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Sample records for enhanced k-edge angiography

  1. K-Edge Subtraction Angiography with Synchrotron X-Rays

    CERN Document Server

    Giacomini, J C

    1996-01-01

    The purpose of this project was to utilize dual energy, monochromatic X-rays produced from synchrotrons radiation in order to obtain noninvasive medical imaging. The application of synchrotrons radiation to medical imaging is based on the principle of iodine dichromography, first described by Bertil Jacobson of the Karolinska Institute in 1953. Medical imaging using synchrotrons radiation and K-edge dichromography was pioneered at Stanford University under the leadership of Dr. Ed Rubenstein, and the late Nobel Laureate in Physics, Dr. Robert Hofstadter. With progressive refinements in hardware, clinical-quality images were obtained of human coronary arteries utilizing peripheral injections of iodinated contrast agent. These images even now are far superior to those being presented by investigators using MRI as an imaging tool for coronary arteries. However, new supplies and instruments in the cardiac catheterization laboratory have served to transform coronary angiography into an outpatient procedure, with r...

  2. K-Edge Subtraction Angiography with Synchrotron X-Rays

    International Nuclear Information System (INIS)

    Giacomini, John C.

    1996-01-01

    The purpose of this project was to utilize dual energy, monochromatic X-rays produced from synchrotrons radiation in order to obtain noninvasive medical imaging. The application of synchrotrons radiation to medical imaging is based on the principle of iodine dichromography, first described by Bertil Jacobson of the Karolinska Institute in 1953. Medical imaging using synchrotrons radiation and K-edge dichromography was pioneered at Stanford University under the leadership of Dr. Ed Rubenstein, and the late Nobel Laureate in Physics, Dr. Robert Hofstadter. With progressive refinements in hardware, clinical-quality images were obtained of human coronary arteries utilizing peripheral injections of iodinated contrast agent. These images even now are far superior to those being presented by investigators using MRI as an imaging tool for coronary arteries. However, new supplies and instruments in the cardiac catheterization laboratory have served to transform coronary angiography into an outpatient procedure, with relatively little morbidity. We extended the principles learned with coronary angiography to noninvasive imaging of the human bronchial tree. For these images, we utilized xenon as the contrast agent, as it has a K-edge very similar to that of iodine. In this case, there is no true competing diagnostic test, and pulmonary neoplasm is an enormous public health concern. In early experiments, we demonstrated remarkably clear images of the human bronchial tree. These images have been shown internationally; however, funding difficulties primarily with the Department of Energy have not allowed for progression of this promising avenue of research. One potential criticism of the project is that in order to obtain these images, we utilized national laboratories. Some have questioned whether this would lead to a practical imaging modality. However, we have shown that the technology exists to allow for construction of a miniature storage ring, with a superconducting

  3. The potential for neurovascular intravenous angiography using K-edge digital subtraction angiography

    International Nuclear Information System (INIS)

    Schueltke, E.; Fiedler, S.; Kelly, M.; Griebel, R.; Juurlink, B.; LeDuc, G.; Esteve, F.; Le Bas, J.-F.; Renier, M.; Nemoz, C.; Meguro, K.

    2005-01-01

    Background: Catheterization of small-caliber blood vessels in the central nervous system can be extremely challenging. Alternatively, intravenous (i.v.) administration of contrast agent is minimally invasive and therefore carries a much lower risk for the patient. With conventional X-ray equipment, volumes of contrast agent that could be safely administered to the patient do not allow acquisition of high-quality images after i.v. injection, because the contrast bolus is extremely diluted by passage through the heart. However, synchrotron-based digital K-edge subtraction angiography does allow acquisition of high-quality images after i.v. administration of relatively small doses of contrast agent. Materials and methods: Eight adult male New Zealand rabbits were used for our experiments. Animals were submitted to both angiography with conventional X-ray equipment and synchrotron-based digital subtraction angiography. Results: With conventional X-ray equipment, no contrast was seen in either cerebral or spinal blood vessels after i.v. injection of iodinated contrast agent. However, using K-edge digital subtraction angiography, as little as 1 ml iodinated contrast agent, when administered as i.v. bolus, yielded images of small-caliber blood vessels in the central nervous system (both brain and spinal cord). Conclusions: If it would be possible to image blood vessels of the same diameter in the central nervous system of human patients, the synchrotron-based technique could yield high-quality images at a significantly lower risk for the patient than conventional X-ray imaging. Images could be acquired where catheterization of feeding blood vessels has proven impossible

  4. Exotic sources of x-rays for iodine K-edge angiography

    International Nuclear Information System (INIS)

    Carr, R.

    1993-08-01

    Digital Subtractive Angiography (DSA) has been performed to image human coronary arteries using wiggler radiation from electron storage rings. The significant medical promise of this procedure motivates the development of smaller and less costly x-ray sources. Several exotic sources are candidates for consideration, using effects such as Cherenkov, channeling, coherent bremsstrahlung, laser backscattering, microundulator, parametric, Smith-Purcell, and transition radiation. In this work we present an analysis of these effects as possible sources of intense x-rays at the iodine K-edge at 33.169 key. The criteria we use are energy, efficiency, flux, optical properties, and technical realizability. For each of the techniques, we find that they suffer either from low flux, a low energy cutoff, target materials heating, too high electron beam energy requirement, optical mismatch to angiography, or a combination of these. We conclude that the foreseeable state-of-the-art favors a compact storage ring design

  5. K-Edge Subtraction Angiography with Synchrotron X-Rays; TOPICAL

    International Nuclear Information System (INIS)

    Giacomini, John C.

    1996-01-01

    The purpose of this project was to utilize dual energy, monochromatic X-rays produced from synchrotrons radiation in order to obtain noninvasive medical imaging. The application of synchrotrons radiation to medical imaging is based on the principle of iodine dichromography, first described by Bertil Jacobson of the Karolinska Institute in 1953. Medical imaging using synchrotrons radiation and K-edge dichromography was pioneered at Stanford University under the leadership of Dr. Ed Rubenstein, and the late Nobel Laureate in Physics, Dr. Robert Hofstadter. With progressive refinements in hardware, clinical-quality images were obtained of human coronary arteries utilizing peripheral injections of iodinated contrast agent. These images even now are far superior to those being presented by investigators using MRI as an imaging tool for coronary arteries. However, new supplies and instruments in the cardiac catheterization laboratory have served to transform coronary angiography into an outpatient procedure, with relatively little morbidity. We extended the principles learned with coronary angiography to noninvasive imaging of the human bronchial tree. For these images, we utilized xenon as the contrast agent, as it has a K-edge very similar to that of iodine. In this case, there is no true competing diagnostic test, and pulmonary neoplasm is an enormous public health concern. In early experiments, we demonstrated remarkably clear images of the human bronchial tree. These images have been shown internationally; however, funding difficulties primarily with the Department of Energy have not allowed for progression of this promising avenue of research. One potential criticism of the project is that in order to obtain these images, we utilized national laboratories. Some have questioned whether this would lead to a practical imaging modality. However, we have shown that the technology exists to allow for construction of a miniature storage ring, with a superconducting

  6. Synchrotron-based intra-venous K-edge digital subtraction angiography in a pig model: A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Schueltke, Elisabeth [Departments of Surgery, University of Saskatchewan, Saskatoon, SK (Canada); Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK (Canada); Department of Neurological Sciences, Walton Medical Centre, University of Liverpool, Liverpool L97 LJ (United Kingdom)], E-mail: e.schultke@usask.ca; Fiedler, Stefan [European Molecular Biology Laboratory (EMBL), Nottkestrasse 85, 22603 Hamburg (Germany); Nemoz, Christian [European Synchrotron Radiation Facility (ESRF), 6 rue Horowitz, 38043 Grenoble (France); Ogieglo, Lissa [Departments of Surgery, University of Saskatchewan, Saskatoon, SK (Canada); Kelly, Michael E. [Departments of Surgery, University of Saskatchewan, Saskatoon, SK (Canada); Department of Neurosurgery, Section of Cerebrovascular and Endovascular Neurosurgery, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH (United States); Crawford, Paul [Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herfordshire AL9 7TA (United Kingdom); Esteve, Francois [INSERM U836-ESRF, 6 rue Horowitz, 38043 Grenoble (France); Brochard, Thierry; Renier, Michel; Requardt, Herwig; Le Duc, Geraldine [European Synchrotron Radiation Facility (ESRF), 6 rue Horowitz, 38043 Grenoble (France); Juurlink, Bernhard [Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK (Canada); Meguro, Kotoo [Departments of Surgery, University of Saskatchewan, Saskatoon, SK (Canada)

    2010-03-15

    Background: K-edge digital subtraction angiography (KEDSA) combined with the tunability of synchrotron beam yields an imaging technique that is highly sensitive to low concentrations of contrast agents. Thus, contrast agent can be administered intravenously, obviating the need for insertion of a guided catheter to deliver a bolus of contrast agent close to the target tissue. With the high-resolution detectors used at synchrotron facilities, images can be acquired at high spatial resolution. Thus, the KEDSA appears particularly suited for studies of neurovascular pathology in animal models, where the vascular diameters are significantly smaller than in human patients. Materials and methods: This feasibility study was designed to test the suitability of KEDSA after intravenous injection of iodine-based contrast agent for use in a pig model. Four adult male pigs were used for our experiments. Neurovascular angiographic images were acquired using KEDSA with a solid state Germanium (Ge) detector at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. Results: After intravenous injection of 0.9 ml/kg iodinated contrast agent (Xenetix), the peak iodine concentrations in the internal carotid and middle cerebral arteries reached 35 mg/ml. KEDSA images in radiography mode allowed the visualization of intracranial arteries of less than 1.5 mm diameter.

  7. Synchrotron-based intra-venous K-edge digital subtraction angiography in a pig model: A feasibility study

    International Nuclear Information System (INIS)

    Schueltke, Elisabeth; Fiedler, Stefan; Nemoz, Christian; Ogieglo, Lissa; Kelly, Michael E.; Crawford, Paul; Esteve, Francois; Brochard, Thierry; Renier, Michel; Requardt, Herwig; Le Duc, Geraldine; Juurlink, Bernhard; Meguro, Kotoo

    2010-01-01

    Background: K-edge digital subtraction angiography (KEDSA) combined with the tunability of synchrotron beam yields an imaging technique that is highly sensitive to low concentrations of contrast agents. Thus, contrast agent can be administered intravenously, obviating the need for insertion of a guided catheter to deliver a bolus of contrast agent close to the target tissue. With the high-resolution detectors used at synchrotron facilities, images can be acquired at high spatial resolution. Thus, the KEDSA appears particularly suited for studies of neurovascular pathology in animal models, where the vascular diameters are significantly smaller than in human patients. Materials and methods: This feasibility study was designed to test the suitability of KEDSA after intravenous injection of iodine-based contrast agent for use in a pig model. Four adult male pigs were used for our experiments. Neurovascular angiographic images were acquired using KEDSA with a solid state Germanium (Ge) detector at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. Results: After intravenous injection of 0.9 ml/kg iodinated contrast agent (Xenetix), the peak iodine concentrations in the internal carotid and middle cerebral arteries reached 35 mg/ml. KEDSA images in radiography mode allowed the visualization of intracranial arteries of less than 1.5 mm diameter.

  8. Synchrotron-based intra-venous K-edge digital subtraction angiography in a pig model: a feasibility study.

    Science.gov (United States)

    Schültke, Elisabeth; Fiedler, Stefan; Nemoz, Christian; Ogieglo, Lissa; Kelly, Michael E; Crawford, Paul; Esteve, Francois; Brochard, Thierry; Renier, Michel; Requardt, Herwig; Le Duc, Geraldine; Juurlink, Bernhard; Meguro, Kotoo

    2010-03-01

    K-edge digital subtraction angiography (KEDSA) combined with the tunability of synchrotron beam yields an imaging technique that is highly sensitive to low concentrations of contrast agents. Thus, contrast agent can be administered intravenously, obviating the need for insertion of a guided catheter to deliver a bolus of contrast agent close to the target tissue. With the high-resolution detectors used at synchrotron facilities, images can be acquired at high spatial resolution. Thus, the KEDSA appears particularly suited for studies of neurovascular pathology in animal models, where the vascular diameters are significantly smaller than in human patients. This feasibility study was designed to test the suitability of KEDSA after intravenous injection of iodine-based contrast agent for use in a pig model. Four adult male pigs were used for our experiments. Neurovascular angiographic images were acquired using KEDSA with a solid state Germanium (Ge) detector at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. After intravenous injection of 0.9 ml/kg iodinated contrast agent (Xenetix), the peak iodine concentrations in the internal carotid and middle cerebral arteries reached 35 mg/ml. KEDSA images in radiography mode allowed the visualization of intracranial arteries of less than 1.5mm diameter. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

  9. Vasovist-enhanced MR angiography

    International Nuclear Information System (INIS)

    Goyen, M.; Shamsi, K.; Schoenberg, S.O.

    2006-01-01

    Vasovist (MS-325) is the first intravascular contrast agent approved for use with magnetic resonance angiography in the European Union. Vasovist reversibly binds to albumin, providing extended intravascular enhancement compared to existing extracellular magnetic resonance contrast agents. Prior to approval, Vasovist underwent extensive testing to evaluate the safety and efficacy of the drug; the clinical trials program included blinded, placebo-controlled dose ranging, efficacy in a variety of vascular beds (AIOD, renal, pedal), examination of potential drug interaction with warfarin and comparison with XRA. The clinical trials show that Vasovist-enhanced MR angiography is safe and well-tolerated in patients with vascular disease, effective for the detection of vascular stenosis and aneurysms, significantly more accurate (both more sensitive and specific) than non-contrast MR angiography for the diagnosis of vascular stenoses, and similar to conventional angiography for the overall characterization of vascular disease, without the need for catheterization. (orig.)

  10. Vasovist-enhanced MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Goyen, M. [Univ. Medical Center, Hamburg-Eppendorf, Hamburg (Germany); Shamsi, K. [Berlex Lab., Inc., Montville, NJ (United States); Schoenberg, S.O. [Dept. of Clinical Radiology, Univ. Hospitals Grosshadern, Munich (Germany)

    2006-02-15

    Vasovist (MS-325) is the first intravascular contrast agent approved for use with magnetic resonance angiography in the European Union. Vasovist reversibly binds to albumin, providing extended intravascular enhancement compared to existing extracellular magnetic resonance contrast agents. Prior to approval, Vasovist underwent extensive testing to evaluate the safety and efficacy of the drug; the clinical trials program included blinded, placebo-controlled dose ranging, efficacy in a variety of vascular beds (AIOD, renal, pedal), examination of potential drug interaction with warfarin and comparison with XRA. The clinical trials show that Vasovist-enhanced MR angiography is safe and well-tolerated in patients with vascular disease, effective for the detection of vascular stenosis and aneurysms, significantly more accurate (both more sensitive and specific) than non-contrast MR angiography for the diagnosis of vascular stenoses, and similar to conventional angiography for the overall characterization of vascular disease, without the need for catheterization. (orig.)

  11. MO-FG-CAMPUS-IeP1-01: Alternative K-Edge Filters for Low-Energy Image Acquisition in Contrast Enhanced Spectral Mammography

    Energy Technology Data Exchange (ETDEWEB)

    Shrestha, S; Vedantham, S; Karellas, A [University of Massachusetts Medical School, Worcester, MA (United States)

    2016-06-15

    Purpose: In Contrast Enhanced Spectral Mammography (CESM), Rh filter is often used during low-energy image acquisition. The potential for using Ag, In and Sn filters, which exhibit K-edge closer to, and just below that of Iodine, instead of the Rh filter, was investigated for the low-energy image acquisition. Methods: Analytical computations of the half-value thickness (HVT) and the photon fluence per mAs (photons/mm2/mAs) for 50µm Rh were compared with other potential K-edge filters (Ag, In and Sn), all with K-absorption edge below that of Iodine. Two strategies were investigated: fixed kVp and filter thickness (50µm for all filters) resulting in HVT variation, and fixed kVp and HVT resulting in variation in Ag, In and Sn thickness. Monte Carlo simulations (GEANT4) were conducted to determine if the scatter-to-primary ratio (SPR) and the point spread function of scatter (scatter PSF) differed between Rh and other K-edge filters. Results: Ag, In and Sn filters (50µm thick) increased photon fluence/mAs by 1.3–1.4, 1.8–2, and 1.7–2 at 28-32 kVp compared to 50µm Rh, which could decrease exposure time. Additionally, the fraction of spectra closer to and just below Iodine’s K-edge increased with these filters, which could improve post-subtraction image contrast. For HVT matched to 50µm Rh filtered spectra, the thickness range for Ag, In, and Sn were (41,44)µm, (49,55)µm and (45,53)µm, and increased photon fluence/mAs by 1.5–1.7, 1.6–2, and 1.6–2.2, respectively. Monte Carlo simulations showed that neither the SPR nor the scatter PSF of Ag, In and Sn differed from Rh, indicating no additional detriment due to x-ray scatter. Conclusion: The use of Ag, In and Sn filters for low-energy image acquisition in CESM is potentially feasible and could decrease exposure time and may improve post-subtraction image contrast. Effect of these filters on radiation dose, contrast, noise and associated metrics are being investigated. Funding Support: Supported in

  12. Contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Bosmans, H.; Marchal, G.

    1996-01-01

    Despite many optimizations, the current limitations of plain MR angiography include: Saturation that impairs the visualization of veins and arteries with slow flow and spin-dephasing signal voids in locations with turbulent flow. Recently, the use of contrast agents has been proposed to cope with these remaining problems. Because of induced shortening of the T1 of the blood, saturation in the blood vessels is overcome. As a result, arteries and veins are visualized with the same signal intensity, which makes the technique less flow-dependent. In combination with short T1-weighted acquisitions, today CE MRA can be obtained while the patient is holding his breath. This last approach is most promising for abdominal applications since the respiratory motion can be frozen. As these acquisitions also use very short echo times, spin dephasing can be reduced. In conclusion, the use of contrast agents has greatly increased the clinical usefulness of MR angiography. (orig.) [de

  13. K-edge densitometer (KED)

    Energy Technology Data Exchange (ETDEWEB)

    Sprinkle, J.K.; Hansen, W.J.

    1993-02-11

    In 1979, a K-edge densitometer (KED) was installed by the Safeguards Assay group from Los Alamos National Laboratory in the PNC reprocessing plant at Tokai-mura, Japan. It uses an active nondestructive assay technique, KED, to measure the plutonium concentration of the product solution. The measurement uncertainty of an assay depends on the count time chosen, but can be 0.5% or better. The computer hardware and software were upgraded in 1992. This manual describes the operation of the instrument, with an emphasis on the user interface to the software.

  14. Closing in on the K Edge : Coronary CT Angiography at 100, 80, and 70 kV-Initial Comparison of a Second-versus a Third-Generation Dual-Source CT System

    NARCIS (Netherlands)

    Meyer, Mathias; Haubenreisser, Holger; Schoepf, U. Joseph; Vliegenthart, Rozemarijn; Leidecker, Christianne; Allmendinger, Thomas; Lehmann, Ralf; Sudarski, Sonja; Borggrefe, Martin; Schoenberg, Stefan O.; Henzler, Thomas

    2014-01-01

    Purpose: To prospectively evaluate radiation and contrast medium requirements for performing high-pitch coronary computed tomographic (CT) angiography at 70 kV using a third-generation dual-source CT system in comparison to a second-generation dual-source CT system. Materials and Methods: All

  15. The efficacy of K-edge filters in diagnostic radiology

    International Nuclear Information System (INIS)

    Williamson, B.D.P.; van Doorn, T.

    1994-01-01

    The application of K-edge filters in diagnostic has been investigated by many workers for over twenty years. These investigations have analysed the effects of such filters on image quality and radiation dose as well as the practicalities of their application. This paper presents a synopsis of the published works and concludes that K-edge filters do not perceptibly improve image quality and make only limited reductions in patient dose. K-edge filters are also costly to purchase and potentially result in a reduction in the cost effectiveness of x-ray examinations by increasing the x-ray tube loading. Equivalent contrast enhancement and dose reductions can be achieved by the assiduous choice of non-selective filters. 51 refs., 2 tab., 6 figs

  16. Contrast-enhanced MR angiography in Leriche's syndrome

    International Nuclear Information System (INIS)

    Link, J.; Steffens, J.C.; Brossmann, J.; Heller, M.; Loose, R.

    1998-01-01

    Purpose: To determine the usefulness of contrast-enhanced MR angiography for the diagnosis of Leriche's syndrome. Material and methods: Leriche's syndrome was seen in 7 patients via DSA. In [dition, contrast-enhanced MR angiography was performed (T R 7.8 ms/T E 2.1 ms, flip angle 30 , slab thickness 116 mm, slice thickness 1.82 mm, 64 partitions, FOV 500x438 mm, matrix 224x512). Results: Diagnosis of Leriche's syndrome was possible by contrast-enhanced MR angiography in each case. Visualisation of the femoral arteries was not possible in two patients by intraarterial DSA, in three other patients there was an insufficient contrast in the femoral arteries with DSA. Contrast-enhanced MR angiography revealed good visualisation of the femoral arteries in these patients. In [dition, contrast-enhanced MR angiography allowed complete visualisation of the patent lower limb arteries. In intraarterial DSA visualisation of the lower limb arteries was achieved reached in only one patient, but was incomplete. Conclusion: Contrast-enhanced MR angiography yielded the correct diagnosis of Leriche's syndrome in all 7 patients. Contrast-enhanced MR angiography was superior to DSA in the assessment of the distal run-off vessels in five of seven patients. (orig.) [de

  17. Ion charge-state production and photoionization near the K edge in argon and potassium

    International Nuclear Information System (INIS)

    Berry, H.G.; Azuma, Y.; Cowan, P.L.; Gemmell, D.S.; LeBrun, T.; Amusia, M.Y.

    1994-01-01

    We have measured the time-of-flight charge distributions of ions of argon and potassium following x-ray absorption at energies near their respective K edges. We confirm previously observed enhancements of the higher charge states at energies up to 100 eV below the K edge in argon. The measurements confirm recent calculations suggesting excitation of a virtual 1s state in this energy range

  18. Field demonstration of a portable, X-ray, K-edge heavy-metal detector

    International Nuclear Information System (INIS)

    Jensen, T.; Aljundi, T.; Whitmore, C.; Zhong, H.; Gray, J.N.

    1997-01-01

    Under the Characterization, Monitoring, and Sensor Technology Crosscutting Program, the authors have designed and built a K-edge heavy metal detector that measures the level of heavy metal contamination inside closed containers in a nondestructive, non-invasive way. The device employs a volumetric technique that takes advantage of the X-ray absorption characteristics of heavy elements, and is most suitable for characterization of contamination inside pipes, processing equipment, closed containers, and soil samples. The K-edge detector is a fast, efficient, and cost-effective in situ characterization tool. More importantly, this device will enhance personnel safety while characterizing radioactive and toxic waste. The prototype K-edge system was operated at the Materials and Chemistry Laboratory User Facility at the Oak Ridge K-25 Site during February 1997. Uranium contaminated pipes and valves from a UF 6 feed facility were inspected using the K-edge technique as well as a baseline nondestructive assay method. Operation of the K-edge detector was demonstrated for uranium contamination ranging from 10 to 6,000 mg/cm 2 and results from the K-edge measurements were found to agree very well with nondestructive assay measurements

  19. Angiography

    International Nuclear Information System (INIS)

    Grinnell, V.S.; Mehringer, C.M.; Hieshima, G.B.

    1987-01-01

    The history of angiography is short, with its centennial approaching. A very brief review of milestones begins with the discovery of x-rays in 1895. Only a few months later contrast agents too toxic for human use were being injected into cadavers, severed limbs, and animals. The next major developments came in the late 1970s when percutaneous translumbar aortography and cerebral angiography were described. Contrast agents were now less toxic, and clinically useful angiography was a reality. In 1953 a technique for percutaneous vascular catheterization which formed the basis of many catheterization techniques to follow was described. In the 1970s the development of less invasive diagnostic methods such as computed tomography and diagnostic ultrasound decreased the indications for angiography, but newer interventional techniques such as embolization therapy and angioplasty have taken up the slack. Angiography remains the most important way to demonstrate vascular diseases graphically. Specific techniques such as angioplasty and digital subtraction angiography will be dealt with in other chapters. The authors hope to provide an overview of major areas of angiographic utilization. The basic techniques of arterial puncture and catheterization have been well described elsewhere

  20. Gadolinium-enhanced MR angiography of arterial occlusive disease in lower extremity : comparison with conventional digital subtraction angiography

    International Nuclear Information System (INIS)

    Shin, Sang June; Koh, Young Hwan; Cha, Joo Hee; Kim, Hyu Beom; Chung, Jin Wook; Park, Jae Hyung

    2000-01-01

    To compare the diagnostic value of gadolinium-enhanced MR angiography with that of conventional digital subtraction angiography for the evaluation of lower extremity arterial occlusive diseases. In 26 patients with symptomatic lower extremity arterial occlusive disease, both conventional digital subtraction angiography (DSA) and gadolinium-enhanced MR angiography (CE-MRA) were performed during the same week. MR angiography was performed using three-dimensional gradient-echo acquisition before, and two sequential acquisitions after, the administration of gadolinium (0.2 mmol/kg). In 23 patients, two separate, contiguous areas were scanned using additional doses. In three patients, only one field with a suspicious lesion was scanned. Three radiologists independently analyzed the CE-MRA and DSA findings of each vascular segment (20 segments per arterial tree) for the presence of obstructive lesions; the grade assigned was either mild or none (less than 50%), stenotic (50%-99%), or occlusion (100%). From among a total of 462 segments, DSA detected 99 which were significantly narrowed (stenosis, 33; occlusion, 66). Using MR angiography, 102 segments (stenosis 39; occlusion, 63) were identified, and 94 lesions (stenosis, 32; occlusion, 62) were graded correctly. Seven lesions were overestimated and four were underestimated. For the detection of hemodynamically significant stenosis or occlusions using MR angiography, sensitivity, specificity, and diagnostic accuracy were 95%, 98%, and 98% (G=3D0.995, P less than 0.001), respectively. To prove the absence of lesions, we repeated DSA in two patients with arterial spasm due to puncture. Three occluded segments seen on DSA, which revealed intact segments on MR angiography, suggested slow distal flow after reconstitution. For the evaluation of lower extremity arterial occlusive disease, the diagnostic value of gadolinium-enhanced MR angiography is comparable with that of digital subtraction angiography. The advantages of the

  1. Gadolinium-enhanced MR angiography of the thoracoabdominal aorta diseases

    International Nuclear Information System (INIS)

    D'Ippolito, Giuseppe; Wolosker, Nelson; Galvao Filho, Mario; Kalil, Jorge A.; Wolosker, Angela; Borri, Maria Lucia

    1998-01-01

    Gadolinium-enhanced MR angiography (GEMRA) of the thoracoabdominal aorta is a noninvasive technique that can rapidly delineate the branch vessels diseases, without flow or respiration artifacts, obtained with non contrast MRA. The objective of this paper is to show the main clinical applications of GEMRA, compared to non contrast sequences. We have evaluated 30 patients with thorocoabdominal aorta diseases. These patients have been examined with GEMRA (3D, FFE sequences) obtained after 30 mlIV contrast injection and non contrast MRA (2D-TOF sequences). In our experience, gadolinium-enhanced MRA is a high resolution and speedy technique with advantages over non contrast MRA. (author)

  2. Evaluation of the pedal artery: comparison of three-dimensional gadolinium-enhanced MR angiography with digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Min; Kang, Sung Gwon; Byun, Joo Nam; Kim, Young Cheol; Choi, Jeong Yeol; Kim, Dong Hyun [College of Medicine, Chosun Univ., Kwangju (Korea, Republic of)

    2002-07-01

    To compare the three-dimensional gadolinium-enhanced MR angiography with digital subtraction angiography (DSA) for evaluation of the pedal artery. In 12 extremities of 11 patients, both digital subtraction angiography (DSA) and contrast-enhanced MR angiography (CE-MR angiography) were performed during the same week. Among ten of the 11 patients, the following conditions were present: atherosclerosis (n=4), diabetic foot (n=3), Buerger's disease (n=1), calciphylactic arteriopathy (n=1) and arteriovenous malformation of the foot (n=1). The remaining patient underwent angiography prior to flap surgery. For MR angiography, a 1.5T system using an extremity or head coil was used. A three-dimensional FISP (fast imaging with steady state precession) sequence was obtained before enhancement, followed by four sequential acquisitions (scan time, 20 secs, scan interval time, 10 secs) 10 seconds after intravenous bolus injection of normal saline (total 10 cc), following intravenous administration of gadolinium (0.02 mmol/kg, 3 ml/sec). Arterial segments of the ankle and foot were classified as the anterior or posterior tibial artery, the distal peroneal artery, the medial or lateral plantar artery, the pedal arch, and the dorsalis pedis artery. Two radiologists independently analysed visualization of each arteraial segment and the mean of visible arterial segments in one extreminty using CE-MR angiography and DSA. Among 84 arterial segments, 16 were invisible at both CE-MR angiography and DSA, while 39 were demonstrated by both modalities. Twenty-six segments were visible only at CE-MR angiography and three only at DSA. CE-MR angiography displayed a higher number of arterial segments than DSA (mean, 5.42 vs. mean 3.50, respectively), a difference which was statistically significant (p<0.000). The difference between each arterial segment was not statistically significant, except for the dorsalis pedis artery (t test, p<0.000). In that it provides additional information for

  3. Si K-edge XANES study of SiOxCyHz amorphous polymeric materials

    International Nuclear Information System (INIS)

    Chaboy, J.; Barranco, A.; Yanguas-Gil, A.; Yubero, F.; Gonzalez-Elipe, A. R.

    2007-01-01

    This work reports on x-ray absorption spectroscopy study at the Si K edge of several amorphous SiO x C y H z polymers prepared by plasma-enhanced chemical-vapor deposition with different C/O ratios. SiO 2 and SiC have been used as reference materials. The comparison of the experimental Si K-edge x-ray absorption near-edge structure spectra with theoretical computations based on multiple scattering theory has allowed us to monitor the modification of the local coordination around Si as a function of the overall C/O ratio in this kind of materials

  4. K-edge Radiography and applications to Cultural Heritage

    OpenAIRE

    Albertin, Fauzia

    2011-01-01

    The present work of thesis is focused on application of X-ray K-edge technique to paintings. This technique allows one to achieve a topographic map of a pigment on the whole surface of the painting. The digital acquisition of radiographic images by using monochromatic X-ray beams allows to take advantage of the sharp rise of X-ray absorption coefficient of the elements, the K-edge discontinuity. Working at different energies, bracketing the K-edge peak, allows recognition ...

  5. Parameters Influencing Sulfur Speciation in Environmental Samples Using Sulfur K-Edge X-Ray Absorption Near-Edge Structure

    Directory of Open Access Journals (Sweden)

    Siwatt Pongpiachan

    2012-01-01

    Full Text Available This paper aims to enhance the credibility of applying the sulfur K-edge XANES spectroscopy as an innovative “fingerprint” for characterizing environmental samples. The sensitivities of sulfur K-edge XANES spectra of ten sulfur compound standards detected by two different detectors, namely, Lytle detector (LyD and Germanium detector (GeD, were studied and compared. Further investigation on “self-absorption” effect revealed that the maximum sensitivities of sulfur K-edge XANES spectra were achieved when diluting sulfur compound standards with boron nitride (BN at the mixing ratio of 0.1%. The “particle-size” effect on sulfur K-edge XANES spectrum sensitivities was examined by comparing signal-to-noise ratios of total suspended particles (TSP and particulate matter of less than 10 millionths of a meter (PM10 collected at three major cities of Thailand. The analytical results have demonstrated that the signal-to-noise ratios of sulfur K-edge XANES spectra were positively correlated with sulfate content in aerosols and negatively connected with particle sizes. The combination of hierarchical cluster analysis (HCA and principal component analysis (PCA has proved that sulfur K-edge XANES spectrum can be used to characterize German terrestrial soils and Andaman coastal sediments. In addition, this study highlighted the capability of sulfur K-edge XANES spectra as an innovative “fingerprint” to distinguish tsunami backwash deposits (TBD from typical marine sediments (TMS.

  6. Silicon K-edge XANES spectra of silicate minerals

    Science.gov (United States)

    Li, Dien; Bancroft, G. M.; Fleet, M. E.; Feng, X. H.

    1995-03-01

    Silicon K-edge x-ray absorption near-edge structure (XANES) spectra of a selection of silicate and aluminosilicate minerals have been measured using synchrotron radiation (SR). The spectra are qualitatively interpreted based on MO calculation of the tetrahedral SiO{4/4-}cluster. The Si K-edge generally shifts to higher energy with increased polymerization of silicates by about 1.3 eV, but with considerable overlap for silicates of different polymerization types. The substitution of Al for Si shifts the Si K-edge to lower energy. The chemical shift of Si K-edge is also sensitive to cations in more distant atom shells; for example, the Si K-edge shifts to lower energy with the substitution of Al for Mg in octahedral sites. The shifts of the Si K-edge show weak correlation with average Si-O bond distance (dSi-O), Si-O bond valence (sSi-O) and distortion of SiO4 tetrahedra, due to the crystal structure complexity of silicate minerals and multiple factors effecting the x-ray absorption processes.

  7. Recent advances in contrast-enhanced magnetic resonance angiography

    International Nuclear Information System (INIS)

    Meaney, J.F.M.; Goyen, M.

    2007-01-01

    Magnetic resonance angiography (MRA) provides a means of visualizing vascular structures noninvasively and is increasingly replacing conventional X-ray angiography in routine use. Contrast-enhanced MRA (CE-MRA), in which gadolinium contrast agents are used to shorten the T1 relaxation, offers increased resolution and higher signal-to-noise ratio compared with earlier flow-dependent [time-of-flight (TOF) or phase-contrast (PC)] techniques. Currently available contrast agents differ in their ability to lower T1 values, and hence the choice of contrast agent is an important consideration in the successful use of CE-MRA. Gadofosveset trisodium (Vasovist, Bayer Schering Pharma AG, Berlin, Germany) is the first of a new class of intravascular contrast agents. This agent is extensively (approximately 85%) and reversibly bound to human serum albumin and is retained within the vasculature thus allowing steady-state imaging to be perform-ed. An additional benefit is that gado0fosveset offers higher relaxivity compared with other contrast agents, thus giving a lower blood T1 values which also makes it ideal for first-pass imaging. Clinical trials have consistently shown that gadofosveset enhanced MRA is more sensitive, specific and accurate than time-of-flight MRA, gives fewer uninterpretable scans and affords greater diagnostic confidence. Intravascular contrast agents such as gadofosveset, therefore, offer the potential for improved vascular imaging. (orig.)

  8. Comparison of iodine K-edge subtraction and fluorescence subtraction imaging in an animal system

    International Nuclear Information System (INIS)

    Zhang, H.; Zhu, Y.; Bewer, B.; Zhang, L.; Korbas, M.; Pickering, I.J.; George, G.N.; Gupta, M.; Chapman, D.

    2008-01-01

    K-Edge Subtraction (KES) utilizes the discontinuity in the X-ray absorption across the absorption edge of the selected contrast element and creates an image of the projected density of the contrast element from two images acquired just above and below the K-edge of the contrast element. KES has proved to be powerful in coronary angiography, micro-angiography, bronchography, and lymphatic imaging. X-ray fluorescence imaging is a successful technique for the detection of dilute quantities of elements in specimens. However, its application at high X-ray energies (e.g. at the iodine K-edge) is complicated by significant Compton background, which may enter the energy window set for the contrast material's fluorescent X-rays. Inspired by KES, Fluorescence Subtraction Imaging (FSI) is a technique for high-energy (>20 keV) fluorescence imaging using two different incident beam energies just above and below the absorption edge of a contrast element (e.g. iodine). The below-edge image can be assumed as a 'background' image, which includes Compton scatter and fluorescence from other elements. The above-edge image will contain nearly identical spectral content as the below-edge image but will contain the additional fluorescence of the contrast element. This imaging method is especially promising with thick objects with dilute contrast materials, significant Compton background, and/or competing fluorescence lines from other materials. A quality factor is developed to facilitate the comparison. The theoretical value of the quality factor sets the upper limit that an imaging method can achieve when the noise is Poisson limited. The measured value of this factor makes two or more imaging methods comparable. Using the Hard X-ray Micro-Analysis (HXMA) beamline at the Canadian Light Source (CLS), the techniques of FSI and KES were critically compared, with reference to radiation dose, image acquisition time, resolution, signal-to-noise ratios, and quality factor

  9. Contrast-enhanced MR angiography of abdominal vessels: Is there still a role for angiography?

    Energy Technology Data Exchange (ETDEWEB)

    Vosshenrich, R.; Fischer, U. [Department of Radiology, Georg-August-Universitaet Goettingen (Germany)

    2002-01-01

    The purpose of this review article is to describe recent advantages in contrast-enhanced (CE) three-dimensional (3D) magnetic resonance angiography (MRA) in comparison with other vascular imaging techniques, and to discuss their current clinical applications for the imaging of abdominal vessels. Principles and technical considerations are presented and clinical applications are reviewed for different vascular diseases. In ruptured aortic aneurysms and acute dissections CT is the method of first choice. Contrast-enhanced 3D MRA can be well used for therapeutic planning and follow-up in patients with stable disease. A comprehensive MR examination including CE 3D MRA, MR urography and MR nephrogram has the potential to replace the conventional studies for the evaluation of renal vascular disease. It is an accurate method for imaging the origins of coeliac and superior mesenteric arteries, although the image resolution is too low for reliable assessment of the inferior mesenteric artery. Contrast-enhanced 3D MRA has emerged as the method of choice for studying the portal venous system in liver transplant recipients, in patients with portal hypertension and in cases with abdominal tumours for preoperative evaluation. Additional non-invasive flow measurements are useful in monitoring portal hypertension. The abdominal veins can be well imaged using unenhanced MR techniques. Imaging may be facilitated with intravascular contrast media. Contrast-enhanced 3D MRA can replace intra-arterial DSA for diagnosis, therapy planning and follow-up in patients with abdominal vascular disease. Catheter-based arteriography will still be used for interventional procedures such as percutaneous transluminal angioplasty, stent placement and embolisation. (orig.)

  10. Material Discrimination Based on K-edge Characteristics

    Directory of Open Access Journals (Sweden)

    Peng He

    2013-01-01

    Full Text Available Spectral/multienergy CT employing the state-of-the-art energy-discriminative photon-counting detector can identify absorption features in the multiple ranges of photon energies and has the potential to distinguish different materials based on K-edge characteristics. K-edge characteristics involve the sudden attenuation increase in the attenuation profile of a relatively high atomic number material. Hence, spectral CT can utilize material K-edge characteristics (sudden attenuation increase to capture images in available energy bins (levels/windows to distinguish different material components. In this paper, we propose an imaging model based on K-edge characteristics for maximum material discrimination with spectral CT. The wider the energy bin width is, the lower the noise level is, but the poorer the reconstructed image contrast is. Here, we introduce the contrast-to-noise ratio (CNR criterion to optimize the energy bin width after the K-edge jump for the maximum CNR. In the simulation, we analyze the reconstructed image quality in different energy bins and demonstrate that our proposed optimization approach can maximize CNR between target region and background region in reconstructed image.

  11. Comparison of digital subtraction angiography with gadolinium-enhanced magnetic resonance angiography in the diagnosis of renal artery stenosis

    International Nuclear Information System (INIS)

    Thornton, J.; O'Callaghan, J.; Varghese, J.C.; Lee, M.J.; Walshe, J.; O'Brien, E.

    1999-01-01

    Renal artery stenosis (RAS) is a treatable cause of hypertension and renal failure for which no ideal screening technique is currently available. We evaluated the use of dynamic gadolinium-enhanced magnetic resonance angiography (MRA) for the diagnosis of RAS. Sixty-two patients with secondary hypertension were enrolled in the study. All patients had conventional renal angiography and gadolinium enhanced MRA. The sequence used was a 3D FMP SPGR sequence with the following parameters (TR: 26 ms, TE: 6.9 ms, flip angle 40 , field of view 36 x 36 cm, matrix 246 x 256, 1 excitation). Gadolinium 0.3 mmol/kg was administered and 60 1.5-mm-thick partitions were obtained over a duration of 3.5 min. The MRA images were then compared with conventional digital subtraction angiography (DSA) images. Conventional DSA demonstrated 138 renal arteries, whereas gadolinium-enhanced MRA demonstrated 129 (93 %). Twenty-one renal artery stenoses and four occluded arteries were seen at conventional DSA. Gadolinium-enhanced MRA had a sensitivity of 88 %, specificity of 98 %, accuracy of 96 %, positive predictive value of 92 % and negative predictive value of 97 % when compared with conventional DSA. Gadolinium-enhanced MRA is an accurate technique for identifying patients with RAS. It is less sensitive in picking up accessory renal arteries. (orig.)

