene Cerrogna marls, (2) the top of the Upper Albian-Oligocene Scaglia Group, (3) the

  16. Cartilage volume quantification with multi echo data image combination sequence in swine knee at 3.0 T MRI

    International Nuclear Information System (INIS)

    Zhang Lirong; Wang Dongqing; Wei Chuanshe; Ma Cong; Wang Dehang

    2010-01-01

    Objective: To investigate the accuracy and reproducibility of multi echo data imagine combination (MEDIC) sequence with water excitation at 3.0 T in swine knee cartilage. Methods: Sagittal MEDIC sequences (0.6 mm slice thickness, isotropic) were acquired twice at 3.0 T MRI in 30 swine knees. The knee cartilage was then removed and the volume was directly measured with water substitution method. The cartilage volume was also determined with a validated open source image software OsiriX by two observers (A and B). The cartilage volumes obtained by two methods were compared. The reproducibility of MEDIC for quantitative measurement was accessed by the root-mean-square (RMS) of variation coefficient. Interobserver and intraobserver precision errors were compared using a paired students t-test. The accuracy of MEDIC for quantitative measurement was determined by the random pairwise differences, systematic pairwise differences and the Pearson, correlation coefficients. Time of semiautomatic and manual segmentation were recorded. Results: Time was saved about 75% by using semiautomatic segmentation methods [(4.0± 1.5) min] versus manual segmentation [(16.0±0.9) min]. Interobserver precision errors (RMS CV% for paired analysis) between A and B for cartilage volume measurement were (2.66±0.82) ml and(2.61± 0.81) ml, t=0.24, P=0.81 (patella); (2.40±0.69) ml and (2.49±0.85) ml, t=-0.45, P=0.65 (medial femoral condyle); (2.28±0.74) ml and(2.41±0.78) ml, t=-0.66, P=0.51 (lateral femoral condyle); (3.43±1.28) ml and (3.51±1.08) ml, t=-0.26, P=0.79 (femora trochlea) with sagittal MEDIC. Intraobserver precision errors (RMS CV% for paired analysis) of observer A for the first and second cartilage volume measurement were (2.64±0.62) ml and (2.67±0.60) ml, t=-0.19, P=0.85 (patella); (2.43±0.60) ml and (2.39±0.59) ml, t=0.26, P=0.80 (medial femoral condyle); (2.26±0.56) ml and (2.30±0.57) ml, t=-0.27, P=0.78 (lateral femoral condyle); (3.40± 1.20) ml and (3.47±1

  17. Computation of the lamina stacking sequence effect on elastic moduli of a plain-weave Nicalon/SiC laminated composite with a [0/30/60] lay-up

    International Nuclear Information System (INIS)

    Zhao Wei; Yu Niann-i

    1998-01-01

    Estimation of the elastic modulus is important in engineering design. One difference between CFCCs (continuous fiber-reinforced ceramic-matrix composites), and CMCs (whisker, particulate, or short fiber-reinforced ceramic-matrix composites), is that the anisotropic behavior of CFCCs plays an important role in affecting their mechanical behavior. This feature may also contribute to the variation of elastic properties and strengths of CFCC. In this paper, a Fortran program is developed to quantify the lamina stacking sequence effect on the effective elastic moduli of the laminated CFCCs. The material for modeling is a plain-weave Nicalon fiber-reinforced silicon carbide (Nicalon/SiC) CFCCs. Results show that various stacking sequences within the CFCC (a [0/30/60] lay-up) will give different effective elastic moduli of the CFCCs. This trend leads to a variation of the slope of the linear portion on the flexural stress-strain curve, i.e., changing the position of the starting point of the non-linear portion, and the shape of the whole curve, which gives a different value of the peak stress in the curve. (orig.)

  18. Imaging 2015 Mw 7.8 Gorkha Earthquake and Its Aftershock Sequence Combining Multiple Calibrated Global Seismic Arrays

    Science.gov (United States)

    LI, B.; Ghosh, A.

    2016-12-01

    The 2015 Mw 7.8 Gorkha earthquake provides a good opportunity to study the tectonics and earthquake hazards in the Himalayas, one of the most seismically active plate boundaries. Details of the seismicity patterns and associated structures in the Himalayas are poorly understood mainly due to limited instrumentation. Here, we apply a back-projection method to study the mainshock rupture and the following aftershock sequence using four large aperture global seismic arrays. All the arrays show eastward rupture propagation of about 130 km and reveal similar evolution of seismic energy radiation, with strong high-frequency energy burst about 50 km north of Kathmandu. Each single array, however, is typically limited by large azimuthal gap, low resolution, and artifacts due to unmodeled velocity structures. Therefore, we use a self-consistent empirical calibration method to combine four different arrays to image the Gorkha event. It greatly improves the resolution, can better track rupture and reveal details that cannot be resolved by any individual array. In addition, we also use the same arrays at teleseismic distances and apply a back-projection technique to detect and locate the aftershocks immediately following the Gorkha earthquake. We detect about 2.5 times the aftershocks recorded by the Advance National Seismic System comprehensive earthquake catalog during the 19 days following the mainshock. The aftershocks detected by the arrays show an east-west trend in general, with majority of the aftershocks located at the eastern part of the rupture patch and surrounding the rupture zone of the largest Mw 7.3 aftershock. Overall spatiotemporal aftershock pattern agrees well with global catalog, with our catalog showing more details relative to the standard global catalog. The improved aftershock catalog enables us to better study the aftershock dynamics, stress evolution in this region. Moreover, rapid and better imaging of aftershock distribution may aid rapid response

  19. Imaging lysosomal highly reactive oxygen species and lighting up cancer cells and tumors enabled by a Si-rhodamine-based near-infrared fluorescent probe.

    Science.gov (United States)

    Zhang, Hongxing; Liu, Jing; Liu, Chenlu; Yu, Pengcheng; Sun, Minjia; Yan, Xiaohan; Guo, Jian-Ping; Guo, Wei

    2017-07-01

    Lysosomes have recently been regarded as the attractive pharmacological targets for selectively killing of cancer cells via lysosomal cell death (LCD) pathway that is closely associated with reactive oxygen species (ROS). However, the details on the ROS-induced LCD of cancer cells are still poorly understood, partially due to the absence of a lysosome-targetable, robust, and biocompatible imaging tool for ROS. In this work, we brought forward a Si-rhodamine-based fluorescent probe, named PSiR, which could selectively and sensitively image the pathologically more relavent highly reactive oxygen species (hROS: HClO, HO, and ONOO - ) in lysosomes of cancer cells. Compared with many of the existing hROS fluorescent probes, its superiorities are mainly embodied in the high stability against autoxidation and photoxidation, near-infrared exitation and emission, fast fluorescence off-on response, and specific lysosomal localization. Its practicality has been demonstrated by the real-time imaging of hROS generation in lysosomes of human non-small-cell lung cancer cells stimulated by anticancer drug β-lapachone. Moreover, the probe was sensitive enough for basal hROS in cancer cells, allowing its further imaging applications to discriminate not only cancer cells from normal cells, but also tumors from healthy tissues. Overall, our results strongly indicated that PSiR is a very promising imaging tool for the studies of ROS-related LCD of cancer cells, screening of new anticancer drugs, and early diagnosis of cancers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Effect of interfacial SiO2- y layer and defect in HfO2- x film on flat-band voltage of HfO2- x /SiO2- y stacks for backside-illuminated CMOS image sensors

    Science.gov (United States)

    Na, Heedo; Lee, Jimin; Jeong, Juyoung; Kim, Taeho; Sohn, Hyunchul

    2018-03-01

    In this study, the effect of oxygen gas fraction during deposition of a hafnium oxide (HfO2- x ) film and the influence of the quality of the SiO2- y interlayer on the nature of flat-band voltage ( V fb) in TiN/HfO/SiO2- y /p-Si structures were investigated. X-ray photoemission spectroscopy analysis showed that the non-lattice oxygen peak, indicating an existing oxygen vacancy, increased as the oxygen gas fraction decreased during sputtering. From C- V and J- E analyses, the V fb behavior was significantly affected by the characteristics of the SiO2- y interlayer and the non-lattice oxygen fraction in the HfO2- x films. The HfO2- x /native SiO2- y stack presented a V fb of - 1.01 V for HfO2- x films with an oxygen gas fraction of 5% during sputtering. Additionally, the V fb of the HfO2- x /native SiO2- y stack could be controlled from - 1.01 to - 0.56 V by changing the deposition conditions of the HfO2- x film with the native SiO2- y interlayer. The findings of this study can be useful to fabricate charge-accumulating layers for backside-illuminated image sensor devices.