  12. K-edge subtraction synchrotron X-ray imaging in bio-medical research.

    Science.gov (United States)

    Thomlinson, W; Elleaume, H; Porra, L; Suortti, P

    2018-05-01

    High contrast in X-ray medical imaging, while maintaining acceptable radiation dose levels to the patient, has long been a goal. One of the most promising methods is that of K-edge subtraction imaging. This technique, first advanced as long ago as 1953 by B. Jacobson, uses the large difference in the absorption coefficient of elements at energies above and below the K-edge. Two images, one taken above the edge and one below the edge, are subtracted leaving, ideally, only the image of the distribution of the target element. This paper reviews the development of the KES techniques and technology as applied to bio-medical imaging from the early low-power tube sources of X-rays to the latest high-power synchrotron sources. Applications to coronary angiography, functional lung imaging and bone growth are highlighted. A vision of possible imaging with new compact sources is presented. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  13. Carbon K-edge spectra of carbonate minerals.

    Science.gov (United States)

    Brandes, Jay A; Wirick, Sue; Jacobsen, Chris

    2010-09-01

    Carbon K-edge X-ray spectroscopy has been applied to the study of a wide range of organic samples, from polymers and coals to interstellar dust particles. Identification of carbonaceous materials within these samples is accomplished by the pattern of resonances in the 280-320 eV energy region. Carbonate minerals are often encountered in the study of natural samples, and have been identified by a distinctive resonance at 290.3 eV. Here C K-edge and Ca L-edge spectra from a range of carbonate minerals are presented. Although all carbonates exhibit a sharp 290 eV resonance, both the precise position of this resonance and the positions of other resonances vary among minerals. The relative strengths of the different carbonate resonances also vary with crystal orientation to the linearly polarized X-ray beam. Intriguingly, several carbonate minerals also exhibit a strong 288.6 eV resonance, consistent with the position of a carbonyl resonance rather than carbonate. Calcite and aragonite, although indistinguishable spectrally at the C K-edge, exhibited significantly different spectra at the Ca L-edge. The distinctive spectral fingerprints of carbonates provide an identification tool, allowing for the examination of such processes as carbon sequestration in minerals, Mn substitution in marine calcium carbonates (dolomitization) and serpentinization of basalts.

  14. Carbon K-edge Spectra of Carbonate Minerals

    Energy Technology Data Exchange (ETDEWEB)

    Brandes, J.; Wirick, S; Jacobsen, C

    2010-01-01

    Carbon K-edge X-ray spectroscopy has been applied to the study of a wide range of organic samples, from polymers and coals to interstellar dust particles. Identification of carbonaceous materials within these samples is accomplished by the pattern of resonances in the 280-320 eV energy region. Carbonate minerals are often encountered in the study of natural samples, and have been identified by a distinctive resonance at 290.3 eV. Here C K-edge and Ca L-edge spectra from a range of carbonate minerals are presented. Although all carbonates exhibit a sharp 290 eV resonance, both the precise position of this resonance and the positions of other resonances vary among minerals. The relative strengths of the different carbonate resonances also vary with crystal orientation to the linearly polarized X-ray beam. Intriguingly, several carbonate minerals also exhibit a strong 288.6 eV resonance, consistent with the position of a carbonyl resonance rather than carbonate. Calcite and aragonite, although indistinguishable spectrally at the C K-edge, exhibited significantly different spectra at the Ca L-edge. The distinctive spectral fingerprints of carbonates provide an identification tool, allowing for the examination of such processes as carbon sequestration in minerals, Mn substitution in marine calcium carbonates (dolomitization) and serpentinization of basalts.

  15. Contrast-enhanced magnetic resonance angiography of persistent fifth aortic arch in children

    International Nuclear Information System (INIS)

    Zhong, Yumin; Zhu, Ming; Sun, Aimin; Li, Yuhua; Jaffe, Richard B.; Gao, Wei

    2007-01-01

    Cine angiography and echocardiography have been utilized to diagnose congenital aortic arch anomalies. However, the visualization of great vessels by echocardiography is limited, while cine angiography requires cardiac catheterization with ionizing radiation. Contrast-enhanced magnetic resonance angiography (MRA) is a noninvasive modality suitable for visualization of congenital aortic arch anomalies. To evaluate the utility of contrast-enhanced MRA in the diagnosis of persistent fifth aortic arch, a rare congenital aortic arch anomaly, and to compare the diagnostic accuracy of MRA with that of echocardiography and cine angiography. In four pediatric patients, contrast-enhanced MRA studies were performed for diagnosing persistent fifth aortic arch. The findings of MRA were compared with echocardiographic findings and confirmed by cine angiography and operation. Transthoracic surface echocardiography noted an aberrant vessel arising from the ascending aorta in two of four patients; the etiology of this vessel was uncertain. In the other two patients a diagnosis of coarctation was made. Of the four patients, only one was diagnosed with interruption of the aortic arch. Contrast-enhanced MRA clarified uncertain echocardiographic findings, enabling the correct diagnosis of persistent fifth aortic arch with fourth aortic arch interruption in all four patients. Contrast-enhanced MRA is a safe, accurate, and fast imaging technique for the evaluation of persistent fifth aortic arch and may obviate the need for conventional cine angiography. Cardiac catheterization may be reserved for some types of complicated congenital heart disease and for obtaining hemodynamic information. (orig.)

  16. Comparison of gadofosveset-enhanced three-dimensional magnetic resonance angiography with digital subtraction angiography for lower-extremity peripheral arterial occlusive disease

    International Nuclear Information System (INIS)

    Grijalba, Fermin Urtasun; Esandi, Mercedes Ciriza

    2010-01-01

    Background: Minimally invasive imaging techniques are increasingly used for clinical decision making in patients with peripheral arterial occlusive disease (PAOD). Purpose: To assess whether gadofosveset-enhanced three-dimensional (3D) magnetic resonance (MR) angiography could replace digital subtraction angiography (DSA) for the evaluation of lower-extremity PAOD. Material and Methods: Thirty patients with symptomatic PAOD underwent prospectively both MR angiography and DSA. Gadofosveset-enhanced 3D MR angiography was performed on a 1.5T system equipped with a peripheral angio matrix coil. Four blinded observers independently analyzed MR angiograms and DSA images. The lower arterial vascular system was divided into three anatomic segments (aortoiliac, femoropopliteal, infrapopliteal) for review. The status of each segment was graded as normal, stenosis less than 50%, stenosis greater than 50%, or occluded and/or aneurismatic. Principal and secondary lesions were reported. Results: Although interobserver agreement for both was excellent, it was higher for DSA (?=0.92) than for MR angiography (?=0.86) for reporting the principal and secondary lesions in all segments. For different anatomic locations, the interobserver agreement of MR angiography and DSA was as follows: aortoiliac (?=0.93, k=0.95), femoropopliteal (?=0.86, k=0.90), and infrapopliteal (?=0.78, k=0.85). The lowest agreement was found for MR angiography on infrapopliteal segments (?=0.78). In four (13.3%) cases, MR angiography showed lesions that were not found by DSA. Five (16.6%) aneurysm cases, not observed by DSA, were shown by MR angiography. Conclusion: Gadofosveset-enhanced 3D MR angiography can be proposed for first-line imaging in the management of lower-limb PAOD patients and permits the selective use of DSA as a second-line examination when MR angiography fails or in an endovascular approach

  17. A simulation study of enhancement duration in three-dimensional contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Ohkubo, Masaki; Ohgoshi, Yukio; Inoue, Tomoko; Naito, Kenichi; Suzuki, Kiyotaka

    2001-01-01

    In our study on three-dimensional (3D) contrast-enhanced MR angiography we performed a computer simulation to investigate quantitative vessel visibility. In the simulation, we evaluated the relative loss of signal intensity in a vessel due to shortened duration of contrast-enhancement. The mid-point of enhancement-duration was assumed to be at the point in which the data in the center of k-space (k y axis) was acquired. Signal intensity of a vessel decreased as the enhancement-duration was shortened and the diameter of the vessel was decreased. When the duration was shortened 40%, the signal intensity of a vessel in which the diameter was more than 2 pixels was preserved by approximately 70% or more. This suggests that the vessel visibility is high. When the duration was shortened 20%, the signal intensity of a vessel in which the diameter was less than 2 pixels decreased to less than approximately 40% or less. The simulation was confirmed by using 3D MR angiography with a tube phantom filled with Gd-DTPA to simulate a vessel model. At anytime during data acquisition, we could set the phantom on the region being scanned or take it out by using the ''pause'' function of the MR scanner. This made it possible to change the enhancement-duration to match the simulation. Results of the phantom study were comparable to those of the simulation, suggesting that the simulation was valid. Our results and simple techniques for both the simulation and the phantom study using the ''pause'' function, were considered useful in the study of 3D MR angiography. (author)

  18. Contrast-enhanced MR angiography vs intra-arterial digital subtraction angiography for carotid imaging: activity-based cost analysis

    International Nuclear Information System (INIS)

    U-King-Im, Jean Marie; Cross, Justin J.; Higgins, Nicholas J.; Graves, Martin J.; Antoun, Nagui M.; Gillard, Jonathan H.; Hollingworth, William; Trivedi, Rikin A.; Kirkpatrick, Peter J.

    2004-01-01

    The aim of this study was to compare the costs of performing contrast-enhanced MR angiography (CE MRA) with intra-arterial digital subtraction angiography (DSA) for the evaluation of carotid atherosclerotic disease. Activity-based cost analysis was used to identify the costs of performing each procedure. The variable direct costs of performing CE MRA and DSA were determined in 20 patients by using detailed time and motion studies. All personnel directly involved in the cases were tracked to the nearest minute and all consumable items used were recorded. Moreover, procedure times were prospectively recorded for an additional 80 patients who underwent both DSA and CE MRA. The variable direct costs of bed usage in the angiography day-case unit, all direct fixed costs as well as indirect costs were assessed from hospital and departmental accounting records. Total costs for each procedure were calculated and compared using Wilcoxon signed-rank sum test. Mean aggregate costs were and euro;721 for DSA and and euro;306 for CE MRA, resulting in potential savings of and euro;415 per patient (p<0.0001). On average, a DSA procedure thus cost approximately 2.4 (95% confidence intervals: 2.2-2.6) times more than CE MRA to our medical institution. Sensitivity analyses confirmed the robustness of our conclusions across wide ranges of plausible values for various parameters. Assuming equal diagnostic performance, institutions may have substantial cost savings if CE MRA is used instead of DSA for carotid imaging. (orig.)

  19. Contrast-enhanced MR angiography vs intra-arterial digital subtraction angiography for carotid imaging: activity-based cost analysis

    Energy Technology Data Exchange (ETDEWEB)

    U-King-Im, Jean Marie; Cross, Justin J.; Higgins, Nicholas J.; Graves, Martin J.; Antoun, Nagui M.; Gillard, Jonathan H. [University Department of Radiology, Addenbrooke' s Hospital, CB2 2QQ, Cambridge (United Kingdom); Hollingworth, William [Department of Radiology, University of Washington, WA 98103, Seattle (United States); Trivedi, Rikin A. [University Department of Radiology, Addenbrooke' s Hospital, CB2 2QQ, Cambridge (United Kingdom); Academic Department of Neurosurgery, Addenbrooke' s Hospital, CB2 2QQ, Cambridge (United Kingdom); Kirkpatrick, Peter J. [Academic Department of Neurosurgery, Addenbrooke' s Hospital, CB2 2QQ, Cambridge (United Kingdom)

    2004-04-01

    The aim of this study was to compare the costs of performing contrast-enhanced MR angiography (CE MRA) with intra-arterial digital subtraction angiography (DSA) for the evaluation of carotid atherosclerotic disease. Activity-based cost analysis was used to identify the costs of performing each procedure. The variable direct costs of performing CE MRA and DSA were determined in 20 patients by using detailed time and motion studies. All personnel directly involved in the cases were tracked to the nearest minute and all consumable items used were recorded. Moreover, procedure times were prospectively recorded for an additional 80 patients who underwent both DSA and CE MRA. The variable direct costs of bed usage in the angiography day-case unit, all direct fixed costs as well as indirect costs were assessed from hospital and departmental accounting records. Total costs for each procedure were calculated and compared using Wilcoxon signed-rank sum test. Mean aggregate costs were and euro;721 for DSA and and euro;306 for CE MRA, resulting in potential savings of and euro;415 per patient (p<0.0001). On average, a DSA procedure thus cost approximately 2.4 (95% confidence intervals: 2.2-2.6) times more than CE MRA to our medical institution. Sensitivity analyses confirmed the robustness of our conclusions across wide ranges of plausible values for various parameters. Assuming equal diagnostic performance, institutions may have substantial cost savings if CE MRA is used instead of DSA for carotid imaging. (orig.)

  20. Pulmonary CT angiography: optimization of contrast enhancement technique

    International Nuclear Information System (INIS)

    Ma Lianju; Tang Guangjian; Fu Jiazhen

    2012-01-01

    Objective: To derive and evaluate the formula of exactly calculating the contrast dosage used during pulmonary CT angiography (CTPA). Methods: Time density curves in 27 patients who underwent CTPA were collected and analyzed,the formula for calculating contrast dosage during CTPA was derived. 68 patients suspected of pulmonary embolism (PE) clinically but no PE on CTPA were divided randomly into group A, with bolus tracing technique (n=26), and group B, with small dose injection contrast test (SDCT) (n=42). The CT values of the right main pulmonary artery (RMPA), right upper pulmonary vein (RUPV), right posterior basal PA, right lower PV (RLPV) and the aorta were calculated. The total contrast dosage and the hard beam artifact in the SVC were compared between the two groups.Student's t test, Chi-square test and Mann-Whitney U test were used. Results: The ratio of the time from starting injection to enhancement peak of caudal end of SVC and the time to enhancement peak of the main pulmonary trunk was 0.65 ±0.09 (about 2/3), the formula for contrast dosage calculation was derived as (DTs/3 + STs/2) FR ml/s. The CT values of RMPA and RLPA between the two groups [(301 ±117), (329 ± 122) and (283 ±95), (277 ±98) HU respectively] were not significantly different (t=1.060, P=0.292; t=2.056, P=0.044), but the differences of CT values in the paired PA and PV between the two groups (median were 22.5, 58.0 and 170.5, 166.5 HU respectively) were significant (U=292, P=0.001 and U=325, P=0.005), contrast artifact of the SVC (grade 1-3) in group B (n=34, 7, 1 respectively) was significantly less than in group A (n=11, 10, 5 respectively, χ 2 =10.714, P=0.002), the contrast dosage injected in group A was ( 87.6 ± 7.3) ml, and in group B was (40.0 ±5.4) ml (P<0.01). Conclusion: CTPA with SDCT technique is superior to that with conventional bolus tracing technique regarding contrast dosage and contrast artifact in the SVC. (authors)

  1. Evaluation of three-dimensional contrast-enhanced MR angiography in pediatric body vascular lesions

    International Nuclear Information System (INIS)

    Tanaka, Yasunori; Katayama, Hiroshi; Yamamoto, Kazuhiro; Shimizu, Tadafumi; Narabayashi, Isamu

    1998-01-01

    Evaluation of three-dimensional contrast-enhanced MR angiography in the pediatric body vascular lesions. This study examined the usefulness of three-dimensional gadolinium-enhanced magnetic resonance angiography (3D-enhanced MRA) for pediatric body vascular lesions. Fifteen 3D-enhanced MRAs were performed on fourteen pediatric patients aged from one month to fifteen years, using a 3D fast SPGR sequence. Maximum intensity projection (MIP) and multiplanar reconstruction (MPR) images were obtained from the imaging data in all cases, and eleven MIP images were obtained after subtraction of precontrast-enhanced imaging data from postcontrast-enhanced imaging data. In six cases, MIP and MPR images were correlated with cine or digital subtraction angiographies, and the eleven subtracted MIP images were compared with those before subtraction. Clinical usefulness was demonstrated in fourteen (93%) of the fifteen cases, and in seven (64%) of the eleven cases in which subtraction was performed, image quality was improved. In comparison with cine or digital subtraction angiographies, however, only one (17%) MRA was superior. It was considered that 3D-enhanced MRA was useful for pediatric body vascular lesions because of advantages such as lower invasiveness compared with that of conventional angiography, absence of radiation exposure, safety of contrast media, easy availability of MPR images, and short scanning time. In conclusion, if a pediatric body vascular lesion is suspected, 3D-enhanced MRA should be performed before conventional angiography. It also seems that 3D-enhanced MRA may be useful for follow-up. (author)

  2. Zn-K edge EXAFS study of human nails

    Energy Technology Data Exchange (ETDEWEB)

    Katsikini, M; Mavromati, E; Pinakidou, F; Paloura, E C [School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Gioulekas, D, E-mail: katsiki@auth.g [Medical School, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2009-11-15

    Extended X-ray absorption fine structure (EXAFS) spectroscopy at the Zn - K edge is applied for the study of the bonding geometry of Zn in human nails. The studied nail clippings belong to healthy donors and donors who suffer from lung diseases. Fitting of the first nearest neighboring shell of Zn reveals that it is bonded with N and S, at distances that take values in the ranges 2.00-2.04 A and 2.23-2.28A, respectively. Zn is four - fold coordinated and the ratio of the number of sulfur and nitrogen atoms (N{sub S}/N{sub N}) in the first coordination shell ranges from 0.52 to 1. The sample that belongs to the donor who suffers from lung fibrosis, a condition that is related to keratinization of the lung tissue, is characterized by the highest number of N{sub S}/N{sub N}. Simulation, using the FEFF8 code, of the Zn - K edge EXAFS spectra with models of tetrahedrally coordinated Zn with 1 (or 2) cysteine and 3 (or 2) histidines is satisfactory.

  3. Comparison between fast contrast-enhanced MR angiography and DSA in diagnosing spinal cord vascular malformations

    International Nuclear Information System (INIS)

    Wang Wu; Li Minghua; Fang Chun; Wang Jue; Xiao Yunfeng

    2007-01-01

    Objective: To evaluate the diagnostic and clinical value of fast contrast-enhanced MR angiography (CE-MRA) with elliptic centric phase-encoding in spinal cord vascular malformations. Methods Fast three-dimensional contrast-enhanced MR angiography with elliptic centric phase-encoding and superconducting 1.5T system was applied prospectively in twenty-five consecutive patients with clinically suspected of spinal cord vascular malformations. All cases were performed with selective spinal digital subtraction angiography, including 18 cases treated by surgery and 2 of them with embolization before surgery, MR angiography follow up were undertaken in ten patients after surgery. Comparing fast contrast-enhanced MR angiography with DSA in diagnosing spinal cord vascular malformations included the origin of feeding artery, the feeding artery, the fistula or the nidus, the draining vein, and the vessel image quality based on the gold standard of selective spinal digital subtraction angiography. Results: Surgically proven diseases included spinal arteriovenous malformations(3 cases), spinal cord perimedullary arteriovenous fistulas (5 cases), spinal dural arteriovenous fistulas (8 cases), paravertebral arteriovenous fistulas (1 case), and spontaneous spinal epidural hematomas (2 eases). Comparing with DSA, the accuracy of MR angiography in diagnosing spinal cord vascular malformations; and detecting the origin of the feeding artery, the feeding artery, the shunt or the nidus and the draining vein were 93.8%, 92%, 96.2%, 100% and 100%, respectively. Overall the degree vascular enhencement were judged to be similar(P>0.05), but the vessel continuity of MRA was inferior to DSA (P<0.05). However, 9 cases of MRA showed no abnormal vascular malformation coinciding with those of surgery. Posttreatment MR angiography did not depict any abnormal vessels again. Conclusions: Fast three-dimensional contrast-enhanced MR angiography with elliptic centric phase-encoding may provide

  4. Dynamic contrast-enhanced subtraction MR angiography in intracranial vascular abnormalities

    International Nuclear Information System (INIS)

    Takano, K.; Ono, H.; Utsunomiya, H.; Okazaki, M.; Tanaka, A.

    1999-01-01

    We present our clinical experience with dynamic contrast-enhanced MR angiography (MRA) with subtraction for assessing intracranial vascular abnormalities. Ten patients with various cerebrovascular disorders underwent dynamic contrast-enhanced MRA on a 1.0-T system. Thirty sections (2 mm) were acquired in 29-30 s. Maximum intensity projection images and subtracted source images were compared with those obtained by conventional angiography. In all cases, the presence or absence of abnormalities in the targeted vessels, as well as the morphology of the sagittal sinuses, was clearly visualized as in conventional angiography, without any obstructions such as hyperintense hematomas or thrombi, or intraluminal turbulence. Although the temporal and spatial resolutions with current hardware are insufficient, these preliminary results suggest that dynamic contrast-enhanced MRA with subtraction may be useful for assessing vascular lesions with hemorrhage or thrombus, and the dural sinuses. (orig.)

  5. Evaluation of carotid vessel wall enhancement with image subtraction after gadobenate dimeglumine-enhanced MR angiography

    International Nuclear Information System (INIS)

    Sardanelli, Francesco; Di Leo, Giovanni; Aliprandi, Alberto; Flor, Nicola; Papini, Giacomo D.E.; Roccatagliata, Luca; Cotticelli, Biagio; Nano, Giovanni; Cornalba, Gianpaolo

    2009-01-01

    Objectives: This study was aimed at testing the value of image subtraction for evaluating carotid vessel wall enhancement in contrast-enhanced MR angiography (MRA). Materials and methods: IRB approval was obtained. The scans of 81 consecutive patients who underwent carotid MRA with 0.1 mmol/kg of gadobenate dimeglumine were reviewed. Axial carotid 3D T1-weighted fast low-angle shot sequence before and 3 min after contrast injection were acquired and subtracted (enhanced minus unenhanced). Vessel wall enhancement was assigned a four-point score using native or subtracted images from 0 (no enhancement) to 3 (strong enhancement). Stenosis degree was graded according to NASCET. Results: With native images, vessel wall enhancement was detected in 20/81 patients (25%) and in 20/161 carotids (12%), and scored 2.0 ± 0.6 (mean ± standard deviation); with subtracted images, in 21/81 (26%) and 22/161 (14%), and scored 2.5 ± 0.6, respectively (P < 0.001, Sign test). The overall stenosis degree distribution was: mild, 41/161 (25%); moderate, 77/161 (48%); severe, 43/161 (27%). Carotids with moderate stenosis showed vessel wall enhancement with a frequency (17/77, 22%) significantly higher than that observed in carotids with mild stenosis (1/41, 2%) (P = 0.005, Fisher exact test) and higher, even though with borderline significance (P = 0.078, Fisher exact test), than that observed in carotids with severe stenosis (4/43, 9%). Conclusion: Roughly a quarter of patients undergoing carotid MRA showed vessel wall enhancement. Image subtraction improved vessel wall enhancement conspicuity. Vessel wall enhancement seems to be an event relatively independent from the degree of stenosis. Further studies are warranted to define the relation between vessel wall enhancement and histopathology, inflammatory status, and instability.

  6. Non-contrast enhanced magnetic resonance angiography techniques in candidates for kidney transplantation: A comparative study

    International Nuclear Information System (INIS)

    Blankholm, Anne Dorte; Ginnerup-Pedersen, Bodil; Stausbøl-Grøn, Brian; Haislund, Margit; Laustsen, Sussie; Ringgaard, Steffen

    2013-01-01

    Aim: Detailed knowledge of vessel status in potential candidates for kidney transplantation is essential for the surgeon. Contrast enhanced magnetic resonance angiography has previously been used intensively for assessing this, but the discovery that use of gadolinium based contrast agents in magnetic resonance imaging can cause Nephrogenic Systemic Fibrosis in patients suffering from severe kidney disease has lead to renewed interest in non-contrast enhanced magnetic resonance angiography. The aim of this study was to find a non-contrast enhanced magnetic resonance angiography method for preoperative evaluation of the pelvic vessels prior to kidney transplantation, providing a sufficient image quality. Method: In a prospective study we consecutively included 54 patients undergoing examinations prior to kidney transplantation. The patients were examined with the following magnetic resonance angiography sequences: A 2D Time of flight (n = 54), 3D Time of flight (n = 52) patients, 3D Phase Contrast (n = 54), 3D Balanced Steady State Free Precession (n = 52) and a 2D TRiggered Angiography Non-Contrast Enhanced (TRANCE) (a Spin Echo sequence with subtraction) (n = 48). The sequences were evaluated with respect to contrast, diagnostic performance and artefact burden. Results: Evaluating contrast, 3D Phase Contrast was significantly better than 2D Time of flight (p 0.2). The 2D Time of flight was significantly better than the other sequences (p < 0.001) in all cases. The artefact score was lowest for the Phase Contrast images and significantly superior to the 2D Time of flight (p < 0.005). The 2D Time of flight was significantly better than the three other sequences (p < 0.001) in all cases. Conclusion: Non-contrast enhanced magnetic resonance angiography offers a safe preoperative examination for assessment of vessel status before kidney transplantation. A combination of 2D Time of flight and 3D Phase Contrast acquisitions is recommended and can be performed within a

  7. Portable X-Ray, K-Edge Heavy Metal Detector

    International Nuclear Information System (INIS)

    Fricke, V.

    1999-01-01

    The X-Ray, K-Edge Heavy Metal Detection System was designed and built by Ames Laboratory and the Center for Nondestructive Evaluation at Iowa State University. The system uses a C-frame inspection head with an X-ray tube mounted on one side of the frame and an imaging unit and a high purity germanium detector on the other side. the inspection head is portable and can be easily positioned around ventilation ducts and pipes up to 36 inches in diameter. Wide angle and narrow beam X-ray shots are used to identify the type of holdup material and the amount of the contaminant. Precise assay data can be obtained within minutes of the interrogation. A profile of the containerized holdup material and a permanent record of the measurement are immediately available

  8. Evaluation of the early enhancement of coronary atherosclerotic plaque by contrast-enhanced MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Li Tao [Department of Radiology, The General Hospital of Chinese People' s Armed Police Forces, Number 69, Yong Ding Road, Hai Dian District, Beijing (China); Department of Radiology, Chinese People' s Liberation Army General Hospital, Number 28, Fu Xing Road, Hai Dian District, Beijing (China); Zhao Xihai [Department of Radiology, Chinese People' s Liberation Army General Hospital, Number 28, Fu Xing Road, Hai Dian District, Beijing (China); Liu Xin [Paul C. Lauterbur Biomedical Imaging Center, Institute of Biomedical and Health Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518067 (China); Gao Jianhua [Department of Radiology, The General Hospital of Chinese People' s Armed Police Forces, Number 69, Yong Ding Road, Hai Dian District, Beijing (China); Zhao Shaohong [Department of Radiology, Chinese People' s Liberation Army General Hospital, Number 28, Fu Xing Road, Hai Dian District, Beijing (China); Li Xin; Zhou Weihua [Department of Radiology, The General Hospital of Chinese People' s Armed Police Forces, Number 69, Yong Ding Road, Hai Dian District, Beijing (China); Cai Zulong [Department of Radiology, Chinese People' s Liberation Army General Hospital, Number 28, Fu Xing Road, Hai Dian District, Beijing (China); Zhang Weiguo [Cardiovascular and Neurological Consulting Institute, 6771 San Fernando, Irving, TX 75039 (United States); Yang Li, E-mail: Yangli301@yahoo.com [Department of Radiology, Chinese People' s Liberation Army General Hospital, Number 28, Fu Xing Road, Hai Dian District, Beijing (China)

    2011-10-15

    Purpose: To evaluate the early enhancement of coronary atherosclerotic plaque using contrast-enhanced MR angiography (CE-MRA) and investigate the association between unstable angina pectoris (UAP) and early enhancement of the plaque. Methods: Forty-one patients presenting with angina pectoris and demonstrating single-vessel disease with non-calcified plaque and significant coronary stenosis ({>=}50%) on CTA were consecutively recruited for coronary CE-MRA. Contrast-to-noise ratio of the culprit plaque guided by CTA was measured on a cross-sectional multi-planar reconstruction image of the plaque on both pre- and post-CE-MRA. A 50% increasing of CNR was defined as plaque enhancement. The association between early enhancement of the plaques and UAP was analyzed. Results: Thirty-seven non-calcified plaques with significant coronary stenosis were detected in the 37 patients on MRA. 4 subjects were excluded because coronary atherosclerotic plaques were inadequate for identification on MRA. Of the 37 patients, 18 patients had UAP and other 19 patients presented stable angina pectoris (SAP). Of the 37 plaques on CE-MRA, 13 and 24 plaques presented early enhancement and no enhancement, respectively. Of the 13 early-enhanced plaques, 11 (85%) and 2 (15%) were found in the patients with UAP and SAP, respectively (p < 0.01). Of the 37 patients, 11 (61%) with UAP and 2 (11%) with SAP had early-enhanced plaques, respectively (p < 0.01). Conclusion: CE-MRA allows detection of early enhancement of coronary atherosclerotic plaque. The early enhancement is common in unstable angina and could be a sign of vulnerability.

  9. Contrast-enhanced magnetic resonance angiography: evaluation of renal arteries in living renal transplant donors

    International Nuclear Information System (INIS)

    Firat, Ali; Akin, Oguz; Muhtesem Agildere, Ahmet; Aytekin, Cuneyt; Haberal, Mehmet

    2004-01-01

    One of the most important steps before living-donor nephrectomy is assessment of renal vascular anatomy. The number, origins and lengths of the renal arteries and variations of renal veins must be determined in order to identify the kidney that is most suitable for transplantation. Digital subtraction angiography was long considered the standard procedure for this purpose, but this method has been replaced by non-invasive techniques. Contrast-enhanced magnetic resonance angiography is an accurate, safe and reliable method for imaging vasculature. This article reviews the technique and the clinical features of this method in the evaluation of living renal transplant donors

  10. Contrast-enhanced magnetic resonance angiography: evaluation of renal arteries in living renal transplant donors

    Energy Technology Data Exchange (ETDEWEB)

    Firat, Ali; Akin, Oguz; Muhtesem Agildere, Ahmet; Aytekin, Cuneyt; Haberal, Mehmet

    2004-10-01

    One of the most important steps before living-donor nephrectomy is assessment of renal vascular anatomy. The number, origins and lengths of the renal arteries and variations of renal veins must be determined in order to identify the kidney that is most suitable for transplantation. Digital subtraction angiography was long considered the standard procedure for this purpose, but this method has been replaced by non-invasive techniques. Contrast-enhanced magnetic resonance angiography is an accurate, safe and reliable method for imaging vasculature. This article reviews the technique and the clinical features of this method in the evaluation of living renal transplant donors.

  11. Coronary angiography using synchrotron radiation

    International Nuclear Information System (INIS)

    Akatsuka, Takao; Hiranaka, Yukio; Takeda, Tohru; Hyodo, Kazuyuki.

    1990-01-01

    Invasive coronary angiography is the imaging technique of choice for diagnosis of ischemic heart disease. Recently, the application of synchrotron radiation in coronary angiography has been investigated in the world, with the aim of developing the noninvasive technique for visualizing the heart. In this article, backgrounds and present situation of coronary angiography using synchrotron radiation are reviewed. Firstly, visual imaging techniques of the cardiovascular system are discussed in terms of angiography and digital subtraction angiography (DSA). Conventional temporal, energy, and hybrid subtraction modes used in DSA are referred to. Secondly, the application of synchrotron radiation is presented, focusing on the property of synchrotron radiation and K-edge subtraction angiography. Two kinds of synchrotron radiation beam methods are outlined. Interpretation of image data and various subtraction procedures remain unestablished. There is much to be done before coronary angiography using synchrotron radiation comes into a clinical practice. (N.K.)

  12. Software-triggered contrast-enhanced three-dimensional MR angiography of the intracranial arteries.

    Science.gov (United States)

    Isoda, H; Takehara, Y; Isogai, S; Takeda, H; Tanaka, T; Takahashi, M; Nozaki, A; Sun, Y

    2000-02-01

    We investigated the effectiveness of software-triggered contrast-enhanced three-dimensional (3D) MR angiography in evaluating intracranial arteries. We studied 38 patients with suspected brain lesions. Imaging was performed using a 1.5-T superconducting MR system with a commercially available head coil. To monitor signal intensity changes we used software to place a tracker volume at the basilar artery or the internal carotid artery. A 20-ml bolus of gadodiamide hydrate was administered through the antecubital vein at a rate of 2-4 ml/sec, followed by a saline flush. Three-dimensional MR angiography using a spoiled gradient-echo sequence with centric K-space ordering was triggered by the arrival of the contrast bolus in the tracker volume. Imaging times ranged from 12 to 20 sec. We used MR images to assess the effectiveness of contrast-enhanced 3D MR angiography in revealing intracranial arteries with minimal venous overlap. The software triggered imaging on the arrival of the contrast bolus in 81.6% of examinations. In 77.6% of examinations, the resulting MR angiograms revealed intracranial arteries with minimal venous overlap. Software-triggered contrast-enhanced 3D MR angiography with centric K-space ordering is a promising technique for viewing intracranial arteries.

  13. Blood Pool Contrast-enhanced Magnetic Resonance Angiography with Correlation to Digital Subtraction Angiography: A Pictorial Review

    Directory of Open Access Journals (Sweden)

    Martha-Grace Knuttinen

    2014-01-01

    Full Text Available Magnetic resonance angiography (MRA provides noninvasive visualization of the vascular supply of soft tissue masses and vascular pathology, without harmful radiation. This is important for planning an endovascular intervention, and helps to evaluate the efficiency and effectiveness of the treatment. MRA with conventional extracellular contrast agents relies on accurate contrast bolus timing, limiting the imaging window to first-pass arterial phase. The recently introduced blood pool contrast agent (BPCA, gadofosveset trisodium, reversibly binds to human serum albumin, resulting in increased T1 relaxivity and prolonged intravascular retention time, permitting both first-pass and steady-state phase high-resolution imaging. In our practice, high-quality MRA serves as a detailed "roadmap" for the needed endovascular intervention. Cases of aortoiliac occlusive disease, inferior vena cava thrombus, pelvic congestion syndrome, and lower extremity arteriovenous malformation are discussed in this article. MRA was acquired at 1.5 T with an 8-channel phased array coil after intravenous administration of gadofosveset (0.03 mmol/kg body weight, at the first-pass phase. In the steady-state, serial T1-weighted 3D spoiled gradient echo images were obtained with high resolution. All patients underwent digital subtraction angiography (DSA and endovascular treatment. MRA and DSA findings of vascular anatomy and pathology are discussed and correlated. BPCA-enhanced MRA provides high-quality first-pass and steady-state vascular imaging. This could increase the diagnostic accuracy and create a detailed map for pre-intervention planning. Understanding the pharmacokinetics of BPCA and being familiar with the indications and technique of MRA are important for diagnosis and endovascular intervention.

  14. Generalized Multi-Edge Analysis for K-Edge Densitometry

    International Nuclear Information System (INIS)

    Collins, M.

    1998-01-01

    In K-edge densitometry (KED), a continuous-energy x-ray beam is transmitted through a liquid sample. The actinide content of the sample can be measured through analysis of the transmitted portion of the x-ray beam. Traditional methods for KED analysis allow the simultaneous calculation of, at most, two actinide concentrations. A generalized multi-edge KED analytical method is presented, allowing up to six actinide concentrations to be calculated simultaneously. Applications of this method for hybrid KED/x-ray fluorescence (HKED) systems are discussed. Current HKED systems require the operator to know the approximate actinide content of each sample, and manually select the proper analysis mode. The new multi-edge KED technique allows rapid identification of the major actinide components in a sample, independent of actinide content. The proper HKED analysis mode can be selected automatically, without requiring sample content information from the user. Automatic HKED analysis would be especially useful in an analytical laboratory setting, where samples with truly unknown characteristics are encountered. Because this technique requires no hardware modifications, several facilities that use HKED may eventually benefit from this approach

  15. Sulfur K-edge absorption spectroscopy on selected biological systems

    International Nuclear Information System (INIS)

    Lichtenberg, Henning

    2008-07-01

    Sulfur is an essential element in organisms. In this thesis investigations of sulfur compounds in selected biological systems by XANES (X-ray Absorption Near Edge Structure) spectroscopy are reported. XANES spectroscopy at the sulfur K-edge provides an excellent tool to gain information about the local environments of sulfur atoms in intact biological samples - no extraction processes are required. Spatially resolved measurements using a Kirkpatrick-Baez mirror focusing system were carried out to investigate the infection of wheat leaves by rust fungi. The results give information about changes in the sulfur metabolism of the host induced by the parasite and about the extension of the infection into visibly uninfected plant tissue. Furthermore, XANES spectra of microbial mats from sulfidic caves were measured. These mats are dominated by microbial groups involved in cycling sulfur. Additionally, the influence of sulfate deprivation and H 2 S exposure on sulfur compounds in onion was investigated. To gain an insight into the thermal degradation of organic material the influence of roasting of sulfur compounds in coffee beans was studied. (orig.)

  16. Methods in carbon K-edge NEXAFS: Experiment and analysis

    International Nuclear Information System (INIS)

    Watts, B.; Thomsen, L.; Dastoor, P.C.

    2006-01-01

    Near-edge X-ray absorption spectroscopy (NEXAFS) is widely used to probe the chemistry and structure of surface layers. Moreover, using ultra-high brilliance polarised synchrotron light sources, it is possible to determine the molecular alignment of ultra-thin surface films. However, the quantitative analysis of NEXAFS data is complicated by many experimental factors and, historically, the essential methods of calibration, normalisation and artefact removal are presented in the literature in a somewhat fragmented manner, thus hindering their integrated implementation as well as their further development. This paper outlines a unified, systematic approach to the collection and quantitative analysis of NEXAFS data with a particular focus upon carbon K-edge spectra. As a consequence, we show that current methods neglect several important aspects of the data analysis process, which we address with a combination of novel and adapted techniques. We discuss multiple approaches in solving the issues commonly encountered in the analysis of NEXAFS data, revealing the inherent assumptions of each approach and providing guidelines for assessing their appropriateness in a broad range of experimental situations

  17. Fe K-edge XANES of Maya blue pigment

    Science.gov (United States)

    Río, M. Sánchez del; Sodo, A.; Eeckhout, S. G.; Neisius, T.; Martinetto, P.; Dooryhée, E.; Reyes-Valerio, C.

    2005-08-01

    The utilization of techniques used in Materials Science for the characterization of artefacts of interest for cultural heritage is getting more and more attention nowadays. One of the products of the ancient Maya chemistry is the "Maya blue" pigment, made with natural indigo and palygorskite. This pigment is different from any other pigment used in other parts of the world. It is durable and acid-resistant, and still keeps many secrets to scientists even though it has been studied for more than 50 years. Although the pigment is basically made of palygorskite Si8(Mg2Al2)O20(OH)2(OH2)4.4H2O and an organic colourant (indigo: C16H10N2O2), a number of other compounds have been found in previous studies on archaeological samples, like other clays and minerals, iron nanoparticles, iron oxides, impurities of transition metals (Cr, Mn, Ti, V), etc. We measured at the ESRF ID26 beamline the Fe K-edge XANES spectra of the blue pigment in ancient samples. They are compared to XANES spectra of Maya blue samples synthesized under controlled conditions, and iron oxides usually employed as pigments (hematite and goethite). Our results show that the iron found in ancient Maya blue pigment is related to the Fe exchanged in the palygorskite clay. We did not find iron in metallic form or goethite in archaeological Maya blue.

  18. Fe K-edge XANES of Maya blue pigment

    International Nuclear Information System (INIS)

    Rio, M. Sanchez del; Sodo, A.; Eeckhout, S.G.; Neisius, T.; Martinetto, P.; Dooryhee, E.; Reyes-Valerio, C.

    2005-01-01

    The utilization of techniques used in Materials Science for the characterization of artefacts of interest for cultural heritage is getting more and more attention nowadays. One of the products of the ancient Maya chemistry is the 'Maya blue' pigment, made with natural indigo and palygorskite. This pigment is different from any other pigment used in other parts of the world. It is durable and acid-resistant, and still keeps many secrets to scientists even though it has been studied for more than 50 years. Although the pigment is basically made of palygorskite Si 8 (Mg 2 Al 2 )O 20 (OH) 2 (OH 2 ) 4 .4H 2 O and an organic colourant (indigo: C 16 H 10 N 2 O 2 ), a number of other compounds have been found in previous studies on archaeological samples, like other clays and minerals, iron nanoparticles, iron oxides, impurities of transition metals (Cr, Mn, Ti, V), etc. We measured at the ESRF ID26 beamline the Fe K-edge XANES spectra of the blue pigment in ancient samples. They are compared to XANES spectra of Maya blue samples synthesized under controlled conditions, and iron oxides usually employed as pigments (hematite and goethite). Our results show that the iron found in ancient Maya blue pigment is related to the Fe exchanged in the palygorskite clay. We did not find iron in metallic form or goethite in archaeological Maya blue

  19. Fragmentation of HCl following excitation at the chlorine K edge

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, D.L.; Arrasate, M.E. [Univ. of Nevada, Las Vegas, NV (United States); Cotter, J.P. [Univ. of Nevada, Reno, NV (United States)] [and others

    1997-04-01

    A space-focused time-of-flight (TOF) mass spectrometer was used to study the relaxation dynamics of HCl following excitation in the vicinity of the Cl-K edge ({approximately}2.8 keV) using x-rays from B.L. 9.3.1. At the lowest resonant excitation to a {sigma}{sup *} antibonding orbital (1{sigma} {r_arrow} 6{sigma}), a significant fraction of the excited molecules decay by emission of a neutral H atom. While neutral-H emission has been observed for shallow core levels (e.g., Cl 2p in HCl), the authors believe this to be the first observation of neutral-atom emission as a significant decay channel following resonant excitation of a deep core hole. The dissociation of neutral hydrogen atoms raises the issue of how effectively dissociation competes with Auger decay in the relaxation of these deep core levels (i.e., Cl 1s). Graphical evidence is presented to support the dissociation agrument. In addition, trends in fractional ion yields from Photo-Ion Photo-Ion COincidence (PIPICO) spectra suggest the presence of post-collision interaction (PCI). While, electron spectroscopy studies are required to confirm the observation of this effect, the authors believe this to be the first evidence of PCI moderated dissociation in molecules.