  1. TrueFisp versus HASTE sequences in 3T cine MRI: Evaluation of image quality during phonation in patients with velopharyngeal insufficiency

    International Nuclear Information System (INIS)

    Kulinna-Cosentini, Christiane; Czerny, Christian; Weber, Michael; Baumann, Arnulf; Sinko, Klaus

    2016-01-01

    To evaluate the image quality of two fast dynamic magnetic resonance imaging (MRI) sequences: True fast imaging with steady state precession (TrueFisp) was compared with half-Fourier acquired single turbo-spin-echo (HASTE) sequence for the characterization of velopharyngeal insufficiency (VPI) in repaired cleft palate patients. Twenty-two patients (10 female and 12 male; mean age, 17.7 ± 10.6 years; range, 9-31) with suspected VPI underwent 3-T MRI using TrueFisp and HASTE sequences. Imaging was performed in the sagittal plane at rest and during phonation of ''ee'' and ''k'' to assess the velum, tongue, posterior pharyngeal wall and a potential VP closure. The results were analysed independently by one radiologist and one orthodontist. HASTE performed better than TrueFisp for all evaluated items, except the tongue evaluation by the orthodontist during phonation of ''k'' and ''ee''. A statistically significant difference in favour of HASTE was observed in assessing the velum at rest and during phonation of ''k'' and ''ee'', and also in assessing VP closure in both raters (p < 0.05). TrueFisp imaging was twice as fast as HASTE (0.36 vs. 0.75 s/image). Dynamic HASTE images were of superior quality to those obtained with TrueFisp, although TrueFisp imaging was twice as fast. (orig.)

  2. Comparing an accelerated 3D fast spin-echo sequence (CS-SPACE) for knee 3-T magnetic resonance imaging with traditional 3D fast spin-echo (SPACE) and routine 2D sequences

    Energy Technology Data Exchange (ETDEWEB)

    Altahawi, Faysal F.; Blount, Kevin J.; Omar, Imran M. [Northwestern University Feinberg School of Medicine, Department of Radiology, Chicago, IL (United States); Morley, Nicholas P. [Marshfield Clinic, Department of Radiology, Marshfield, WI (United States); Raithel, Esther [Siemens Healthcare GmbH, Erlangen (Germany)

    2017-01-15

    To compare a faster, new, high-resolution accelerated 3D-fast-spin-echo (3D-FSE) acquisition sequence (CS-SPACE) to traditional 2D and high-resolution 3D sequences for knee 3-T magnetic resonance imaging (MRI). Twenty patients received knee MRIs that included routine 2D (T1, PD ± FS, T2-FS; 0.5 x 0.5 x 3 mm{sup 3}; ∝10 min), traditional 3D FSE (SPACE-PD-FS; 0.5 x 0.5 x 0.5 mm{sup 3}; ∝7.5 min), and accelerated 3D-FSE prototype (CS-SPACE-PD-FS; 0.5 x 0.5 x 0.5 mm{sup 3}; ∝5 min) acquisitions on a 3-T MRI system (Siemens MAGNETOM Skyra). Three musculoskeletal radiologists (MSKRs) prospectively and independently reviewed the studies with graded surveys comparing image and diagnostic quality. Tissue-specific signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were also compared. MSKR-perceived diagnostic quality of cartilage was significantly higher for CS-SPACE than for SPACE and 2D sequences (p < 0.001). Assessment of diagnostic quality of menisci and synovial fluid was higher for CS-SPACE than for SPACE (p < 0.001). CS-SPACE was not significantly different from SPACE but had lower assessments than 2D sequences for evaluation of bones, ligaments, muscles, and fat (p ≤ 0.004). 3D sequences had higher spatial resolution, but lower overall assessed contrast (p < 0.001). Overall image quality from CS-SPACE was assessed as higher than SPACE (p = 0.007), but lower than 2D sequences (p < 0.001). Compared to SPACE, CS-SPACE had higher fluid SNR and CNR against all other tissues (all p < 0.001). The CS-SPACE prototype allows for faster isotropic acquisitions of knee MRIs over currently used protocols. High fluid-to-cartilage CNR and higher spatial resolution over routine 2D sequences may present a valuable role for CS-SPACE in the evaluation of cartilage and menisci. (orig.)

  3. Comparison of 3D two-point Dixon and standard 2D dual-echo breath-hold sequences for detection and quantification of fat content in renal angiomyolipoma

    International Nuclear Information System (INIS)

    Rosenkrantz, Andrew B.; Raj, Sean; Babb, James S.; Chandarana, Hersh

    2012-01-01

    Purpose: To assess the utility of a 3D two-point Dixon sequence with water–fat decomposition for quantification of fat content of renal angiomyolipoma (AML). Methods: 84 patients underwent renal MRI including 2D in-and-opposed-phase (IP and OP) sequence and 3D two-point Dixon sequence that generates four image sets [IP, OP, water-only (WO), and fat-only (FO)] within one breath-hold. Two radiologists reviewed 2D and 3D images during separate sessions to identify fat-containing renal masses measuring at least 1 cm. For identified lesions subsequently confirmed to represent AML, ROIs were placed at matching locations on 2D and 3D images and used to calculate 2D and 3D SI index [(SI IP − SI OP )/SI IP ] and 3D fat fraction (FF) [SI FO /(SI FO + SI WO )]. 2D and 3D SI index were compared with 3D FF using Pearson correlation coefficients. Results: 41 AMLs were identified in 6 patients. While all were identified using the 3D sequence, 39 were identified using the 2D sequence, with the remaining 2 AMLs retrospectively visible on 2D images but measuring under 1 cm. Among 32 AMLs with a 3D FF of over 50%, both 2D and 3D SI index showed a statistically significant inverse correlation with 3D FF (2D SI index : r = −0.63, p = 0.0010; 3D SI index : r = −0.97, p index , is not limited by ambiguity of water or fat dominance. This may assist clinical management of AML given evidence that fat content predicts embolization response.

  4. PINPIN a-Si:H based structures for X-ray image detection using the laser scanning technique

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, M., E-mail: mfernandes@isel.pt [Electronics Telecommunication and Computer Dept., ISEL, R.Conselheiro Emídio Navarro, 1959-007 Lisboa (Portugal); CTS-UNINOVA Quinta da Torre, Monte da Caparica, 2829-516 Caparica (Portugal); Vygranenko, Y.; Vieira, M. [Electronics Telecommunication and Computer Dept., ISEL, R.Conselheiro Emídio Navarro, 1959-007 Lisboa (Portugal); CTS-UNINOVA Quinta da Torre, Monte da Caparica, 2829-516 Caparica (Portugal)

    2015-05-01

    Highlights: • We present novel structure for X-ray image sensor based on the laser scanned technique. • Amorphous silicon based tandem structure characterization results are presented and discussed. • Results from preliminary tests of the imaging application are promising for very large area image sensing. - Abstract: Conventional film based X-ray imaging systems are being replaced by their digital equivalents. Different approaches are being followed by considering direct or indirect conversion, with the later technique dominating. The typical, indirect conversion, X-ray panel detector uses a phosphor for X-ray conversion coupled to a large area array of amorphous silicon based optical sensors and a couple of switching thin film transistors (TFT). The pixel information can then be readout by switching the correspondent line and column transistors, routing the signal to an external amplifier. In this work we follow an alternative approach, where the electrical switching performed by the TFT is replaced by optical scanning using a low power laser beam and a sensing/switching PINPIN structure, thus resulting in a simpler device. The optically active device is a PINPIN array, sharing both front and back electrical contacts, deposited over a glass substrate. During X-ray exposure, each sensing side photodiode collects photons generated by the scintillator screen (560 nm), charging its internal capacitance. Subsequently a laser beam (445 nm) scans the switching diodes (back side) retrieving the stored charge in a sequential way, reconstructing the image. In this paper we present recent work on the optoelectronic characterization of the PINPIN structure to be incorporated in the X-ray image sensor. The results from the optoelectronic characterization of the device and the dependence on scanning beam parameters are presented and discussed. Preliminary results of line scans are also presented.

  5. High-resolution T2-weighted MR imaging of the inner ear using a long echo-train-length 3D fast spin-echo sequence

    International Nuclear Information System (INIS)

    Naganawa, S.; Yamakawa, K.; Fukatsu, H.; Ishigaki, T.; Nakashima, T.; Sugimoto, H.; Aoki, I.; Miyazaki, M.; Takai, H.