  20. Tungsten anode tubes with K-edge filters for mammography

    Energy Technology Data Exchange (ETDEWEB)

    Beaman, S.; Lillicrap, S.C. (Wessex Regional Medical Physics Service, Bath (UK)); Price, J.L. (Jarvis Screening Centre, Guildford (UK))

    1983-10-01

    Optimum X-ray energies for mammography have previously been calculated using the maximum signal to noise ratio (SNR) per unit dose to the breast, or the minimum exposure for constant SNR. Filters having absorption edges at appropriate energy positions have been used to modify the shape of tungsten anode spectra towards the calculated optimum. The suitability of such spectra for practical use has been assessed by comparing the film image quality and the incident breast dose obtained using a K-edge filtered tungsten anode tube with that obtained using a molybdenum anode. Image quality has been assessed by using a 'random' phantom and by comparing mammograms where one breast was radiographed using a filtered tungsten anode tube and the other using a standard molybdenum anode unit. Relative breast doses were estimated from both ionisation chamber measurements with a phantom and thermoluminescent dosimetry measurements on the breast. Film image quality assessment indicated that the filtered tungsten anode tube gave results not significantly different from those obtained with a molybdenum anode tube for a tissue thickness of about 4 cm and which were better for larger breast thicknesses. Doses could be reduced to between one-half and one-third with the filtered tungsten anode tube.

  1. Tungsten anode tubes with K-edge filters for mammography

    International Nuclear Information System (INIS)

    Beaman, S.; Lillicrap, S.C.; Price, J.L.

    1983-01-01

    Optimum X-ray energies for mammography have previously been calculated using the maximum signal to noise ratio (SNR) per unit dose to the breast, or the minimum exposure for constant SNR. Filters having absorption edges at appropriate energy positions have been used to modify the shape of tungsten anode spectra towards the calculated optimum. The suitability of such spectra for practical use has been assessed by comparing the film image quality and the incident breast dose obtained using a K-edge filtered tungsten anode tube with that obtained using a molybdenum anode. Image quality has been assessed by using a 'random' phantom and by comparing mammograms where one breast was radiographed using a filtered tungsten anode tube and the other using a standard molybdenum anode unit. Relative breast doses were estimated from both ionisation chamber measurements with a phantom and thermoluminescent dosimetry measurements on the breast. Film image quality assessment indicated that the filtered tungsten anode tube gave results not significantly different from those obtained with a molybdenum anode tube for a tissue thickness of abut 4 cm and which were better for larger breast thicknesses. Doses could be reduced to between one-half and one-third with the filtered tungsten anode tube. (U.K.)

  2. Fe K-edge XANES of Maya blue pigment

    Energy Technology Data Exchange (ETDEWEB)

    Rio, M. Sanchez del [ESRF, Experiments Division, B.P. 220, F-38043, Grenoble Cedex (France)]. E-mail: srio@esrf.fr; Sodo, A. [ESRF, Experiments Division, B.P. 220, F-38043, Grenoble Cedex (France); Eeckhout, S.G. [ESRF, Experiments Division, B.P. 220, F-38043, Grenoble Cedex (France); Neisius, T. [ESRF, Experiments Division, B.P. 220, F-38043, Grenoble Cedex (France); Martinetto, P. [Laboratoire de Cristallographie, CNRS, Grenoble B.P. 166, F-38042, Grenoble Cedex 09 (France); Dooryhee, E. [Laboratoire de Cristallographie, CNRS, Grenoble B.P. 166, F-38042, Grenoble Cedex 09 (France); Reyes-Valerio, C. [INAH, Mexico DF (Mexico)

    2005-08-15

    The utilization of techniques used in Materials Science for the characterization of artefacts of interest for cultural heritage is getting more and more attention nowadays. One of the products of the ancient Maya chemistry is the 'Maya blue' pigment, made with natural indigo and palygorskite. This pigment is different from any other pigment used in other parts of the world. It is durable and acid-resistant, and still keeps many secrets to scientists even though it has been studied for more than 50 years. Although the pigment is basically made of palygorskite Si{sub 8}(Mg{sub 2}Al{sub 2})O{sub 20}(OH){sub 2}(OH{sub 2}){sub 4}.4H{sub 2}O and an organic colourant (indigo: C{sub 16}H{sub 10}N{sub 2}O{sub 2}), a number of other compounds have been found in previous studies on archaeological samples, like other clays and minerals, iron nanoparticles, iron oxides, impurities of transition metals (Cr, Mn, Ti, V), etc. We measured at the ESRF ID26 beamline the Fe K-edge XANES spectra of the blue pigment in ancient samples. They are compared to XANES spectra of Maya blue samples synthesized under controlled conditions, and iron oxides usually employed as pigments (hematite and goethite). Our results show that the iron found in ancient Maya blue pigment is related to the Fe exchanged in the palygorskite clay. We did not find iron in metallic form or goethite in archaeological Maya blue.

  3. A comparison between magnetic resonance angiography at 3 teslas (time-of-flight and contrast-enhanced and flat-panel digital subtraction angiography in the assessment of embolized brain aneurysms

    Directory of Open Access Journals (Sweden)

    Guilherme S. Nakiri

    2011-01-01

    Full Text Available PURPOSE: To compare the time-of-flight and contrast-enhanced- magnetic resonance angiography techniques in a 3 Tesla magnetic resonance unit with digital subtraction angiography with the latest flat-panel technology and 3D reconstruction in the evaluation of embolized cerebral aneurysms. INTRODUCTION: Many embolized aneurysms are subject to a recurrence of intra-aneurismal filling. Traditionally, imaging surveillance of coiled aneurysms has consisted of repeated digital subtraction angiography. However, this method has a small but significant risk of neurological complications, and many authors have advocated the use of noninvasive imaging methods for the surveillance of embolized aneurysms. METHODS: Forty-three aneurysms in 30 patients were studied consecutively between November 2009 and May 2010. Two interventional neuroradiologists rated the time-of-flight-magnetic resonance angiography, the contrast-enhanced-magnetic resonance angiography, and finally the digital subtraction angiography, first independently and then in consensus. The status of aneurysm occlusion was assessed according to the Raymond scale, which indicates the level of recanalization according to degrees: Class 1: excluded aneurysm; Class 2: persistence of a residual neck; Class 3: persistence of a residual aneurysm. The agreement among the analyses was assessed by applying the Kappa statistic. RESULTS: Inter-observer agreement was excellent for both methods (K = 0.93; 95 % CI: 0.84-1. Inter-technical agreement was almost perfect between time-of-flight-magnetic resonance angiography and digital subtraction angiography (K = 0.98; 95 % CI: 0.93-1 and between time-of-flight-magnetic resonance angiography and contrast-enhanced-magnetic resonance angiography (K = 0.98; 95% CI: 0.93-1. Disagreement occurred in only one case (2.3%, which was classified as Class I by time-of-flight-magnetic resonance angiography and Class II by digital subtraction angiography. The agreement between

  4. 3D-shaded surface rendering of gadolinium-enhanced MR angiography in congenital heart disease

    International Nuclear Information System (INIS)

    Okuda, S.; Kikinis, R.; Dumanli, H.; Geva, T.; Powell, A.J.; Chung, T.

    2000-01-01

    Background. Gadolinium-enhanced three-dimensional (3D) MR angiography is a useful imaging technique for patients with congenital heart disease. Objective. This study sought to determine the added value of creating 3D shaded surface displays compared to standard maximal intensity projection (MIP) and multiplanar reformatting (MPR) techniques when analyzing 3D MR angiography data. Materials and methods. Seventeen patients (range, 3 months to 51 years old) with a variety of congenital cardiovascular defects underwent gadolinium-enhanced 3D MR angiography of the thorax. Color-coded 3D shaded surface models were rendered from the image data using manual segmentation and computer-based algorithms. Models could be rotated, translocated, or zoomed interactively by the viewer. Information available from the 3D models was compared to analysis based on viewing standard MIP/MPR displays. Results. Median postprocessing time for the 3D models was 6 h (range, 3-25 h) compared to approximately 20 min for MIP/MPR viewing. No additional diagnostic information was gained from 3D model analysis. All major findings with MIP/MPR postprocessing were also apparent on the 3D models. Qualitatively, the 3D models were more easily interpreted and enabled adjacent vessels to be distinguished more readily. Conclusion. Routine use of 3D shaded surface reconstructions for visualization of contrast enhanced MR angiography in congenital heart disease cannot be recommended. 3D surface rendering may be more useful for presenting complex anatomy to an audience unfamiliar with congenital heart disease and as an educational tool. (orig.)

  5. Stability of Working Reference Standards for Hybrid K-Edge Densitometer Quality Assurance

    International Nuclear Information System (INIS)

    Guzzardo, T.; Pickett, C.A.; McElroy, R.; Croft, S.; Garrison, J.; Venkataraman, R.

    2015-01-01

    The relatively short working life of aqueous solution standards of actinides for the calibration and quality control of Hybrid K-Edge Densitometer (HKED) measurements necessitates the development of a stable matrix material less susceptible to degradation. Degradation in the form of evaporation, radiolysis, settling, sloshing, and sediment formation can all reduce the reliability and working life of an aqueous standard. These factors make aqueous solutions inadequate for long-term quality assurance measurements designed to detect weak or subtle trends in system performance. Epoxy, studied here, is an alternative matrix material that may be less vulnerable to degradation. An additional benefit of epoxy is that standards can easily be characterized as sealed sources which allows for simplified administrative controls during shipping and storage. The stability of working reference standards consisting of U 3 O 8 in an epoxy matrix for use in the HKED has been tracked for over three years through repeated X-ray Fluorescence (XRF) and K-Edge (KED) measurements. A set of six epoxy standards ranging in concentration from 1 g/l to 76 g/l uranium were determined to be stable, within the expected accuracy of the system, over the period of analysis. During this time, no effort was made to enhance the stability of the epoxy standards; the radial measurement position was not controlled and in the middle of the analysis period the HKED system and standards were shipped from the vendor's factory to the customer. Epoxy standards afford numerous benefits over those created from aqueous solutions and should be considered when developing HKED standards for quality assurance measurements. The stability of the epoxy allows the development of working standards of a stability and robustness sufficient for use in a proposed international round-robin exercise based on the exchange of such standards. (author)

  6. Prominent porto-systemic collateral pathways in patients with portal hypertension: demonstration by gadolinium-enhanced magnetic resonance angiography

    International Nuclear Information System (INIS)

    Caldana, Rogerio Pedreschi; Bezerra, Alexandre Araujo Sergio; Cecin, Alexnadre Oliveira; Souza, Luis Ronan Marques Ferreira de; Goldman, Susan Menasce; D'Ippolito, Giuseppe; Szejnfeld, Jacob

    2003-01-01

    To demonstrate the usefulness of gadolinium-enhanced magnetic resonance angiography in the evaluation of prominent porto-systemic collateral pathways. We reviewed the images from 40 patients with portal hypertension studied with gadolinium-enhanced magnetic resonance angiography and selected illustrative cases of prominent porto-systemic collateral pathways. The scans were performed using high field equipment (1.5 Tesla) and a 3 D volume technique. Image were obtained after intravenous injection of paramagnetic contrast media using a power injector. Magnetic resonance angiography demonstrated with precision the porto-systemic collateral pathways, particularly when investigating extensive territories or large vessels. The cases presented show the potential of this method in the investigation of patients with portal hypertension. Gadolinium-enhanced magnetic resonance angiography is a useful method for the evaluation of patients with portal hypertension and prominent collateral pathways. (author)

  7. Inflammatory aortic arch syndrome: contrast-enhanced, three-dimensional MR - angiography in stenotic lesions

    International Nuclear Information System (INIS)

    Both, M.; Mueller-Huelsbeck, S.; Biederer, J.; Heller, M.; Reuter, M.

    2004-01-01

    Purpose: To determine the value of contrast-enhanced, three-dimensional MR angiography for the evaluation of stenotic and occlusive vascular lesions in inflammatory aortic arch syndrome. Materials and Methods: 14 patients with inflammatory aortic arch syndrome (giant cell arteritis: n = 8, Takayasu arteritis: n = 4, ankylosing spondylitis: n = 1 sarcoidosis: n = 1) underwent MR angiography of the aortic arch and the supra-aortic vessels (n = 15,2 patients were examined twice) and of the abdominal aorta (n = 2). MRA was performed using a 3D-FLASH sequence (TR/TE 4.6/1.8 ms, flip angle 30 ) on a 1.5T system. MRA imaging was compared with the findings of DSA, which served as gold standard. Results: In a total of 467 examined vascular territories, DSA revealed 50 stenoses and 35 occlusions. All lesions were detected by MRA. In 23 segments, the degree of stenosis was overestimated by MRA. Sensitivity and specificity of MRA were 100% and 94,3%, positive and negative predictive values were 73.6 and 100%, and the accuracy was 95,1%. Conclusions: Despite a tendency to overestimate stenoses, contrast-enhanced three-dimensional MR angiography is a valid, non-invasive technique in the assessment of inflammatory aortic arch syndrome. (orig.) [de

  8. Clinical application of gadolinium-enhanced three-dimensional pulmonary MR angiography

    International Nuclear Information System (INIS)

    Takano, Katsuyuki

    1999-01-01

    Twenty-nine patients with suspected pulmonary lesions, and three normal volunteers, underwent gadolinium-enhanced three-dimensional (3D) pulmonary MR angiography (MRA). The MRA were obtained during intravenous administration of gadolinium-based contrast material, in a single breath-hold. Conspicuity of the normal pulmonary segmental arteries was estimated on the MRA. Abnormal findings such as ''vascular involvement'', ''abnormal connection'', stenosis'', or ''dilatation'' on the MRA were compared with those on conventional angiography or CT. Normal pulmonary segmental arteries, except for A 4,5,6,8and9 of the left pulmonary artery, could be clearly visualized. Blind reading of four different findings lead to characteristic findings for each pulmonary disease that can be aid in their differential diagnoses. This technique shows promise as a noninvasive diagnosis of lung diseases. (author)

  9. CT angiography. Abdominal CT using intravenous aortography for contrast enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, J; Nakauma, Y; Egawa, J; Kawamura, M [Teikyo Univ., Tokyo (Japan). Faculty of Medicine

    1980-04-01

    To obtain imaging effects close to those of abdominal aortography and investigate a technique with little invasion to patients, intravenous aortography was applied to contrast enhancement (CE) in abdominal CT, and its usefulness was discussed. Intravenous aortography could clearly visualize lesions with rich neovascularity such as hepatocellular carcinoma and renal cell carcinoma. Differing from a drip infusion method, this method has complexities in its technique that contrast medium is injected at once, blood circulation time which is represented by the time between the injection and the time when the patients feel bitterness (10 - 12 seconds) must be measured before CE, and scanning begins 2 seconds before the patients feel bitterness. However, the invasion to patients due to this method is slight, and the capacity of this method to visualize neovascularity is superior to CE by a drip infusion method. Therefore, qualitative diagnosis by CT will be improved by using this method together with a drip infusion method.

  10. Strong excitonic interactions in the oxygen K-edge of perovskite oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tomita, Kota; Miyata, Tomohiro [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Olovsson, Weine [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Mizoguchi, Teruyasu, E-mail: teru@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan)

    2017-07-15

    Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO{sub 3}, SrTiO{sub 3}, and BaTiO{sub 3}, together with reference oxides, MgO, CaO, SrO, BaO, and TiO{sub 2}, were investigated using a first-principles Bethe–Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti–O–Ti bonds. - Highlights: • Excitonic interaction in oxygen-K edge is investigated. • Strong excitonic interaction is found in the oxygen-K edge of perovskite oxides. • The strong excitonic interaction is ascribed to the low-dimensional and confined electronic structure.

  11. Gadolinium-enhanced magnetic resonance angiography in neonates and infants suspected of caval or aortic thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Greenberg, S. Bruce; Bhutta, Sadaf T.; Buchmann, Robert F. [University of Arkansas for Medical Sciences, Arkansas Children' s Hospital, Little Rock, AR (United States)

    2004-12-01

    Gadolinium-enhanced magnetic resonance angiography (MRA)is a well-established technique in older children and adults. No studies have focused on its use in neonates and small infants. Our objective was to study the use of gadolinium-enhanced MRA in neonates and infants suspected of caval or aortic thrombosis. Materials and Methods:Gadolinium-enhanced MR angiography was performed on seven neonates and small infants for the evaluation of caval or aortic thrombosis. Gadolinium-DTPA at a dose of 0.3 mmol/kg (minimum dose 1 ml) was injected using a power injector (0.2 ml/s). Contrast-enhanced MRA was performed using a 3-D, fast, radiofrequency spoiled gradient-echo sequence (TR/TE: 4.8/1.1, flip angle 45 , matrix 256 x 128, slice thickness 2.6 mm interpolated to 1.3 mm, FOV variable, NEX=1.0). Diagnostic-quality angiograms were obtained in all seven neonates. Superior vena cava thrombosis was identified in two neonates, and abdominal aortic thrombosis was present in one neonate. It is practical to perform gadolinium-enhanced MRA in neonates weighing as little as 600 g for the detection of caval or aortic thrombosis. (orig.)

  12. Gadolinium-enhanced magnetic resonance angiography in neonates and infants suspected of caval or aortic thrombosis

    International Nuclear Information System (INIS)

    Greenberg, S. Bruce; Bhutta, Sadaf T.; Buchmann, Robert F.

    2004-01-01

    Gadolinium-enhanced magnetic resonance angiography (MRA)is a well-established technique in older children and adults. No studies have focused on its use in neonates and small infants. Our objective was to study the use of gadolinium-enhanced MRA in neonates and infants suspected of caval or aortic thrombosis. Materials and Methods:Gadolinium-enhanced MR angiography was performed on seven neonates and small infants for the evaluation of caval or aortic thrombosis. Gadolinium-DTPA at a dose of 0.3 mmol/kg (minimum dose 1 ml) was injected using a power injector (0.2 ml/s). Contrast-enhanced MRA was performed using a 3-D, fast, radiofrequency spoiled gradient-echo sequence (TR/TE: 4.8/1.1, flip angle 45 , matrix 256 x 128, slice thickness 2.6 mm interpolated to 1.3 mm, FOV variable, NEX=1.0). Diagnostic-quality angiograms were obtained in all seven neonates. Superior vena cava thrombosis was identified in two neonates, and abdominal aortic thrombosis was present in one neonate. It is practical to perform gadolinium-enhanced MRA in neonates weighing as little as 600 g for the detection of caval or aortic thrombosis. (orig.)

  13. Photoabsorption spectra of potassium and rubidium near the K-edge

    International Nuclear Information System (INIS)

    Azuma, Y.; Berry, H.G.; Cowan, P.L.

    1995-01-01

    We have used a high-temperature circulating heat-pipe absorption cell together with monochromatized X-ray beams at the X24A and X23A2 beam lines at the NSLS to obtain photoabsorption spectra of potassium and rubidium at their K- and KM-edges. The photon-energy ranges lay near 3600 eV and 15200 eV, respectively. We have also obtained first measurements of the LII and LIII edges in cesium. Although the K-edge photoabsorptions of the rare gases have been studied, there is little previous work on other atomic vapors. Most of the edges and resonance peaks that we observed have now been identified using Dirac Hartree-Fock calculations. As a check, we have compared these results with those obtained previously in closed-shell rare-gas absorption spectra. The absolute energies were obtained through a calibration of the X24A systems using measurements of several metal L-edges in the 3200-5000 eV energy range. We found that the 4p resonance in potassium is significantly enhanced compared with the corresponding situation in argon. Likewise, the 5p resonance in krypton is unresolved from the background ionization cross section, whereas it is well resolved in rubidium. As suggested by Amusia, these enhancements may be due to the enhanced potential seen in the excited state of the alkali systems as a result of the presence of an s-electron which reduces the nuclear shielding

  14. Application of X-ray K-edge densitometry in D and D operations

    International Nuclear Information System (INIS)

    Jensen, T.; Aljundi, T.; Gray, J.N.; Iowa State Univ., Ames, IA

    1998-01-01

    K-edge densitometry is a nondestructive assay technique which provides accurate measurement of heavy metal contamination in pipes, containers, and other items encountered in D and D operations. A prototype mobile K-edge instrument has been built and demonstrated in several applications. Results from measurements of uranium in pipes and spent reactor fuel plates, and quantification of mercury and lead in waste drums are presented. In this report the authors briefly describe the theory behind K-edge densitometry. They follow that with a description of the prototype system they have developed, and a presentation of results from demonstrations of this system. They conclude with a discussion of the potential for application of K-edge analysis in D and D operations

  15. Diagnosis of the hypothenar hammer syndrome by high-resolution contrast-enhanced MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Winterer, J.T.; Ghanem, N.; Schaefer, O.; Lehnhardt, S.; Thuerl, C.; Laubenberger, J. [Department of Diagnostic Radiology, University of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany); Roth, M. [Center of Geriatric Medicine and Gerontology Freiburg, University of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany); Horch, R.E. [Department of Plastic and Hand Surgery, University of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany)

    2002-10-01

    Our objective was to describe the imaging features of hypothenar hammer syndrome using minimally invasive contrast-enhanced MR angiography in comparison with oscillography study. In five patients with hypothenar hammer syndrome Gd-BOPTA-enhanced elliptically reordered 3D pulse sequence MR was compared with oscillography findings and clinical symptoms focusing on angiographic appearance of vessel injury, distribution pattern of hand vasculature and joining branches between the radial and ulnar artery supply. All patients showed segmental occlusion at the site of trauma impact with varying involvement of the superficial palmar arch, common volar digital arteries. Embolic disease was present in 50% of patients and could be clearly identified with MRA. Good correspondence was found between angiographic appearance including the presence of collaterals, clinical symptoms and oscillography. Bilateral comparison was helpful in distinguishing between vessel variants and pathology. Bilateral Gd-BOPTA-enhanced MR angiography is a minimally invasive method to depict clearly the localization and extent of vessel injury in hypothenar hammer syndrome providing valuable information about distribution pattern of hand vasculature and presence of collaterals; however, no flow data can be obtained. (orig.)

  16. Enhanced MR angiography of the lower extremities with synergy spine coil

    International Nuclear Information System (INIS)

    Takashima, Hiroyuki; Watanabe, Naoki

    2002-01-01

    A synergy spine coil is a phased-array coil designed for spine imaging. The coil's sensitive area is narrow in both the x-axis and y-axis directions but very wide in the z-axis direction. It is therefore suitable for using in long parts of the body, such as the spine. We used the coil for enhanced MR angiography in the lower extremities, which requires a very long field of view on the z-axis direction. Using on the NEMA (National Electrical Manufacturers Association) standard test for special-purpose coils, the sensitive volume of the synergy spine coil was first measured by using a phantom. It was found that the sensitive lengths along x-axis and y-axis were 300 mm and 120 mm, respectively, while that along z-axis could set at any length required for the examination by modifying the element number. The above area was confirmed to be sufficient for obtaining enhanced MR angiograms of the lower extremities. The results of this study showed the use of the synergy spine coil in enhanced MR angiography of the lower extremities is superior to the use of a conventional whole body coil for obtaining good MR angiograms with a good single-to-noise ratio (SNR). (author)

  17. Diagnosis of the hypothenar hammer syndrome by high-resolution contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Winterer, J.T.; Ghanem, N.; Schaefer, O.; Lehnhardt, S.; Thuerl, C.; Laubenberger, J.; Roth, M.; Horch, R.E.

    2002-01-01

    Our objective was to describe the imaging features of hypothenar hammer syndrome using minimally invasive contrast-enhanced MR angiography in comparison with oscillography study. In five patients with hypothenar hammer syndrome Gd-BOPTA-enhanced elliptically reordered 3D pulse sequence MR was compared with oscillography findings and clinical symptoms focusing on angiographic appearance of vessel injury, distribution pattern of hand vasculature and joining branches between the radial and ulnar artery supply. All patients showed segmental occlusion at the site of trauma impact with varying involvement of the superficial palmar arch, common volar digital arteries. Embolic disease was present in 50% of patients and could be clearly identified with MRA. Good correspondence was found between angiographic appearance including the presence of collaterals, clinical symptoms and oscillography. Bilateral comparison was helpful in distinguishing between vessel variants and pathology. Bilateral Gd-BOPTA-enhanced MR angiography is a minimally invasive method to depict clearly the localization and extent of vessel injury in hypothenar hammer syndrome providing valuable information about distribution pattern of hand vasculature and presence of collaterals; however, no flow data can be obtained. (orig.)

  18. Catheter Angiography

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Catheter Angiography Catheter angiography uses a catheter, x-ray ... are the limitations of Catheter Angiography? What is Catheter Angiography? Angiography is a minimally invasive medical test ...

  19. Diagnostic accuracy of contrast-enhanced MR angiography and unenhanced proton MR imaging compared with CT pulmonary angiography in chronic thromboembolic pulmonary hypertension

    Energy Technology Data Exchange (ETDEWEB)

    Rajaram, Smitha [Unit of Academic Radiology, University of Sheffield, Sheffield (United Kingdom); Academic Unit of Radiology, C Floor, Royal Hallamshire Hospital, Sheffield (United Kingdom); Swift, Andrew J.; Wild, Jim M. [Unit of Academic Radiology, University of Sheffield, Sheffield (United Kingdom); Sheffield Cardiovascular Biomedical Research Unit, Sheffield (United Kingdom); Capener, David; Telfer, Adam [Unit of Academic Radiology, University of Sheffield, Sheffield (United Kingdom); Davies, Christine; Hill, Catherine [Sheffield Teaching Hospitals Trust, Department of Radiology, Sheffield (United Kingdom); Condliffe, Robin; Elliot, Charles; Kiely, David G. [Sheffield Pulmonary Vascular Disease Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield (United Kingdom); Sheffield Cardiovascular Biomedical Research Unit, Sheffield (United Kingdom); Hurdman, Judith [Sheffield Pulmonary Vascular Disease Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield (United Kingdom)

    2012-02-15

    To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) and the added benefit of unenhanced proton MR angiography compared with CT pulmonary angiography (CTPA) in patients with chronic thromboembolic disease (CTE). A 2 year retrospective study of 53 patients with chronic thromboembolic pulmonary hypertension who underwent CTPA and MRI for suspected pulmonary hypertension and a control group of 36 patients with no CT evidence of pulmonary embolism. The MRI was evaluated for CTE and the combined diagnostic accuracy of ce-MRA and unenhanced proton MRA was determined. CE-MRA generated lung perfusion maps were also assessed. The overall sensitivity and specificity of CE-MRA in diagnosing proximal and distal CTE were 98% and 94%, respectively. The sensitivity improved from 50% to 88% for central vessel disease when CE-MRA images were analysed with unenhanced proton MRA. The CE-MRA identified more stenoses (29/18), post-stenosis dilatation (23/7) and occlusions (37/29) compared with CTPA. The CE-MRA perfusion images showed a sensitivity of 92% for diagnosing CTE. CE-MRA has high sensitivity and specificity for diagnosing CTE. The sensitivity of CE-MRA for visualisation of adherent central and lobar thrombus significantly improves with the addition of unenhanced proton MRA which delineates the vessel wall. (orig.)

  20. Diagnostic accuracy of contrast-enhanced MR angiography and unenhanced proton MR imaging compared with CT pulmonary angiography in chronic thromboembolic pulmonary hypertension

    International Nuclear Information System (INIS)

    Rajaram, Smitha; Swift, Andrew J.; Wild, Jim M.; Capener, David; Telfer, Adam; Davies, Christine; Hill, Catherine; Condliffe, Robin; Elliot, Charles; Kiely, David G.; Hurdman, Judith

    2012-01-01

    To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) and the added benefit of unenhanced proton MR angiography compared with CT pulmonary angiography (CTPA) in patients with chronic thromboembolic disease (CTE). A 2 year retrospective study of 53 patients with chronic thromboembolic pulmonary hypertension who underwent CTPA and MRI for suspected pulmonary hypertension and a control group of 36 patients with no CT evidence of pulmonary embolism. The MRI was evaluated for CTE and the combined diagnostic accuracy of ce-MRA and unenhanced proton MRA was determined. CE-MRA generated lung perfusion maps were also assessed. The overall sensitivity and specificity of CE-MRA in diagnosing proximal and distal CTE were 98% and 94%, respectively. The sensitivity improved from 50% to 88% for central vessel disease when CE-MRA images were analysed with unenhanced proton MRA. The CE-MRA identified more stenoses (29/18), post-stenosis dilatation (23/7) and occlusions (37/29) compared with CTPA. The CE-MRA perfusion images showed a sensitivity of 92% for diagnosing CTE. CE-MRA has high sensitivity and specificity for diagnosing CTE. The sensitivity of CE-MRA for visualisation of adherent central and lobar thrombus significantly improves with the addition of unenhanced proton MRA which delineates the vessel wall. (orig.)

  1. Value of contrast-enhanced 3D MR angiography of the renal arteries

    International Nuclear Information System (INIS)

    Hany, T.F.; Pfammatter, T.; Schmidt, M.; Leung, D.A.; Debatin, J.F.

    1997-01-01

    Purpose: To determine the value of gadolinium-enhanced, three-dimensional breath-hold Magnetic Resonance Angiography (MRA) in the assessment of the aorta and renal arteries in comparison to conventional arteriography (CA). Patients and methods: 49 patients were evaluated with both CA and 3D MRA. 0.3 mmol/kg BW gadolinium-DTPA was administered intravenously in a bolus, using an automated injector. A test bolus method was used for timing of the bolus and beginning of the data acquisition. The intraaterial CA was used as the gold standard. Results: MRA-based assessment of renal artery stenosis was identical with CA in 31 of 45 stenoses (68.8%). Senstivity and specificity for assessment of renal arterial disease by MRA were 84% and 96%; for clinically relevant lesions they amounted to 90% and 98%. Conclusion: The presented contrast-enhanced 3D MRA technique allows for the reliable assessment of renal arterial morphology and pathology. (orig.) [de

  2. Strong excitonic interactions in the oxygen K-edge of perovskite oxides.

    Science.gov (United States)

    Tomita, Kota; Miyata, Tomohiro; Olovsson, Weine; Mizoguchi, Teruyasu

    2017-07-01

    Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO 3 , SrTiO 3 , and BaTiO 3 , together with reference oxides, MgO, CaO, SrO, BaO, and TiO 2 , were investigated using a first-principles Bethe-Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti-O-Ti bonds. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Renal contrast-enhanced MR angiography: timing errors and accurate depiction of renal artery origins.

    Science.gov (United States)

    Schmidt, Maria A; Morgan, Robert

    2008-10-01

    To investigate bolus timing artifacts that impair depiction of renal arteries at contrast material-enhanced magnetic resonance (MR) angiography and to determine the effect of contrast agent infusion rates on artifact generation. Renal contrast-enhanced MR angiography was simulated for a variety of infusion schemes, assuming both correct and incorrect timing between data acquisition and contrast agent injection. In addition, the ethics committee approved the retrospective evaluation of clinical breath-hold renal contrast-enhanced MR angiographic studies obtained with automated detection of contrast agent arrival. Twenty-two studies were evaluated for their ability to depict the origin of renal arteries in patent vessels and for any signs of timing errors. Simulations showed that a completely artifactual stenosis or an artifactual overestimation of an existing stenosis at the renal artery origin can be caused by timing errors of the order of 5 seconds in examinations performed with contrast agent infusion rates compatible with or higher than those of hand injections. Lower infusion rates make the studies more likely to accurately depict the origin of the renal arteries. In approximately one-third of all clinical examinations, different contrast agent uptake rates were detected on the left and right sides of the body, and thus allowed us to confirm that it is often impossible to optimize depiction of both renal arteries. In three renal arteries, a signal void was found at the origin in a patent vessel, and delayed contrast agent arrival was confirmed. Computer simulations and clinical examinations showed that timing errors impair the accurate depiction of renal artery origins. (c) RSNA, 2008.

  4. X-ray K-edge analysis of drain lines in Wilhelm Hall, Ames Laboratory

    International Nuclear Information System (INIS)

    Jensen, T.; Whitmore, C.; Iowa State Univ., Ames, IA

    1999-01-01

    From August 12--27, 1998 X-ray K-edge measurements were made on drain lines in seven rooms in Wilhelm Hall, Ames Laboratory. The purpose of these measurements was to determine the extent of thorium (and other heavy metal) contamination inside these pipes. The K-edge method is a noninvasive inspection technique that can provide accurate quantification of heavy metal contamination interior to an object. Of the seven drain lines inspected, one was found to have no significant contamination, three showed significant thorium deposits, two showed mercury contamination, and one line was found to contain mercury, thorium and uranium. The K-edge measurements were found to be consistent with readings from hand-held survey meters, and provided much greater detail on the location and amount of heavy metal contamination

  5. The optimization of scan timing for contrast-enhanced magnetic resonance angiography

    International Nuclear Information System (INIS)

    Lee, Jong Min; Chang, Yong Min; Ryeom, Hun Kyu; Lee, Sang Kwon; Kim, Yong Sun; Kang, Duk Sik; Tirman, Philip J.

    2000-01-01

    To determine the optimal scan timing for contrast-enhanced magnetic resonance angiography and to evaluate a new timing method based on the arteriovenous circulation time. Eighty-nine contrast-enhanced magnetic resonance angiographic examinations were performed mainly in the extremities. A 1.5T scanner with a 3-D turbo-FLASH sequence was used, and during each study, two consecutive arterial phases and one venous phase were acquired. Scan delay time was calculated from the time-intensity curve by the traditional (n = 48) and/or the new (n = 41) method. This latter was based on arteriovenous circulation time rather than peak arterial enhancement time, as used in the traditional method. The numbers of first-phase images showing a properly enhanced arterial phase were compared between the two methods. Mean scan delay time was 5.4 sec longer with the new method than with the traditional. Properly enhanced first-phase images were found in 65% of cases (31/48) using the traditional timing method, and 95% (39/41) using the new method. When cases in which there was mismatch between the target vessel and the Time-intensity curve acquisition site are excluded, erroneous acquisition occurred in seven cases with the traditional method, but in none with the new method. The calculation of scan delay time on the basis of arteriovenous circulation time provides better timing for arterial phase acquisition than the traditional method

  6. Contrast-enhanced MR 3D angiography in the assessment of brain AVMs

    International Nuclear Information System (INIS)

    Unlu, Ercument; Temizoz, Osman; Albayram, Sait; Genchellac, Hakan; Hamamcioglu, M. Kemal; Kurt, Imran; Demir, M. Kemal

    2006-01-01

    Background and purpose: Digital subtraction angiography (DSA) is the current reference standard for the diagnosis, assessment, and management of brain arteriovenous malformations (AVMs). The purpose of this study was to compare the diagnostic utility of three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) and contrast-enhanced 3D MRA in patients with intracranial arteriovenous malformations (AVMs) in different sizes and locations. The AVM diagnosis was proved via DSA and almost half of the patients had also hematoma. Materials and methods: Two radiologists, experienced on neurovascular imaging and independent from each other, retrospectively reviewed two MRA techniques and DSA with regard to the assessment of feeding arteries, AVM nidus, and venous drainage patterns on 20 patients with 23 examinations by scoring system. Disagreements were resolved by consensus. Results: An excellent agreement between contrast-enhanced MRA and DSA was found in order to assess the numbers of arterial feeders and draining veins (Spearman r = 0.913, P < 0.001). The average scores in contrast-enhanced MRA for feeders, nidi, and drainers were respectively 2.26, 2.69, and 2.48, while in TOF-MRA they are 1.96, 1.35, and 0.89, respectively. Conclusion: Compared to TOF-MRA, 3D contrast-enhanced MRA is useful for visualization by subtraction technique of malformation components presented by hematoma or by haem product. On the other hand, for the cases presented by slow or complex flow that is especially in around or nidi or around the venous portion is also advantageous because of the independence from flow-related enhancement. Therapeutic effects were clearly demonstrated in three follow-up patients. A major limitation of this technique is the low spatial resolution. Since there is such a limitation, arterial feeder of a case with micro-AVM is not detected by contrast-enhanced MRA and nidus for the same case was observed retrospectively. In this respect, we

  7. Contrast-enhanced MR 3D angiography in the assessment of brain AVMs

    Energy Technology Data Exchange (ETDEWEB)

    Unlu, Ercument [Department of Radiology, Trakya University Medicine School, Edirne (Turkey)]. E-mail: drercument@yahoo.com; Temizoz, Osman [Department of Radiology, Trakya University Medicine School, Edirne (Turkey); Albayram, Sait [Department of Radiology, Istanbul University, Cerrahpasa Medicine School, Istanbul (Turkey); Genchellac, Hakan [Department of Radiology, Trakya University Medicine School, Edirne (Turkey); Hamamcioglu, M. Kemal [Department of Neurosurgery, Trakya University Medicine School, Edirne (Turkey); Kurt, Imran [Department of Biostatistics, Trakya University Medicine School, Edirne (Turkey); Demir, M. Kemal [Department of Radiology, Trakya University Medicine School, Edirne (Turkey)

    2006-12-15

    Background and purpose: Digital subtraction angiography (DSA) is the current reference standard for the diagnosis, assessment, and management of brain arteriovenous malformations (AVMs). The purpose of this study was to compare the diagnostic utility of three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) and contrast-enhanced 3D MRA in patients with intracranial arteriovenous malformations (AVMs) in different sizes and locations. The AVM diagnosis was proved via DSA and almost half of the patients had also hematoma. Materials and methods: Two radiologists, experienced on neurovascular imaging and independent from each other, retrospectively reviewed two MRA techniques and DSA with regard to the assessment of feeding arteries, AVM nidus, and venous drainage patterns on 20 patients with 23 examinations by scoring system. Disagreements were resolved by consensus. Results: An excellent agreement between contrast-enhanced MRA and DSA was found in order to assess the numbers of arterial feeders and draining veins (Spearman r = 0.913, P < 0.001). The average scores in contrast-enhanced MRA for feeders, nidi, and drainers were respectively 2.26, 2.69, and 2.48, while in TOF-MRA they are 1.96, 1.35, and 0.89, respectively. Conclusion: Compared to TOF-MRA, 3D contrast-enhanced MRA is useful for visualization by subtraction technique of malformation components presented by hematoma or by haem product. On the other hand, for the cases presented by slow or complex flow that is especially in around or nidi or around the venous portion is also advantageous because of the independence from flow-related enhancement. Therapeutic effects were clearly demonstrated in three follow-up patients. A major limitation of this technique is the low spatial resolution. Since there is such a limitation, arterial feeder of a case with micro-AVM is not detected by contrast-enhanced MRA and nidus for the same case was observed retrospectively. In this respect, we

  8. Theoretical Mn K-edge XANES for Li2MnO3: DFT + U study

    International Nuclear Information System (INIS)

    Tamura, Tomoyuki; Ohwaki, Tsukuru; Ito, Atsushi; Ohsawa, Yasuhiko; Kobayashi, Ryo; Ogata, Shuji

    2012-01-01

    Spectral features of Mn K-edge x-ray absorption near-edge structure (XANES) for Li 2 MnO 3 were calculated using the first-principles full projector augmented wave method with the general gradient approximation plus U method. We demonstrated that the U parameter affects the spectral features in the pre-edge region while it does not affect those in the major absorption region. From the comparison with the experimental spectra and those of reference compounds, we showed that the spectral features of Mn K-edge XANES and the differences in the valence state can be reproduced well. (paper)

  9. Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect.

    Science.gov (United States)

    Napolitano, Mary E; Trueblood, Jon H; Hertel, Nolan E; David, George

    2002-09-01

    A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within +/-1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine

  10. Image reconstruction for x-ray K-edge imaging with a photon counting detector

    Science.gov (United States)

    Meng, Bo; Cong, Wenxiang; Xi, Yan; Wang, Ge

    2014-09-01

    Contrast agents with high-Z elements have K-absorption edges which significantly change X-ray attenuation coefficients. The K-edge characteristics is different for various kinds of contrast agents, which offers opportunities for material decomposition in biomedical applications. In this paper, we propose a new K-edge imaging method, which not only quantifies a distribution of a contrast agent but also provides an optimized contrast ratio. Our numerical simulation tests demonstrate the feasibility and merits of the proposed methodology.

  11. Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect

    International Nuclear Information System (INIS)

    Napolitano, Mary E.; Trueblood, Jon H.; Hertel, Nolan E.; David, George

    2002-01-01

    A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within ±1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine

  12. Plutonium isotopic assay of reprocessing product solutions in the KfK K-edge densitometer

    International Nuclear Information System (INIS)

    Eberle, H.; Ottmar, H.; Matussek, P.

    1985-04-01

    The KfK K-edge densiometer, designed for accurate element concentration measurements using the technique of X-ray absorptiometry at the K absorption edge, provides as an additional option the possibility to determine the isotopic composition of freshly separated plutonium from an gamma-spectrometric analysis of its self-radiation. This report describes the underlying methodology and experimental procedures for the isotopic analysis in the K-edge densitometer. The paper also presents and discusses the experimental results so far obtained from routine measurements on reprocessing product solutions. (orig.)

  13. Ferumoxytol-enhanced magnetic resonance angiography for the assessment of potential kidney transplant recipients

    Energy Technology Data Exchange (ETDEWEB)

    Stoumpos, Sokratis; Mark, Patrick B. [Queen Elizabeth University Hospital, Renal and Transplant Unit, Glasgow (United Kingdom); University of Glasgow, Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, Glasgow (United Kingdom); Hennessy, Martin; Kasthuri, Ram; Roditi, Giles [Queen Elizabeth University Hospital, Department of Radiology, Glasgow (United Kingdom); Vesey, Alex T.; Kingsmore, David B. [Queen Elizabeth University Hospital, Renal and Transplant Unit, Glasgow (United Kingdom); Radjenovic, Aleksandra [University of Glasgow, Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, Glasgow (United Kingdom)

    2018-01-15

    Traditional contrast-enhanced methods for scanning blood vessels using magnetic resonance imaging (MRI) or CT carry potential risks for patients with advanced kidney disease. Ferumoxytol is a superparamagnetic iron oxide nanoparticle preparation that has potential as an MRI contrast agent in assessing the vasculature. Twenty patients with advanced kidney disease requiring aorto-iliac vascular imaging as part of pre-operative kidney transplant candidacy assessment underwent ferumoxytol-enhanced magnetic resonance angiography (FeMRA) between December 2015 and August 2016. All scans were performed for clinical indications where standard imaging techniques were deemed potentially harmful or inconclusive. Image quality was evaluated for both arterial and venous compartments. First-pass and steady-state FeMRA using incremental doses of up to 4 mg/kg body weight of ferumoxytol as intravenous contrast agent for vascular enhancement was performed. Good arterial and venous enhancements were achieved, and FeMRA was not limited by calcification in assessing the arterial lumen. The scans were diagnostic and all patients completed their studies without adverse events. Our preliminary experience supports the feasibility and utility of FeMRA for vascular imaging in patients with advanced kidney disease due for transplant listing, which has the advantages of obtaining both arteriography and venography using a single test without nephrotoxicity. (orig.)

  14. Carotid Artery Stenosis: Comparison of 3D Time-of-Flight MR Angiography and Contrast-Enhanced MR Angiography at 3T

    Directory of Open Access Journals (Sweden)

    Ivan Platzek

    2014-01-01

    Full Text Available Purpose. The aim of this study was to assess the correlation of 3D time-of-flight MR angiography (TOF MRA and contrast-enhanced MR angiography (CEMRA for carotid artery stenosis evaluation at 3T. Material and Methods. Twenty-three patients (5 f, 18 m; mean age 61 y, age range 45–78 y with internal carotid artery stenosis detected with ultrasonography were examined on a 3.0T MR system. The MR examination included both 3D TOF MRA and CEMRA of the carotid arteries. MR images were evaluated independently by two board-certified radiologists. Stenosis evaluation was based on a five-point scale. Stenosis grades determined by TOF and CEMRA were compared using Spearman’s rank correlation coefficient and the Wilcoxon test. Cohen’s Kappa was used to evaluate interrater reliability. Results. CEMRA detected stenosis in 24 (52% of 46 carotids evaluated, while TOF detected stenosis in 27 (59% of 46 carotids. TOF MRA yielded significantly higher results for stenosis grade in comparison to CEMRA (P=0.014. Interrater agreement was very good for both TOF MRA (κ=0.93 and CEMRA (κ=0.93. Conclusion. At 3T, 3D TOF MRA should not be used as replacement for contrast-enhanced MRA of the carotid arteries, as it results in significantly higher stenosis grades.

  15. Contrast-enhanced thoracic 3D-MR angiography in infants and children

    International Nuclear Information System (INIS)

    Holmqvist, C.; Larsson, E.M.; Staahlberg, F.; Laurin, S.

    2000-01-01

    To optimise breath-hold contrast-enhanced MR angiography (MRA) in infants and children with suspected congenital heart or thoracic vessel malformation. Thirty-nine children (median age 1 year) were examined, using five different ultrafast MRA sequences with a TR between 3.2 and 5.0 ms and the contrast agent meglumine gadoterate. A test injection was used to determine contrast travel time. Different parameters for contrast injection were evaluated. Signal-to-noise ratio (SNR) measurements were performed and image quality and injection timing were evaluated. MRA was successful in all patients and image quality was considered very good in 52%. Adequate SNR was achieved with no significant differences between the MR sequences. SNR decreased only 25 - 30% between subsequent scans. The mean contrast dose was 0.23 mmol/kg. The mean scan time was 12.5±3.8 s; the shorter scan times made dynamic examinations possible with high temporal resolution. Highest spatial resolution was obtained with TR 4.6/5.0 sequences. A contrast dose of 0.2 mmol/kg b.w. is recommended with an injection rate of 0.5 to 1.2 ml/s, depending on patient size and scan time. The scan delay time should equal the contrast travel time for optimal vessel enhancement. In the future, contrast-enhanced MRA may be a potential alternative to angiocardiography in infants and children

  16. Chemical shift of Mn and Cr K-edges in X-ray absorption

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 36; Issue 6. Chemical shift of Mn and Cr K-edges in X-ray absorption spectroscopy with synchrotron radiation. D Joseph A K Yadav S N Jha D Bhattacharyya. Volume 36 Issue 6 November 2013 pp ...

  17. Investigation of Prussian Blue Analogs by XMCD at the K-edge of transition metals

    International Nuclear Information System (INIS)

    Bordage, A; Bleuzen, A; Nataf, L; Baudelet, F

    2016-01-01

    Despite transition metal (TM) K-edge x-ray magnetic circular dichroism (XMCD) seems an interesting tool to get magnetic and structural information at the atomic scale, the effects originating this signal are still poorly understood. We thus initiated a deep investigation of the TM K-edge XMCD using Prussian Blue analogs (PBA) as model-compounds. In a recent study of the NiFe PBA family, we demonstrated that the XMCD signals at the TM K-edges strongly vary with external (mechanical) or internal (chemical) pressure and so that they are highly sensitive to small structural distortions. Following these first results, we extended this approach to the MnFe and CoFe families to evaluate the effect of electronic parameters (number of unpaired electrons of the M II TM) on the XMCD signal. All the results set milestones in the disentanglement of the components originating the XMCD signals at the K-edge of TM and will eventually help in a better understanding of the photomagnetic properties of PBAs. (paper)

  18. The diagnostic value of three-dimensional dynamic contrast-enhanced MR angiography for intracranial aneurysms

    International Nuclear Information System (INIS)

    Liu Qi; Lu Jianping; Wang Fei; Wang Li; Tian Jianming; Jin Aiguo; Zeng Hao

    2003-01-01

    Objective: To assess the clinical value of three-dimensional dynamic contrast-enhanced MR angiography (3D DCE-MRA) in the detection for intracranial aneurysm. Methods: 3D DCE-MRA was performed in 54 patients highly suspected with intracranial aneurysms. Then conventional digital subtraction angiography (DSA) and feasible endovascular treatment were performed simultaneously. A three-dimensional fast imaging with steady state precession (3D FISP) was used for 3D DCE-MRA(Gd-DTPA dose, 0.2 mmol per kilogram for body weight; acquisition time, 10 seconds). The source images were subtracted from mask images and transferred to computer workstation. All images were subsequently post-processed using three-dimensional reconstruction. 3D DCE-MRA images and DSA images were compared for demonstration of the aneurysm, its neck, and relationship with parent artery, and the usefulness for endovascular treatment was evaluated. Results: There were 39 cases with 45 intracranial aneurysms. The sensitivity, specificity, and accuracy of 3D DCE-MRA were 96%, 73% and 90%, respectively. Aneurysm and its neck depiction at 3D DCE-MRA was significantly better than that at DSA, especially for aneurysms adjacent to the cavernous sinus and near the PICA of vertebral artery. 3D DEC-MRA could guide neurosurgeons to the desired DSA projection, and helped them make plan for interventional or surgical treatment in advance. But the diagnosis should be very carefully made for small aneurysms located in the periphery and the arterial bifurcation. Conclusion: 3D DEC-MRA is a fast, noninvasive and efficient technique for diagnosing intracranial aneurysms. Its three dimensional information is helpful for DSA demonstration and treatment planning. Any uncertain diagnosis requires DSA confirmation

  19. Evaluation of the vascular anatomy in potential living kidney donors with gadolinium-enhanced magnetic resonance angiography: comparison with digital subtraction angiography and intraoperative findings.

    Science.gov (United States)

    Asgari, Majid A; Dadkhah, Farid; Ghadian, Ali R; Razzaghi, Mohammad R; Noorbala, Mohammad H; Amini, Erfan

    2011-01-01

    X-ray contrast arteriography has traditionally been used for pre-operative evaluation in living kidney donors. However, magnetic resonance angiography (MRA) offers a non-invasive alternative, which has been considered to be less accurate. This study was performed to determine whether MRA in the pre-operative investigation of living kidney donors provides sufficient information. From December 2005 to December 2007, 173 potential live donors were evaluated in this study. Donors performed digital subtraction angiography (DSA) and those with one or more accessory arteries at least on one side recruited for further evaluation with three-dimensional gadolinium-enhanced MRA. A total of 30 donors constituted the study population. When compared with DSA as the reference method, MRA detected 20 of 36 renal accessory arteries which indicates a sensitivity of 55.6%. The difference between MRA and DSA in identifying accessory renal arteries was significant (p-value kidneys. MRA has the advantage of avoiding exposure to ionizing radiation and is non-invasive. These are important considerations in pre-operative evaluation of a generally healthy donor population. However, MRA provides suboptimal accuracy in detecting small accessory arteries. © 2010 John Wiley & Sons A/S.

  20. Supra-aortic low-dose contrast-enhanced time-resolved magnetic resonance (MR) angiography at 3 T: comparison with time-of-flight MR angiography and high-resolution contrast-enhanced MR angiography.

    Science.gov (United States)

    Lee, Youn-Joo; Kim, Bum-soo; Koo, Ja-Sung; Kim, Bom-Yi; Jang, Jinhee; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin

    2015-06-01

    Low-dose, time-resolved, contrast-enhanced, magnetic resonance angiography (TR-CEMRA) has been described previously; however, a comparative study between low dose TR-CEMRA and time-of-flight MRA (TOF-MRA) in the diagnosis of supra-aortic arterial stenosis has not yet been published. To demonstrate the feasibility and effectiveness of low-dose TR-CEMRA compared with TOF-MRA, using high-resolution contrast-enhanced MRA (HR-CEMRA) as the reference standard. This prospective study consisted of 30 consecutive patients. All patients underwent TOF-MRA of the neck and circle of Willis and supra-aortic HR-CEMRA, followed by supra-aortic low-dose TR-CEMRA. Gadoterate meglumine (Gd-DOTA, Dotarem(®), Guerbet, Roissy CdG Cedex, France) was injected at a dose of 0.1 mmol/kg for HR-CEMRA, followed by a 0.03 mmol/kg bolus for low-dose TR-CEMRA. Three readers evaluated the assessibility and image quality, and then two readers classified each stenosis into the following categories: normal (0-30%), mild stenosis (31-50%), moderate (51-70%), severe (71-99%), and occlusion. TR-CEMRA and HR-CEMRA showed a greater number of assessable arterial segments than TOF-MRA (P supra-aortic arterial stenosis, and could be more useful option than TOF-MRA. © The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  1. Evaluation of paraclinoid aneurysm by using contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Tsuboi, Toshiyuki; Takahashi, Kazuya; Date, Isao; Mandai, Shinya; Kinugasa, Kazushi; Nishimoto, Akira

    2004-01-01

    Juxta-dural ring aneurysms of the internal carotid artery have different clinical courses and risks of subarachnoid hemorrhage (SAH) depending upon their positions in the intradural or extradural spaces. The goal of this study was to localize such aneurysms using contrast enhanced-MR Angiography (CE-MRA). CE-MRA studies were performed in 18 patients with juxta-dural ring aneurysms using three-dimensional time-of-flight spoiled gradient-recalled acquisition in the steady state (3D-TOF-SPGR) sequence. Imaging parameters were as follows: 33/3.4/1 (repetition time/echo time/number of excitation (TR/TE/NEX)), flip angle 25 deg, 256 x 192 matrix, 0.8-mm slice thickness, 60 sections in total (one slab), 180-mm field of view, with no magnetization transfer contrast (MTC), superior saturation (S sat) pulse, total imaging time 6 minutes 53 seconds. We evaluated both the source images of CE-MRA and multiplanar reconstruction (MPR) images. When the hyperintensity of the aneurysm was located within the hyperintensity of the contrast-enhanced cavernous sinus, we diagnosed the lesion as an intracavernous, ''extradural'' aneurysm. In addition, we compared CE-MRA with operative findings. Seven patients out of 18 were treated surgically. In all, MRI findings corresponded well with the operative findings. We believe CE-MRA and its MPR images using 3D-TOF-SPGR sequence is a useful technique to evaluate juxta-dural ring aneurysms. (author)

  2. Gadofosveset trisodium-enhanced magnetic resonance angiography of the left atrium-A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Moritz, E-mail: moritz.wagner@charite.d [Department of Radiology, Charite - University Hospital, Berlin (Germany); Rief, Matthias; Asbach, Patrick [Department of Radiology, Charite - University Hospital, Berlin (Germany); Vogtmann, Thomas [Department of Cardioloy and Angiology, Charite - University Hospital, Berlin (Germany); Huppertz, Alexander [Imaging Science Institute Charite Berlin, Berlin (Germany); Beling, Mark [Department of Cardioloy and Angiology, Charite - University Hospital, Berlin (Germany); Butler, Craig [Mazankowski Alberta Heart Institute, University of Alberta, Edmonton (Canada); Laule, Michael [Department of Cardioloy and Angiology, Charite - University Hospital, Berlin (Germany); Warmuth, Carsten; Taupitz, Matthias; Hamm, Bernd; Lembcke, Alexander [Department of Radiology, Charite - University Hospital, Berlin (Germany)

    2010-08-15

    Aim: Imaging of the left atrium is regularly performed prior to pulmonary vein isolation. The aim of the study was to evaluate the feasibility of contrast-enhanced high-resolution magnetic resonance angiography (MRA) of the left atrium using the blood-pool contrast agent gadofosveset trisodium in comparison to noncontrast MRA. Materials and methods: Twenty consecutive patients were examined by free-breathing electrocardiogram-gated whole-heart MRA (reconstructed spatial resolution, 0.7 mm x 0.6 mm x 0.8 mm) with a noncontrast T2-prepared steady state free precession sequence (T2-prep SSFP) and a gadofosveset trisodium-enhanced inversion-recovery SSFP sequence (CE IR-SSFP). Contrast-to-noise ratio (CNR) of blood in the left atrium was determined. Depiction of the left atrium was rated by two radiologists in consensus. A cardiologist segmented the MR data sets and rated depiction of the left atrium. Results: Five of 20 patients had irregular breathing patterns with navigator efficiency less than 35% and were excluded from evaluation. CNR was significantly higher for CE IR-SSFP compared with T2-prep SSFP (18.4 {+-} 5.3 vs. 11.7 {+-} 3.5, p < 0.01). Depiction of the left atrium by T2-prep SSFP was rated as good in four patients, moderate in ten patients, and poor in one patient, whereas depiction of the left atrium by CE IR-SSFP was rated as excellent in nine patients, good in four patients, and moderate in two patients. CE IR-SSFP allowed for semiautomated segmentation of the left atrium in 15 patients, whereas T2-prep SSFP allowed for segmentation only in ten patients. Conclusion: Gadofosveset trisodium-enhanced MRA of the left atrium is feasible with significantly improved image quality compared to noncontrast MRA.

  3. Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption

    DEFF Research Database (Denmark)

    Wolf, T. J. A.; Myhre, Rolf H.; Cryan, J. P.

    2017-01-01

    -edge soft X-ray absorption spectroscopy. As a hole forms in the n orbital during ππ*/nπ* internal conversion, the absorption spectrum at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept using the nucleobase thymine at the oxygen K-edge, and unambiguously show that ππ...

  4. Visualization of pigment distributions in paintings using synchrotron K-edge imaging

    International Nuclear Information System (INIS)

    Krug, K.; Dik, J.; Leeuw, M.; Whitson, A. den; Tortora, J.; Coan, P.; Nemoz, C.; Bravin, A.

    2006-01-01

    X-ray radiography plays an important role in the study of artworks and archaeological artifacts. The internal structure of objects provides information on genesis, authenticity, painting technique, material condition and conservation history. Transmission radiography, however, does not provide information on the exact elemental composition of objects and heavy metal layers can shadow or obscure the ones including lighter elements. This paper presents the first application of synchrotron-based K-edge absorption imaging applied to paintings. Using highly monochromatic radiation, K-edge imaging is used to obtain elemental distribution images over large areas. Such elemental maps visualize the distribution of an individual pigment throughout the paint stratigraphy. This provides color information on hidden paint layers, which is of great relevance to art historians and painting conservators. The main advantage is the quick data acquisition time and the sensitivity to elements throughout the entire paint stratigraphy. The examination of a test painting is shown and further instrumental developments are discussed. (orig.)

  5. Iodine K-edge EXAFS analysis of iodide ion-cyclodextrin inclusion complexes in aqueous solution

    International Nuclear Information System (INIS)

    Kaneko, T; Ueda, M; Nagamatsu, S; Konishi, T; Fujikawa, T; Mizumaki, M

    2009-01-01

    We study the structure of inclusion complexes of α-, β-, γ-cyclodextrin with mono-iodide ion in aqueous solution by means of iodine K-edge EXAFS spectroscopy. The analysis is based on the assumption that two kinds of iodide ions exist in KI-cyclodextrin aqueous solution i.e. hydrated mono-iodide ions and one-one mono-iodide-cyclodextrin inclusion complexes. In KI-α-cyclodextrin system, iodine K-edge EXAFS analyse show that the average coordination number of the oxygen atoms in water molecules in the first hydration shell decreases as the fraction of included ions increases. This result suggests that dehydration process accompanies the formation of the inclusion complex. This is not found in the case of β-cyclodextrin, indicating that in this case the iodide ions are included together with the whole first hydration shell.

  6. Venous reflux on contrast-enhanced head and neck magnetic resonance angiography: Analysis of causative factors

    International Nuclear Information System (INIS)

    Shin, Dong Jae; Lee, Eun Ja; Bae, Jong Myon

    2016-01-01

    The purpose of this study was to analyze the causative factors of venous reflux on contrast-enhanced head and neck magnetic resonance angiography. We retrospectively reviewed 150 patients with right-arm injections and 150 patients with left-arm injections. We included the age, gender, body mass index, history of hypertension, and history of diabetes mellitus in the evaluation of all patients. We measured the shortest width of the left or right brachiocephalic vein (BCV), the diameter of the aortic arch, and the distance between the sternum and vertebral body. The relationship between these factors and the venous reflux was analyzed. In patients with venous reflux, we performed qualitative image scoring for suboptimal images. In patients with venous reflux, the image quality of the left-arm injection group was significantly inferior to the image quality of the right-arm injection group. The mean age and the male-to-female ratio of patients with venous reflux were significantly higher than those of patients without venous reflux. In patients receiving the left-arm injection, the mean shortest width of the left BCV was significantly narrower in patients with venous reflux than in patients without venous reflux. A left-arm injection should be avoided, especially in elderly patients, to acquire an optimal image

  7. Venous reflux on contrast-enhanced head and neck magnetic resonance angiography: Analysis of causative factors

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Dong Jae; Lee, Eun Ja [Dept. of Radiology, Dongguk University Ilsan Hospital, Goyang (Korea, Republic of); Bae, Jong Myon [Dept. of Preventive Medicine, Jeju National University School of Medicine, Jeju (Korea, Republic of)

    2016-12-15

    The purpose of this study was to analyze the causative factors of venous reflux on contrast-enhanced head and neck magnetic resonance angiography. We retrospectively reviewed 150 patients with right-arm injections and 150 patients with left-arm injections. We included the age, gender, body mass index, history of hypertension, and history of diabetes mellitus in the evaluation of all patients. We measured the shortest width of the left or right brachiocephalic vein (BCV), the diameter of the aortic arch, and the distance between the sternum and vertebral body. The relationship between these factors and the venous reflux was analyzed. In patients with venous reflux, we performed qualitative image scoring for suboptimal images. In patients with venous reflux, the image quality of the left-arm injection group was significantly inferior to the image quality of the right-arm injection group. The mean age and the male-to-female ratio of patients with venous reflux were significantly higher than those of patients without venous reflux. In patients receiving the left-arm injection, the mean shortest width of the left BCV was significantly narrower in patients with venous reflux than in patients without venous reflux. A left-arm injection should be avoided, especially in elderly patients, to acquire an optimal image.

  8. Advantages of time-resolved contrast-enhanced 4D MR angiography in splenic arterial steal syndrome.

    Science.gov (United States)

    Obmann, Verena C; Chalian, Majid; Mansoori, Bahar; Sanchez, Edmund; Gulani, Vikas

    2018-03-07

    Splenic artery steal syndrome (SASS) is a severe complication affecting up to 10% of orthotopic liver transplant (OLT) patients. In this case report, we present a 35-year-old male with OLT secondary to liver failure due to hemochromatosis, who developed SASS. We describe potential application of different imaging techniques for diagnosis of SASS with focus on the value of time-resolved contrast enhanced 4D magnetic resonance angiography (MRA). Copyright © 2018 Elsevier Inc. All rights reserved.

  9. The clinical value of three-dimensional contrast-enhanced MR angiography in abdominal aortic aneurysms

    International Nuclear Information System (INIS)

    Liu Qi; Lu Jianping; Tian Jianming; Wang Fei; Wang Li; Jin Aiguo; Zeng Hao; Gong Jianguo

    2004-01-01

    Objective: To evaluate the clinical value of three-dimensional contrast-enhanced MR angiography (3D CE-MRA) and its 3D reconstruction in the diagnosis of abdominal aortic aneurysms (AAA). Methods: Sixty-three patients with clinically diagnosed AAA underwent 3D CE-MRA combined with other sequences. 3D CE-MRA was performed with a 3D FISP sequence(TR, TE, FA=3.64 ms, 1.44 ms, 25 degrees, matrix=196 x 512, eff. slice=1.8 mm, FOV 30 cm x 40 cm, acquisition time=18-20 s) after injection of 0.2 mmol Gd-DTPA per kg b. w. A bolus-test was done before angiography to optimize imaging delay time. After 3D CE-MRA a T 1 -weighted sequence was acquired on the axial plane. The source images were subtracted from mask images and transferred to computer workstation, and subsequently post-processed using 3D reconstruction. All sequences were used to depict the type, location, extent, and thrombosis of the AAA, the morphology of its proximal neck, the distal aortoiliac inflow tract, and the relationship with the branches of aorta. The length, diameter, and angle of the aneurysm sac, and proximal and distal arteries were measured. The clinical role was evaluated for treatment planning. Results: High-quality 3D CE-MRA/MRI images were obtained in all patients. Among them, fifty-six had infrarenal AAA, five juxtarenal AAA, and two AAA with suprarenal extension. The mean diameter of aneurysms was 5.3 cm. The thrombosis was thicker than 2.0 cm in 26 patients. 3D CE-MRA clearly demonstrated the morphology and extent of AAA, and its proximal neck and distal aortoiliac inflow tract. The accurate parameters needed by endovascular treatment were gained simultaneously. Aneurysm and its neck depiction at 3D CE-MRA was better than that at DSA. The endovascular and surgical treatment were selected according the images (31 endovascular treatment, 4 surgical treatment, 28 conservative treatment only). The parameters at 3D CE-MRA coincided well with those at DSA in all cases (P>0.1). Conclusion: 3D CE

  10. Phosphorus Speciation of Forest-soil Organic Surface Layers using P K-edge XANES Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    J Prietzel; J Thieme; D Paterson

    2011-12-31

    The phosphorus (P) speciation of organic surface layers from two adjacent German forest soils with different degree of water-logging (Stagnosol, Rheic Histosol) was analyzed by P K-edge XANES and subsequent Linear Combination Fitting. In both soils, {approx}70% of the P was inorganic phosphate and {approx}30% organic phosphate; reduced P forms such as phosphonate were absent. The increased degree of water-logging in the Histosol compared to the Stagnosol did not affect P speciation.

  11. Value of Single-Dose Contrast-Enhanced Magnetic Resonance Angiography Versus Intraarterial Digital Subtraction Angiography in Therapy Indications in Abdominal and Iliac Arteries

    International Nuclear Information System (INIS)

    Schaefer, Philipp J.; Schaefer, Fritz K. W.; Mueller-Huelsbeck, Stefan; Both, Markus; Heller, Martin; Jahnke, Thomas

    2007-01-01

    The objective of the study was to prove the value of single-dose contrast-enhanced magnetic resonance angiography [three-dimensional (3D) ceMRA] in abdominal and iliac arteries versus the reference standard intra-arterial digital subtraction angiography (i.a.DSA) when indicating a therapy. Patients suspected of having abdominal or iliac artery stenosis were included in this study. A positive vote of the local Ethics Committee was given. After written informed consent was obtained, 37 patients were enrolled, of which 34 were available for image evaluation. Both 3D ceMRA and i.a. DSA were performed for each patient. The dosage for 3D ceMRA was 0.1 mmol/kg body weight in a 1.5-T scanner with a phased-array coil. The parameters of the 3D-FLASH sequence were as follows: TR/TE 4.6/1.8 ms, effective thickness 3.5 mm, matrix 512 x 200, flip angle 30 o , field of view 420 mm, TA 23 s, coronal scan orientation. Totally, 476 vessel segments were evaluated for stenosis degree by two radiologists in a consensus fashion in a blinded read. For each patient, a therapy was proposed, if clinically indicated. Sensitivity, specificity, positive and negative predictive values, and accuracy for stenoses ≥50% were 68%, 92%, 44%, 97%, and 90%, respectively. In 13/34 patients, a discrepancy was found concerning therapy decisions based on MRA findings versus therapy decisions based on the reference standard DSA. The results showed that the used MRA imaging technique of abdominal and iliac arteries is not competitive to i.a. DSA, with a high rate of misinterpretation of the MRAs resulting in incorrect therapies

  12. The evaluation of three-dimensional dynamic contrast enhanced MR angiography in portal hypertension

    International Nuclear Information System (INIS)

    Wu Zhuo; Liang Biling; Liu Qingyu; Zhong Jinglian; Ye Ruixin; Ling Yunbiao; Ou Qingjia

    2006-01-01

    Objective: To evaluate the techniques of three-dimensional dynamic contrast enhanced MR angiography (3D DCE MRA)with normative timing of sequences, enhancive 3D slab thickness and subtraction in portosystemic collaterals. Methods: Before April 2003, 12 patients were performed with 75-90 mm of 3D slab thickness and 3-5 repeated sequences estimated by breath, after April 2003, 18 patients were performed with 150-180 mm of 3D slab thickness and 5 normative repeated sequences respectively at 0, 20, 40, 60 and 90 s. After subtracting selective arterial phase images from subsequent portal venous phase images, two radiologists assessed visualization of portal collaterals independently with a four - point scale for ranking of image quality in maximum intensity projection (MIP) images with and without subtraction. Results: Average scores for image quality in visualization of the portal vein with subtraction were significantly depressed compared with the scores without subtraction (2.53±0.49 versus 2.74±0.31, P<0.05). However, subtraction three dimension-maximum intensity projection (3D-MIP) gave superior visualization of portal collaterals compared with non-subtraction 3D-MIP(2.58±0.30 versus 1.63±0.50). A statistically significant difference (P<0.01) was found between the two groups of esophageal varices. Most of portosystemic shunts demonstrated in the same time as the portal vein at about 20s, but some of collaterals demonstrated in delay time. Conclusion: Subtraction 3D-MIP demonstrates portosystemic collaterals more clearly than non-subtraction; normative timing of sequences ensure against omitting varices displayed late, 3 D slab thickness provides details about paraumbilical vein and retroperitoneal collaterals. (authors)

  13. Ultrafast contrast-enhanced 3D MR angiography of the aorta and renal arteries in apnoea

    International Nuclear Information System (INIS)

    Hany, T.F.; Pfammatter, T.; Schmidt, M.; Leung, D.A.; Debatin, J.F.

    1997-01-01

    Purpose: To determine the value of ultrafast, gadolinium-enhanced, three-dimensional breathhold magnetic resonance angiography (MRA) in the assessment of the aorta and renal arteries in comparison to conventional arteriography (CA). Patients and methods: 49 patients (31 m, 18 f) were evaluated with both CA and 3D MRA. The 3D MRA data set consisted of 44 continuous sections, acquired in apnoea (23-28 s) using the following parameters: T R /T E 3.9/1.5 ms, flip angle 40 , 3/4 k-space acquisition. 0.3 mmol/kg BW gadolinium-DTPA were administered intravenously in a bolus, using an automated injector. A test bolus method was used for timing of the bolus and beginning of the data acquisition. Intraarterial CA was used as the gold standard in 47 patients; in two patients the intraoperative findings were employed as the standard of reference. CA and MRA were interpreted separately by two different radiologists, who were blinded to the results of the other examine. Results: All 11 accessory renal arteries were visualised on MRA. MRA-based assessment of renal artery stenosis was identical with CA in 31 of 41 (75%) stenoses. Sensitivity and specificity values for assessment of renal arterial disease were 84,4% and 96,1%, for haemodynamically significant lesions they amounted to 90% and 98,9%, respectively. Conclusion: The presented ultrafast contrast-enhanced 3D MRA technique allows for the reliable assessment of aortic and renal arterial morphology and pathology. (orig.) [de

  14. Catheter Angiography

    Medline Plus

    Full Text Available ... is performed using: x-rays with catheters computed tomography (CT) magnetic resonance imaging (MRI) In catheter angiography, ... tumor; this is called superselective angiography. Unlike computed tomography (CT) or magnetic resonance (MR) angiography , use of ...

  15. Catheter Angiography

    Medline Plus

    Full Text Available ... is performed using: x-rays with catheters computed tomography (CT) magnetic resonance imaging (MRI) In catheter angiography, a ... tumor; this is called superselective angiography. Unlike computed tomography (CT) or magnetic resonance (MR) angiography , use of a ...

  16. Catheter Angiography

    Medline Plus

    Full Text Available ... using: x-rays with catheters computed tomography (CT) magnetic resonance imaging (MRI) In catheter angiography, a thin plastic ... called superselective angiography. Unlike computed tomography (CT) or magnetic resonance (MR) angiography , use of a catheter makes it ...

  17. Technique for arterial-phase contrast-enhanced three-dimensional MR angiography of the carotid and vertebral arteries.

    Science.gov (United States)

    Isoda, H; Takehara, Y; Isogai, S; Takeda, H; Kaneko, M; Nozaki, A; Sun, Y; Foo, T K

    1998-08-01

    Our goal was to evaluate whether contrast-enhanced three-dimensional MR angiography using the MR Smartprep technique would enable us to obtain arterial-phase MR angiograms of the carotid and vertebral arteries. The study included 35 patients with suspected lesions of the neck in whom the MR Smartprep technique was used for MR angiography performed with a 1.5-T superconducting system. The tracker volume was placed primarily in the middle part of the right common carotid artery. The imaging volume was placed in a coronal direction to include the carotid and vertebral arteries from the aortic arch to the skull base. A centric phase-ordering scheme was used. Imaging times were 20 to 38 seconds for 14 patients and 11 to 16 seconds for 21 patients. By using a smaller tracker volume and an imaging time of less than 16 seconds, we were able to achieve a 100% successful triggering rate and to delineate selectively arterial-phase carotid and vertebral arteries with almost no venous contamination. Contract-enhanced 3-D MR angiography with the MR Smartprep technique was useful for showing arterial-phase carotid and vertebral arteries selectively.

  18. Contrast-enhanced magnetic resonance angiography in carotid artery disease: does automated image registration improve image quality?

    International Nuclear Information System (INIS)

    Menke, Jan; Larsen, Joerg

    2009-01-01

    Contrast-enhanced magnetic resonance angiography (MRA) is a noninvasive imaging alternative to digital subtraction angiography (DSA) for patients with carotid artery disease. In DSA, image quality can be improved by shifting the mask image if the patient has moved during angiography. This study investigated whether such image registration may also help to improve the image quality of carotid MRA. Data from 370 carotid MRA examinations of patients likely to have carotid artery disease were prospectively collected. The standard nonregistered MRAs were compared to automatically linear, affine and warp registered MRA by using three image quality parameters: the vessel detection probability (VDP) in maximum intensity projection (MIP) images, contrast-to-noise ratio (CNR) in MIP images, and contrast-to-noise ratio in three-dimensional image volumes. A body shift of less than 1 mm occurred in 96.2% of cases. Analysis of variance revealed no significant influence of image registration and body shift on image quality (p > 0.05). In conclusion, standard contrast-enhanced carotid MRA usually requires no image registration to improve image quality and is generally robust against any naturally occurring body shift. (orig.)

  19. Comparison of contrast-enhanced magnetic resonance angiography and conventional pulmonary angiography for the diagnosis of pulmonary embolism : a prospective study

    NARCIS (Netherlands)

    Oudkerk, M; van Beek, EJR; Wielopolski, P; van Ooijen, PMA; Brouwers-Kuyper, EMJ; Bongaerts, AHH; Berghout, A

    2002-01-01

    Background Diagnostic strategies for pulmonary embolism are complex and consist of non-invasive diagnostic tests done to avoid conventional pulmonary angiography as much as possible. We aimed to assess the diagnostic accuracy of magnetic resonance angiography (MRA) for the diagnosis of pulmonary

  20. Preoperative evaluation of neurovascular relationship by using contrast-enhanced and unenhanced 3D time-of-flight MR angiography in patients with trigeminal neuralgia

    International Nuclear Information System (INIS)

    Qin, Zhou; Zhiling, Liu; Chuanfu, Li; Qingshi Zeng; Chuncheng, Qu; Shilei, Ni

    2011-01-01

    Background Microvascular decompression is an etiological strategy for the therapy of trigeminal neuralgia (TN). Preoperative identification of neurovascular compression, therefore, could have an impact on the determination of appropriate treatment for TN. Purpose To evaluate the value of contrast-enhanced and unenhanced three-dimensional (3D) time-of-flight (TOF) MR angiography in the visualization of neurovascular relationship in patients with TN. Material and Methods Thirty-seven patients with unilateral TN underwent unenhanced and contrast-enhanced 3D TOF MR angiography with a 3.0-T MR system. Images were reviewed by a radiologist blinded to clinical details. Vascular contact with the trigeminal nerve was identified, and the nature of the involved vessels (artery or vein) was determined. All patients underwent microvascular decompression. Results In 37 patients with TN, contrast-enhanced 3D TOF MR angiography identified surgically verified neurovascular contact in 35 of 36 symptomatic nerves, and there was no false-positive. Based on surgical findings, the sensitivity of MR imaging was 97.2% and specificity 100%. The nature of the offending vessel was correctly identified in 94.4% of the patients by using the combination of contrast-enhanced and unenhanced MR angiography. Conclusion Contrast-enhanced 3D TOF MR angiography is useful in the detection of vascular contact with the trigeminal nerve in patients with TN, and this MR imaging in combination with unenhanced MR angiography could help in the identification of the nature of the responsible vessels

  1. Evaluation of renal vascular in living donors before transplantation using dynamic contrast enhanced MR angiography

    International Nuclear Information System (INIS)

    Wang Hong; Mu Xuetao; Zhong Xin; Dong Yuru; Dong Yue; Ma Yi; Wu Chunnan

    2010-01-01

    Objective: To explore whether dynamic contrast-enhanced MRA (DCE MRA) can provide an effective assessment of renal vascular in living donors before transplantation. Methods: Thirty five healthy living renal donor candidates were scanned on MR system before transplantation. After injection of Gd-DTPA 1 ml in vein, a test-bolus scan was used to get the time delay of Gd-DTPA reaching renal artery. Then, a 3D T 1 -weighted fast low-angle shot sequence (3D FLASH) was performed in the coronal plane. The 3D FLASH scan would repeat four times with an inter-phase of 10 seconds. Thus, the imaging of the renal arterial, venous and collecting systems were got. Two radiologists observed renal arteries and veins on original imaging and MIP reconstmcted imaging. The quality of MR angiography was evaluated on a five- point scale and the vascular anatomy or variations of the arterial and venous systems were recorded, using intraoperative findings as a standard of reference. Results: The quality for all MRA was good or very good for the most of living renal donors. Among 70 renals, several variations of vascular were found, including 5 left accessory artery, 9 right accessory artery, 3 left proximal arterial branch and 6 right proximal arterial branch. Among 70 renal veins, 1 right accessory veins and 2 left varicocele were observed. One small accessory artery of right kidney was missed with DCE MRA, but identified by operation. Conclusion: DCE MRA was noninvasive tool for evaluation of the renal vasculature and variations with high accuracy. It would be a good modality in preoperative evaluation of living renal donors. (authors)

  2. Gas enhanced magnetic resonance angiography of the cerebrum using carbon dioxide and oxygen - preliminary results

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Hansen, Kristoffer Lindskov; Ohlhues, Anders

    Purpose/introduction Standard imaging of the cerebral arteries is performed using intravenous contrast in CT angiography and x-ray angiography. Magnetic resonance angiography (MRA) of the cerebral arteries using intravenous contrast media does not perform well. Contrast in the venous bed...... and Methods Two healthy volunteers were scanned during inhalation of three different gas mixtures: Gas I (air), Gas II (5% CO2, 21 % O2, 74 % N2), Gas III (5% CO2, 95% O2). For each gas mixture a time of flight (TOF) series on the cerebral arteries was performed. Following each TOF series an ECG-gated phase...... contrast sequence was performed to calculate volume flow in the common carotid arteries. MRA data was acquired with a 1.5 T Siemens VISION MR-system (SIEMENS Medical Systems, Germany) using a standard circularly polarized head coil. Reconstructed images of TOF series and volume flow measurements were...

  3. Actinide L-line ED-XRF and Hybrid K-edge Densitometer Spectra Processing

    International Nuclear Information System (INIS)

    Esbelin, E.

    2015-01-01

    The analysis laboratory in the CEA Atalante complex at Marcoule (France) performs numerous R and D studies carried out in glove-boxes or in hot cells. Most of the samples are measured in liquid phase, aqueous or organic. The concentration of the main actinides of interest (U, Np, Pu, Am and Cm) are determined by XRF in a hot cell via their L-line X-ray between 13 and 15 keV. In order to limit the counting rate of many radioactive emitters (X-ray and gamma emitters) in the analysis solution and the continuous spectrum, a graphite monochromator is placed between the sample and detector. Commercial or free, the software packages available for processing X-ray spectra are designed and dedicated to a specific instrument and/or do not take into account the specific feature of our system, in other words, the presence of a monochromator. Therefore, a new X-ray analysis software programme was developed for this particular system which takes into account matrix effects corrections. For sample with U and/or Pu in high concentrations, the hybrid K-edge densitometer is used. A new software programme was also developed. For K-edge densitometry spectra processing, no calibration process is used. Spectra processing is based on theoretical equation and uses XCOM database for mass attenuation coefficients. Measured spectra on K-edge densitometer of Rokkasho Safeguards Analytical Laboratory were processed with this software and a very good agreement was found with IDTIMS results. The new graphical user interface allows to manually correct the defined edge. For the XRF spectra processing, new algorithms are used to define the base line and to find/integrate peaks. With these two analytical devices in laboratory, U and Pu concentrations can be measured from 0.5 mg/l to several hundred of g/l. (author)

  4. Spectral K-edge subtraction imaging of experimental non-radioactive barium uptake in bone.

    Science.gov (United States)

    Panahifar, Arash; Samadi, Nazanin; Swanston, Treena M; Chapman, L Dean; Cooper, David M L

    2016-12-01

    To evaluate the feasibility of using non-radioactive barium as a bone tracer for detection with synchrotron spectral K-edge subtraction (SKES) technique. Male rats of 1-month old (i.e., developing skeleton) and 8-month old (i.e., skeletally mature) were orally dosed with low dose of barium chloride (33mg/kg/day Ba 2+ ) for 4weeks. The fore and hind limbs were dissected for imaging in projection and computed tomography modes at 100μm and 52μm pixel sizes. The SKES method utilizes a single bent Laue monochromator to prepare a 550eV energy spectrum to encompass the K-edge of barium (37.441keV), for collecting both 'above' and 'below' the K-edge data sets in a single scan. The SKES has a very good focal size, thus limits the 'crossover' and motion artifacts. In juvenile rats, barium was mostly incorporated in the areas of high bone turnover such as at the growth plate and the trabecular surfaces, but also in the cortical bone as the animals were growing at the time of tracer administration. However, the adults incorporated approximately half the concentration and mainly in the areas where bone remodeling was predominant and occasionally in the periosteal and endosteal layers of the diaphyseal cortical bone. The presented methodology is simple to implement and provides both structural and functional information, after labeling with barium, on bone micro-architecture and thus has great potential for in vivo imaging of pre-clinical animal models of musculoskeletal diseases to better understand their mechanisms and to evaluate the efficacy of pharmaceuticals. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  5. XANES at the silicon k-edge in the kaolin-meta kaolin-geopolymer system

    International Nuclear Information System (INIS)

    Lima, F.T.; Silva, F.J.; Thaumaturgo, C.