    1996-01-01

    The purpose of this study was to assess the value of a long echo-train-length 3D fast spin-echo (3D-FSE) sequence in visualizing the inner ear structures. Ten normal ears and 50 patient ears were imaged on a 1.5T MR unit using a head coil. Axial high-resolution T2-weighted images of the inner ear and the internal auditory canal (IAC) were obtained in 15 min. In normal ears the reliability of the visualization for the inner ear structures was evaluated on original images and the targeted maximum intensity projection (MIP) images of the labyrinth. In ten normal ears, 3D surface display (3D) images were also created and compared with MIP images. On the original images the cochlear aqueduct, the vessels in the vicinity of the IAC, and more than three branches of the cranial nerves were visualized in the IAC in all the ears. The visibility of the endolympathic duct was 80%. On the MIP images the visibility of the three semicircular canals, anterior and posterior ampulla, and of more than two turns of the cochlea was 100%. The MIP images and 3D images were almost comparable. The visibility of the endolymphatic duct was 80% in normal ears and 0% in the affected ears of the patients with Meniere's disease (p<0.001). In one patient ear a small intracanalicular tumor was depicted clearly. In conclusion, the long echo train length T2-weighted 3D-FSE sequence enables the detailed visualization of the tiny structures of the inner ear and the IAC within a clinically acceptable scan time. Furthermore, obtaining a high contrast between the soft/bony tissue and the cerebrospinal/endolymph/perilymph fluid would be of significant value in the diagnosis of the pathologic conditions around the labyrinth and the IAC. (orig.)

  6. Readout-segmented echo-planar imaging improves the image quality of diffusion-weighted MR imaging in rectal cancer: Comparison with single-shot echo-planar diffusion-weighted sequences

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Chun-chao; Liu, Xi; Peng, Wan-lin; Li, Lei; Zhang, Jin-ge [Department of Radiology, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, Sichuan 610041 (China); Meng, Wen-jian; Deng, Xiang-bing [Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, Sichuan 610041 (China); Zuo, Pan-li [Siemens Healthcare, MR Collaborations NE Asia, 100010, Beijing (China); Li, Zhen-lin, E-mail: lzlcd01@126.com [Department of Radiology, West China Hospital, Sichuan University, 37# Guo Xue Xiang, Chengdu, Sichuan 610041 (China)

    2016-10-15

    Purpose: To determine whether readout-segmented echo-planar imaging (rs-EPI) diffusion-weighted imaging (DWI) can improve the image quality in patients with rectal cancer compared with single-shot echo-planar imaging (ss-EPI) DWI using 3.0 T magnetic resonance (MR) imaging. Materials and methods: This study was approved by the Institutional Review Board, and informed consent was obtained from all patients. Seventy-one patients with rectal cancer were enrolled in this study. For all patients, both rs-EPI and ss-EPI DWI were performed using a 3T MR scanner. Two radiologists independently assessed the overall image quality, lesion conspicuity, geometric distortion and distinction of anatomical structures. The signal-to-noise ratio (SNR), lesion contrast, contrast-to-noise ratio (CNR), and apparent diffusion coefficient (ADC) were also measured. Comparisons of the quantitative and qualitative parameters between the two sequences were performed using the paired t-test and the Wilcoxon signed rank test. Results: The scores of overall image quality, lesion conspicuity, geometric distortion and distinction of anatomical structures of rs-EPI were all significantly higher than those of ss-EPI (all p < 0.05). The SNR and CNR were higher in rs-EPI than those in ss-EPI (all p < 0.05). There was no significant difference between ss-EPI and rs-EPI with regard to ROI size and mean ADCs of the tumour (p = 0.574 and p = 0.479, respectively), but the mean ADC of the normal tissue was higher in rs-EPI than in ss-EPI (1.73 ± 0.30 × 10{sup −3} mm{sup 2}/s vs. 1.60 ± 0.31 × 10{sup −3} mm{sup 2}/s, p = 0.001). Conclusions: DW imaging based on readout-segmented echo-planar imaging is a clinically useful technique to improve the image quality for the purpose of evaluating lesions in patients with rectal tumours.

  7. Deep sequencing of small RNAs identifies canonical and non-canonical miRNA and endogenous siRNAs in mammalian somatic tissues.

    Science.gov (United States)

    Castellano, Leandro; Stebbing, Justin

    2013-03-01

    MicroRNAs (miRNAs) are small RNA molecules that regulate gene expression. They are characterized by specific maturation processes defined by canonical and non-canonical biogenic pathways. Analysis of ∼0.5 billion sequences from mouse data sets derived from different tissues, developmental stages and cell types, partly characterized by either ablation or mutation of the main proteins belonging to miRNA processor complexes, reveals 66 high-confidence new genomic loci coding for miRNAs that could be processed in a canonical or non-canonical manner. A proportion of the newly discovered miRNAs comprises mirtrons, for which we define a new sub-class. Notably, some of these newly discovered miRNAs are generated from untranslated and open reading frames of coding genes, and we experimentally validate these. We also show that many annotated miRNAs do not present miRNA-like features, as they are neither processed by known processing complexes nor loaded on AGO2; this indicates that the current miRNA miRBase database list should be refined and re-defined. Accordingly, a group of them map on ribosomal RNA molecules, whereas others cannot undergo genuine miRNA biogenesis. Notably, a group of annotated miRNAs are Dgcr8 independent and DICER dependent endogenous small interfering RNAs that derive from a unique hairpin formed from a short interspersed nuclear element.

  8. Formation of AlFeSi phase in AlSi12 alloy with Ce addition

    Directory of Open Access Journals (Sweden)

    S. Kores

    2012-04-01

    Full Text Available The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.

  9. Comparison of a T1-weighted inversion-recovery-, gradient-echo- and spin-echo sequence for imaging of the brain at 3.0 Tesla

    International Nuclear Information System (INIS)

    Stehling, C.; Niederstadt, T.; Kraemer, S.; Kugel, H.; Schwindt, W.; Heindel, W.; Bachmann, R.

    2005-01-01

    Purpose: The increased T1 relaxation times at 3.0 Tesla lead to a reduced T1 contrast, requiring adaptation of imaging protocols for high magnetic fields. This prospective study assesses the performance of three techniques for T1-weighted imaging (T1w) at 3.0 T with regard to gray-white differentiation and contrast-to-noise-ratio (CNR). Materials and Methods: Thirty-one patients were examined at a 3.0 T system with axial T1 w inversion recovery (IR), spin-echo (SE) and gradient echo (GE) sequences and after contrast enhancement (CE) with CE-SE and CE-GE sequences. For qualitative analysis, the images were ranked with regard to artifacts, gray-white differentiation, image noise and overall diagnostic quality. For quantitative analysis, the CNR was calculated, and cortex and basal ganglia were compared with the white matter. Results: In the qualitative analysis, IR was judged superior to SE and GE for gray-white differentiation, image noise and overall diagnostic quality, but inferior to the GE sequence with regard to artifacts. CE-GE proved superior to CE-SE in all categories. In the quantitative analysis, CNR of the based ganglia was highest for IR, followed by GE and SE. For the CNR of the cortex, no significant difference was found between IR (16.9) and GE (15.4) but both were superior to the SE (9.4). The CNR of the cortex was significantly higher for CE-GE compared to CE-SE (12.7 vs. 7.6, p<0.001), but the CNR of the basal ganglia was not significantly different. Conclusion: For unenhanced T1w imaging at 3.0 T, the IR technique is, despite increased artifacts, the method of choice due to its superior gray-white differentiation and best overall image quality. For CE-studies, GE sequences are recommended. For cerebral imaging, SE sequences give unsatisfactory results at 3.0 T. (orig.)

  10. SU-E-I-51: Use of Blade Sequences in Cervical Spine MR Imaging for Eliminating Motion, Truncation and Flow Artifacts

    Energy Technology Data Exchange (ETDEWEB)

    Mavroidis, P [University of Texas Health Science Center, UTHSCSA, San Antonio, TX (United States); Lavdas, E; Kostopoulos, S; Ninos, C; Strikou, A; Glotsos, D; Vlachopoulou, A; Oikonomou, G [Technological Education Institute of Athens, Athens, Athens (Greece); Economopoulos, N [General University Hospital ATTIKON, Athens, Athens (Greece); Roka, V [Health Center of Farkadona, Trikala (Greece); Sakkas, G [Center for Research and Technology of Thessaly, Trikala (Greece); Tsagkalis, A; Batsikas, G [IASO Thessalias Hospital, Larissa (Greece); Statkahis, S [Cancer Therapy and Research Center, San Antonio, TX (United States); Papanikolaou, N [University of Texas HSC SA, San Antonio, TX (United States)

    2014-06-01

    Purpose: To assess the efficacy of the BLADE technique to eliminate motion, truncation, flow and other artifacts in Cervical Spine MRI compared to the conventional technique. To study the ability of the examined sequences to reduce the indetention and wrap artifacts, which have been reported in BLADE sagittal sequences. Methods: Forty consecutive subjects, who had been routinely scanned for cervical spine examination using four different image acquisition techniques, were analyzed. More specifically, the following pairs of sequences were compared: a) T2 TSE SAG vs. T2 TSE SAG BLADE and b) T2 TIRM SAG vs. T2 TIRM SAG BLADE. A quantitative analysis was performed using the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and relative contrast (ReCon) measures. A qualitative analysis was also performed by two radiologists, who graded seven image characteristics on a 5-point scale (0:non-visualization; 1:poor; 2:average; 3:good; 4:excellent). The observers also evaluated the presence of image artifacts (motion, truncation, flow, indentation). Results: Based on the findings of the quantitative analysis, the ReCON values of the CSF (cerebrospinal fluid)/SC (spinal cord) between TIRM SAG and TIRM SAG BLADE were found to present statistical significant differences (p<0.001). Regarding motion and truncation artifacts, the T2 TSE SAG BLADE was superior compared to the T2 TSE SAG and the T2 TIRM SAG BLADE was superior compared to the T2 TIRM SAG. Regarding flow artifacts, T2 TIRM SAG BLADE eliminated more artifacts compared to the T2 TIRM SAG. Conclusion: The use of BLADE sequences in cervical spine MR examinations appears to be capable of potentially eliminating motion, pulsatile flow and trancation artifacts. Furthermore, BLADE sequences are proposed to be used in the standard examination protocols based on the fact that a significantly improved image quality could be achieved.

  11. SU-E-I-51: Use of Blade Sequences in Cervical Spine MR Imaging for Eliminating Motion, Truncation and Flow Artifacts

    International Nuclear Information System (INIS)

    Mavroidis, P; Lavdas, E; Kostopoulos, S; Ninos, C; Strikou, A; Glotsos, D; Vlachopoulou, A; Oikonomou, G; Economopoulos, N; Roka, V; Sakkas, G; Tsagkalis, A; Batsikas, G; Statkahis, S; Papanikolaou, N

    2014-01-01

    Purpose: To assess the efficacy of the BLADE technique to eliminate motion, truncation, flow and other artifacts in Cervical Spine MRI compared to the conventional technique. To study the ability of the examined sequences to reduce the indetention and wrap artifacts, which have been reported in BLADE sagittal sequences. Methods: Forty consecutive subjects, who had been routinely scanned for cervical spine examination using four different image acquisition techniques, were analyzed. More specifically, the following pairs of sequences were compared: a) T2 TSE SAG vs. T2 TSE SAG BLADE and b) T2 TIRM SAG vs. T2 TIRM SAG BLADE. A quantitative analysis was performed using the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and relative contrast (ReCon) measures. A qualitative analysis was also performed by two radiologists, who graded seven image characteristics on a 5-point scale (0:non-visualization; 1:poor; 2:average; 3:good; 4:excellent). The observers also evaluated the presence of image artifacts (motion, truncation, flow, indentation). Results: Based on the findings of the quantitative analysis, the ReCON values of the CSF (cerebrospinal fluid)/SC (spinal cord) between TIRM SAG and TIRM SAG BLADE were found to present statistical significant differences (p<0.001). Regarding motion and truncation artifacts, the T2 TSE SAG BLADE was superior compared to the T2 TSE SAG and the T2 TIRM SAG BLADE was superior compared to the T2 TIRM SAG. Regarding flow artifacts, T2 TIRM SAG BLADE eliminated more artifacts compared to the T2 TIRM SAG. Conclusion: The use of BLADE sequences in cervical spine MR examinations appears to be capable of potentially eliminating motion, pulsatile flow and trancation artifacts. Furthermore, BLADE sequences are proposed to be used in the standard examination protocols based on the fact that a significantly improved image quality could be achieved

  12. Electrochemical characteristics of nc-Si/SiC composite for anode electrode of lithium ion batteries

    International Nuclear Information System (INIS)

    Jeon, Bup Ju; Lee, Joong Kee

    2014-01-01

    Graphical abstract: Cycling performances and coulombic efficiencies of the nc-Si/SiC composite anodes at different CH 4 /SiH 4 mole ratios. -- Highlights: • Our work has focused on irreversible discharge capacity and capacity retention of nc-Si/SiC composite particles. • Particles comprised a mixed construction of nc-Si/SiC structure with dual phases. • The SiC phase acted as retarding media, leading to enhanced cycle stability. -- Abstract: nc-Si/SiC composite particles were prepared as an anode material for lithium ion batteries using a plasma jet with DC arc discharge. The composition of the nc-Si/SiC composite particles was controlled by setting the mole ratio of CH 4 and SiH 4 precursor gases. X-ray diffraction, TEM images, and Raman shift analyses revealed that the synthesized nc-Si/SiC composite particles comprised a construction of nano-nocaled structure with crystalline phases of active silicon, highly disordered amorphous carbon of graphite and crystalline phases of β-SiC. In the experimental range examined, the nc-Si/SiC composite particles showed good coulombic efficiency in comparison with particles high Si–Si bonding content due to the interplay of particles with a small proportion of carbon and the buffering effect against volume expansion by structural stabilization, and played a role as retarding media for the rapid electrochemical reactions of the SiC crystal against lithium

  13. Electrochemical characteristics of nc-Si/SiC composite for anode electrode of lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Bup Ju [Department of Energy Resources, Shinhan University, 233-1, Sangpae-dong, Dongducheon, Gyeonggi-do, 483-777 (Korea, Republic of); Lee, Joong Kee, E-mail: leejk@kist.re.kr [Advanced Energy Materials Processing Laboratory, Center for Energy Convergence Research, Green City Technology Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

    2014-03-25

    Graphical abstract: Cycling performances and coulombic efficiencies of the nc-Si/SiC composite anodes at different CH{sub 4}/SiH{sub 4} mole ratios. -- Highlights: • Our work has focused on irreversible discharge capacity and capacity retention of nc-Si/SiC composite particles. • Particles comprised a mixed construction of nc-Si/SiC structure with dual phases. • The SiC phase acted as retarding media, leading to enhanced cycle stability. -- Abstract: nc-Si/SiC composite particles were prepared as an anode material for lithium ion batteries using a plasma jet with DC arc discharge. The composition of the nc-Si/SiC composite particles was controlled by setting the mole ratio of CH{sub 4} and SiH{sub 4} precursor gases. X-ray diffraction, TEM images, and Raman shift analyses revealed that the synthesized nc-Si/SiC composite particles comprised a construction of nano-nocaled structure with crystalline phases of active silicon, highly disordered amorphous carbon of graphite and crystalline phases of β-SiC. In the experimental range examined, the nc-Si/SiC composite particles showed good coulombic efficiency in comparison with particles high Si–Si bonding content due to the interplay of particles with a small proportion of carbon and the buffering effect against volume expansion by structural stabilization, and played a role as retarding media for the rapid electrochemical reactions of the SiC crystal against lithium.

  14. Diagnostic performance of the three-dimensional fast spin echo-Cube sequence in comparison with a conventional imaging protocol in evaluation of the lachrymal drainage system

    International Nuclear Information System (INIS)

    Zhang, Jing; Chen, Lang; Wang, Qiu-Xia; Zhu, Wen-Zhen; Luo, Xin; Peng, Li; Liu, Rong; Xiong, Wei

    2015-01-01

    To compare the three-dimensional (3D)-fast spin-echo (FSE)-Cube with a conventional imaging protocol in evaluation of dacryostenosis. Thirty-three patients with epiphora underwent examinations using Cube magnetic resonance dacryocystography (MRD) and a conventional protocol, which included 3D fast-recovery fast spin-echo (FRFSE) MRD and two-dimensional (2D)-FSE sequences at 3.0 T. Using lachrymal endoscopic findings as the reference standard, we calculated the sensitivity and specificity of both protocols for detecting lachrymal drainage system (LDS) obstruction and their accuracies in depicting the level of obstruction. Comparable coronal and axial images were selected for bot sequences. Two neuroradiologists graded paired images for blurring, artefacts, anatomic details, and overall image quality. The two methods showed no significant difference in sensitivity (89.5 % vs. 94.7 %; p =0.674), specificity (64.3 %; p =1) or accuracy (86.8 %; p =1) in detecting or depicting LDS obstruction. Blurring and artefacts were significantly better on 2D-FSE images (p 0.05). In comparison with the conventional protocol, Cube MRD demonstrates satisfactory image quality and similar diagnostic capability for cases of possible LDS disease. (orig.)