    2005-01-01

    The geo polymer synthesis process optimization pretends to control the re logical and mechanical properties. The Al/Si ratio is the main variable that governs the geo polymerization process. This control occurs by changing temperature, pressure and chemical composition of the geo polymer. Thermal analysis (DTA/DSC), microscopic (SEM/TEM) and spectroscopic (FTIR, XRD, SAXS, EXAFS and XANES) techniques have been used to characterize these inorganic systems. In this work, XANES spectra of the k-edge silicon (Si) of the kaolin-meta kaolin-geo polymer are presented. The XANES spectra provides the oxidation state and structural information about the present studied atom: Silicon (Si). (author)

  6. The hybrid K-edge/K-XRF densitometer: Principles - design - performance

    International Nuclear Information System (INIS)

    Ottmar, H.; Eberle, H.

    1991-02-01

    The Euratom Safeguards Directorate (ESD) has recently installed a hybrid K-edge/K-XRF densitometer in a commerical reprocessing plant for the safeguarding of nuclear materials. This instrument, developed at KfK Karlsruhe, offers for the first time analytical measurement capabilities for timely on-site input accountancy verification. Lectures providing informations on measurement principles, instrument design features and performance data have been given to inspectors of ESD to make them familiar with the new instrument. This report summarizes the essential materials presented during these courses. (orig.) [de

  7. Sensitivity of photon-counting based K-edge imaging in X-ray computed tomography.

    Science.gov (United States)

    Roessl, Ewald; Brendel, Bernhard; Engel, Klaus-Jürgen; Schlomka, Jens-Peter; Thran, Axel; Proksa, Roland

    2011-09-01

    The feasibility of K-edge imaging using energy-resolved, photon-counting transmission measurements in X-ray computed tomography (CT) has been demonstrated by simulations and experiments. The method is based on probing the discontinuities of the attenuation coefficient of heavy elements above and below the K-edge energy by using energy-sensitive, photon counting X-ray detectors. In this paper, we investigate the dependence of the sensitivity of K-edge imaging on the atomic number Z of the contrast material, on the object diameter D , on the spectral response of the X-ray detector and on the X-ray tube voltage. We assume a photon-counting detector equipped with six adjustable energy thresholds. Physical effects leading to a degradation of the energy resolution of the detector are taken into account using the concept of a spectral response function R(E,U) for which we assume four different models. As a validation of our analytical considerations and in order to investigate the influence of elliptically shaped phantoms, we provide CT simulations of an anthropomorphic Forbild-Abdomen phantom containing a gold-contrast agent. The dependence on the values of the energy thresholds is taken into account by optimizing the achievable signal-to-noise ratios (SNR) with respect to the threshold values. We find that for a given X-ray spectrum and object size the SNR in the heavy element's basis material image peaks for a certain atomic number Z. The dependence of the SNR in the high- Z basis-material image on the object diameter is the natural, exponential decrease with particularly deteriorating effects in the case where the attenuation from the object itself causes a total signal loss below the K-edge. The influence of the energy-response of the detector is very important. We observed that the optimal SNR values obtained with an ideal detector and with a CdTe pixel detector whose response, showing significant tailing, has been determined at a synchrotron differ by factors of

  8. K-edge energy-based calibration method for photon counting detectors

    Science.gov (United States)

    Ge, Yongshuai; Ji, Xu; Zhang, Ran; Li, Ke; Chen, Guang-Hong

    2018-01-01

    In recent years, potential applications of energy-resolved photon counting detectors (PCDs) in the x-ray medical imaging field have been actively investigated. Unlike conventional x-ray energy integration detectors, PCDs count the number of incident x-ray photons within certain energy windows. For PCDs, the interactions between x-ray photons and photoconductor generate electronic voltage pulse signals. The pulse height of each signal is proportional to the energy of the incident photons. By comparing the pulse height with the preset energy threshold values, x-ray photons with specific energies are recorded and sorted into different energy bins. To quantitatively understand the meaning of the energy threshold values, and thus to assign an absolute energy value to each energy bin, energy calibration is needed to establish the quantitative relationship between the threshold values and the corresponding effective photon energies. In practice, the energy calibration is not always easy, due to the lack of well-calibrated energy references for the working energy range of the PCDs. In this paper, a new method was developed to use the precise knowledge of the characteristic K-edge energy of materials to perform energy calibration. The proposed method was demonstrated using experimental data acquired from three K-edge materials (viz., iodine, gadolinium, and gold) on two different PCDs (Hydra and Flite, XCounter, Sweden). Finally, the proposed energy calibration method was further validated using a radioactive isotope (Am-241) with a known decay energy spectrum.

  9. The accuracy and utility of contrast-enhanced MR angiography for localization of spinal dural arteriovenous fistulas: the Toronto experience

    Energy Technology Data Exchange (ETDEWEB)

    Lindenholz, Arjen [University Medical Center Groningen, Department of Neurosurgery AB71, PO Box 30001, Groningen (Netherlands); Toronto Western Hospital, Department of Medical Imaging, Division of Neuroradiology, Toronto, ON (Canada); TerBrugge, Karel G.; Farb, Richard I. [Toronto Western Hospital, Department of Medical Imaging, Division of Neuroradiology, Toronto, ON (Canada); Dijk, J.M.C. van [University Medical Center Groningen, Department of Neurosurgery AB71, PO Box 30001, Groningen (Netherlands)

    2014-11-15

    The purpose of this study was to determine the accuracy and utility of contrast-enhanced MR angiography (CE-MRA) in spinal dural arteriovenous fistulas (SDAVF). A retrospective analysis from 1999-2012 identified 70 patients clinically suspected of harboring a SDAVF. Each patient underwent consecutive conventional MR-imaging, CE-MRA, and digital subtraction angiography (DSA). The presence or absence of serpentine flow voids, T2-weighted hyperintensity, and cord enhancement were evaluated, as well as location of the fistula as predicted by CE-MRA. DSA was used as the reference standard. Of the 70 cases, 53 were determined to be a SDAVF, 10 cases were shown to be other forms of vascular malformation, and 7 were DSA-negative. On MRI, all reported cases of SDAVF showed serpentine flow voids (100 %). T2-weighted hyperintensity was seen in 48 of 50 cases (96 %), extending to the conus in 41 of 48 cases (85 %). Cord enhancement was seen in 38 of 41 cases (93 %). CE-MRA correctly localized the SDAVF in 43 of the 53 cases (81 %). CE-MRA is a useful non-invasive examination for the detection and localization of SDAVF. CE-MRA facilitates but does not replace DSA as confirmation of location, fistula type, and arterial detail, which are required before treatment. (orig.)

  10. Gadofosveset-enhanced MR angiography of the pedal arteries in patients with diabetes mellitus and comparison with selective intraarterial DSA

    International Nuclear Information System (INIS)

    Roehrl, Boris; Kunz, Rainer Peter; Oberholzer, Katja; Pitton, Michael Bernhard; Dueber, Christoph; Kreitner, Karl-Friedrich; Neufang, Achim

    2009-01-01

    To compare gadofosveset-enhanced magnetic resonance angiography (MRA) of the pedal vasculature with selective intraarterial DSA. Eighteen patients with PAOD and type II diabetes were prospectively examined at 1.5 T. For contrast enhancement, 0.03 mmol/kg body weight gadofosveset was used. MR imaging consisted of dynamic and of high-resolution steady-state imaging. Selective digital subtraction angiography (DSA) was performed within 5 days and served as standard of reference. Image analysis was done by two observers. There were no differences between MRA and DSA regarding overall image quality. First-pass MRA detected significantly more patent vessel segments than did DSA (P < 0.001, kappa = 0.46). Interobserver agreement of MRA was very good with respect to the detection of patent vessel segments and the assessment of hemodynamically relevant stenoses (kappa = 0.97 and 0.89, respectively). Steady-state imaging depicted significantly more patent metatarsal arteries than did dynamic imaging, and delineated inflammatory complications including osteomyelitis, soft-tissue abscesses, and fistulas related to the diabetic foot. Gadofosveset-enhanced MRA of the pedal vasculature proved to be superior to DSA. It offered a long imaging time window, and allowed for better depiction of the pedal outflow. Steady-state imaging delineated inflammatory complications associated with the diabetic foot. (orig.)

  11. Gadofosveset-enhanced MR angiography of the pedal arteries in patients with diabetes mellitus and comparison with selective intraarterial DSA

    Energy Technology Data Exchange (ETDEWEB)

    Roehrl, Boris; Kunz, Rainer Peter; Oberholzer, Katja; Pitton, Michael Bernhard; Dueber, Christoph; Kreitner, Karl-Friedrich [Johannes Gutenberg University Mainz, Department of Diagnostic and Interventional Radiology, Mainz (Germany); Neufang, Achim [Johannes Gutenberg University Mainz, Department of Cardiothoracic and Vascular Surgery, Mainz (Germany)

    2009-12-15

    To compare gadofosveset-enhanced magnetic resonance angiography (MRA) of the pedal vasculature with selective intraarterial DSA. Eighteen patients with PAOD and type II diabetes were prospectively examined at 1.5 T. For contrast enhancement, 0.03 mmol/kg body weight gadofosveset was used. MR imaging consisted of dynamic and of high-resolution steady-state imaging. Selective digital subtraction angiography (DSA) was performed within 5 days and served as standard of reference. Image analysis was done by two observers. There were no differences between MRA and DSA regarding overall image quality. First-pass MRA detected significantly more patent vessel segments than did DSA (P < 0.001, kappa = 0.46). Interobserver agreement of MRA was very good with respect to the detection of patent vessel segments and the assessment of hemodynamically relevant stenoses (kappa = 0.97 and 0.89, respectively). Steady-state imaging depicted significantly more patent metatarsal arteries than did dynamic imaging, and delineated inflammatory complications including osteomyelitis, soft-tissue abscesses, and fistulas related to the diabetic foot. Gadofosveset-enhanced MRA of the pedal vasculature proved to be superior to DSA. It offered a long imaging time window, and allowed for better depiction of the pedal outflow. Steady-state imaging delineated inflammatory complications associated with the diabetic foot. (orig.)

  12. Budd-Chiari syndrome: dynamic enhancement findings with multi-slice helical CT and CT angiography analysis

    International Nuclear Information System (INIS)

    Meng Xiaochun; Shan Hong; Zhu Kangshun; Xu Chuan; Zhang Jiansheng; Liu Lingyun; Ye Binbin

    2005-01-01

    Objective: To investigate the dynamic enhancement regulations of liver and their mechanism in Budd-Chiari syndrome (BCS) by using multi-slice CT and evaluate the value of CT angiography in the diagnosis of BCS. Methods: 28 cases with BCS confirmed by digital subtraction angiography (DSA) were retrospectively analyzed. All patients underwent dynamic enhancement examinations with multi-slice CT within 1 week before DSA. The relevant vessels were reconstructed respectively with MIP, VR and MPR. Compared with the results of DSA, we analyzed the dynamic enhancement regulations of liver in BCS, estimated the value of dynamic enhancement CT exams and CTA techniques in judging the obstruction level and showing collateral vessels. Results: Of all 28 cases, CT correctly showed the obstruction level in 26 cases, and 2 had incorrect results which proved to be membranous obstruction of the inferior vena cava superior to diaphragm. In 22 cases with hepatic vein obstructions, hepatic parenchyma displayed typical patchy enhancement in 19, atypical patchy enhancement in 3.8 cases among these showed benign nodules. Simultaneously, CT showed stenosis and rigidity of portal vein branches in 20, enlargement of hepatic artery in 14, hepatic collateral vessels in 20 out of 22 cases. In 6 cases with simple obstruction of inferior vena cava, hepatic changes were not found. Collateral circulations in or out of liver corresponded to the obstruction level. Conclusion: Dynamic enhancement examinations with multi-slice CT can correctly reflect the hepatic hemodynamic changes. Transverse images, combined with CTA, can explicitly display the obstruction level of vascular lesions and collateral circulations in BCS. (authors)

  13. Noncontrast-enhanced magnetic resonance renal angiography using a repetitive artery and venous labelling technique at 3 T: comparison with contrast-enhanced magnetic resonance angiography in subjects with normal renal function

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Yoon [Sungkyunkwan University School of Medicine, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Seoul (Korea, Republic of); Severance Hospital, Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, Seoul (Korea, Republic of); Kim, Chan Kyo; Park, Byung Kwan [Sungkyunkwan University School of Medicine, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Seoul (Korea, Republic of); Kim, EunJu [Philips Healthcare Korea, Seoul (Korea, Republic of)

    2014-09-13

    To investigate the feasibility of noncontrast-enhanced MR angiography (NC-MRA) using the repetitive artery and venous labelling (RAVEL) technique to evaluate renal arteries compared to contrast-enhanced MR angiography (CE-MRA). Twenty-five subjects with normal renal function underwent NC-MRA using a RAVEL technique and CE-MRA at 3 T. Two independent readers analysed the MRA images. Image quality, number of renal arteries, presence or absence of an early branching vessel, and diameter of the main renal arteries were evaluated. The overall image quality of NC-MRA was fair or greater in 88 % of right and 92 % of left renal arteries, while it was 96 % in both sides with CE-MRA. On NC-MRA, the number of renal arteries in all subjects was perfectly predicted by both readers. Sensitivity and specificity for predicting early branching vessels were 82 % and 100 % for reader 1 and 82 % and 95 % for reader 2. Inter-modality agreement for comparing the diameters of main renal arteries was good or excellent at all segments for both readers. Inter-reader agreement was moderate or good at all segments except at the right distal segment on NC-MRA. NC-MRA with the RAVEL technique at 3 T may have comparable diagnostic feasibility for evaluating renal arteries compared to CE-MRA. (orig.)

  14. Usefulness of three-dimensional contrast-enhanced MR angiography in the evaluation of pelvic and lower extremity arteries

    International Nuclear Information System (INIS)

    Kim, Young Kon; Han, Young Min; Lee, Jeong Min

    2002-01-01

    To evaluate the feasibility and clinical usefulness of three-dimensional contrast-enhanced MR angiography (3D-CE-MRA) as a screening test in the evaluation of pelvic and lower extremity arterial diseases. Forty-four patients who underwent 3D-CE-MRA were included in this study. Coronal 3-dimensional gradient-echo, pre-and post contrast image were acquired with a dedicated peripheral vascular coil and moving-bed technique on a 1.5T MR system. Timing of start of data acquisition was determined by MR fluoroscopy technique, and 0.2 mmol/kg Gd-DTPA was injected into an antecubital vein, at a rate of 1cc/sec with an autoinjector. For quantitative analysis, signal to noise ratio (SNR) and artery to soft tissue contrast to noise ratio (CNR) of lower extremities arterial system including lower abdominal aorta were calculated. For qualitative analysis, arterial systems were divided into six segments, and were evaluated in terms of conspicuity of arterial systems and the degree of venous enhancement by three- and four-point scale respectively. In eight patients who underwent both MR angiography and conventional angiography as standard reference. Imaging analysis was done by means of consensus between two experienced radiologists. The mean time for the examination was about 15 min (± 5 min). The mean SNR of arterial system was 26.5±11.6, and mean artery to soft tissue contrast to noise ratio (CNR) was 24.6±11.2. Among the total 525 arterial segments 498 arterial segments (94.5%) could be demonstrated with good delineation of entire arterial tree. Good arterial imaging without or with minimal venous enhancement were demonstrated in 98.5% (260/264) in above knee and 89% (211/261) in below knee (p<0.01). Ten of 525 segments (1.9%) demonstrated severe venous overlapping and it mostly occurred in the calf region. In comparison with DSA, the sensitivity and the specificity for MR angiography for the detection of occlusions were 96% and 98.8%, respectively, and for the detection of

  15. Image quality and diagnostic accuracy of unenhanced SSFP MR angiography compared with conventional contrast-enhanced MR angiography for the assessment of thoracic aortic diseases

    Energy Technology Data Exchange (ETDEWEB)

    Krishnam, Mayil S. [University of California, Cardiovascular and Thoracic Imaging, UCI Medical Center, Irvine, CA (United States); Tomasian, Anderanik; Malik, Sachin; Ruehm, Stefan G. [University of California at Los Angeles, Department of Radiological Sciences, Ronald Reagan Medical Center, Los Angeles, CA (United States); Desphande, Vibhas; Laub, Gerhard [Siemens Medical Solutions, Los Angeles, CA (United States)

    2010-06-15

    The purpose of this study was to determine the image quality and diagnostic accuracy of three-dimensional (3D) unenhanced steady state free precession (SSFP) magnetic resonance angiography (MRA) for the evaluation of thoracic aortic diseases. Fifty consecutive patients with known or suspected thoracic aortic disease underwent free-breathing ECG-gated unenhanced SSFP MRA with non-selective radiofrequency excitation and contrast-enhanced (CE) MRA of the thorax at 1.5 T. Two readers independently evaluated the two datasets for image quality in the aortic root, ascending aorta, aortic arch, descending aorta, and origins of supra-aortic arteries, and for abnormal findings. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were determined for both datasets. Sensitivity, specificity, and diagnostic accuracy of unenhanced SSFP MRA for the diagnosis of aortic abnormalities were determined. Abnormal aortic findings, including aneurysm (n = 47), coarctation (n = 14), dissection (n = 12), aortic graft (n = 6), intramural hematoma (n = 11), mural thrombus in the aortic arch (n = 1), and penetrating aortic ulcer (n = 9), were confidently detected on both datasets. Sensitivity, specificity, and diagnostic accuracy of SSFP MRA for the detection of aortic disease were 100% with CE-MRA serving as a reference standard. Image quality of the aortic root was significantly higher on SSFP MRA (P < 0.001) with no significant difference for other aortic segments (P > 0.05). SNR and CNR values were higher for all segments on SSFP MRA (P < 0.01). Our results suggest that free-breathing navigator-gated 3D SSFP MRA with non-selective radiofrequency excitation is a promising technique that provides high image quality and diagnostic accuracy for the assessment of thoracic aortic disease without the need for intravenous contrast material. (orig.)

  16. Image quality and diagnostic accuracy of unenhanced SSFP MR angiography compared with conventional contrast-enhanced MR angiography for the assessment of thoracic aortic diseases

    International Nuclear Information System (INIS)

    Krishnam, Mayil S.; Tomasian, Anderanik; Malik, Sachin; Ruehm, Stefan G.; Desphande, Vibhas; Laub, Gerhard

    2010-01-01

    The purpose of this study was to determine the image quality and diagnostic accuracy of three-dimensional (3D) unenhanced steady state free precession (SSFP) magnetic resonance angiography (MRA) for the evaluation of thoracic aortic diseases. Fifty consecutive patients with known or suspected thoracic aortic disease underwent free-breathing ECG-gated unenhanced SSFP MRA with non-selective radiofrequency excitation and contrast-enhanced (CE) MRA of the thorax at 1.5 T. Two readers independently evaluated the two datasets for image quality in the aortic root, ascending aorta, aortic arch, descending aorta, and origins of supra-aortic arteries, and for abnormal findings. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were determined for both datasets. Sensitivity, specificity, and diagnostic accuracy of unenhanced SSFP MRA for the diagnosis of aortic abnormalities were determined. Abnormal aortic findings, including aneurysm (n = 47), coarctation (n = 14), dissection (n = 12), aortic graft (n = 6), intramural hematoma (n = 11), mural thrombus in the aortic arch (n = 1), and penetrating aortic ulcer (n = 9), were confidently detected on both datasets. Sensitivity, specificity, and diagnostic accuracy of SSFP MRA for the detection of aortic disease were 100% with CE-MRA serving as a reference standard. Image quality of the aortic root was significantly higher on SSFP MRA (P 0.05). SNR and CNR values were higher for all segments on SSFP MRA (P < 0.01). Our results suggest that free-breathing navigator-gated 3D SSFP MRA with non-selective radiofrequency excitation is a promising technique that provides high image quality and diagnostic accuracy for the assessment of thoracic aortic disease without the need for intravenous contrast material. (orig.)

  17. Solid energy calibration standards for P K-edge XANES: electronic structure analysis of PPh4Br.

    Science.gov (United States)

    Blake, Anastasia V; Wei, Haochuan; Donahue, Courtney M; Lee, Kyounghoon; Keith, Jason M; Daly, Scott R

    2018-03-01

    P K-edge X-ray absorption near-edge structure (XANES) spectroscopy is a powerful method for analyzing the electronic structure of organic and inorganic phosphorus compounds. Like all XANES experiments, P K-edge XANES requires well defined and readily accessible calibration standards for energy referencing so that spectra collected at different beamlines or under different conditions can be compared. This is especially true for ligand K-edge X-ray absorption spectroscopy, which has well established energy calibration standards for Cl (Cs 2 CuCl 4 ) and S (Na 2 S 2 O 3 ·5H 2 O), but not neighboring P. This paper presents a review of common P K-edge XANES energy calibration standards and analysis of PPh 4 Br as a potential alternative. The P K-edge XANES region of commercially available PPh 4 Br revealed a single, highly resolved pre-edge feature with a maximum at 2146.96 eV. PPh 4 Br also showed no evidence of photodecomposition when repeatedly scanned over the course of several days. In contrast, we found that PPh 3 rapidly decomposes under identical conditions. Density functional theory calculations performed on PPh 3 and PPh 4 + revealed large differences in the molecular orbital energies that were ascribed to differences in the phosphorus oxidation state (III versus V) and molecular charge (neutral versus +1). Time-dependent density functional theory calculations corroborated the experimental data and allowed the spectral features to be assigned. The first pre-edge feature in the P K-edge XANES spectrum of PPh 4 Br was assigned to P 1s → P-C π* transitions, whereas those at higher energy were P 1s → P-C σ*. Overall, the analysis suggests that PPh 4 Br is an excellent alternative to other solid energy calibration standards commonly used in P K-edge XANES experiments.

  18. K-edge x-ray-absorption spectroscopy of laser-generated Kr+ and Kr2+

    International Nuclear Information System (INIS)

    Southworth, S. H.; Arms, D. A.; Dufresne, E. M.; Dunford, R. W.; Ederer, D. L.; Hoehr, C.; Kanter, E. P.; Kraessig, B.; Landahl, E. C.; Peterson, E. R.; Rudati, J.; Santra, R.; Walko, D. A.; Young, L.

    2007-01-01

    Tunable, polarized, microfocused x-ray pulses were used to record x-ray absorption spectra across the K edges of Kr + and Kr 2+ produced by laser ionization of Kr. Prominent 1s→4p and 5p excitations are observed below the 1s ionization thresholds in accord with calculated transition energies and probabilities. Due to alignment of 4p hole states in the laser-ionization process, the Kr + 1s→4p cross section varies with respect to the angle between the laser and x-ray polarization vectors. This effect is used to determine the Kr + 4p 3/2 and 4p 1/2 quantum state populations, and these are compared with results of an adiabatic strong-field ionization theory that includes spin-orbit coupling

  19. Using X-ray, K-edge densitometry in spent fuel characterization

    International Nuclear Information System (INIS)

    Jensen, T.; Aljundi, T.; Gray, J.N.

    1998-01-01

    There are instances where records for spent nuclear fuel are incomplete, as well as cases where fuel assemblies have deteriorated during storage. To bring these materials into compliance for long term storage will require determination of parameters such as enrichment, total fissionable material, and burnup. To obtain accurate estimates of these parameters will require the combination of information from different inspection techniques. A method which can provide an accurate measure of the total uranium in the spent fuel is X-ray K-edge densitometry. To assess the potential for applying this method in spent fuel characterization, the authors have measured the amount of uranium in stacks of reactor fuel plates containing nuclear materials of different enrichments and alloys. They have obtained good agreement with expected uranium concentrations ranging from 60 mg/cm 2 to 3,000 mg/cm 2 , and have demonstrated that these measurements can be made in a high radiation field (> 200 mR/hr)

  20. Extended software for the KfK K-edge densitometer

    International Nuclear Information System (INIS)

    Eberle, H.

    1985-04-01

    In order to further exploit the possibilities of the KfK K-edge densitometer, and to enlarge the range of its application, we have extended and modified the instrument's software. With the new software packages the instrument can now be used for analysis of the actinide elemments Th, U, Np, Pu and Am in single element solutions, and for the simultaneous assay of U and Pu in mixed U/Pu solutions. Provisions have been made for later extensions, allowing the analysis of additional elements combinations, if necessary. The report gives a short description of the new programs, and of the modifications to the previous programs. The listings and the corresponding programs are given in the Appendix. (orig./HP)

  1. Three dimensional mapping of strontium in bone by dual energy K-edge subtraction imaging

    International Nuclear Information System (INIS)

    Cooper, D M L; Chapman, L D; Carter, Y; Zhouping, W; Wu, Y; Panahifar, A; Duke, M J M; Doschak, M; Britz, H M; Bewer, B

    2012-01-01

    The bones of many terrestrial vertebrates, including humans, are continually altered through an internal process of turnover known as remodeling. This process plays a central role in bone adaptation and disease. The uptake of fluorescent tetracyclines within bone mineral is widely exploited as a means of tracking new tissue formation. While investigation of bone microarchitecture has undergone a dimensional shift from 2D to 3D in recent years, we lack a 3D equivalent to fluorescent labeling. In the current study we demonstrate the ability of synchrotron radiation dual energy K-edge subtraction (KES) imaging to map the 3D distribution of elemental strontium within rat vertebral samples. This approach has great potential for ex vivo analysis of preclinical models and human tissue samples. KES also represents a powerful tool for investigating the pharmokinetics of strontium-based drugs recently approved in many countries around the globe for the treatment of osteoporosis. (paper)

  2. Si K EDGE STRUCTURE AND VARIABILITY IN GALACTIC X-RAY BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Norbert S.; Corrales, Lia; Canizares, Claude R. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2016-08-10

    We survey the Si K edge structure in various absorbed Galactic low-mass X-ray binaries (LMXBs) to study states of silicon in the inter- and circum-stellar medium. The bulk of these LMXBs lie toward the Galactic bulge region and all have column densities above 10{sup 22} cm{sup −2}. The observations were performed using the Chandra High Energy Transmission Grating Spectrometer. The Si K edge in all sources appears at an energy value of 1844 ± 0.001 eV. The edge exhibits significant substructure that can be described by a near edge absorption feature at 1849 ± 0.002 eV and a far edge absorption feature at 1865 ± 0.002 eV. Both of these absorption features appear variable with equivalent widths up to several mÅ. We can describe the edge structure using several components: multiple edge functions, near edge absorption excesses from silicates in dust form, signatures from X-ray scattering optical depths, and a variable warm absorber from ionized atomic silicon. The measured optical depths of the edges indicate much higher values than expected from atomic silicon cross sections and interstellar medium abundances, and they appear consistent with predictions from silicate X-ray absorption and scattering. A comparison with models also indicates a preference for larger dust grain sizes. In many cases, we identify Si xiii resonance absorption and determine ionization parameters between log ξ = 1.8 and 2.8 and turbulent velocities between 300 and 1000 km s{sup −1}. This places the warm absorber in close vicinity of the X-ray binaries. In some data, we observe a weak edge at 1.840 keV, potentially from a lesser contribution of neutral atomic silicon.

  3. Demonstration of iodine K-edge imaging by use of an energy-discrimination X-ray computed tomography system with a cadmium telluride detector.

    Science.gov (United States)

    Abudurexiti, Abulajiang; Kameda, Masashi; Sato, Eiichi; Abderyim, Purkhet; Enomoto, Toshiyuki; Watanabe, Manabu; Hitomi, Keitaro; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Takahashi, Kiyomi; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2010-07-01

    An energy-discrimination K-edge X-ray computed tomography (CT) system is useful for increasing the contrast resolution of a target region by utilizing contrast media. The CT system has a cadmium telluride (CdTe) detector, and a projection curve is obtained by linear scanning with use of the CdTe detector in conjunction with an X-stage. An object is rotated by a rotation step angle with use of a turntable between the linear scans. Thus, CT is carried out by repetition of the linear scanning and the rotation of an object. Penetrating X-ray photons from the object are detected by the CdTe detector, and event signals of X-ray photons are produced with use of charge-sensitive and shaping amplifiers. Both the photon energy and the energy width are selected by use of a multi-channel analyzer, and the number of photons is counted by a counter card. For performing energy discrimination, a low-dose-rate X-ray generator for photon counting was developed; the maximum tube voltage and the minimum tube current were 110 kV and 1.0 microA, respectively. In energy-discrimination CT, the tube voltage and the current were 60 kV and 20.0 microA, respectively, and the X-ray intensity was 0.735 microGy/s at 1.0 m from the source and with a tube voltage of 60 kV. Demonstration of enhanced iodine K-edge X-ray CT was carried out by selection of photons with energies just beyond the iodine K-edge energy of 33.2 keV.

  4. Catheter Angiography

    Medline Plus

    Full Text Available ... Angiography is a minimally invasive medical test that helps physicians diagnose and treat medical conditions. Angiography uses ... has narrowed the arteries to the legs and help prepare for endovascular intervention or surgery. detect disease ...

  5. Catheter Angiography

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    Full Text Available ... you are pregnant and discuss any recent illnesses, medical conditions, medications you're taking and allergies, especially ... is Catheter Angiography? Angiography is a minimally invasive medical test that helps physicians diagnose and treat medical ...

  6. Catheter Angiography

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    Full Text Available ... far outweighs the risk. If you have a history of allergy to x-ray contrast material, your ... Angiography (CTA) X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to Catheter Angiography Sponsored ...

  7. Catheter Angiography

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    Full Text Available ... story about radiology? Share your patient story here Images × Image Gallery Interventional radiologist performing an angiography exam View ... ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to Catheter Angiography Sponsored by Please note ...

  8. Catheter Angiography

    Medline Plus

    Full Text Available ... resonance imaging (MRI) In catheter angiography, a thin plastic tube, called a catheter , is inserted into an ... The catheter used in angiography is a long plastic tube about as thick as a strand of ...

  9. Catheter Angiography

    Medline Plus

    Full Text Available ... lies. The catheter used in angiography is a long plastic tube about as thick as a strand of spaghetti. top of page How does the procedure work? Catheter angiography works much the same as a ...

  10. Noncontrast-enhanced magnetic resonance renal angiography using a repetitive artery and venous labelling technique at 3 T: comparison with contrast-enhanced magnetic resonance angiography in subjects with normal renal function.

    Science.gov (United States)

    Park, Sung Yoon; Kim, Chan Kyo; Kim, EunJu; Park, Byung Kwan

    2015-02-01

    To investigate the feasibility of noncontrast-enhanced MR angiography (NC-MRA) using the repetitive artery and venous labelling (RAVEL) technique to evaluate renal arteries compared to contrast-enhanced MR angiography (CE-MRA). Twenty-five subjects with normal renal function underwent NC-MRA using a RAVEL technique and CE-MRA at 3 T. Two independent readers analysed the MRA images. Image quality, number of renal arteries, presence or absence of an early branching vessel, and diameter of the main renal arteries were evaluated. The overall image quality of NC-MRA was fair or greater in 88% of right and 92% of left renal arteries, while it was 96% in both sides with CE-MRA. On NC-MRA, the number of renal arteries in all subjects was perfectly predicted by both readers. Sensitivity and specificity for predicting early branching vessels were 82% and 100% for reader 1 and 82% and 95% for reader 2. Inter-modality agreement for comparing the diameters of main renal arteries was good or excellent at all segments for both readers. Inter-reader agreement was moderate or good at all segments except at the right distal segment on NC-MRA. NC-MRA with the RAVEL technique at 3 T may have comparable diagnostic feasibility for evaluating renal arteries compared to CE-MRA. • Accurate pre-treatment evaluation of renal artery anatomy helps clinical decision-making. • NC-MRA using RAVEL offers acceptable imaging quality for renal artery evaluation. • The 3 T RAVEL technique provides excellent diagnostic performance for renal artery evaluation. • The 3 T RAVEL technique may be an alternative to contrast-enhanced MRA.

  11. Catheter Angiography

    Medline Plus

    Full Text Available ... Z Catheter Angiography Catheter angiography uses a catheter, x-ray imaging guidance and an injection of contrast material ... vessels in the body. Angiography is performed using: x-rays with catheters computed tomography (CT) magnetic resonance imaging ( ...

  12. Structure of spinel at high temperature using in-situ XANES study at the Al and Mg K-edge

    Energy Technology Data Exchange (ETDEWEB)

    Ligny, D de [Universite Claude Bernard Lyon 1, LPCML, 69622 Villeurbanne (France); Neuville, D R [Physique des Mineraux et Magmas, Geochimie-Cosmochimie, CNRS-IPGP, 4 place Jussieu, 75005 Paris (France); Flank, A-M; Lagarde, P, E-mail: deligny@pcml.univ-lyon1.f [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 France (France)

    2009-11-15

    We present structural information obtained on spinel at high temperature (298-2400 K) using in situ XANES at the Mg and Al K-edge. Spinel, {sup [4]}(Al{sub x},Mg{sub 1-x}){sup [6]}(Al{sub 2-x},Mg{sub x})O{sub 4}, with increasing temperature, show a substitution of Mg by Al and Al by Mg in their respective sites. This substitution corresponds to an inversion of the Mg and Al sites. Furthermore, both experiments at the Al and Mg K-edges are in good agreement with XANES calculation made using FDMNES code.

  13. The use of the hybrid K-edge densitometer for routine analysis of safeguards verification samples of reprocessing input liquor

    International Nuclear Information System (INIS)

    Ottmar, H.; Eberle, H.

    1991-01-01

    Following successful tests of a hybrid K-edge instrument at TUI Karlsruhe and the routine use of a K-edge densitometer for safeguards verification at the same laboratory, the Euratom Safeguards Directorate of the Commission of the European Communities decided to install the first such instrument into a large industrial reprocessing plant for the routine verification of samples taken from the input accountancy tanks. This paper reports on the installation, calibration, sample handling procedure and the performance of this instrument after one year of routine operation

  14. Impact of intravascular enhancement, heart rate, and calcium score on diagnostic accuracy in multislice Computed Tomography coronary angiography

    International Nuclear Information System (INIS)

    Cademartiri, Filippo; Mollet, Nico R.; Kriestin, Gabriel P.; Runza, Giuseppe; Bartolotta, Tommaso Vincenzo; Galia, Massimo; Midiri, Massimo; Belgrano, Manuel; Pozzi Mucelli, Roberto

    2005-01-01

    Purpose. To assess the effect of intravascular enhancement, heart rate, and calcium score on diagnostic accuracy in the detection of significant coronary artery stenosis using 16-row multislice computed tomography (MSCT). Materials and methods. One hundred patients (88 males; 59±11 years) with suspected coronary artery disease who had undergone conventional coronary angiography (CA) and MSCT-CA were retrospectively enrolled for the study. Patients underwent a MSCT-CA, with the following protocol: collimation 16x0.75 mm, gantry rotation time 420 ms, feed/rotation 2.8 mm, kV 120, mAs 400-500. The protocol for contrast material administration was 100 ml of Iodixanol 320 mgI/nl at 4 ml/s and the scan delay was defined with a bolus tracking technique. In all patients vascular enhancement was measured in the aortic root, and the left and the right coronary arteries. The average enhancement was used to divide the population in two groups of 50 patients each, one with lower enhancement (Low), and one with higher enhancement (High). In the two groups diagnostic accuracy (per coronary segment) for the detection of significant stenosis (≥50% lumen reduction) was evaluated in vessels ≥2mm in diameter using quantitative CA as the reference standard. The differences in diagnostic accuracy were compared with a Chi-square test and a p [it

  15. Peripheral Vasculature: High-Temporal- and High-Spatial-Resolution Three-dimensional Contrast-enhanced MR Angiography1

    Science.gov (United States)

    Haider, Clifton R.; Glockner, James F.; Stanson, Anthony W.; Riederer, Stephen J.

    2009-01-01

    Purpose: To prospectively evaluate the feasibility of performing high-spatial-resolution (1-mm isotropic) time-resolved three-dimensional (3D) contrast material–enhanced magnetic resonance (MR) angiography of the peripheral vasculature with Cartesian acquisition with projection-reconstruction–like sampling (CAPR) and eightfold accelerated two-dimensional (2D) sensitivity encoding (SENSE). Materials and Methods: All studies were approved by the institutional review board and were HIPAA compliant; written informed consent was obtained from all participants. There were 13 volunteers (mean age, 41.9; range, 27–53 years). The CAPR sequence was adapted to provide 1-mm isotropic spatial resolution and a 5-second frame time. Use of different receiver coil element sizes for those placed on the anterior-to-posterior versus left-to-right sides of the field of view reduced signal-to-noise ratio loss due to acceleration. Results from eight volunteers were rated independently by two radiologists according to prominence of artifact, arterial to venous separation, vessel sharpness, continuity of arterial signal intensity in major arteries (anterior and posterior tibial, peroneal), demarcation of origin of major arteries, and overall diagnostic image quality. MR angiographic results in two patients with peripheral vascular disease were compared with their results at computed tomographic angiography. Results: The sequence exhibited no image artifact adversely affecting diagnostic image quality. Temporal resolution was evaluated to be sufficient in all cases, even with known rapid arterial to venous transit. The vessels were graded to have excellent sharpness, continuity, and demarcation of the origins of the major arteries. Distal muscular branches and the communicating and perforating arteries were routinely seen. Excellent diagnostic quality rating was given for 15 (94%) of 16 evaluations. Conclusion: The feasibility of performing high-diagnostic-quality time-resolved 3D

  16. Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Kevin H.

    2014-07-14

    Some polymer properties, such as conductivity, are very sensitive to short- and intermediate-range orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.

  17. New K-edge-balanced contrast phantom for image quality assurance in projection radiography

    Science.gov (United States)

    Cresens, Marc; Schaetzing, Ralph

    2003-06-01

    X-ray-absorber step-wedge phantoms serve in projection radiography to assess a detection system's overall exposure-related signal-to-noise ratio performance and contrast response. Data derived from a phantom image, created by exposing a step-wedge onto the image receptor, are compared with predefined acceptance criteria during periodic image quality assurance (QA). For contrast-related measurements, in particular, the x-ray tube potential requires accurate setting and low ripple, since small deviations from the specified kVp, causing energy spectrum changes, lead to significant image signal variation at high contrast ratios. A K-edge-balanced, rare-earth-metal contrast phantom can generate signals that are significantly more robust to the spectral variability and instability of exposure equipment in the field. The image signals from a hafnium wedge, for example, are up to eight times less sensitive to spectral fluctuations than those of today"s copper phantoms for a 200:1 signal ratio. At 120 kVp (RQA 9), the hafnium phantom still preserves 70% of the subject contrast present at 75 kVp (RQA 5). A copper wedge preserves only 7% of its contrast over the same spectral range. Spectral simulations and measurements on prototype systems, as well as potential uses of this new class of phantoms (e.g., QA, single-shot exposure response characterization) are described.

  18. Surface modification study of borate materials from B K-edge X-ray absorption spectroscopy

    Science.gov (United States)

    Kasrai, Masoud; Fleet, Michael E.; Muthupari, Swaminathan; Li, D.; Bancroft, G. M.

    The B K-edge X-ray absorption near-edge structure (XANES) spectra of two borates with tetrahedrally-coordinated B [[4]B; natural danburite (CaB2Si2O8) and synthetic boron phosphate (BPO4)] have been recorded in total electron yield (TEY) and fluorescence yield (FY) modes to investigate the surface and bulk structure of these materials. The TEY XANES measurement shows that danburite is susceptible to surface damage involving conversion of [4]B sites to [3]B sites by reaction with moisture and/or mechanical abrasion (grinding, polishing, etc.). The bulk of the mineral is essentially unaffected. Commercial boron phosphate powder exhibits more extensive surface and bulk damage, which increases with air exposure but is recovered on heating at 650°C. In contrast to ELNES, the XANES technique is not affected by beam damage and when collected in the FY mode is capable of yielding meaningful information on the coordination and intermediate-range structure of B in borate and borosilicate materials.

  19. The optical properties of boron carbide near boron K-edge inside periodical multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ksenzov, Dmitriy; Schlemper, Christoph; Pietsch, Ullrich [University of Siegen (Germany)

    2010-07-01

    Multilayer mirrors made for the use in the wavelength range near K-edge of boron (188 eV) are of great interest for X-ray fluorescence analysis of boron content in doped semiconductors, plasma diagnostics, astronomy and lithography. Moreover, multilayer mirrors composed by a metal and a low Z element like boron are used as optical elements in both the soft x-ray spectral range as well as at higher photon energies on 3rd generation synchrotron beamlines. Using an energy-resolved photon-in-photon-out method we reconstructed the optical data from energy dependence of both integrated peak intensity and FWHM of the 1st order ML Bragg peak measured at the UHV triple axis soft-x-ray reflectometer at BESSY II. The experiments clearly demonstrate that the peak shape of the ML Bragg peak is most sensitive to any kind of electronic excitation and recombination in solid. The soft-ray reflectivity can give detailed information for MLs with thickness up to several tens of nanometers. In addition, measurements close to a resonance edge probe the chemical state of the respective constituent accompanied with a high sensitivity of changes close to the sample surface.

  20. The local structure of CaNa pyroxenes. I. XANES study at the Na K-edge

    International Nuclear Information System (INIS)

    Mottana, Annibale; Murata, T.; Wu, Ziyu; Marcelli, Augusto; Paris, E.

    1996-07-01

    X-ray absorption Na K-edge spectra have been recorded on synthetic end member jadeite and on a series of natural Ca-Na pyroxenes compositionally straddling the Jd-Di. The disordered C2/c members of the series are systematically different from the ordered P2/n members. These differences can be interpreted and explained by comparing the experimental spectra with theoretical spectra. These have been calculated by the multiple-scattering formalism from the atomic positional parameters determined by single-crystal X-ray diffraction structure refinement on the same samples. In the full multiple scattering region of the spectrum (1075 to 1095 eV) C-pyroxenes exhibit three features which reflect the 6-2 configuration of the O back-scattering atoms around the Na absorber located at the center of the cluster (site M2 of the jadeite structure). P-pyroxenes show more complicated spectra in which at least four features can be recognized; they reflect the two types of the configuration (6-2 and 4-2-2) of the oxygens around Na in the two independent M2 and M21 eight-fold coordinated sites of the omphacite structure. A weak, sometimes poorly resolved peak at 1079 eV diagnostic and discriminates C- from P-pyroxenes. The Garnet Ridge C2/c impure jadeite exhibits a spectrum which is intermediate between those of jadeite and omphacite. The Hedin-Lundqist potential proves best for these insulating materials and allows multiple-scattering calculations agreeing well with experiments. The assessment of the local electronic properties of compositionally and structurally complex minerals such as clinopyroxenes is thus enhanced

  1. The local structure of Ca{sub N}a pyroxenes. I. XANES study at the Na K-edge

    Energy Technology Data Exchange (ETDEWEB)

    Mottana, Annibale [Rome, Univ. III (Italy). Dipt. di Scienze Geologiche; Murata, T. [Kyoto, Univ. of Education (Japan). Dept. of Physics; Wu, Ziyu; Marcelli, Augusto [INFN, Frascati (Italy). Laboratori Nazionali di Frascati; Paris, E. [Camerino, Univ. (Italy). Dipt. di Scienze della Terra

    1996-07-01

    X-ray absorption Na K-edge spectra have been recorded on synthetic end member jadeite and on a series of natural Ca-Na pyroxenes compositionally straddling the Jd-Di. The disordered C2/c members of the series are systematically different from the ordered P2/n members. These differences can be interpreted and explained by comparing the experimental spectra with theoretical spectra. These have been calculated by the multiple-scattering formalism from the atomic positional parameters determined by single-crystal X-ray diffraction structure refinement on the same samples. In the full multiple scattering region of the spectrum (1075 to 1095 eV) C-pyroxenes exhibit three features which reflect the 6-2 configuration of the O back-scattering atoms around the Na absorber located at the center of the cluster (site M2 of the jadeite structure). P-pyroxenes show more complicated spectra in which at least four features can be recognized; they reflect the two types of the configuration (6-2 and 4-2-2) of the oxygens around Na in the two independent M2 and M21 eight-fold coordinated sites of the omphacite structure. A weak, sometimes poorly resolved peak at 1079 eV diagnostic and discriminates C- from P-pyroxenes. The Garnet Ridge C2/c impure jadeite exhibits a spectrum which is intermediate between those of jadeite and omphacite. The Hedin-Lundqist potential proves best for these insulating materials and allows multiple-scattering calculations agreeing well with experiments. The assessment of the local electronic properties of compositionally and structurally complex minerals such as clinopyroxenes is thus enhanced.

  2. Clinical performance of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced pediatric abdominal MR angiography.

    Science.gov (United States)

    Zhang, Tao; Yousaf, Ufra; Hsiao, Albert; Cheng, Joseph Y; Alley, Marcus T; Lustig, Michael; Pauly, John M; Vasanawala, Shreyas S

    2015-10-01

    Pediatric contrast-enhanced MR angiography is often limited by respiration, other patient motion and compromised spatiotemporal resolution. To determine the reliability of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography method for depicting abdominal arterial anatomy in young children. With IRB approval and informed consent, we retrospectively identified 27 consecutive children (16 males and 11 females; mean age: 3.8 years, range: 14 days to 8.4 years) referred for contrast-enhanced MR angiography at our institution, who had undergone free-breathing spatiotemporally accelerated time-resolved contrast-enhanced MR angiography studies. A radio-frequency-spoiled gradient echo sequence with Cartesian variable density k-space sampling and radial view ordering, intrinsic motion navigation and intermittent fat suppression was developed. Images were reconstructed with soft-gated parallel imaging locally low-rank method to achieve both motion correction and high spatiotemporal resolution. Quality of delineation of 13 abdominal arteries in the reconstructed images was assessed independently by two radiologists on a five-point scale. Ninety-five percent confidence intervals of the proportion of diagnostically adequate cases were calculated. Interobserver agreements were also analyzed. Eleven out of 13 arteries achieved acceptable image quality (mean score range: 3.9-5.0) for both readers. Fair to substantial interobserver agreement was reached on nine arteries. Free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography frequently yields diagnostic image quality for most abdominal arteries in young children.

  3. Clinical performance of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced pediatric abdominal MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tao; Cheng, Joseph Y. [Stanford University, Department of Radiology, Stanford, CA (United States); Stanford University, Department of Electrical Engineering, Stanford, CA (United States); Yousaf, Ufra; Alley, Marcus T.; Vasanawala, Shreyas S. [Stanford University, Department of Radiology, Stanford, CA (United States); Hsiao, Albert [University of California, San Diego, Department of Radiology, San Diego, CA (United States); Lustig, Michael [Stanford University, Department of Electrical Engineering, Stanford, CA (United States); University of California, Berkeley, Department of Electrical Engineering and Computer Sciences, Berkeley, CA (United States); Pauly, John M. [Stanford University, Department of Electrical Engineering, Stanford, CA (United States)

    2015-10-15

    Pediatric contrast-enhanced MR angiography is often limited by respiration, other patient motion and compromised spatiotemporal resolution. To determine the reliability of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography method for depicting abdominal arterial anatomy in young children. With IRB approval and informed consent, we retrospectively identified 27 consecutive children (16 males and 11 females; mean age: 3.8 years, range: 14 days to 8.4 years) referred for contrast-enhanced MR angiography at our institution, who had undergone free-breathing spatiotemporally accelerated time-resolved contrast-enhanced MR angiography studies. A radio-frequency-spoiled gradient echo sequence with Cartesian variable density k-space sampling and radial view ordering, intrinsic motion navigation and intermittent fat suppression was developed. Images were reconstructed with soft-gated parallel imaging locally low-rank method to achieve both motion correction and high spatiotemporal resolution. Quality of delineation of 13 abdominal arteries in the reconstructed images was assessed independently by two radiologists on a five-point scale. Ninety-five percent confidence intervals of the proportion of diagnostically adequate cases were calculated. Interobserver agreements were also analyzed. Eleven out of 13 arteries achieved acceptable image quality (mean score range: 3.9-5.0) for both readers. Fair to substantial interobserver agreement was reached on nine arteries. Free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography frequently yields diagnostic image quality for most abdominal arteries in young children. (orig.)

  4. Clinical performance of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced pediatric abdominal MR angiography

    International Nuclear Information System (INIS)

    Zhang, Tao; Cheng, Joseph Y.; Yousaf, Ufra; Alley, Marcus T.; Vasanawala, Shreyas S.; Hsiao, Albert; Lustig, Michael; Pauly, John M.

    2015-01-01

    Pediatric contrast-enhanced MR angiography is often limited by respiration, other patient motion and compromised spatiotemporal resolution. To determine the reliability of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography method for depicting abdominal arterial anatomy in young children. With IRB approval and informed consent, we retrospectively identified 27 consecutive children (16 males and 11 females; mean age: 3.8 years, range: 14 days to 8.4 years) referred for contrast-enhanced MR angiography at our institution, who had undergone free-breathing spatiotemporally accelerated time-resolved contrast-enhanced MR angiography studies. A radio-frequency-spoiled gradient echo sequence with Cartesian variable density k-space sampling and radial view ordering, intrinsic motion navigation and intermittent fat suppression was developed. Images were reconstructed with soft-gated parallel imaging locally low-rank method to achieve both motion correction and high spatiotemporal resolution. Quality of delineation of 13 abdominal arteries in the reconstructed images was assessed independently by two radiologists on a five-point scale. Ninety-five percent confidence intervals of the proportion of diagnostically adequate cases were calculated. Interobserver agreements were also analyzed. Eleven out of 13 arteries achieved acceptable image quality (mean score range: 3.9-5.0) for both readers. Fair to substantial interobserver agreement was reached on nine arteries. Free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced MR angiography frequently yields diagnostic image quality for most abdominal arteries in young children. (orig.)

  5. K-edge resonant x-ray magnetic scattering from a transition-metal oxide: NiO

    DEFF Research Database (Denmark)

    Hill, J.P.; Kao, C.C.; McMorrow, D.F.

    1997-01-01

    We report the observation of resonant x-ray magnetic scattering in the vicinity of the Ni K edge in the antiferromagnet NiO. An approximately twofold increase in the scattering is observed as the incident photon energy is tuned through a pre-edge feature in the absorption spectrum, associated...

  6. Off-line NDA measurement of actinides in reprocessing solution using hybrid K-edge/K-XRF densitometer

    International Nuclear Information System (INIS)

    Bootharajan, M.; Swaminathan, K.; Venkata Subramani, C.R.; Kumar, R.

    2015-01-01

    A versatile, nondestructive assay (NDA) system of a hybrid K-edge/K-XRF facility adapted to a glove box facility has been developed at RCL, IGCAR for the analysis of U and Pu in process solutions obtained from the reprocessing of spent nuclear fuels. This paper describes i) The development of a hybrid K-edge/K-XRF facility adapted to a glove box system ii) The results obtained using conditioner solution of burn up 155 GWd/t with a dose of 20 R/h and iii) Comparison of the results with the parallel analyses of the same by Isotope dilution mass spectrometry. The hybrid K-edge cum K-XRF densitometer is ideally suited for dissolver solutions as well as U and Pu product solutions from reprocessing plant. This method can be useful in the analysis of mixed solution of Special Nuclear Materials (SNM) without chemical separation. To assay solutions with high radiation background, the hybrid K-edge/K-XRF system is designed and fabricated inside a glove box with adequate shielding from both source X-rays and the sample radiation. The theory and preliminary experiments are described elsewhere. Around 5 mL of the conditioner solution (burn up of 155 GWd/t with a dose of 20 R/h) was taken in a poly propylene vial placed concentrically in to another poly propylene vial. The concentration was estimated by K-edge densitometry with X-ray tube operated with 150 kV and 1 mA and counting period of 3000s. Background correction was obtained with the X-ray tube in OFF condition. The solution was analysed parallelly using isotopic dilution mass spectrometry

  7. Catheter Angiography

    Medline Plus

    Full Text Available ... medical test that helps physicians diagnose and treat medical conditions. Angiography uses one of three imaging technologies and, in most cases, a contrast material injection ...

  8. Contrast enhanced renal MR angiography at 7 Tesla: How much gadolinium do we need?

    Energy Technology Data Exchange (ETDEWEB)

    Beiderwellen, Karsten, E-mail: karsten.beiderwellen@uni-due.de [Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen (Germany); Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany); Kraff, Oliver, E-mail: Oliver.kraff@uni-due.de [Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany); Laader, Anja, E-mail: anja.laader@uk-essen.de [Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen (Germany); Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany); Maderwald, Stefan, E-mail: Stefan.maderwald@uni-due.de [Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany); Orzada, Stephan, E-mail: Stephan.orzada@uni-due.de [Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany); Ladd, Mark E., E-mail: mark.ladd@dkfz-heidelberg.de [Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg (Germany); Forsting, Michael, E-mail: Michael.forsting@uk-essen.de [Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen (Germany); Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany); Lauenstein, Thomas C., E-mail: Thomas.Lauenstein@uni-due.de [Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen (Germany); Umutlu, Lale, E-mail: Lale.umutlu@uk-essen.de [Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen (Germany); Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany)

    2017-01-15

    Objectives: To investigate whether a dose reduction of Gadobutrol for renal magnetic resonance angiography (MRA) at 7 Tesla (T) is feasible while preserving diagnostic image quality. Methods: Ten healthy volunteers were enrolled for a renal MRA on a 7 T scanner. Fast low angle shot (FLASH) MRA data sets were obtained utilizing three different doses of Gadobutrol (0.1, 0.05 and 0.025 mmol/kg body weight [BW]). Contrast ratios (CR) were measured in the aorta as well as in the intra- and extraparenchymal arteries compared to the psoas muscle. Qualitative analysis regarding the delineation of vessel structures was performed using a four-point-scale. Results: All doses of Gadobutrol allowed for a good delineation of the aorta and renal arteries. For the extra- and intraparenchymal segmental arteries higher values were observed for full and half dose in comparison to quarter dose. No significant difference was observed for full and half dose. A lower CR was observed for quarter compared to half dose (p < 0.05) for the renal arteries. Conclusions: While best results were observed for half and full dose, a dose reduction to 0.025 mmol/kg BW is justifiable, maintaining a diagnostic image quality. This may be of high interest considering patients with renal impairment.

  9. Assessment of chronic thromboembolic pulmonary hypertension by three-dimensional contrast-enhanced MR angiography - comparison with selective intraarterial DSA

    International Nuclear Information System (INIS)

    Kreitner, K.F.; Ley, S.; Kauczor, H.U.; Kalden, P.; Pitton, M.B.; Thelen, M.; Mayer, E.; Laub, G.

    2000-01-01

    Purpose: This study compares contrast-enhanced 3D-MR angiography (MRA) of the pulmonary arteries with selective intraarterial DSA in patients with chronic thromboembolic pulmonary hypertension. Materials and methods: 20 patients preoperatively underwent a contrast-enhanced 3D-MRA of the pulmonary arteries at 1.5 T using the phased-array body coil. For MRA, we used a 3D-Flash-sequence after bolus timing. 2 radiologists analyzed the acquired image material in consensus with respect to the detection of central thromboembolic material and the visualization of the pulmonary arterial tree. Finally, the MR angiograms were compared with selective DSA images using surgical findings as the definitive standard. Results: MRA demonstrated central thromboembolic material, vessel cut-offs and abnormal proximal-to-distal tapering in all patients. Compared to DSA, MRA depicted the pulmonary vessels up to the segmental level in all cases, it was inferior to DSA in delineation of the subsegmental arteries (sensitivity 87%, specificity 100%). The central beginning of the thromboembolic occlusions seen at MRA corresponded to the beginning of the deobliteration procedure during pulmonary thromboendarterectomy in every case. (orig.) [de

  10. Space-time relationship in continuously moving table method for large FOV peripheral contrast-enhanced magnetic resonance angiography

    International Nuclear Information System (INIS)

    Sabati, M; Lauzon, M L; Frayne, R

    2003-01-01

    Data acquisition using a continuously moving table approach is a method capable of generating large field-of-view (FOV) 3D MR angiograms. However, in order to obtain venous contamination-free contrast-enhanced (CE) MR angiograms in the lower limbs, one of the major challenges is to acquire all necessary k-space data during the restricted arterial phase of the contrast agent. Preliminary investigation on the space-time relationship of continuously acquired peripheral angiography is performed in this work. Deterministic and stochastic undersampled hybrid-space (x, k y , k z ) acquisitions are simulated for large FOV peripheral runoff studies. Initial results show the possibility of acquiring isotropic large FOV images of the entire peripheral vascular system. An optimal trade-off between the spatial and temporal sampling properties was found that produced a high-spatial resolution peripheral CE-MR angiogram. The deterministic sampling pattern was capable of reconstructing the global structure of the peripheral arterial tree and showed slightly better global quantitative results than stochastic patterns. Optimal stochastic sampling patterns, on the other hand, enhanced small vessels and had more favourable local quantitative results. These simulations demonstrate the complex spatial-temporal relationship when sampling large FOV peripheral runoff studies. They also suggest that more investigation is required to maximize image quality as a function of hybrid-space coverage, acquisition repetition time and sampling pattern parameters

  11. Max CAPR: high-resolution 3D contrast-enhanced MR angiography with acquisition times under 5 seconds.

    Science.gov (United States)

    Haider, Clifton R; Borisch, Eric A; Glockner, James F; Mostardi, Petrice M; Rossman, Phillip J; Young, Phillip M; Riederer, Stephen J

    2010-10-01

    High temporal and spatial resolution is desired in imaging of vascular abnormalities having short arterial-to-venous transit times. Methods that exploit temporal correlation to reduce the observed frame time demonstrate temporal blurring, obfuscating bolus dynamics. Previously, a Cartesian acquisition with projection reconstruction-like (CAPR) sampling method has been demonstrated for three-dimensional contrast-enhanced angiographic imaging of the lower legs using two-dimensional sensitivity-encoding acceleration and partial Fourier acceleration, providing 1mm isotropic resolution of the calves, with 4.9-sec frame time and 17.6-sec temporal footprint. In this work, the CAPR acquisition is further undersampled to provide a net acceleration approaching 40 by eliminating all view sharing. The tradeoff of frame time and temporal footprint in view sharing is presented and characterized in phantom experiments. It is shown that the resultant 4.9-sec acquisition time, three-dimensional images sets have sufficient spatial and temporal resolution to clearly portray arterial and venous phases of contrast passage. It is further hypothesized that these short temporal footprint sequences provide diagnostic quality images. This is tested and shown in a series of nine contrast-enhanced MR angiography patient studies performed with the new method.

  12. Evaluation of fast highly undersampled contrast-enhanced MR angiography (sparse CE-MRA) in intracranial applications - initial study

    International Nuclear Information System (INIS)

    Gratz, Marcel; Quick, Harald H.; Schlamann, Marc; Goericke, Sophia; Maderwald, Stefan

    2017-01-01

    To assess the image quality of sparsely sampled contrast-enhanced MR angiography (sparse CE-MRA) providing high spatial resolution and whole-head coverage. Twenty-three patients scheduled for contrast-enhanced MR imaging of the head, (N = 19 with intracranial pathologies, N = 9 with vascular diseases), were included. Sparse CE-MRA at 3 Tesla was conducted using a single dose of contrast agent. Two neuroradiologists independently evaluated the data regarding vascular visibility and diagnostic value of overall 24 parameters and vascular segments on a 5-point ordinary scale (5 = very good, 1 = insufficient vascular visibility). Contrast bolus timing and the resulting arterio-venous overlap was also evaluated. Where available (N = 9), sparse CE-MRA was compared to intracranial Time-of-Flight MRA. The overall rating across all patients for sparse CE-MRA was 3.50 ± 1.07. Direct influence of the contrast bolus timing on the resulting image quality was observed. Overall mean vascular visibility and image quality across different features was rated good to intermediate (3.56 ± 0.95). The average performance of intracranial Time-of-Flight was rated 3.84 ± 0.87 across all patients and 3.54 ± 0.62 across all features. Sparse CE-MRA provides high-quality 3D MRA with high spatial resolution and whole-head coverage within short acquisition time. Accurate contrast bolus timing is mandatory. (orig.)

  13. Evaluation of fast highly undersampled contrast-enhanced MR angiography (sparse CE-MRA) in intracranial applications - initial study

    Energy Technology Data Exchange (ETDEWEB)

    Gratz, Marcel; Quick, Harald H. [University of Duisburg-Essen, Erwin L. Hahn Institute for MR Imaging, Essen (Germany); University Hospital Essen, High Field and Hybrid MR Imaging, Essen (Germany); Schlamann, Marc [University Hospital Giessen and Marburg GmbH, Neuroradiology, Giessen (Germany); University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Goericke, Sophia [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Maderwald, Stefan [University of Duisburg-Essen, Erwin L. Hahn Institute for MR Imaging, Essen (Germany)

    2017-03-15

    To assess the image quality of sparsely sampled contrast-enhanced MR angiography (sparse CE-MRA) providing high spatial resolution and whole-head coverage. Twenty-three patients scheduled for contrast-enhanced MR imaging of the head, (N = 19 with intracranial pathologies, N = 9 with vascular diseases), were included. Sparse CE-MRA at 3 Tesla was conducted using a single dose of contrast agent. Two neuroradiologists independently evaluated the data regarding vascular visibility and diagnostic value of overall 24 parameters and vascular segments on a 5-point ordinary scale (5 = very good, 1 = insufficient vascular visibility). Contrast bolus timing and the resulting arterio-venous overlap was also evaluated. Where available (N = 9), sparse CE-MRA was compared to intracranial Time-of-Flight MRA. The overall rating across all patients for sparse CE-MRA was 3.50 ± 1.07. Direct influence of the contrast bolus timing on the resulting image quality was observed. Overall mean vascular visibility and image quality across different features was rated good to intermediate (3.56 ± 0.95). The average performance of intracranial Time-of-Flight was rated 3.84 ± 0.87 across all patients and 3.54 ± 0.62 across all features. Sparse CE-MRA provides high-quality 3D MRA with high spatial resolution and whole-head coverage within short acquisition time. Accurate contrast bolus timing is mandatory. (orig.)

  14. Catheter Angiography

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Catheter Angiography Catheter angiography ...

  15. Catheter Angiography

    Medline Plus

    Full Text Available ... further information please consult the ACR Manual on Contrast Media and its references. The risk of serious allergic ... View full size with caption Related Articles and Media Angioplasty and Vascular Stenting MR Angiography (MRA) Contrast Materials CT Angiography (CTA) X-ray, Interventional Radiology ...

  16. Catheter Angiography

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... Catheter Angiography? Angiography is a minimally invasive medical test that helps physicians diagnose and treat medical conditions. ...

  17. 3D non-contrast-enhanced ECG-gated MR angiography of the lower extremities with dual-source radiofrequency transmission at 3.0 T: Intraindividual comparison with contrast-enhanced MR angiography in PAOD patients.

    Science.gov (United States)

    Rasper, Michael; Wildgruber, Moritz; Settles, Marcus; Eckstein, Hans-Henning; Zimmermann, Alexander; Reeps, Christian; Rummeny, Ernst J; Huber, Armin M

    2016-09-01

    To compare prospectively image quality and diagnostic confidence of flow-sensitive 3D turbo spin echo (TSE)-based non-contrast-enhanced MR angiography (NE-MRA) at 3.0 T using dual-source radiofrequency (RF) transmission with contrast-enhanced MRA (CE-MRA) in patients with peripheral arterial occlusive disease (PAOD). After consent was obtained, 35 patients (mean age 69.1 ± 10.6 years) with PAOD stage II-IV underwent NE-MRA followed by CE-MRA. Signal-to-noise ratio and contrast-to-noise ratio were calculated. Subjective image quality was independently assessed by two radiologists and stenosis scoring was performed in 875 arterial segments. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for stenosis classification were calculated using CE-MRA as a reference method. Diagnostic agreement with CE-MRA was evaluated with Cohen's kappa statistics. NE-MRA provided high objective and subjective image quality at all levels of the arterial tree. Sensitivity and specificity for the detection of relevant stenosis was 91 % and 89 %, respectively; the NPV was 96 % and the PPV 78 %. There was good concordance between CE-MRA and NE-MRA in stenosis scoring. 3D electrocardiography (ECG)-gated TSE NE-MRA with patient-adaptive dual-source RF transmission at 3.0 T is a promising alternative for PAOD patients with contraindications for gadolinium-based contrast agents. It offers high sensitivity and NPV values in the detection of clinically relevant arterial stenosis. • Flow-sensitive TSE NE-MRA is a promising technique for PAOD evaluation. • Diagnostic accuracy is comparable to contrast-enhanced MRA. • NE-MRA eliminates the risk of NSF in patients with renal insufficiency. • Costs arising from the use of contrast agents can be avoided.

  18. Assessment of myocardial enhancement during coronary CT angiography in critically ill patients

    Energy Technology Data Exchange (ETDEWEB)

    Mírka, Hynek, E-mail: mirka@fnplzen.cz [Department of Imaging Methods, Faculty of Medicine and University Teaching Hospital in Pilsen, Alej Svobody 80, 304 60 Plzeň (Czech Republic); Biomedical Centre, Faculty of Medicine in Plzen, Charles University in Prague, Alej Svobody 76, 304 60 Plzeň (Czech Republic); Ferda, Jiří, E-mail: ferda@fnplzen.cz [Department of Imaging Methods, Faculty of Medicine and University Teaching Hospital in Pilsen, Alej Svobody 80, 304 60 Plzeň (Czech Republic); Baxa, Jan, E-mail: baxaj@fnplzen.cz [Department of Imaging Methods, Faculty of Medicine and University Teaching Hospital in Pilsen, Alej Svobody 80, 304 60 Plzeň (Czech Republic)

    2016-10-15

    Highlights: • There are still unmet needs for the imaging, such as conditions with unknown cause that are not associated with dominant symptoms indicating primarily cardiac cause. • The contribution of the myocardial enhancement evaluation improves to determining the diagnosis of acute myocardial injury and choosing appropriate treatment. • When incorporating the myocardial enhancement assessment into the imaging algorithm, emphasis is placed on a uniform evaluation approach. • The color coded images of the myocardial enhancement in emergency situations help identify the most serious pathologies and shorten the time to adequate therapy. - Abstract: There are still challenges and unmet needs for the imaging techniques, such as conditions of uncertain origin in patients with clinically serious, life-threatening conditions with unknown cause that are not associated with dominant chest pain, ECG changes or other symptoms indicating a possible primarily cardiac or coronary cause. The contribution of the myocardial enhancement evaluation of urgent cardiac CTA scans significantly improves to determining the diagnosis of acute myocardial injury and choosing appropriate treatment. When incorporating the myocardial enhancement assessment into the imaging algorithm of an emergency department, emphasis is placed on a uniform imaging procedure and a uniform evaluation approach. The color coded images of the myocardial enhancement in emergency situations helps identify the most serious pathologies and shorten the time to adequate targeted therapy in patients.

  19. Assessment of myocardial enhancement during coronary CT angiography in critically ill patients

    International Nuclear Information System (INIS)

    Mírka, Hynek; Ferda, Jiří; Baxa, Jan

    2016-01-01

    Highlights: • There are still unmet needs for the imaging, such as conditions with unknown cause that are not associated with dominant symptoms indicating primarily cardiac cause. • The contribution of the myocardial enhancement evaluation improves to determining the diagnosis of acute myocardial injury and choosing appropriate treatment. • When incorporating the myocardial enhancement assessment into the imaging algorithm, emphasis is placed on a uniform evaluation approach. • The color coded images of the myocardial enhancement in emergency situations help identify the most serious pathologies and shorten the time to adequate therapy. - Abstract: There are still challenges and unmet needs for the imaging techniques, such as conditions of uncertain origin in patients with clinically serious, life-threatening conditions with unknown cause that are not associated with dominant chest pain, ECG changes or other symptoms indicating a possible primarily cardiac or coronary cause. The contribution of the myocardial enhancement evaluation of urgent cardiac CTA scans significantly improves to determining the diagnosis of acute myocardial injury and choosing appropriate treatment. When incorporating the myocardial enhancement assessment into the imaging algorithm of an emergency department, emphasis is placed on a uniform imaging procedure and a uniform evaluation approach. The color coded images of the myocardial enhancement in emergency situations helps identify the most serious pathologies and shorten the time to adequate targeted therapy in patients.

  20. Probing single magnon excitations in Sr₂IrO₄ using O K-edge resonant inelastic x-ray scattering.

    Science.gov (United States)

    Liu, X; Dean, M P M; Liu, J; Chiuzbăian, S G; Jaouen, N; Nicolaou, A; Yin, W G; Rayan Serrao, C; Ramesh, R; Ding, H; Hill, J P

    2015-05-27

    Resonant inelastic x-ray scattering (RIXS) at the L-edge of transition metal elements is now commonly used to probe single magnon excitations. Here we show that single magnon excitations can also be measured with RIXS at the K-edge of the surrounding ligand atoms when the center heavy metal elements have strong spin-orbit coupling. This is demonstrated with oxygen K-edge RIXS experiments on the perovskite Sr2IrO4, where low energy peaks from single magnon excitations were observed. This new application of RIXS has excellent potential to be applied to a wide range of magnetic systems based on heavy elements, for which the L-edge RIXS energy resolution in the hard x-ray region is usually poor.

  1. Sulfur K-edge X-ray absorption spectroscopy as an experimental probe for S-nitroso proteins

    International Nuclear Information System (INIS)

    Szilagyi, Robert K.; Schwab, David E.

    2005-01-01

    X-ray absorption spectroscopy at the sulfur K-edge (2.4-2.6 keV) provides a sensitive and specific technique to identify S-nitroso compounds, which have significance in nitric oxide-based cell signaling. Unique spectral features clearly distinguish the S-nitroso-form of a cysteine residue from the sulfhydryl-form or from a methionine thioether. Comparison of the sulfur K-edge spectra of thiolate, thiol, thioether, and S-nitroso thiolate compounds indicates high sensitivity of energy positions and intensities of XAS pre-edge features as determined by the electronic environment of the sulfur absorber. A new experimental setup is being developed for reaching the in vivo concentration range of S-nitroso thiol levels in biological samples

  2. Sequential gadolinium-enhanced magnetic resonance angiography of the aortoiliac and the femoropopliteal arteries with repetitive administration of low-dose contrast agent

    International Nuclear Information System (INIS)

    Ito, Koichiro; Kumazaki, Tatsuo

    2000-01-01

    To obtain a wide-range contrast MR angiography in a single examination, we performed two sequential administrations of low-dose (0.08 mmol/kg) gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) with three dimensional inversion recovery prepared fast spoiled gradient recalled acquisition in the steady-state (3D IR-fast SPGR) sequence. Signal characteristics of the sequence were estimated by computed simulations and an in vitro study. A clinical study of 19 examinations was done with sequential MR angiography of the aortoiliac and femoropopliteal arteries. Great signal differences were observed between the high and low Gd concentrations. Higher Gd concentrations generated significantly stronger signals. Greater signals were produced at TIs of longer than 150 msec than at shorter than 100 msec. In the clinical study, the arteries were visualized with sufficient signals even with a small amount of contrast agent. Contrast-to-noise ratios between the arteries and surrounding skeletal muscles or fat tissues ranged from 10.5±9.6 to 4.7±2.2 and 6.6±2.8 to -3.1±11.2, respectively. No venous enhancement was found with diluted contrast agent on the second MR angiography. Two consecutive contrast MR angiographies can be obtained with repetitive administration of low-dose contrast agent. (author)

  3. Sequential gadolinium-enhanced magnetic resonance angiography of the aortoiliac and the femoropopliteal arteries with repetitive administration of low-dose contrast agent

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Koichiro [Nippon Medical School, Inba, Chiba (Japan). Chiba Hokusoh Hospital; Kumazaki, Tatsuo

    2000-12-01

    To obtain a wide-range contrast MR angiography in a single examination, we performed two sequential administrations of low-dose (0.08 mmol/kg) gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) with three dimensional inversion recovery prepared fast spoiled gradient recalled acquisition in the steady-state (3D IR-fast SPGR) sequence. Signal characteristics of the sequence were estimated by computed simulations and an in vitro study. A clinical study of 19 examinations was done with sequential MR angiography of the aortoiliac and femoropopliteal arteries. Great signal differences were observed between the high and low Gd concentrations. Higher Gd concentrations generated significantly stronger signals. Greater signals were produced at TIs of longer than 150 msec than at shorter than 100 msec. In the clinical study, the arteries were visualized with sufficient signals even with a small amount of contrast agent. Contrast-to-noise ratios between the arteries and surrounding skeletal muscles or fat tissues ranged from 10.5{+-}9.6 to 4.7{+-}2.2 and 6.6{+-}2.8 to -3.1{+-}11.2, respectively. No venous enhancement was found with diluted contrast agent on the second MR angiography. Two consecutive contrast MR angiographies can be obtained with repetitive administration of low-dose contrast agent. (author)

  4. The benefit of non contrast-enhanced magnetic resonance angiography for predicting vascular access surgery outcome: a computer model perspective.

    Directory of Open Access Journals (Sweden)

    Maarten A G Merkx

    Full Text Available INTRODUCTION: Vascular access (VA surgery, a prerequisite for hemodialysis treatment of end-stage renal-disease (ESRD patients, is hampered by complication rates, which are frequently related to flow enhancement. To assist in VA surgery planning, a patient-specific computer model for postoperative flow enhancement was developed. The purpose of this study is to assess the benefit of non contrast-enhanced magnetic resonance angiography (NCE-MRA data as patient-specific geometrical input for the model-based prediction of surgery outcome. METHODS: 25 ESRD patients were included in this study. All patients received a NCE-MRA examination of the upper extremity blood vessels in addition to routine ultrasound (US. Local arterial radii were assessed from NCE-MRA and converted to model input using a linear fit per artery. Venous radii were determined with US. The effect of radius measurement uncertainty on model predictions was accounted for by performing Monte-Carlo simulations. The resulting flow prediction interval of the computer model was compared with the postoperative flow obtained from US. Patients with no overlap between model-based prediction and postoperative measurement were further analyzed to determine whether an increase in geometrical detail improved computer model prediction. RESULTS: Overlap between postoperative flows and model-based predictions was obtained for 71% of patients. Detailed inspection of non-overlapping cases revealed that the geometrical details that could be assessed from NCE-MRA explained most of the differences, and moreover, upon addition of these details in the computer model the flow predictions improved. CONCLUSIONS: The results demonstrate clearly that NCE-MRA does provide valuable geometrical information for VA surgery planning. Therefore, it is recommended to use this modality, at least for patients at risk for local or global narrowing of the blood vessels as well as for patients for whom an US-based model

  5. Feasibility study of X-ray K-edge analysis of RCRA heavy metal contamination of sludge packaged in drums

    International Nuclear Information System (INIS)

    Jensen, T.

    1999-01-01

    A study has been completed to assess the capabilities of X-ray K-edge analysis in the measurement of RCRA metal contamination of sludge packaged in drums. Results were obtained for mercury and lead contamination. It was not possible to measure cadmium contamination using this technique. No false positive signals were observed. In cases where uniformity of the sludge can be assumed, this analysis can provide a quick, accurate measurement of heavy-metal contamination

  6. X-ray spectroscopy at the Mn K edge in LaMnO3 : An ab initio study

    NARCIS (Netherlands)

    Hozoi, L.; Vries, A.H. de; Broer, R.

    2001-01-01

    We present ab initio quantum chemical embedded cluster calculations of Mn core-valence and d-d transitions in LaMnO3. The results are also important for the analysis of recent x-ray absorption and x-ray scattering experiments at the Mn K edge in LaMnO3. We find that the first two peaks of the

  7. Operating software for plutonium measurements in the KfK K-edge densitometer. A user's guide

    International Nuclear Information System (INIS)

    Eberle, H.

    1983-09-01

    A set of computer programs has been developed for the execution of plutonium concentration measurements in the KfK K-edge photon absorptiometer for performance evaluation. The programs are implemented on a ND-6620 data acquisition and processing system. A short description of the programs and commands for data accumulation and analysis is given. Nevertheless, the user should be familiar with the ND-6620 data acquisition and processing system, its system software, and with the FORTRAN programming language. (orig./HP)

  8. Evaluation of the supraaortic arteries using non-contrast-enhanced Velocity MR Angiography ''Inhance''

    Energy Technology Data Exchange (ETDEWEB)

    Lummel, Nina; Lutz, Juergen; Linn, Jennifer [University of Munich (LMU), Department of Neuroradiology, Munich (Germany); Boeckh-Behrens, Tobias [Technical University Munich, Department of Neuroradiology, Munich (Germany); Burke, Michael [GE Healthcare, Solingen (Germany)

    2012-11-15

    The aim of this study was to compare the recently developed phase contrast-based Inhance 3D Velocity magnetic resonance angiography technique (Inhance) to the contrast-enhanced standard method (CE-MRA) in the evaluation of the supraaortic arteries. Inhance and CE-MRA were performed in ten consecutive patients with a suspected pathology of the supraaortic arteries on a 3-T MR scanner. Two neuroradiologists evaluated in consensus both sequences regarding the visualisation of the supraaortic arteries and their segments on a five-point score. Diagnostic certainty regarding the overall presence of a vascular pathology was rated on the same five-point score. On CE-MRA as well as on Inhance, a vascular pathology of the supraaortic arteries was detected in seven patients. There was no statistically significant difference in the overall diagnostic certainty regarding the presence or absence of pathologic findings for CE-MRA compared to Inhance. Furthermore, no statistically significant difference was found with regard to visualisation of the distal cervical and intracranial arterial segments, while CE-MRA was superior to Inhance in the visualisation of the origins of the cervical vessels from the aortic arch. Non-contrast Inhance proved useful in the evaluation of the supraaortic arteries with limited assessment of the proximal supraaortic branches. Hence, this technique features a valuable alternative to CE-MRA in the visualisation of the supraaortic arteries, particularly in patients with renal insufficiency. (orig.)

  9. Analysis of factors influencing the integrated bolus peak timing in contrast-enhanced brain computed tomographic angiography

    International Nuclear Information System (INIS)

    Son, Soon Yong; Choi, Kwan Woo; Jeong, Hoi Woun; Jang, Seo Goo; Jung, Jae Young; Yun, Jung Soo; Kim, Ki Won; Lee, Young Ah; Son, Jin Hyun; Min, Jung Whan

    2016-01-01

    The objective of this study was to analyze the factors influencing integrated bolus peak timing in contrast- enhanced computed tomographic angiography (CTA) and to determine a method of calculating personal peak time. The optimal time was calculated by performing multiple linear regression analysis, after finding the influence factors through correlation analysis between integrated peak time of contrast medium and personal measured value by monitoring CTA scans. The radiation exposure dose in CTA was 716.53 mGy·cm and the radiation exposure dose in monitoring scan was 15.52 mGy (2 - 34 mGy). The results were statistically significant (p < .01). Regression analysis revealed, a -0.160 times decrease with a one-step increase in heart rate in male, and -0.004, -0.174, and 0.006 times decrease with one-step in DBP, heart rate, and blood sugar, respectively, in female. In a consistency test of peak time by calculating measured peak time and peak time by using the regression equation, the consistency was determined to be very high for male and female. This study could prevent unnecessary dose exposure by encouraging in clinic calculation of personal integrated peak time of contrast medium prior to examination

  10. Comparison of acetazolamide-enhanced brain SPECT using Tc-99m ECD with cerebral angiography in patients with cerebrovascular disease

    International Nuclear Information System (INIS)

    Choi, Y. Y.; Moon, D. H.; Ryu, J. S.; Yang, S. H.; Lee, H. K.; Lee, J. H.; Kim, J. S.; Kim, K. A.

    1997-01-01

    Cerebral vascular reserve can be assessed by development of collateral channels (DCC) on cerebral angiography(CA) or vasoreactivity (VR) on acetazolamide-enhanced brain SPECT (ACZ-SPECT). The purpose of this study was to compare Tc-99m ECD ACZ-SPECT with CA in the evaluation of vascular reserve in patients (pts) with cerebrovascular disease(CVD). Twenty seven patients with CVD, including TIA (n=13), infarction (n=11) and asymptomatic pts (AS, n=3), underwent CA and ACZ-SPECT. Basal and ACZ-SPECT was obtained consecutively, and image subtraction was performed. On CA, degree of DCC was scored 0-3 (0: normal, 3: poor) according to parenchymal staining on delayed film. In ACZ-SPECT, decrease of VR was graded 0-3 (0: normal, 3: more than 30% decrease). The correlation between degree of stenosis, DCC and VR were analyzed. 1) Variable degree of VR or DCC was observed in totally occluded or stenotic cerebral arterial territories. 2) In arterial territories with poor DCC, ACZ-SPECT showed poor VR. However, in 5 out of 11 TIA or AS with good DCC, poor VR was observed. These data suggests that 1) cerebral hemodynamic status cannot be assessed by the degree of stenosis on CA alone. 2) DCC may overestimate the cerebral vascular reserve in patients with TIA or AS. 3) ACZ-SPECT plays a complementary role to CA for evaluation of cerebral hemodynamic status in pts with CVD

  11. Contrast-enhanced 3D MR angiography of the chest and abdomen with breath-holding using phase reordering

    International Nuclear Information System (INIS)

    Amanuma, Makoto; Sugimoto, Eiichi; Enomoto, Kyoko; Watabe, Tsuneya; Heshiki, Atsuko; Hirata, Hisashi; Kimura, Toshihiko; Takizawa, Osamu.