  15. Preliminary timing measurements on a data acquisition chain for a SiPM-based detector for prostate imaging

    Science.gov (United States)

    Gabrielli, A.; Antonioli, P.; D'Antone, I.; Giorgi, F. M.; Lax, I.; Lolli, M.; De Leo, R.; De Robertis, G.; Foresta, M.; Loddo, F.; Ranieri, A.; Cosentino, G.; Finocchiaro, P.; Pappalardo, A. D.; Fonte, R.; Calvini, C.; Musico, P.; Ottonello, P.; Cusanno, F.; Garibaldi, F.; Gigli, T.; Giove, F.; Maraviglia, B.; Meddi, F.; Rivetti, A.

    2011-06-01

    Prostate cancer (PC) is one of the most common diseases in western countries and a leading cause of cancer death. A variety of treatment options are available but a precise disease characterization is needed: evaluation of cancer location, size, and extent and an indication of tumor aggressiveness. The current standard for diagnosing PC is transrectal ultrasound guided sextant biopsy. A novel multidisciplinary approach is required. Imaging may play a key role provided that dedicated prostate imagers and procedures are available: considerable improvements have been achieved in diagnosis with the Magnetic Resonance Imaging (MRI) and nuclear medicine (Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT)) techniques. Nevertheless, due to sub-optimal prostate imaging geometries with these generic large instruments preventing separation of the signal from surrounding organs, the sensitivity, spatial resolution and lesion contrast detected are lower compared to what can be potentially achievable with optimized dedicated prostate imagers and procedures. Fully exploiting the Time Of Flight (TOF) capability would allow not only to increase the Signal-to-Noise ratio (SNR) / Noise Equivalent Count Rate (NECR) but also to get rid of the huge background coming from neighboring organs i.e. the bladder. Recently a new research project was initiated by a large INFN collaboration, and a "TOF-PET and MRI for prostate cancer diagnosis and follow up experiment" (TOPEM) was financed as a 3-year experiment by the Italian "INFN Commissione Scientifica Nazionale V" with the goal of designing, building and testing in phantom tests an endorectal PET-TOF probe compatible with MRI.

  16. Magnetic Resonance Cholangiopancreatography: Image Quality, Ductal Morphology, and Value of Additional T2- and T1-weighted Sequences for the Assessment of Suspected Pancreatic Cancer

    International Nuclear Information System (INIS)

    Lopez Haenninen, E.; Ricke, H.; Amthauer, H.; Roettgen, R.; Boehmig, M.; Langrehr, J.; Pech, M.; Denecke, T.; Rosewicz, S.; Felix, R.

    2005-01-01

    Purpose: To assess image quality and duct morphology on magnetic resonance cholangiopancreatography (MRCP) and also the value of additional T2- and T1-weighted sequences for differentiation of benignity and malignancy in patients with suspected pancreatic tumors. Material and Methods: One-hundred-and-fourteen patients received MRCP and unenhanced and contrast material-enhanced MR imaging. MR results were analyzed independently by two blinded readers, and subsequently correlated with the results from surgery, biopsy, and follow-up. Assessment included the evaluation of image quality, duct visualization and morphology, and the differentiation of pancreatic lesion status (benign versus malignant).Results: Overall, 49 patients had benign final diagnoses, while 65 had a malignant diagnosis. Image quality of single-shot thick-slab MRCP was rated significantly better than the MIP images of multisection MRCP. With MRCP alone, the two readers' accuracy in the assessment of pancreatic lesion status was 72% (95% CI, 64% to 83%) and 69% (95% CI, 56% to 77%), respectively; with the addition of T2- and T1-weighted images the accuracy significantly improved to 89% (95% CI, 82% to 95%) and 84% (95% CI, 77% to 92%) for readers 1 and 2, respectively. Conclusion: Single-shot thick-slab MRCP and multisection MRCP provide complementary results; however, single-shot MRCP had superior image quality. Moreover, assessment of ductal morphology with MRCP alone facilitated the diagnosis of different pathologic conditions of the pancreatobiliary system in the majority of patients. However, with the addition of T2- and T1-weighted sequences the overall diagnostic accuracy was significantly improved and thus we consider that a comprehensive MR approach should comprise both MRCP techniques and parenchymal sequences

  17. Liver imaging at 3.0 T: Diffusion-induced black-blood echo-planar imaging with large anatomic volumetric coverage as an alternative for specific absorption rate-intensive echo-train spin-echo sequences: Feasibility study

    NARCIS (Netherlands)

    I.C. van den Bos (Indra); S.M. Hussain (Shahid); G.P. Krestin (Gabriel); P.A. Wielopolski (Piotr)

    2008-01-01

    textabstractInstitutional Review Board approval and signed informed consent were obtained by all participants for an ongoing sequence optimization project at 3.0 T. The purpose of this study was to evaluate breath-hold diffusion-induced blackblood echo-planar imaging (BBEPI) as a potential

  18. SI Notes.

    Science.gov (United States)

    Nelson, Robert A.

    1983-01-01

    Discusses legislation related to SI (International Systems of Units) in the United States. Indicates that although SI metric units have been officially recognized by law in the United States, U.S. Customary Units have never received a statutory basis. (JN)

  19. THERMAL IMAGING OF Si, GaAs AND GaN -BASED DEVICES WITHIN THE MICROTHERM PROJECT

    OpenAIRE

    Pavageau , S.; Tessier , G.; Filloy , C.; Jerosolimski , G.; Fournier , D.; Polignano , M.-L.; Mica , I.; Cassette , S.; Aubry , R.; Durand , O.

    2005-01-01

    Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/5920); International audience; Within the european project Microtherm, we have developed a CCD-based thermoreflectance system which delivers thermal images of working integrated circuits with high spatial and thermal resolutions (down to 350 nm and 0.1 K respectively). We illustrate the performances of this set-up on several classes of semiconductor devices including high power transistors and transistor ar...

  20. PINPIN a-Si:H based structures for X-ray image detection using the laser scanning technique

    Science.gov (United States)

    Fernandes, M.; Vygranenko, Y.; Vieira, M.

    2015-05-01

    Conventional film based X-ray imaging systems are being replaced by their digital equivalents. Different approaches are being followed by considering direct or indirect conversion, with the later technique dominating. The typical, indirect conversion, X-ray panel detector uses a phosphor for X-ray conversion coupled to a large area array of amorphous silicon based optical sensors and a couple of switching thin film transistors (TFT). The pixel information can then be readout by switching the correspondent line and column transistors, routing the signal to an external amplifier. In this work we follow an alternative approach, where the electrical switching performed by the TFT is replaced by optical scanning using a low power laser beam and a sensing/switching PINPIN structure, thus resulting in a simpler device. The optically active device is a PINPIN array, sharing both front and back electrical contacts, deposited over a glass substrate. During X-ray exposure, each sensing side photodiode collects photons generated by the scintillator screen (560 nm), charging its internal capacitance. Subsequently a laser beam (445 nm) scans the switching diodes (back side) retrieving the stored charge in a sequential way, reconstructing the image. In this paper we present recent work on the optoelectronic characterization of the PINPIN structure to be incorporated in the X-ray image sensor. The results from the optoelectronic characterization of the device and the dependence on scanning beam parameters are presented and discussed. Preliminary results of line scans are also presented.

  1. Using fluence separation to account for energy spectra dependence in computing dosimetric a-Si EPID images for IMRT fields

    International Nuclear Information System (INIS)

    Li Weidong; Siebers, Jeffrey V.; Moore, Joseph A.

    2006-01-01

    This study develops a method to improve the dosimetric accuracy of computed images for an amorphous silicon flat-panel imager. Radially dependent kernels derived from Monte Carlo simulations are convolved with the treatment-planning system's energy fluence. Multileaf collimator (MLC) beam hardening is accounted for by having separate kernels for open and blocked portions of MLC fields. Field-size-dependent output factors are used to account for the field-size dependence of scatter within the imager. Gamma analysis was used to evaluate open and sliding window test fields and intensity modulated patient fields. For each tested field, at least 99.6% of the points had γ<1 with a 3%, 3-mm criteria. With a 2%, 2-mm criteria, between 81% and 100% of points had γ<1. Patient intensity modulated test fields had 94%-100% of the points with γ<1 with a 2%, 2-mm criteria for all six fields tested. This study demonstrates that including the dependencies of kernel and fluence on radius and beam hardening in the convolution improves its accuracy compared with the use of radial and beam-hardening independent kernels; it also demonstrates that the resultant accuracy of the convolution method is sufficient for pretreatment, intensity modulated patient field verification

  2. VLBA imaging of the 3 mm SiO maser emission in the disk-wind from the massive protostellar system Orion Source I

    Science.gov (United States)

    Issaoun, S.; Goddi, C.; Matthews, L. D.; Greenhill, L. J.; Gray, M. D.; Humphreys, E. M. L.; Chandler, C. J.; Krumholz, M.; Falcke, H.