    1995-01-01

    This report presents the feasibility of phase-reordered contrast-enhanced three-dimensional MR angiography in 32 consecutive patients with vascular abnormalities in the chest and abdomen. To suppress motion artifacts due to respiratory corruption, a phase-reordering technique was introduced so that the low frequency components of the phase data were obtained first during the imaging period. Image quality and degree of motion suppression were assessed by four radiologists independently without information on breath-holding time. Abnormalities were detected in 30 cases (93.8%), and their extent was correctly assessed in 28 cases (87.5%). More confident assessment was possible in abnormalities of the pulmonary vessels and thoracic aorta than in those of the abdominal aorta and portal venous system. With phase reordering, more than 20 seconds of breath-holding ensured image quality sufficient to correctly assess the vascular abnormalities. While this technique is easy and requires only single breath-holding, it can provide excellent MRA without slice-to-slice spatial misregistration. (author)

  12. Contrast-enhanced three-dimensional MR angiography of neck vessels: does dephasing effect alter diagnostic accuracy?

    International Nuclear Information System (INIS)

    Cosottini, M.; Calabrese, R.; Murri, L.; Puglioli, M.; Zampa, V.; Michelassi, M.C.; Ortori, S.; Bartolozzi, C.

    2003-01-01

    The aim of this study was to evaluate diagnostic accuracy of contrast-enhanced MRA (CEMRA) compared with digital subtraction angiography (DSA) in studying neck vessels of 48 patients. In three groups of patients, we used three MRA protocols differing for voxel size to assess if intravoxel dephasing effects could modify accuracy of CEMRA. Accuracy and correlation with DSA results were calculated in all patients and separately in the three groups. A qualitative analysis of the likeness between morphology of the stenosis in CEMRA and DSA images was also assessed. In all patients accuracy and agreement with DSA were 96% and k=0.85 in subclavian arteries, 96% and k=0.84 in vertebral artery, 97% and k=0.88 in common carotid arteries, and 94% and k=0.86 in internal carotid arteries. In the three groups accuracy and agreement with DSA did not show any significant difference. Qualitative analysis of CEMRA and DSA images revealed a better agreement in depicting the morphology of stenosis using a smaller voxel size. The CEMRA represents a powerful tool for the non-invasive evaluation of neck vessels. Overestimation trend of CEMRA is confirmed and the reduction of voxel size, decreasing the dephasing intravoxel effect, allows to have a better overlapping of stenosis morphology on CEMRA compared with DSA, but it does not yield diagnostic gain in the stenosis grading. (orig.)

  13. Detection of hypoxic-ischemic brain injury with 3D-enhanced T2* weighted angiography (ESWAN) imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gang, QiangQiang, E-mail: rousikang@163.com; Zhang, Jianing, E-mail: 1325916060@qq.com; Hao, Peng, E-mail: 1043600590@qq.com; Xu, Yikai, E-mail: yikaivip@163.com

    2013-11-01

    Objective: To demonstrate the use of 3D-enhanced T2* weighted angiography (ESWAN) imaging for the observation and quantification of the evolution of brain injury induced by a recently developed model of hypoxic-ischemic brain injury (HI/R) in neonatal piglets. Methods: For these experiments, newborn piglets were subjected to HI/R injury, during which ESWAN scanning was performed, followed by H and E staining and immunohistochemistry of AQP-4 expression. Results: In the striatum, values from T2* weighted magnetic resonance imaging (MRI) increased and reached their highest level at 3 days post injury, whereas T2* values increased and peaked at 24 h in the subcortical region. The change in T2* values was concordant with brain edema. Phase values in the subcortical border region were not dependent on time post-injury. Magnitude values were significantly different from the control group, and increased gradually over time in the subcortical border region. Susceptibility-weighted images (SWI) indicated small petechial hemorrhages in the striatum and thalamus, as well as dilated intramedullary veins. Conclusion: SWI images can be used to detect white and gray matter microhemorrhages and dilated intramedullary veins. The T2*, phase, and magnitude map can also reflect the development of brain injury. Our data illustrate that ESWAN imaging can increase the diagnostic sensitivity and specificity of MRI in neonatal hypoxic-ischemic encephalopathy.

  14. Detection of hypoxic-ischemic brain injury with 3D-enhanced T2* weighted angiography (ESWAN) imaging

    International Nuclear Information System (INIS)

    Gang, QiangQiang; Zhang, Jianing; Hao, Peng; Xu, Yikai

    2013-01-01

    Objective: To demonstrate the use of 3D-enhanced T2* weighted angiography (ESWAN) imaging for the observation and quantification of the evolution of brain injury induced by a recently developed model of hypoxic-ischemic brain injury (HI/R) in neonatal piglets. Methods: For these experiments, newborn piglets were subjected to HI/R injury, during which ESWAN scanning was performed, followed by H and E staining and immunohistochemistry of AQP-4 expression. Results: In the striatum, values from T2* weighted magnetic resonance imaging (MRI) increased and reached their highest level at 3 days post injury, whereas T2* values increased and peaked at 24 h in the subcortical region. The change in T2* values was concordant with brain edema. Phase values in the subcortical border region were not dependent on time post-injury. Magnitude values were significantly different from the control group, and increased gradually over time in the subcortical border region. Susceptibility-weighted images (SWI) indicated small petechial hemorrhages in the striatum and thalamus, as well as dilated intramedullary veins. Conclusion: SWI images can be used to detect white and gray matter microhemorrhages and dilated intramedullary veins. The T2*, phase, and magnitude map can also reflect the development of brain injury. Our data illustrate that ESWAN imaging can increase the diagnostic sensitivity and specificity of MRI in neonatal hypoxic-ischemic encephalopathy

  15. Aortic Volumetry at Contrast-Enhanced Magnetic Resonance Angiography: Feasibility as a Sensitive Method for Monitoring Bicuspid Aortic Valve Aortopathy.

    Science.gov (United States)

    Trinh, Brian; Dubin, Iram; Rahman, Ozair; Ferreira Botelho, Marcos P; Naro, Nicholas; Carr, James C; Collins, Jeremy D; Barker, Alex J

    2017-04-01

    Bicuspid aortic valve patients can develop thoracic aortic aneurysms and therefore require serial imaging to monitor aortic growth. This study investigates the reliability of contrast-enhanced magnetic resonance angiography (CEMRA) volumetry compared with 2-dimensional diameter measurements to identify thoracic aortic aneurysm growth. A retrospective, institutional review board-approved, and Health Insurance Portability and Accountability Act-compliant study was conducted on 20 bicuspid aortic valve patients (45 ± 8.9 years, 20% women) who underwent serial CEMRA with a minimum imaging follow-up of 11 months. Magnetic resonance imaging was performed at 1.5 T with electrocardiogram-gated, time-resolved CEMRA. Independent observers measured the diameter at the sinuses of Valsalva (SOVs) and mid ascending aorta (MAA) as well as ascending aorta volume between the aortic valve annulus and innominate branch. Intraobserver/interobserver coefficient of variation (COV) and intraclass correlation coefficient (ICC) were computed to assess reliability. Growth rates were calculated and assessed by Student t test (P volumetry. Three-dimensional CEMRA volumetry exhibited a larger effect when examining percentage growth, a better ICC, and a marginally lower COV. Volumetry may be more sensitive to growth and possibly less affected by error than diameter measurements.

  16. MR angiography with Vasovist

    Energy Technology Data Exchange (ETDEWEB)

    Goyen, Mathias [University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20251 Hamburg (Germany)], E-mail: goyen@uke.uni-hamburg.de

    2007-12-15

    Vasovist (Gadofosveset) is the first intravascular contrast agent approved for use with magnetic resonance angiography in the European Union. This blood pool contrast agent reversibly binds to albumin providing extended intravascular enhancement compared to existing extracellular magnetic resonance contrast agents. Prior to approval, Vasovist underwent extensive clinical and pre-clinical testing to evaluate the safety and efficacy of the drug. The clinical trials program included blinded, placebo-controlled dose ranging, efficacy in a variety of vascular beds (aorto-iliac, renal, pedal), examination of potential drug interaction with warfarin, and comparison with X-ray angiography. The clinical trials show that Vasovist-enhanced MR angiography is safe and well tolerated in patients with vascular disease, effective for the detection of vascular stenosis and aneurysms, significantly more accurate (both more sensitive and specific) than non-contrast MR angiography for the diagnosis of vascular stenoses, and similar to conventional angiography for the overall characterization of vascular disease, without the need for catheterization. This review article highlights the product characteristics of Vasovist, gives an overview of the clinical development program and discusses selected clinical applications.

  17. MR angiography with Vasovist

    International Nuclear Information System (INIS)

    Goyen, Mathias

    2007-01-01

    Vasovist (Gadofosveset) is the first intravascular contrast agent approved for use with magnetic resonance angiography in the European Union. This blood pool contrast agent reversibly binds to albumin providing extended intravascular enhancement compared to existing extracellular magnetic resonance contrast agents. Prior to approval, Vasovist underwent extensive clinical and pre-clinical testing to evaluate the safety and efficacy of the drug. The clinical trials program included blinded, placebo-controlled dose ranging, efficacy in a variety of vascular beds (aorto-iliac, renal, pedal), examination of potential drug interaction with warfarin, and comparison with X-ray angiography. The clinical trials show that Vasovist-enhanced MR angiography is safe and well tolerated in patients with vascular disease, effective for the detection of vascular stenosis and aneurysms, significantly more accurate (both more sensitive and specific) than non-contrast MR angiography for the diagnosis of vascular stenoses, and similar to conventional angiography for the overall characterization of vascular disease, without the need for catheterization. This review article highlights the product characteristics of Vasovist, gives an overview of the clinical development program and discusses selected clinical applications

  18. Catheter Angiography

    Medline Plus

    Full Text Available ... to your primary care or referring physician , who will discuss the results with you. top of page What are the benefits vs. risks? Benefits Angiography may eliminate the need ...

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    Full Text Available ... diagnosis and treatment in a single procedure. An example is finding an area of severe arterial narrowing, ... contrast material, your radiologist may advise that you take special medication for 24 hours before catheter angiography ...

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    Full Text Available ... imaging (MRI) In catheter angiography, a thin plastic tube, called a catheter , is inserted into an artery ... examined, a contrast material is injected through the tube and images are captured using a small dose ...

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  4. Catheter Angiography

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  8. Prominent porto-systemic collateral pathways in patients with portal hypertension: demonstration by gadolinium-enhanced magnetic resonance angiography; Vias colaterais porto-sistemicas exuberantes em portadores de hipertensao portal: demonstracao pela angiografia por ressonancia magnetica com gadolinio

    Energy Technology Data Exchange (ETDEWEB)

    Caldana, Rogerio Pedreschi; Bezerra, Alexandre Araujo Sergio; Cecin, Alexnadre Oliveira; Souza, Luis Ronan Marques Ferreira de; Goldman, Susan Menasce; D' Ippolito, Giuseppe; Szejnfeld, Jacob [Universidade Federal de Sao Paulo (UNIFESP/EPM), Sao Paulo, SP (Brazil). Dept. de Diagnostico por Imagem]. E-mail: rogercal@uol.com.br

    2003-03-01

    To demonstrate the usefulness of gadolinium-enhanced magnetic resonance angiography in the evaluation of prominent porto-systemic collateral pathways. We reviewed the images from 40 patients with portal hypertension studied with gadolinium-enhanced magnetic resonance angiography and selected illustrative cases of prominent porto-systemic collateral pathways. The scans were performed using high field equipment (1.5 Tesla) and a 3 D volume technique. Image were obtained after intravenous injection of paramagnetic contrast media using a power injector. Magnetic resonance angiography demonstrated with precision the porto-systemic collateral pathways, particularly when investigating extensive territories or large vessels. The cases presented show the potential of this method in the investigation of patients with portal hypertension. Gadolinium-enhanced magnetic resonance angiography is a useful method for the evaluation of patients with portal hypertension and prominent collateral pathways. (author)

  9. Contrast-enhanced three-dimensional fast-spoiled gradient magnetic resonance angiography of the renal arteries for potential living renal transplant donors: a comparative study with digital subtraction angiography

    International Nuclear Information System (INIS)

    Al-Saeed, O.; Sheikh, M.; Al-Khawari, H.; Ismail, M.; Al-Moosawi, M.

    2005-01-01

    Preoperative assessment of the arterial anatomy of prospective renal donors is essential. Various non-invasive techniques are used for such evaluation. We conducted this study using contrast-enhanced 3-D fast-spoiled gradient (CE 3-D FSPGR) magnetic resonance angiography (MRA) on a 1.0 Tesla magnet, for preoperative definition of the renal arteries. Forty-five preoperative living renal donors underwent CE 3-D FSPGR MRA of the renal vessels and the results were compared with conventional digital subtraction angiography (DSA). The renal vascular anatomy, both normal and with variations, was satisfactorily defined in all 45 cases with CE 3-D FSPGR MRA. Fifteen cases showed an accessory or aberrant arterial supply. A small aneurysm was shown in one case. All cases compared well with conventional DSA. Our study revealed that CE 3-D FSPGR MRA on a lower field strength magnet is accurate in defining the renal vascular anatomy and its variations. Copyright (2005) Blackwell Science Pty Ltd

  10. Diagnosis of occlusive arterial disease and assessment of IVR with fat-suppressed gadolinium-enhanced three-dimensional MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Yasuo; Gemma, Kazuhito; Kawamata, Hiroshi; Okajima, Yuhji; Watari, Jun; Kumazaki, Tatsuo [Nippon Medical School, Tokyo (Japan); Maki, Toshio; Tsuchihashi, Toshio

    1996-10-01

    Fat-suppressed gadolinium-enhanced three-dimensional MR angiography (FS-CE-3D-MRA) was performed to make a diagnosis of occlusive arterial disease and evaluate the effectiveness of IVR treatment for it. FS-CE-3D-MRA delineated stenosis of common iliac arteries, which was confirmed by X-ray angiography. FS-CE-3D-MRA also detected ulcerated plaque and arterial wall irregularity. The effectiveness of IVR as atherectomy and stent placement was accurately assessed with FS-CE-3D-MRA. FS-CE-3D-MRA was useful in evaluating occlusive arterial disease with short examination times and high spatial resolution, although iliac circumflexial arteries were not detected by this technique. (author)

  11. Investigation of the saturation pulse artifact in non-enhanced MR angiography of the lower extremity arteries at 7 Tesla.

    Directory of Open Access Journals (Sweden)

    Sören Johst

    Full Text Available When performing non-enhanced time-of-flight MR angiography of the lower extremity arteries at 7 T with cardiac triggering, the acquisition time is a crucial consideration. Therefore, in previous studies, saturation RF pulses were applied only every second TR. In the axial source images a slight artifact with an appearance similar to aliasing could be observed. The purpose of this study was to investigate the origin of this artifact. The reason for the artifact is supposed to be related to the two effective TRs during acquisition caused by the sparsely applied saturation RF pulse. Several sequence variants were simulated and implemented within the sequence source code to examine this hypothesis. An adaptation of the excitation flip angles for each TR as well as a correction factor for the k-space data was calculated. Additionally, a different ordering of the k-space data during acquisition was implemented as well as the combination of the latter with the k-space correction factor. The observations from the simulations were verified using both a static and a flow phantom and, finally, in a healthy volunteer using the same measurement setup as in previous volunteer and patient studies. Of all implemented techniques, only the reordering of the k-space was capable of suppressing the artifact almost completely at the cost of creating a ringing artifact. The phantom measurements showed the same results as the simulations and could thus confirm the hypothesis regarding the origin of the artifact. This was additionally verified in the healthy volunteer. The origin of the artifact could be confirmed to be the periodic signal variation caused by two effective TRs during acquisition.

  12. Investigation of the saturation pulse artifact in non-enhanced MR angiography of the lower extremity arteries at 7 Tesla.

    Science.gov (United States)

    Johst, Sören; Maderwald, Stefan; Fischer, Anja; Quick, Harald H; Ladd, Mark E; Orzada, Stephan

    2015-01-01

    When performing non-enhanced time-of-flight MR angiography of the lower extremity arteries at 7 T with cardiac triggering, the acquisition time is a crucial consideration. Therefore, in previous studies, saturation RF pulses were applied only every second TR. In the axial source images a slight artifact with an appearance similar to aliasing could be observed. The purpose of this study was to investigate the origin of this artifact. The reason for the artifact is supposed to be related to the two effective TRs during acquisition caused by the sparsely applied saturation RF pulse. Several sequence variants were simulated and implemented within the sequence source code to examine this hypothesis. An adaptation of the excitation flip angles for each TR as well as a correction factor for the k-space data was calculated. Additionally, a different ordering of the k-space data during acquisition was implemented as well as the combination of the latter with the k-space correction factor. The observations from the simulations were verified using both a static and a flow phantom and, finally, in a healthy volunteer using the same measurement setup as in previous volunteer and patient studies. Of all implemented techniques, only the reordering of the k-space was capable of suppressing the artifact almost completely at the cost of creating a ringing artifact. The phantom measurements showed the same results as the simulations and could thus confirm the hypothesis regarding the origin of the artifact. This was additionally verified in the healthy volunteer. The origin of the artifact could be confirmed to be the periodic signal variation caused by two effective TRs during acquisition.

  13. Automatic assessment of coronary artery calcium score from contrast-enhanced 256-row coronary computed tomography angiography.

    Science.gov (United States)

    Rubinshtein, Ronen; Halon, David A; Gaspar, Tamar; Lewis, Basil S; Peled, Nathan

    2014-01-01

    The coronary artery calcium score (CS), an independent predictor of cardiovascular events, can be obtained from a stand-alone nonenhanced computed tomography (CT) scan (CSCT) or as an additional nonenhanced procedure before contrast-enhanced coronary CT angiography (CCTA). We evaluated the accuracy of a novel fully automatic tool for computing CS from the CCTA examination. One hundred thirty-six consecutive symptomatic patients (aged 59 ± 11 years, 40% female) without known coronary artery disease who underwent both 256-row CSCT and CCTA were studied. Original scan reconstruction (slice thickness) was maintained (3 mm for CSCT and 0.67 mm for CCTA). CS was computed from CCTA by an automatic tool (COR Analyzer, rcadia Medical Imaging, Haifa, Israel) and compared with CS results obtained by standard assessment of nonenhanced CSCT (HeartBeat CS, Philips, Cleveland, Ohio). We also compared both methods for classification into 5 commonly used CS categories (0, 1 to 10, 11 to 100, 101 to 400, >400 Agatston units). All scans were of diagnostic quality. CS obtained by the COR Analyzer from CCTA classified 111 of 136 (82%) of patients into identical categories as CS by CSCT and 24 of remaining 25 into an adjacent category. Overall, CS values from CCTA showed high correlation with CS values from CSCT (Spearman rank correlation = 0.95, p automatically computed from 256-row CCTA correlated highly with standard CS values obtained from nonenhanced CSCT. CS obtained directly from CCTA may obviate the need for an additional scan and attendant radiation. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Gadopentate dimeglumine enhanced MR angiography (MRA) for staging AAA: a correlation with DSA and CT

    International Nuclear Information System (INIS)

    Arlart, I.P.; Gerlach, A.; Kolb, M.; Erpenbach, S.; Wuerstlin, S.

    1997-01-01

    Purpose: To evaluate a contrast-enhanced (CE) MRA sequence for staging AAA. Methods: In 24 patients (male=20, female=4, age=44-81 y) with known AAA the abdominal aorta and its branches including the iliac arteries were imaged, using a 3D GRE-FISP sequence (1.5 T, T R /T E /FA=25/6/35, slab=100-140 mm, 32 part., FOV=440-450 mm, matrix=256x256) during an i.v. infusion of 40 ml of gadopentate dimeglumine. In addition, representative axial single slices (2D breathhold FLASH-sequence: T R /T E /FA=82/5/30) were acquired following contrast application. MR-results were correlated with i.a. DSA and CT studies. Results: With CE-MRA, AAA (n=24) and iliac aneurysms (n=17) could be evaluated in all cases (sens.=100%, spec.=100%) including luminal patency and mural thrombus. 50/54 renal arteries could be identified, 4/6 accessory renal arteries (sens=66,6%, spec.=100%), 8/9 renal artery stenoses>50% (sens.=88.8%, spec.=89.3%), 1/1 renal artery occlusion and 7/8 iliac artery stenoses>50% (sens.=87.5%, spec.=97.5%) were depicted correctly. Proximal portion of sup. mes. art. could be detected and evaluated in 21/24 cases. Quantitative determination of therapeutically relevant vascular paramters using MRA was comparable to DSA and CT. (orig./AJ) [de

  15. Intraindividual assessment of the thoracic aorta using contrast and non-contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Tengg-Kobligk, Hendrik von; Gruenberg, K.M.; Giesel, F.L.; Ley-Zaporozhan, J.; Ley, S.; Henninger, V.; Kauczor, H.U.; Radiologische Universitaetsklinik Heidelberg; Boeckler, D.; Krummenauer, F.

    2009-01-01

    To avoid intravenous contrast media application, new MRA sequences using inherent blood contrast are available. The clinical use of these non-contrast-enhanced MRA (non-CE-MRA) sequences is still limited for the aorta. Thus, the goal was to compare a standard CE-MRA with a non-CE-MRA for the thoracic aorta. Ethics committee approval and informed consent were obtained. CE-MRA and non-CE-MRA (1.5T) were performed in the same 50 healthy volunteers (mean age: 48). CE-MRA: GRE-Turbo-Flash-3D (1.2 x 1.2 x 1.6 mm 3 ), 0.15 mmol Gd/kg, TA 22 ± 2sec. Non-CE-MRA: Respiratory-and cardiac-gated, T 2-prepared 3D-trueFISP (1.2 x 1.2 x 1.3 mm 3 ), TA 14 ± 5 min. Assessment included (3 readers, consensus): image quality (sharpness of vessel wall, signal homogeneity, artifacts) at the ascending aorta, arch, descending aorta and supra-aortic vessels. The image quality in the ascending aorta was rated 'excellent' in 78 %, 'moderate' in 22 %, 'poor' in 0 % for non-CE-MRA versus 22 %, 50 %, and 28 % for CE-MRA (Cohen's kappa = 29 %, McNemar p < 0.001). In a comparison of non-CE-MRA versus CE-MRA, the aortic arch and descending aorta showed no significant difference (kappa = 58 %/p = 0.250 and kappa = 100 %/p 1.000, respectively). Supra-aortic vessels were rated 'excellent' 45 %/49 %, 'moderate' 30 %/49 % and 'poor' 13 %/2 %, 12 % of supra-aortic vessels were visualized < 1 cm at non-CE-MRA. (orig.)

  16. Interpolation of Gamma-ray buildup Factors for Arbitrary Source Energies in the Vicinity of the K-edge

    International Nuclear Information System (INIS)

    Michieli, I.

    1998-01-01

    Recently, a new buildup factors approximation formula based on the expanded polynomial set (E-P function) was successfully introduced (Michieli 1994.) with the maximum approximation error below 4% throughout the standard data domain. Buildup factors interpolation in E-P function parameters for arbitrary source energies, near the K-edge in lead, was satisfactory. Maximum interpolation error, for lead, lays within 12% what appears to be acceptable for most Point Kernel application. 1991. Harima at. al., showed that, near the K-edge, fluctuation in energy of exposure rate attenuation factors i.e.: D(E)B(E, μ E r)exp(-μ E r), given as a function of penetration depth (r) in ordinary length units (not mfps.), is not nearly as great as that of buildup factors. That phenomenon leads to the recommendation (ANSI/ANS-6.4.3) that interpolations in that energy range should be made in the attenuation factors B(E, μ E r)exp(-μ E r) rather than in the buildup factors alone. In present article, such interpolation approach is investigated by applying it to the attenuation factors in lead, with E-P function representation of exposure buildup factors. Simple form of the E-P function leads to strait calculation of new function parameters for arbitrary source energy near the K-edge and thus allowing the same representation form of buildup factors as in the standard interpolation procedure. results of the interpolation are discussed and compared with those from standard approach. (author)

  17. Adsorption behavior of sulfur-containing amino acid molecule on transition metal surface studied by S K-edge NEXAFS

    International Nuclear Information System (INIS)

    Yagi, S.; Matsumura, K.; Nakano, Y.; Ikenaga, E.; Sardar, S.A.; Syed, J.A.; Soda, K.; Hashimoto, E.; Tanaka, K.; Taniguchi, M.

    2003-01-01

    Adsorption behavior of a sulfur-containing amino acid L-cysteine molecule on transition metal surface have been investigated by S K-edge near-edge X-ray absorption fine structure. The L-cysteine molecule for first adsorption layer was found to dissociate on polycrystalline nickel surface, whereas molecularly adsorbed on copper surface at room temperature. Most of the L-cysteine molecules have been dissociated on nickel surface in annealing condition up to 353 K. On the other hand, the L-cysteine molecule did not dissociate on copper surface and the elongation of the S-C bonding occurred at 353 K

  18. In situ Ru K-edge EXAFS of CO adsorption on a Ru modified Pt/C fuel cell catalyst

    International Nuclear Information System (INIS)

    Rose, Abigail; Bilsborrow, Robert; King, Colin R.; Ravikumar, M.K.; Qian Yangdong; Wiltshire, Richard J.K.; Crabb, Eleanor M.; Russell, Andrea E.

    2009-01-01

    The Ru-CO bond of CO adsorbed on a Ru modified Pt/C fuel cell catalyst has been directly probed by in situ EXAFS at the Ru K-edge, providing evidence of a CO:metal surface atom ratio greater than 1:1 and that CO is adsorbed at bridging sites associated with Ru atoms at the surface of the catalyst nanoparticles. This result illustrates the limitations of single crystal models as representations of the bonding of adsorbed species at nanoparticle surfaces.

  19. Pressure-induced magnetic transition in Fe sub 4 N probed by Fe K-edge XMCD measurement

    CERN Document Server

    Ishimatsu, N; Maruyama, H; Kawamura, N; Suzuki, M; Ohishi, Y; Ito, M; Nasu, S; Kawakami, T

    2003-01-01

    X-ray magnetic circular dichroism (XMCD) of gamma'-iron nitride (Fe sub 4 N) was recorded at Fe K-edge under high pressure up to 27 GPa. The XMCD intensity decreased remarkably with pressure, and vanished at 24 GPa. Compressibility was measured by the X-ray diffraction method. These results indicate that Fe sub 4 N undergoes a second-order phase transition from the ferromagnetic state to a paramagnetic state without any structural change. The pressure-induced demagnetizing process is discussed in terms of the Fe magnetic states in the local environment.

  20. Sulfur K-edge X-ray absorption spectroscopy and time-dependent density functional theory of arsenic dithiocarbamates.

    Science.gov (United States)

    Donahue, Courtney M; Pacheco, Juan S Lezama; Keith, Jason M; Daly, Scott R

    2014-06-28

    S K-edge X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TDDFT) calculations were performed on a series of As[S2CNR2]3 complexes, where R2 = Et2, (CH2)5 and Ph2, to determine how dithiocarbamate substituents attached to N affect As[S2CNR2]3 electronic structure. Complimentary [PPh4][S2CNR2] salts were also studied to compare dithiocarbamate bonding in the absence of As. The XAS results indicate that changing the orientation of the alkyl substituents from trans to cis (R2 = Et2vs. (CH2)5) yields subtle variations whereas differences associated with a change from alkyl to aryl are much more pronounced. For example, despite the differences in As 4p mixing, the first features in the S K-edge XAS spectra of [PPh4][S2CNPh2] and As[S2CNPh2]3 were both shifted by 0.3 eV compared to their alkyl-substituted derivatives. DFT calculations revealed that the unique shift observed for [PPh4][S2CNPh2] is due to phenyl-induced splitting of the π* orbitals delocalized over N, C and S. A similar phenomenon accounts for the shift observed for As[S2CNPh2]3, but the presence of two unique S environments (As-S and As···S) prevented reliable analysis of As-S covalency from the XAS data. In the absence of experimental values, DFT calculations revealed a decrease in As-S orbital mixing in As[S2CNPh2]3 that stems from a redistribution of electron density to S atoms participating in weaker As···S interactions. Simulated spectra obtained from TDDFT calculations reproduce the experimental differences in the S K-edge XAS data, which suggests that the theory is accurately modeling the experimental differences in As-S orbital mixing. The results highlight how S K-edge XAS and DFT can be used cooperatively to understand the electronic structure of low symmetry coordination complexes containing S atoms in different chemical environments.

  1. Multiple Scattering Approach to Polarization Dependence of F K-Edge XANES Spectra for Highly Oriented Polytetrafluoroethylene (PTFE) Thin Film

    International Nuclear Information System (INIS)

    Nagamatsu, S.; Ono, M.; Kera, S.; Okudaira, K. K.; Fujikawa, T.; Ueno, N.

    2007-01-01

    The polarization dependence of F K-edge X-ray absorption near edge structure (XANES) spectra of highly-oriented thin-film of polytetrafluoroethylene (PTFE) has been analyzed by using multiple scattering theory. The spectra show clear polarization dependence due to the highly-oriented structure. The multiple scattering calculations reflects a local structure around an absorbing atom. The calculated results obtained by considering intermolecular-interactions are in good agreement with the observed polarization-dependence. We have also analyzed structural models of the radiation damaged PTFE films

  2. Bimagnon studies in cuprates with resonant inelastic x-ray scattering at the O K edge. I. Assessment on La2CuO4 and comparison with the excitation at Cu L3 and Cu K edges

    Science.gov (United States)

    Bisogni, V.; Simonelli, L.; Ament, L. J. P.; Forte, F.; Moretti Sala, M.; Minola, M.; Huotari, S.; van den Brink, J.; Ghiringhelli, G.; Brookes, N. B.; Braicovich, L.

    2012-06-01

    We assess the capabilities of magnetic resonant inelastic x-ray scattering (RIXS) at the O K edge in undoped cuprates by taking La2CuO4 as a benchmark case, based on a series of RIXS measurements that we present here. By combining the experimental results with basic theory we point out the fingerprints of bimagnon excitation in the O K edge RIXS spectra. These are a dominant peak around 450 meV, the almost complete absence of dispersion both with π and σ polarization, and the almost constant intensity vs the transferred momentum with σ polarization. This behavior is quite different from Cu L3 edge RIXS giving a strongly dispersing bimagnon tending to zero at the center of the Brillouin zone. This is clearly shown by RIXS measurements at the Cu L3 edge that we present. The Cu L3 bimagnon spectra and those at the Cu K edge—both from the literature and from our data—however, have the same shape. These similarities and differences are understood in terms of different sampling of the bimagnon continuum. This panorama points out the unique possibilities offered by O K RIXS in the study of magnetic excitations in cuprates near the center of the BZ.

  3. Feasibility of photon-counting K-edge imaging in X-ray and computed tomographic systems: Monte Carlo simulation studies

    International Nuclear Information System (INIS)

    Lee, Seung-Wan; Choi, Yu-Na; Cho, Hyo-Min; Lee, Young-Jin; Ryu, Hyun-Ju; Kim, Hee-Joung

    2011-01-01

    Conventional X-ray systems and X-ray computed tomography (CT) systems, which use detectors operated in the integrating mode, are not able to reflect spectral information because the detector output is proportional to the energy fluence integrated over the whole spectrum. Photon-counting detectors have been considered as alternative devices. These detectors can measure the photon energy deposited by each event and improve the image quality. In this study, we investigated the feasibility of K-edge imaging using a photon-counting detector and evaluated the capability of material decomposition in X-ray images. The geometries of X-ray imaging systems equipped with cadmium telluride (CdTe) detectors and phantoms consisting of different materials were designed using Geant4 Application for Tomographic Emission (GATE) version 6.0. To observe the effect of a discontinuity in the attenuation due to the K-edge of a high atomic number material, we chose the energy windows to be one below and one above the K-edge absorption energy of the target material. The contrast-to-noise ratios (CNRs) of the target materials were increased at selective energy levels above the K-edge absorption energy because the attenuation is more dramatically increased at energies above the K-edge absorption energy of the material than at energies below that. The CNRs for the target materials in the K-edge image were proportional to the material concentration. The results of this study show that K-edge imaging can be carried out in conventional X-ray systems and X-ray CT systems using CdTe photon-counting detectors and that the target materials can be separated from background materials by using K-edge imaging. The photon-counting detector has potential to provide improved image quality, and this study will be used as a basis for future studies on photon-counting X-ray imaging.

  4. Novel digital K-edge imaging system with transition radiation from an 855-MeV electron beam

    CERN Document Server

    Hagenbuck, F; Clawiter, N; Euteneuer, H; Görgen, F; Holl, P; Johann, K; Kiser, K H; Kemmer, J; Kerschner, T; Kettig, O; Koch, H; Kube, G; Lauth, W; Mauhay, H; Schütrumpf, M; Stotter, R; Strüder, L; Walcher, T; Wilms, A; von Zanthier, C; Zemter, M

    2001-01-01

    A novel K-edge imaging method has been developed at the Mainz Microtron MAMI aiming at a very efficient use of the transition radiation (TR) flux generated by the external 855-MeV electron beam in a foil stack. A fan-like quasi-monochromatic hard X-ray beam is produced from the +or-1-mrad-wide TR cone with a highly oriented pyrolytic graphite (HOPG) crystal. The absorption of the object in front of a 30 mm*10 mm pn charge-coupled device (pn-CCD) photon detector is measured at every pixel by a broad-band energy scan around the K-absorption edge. This is accomplished by a synchronous variation of the lateral crystal position and the electron beam direction which defines also the direction of the TR cone. The system has been checked with a phantom consisting of a 2.5- mu m thick molybdenum sample embedded in a 136- or 272- mu m-thick copper bulk foil. A numerical analysis of the energy spectrum for every pixel demonstrates that data as far as +or-0.75 keV away from the K edge of molybdenum at 20 keV still improv...

  5. Comparison of contrast enhanced MR-angiography-MRI and digital subtraction angiography in the evaluation of pancreas and/or kidney transplantation patients : initial experience

    NARCIS (Netherlands)

    Boeve, WJ; Kok, T; Tegzess, Adam; van Son, WJ; Ploeg, RJ; Sluiter, WJ; Kamman, RL

    To evaluate whether combined contrast enhanced MRA and MRI (ce-MRA-MRI) has the potential to replace intra-arterial DSA (i.a.DSA) in patients with impaired graft function or suspected of vascular complications after pancreas and/or kidney transplantation. 7 patients after combined pancreas-kidney

  6. Catheter Angiography

    Medline Plus

    Full Text Available ... rare, and radiology departments are well-equipped to deal with them. There is a small risk that ... standard x-ray contrast. Catheter angiography should be done very cautiously—if at all—in patients who ...

  7. Catheter Angiography

    Medline Plus

    Full Text Available ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different ... about radiology? Share your patient story here Images × ... Related Articles and Media Angioplasty and Vascular Stenting MR Angiography (MRA) Contrast ...

  8. Catheter Angiography

    Medline Plus

    Full Text Available ... navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us ... the equipment look like? How does the procedure work? How is the ... and treat medical conditions. Angiography uses one of three imaging technologies and, ...

  9. Prevalence Study of Proximal Vertebral Artery Stenosis Using High-Resolution Contrast-Enhanced Magnetic Resonance Angiography

    International Nuclear Information System (INIS)

    Kim, S.H.; Lee, J.S.; Kwon, O.K.; Han, M.K.; Kim, J.H.

    2005-01-01

    Purpose: To evaluate the prevalence of proximal vertebral artery stenosis, compared with those of the distal vertebral/basilar artery and extracranial internal carotid artery, in a large population of stroke and non-stroke patients. Material and Methods: Nine-hundred-and-thirty-five patients who underwent high-resolution contrast-enhanced magnetic resonance angiography in a regional general hospital were categorized into six groups based on neurological symptoms and disease: an asymptomatic group (n ∼ 182), a minor symptom group with headache or dizziness (n ∼ 519), a cardiac group with coronary artery steno-occlusive disease (n ∼ 15), a hemorrhagic group with old cerebral hemorrhage (n ∼ 26), an anterior circulation infarct group (n ∼ 121), and posterior circulation infarct group (n ∼ 72). Prevalence of stenosis of the proximal vertebral artery, distal vertebral/basilar artery, and internal carotid artery was analyzed. Results: The prevalence of stenosis of the proximal vertebral artery, distal vertebral/basilar artery, and internal carotid artery was 12.9%, 5.5%, and 7.2%, respectively, in the study population, and rose as the age increased (P <0.0001 for all arteries). The prevalence of stenosis of the proximal vertebral artery, distal vertebral/basilar artery, and internal carotid artery was 3.3%, 0.5%, and.1%, respectively, in the asymptomatic group; 8.3%, 2.1%, and 3.7%, respectively, in the minor symptom group; 13.3%, 6.7%, and 6.7%, respectively, in the cardiac group; 19.2%, 7.7%, and 7.7%, respectively, in the hemorrhagic group; 27.3%, 8.3%, and 25.6%, respectively, in the anterior circulation infarct group; and 44.4%, 36.1%, and 16.7%, respectively, in the posterior circulation infarct group. This increasing tendency of stenosis accordingly was statistically significant ( P <0.0001 for all arteries). Conclusion: The prevalence of proximal vertebral artery stenosis was highest, compared with those of the distal vertebral/basilar artery and

  10. Carbon K-edge X-ray absorption spectroscopy and time-dependent density functional theory examination of metal-carbon bonding in metallocene dichlorides.

    Science.gov (United States)

    Minasian, Stefan G; Keith, Jason M; Batista, Enrique R; Boland, Kevin S; Kozimor, Stosh A; Martin, Richard L; Shuh, David K; Tyliszczak, Tolek; Vernon, Louis J

    2013-10-02

    Metal-carbon covalence in (C5H5)2MCl2 (M = Ti, Zr, Hf) has been evaluated using carbon K-edge X-ray absorption spectroscopy (XAS) as well as ground-state and time-dependent hybrid density functional theory (DFT and TDDFT). Differences in orbital mixing were determined experimentally using transmission XAS of thin crystalline material with a scanning transmission X-ray microscope (STXM). Moving down the periodic table (Ti to Hf) has a marked effect on the experimental transition intensities associated with the low-lying antibonding 1a1* and 1b2* orbitals. The peak intensities, which are directly related to the M-(C5H5) orbital mixing coefficients, increase from 0.08(1) and 0.26(3) for (C5H5)2TiCl2 to 0.31(3) and 0.75(8) for (C5H5)2ZrCl2, and finally to 0.54(5) and 0.83(8) for (C5H5)2HfCl2. The experimental trend toward increased peak intensity for transitions associated with 1a1* and 1b2* orbitals agrees with the calculated TDDFT oscillator strengths [0.10 and 0.21, (C5H5)2TiCl2; 0.21 and 0.73, (C5H5)2ZrCl2; 0.35 and 0.69, (C5H5)2HfCl2] and with the amount of C 2p character obtained from the Mulliken populations for the antibonding 1a1* and 1b2* orbitals [8.2 and 23.4%, (C5H5)2TiCl2; 15.3 and 39.7%, (C5H5)2ZrCl2; 20.1 and 50.9%, (C5H5)2HfCl2]. The excellent agreement between experiment, theory, and recent Cl K-edge XAS and DFT measurements shows that C 2p orbital mixing is enhanced for the diffuse Hf (5d) and Zr (4d) atomic orbitals in relation to the more localized Ti (3d) orbitals. These results provide insight into how changes in M-Cl orbital mixing within the metallocene wedge are correlated with periodic trends in covalent bonding between the metal and the cyclopentadienide ancillary ligands.