    2017-10-01

    Context. High-mass star formation remains poorly understood due to observational difficulties (e.g. high dust extinction and large distances) hindering the resolution of disk-accretion and outflow-launching regions. Aims: Orion Source I is the closest known massive young stellar object (YSO) and exceptionally powers vibrationally-excited SiO masers at radii within 100 AU, providing a unique probe of gas dynamics and energetics. We seek to observe and image these masers with Very Long Baseline Interferometry (VLBI). Methods: We present the first images of the 28SiO v = 1, J = 2-1 maser emission around Orion Source I observed at 86 GHz (λ3 mm) with the Very Long Baseline Array (VLBA). These images have high spatial ( 0.3 mas) and spectral ( 0.054 km s-1) resolutions. Results: We find that the λ3 mm masers lie in an X-shaped locus consisting of four arms, with blue-shifted emission in the south and east arms and red-shifted emission in the north and west arms. Comparisons with previous images of the 28SiO v = 1,2, J = 1-0 transitions at λ7 mm (observed in 2001-2002) show that the bulk of the J = 2-1 transition emission follows the streamlines of the J = 1-0 emission and exhibits an overall velocity gradient consistent with the gradient at λ7 mm. While there is spatial overlap between the λ3 mm and λ7 mm transitions, the λ3 mm emission, on average, lies at larger projected distances from Source I ( 44 AU compared with 35 AU for λ7 mm). The spatial overlap between the v = 1, J = 1-0 and J = 2-1 transitions is suggestive of a range of temperatures and densities where physical conditions are favorable for both transitions of a same vibrational state. However, the observed spatial offset between the bulk of emission at λ3 mm and λ7 mm possibly indicates different ranges of temperatures and densities for optimal excitation of the masers. We discuss different maser pumping models that may explain the observed offset. Conclusions: We interpret the λ3 mm and λ7 mm

  3. Comparative Analysis of Signal Intensity and Apparent Diffusion Coefficient at Varying b-values in the Brain : Diffusion Weighted-Echo Planar Image (T{sub 2} and FLAIR) Sequence

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jong Kap [Dept. of Radiology, Cheomdan Medical Center, Gwangju (Korea, Republic of); Im, Jung Yeol [Dept. of Digital Management Information Graduate School of Nambu Univesity, Gwangju (Korea, Republic of)

    2009-09-15

    Diffusion-weighted imaging (DWI) has been demonstrated to be a practical method for the diagnosis of various brain diseases such as acute infarction, brain tumor, and white matter disease. In this study, we used two techniques to examine the average signal intensity (SI) and apparent diffusion coefficient (ADC) of the brains of patients who ranged in age from 10 to 60 years. Our results indicated that the average SI was the highest in amygdala (as derived from DWI), whereas that in the cerebrospinal fluid was the lowest. The average ADC was the highest in the cerebrospinal fluid, whereas the lowest measurement was derived from the pons. The average SI and ADC were higher in T{sub 2}-DW-EPI than in FLAIR-DW-EPI. The higher the b-value, the smaller the average difference in both imaging techniques; the lower the b-value, the greater the average difference. Also, comparative analysis of the brains of patients who had experienced cerebral infarction showed no distinct lesion in the general MR image over time. However, there was a high SI in apparent weighted images. Analysis of other brain diseases (e.g., bleeding, acute, subacute, chronic infarction) indicated SI variance in accordance with characteristics of the two techniques. The higher the SI, the lower the ADC. Taken together, the value of SI and ADC in accordance with frequently occurring areas and various brain disease varies based on the b-value and imaging technique. Because they provide additional useful information in the diagnosis and treatment of patients with various brain diseases through signal recognition, the proper imaging technique and b-value are important for the detection and interpretation of subacute stroke and other brain diseases.

  4. Encoding and recall of finger sequences in experienced pianists compared with musically naïve controls: a combined behavioral and functional imaging study.

    Science.gov (United States)

    Pau, S; Jahn, G; Sakreida, K; Domin, M; Lotze, M

    2013-01-01

    Long-term intensive sensorimotor training alters functional representation of the motor and sensory system and might even result in structural changes. However, there is not much knowledge about how previous training impacts learning transfer and functional representation. We tested 14 amateur pianists and 15 musically naïve participants in a short-term finger sequence training procedure, differing considerably from piano playing and measured associated functional representation with functional magnetic resonance imaging. The conditions consisted of encoding a finger sequence indicated by hand symbols ("sequence encoding") and subsequently replaying the sequence from memory, both with and without auditory feedback ("sequence retrieval"). Piano players activated motor areas and the mirror neuron system more strongly than musically naïve participants during encoding. When retrieving the sequence, musically naïve participants showed higher activation in similar brain areas. Thus, retrieval activations of naïve participants were comparable to encoding activations of piano players, who during retrieval performed the sequences more accurately despite lower motor activations. Interestingly, both groups showed primary auditory activation even during sequence retrieval without auditory feedback, supporting previous reports about coactivation of the auditory cortex after learned association with motor performance. When playing with auditory feedback, only pianists lateralized to the left auditory cortex. During encoding activation in left primary somatosensory cortex in the height of the finger representations had a predictive value for increased motor performance later on (error rates). Contrarily, decreased performance was associated with increased visual cortex activation during encoding. Our study extends previous reports about training transfer of motor knowledge resulting in superior training effects in musicians. Performance increase went along with activity in

  5. The OMERACT psoriatic arthritis magnetic resonance imaging scoring system (PsAMRIS): definitions of key pathologies, suggested MRI sequences, and preliminary scoring system for PsA Hands

    DEFF Research Database (Denmark)

    Østergaard, Mikkel; McQueen, Fiona; Wiell, Charlotte

    2009-01-01

    This article describes a preliminary OMERACT psoriatic arthritis magnetic resonance image scoring system (PsAMRIS) for evaluation of inflammatory and destructive changes in PsA hands, which was developed by the international OMERACT MRI in inflammatory arthritis group. MRI definitions of important...... pathologies in peripheral PsA and suggestions concerning appropriate MRI sequences for use in PsA hands are also provided....

  6. Modelling estimation and analysis of dynamic processes from image sequences using temporal random closed sets and point processes with application to the cell exocytosis and endocytosis

    OpenAIRE

    Díaz Fernández, Ester

    2010-01-01

    In this thesis, new models and methodologies are introduced for the analysis of dynamic processes characterized by image sequences with spatial temporal overlapping. The spatial temporal overlapping exists in many natural phenomena and should be addressed properly in several Science disciplines such as Microscopy, Material Sciences, Biology, Geostatistics or Communication Networks. This work is related to the Point Process and Random Closed Set theories, within Stochastic Ge...

  7. MR imaging of hyaline cartilage at 0.5 T: a quantitative and qualitative in vitro evaluation of three types of sequences

    International Nuclear Information System (INIS)

    Linden, E. van der; Kroon, H.M.; Doornbos, J.; Bloem, J.L.; Hermans, J.

    1998-01-01

    Objective. To identify an optimal pulse sequence for in vitro imaging of hyaline cartilage at 0.5 T. Materials and methods. Twelve holes of varying diameter and depth were drilled in cartilage of two pig knees. These were submerged in saline and scanned with a 0.5-T MR system. Sixteen T1-weighted gradient echo (GE), two T2-weighted GE, and 16 fast spin echo sequences were used, by varying repetition time (TR), echo time (TE), flip angle (FA), echo train length, profile order, and by use of fat saturation. Contrast-to-noise ratios (CNR) of cartilage versus saline solution and cartilage versus subchondral bone were measured. Cartilaginous lesions were evaluated separately by three independent observers. Interobserver variability and correlation between the quantitative and qualitative analyses were calculated. Results. The mean CNRs of two specimens of cartilage versus saline solution ranged from 6.3 (±2.1) to 27.7 (±2.5), and those of cartilage versus subchondral bone from 0.3 (±0.2) to 22.5 (±1.4). The highest CNR was obtained with a T1-weighted spoiled 3D-GE technique (TR 65 ms, TE 11.5 ms, FA 45 ). The number of lesions observed per sequence varied from 35 to 69. Observer agreement was fair to good. The T1-weighted spoiled GE sequences with a TR of 65 ms, TE of 11.5 ms and FA of 30 and 45 were significantly superior to the other 34 sequences in the qualitative analysis. Conclusion. T1-weighted spoiled 3D-GE sequences with a TR of 65 ms, a TE of 11.5 ms, and a FA of 30-45 were found to be optimal for in vitro imaging of cartilage at 0.5 T. (orig.)

  8. MR imaging of hyaline cartilage at 0.5 T: a quantitative and qualitative in vitro evaluation of three types of sequences

    Energy Technology Data Exchange (ETDEWEB)

    Linden, E. van der; Kroon, H.M.; Doornbos, J.; Bloem, J.L. [Department of Radiology C2-S, Albinusdreef 2, Leiden University Medical Center, Postbus 9600, NL-2300 RC Leiden (Netherlands); Hermans, J. [Department of Medical Statistics, Leiden University Medical Center, Leiden (Netherlands)

    1998-06-01

    Objective. To identify an optimal pulse sequence for in vitro imaging of hyaline cartilage at 0.5 T. Materials and methods. Twelve holes of varying diameter and depth were drilled in cartilage of two pig knees. These were submerged in saline and scanned with a 0.5-T MR system. Sixteen T1-weighted gradient echo (GE), two T2-weighted GE, and 16 fast spin echo sequences were used, by varying repetition time (TR), echo time (TE), flip angle (FA), echo train length, profile order, and by use of fat saturation. Contrast-to-noise ratios (CNR) of cartilage versus saline solution and cartilage versus subchondral bone were measured. Cartilaginous lesions were evaluated separately by three independent observers. Interobserver variability and correlation between the quantitative and qualitative analyses were calculated. Results. The mean CNRs of two specimens of cartilage versus saline solution ranged from 6.3 ({+-}2.1) to 27.7 ({+-}2.5), and those of cartilage versus subchondral bone from 0.3 ({+-}0.2) to 22.5 ({+-}1.4). The highest CNR was obtained with a T1-weighted spoiled 3D-GE technique (TR 65 ms, TE 11.5 ms, FA 45 ). The number of lesions observed per sequence varied from 35 to 69. Observer agreement was fair to good. The T1-weighted spoiled GE sequences with a TR of 65 ms, TE of 11.5 ms and FA of 30 and 45 were significantly superior to the other 34 sequences in the qualitative analysis. Conclusion. T1-weighted spoiled 3D-GE sequences with a TR of 65 ms, a TE of 11.5 ms, and a FA of 30-45 were found to be optimal for in vitro imaging of cartilage at 0.5 T. (orig.) With 8 figs., 1 tab., 31 refs.

  9. Technical innovation in dynamic contrast-enhanced magnetic resonance imaging of musculoskeletal tumors: an MR angiographic sequence using a sparse k-space sampling strategy.

    Science.gov (United States)

    Fayad, Laura M; Mugera, Charles; Soldatos, Theodoros; Flammang, Aaron; del Grande, Filippo

    2013-07-01

    We demonstrate the clinical use of an MR angiography sequence performed with sparse k-space sampling (MRA), as a method for dynamic contrast-enhanced (DCE)-MRI, and apply it to the assessment of sarcomas for treatment response. Three subjects with sarcomas (2 with osteosarcoma, 1 with high-grade soft tissue sarcomas) underwent MRI after neoadjuvant therapy/prior to surgery, with conventional MRI (T1-weighted, fluid-sensitive, static post-contrast T1-weighted sequences) and DCE-MRI (MRA, time resolution = 7-10 s, TR/TE 2.4/0.9 ms, FOV 40 cm(2)). Images were reviewed by two observers in consensus who recorded image quality (1 = diagnostic, no significant artifacts, 2 = diagnostic, 75 % with good response, >75 % with poor response). DCE-MRI findings were concordant with histological response (arterial enhancement with poor response, no arterial enhancement with good response). Unlike conventional DCE-MRI sequences, an MRA sequence with sparse k-space sampling is easily integrated into a routine musculoskeletal tumor MRI protocol, with high diagnostic quality. In this preliminary work, tumor enhancement characteristics by DCE-MRI were used to assess treatment response.

  10. Technical innovation in dynamic contrast-enhanced magnetic resonance imaging of musculoskeletal tumors: an MR angiographic sequence using a sparse k-space sampling strategy

    International Nuclear Information System (INIS)

    Fayad, Laura M.; Mugera, Charles; Grande, Filippo del; Soldatos, Theodoros; Flammang, Aaron

    2013-01-01

    We demonstrate the clinical use of an MR angiography sequence performed with sparse k-space sampling (MRA), as a method for dynamic contrast-enhanced (DCE)-MRI, and apply it to the assessment of sarcomas for treatment response. Three subjects with sarcomas (2 with osteosarcoma, 1 with high-grade soft tissue sarcomas) underwent MRI after neoadjuvant therapy/prior to surgery, with conventional MRI (T1-weighted, fluid-sensitive, static post-contrast T1-weighted sequences) and DCE-MRI (MRA, time resolution = 7-10 s, TR/TE 2.4/0.9 ms, FOV 40 cm 2 ). Images were reviewed by two observers in consensus who recorded image quality (1 = diagnostic, no significant artifacts, 2 = diagnostic, 75 % with good response, >75 % with poor response). DCE-MRI findings were concordant with histological response (arterial enhancement with poor response, no arterial enhancement with good response). Unlike conventional DCE-MRI sequences, an MRA sequence with sparse k-space sampling is easily integrated into a routine musculoskeletal tumor MRI protocol, with high diagnostic quality. In this preliminary work, tumor enhancement characteristics by DCE-MRI were used to assess treatment response. (orig.)

  11. Nonuniform multiview color texture mapping of image sequence and three-dimensional model for faded cultural relics with sift feature points

    Science.gov (United States)

    Li, Na; Gong, Xingyu; Li, Hongan; Jia, Pengtao

    2018-01-01

    For faded relics, such as Terracotta Army, the 2D-3D registration between an optical camera and point cloud model is an important part for color texture reconstruction and further applications. This paper proposes a nonuniform multiview color texture mapping for the image sequence and the three-dimensional (3D) model of point cloud collected by Handyscan3D. We first introduce nonuniform multiview calibration, including the explanation of its algorithm principle and the analysis of its advantages. We then establish transformation equations based on sift feature points for the multiview image sequence. At the same time, the selection of nonuniform multiview sift feature points is introduced in detail. Finally, the solving process of the collinear equations based on multiview perspective projection is given with three steps and the flowchart. In the experiment, this method is applied to the color reconstruction of the kneeling figurine, Tangsancai lady, and general figurine. These results demonstrate that the proposed method provides an effective support for the color reconstruction of the faded cultural relics and be able to improve the accuracy of 2D-3D registration between the image sequence and the point cloud model.

  12. SU-E-J-223: A BOLD Contrast Imaging Sequence to Evaluate Oxygenation Changes Due to Breath Holding for Breast Radiotherapy: A Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, J; Chang, Z; Cai, J; Palta, M; Horton, J; Yin, F; Blitzblau, R [Duke University Medical Center, Durham, NC (United States)

    2015-06-15

    Purpose: To develop a robust MRI sequence to measure BOLD breath hold induced contrast in context of breast radiotherapy. Methods: Two sequences were selected from prior studies as candidates to measure BOLD contrast attributable to breath holding within the breast: (1) T2* based Gradient Echo EPI (TR/TE = 500/41ms, flip angle = 60°), and (2) T2 based Single Shot Fast Spin Echo (SSFSE) (TR/TE = 3000/60ms). We enrolled ten women post-lumpectomy for breast cancer who were undergoing treatment planning for whole breast radiotherapy. Each session utilized a 1.5T GE MRI and 4 channel breast coil with the subject immobilized prone on a custom board. For each sequence, 1–3 planes of the lumpectomy breast were imaged continuously during a background measurement (1min) and intermittent breath holds (20–40s per breath hold, 3–5 holds per sequence). BOLD contrast was quantified as correlation of changes in per-pixel intensity with the breath hold schedule convolved with a hemodynamic response function. Subtle motion was corrected using a deformable registration algorithm. Correlation with breath-holding was considered significant if p<0.001. Results: The percentage of the breast ROI with positive BOLD contrast measured by the two sequences were in agreement with a correlation coefficient of R=0.72 (p=0.02). While both sequences demonstrated areas with strong BOLD response, the response was more systematic throughout the breast for the SSFSE (T2) sequence (% breast with response in the same direction: 51.2%±0.7% for T2* vs. 68.1%±16% for T2). In addition, the T2 sequence was less prone to magnetic susceptibility artifacts, especially in presence of seroma, and provided a more robust image with little distortion or artifacts. Conclusion: A T2 SSFSE sequence shows promise for measuring BOLD contrast in the context of breast radiotherapy utilizing a breath hold technique. Further study in a larger patient cohort is warranted to better refine this novel technique.

  13. SU-E-J-223: A BOLD Contrast Imaging Sequence to Evaluate Oxygenation Changes Due to Breath Holding for Breast Radiotherapy: A Pilot Study

    International Nuclear Information System (INIS)

    Adamson, J; Chang, Z; Cai, J; Palta, M; Horton, J; Yin, F; Blitzblau, R

    2015-01-01

    Purpose: To develop a robust MRI sequence to measure BOLD breath hold induced contrast in context of breast radiotherapy. Methods: Two sequences were selected from prior studies as candidates to measure BOLD contrast attributable to breath holding within the breast: (1) T2* based Gradient Echo EPI (TR/TE = 500/41ms, flip angle = 60°), and (2) T2 based Single Shot Fast Spin Echo (SSFSE) (TR/TE = 3000/60ms). We enrolled ten women post-lumpectomy for breast cancer who were undergoing treatment planning for whole breast radiotherapy. Each session utilized a 1.5T GE MRI and 4 channel breast coil with the subject immobilized prone on a custom board. For each sequence, 1–3 planes of the lumpectomy breast were imaged continuously during a background measurement (1min) and intermittent breath holds (20–40s per breath hold, 3–5 holds per sequence). BOLD contrast was quantified as correlation of changes in per-pixel intensity with the breath hold schedule convolved with a hemodynamic response function. Subtle motion was corrected using a deformable registration algorithm. Correlation with breath-holding was considered significant if p<0.001. Results: The percentage of the breast ROI with positive BOLD contrast measured by the two sequences were in agreement with a correlation coefficient of R=0.72 (p=0.02). While both sequences demonstrated areas with strong BOLD response, the response was more systematic throughout the breast for the SSFSE (T2) sequence (% breast with response in the same direction: 51.2%±0.7% for T2* vs. 68.1%±16% for T2). In addition, the T2 sequence was less prone to magnetic susceptibility artifacts, especially in presence of seroma, and provided a more robust image with little distortion or artifacts. Conclusion: A T2 SSFSE sequence shows promise for measuring BOLD contrast in the context of breast radiotherapy utilizing a breath hold technique. Further study in a larger patient cohort is warranted to better refine this novel technique

  14. MR imaging of mediastinal foregut cysts

    International Nuclear Information System (INIS)

    LeBlanc, J.; Guttentag, A.R.; McLoud, T.C.; Shepard, J.O.

    1991-01-01

    This paper reports on the diagnosis of mediastinal foregut cysts which are difficult to establish even with CT, because these lesions often have high attenuation numbers similar to tumors. This study was undertaken to determine the value of MR imaging in the diagnosis of foregut cysts. MR imaging of 58 mediastinal masses was performed between 1986 and 1991 at 0.5 T, with T1- and T2-weighted images obtained. Seven foregut cysts were identified. Five were pathologically proven; in two cases the diagnosis was based on clinical findings and radiologic stability. Signal characteristics were compared with those of 52 pathologically proven mediastinal masses: six thymomas, 10 thyroid goiters and carcinomas, 11 neurogenic tumors, 15 lymphomas, and 10 miscellaneous masses. Fat and muscle were used as internal standards of signal intensity (SI). All foregut cysts were very bright on T2-weighted images. On T1-weighted sequences, two had low SI, but the remaining five showed high SI. These differences reflected variability in cyst protein content, high SI indicating the presence of mucus. On T1-weighted images, low SI was identified in most other mediastinal masses, but uniform high SI was specific for foregut cysts. Our series did not include any fatty lesions, as these were easily recognized on CT scans

  15. Same day injections of Tc-99m methoxy isobutyl isonitrile (hexamibi) for myocardial tomographic imaging: Comparison between rest-stress and stress-rest injection sequences

    International Nuclear Information System (INIS)

    Taillefer, R.; Gagnon, A.; Laflamme, L.; Leveille, J.; Phaneuf, D.C.

    1989-01-01

    It has been shown that both rest and stress 99m Tc-hexamibi myocardial perfusion imaging can be performed on the same day using two different doses injected within few h (the first one at rest followed by a second at stress). In order to evaluate and compare 2 sequences (rest-stress and stress-rest) of 99m Tc-hexamibi injections performed the same day, 18 patients with either abnormal 201 Tl myocardial scan or abnormal coronary angiography were studied with 2 99m Tc-hexamibi injections protocols. The rest-stress study was performed as follows: 7 mCi 99m Tc-hexamibi was injected at rest. Single photon emission computed tomography (SPECT) was performed 60 min later. Immediately after the rest study, patients were injected at peak stress with 25 mCi 99m Tc-hexamibi. Tomographic imaging was repeated 1 h later. Patients were submitted to the stress-rest protocol within 3 days. Tomographic imaging was done 1 h after a 7 mCi injection at stress. This study was followed by an injection of 25 mCi 99m Tc-hexamibi at rest, a tomographic study was performed 60 min later. Myocardial sections were reconstructed in horizontal long, vertical long, and short axes. Data analysis also included polar map representation. A total of 324 segments were interpreted blind by 3 observers, there was an agreement in 283/324 (87.3%) segments between the 2 protocols. However, 24 segments (7.4%) judged ischemic on rest-stress were called scars on stress-rest. In three patients, myocardial segments were judged normal on the rest image of the rest-stress protocol while they were found abnormal (false positive images) on the stress-rest sequence. Stress images from both protocols were judged similar in 17 patients. In conclusion, when using a short time interval (less than 2 h) between two 99m Tc-hexamibi injections, it is preferable to do a rest-stress sequence since the rest image performed initially represents a true rest study, which is not necessarily the case with the stress-rest sequence

  16. The role of MR imaging with Half Fourier Acquired Single Shot Turbo Spin Echo sequence in the diagnosis of lung lesions in comparison with multislice CT

    International Nuclear Information System (INIS)

    Hekimoglu, B.; Gurgen, F.; Tatar, I.G.; Aydin, H.; Kizilgoz, V.; Keyik, B.

    2013-01-01

    Objective: To compare the diagnostic values of magnetic resonance imaging using Half Fourier Acquired Single Shot Turbo Spin Echo sequence and multidetector computed tomography in patients with pathologically examined pulmonary lesions. Methods: The retrospective, descriptive study was conducted at Radiology Department, Diskapi Research Hospital, Ankara, Turkey, and comprised records of patients with pathologically examined pulmonary lesions between May 2009 and March 2012. Patients were divided into three groups and examined by both multi dedector computed tomography and magnetic resonance imaging. During the imaging, patients were not administered any intravenous contrast medium. Electrocardiogram gating and breath holding were not performed in echo sequence. Pulmonary lesions were evaluated on the basis of their dimensions, numbers, differentiation from atelectasis and consolidation, invasion to the thoracic wall-mediastinal structures and presence of lymphadenopathies. Results: Sensitivity of all patients was 50% (p=0.214) and specificity of CT and MRI were 82.5% (p=0.134) for the detectability of submilimetric nodules . For differentiation of the mass from atelectasis and consolidation, the sensitivity of computed tomography was statistically more significant compared to magnetic resonance imaging (86.6%; p=0.035). For the invasion of the mass to the mediastinal structures and the thoracic wall, the sensitivity of magnetic resonance imaging was statistically more significant compared to tomography (86.6%; p=0.035). Conclusion: HASTE sequence can be used to determine the invasion of the pulmonary mass to the mediastinal structures and the thoracic wall since it is more sensitive than computed tomography. It can also be used to detect submilimetric nodules. It has equal sensitivity and specificity compared to computed tomography. But computed tomography is superior for the differentiation of the mass from atelectasis and consolidation. (author)

  17. B1 mapping for bias-correction in quantitative T1 imaging of the brain at 3T using standard pulse sequences.

    Science.gov (United States)

    Boudreau, Mathieu; Tardif, Christine L; Stikov, Nikola; Sled, John G; Lee, Wayne; Pike, G Bruce

    2017-12-01

    B 1 mapping is important for many quantitative imaging protocols, particularly those that include whole-brain T 1 mapping using the variable flip angle (VFA) technique. However, B 1 mapping sequences are not typically available on many magnetic resonance imaging (MRI) scanners. The aim of this work was to demonstrate that B 1 mapping implemented using standard scanner product pulse sequences can produce B 1 (and VFA T 1 ) maps comparable in quality and acquisition time to advanced techniques. Six healthy subjects were scanned at 3.0T. An interleaved multislice spin-echo echo planar imaging double-angle (EPI-DA) B 1 mapping protocol, using a standard product pulse sequence, was compared to two alternative methods (actual flip angle imaging, AFI, and Bloch-Siegert shift, BS). Single-slice spin-echo DA B 1 maps were used as a reference for comparison (Ref. DA). VFA flip angles were scaled using each B 1 map prior to fitting T 1 ; the nominal flip angle case was a