  11. Non-contrast-enhanced 4D MR angiography with STAR spin labeling and variable flip angle sampling: a feasibility study for the assessment of Dural Arteriovenous Fistula

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jinhee; Kim, Bom-yi; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin; Kim, Bum-soo [The Catholic University of Korea, Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, Seoul (Korea, Republic of); Schmitt, Peter [Siemens AG, Healthcare Sector, Erlangen (Germany); Kim, Inseong; Paek, Munyoung [Siemens AG, Healthcare, Seoul (Korea, Republic of)

    2014-04-15

    This study aimed to evaluate the feasibility of non-contrast-enhanced 4D magnetic resonance angiography (NCE 4D MRA) with signal targeting with alternative radiofrequency (STAR) spin labeling and variable flip angle (VFA) sampling in the assessment of dural arteriovenous fistula (DAVF) in the transverse sinus. Nine patients underwent NCE 4D MRA for the evaluation of DAVF in the transverse sinus at 3 T. One patient was examined twice, once before and once after the interventional treatment. All patients also underwent digital subtraction angiography (DSA) and/or contrast-enhanced magnetic resonance angiography (CEMRA). For the acquisition of NCE 4D MRA, a STAR spin tagging method was used, and a VFA sampling was applied in the data readout module instead of a constant flip angle. Two readers evaluated the NCE 4D MRA data for the diagnosis of DAVF and its type with consensus. The results were compared with those from DSA and/or CEMRA. All patients underwent NCE 4D MRA without any difficulty. Among seven patients with patent DAVFs, all cases showed an early visualization of the transverse sinus on NCE 4D MRA. Except for one case, the type of DAVF of NCE 4D MRA was agreed with that of reference standard study. Cortical venous reflux (CVR) was demonstrated in two cases out of three patients with CVR. NCE 4D MRA with STAR tagging and VFA sampling is technically and clinically feasible and represents a promising technique for assessment of DAVF in the transverse sinus. Further technical developments should aim at improvements of spatial and temporal coverage. (orig.)

  12. Non-contrast-enhanced 4D MR angiography with STAR spin labeling and variable flip angle sampling: a feasibility study for the assessment of Dural Arteriovenous Fistula

    International Nuclear Information System (INIS)

    Jang, Jinhee; Kim, Bom-yi; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin; Kim, Bum-soo; Schmitt, Peter; Kim, Inseong; Paek, Munyoung

    2014-01-01

    This study aimed to evaluate the feasibility of non-contrast-enhanced 4D magnetic resonance angiography (NCE 4D MRA) with signal targeting with alternative radiofrequency (STAR) spin labeling and variable flip angle (VFA) sampling in the assessment of dural arteriovenous fistula (DAVF) in the transverse sinus. Nine patients underwent NCE 4D MRA for the evaluation of DAVF in the transverse sinus at 3 T. One patient was examined twice, once before and once after the interventional treatment. All patients also underwent digital subtraction angiography (DSA) and/or contrast-enhanced magnetic resonance angiography (CEMRA). For the acquisition of NCE 4D MRA, a STAR spin tagging method was used, and a VFA sampling was applied in the data readout module instead of a constant flip angle. Two readers evaluated the NCE 4D MRA data for the diagnosis of DAVF and its type with consensus. The results were compared with those from DSA and/or CEMRA. All patients underwent NCE 4D MRA without any difficulty. Among seven patients with patent DAVFs, all cases showed an early visualization of the transverse sinus on NCE 4D MRA. Except for one case, the type of DAVF of NCE 4D MRA was agreed with that of reference standard study. Cortical venous reflux (CVR) was demonstrated in two cases out of three patients with CVR. NCE 4D MRA with STAR tagging and VFA sampling is technically and clinically feasible and represents a promising technique for assessment of DAVF in the transverse sinus. Further technical developments should aim at improvements of spatial and temporal coverage. (orig.)

  13. Contrast-enhanced magnetic resonance angiography: first-pass arterial enhancement as a function of gadolinium-chelate concentration, and the saline chaser volume and injection rate.

    Science.gov (United States)

    Husarik, Daniela B; Bashir, Mustafa R; Weber, Paul W; Nichols, Eli B; Howle, Laurens E; Merkle, Elmar M; Nelson, Rendon C

    2012-02-01

    To evaluate the effect of the contrast medium (CM) concentration and the saline chaser volume and injection rate on first-pass aortic enhancement characteristics in contrast-enhanced magnetic resonance angiography using a physiologic flow phantom. Imaging was performed on a 3.0-T magnetic resonance system (MAGNETOM Trio, Siemens Healthcare Solutions, Inc, Erlangen, Germany) using a 2-dimensional fast low angle shot T1-weighted sequence (repetition time, 500 milliseconds; echo time, 1.23 milliseconds; flip angle, 8 degrees; 1 frame/s × 60 seconds). The following CM concentrations injected at 2 mL/s were used with 3 different contrast agents (gadolinium [Gd]-BOPTA, Gd-HP-DO3A, Gd-DTPA): 20 mL of undiluted CM (100%) and 80%, 40%, 20%, 10%, 5%, and 2.5% of the full amount, all diluted in saline to a volume of 20 mL to ensure equal bolus volume. The CM was followed by saline chasers of 20 to 60 mL injected at 2 mL/s and 6 mL/s. Aortic signal intensity (SI) was measured, and normalized SI versus time (SI/Tn) curves were generated. The maximal SI (SI(max)), bolus length, and areas under the SI/Tn curve were calculated. Decreasing the CM concentration from 100% to 40% resulted in a decrease of SI(max) to 86.1% (mean). Further decreasing the CM concentration to 2.5% decreased SI(max) to 5.1% (mean). Altering the saline chaser volume had no significant effect on SI(max). Increasing the saline chaser injection rate had little effect (mean increase, 2.2%) on SI(max) when using ≥40% of CM. There was a larger effect (mean increase, 19.6%) when ≤20% of CM were used. Bolus time length was significantly shorter (P < 0.001), and area under the SI/T(n) curve was significantly smaller (P < 0.01) for the CM protocols followed by a saline chaser injected at 6 mL/s compared with a saline chaser injected at 2 mL/s. With 40% of CM and a fast saline chaser, SImax close to that with undiluted CM can be achieved. An increased saline chaser injection rate has a more pronounced effect on

  14. Aortoiliac stenooculusive disease and aneurysms. Screening with non-contrast enhanced two-dimensional cardiac gated cine phase contrast MR angiography with multiple velocity encoded values and cardiac gated two-dimensional time-of-flight MR angiography

    International Nuclear Information System (INIS)

    Naganawa, Shinji; Koshikawa, Tokiko; Kato, Katsuhiko

    2001-01-01

    To evaluate the performance of two-dimensional cine phase contrast MRA with multi-velocity encoded values (multi-VENC cine PC) and ECG-gated two-dimensional time-of-flight MRA (ECG-2D-TOF) for the detection of stenoocclusive lesions and aneurysms in the aortoiliac area, when each method was used individually and when the two methods were used together. Forty-one patients were included in this study. Multi-VENC cine PC and ECG-2D-TOF were obtained first, then contrast enhanced three-dimensional magnetic resonance angiography (CE-3D-MRA) was performed as the standard of reference. Two observers reviewed the images separately without knowledge of patients' symptoms or histories. Sensitivities and specificities were obtained separately for stenooclusive lesions and aneurysms by two reviewers. When the two methods were applied together, high sensitivities (93.0 by observer 1 and 91.9% by observer 2) and adequate specificities (87.6 and 82.3%) were obtained for stenoocclusive lesions. For aneurysms, moderate to high sensitivities (91.1 and 71.1%) and high specificities (98.8 and 99.4%) were obtained. These results suggest that the performance of two non-contrast enhanced MRA techniques may be valuable as a screening tool when the two methods are applied together. (author)

  15. Low Z elements (Mg, Al, and Si) K-edge X-ray absorption spectroscopy in minerals and disordered systems

    International Nuclear Information System (INIS)

    Ildefonse, P.; Calas, G.; Flank, A.M.; Lagarde, P.

    1995-01-01

    Soft X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy have been performed at the Mg-, Al- and Si-K edges in order to establish the ability of this spectroscopy to derive structural information in disordered solids such as glasses and gels. Mg- and Al-K XANES are good structural probes to determine the coordination state of these elements in important minerals, glasses and gels. In a CaO-MgO-2SiO 2 glass Mg XANES spectra differ from that found in the crystalline equivalent, with a significant shift of the edge maxima to lower energy, consistent with a CN lower than 6. Mg-EXAFS on the same sample are in agreement and indicate the presence of 5-coordinated Mg with Mg-O distances of 2.01 A. In aluminosilicate gels, Al-K XANES has been used to investigate the [4]Al/Al total ratios. These ratios increase as the Al/Si ratios decrease. Aluminosilicate and ferric-silicate gels were studied by using Si-K edge XANES. XANES spectra differ significantly among the samples studied. Aluminosilicate gels with Al/Si=1 present a different Al and Si local environment from that known in clay minerals with the same Al/Si ratio. The gel-to-mineral transformation thus implies a dissolution-recrystallization mechanism. On the contrary, ferric-silicate gel presents a Si local environment close to that found in nontronite which may be formed by a long range ordering of the initial gels. (orig.)

  16. Low Z elements (Mg, Al, and Si) K-edge X-ray absorption spectroscopy in minerals and disordered systems

    Science.gov (United States)

    Ildefonse, Ph.; Calas, G.; Flank, A. M.; Lagarde, P.

    1995-05-01

    Soft X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy have been performed at the Mg-, Al- and Si-K edges in order to establish the ability of this spectroscopy to derive structural information in disordered solids such as glasses and gels. Mg- and Al-K XANES are good structural probes to determine the coordination state of these elements in important minerals, glasses and gels. In a CaOsbnd MgOsbnd 2SiO2 glass Mg XANES spectra differ from that found in the crystalline equivalent, with a significant shift of the edge maxima to lower energy, consistent with a CN lower than 6. Mg-EXAFS on the same sample are in agreement and indicate the presence of 5-coordinated Mg with Mgsbnd O distances of 2.01Å. In aluminosilicate gels, Alsbnd K XANES has been used to investigate the [4]Al/Altotal ratios. These ratios increase as the Al/Si ratios decrease. Aluminosilicate and ferric-silicate gels were studied by using Sisbnd K edge XANES. XANES spectra differ significantly among the samples studied. Aluminosilicate gels with Al/Si= 1 present a different Al and Si local environment from that known in clay minerals with the same Al/Si ratio. The gel-to-mineral transformation thus implies a dissolution-recrystallization mechanism. On the contrary, ferric-silicate gel presents a Si local environment close to that found in nontronite which may be formed by a long range ordering of the initial gels.

  17. The local structure of Ca-Na pyroxenes. 2-Xanes studies at the Mg and A1 K edges

    International Nuclear Information System (INIS)

    Mottana, A.; Cibin, G.; Paris, E.; Giuli, G.; Florence Univ., Florence

    1999-01-01

    X-ray absorption spectra at the Mg and A1 K edges have been recorded on synthetic endmember diopside (Di) and jadeite (Jd) and on a series of natural Fe-poor Ca-Na clinopyroxenes compositionally straddling the Jd-Di join. The spectra of C2/c members of the series (C-omphacites) are different from having P2/n symmetry (P-omphacites). Differences can be explained by theoretical spectra calculated via the multiple-scattering formalism on atomic clusters with at least 89 atoms, extending to a. 0.62 nm away from the Mg viz. A1 absorber: Xanes detects in these systems medium- rather than short-range order-disorder relationships. Near-edge features of C-omphacites reflect the single-type of octahedral arrangement of the back scattering nearest-neighbours (six O atoms) around the absorber (Mg resp. A1) at the centre of the cluster (site M1). Others arise again from medium-range order. P-omphacites show more complicated spectra than C-omphacites. Their additional features reflect the increased local disorder around the probed atom (Mg resp. A1) induced by the two alternative M1, M11 configurations of the six O atoms forming the first co-ordination spheres. Mg and A1 are confirmed to be preferentially partitioned in the M1 resp. M11 site of the P-omphacite crystal structure, however never exclusively, but in a ratio close to 85:15 (plus or minus 10%) that implies a certain degree of local disorder. Changes in the relative heights of some prominent features are more evident in the A1 than in the Mg K-edge spectra. They are diagnostic to qualitatively distinguish C-from P-omphacites

  18. The local structure of Ca-Na pyroxenes. 2-Xanes studies at the Mg and A1 K edges

    Energy Technology Data Exchange (ETDEWEB)

    Mottana, A. [Rome Univ. Roma Tre, Rome (Italy). Dipt. di Scienze Geologiche; Murata, T. [Kyoto University of Education, Kyoto (Japan). Dept. of Physics; Marcelli, A. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Wu, Z.Y. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati]|[Laboratoire Piere Suee, Gif-sur Yvette Cedex, (France); Cibin, G. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Paris, E. [Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra; Giuli, G. [Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra]|[Florence Univ., Florence (Italy). Dipt. di Scienze della Terra

    1999-07-01

    X-ray absorption spectra at the Mg and A1 K edges have been recorded on synthetic end member diopside (Di) and jadeite (Jd) and on a series of natural Fe-poor Ca-Na clinopyroxenes compositionally straddling the Jd-Di join. The spectra of C2/c members of the series (C-omphacites) are different from having P2/n symmetry (P-omphacites). Differences can be explained by theoretical spectra calculated via the multiple-scattering formalism on atomic clusters with at least 89 atoms, extending to a. 0.62 nm away from the Mg viz. A1 absorber: Xanes detects in these systems medium- rather than short-range order-disorder relationships. Near-edge features of C-omphacites reflect the single-type of octahedral arrangement of the back scattering nearest-neighbours (six O atoms) around the absorber (Mg resp. A1) at the centre of the cluster (site M1). Others arise again from medium-range order. P-omphacites show more complicated spectra than C-omphacites. Their additional features reflect the increased local disorder around the probed atom (Mg resp. A1) induced by the two alternative M1, M11 configurations of the six O atoms forming the first co-ordination spheres. Mg and A1 are confirmed to be preferentially partitioned in the M1 resp. M11 site of the P-omphacite crystal structure, however never exclusively, but in a ratio close to 85:15 (plus or minus 10%) that implies a certain degree of local disorder. Changes in the relative heights of some prominent features are more evident in the A1 than in the Mg K-edge spectra. They are diagnostic to qualitatively distinguish C-from P-omphacites.

  19. Comparison of high-resolution contrast-enhanced 3D MRA with digital subtraction angiography in the evaluation of hepatic arterial anatomy

    International Nuclear Information System (INIS)

    Matoba, M.; Tonami, H.; Kuginuki, M.; Yokota, H.; Takashima, S.; Yamamoto, I.

    2003-01-01

    AIM: To evaluate the validity of high-resolution contrast-enhanced three-dimensional magnetic resonance angiography (MRA) in defining hepatic arterial anatomy and to compare this with digital subtraction angiography (DSA). MATERIALS AND METHODS: MRA and DSA were performed in 30 patients. MRA was performed with breath-hold, gadolinium-enhanced, three-dimensional, fast low-angle shot sequence with a 512 pixel matrix. MRA was compared with DSA in terms of image quality and depiction of hepatic arterial anatomy. The agreement in image quality between MRA and DSA was determined with the kappa statistic. RESULTS: With respect to image quality, there was excellent or good correlation between MRA and DSA for the common hepatic artery (κ=0.85), proper hepatic artery (κ=0.72), gastroduodenal artery (κ=0.70), left hepatic artery (κ=0.49), left gastric artery (κ=0.50), splenic artery (κ=0.84), and superior mesenteric artery (κ=0.88). Poor correlation was found for the right hepatic artery (κ=0.18) and right gastric artery (κ=0.38). With regard to hepatic arterial anatomy, MRA correlated correctly with DSA in 28 of the 29 cases, i.e. 97% of patients. CONCLUSION: MRA is a useful technique for the evaluation of the hepatic artery, and for the vast majority of patients, MRA can replace intra-arterial DSA

  20. Evaluation of three-dimensional gadolinium-enhanced MR angiography using the timing monitoring function of contrast material (Smart Prep technique)

    International Nuclear Information System (INIS)

    Tsuchihashi, Toshio; Sasaki, Sadayuki; Yoshizawa, Satoshi; Maki, Toshio; Kitagawa, Matsuo; Suzuki, Takeshi

    1998-01-01

    The Smart Prep technique for gadolinium-enhanced three-dimensional MR angiography (3D-MRA) was evaluated in clinical practice. By monitoring signal intensity in the region of interest (tracking volume) in the target vessel, start timing after contrast injection can be optimized using the Smart Prep technique. Successful triggering was obtained in the chest, abdomen, and pelvic areas in about 80% of the cases in this study. Failures with this technique were mainly due to changes in tracking volume caused by patient motion and respiration. We noted that the scan started earlier than expected in the thoracic aorta when part of the heart or pulmonary artery was included in the tracking volume. Thus, care must be taken in defining the size and location of the tracking volume in gadolinium-enhanced 3D-MRA using the Smart Prep technique. (author)

  1. Digital subtraction angiography (DSA)

    International Nuclear Information System (INIS)

    Ludwig, J.W.; Eikelboom, B.C.; Van Schaik, C.C.; Taams, A.J.; Teeuwen, C.

    1985-01-01

    Besides the non-invasive techniques, angiography remains essential. The disadvantages of angiography are the complexity of the procedure and the possibility of complications. Digital subtraction angiography (DSA) is a considerable improvement in the examination of vessels. In DSA, subtraction combined with enhancement of the signals allows the use of intravenous injection to obtain good images of the arteries. However, when the contrast material is supplied intravenously, a rather large amount of contrast material is necessary to obtain images of good quality. Quantities of 30-40 cc of contrast material are required. The advantage of the intravenous injection of contrast material rather than the use of a catheter to deliver the contrast material in loco is that it is almost non-invasive thus circumventing the complications caused by catheter manipulation in the arterial system. This makes it possible to apply this method on an out-patient basis. DSA can also be applied with intra-arterial selective injection of the contrast material. In this case, the strong enhancement with DSA allows the use of a small quantity of contrast material while still obtaining images of the vessels with good contrast definition

  2. Gadofosveset-enhanced magnetic resonance angiography as a means of evaluating pulmonary arteriovenous malformation: a case report.

    Science.gov (United States)

    Pressacco, Josephine; Papas, Konstantin

    2012-07-01

    This case report is a unique presentation of a new potential indication for Gadofosvest (Ablavar), a blood pool contrast agent for magnetic resonance angiography (MRA). Ablavar is an excellent MRA contrast agent because it provides optimal contrast opacification of both the arterial and venous system, unlike the conventional extracellular agents that are used for arterial imaging only. The present case report demonstrates the ability of Ablavar to demonstrate pulmonary arteriovenous malformation (AVM), showing both its arterial feeders as well as its venous drainage tract. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

  3. Improving the image quality of contrast-enhanced MR angiography by automated image registration: A prospective study in peripheral arterial disease of the lower extremities

    International Nuclear Information System (INIS)

    Menke, Jan

    2010-01-01

    Objective: If a patient has moved during digital subtraction angiography (DSA), manual pixel shift can improve the image quality. This study investigated whether such image registration can also improve the quality of contrast-enhanced magnetic resonance angiography (MRA) in patients with peripheral arterial disease of the lower extremities. Materials and methods: 404 leg MRAs of patients likely to have peripheral artery disease were included in this prospective study. The standard non-registered MRAs were compared to automatically linear, affine and warp registered MRAs by four image quality parameters, including the vessel detection probability (VDP) in maximum intensity projection (MIP) images and contrast-to-noise ratios (CNR). The different registration types were compared by analysis of variance. Results: All studied image quality parameters showed similar trends. Generally, registration improved the leg MRA quality significantly (P < 0.05). The 12% of lower legs with a body shift of 1 mm or more showed the highest gain in image quality when using linear registration instead of no registration, with an average VDP gain of 20-49%. Warp registration improved the image quality slightly further. Conclusion: Automated image registration can improve the MRA image quality especially in the lower legs, which is comparable to the effect of pixel shift in DSA.

  4. Role of high resolution contrast-enhanced magnetic resonance angiography (HR CeMRA) in management of arterial complications of the renal transplant

    International Nuclear Information System (INIS)

    Ismaeel, M. Maged; Abdel-Hamid, Azza

    2011-01-01

    Introduction: Transplant renal artery (RA) stenosis (TRAS) is the most frequent posttransplantation vascular complication. Contrast enhanced magnetic resonance (CeMRA) angiography has been established as the preferred imaging technique for the evaluation of TRAS because it does not require the use of iodinated contrast material and does not expose the patient to ionizing radiation. Digital subtraction angiography (DSA) is the gold standard in the evaluation of arterial tree of the renal allograft. Aim of the work: This study was carried out to assess the accuracy of CeMRA in the detection of arterial complications after renal transplantation. Patients and methods: Thirty renal transplant patients with suspected arterial complications in which both CeMRA and DSA were performed were included in the study. The HR CeMRA shows 93.7% sensitivity, 80% specificity, 88.2% positive predictive value, 88.9% negative predictive value and 88.5% accuracy. Conclusion: HR CeMRA is an accurate reliable tool in the assessment of arterial complications after renal transplantation. It may replace DSA as a diagnostic modality with reservation of interventional techniques for endovascular treatment of suitable cases.

  5. Role of high resolution contrast-enhanced magnetic resonance angiography (HR CeMRA) in management of arterial complications of the renal transplant

    Energy Technology Data Exchange (ETDEWEB)

    Ismaeel, M. Maged [Suez Canal University (Egypt); Abdel-Hamid, Azza, E-mail: azza4951@hotmail.com [Suez Canal University (Egypt)

    2011-08-15

    Introduction: Transplant renal artery (RA) stenosis (TRAS) is the most frequent posttransplantation vascular complication. Contrast enhanced magnetic resonance (CeMRA) angiography has been established as the preferred imaging technique for the evaluation of TRAS because it does not require the use of iodinated contrast material and does not expose the patient to ionizing radiation. Digital subtraction angiography (DSA) is the gold standard in the evaluation of arterial tree of the renal allograft. Aim of the work: This study was carried out to assess the accuracy of CeMRA in the detection of arterial complications after renal transplantation. Patients and methods: Thirty renal transplant patients with suspected arterial complications in which both CeMRA and DSA were performed were included in the study. The HR CeMRA shows 93.7% sensitivity, 80% specificity, 88.2% positive predictive value, 88.9% negative predictive value and 88.5% accuracy. Conclusion: HR CeMRA is an accurate reliable tool in the assessment of arterial complications after renal transplantation. It may replace DSA as a diagnostic modality with reservation of interventional techniques for endovascular treatment of suitable cases.

  6. Pediatric angiography

    International Nuclear Information System (INIS)

    Fitz, A.R.

    1987-01-01

    Angiography of the cerebral and visceral arterial systems is performed much less frequently than it was before the advent of computed tomographic scanning (CT). Most institutions have experienced at least a 50% reduction in the number of angiograms performed since installing a CT scanner. However, angiography still plays an important role in the confirmation of diagnoses made using a scanner, and in providing valuable information to the surgeon prior to excision of tumors or the repair of traumatized organs. Recently a number of sophisticated therapeutic procedures requiring vascular catheterization and the injection of contrast agents have been developed. In these procedures catheters are selectively placed in blood vessels perfusing a pathological process, such as an arteriovenous malformation, or at the site of an arterial stenosis; embolization of the arteriovenous malformation or tumor, or dilatation of the stenotic segment, is then performed. Whether the vessel catheterization is for diagnostic or therapeutic purposes, the basic approach is the same, and the technologist's duties are similar. The principal difference between a diagnostic and a therapeutic procedure is the length of time required to carry out the study; therapeutic procedures often require significantly longer periods of general anesthesia or sedation than do diagnostic studies

  7. Magnetic resonance angiography vs. angiography in tetralogy of Fallot.

    Science.gov (United States)

    Rao, Uppalapati Venkateswara; Vanajakshamma, Velam; Rajasekhar, Durgaprasad; Lakshmi, Amancharla Yadagiri; Reddy, Reddivari Niranjan

    2013-08-01

    : To determine whether gadolinium-enhanced three-dimensional magnetic resonance angiography can provide a noninvasive alternative to diagnostic catheterization for evaluation of pulmonary artery anatomy in tetralogy of Fallot. Thirty-five consecutive patients with tetralogy of Fallot, who attended the cardiology outpatient department between January 2008 and December 2009, were included in the study. There were 21 males and 14 females, with a mean age of 9 ± 4.15 years (range, 3-21 years). Thirty-two patients had tetralogy of Fallot with varying severities of valvular and infundibular stenosis. Three patients had tetralogy of Fallot with pulmonary atresia. All patients underwent both cardiac catheterization with X-ray angiography and 3-dimensional magnetic resonance angiography within one month. Measurements of right and left pulmonary arteries and aortopulmonary collaterals were equal by both methods. There was a good correlation between magnetic resonance angiography and catheterization measurements of branch pulmonary arteries. Gadolinium-enhanced three-dimensional magnetic resonance angiography can be used as a reliable noninvasive alternative to X-ray cineangiography for delineation of pulmonary arterial anatomy in sick infants and young children, obviating the need for catheterization.

  8. Contrast-enhanced magnetic resonance angiography for the detection of crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with operative findings.

    Science.gov (United States)

    Calder, Alistair D; Hiorns, Melanie P; Abhyankar, Aruna; Mushtaq, Imran; Olsen, Oystein E

    2007-04-01

    Crossing renal vessels (CRV) are associated with ureteropelvic junction (UPJ) obstruction, particularly when presentation is beyond the neonatal period. Their presence may influence surgical management. To evaluate the accuracy of contrast-enhanced magnetic resonance angiography (CE-MRA) in the identification of CRV in children requiring surgical treatment of symptomatic UPJ obstruction, against a gold standard of laparoscopic or open surgical findings. We reviewed CE-MRA studies (3-D T2-weighted turbo spin-echo and multiphase 3-D spoiled gradient echo following intravenous gadolinium administration) of 14 children, age range 6-15 years, performed prior to surgery for suspected CRV-related UPJ obstruction. Consensus reviews of the CE-MRA studies were compared with surgical findings. CE-MRA demonstrated CRV at the level of the obstruction in nine and no crossing vessels in five children. These were all verified intraoperatively (chi2=14.0; Pchildren older than 6 years with symptomatic UPJ obstruction.

  9. A new device expanding operability of fingertip replantation: subzone 1 fingertip replantation assisted by non-enhanced angiography in a 2-year-old boy.

    Science.gov (United States)

    Yoshimatsu, Hidehiko; Yamamoto, Takumi; Seki, Yukio; Narushima, Mitsunaga; Iida, Takuya; Koshima, Isao

    2012-11-01

    Fingertip replantation in young children is difficult, especially in cases with amputation at subzone 1. Replantation is preferred whenever possible, but the identification of vessels of operative size can be very challenging. Non-enhanced angiography (NEA; Genial Viewer; Genial Light, Shizuoka, Japan) emits infrared light with the wavelength of 850 nm, which is exclusively absorbed by haemoglobin. The light penetrates the bones and other soft tissues, effectively visualising vessels containing blood, and the image is shown in real time on the screen of a laptop computer. We present a case in which preoperative NEA visualised vessels in the amputated fingertip, allowing a successful replantation in a 2-year-old boy. By taking the guesswork out of vessel localisation, NEA can be useful in expanding operability of replantation surgery in fingertip amputations. Copyright © 2012 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  10. Sulfur K-edge absorption spectroscopy on selected biological systems; Schwefel-K-Kanten-Absorptionsspektroskopie an ausgewaehlten biologischen Systemen

    Energy Technology Data Exchange (ETDEWEB)

    Lichtenberg, Henning

    2008-07-15

    Sulfur is an essential element in organisms. In this thesis investigations of sulfur compounds in selected biological systems by XANES (X-ray Absorption Near Edge Structure) spectroscopy are reported. XANES spectroscopy at the sulfur K-edge provides an excellent tool to gain information about the local environments of sulfur atoms in intact biological samples - no extraction processes are required. Spatially resolved measurements using a Kirkpatrick-Baez mirror focusing system were carried out to investigate the infection of wheat leaves by rust fungi. The results give information about changes in the sulfur metabolism of the host induced by the parasite and about the extension of the infection into visibly uninfected plant tissue. Furthermore, XANES spectra of microbial mats from sulfidic caves were measured. These mats are dominated by microbial groups involved in cycling sulfur. Additionally, the influence of sulfate deprivation and H{sub 2}S exposure on sulfur compounds in onion was investigated. To gain an insight into the thermal degradation of organic material the influence of roasting of sulfur compounds in coffee beans was studied. (orig.)

  11. Resonant soft x-ray reflectivity of Me/B4C multilayers near the boron K edge

    Energy Technology Data Exchange (ETDEWEB)

    Ksenzov, Dmitriy; Schlemper, Christoph; Pietsch, Ullrich

    2010-09-01

    Energy dependence of the optical constants of boron carbide in the short period Ru/B4C and Mo/B4C multilayers (MLs) are evaluated from complete reflectivity scans across the boron K edge using the energy-resolved photon-in-photon-out method. Differences between the refractive indices of the B4Cmaterial inside and close to the surface are obtained from the peak profile of the first order ML Bragg peak and the reflection profile near the critical angle of total external reflection close to the surface. Where a Mo/B4C ML with narrow barrier layers appears as a homogeneous ML at all energies, a Ru/B4C ML exhibits another chemical nature of boron at the surface compared to the bulk. From evaluation of the critical angle of total external reflection in the energy range between 184 and 186 eV, we found an enriched concentration of metallic boron inside the Ru-rich layer at the surface, which is not visible in other energy ranges.

  12. High-resolution molybdenum K-edge X-ray absorption spectroscopy analyzed with time-dependent density functional theory.

    Science.gov (United States)

    Lima, Frederico A; Bjornsson, Ragnar; Weyhermüller, Thomas; Chandrasekaran, Perumalreddy; Glatzel, Pieter; Neese, Frank; DeBeer, Serena

    2013-12-28

    X-ray absorption spectroscopy (XAS) is a widely used experimental technique capable of selectively probing the local structure around an absorbing atomic species in molecules and materials. When applied to heavy elements, however, the quantitative interpretation can be challenging due to the intrinsic spectral broadening arising from the decrease in the core-hole lifetime. In this work we have used high-energy resolution fluorescence detected XAS (HERFD-XAS) to investigate a series of molybdenum complexes. The sharper spectral features obtained by HERFD-XAS measurements enable a clear assignment of the features present in the pre-edge region. Time-dependent density functional theory (TDDFT) has been previously shown to predict K-pre-edge XAS spectra of first row transition metal compounds with a reasonable degree of accuracy. Here we extend this approach to molybdenum K-edge HERFD-XAS and present the necessary calibration. Modern pure and hybrid functionals are utilized and relativistic effects are accounted for using either the Zeroth Order Regular Approximation (ZORA) or the second order Douglas-Kroll-Hess (DKH2) scalar relativistic approximations. We have found that both the predicted energies and intensities are in excellent agreement with experiment, independent of the functional used. The model chosen to account for relativistic effects also has little impact on the calculated spectra. This study provides an important calibration set for future applications of molybdenum HERFD-XAS to complex catalytic systems.

  13. Preoperative evaluation of living renal donors: value of contrast-enhanced 3D magnetic resonance angiography and comparison of three rendering algorithms

    International Nuclear Information System (INIS)

    Fink, C.; Hallscheidt, P.J.; Hosch, W.P.; Kauffmann, G.W.; Duex, M.; Ott, R.C.; Wiesel, M.

    2003-01-01

    The aim of this study was to assess the value of contrast-enhanced three-dimensional MR angiography (CE 3D MRA) in the preoperative assessment of potential living renal donors, and to compare the accuracy for the depiction of the vascular anatomy using three different rendering algorithms. Twenty-three potential living renal donors were examined with CE 3D MRA (TE/TR=1.3 ms/3.7 ms, field of view 260-320 x 350 mm, 384-448 x 512 matrix, slab thickness 9.4 cm, 72 partitions, section thickness 1.3 mm, scan time 24 s, 0.1 mmol/kg body weight gadobenate dimeglumine). Magnetic resonance angiography data sets were processed with maximum intensity projection (MIP), volume rendering (VR), and shaded-surface display (SSD) algorithms. The image analysis was performed independently by three MR-experienced radiologists recording the number of renal arteries, the presence of early branching or vascular pathology. The combination of digital subtraction angiography (DSA) and intraoperative findings served as the gold standard for the image analysis. In total, 52 renal arteries were correspondingly observed in 23 patients at DSA and surgery. Other findings were 3 cases of early branching of the renal arteries, 4 cases of arterial stenosis and 1 case of bilateral fibromuscular dysplasia. With MRA source data all 52 renal arteries were correctly identified by all readers, compared with 51 (98.1%), 51-52 (98.1-100%) and 49-50 renal arteries (94.2-96.2%) with the MIP, VR and SSD projections, respectively. Similarly, the sensitivity, specificity and accuracy was highest with the MRA source data followed by MIP, VR and SSD. Time requirements were lowest for the MIP reconstructions and highest for the VR reconstructions. Contrast-enhanced 3D MRA is a reliable, non-invasive tool for the preoperative evaluation of potential living renal donors. Maximum intensity projection is favourable for the processing of 3D MRA data, as it has minimal time and computational requirements, while having

  14. Preoperative evaluation of living renal donors: value of contrast-enhanced 3D magnetic resonance angiography and comparison of three rendering algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Fink, C. [Abteilung Radiologische Diagnostik, Radiologische Universitaetsklinik Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany); Abteilung Onkologische Diagnostik und Therapie, Forschungsschwerpunkt Radiologische Diagnostik und Therapie, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Hallscheidt, P.J.; Hosch, W.P.; Kauffmann, G.W.; Duex, M. [Abteilung Radiologische Diagnostik, Radiologische Universitaetsklinik Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany); Ott, R.C.; Wiesel, M. [Abteilung Urologie und Poliklinik, Chirurgische Universitaetsklinik Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany)

    2003-04-01

    The aim of this study was to assess the value of contrast-enhanced three-dimensional MR angiography (CE 3D MRA) in the preoperative assessment of potential living renal donors, and to compare the accuracy for the depiction of the vascular anatomy using three different rendering algorithms. Twenty-three potential living renal donors were examined with CE 3D MRA (TE/TR=1.3 ms/3.7 ms, field of view 260-320 x 350 mm, 384-448 x 512 matrix, slab thickness 9.4 cm, 72 partitions, section thickness 1.3 mm, scan time 24 s, 0.1 mmol/kg body weight gadobenate dimeglumine). Magnetic resonance angiography data sets were processed with maximum intensity projection (MIP), volume rendering (VR), and shaded-surface display (SSD) algorithms. The image analysis was performed independently by three MR-experienced radiologists recording the number of renal arteries, the presence of early branching or vascular pathology. The combination of digital subtraction angiography (DSA) and intraoperative findings served as the gold standard for the image analysis. In total, 52 renal arteries were correspondingly observed in 23 patients at DSA and surgery. Other findings were 3 cases of early branching of the renal arteries, 4 cases of arterial stenosis and 1 case of bilateral fibromuscular dysplasia. With MRA source data all 52 renal arteries were correctly identified by all readers, compared with 51 (98.1%), 51-52 (98.1-100%) and 49-50 renal arteries (94.2-96.2%) with the MIP, VR and SSD projections, respectively. Similarly, the sensitivity, specificity and accuracy was highest with the MRA source data followed by MIP, VR and SSD. Time requirements were lowest for the MIP reconstructions and highest for the VR reconstructions. Contrast-enhanced 3D MRA is a reliable, non-invasive tool for the preoperative evaluation of potential living renal donors. Maximum intensity projection is favourable for the processing of 3D MRA data, as it has minimal time and computational requirements, while having

  15. Imaging Taurine in the Central Nervous System Using Chemically Specific X-ray Fluorescence Imaging at the Sulfur K-Edge

    Energy Technology Data Exchange (ETDEWEB)

    Hackett, Mark J.; Paterson, Phyllis G.; Pickering, Ingrid J.; George, Graham N. (Curtin U.); (Saskatchewan)

    2016-11-15

    A method to image taurine distributions within the central nervous system and other organs has long been sought. Since taurine is small and mobile, it cannot be chemically “tagged” and imaged using conventional immuno-histochemistry methods. Combining numerous indirect measurements, taurine is known to play critical roles in brain function during health and disease and is proposed to act as a neuro-osmolyte, neuro-modulator, and possibly a neuro-transmitter. Elucidation of taurine’s neurochemical roles and importance would be substantially enhanced by a direct method to visualize alterations, due to physiological and pathological events in the brain, in the local concentration of taurine at or near cellular spatial resolution in vivo or in situ in tissue sections. We thus have developed chemically specific X-ray fluorescence imaging (XFI) at the sulfur K-edge to image the sulfonate group in taurine in situ in ex vivo tissue sections. To our knowledge, this represents the first undistorted imaging of taurine distribution in brain at 20 μm resolution. We report quantitative technique validation by imaging taurine in the cerebellum and hippocampus regions of the rat brain. Further, we apply the technique to image taurine loss from the vulnerable CA1 (cornus ammonis 1) sector of the rat hippocampus following global brain ischemia. The location-specific loss of taurine from CA1 but not CA3 neurons following ischemia reveals osmotic stress may be a key factor in delayed neurodegeneration after a cerebral ischemic insult and highlights the significant potential of chemically specific XFI to study the role of taurine in brain disease.

  16. A contrast enhancement and scanning techniques for CT angiography of head and neck. One phase injection method for simultaneous imaging of vessels and tumor

    International Nuclear Information System (INIS)

    Morita, Yasuhiko; Indo, Hiroko; Noikura, Takenori

    1999-01-01

    We report on a method of CT-Angiography useful for examining lesion of the head and neck using three-dimensional images and measured CT value. This study focused on some of the important blood vessels in the head and neck. The aim of this method was to obtain high-contrast enhancement for both vessels and tumors at same time. A total amount of 100 ml nonionic contrast media (Omnipaque 240, 240 mg iodine per milliliter, Daiichi seiyaku, Tokyo, Japan) was injected intravenously with a flow of 1.5 ml/sec. Spiral scans, 24 rotations with 24 seconds, were started at a time when remaining amount of contrast media had become 30 to 20 ml. All CT scans were performed using double speed spiral scan technique with a slice thickness of 2 to 3 mm and table speeds from 3 to 5 mm/rotation. The patients populations consisted of 9 men and 6 women who ranged in age from 37 to 85 years. Sixteen CT-angiography were performed according to this method. Mean CT values of major blood vessels were measured in order to find out threshold at the level of submandibular gland in 13 examinations for 12 subjects. Important vessels like the common, internal, and the external artery, internal and external jugular vein were clearly visible in all subjects. Three dimensional images of these vessels could also be reconstructed for 15 of the subjects. Mean CT values were 211 Hounsfield units (HU) and 209 HU for the right and left internal carotid artery, respectively, and 204 HU and 206 HU for the right and left external carotid artery, respectively. Mean CT values for right and left internal jugular vein were 195 HU and 194 HU respectively. Measured CT values at each important blood vessels showed this method could yields acceptable enhancements. Good enhancement effect of tumor and blood vessels in the same scan seems to be mutually incompatible. One very important trade-off is the early enhancement effect at blood vessels versus the late enhancement effect at tumors. The other important trade

  17. MRI angiography

    International Nuclear Information System (INIS)

    Poncelet, B.; Baleriiaux, D.; struyven, J.; Segebarth, C.

    1989-01-01

    In MRI angiography two basis images are measured which only differ by the signal intensity of the flowing blood in the vessels. Subtraction of these two images produces a high contrast-to-noise representation of the vessels. Contrast between stationary tissues and flowing blood is changed, for one image compared to the second one, using a selective modification of the phase of the signal from the flowing blood, and/or using a selective modification of its longitudinal magnetization: The macroscopic spin motions along the selection and the measurement gradient directions affect the phase of the nuclear signal; assuming constant velocity, the phase is proportional to the velocity and to the first moment of the gradient waveforms applied. This work concentrates on the generarion of MRI angiograms, following a phase-based approach, of the carotid bifurcation and of different intracranical regions including the carotid syphon and the circle of Willis. (author). 21 refs.; 3 figs

  18. Radionuclide angiography

    Energy Technology Data Exchange (ETDEWEB)

    Heidenreich, P; Klotz, E

    1983-12-27

    RNA of common and internal carotid arteries as well as main cerebral arteries is the first component of cerebral serial scintigraphy. It should be the first diagnostic step in suspected cerebrovascular disease. In contrast to computed tomography RNA gives valuable information about cerebrovascular processes without morphological defects. RNA is superior of Doppler sonography in the evaluation of intracranial vascular disease. The simple and non-invasive RNA of the kidneys should be performed after renal transplantation (i.e. differential diagnosis of acute rejection and acute tubular necrosis), in suspected renal artery stenosis, renal infarction or in arterio-venous malformation of the kidneys. RNA is valuable in suspected occlusion of the abdominal aorta (infra- or suprarenal), aortic aneurysm or in stenosis of arteries in the pelvis or thighs. Postoperative controls can be carried out as often as desired. However, it cannot replace contrast angiography if vascular reconstruction is planned.

  19. Measurement of X-ray mass attenuation coefficient of nickel around the K-edge using synchrotron radiation based X-ray absorption study

    International Nuclear Information System (INIS)

    Roy, Bunty Rani; Rajput, Parasmani; Jha, S.N.; Nageswara Rao, A.S.

    2015-01-01

    The work presents the X-ray absorption fine structure (XAFS) technique for measuring the X-ray mass attenuation coefficient of nickel metal foil in the X-ray energy range of 8271.2–8849.4 eV using scanning XAFS beam line (BL-09) at Indus-2 synchrotron radiation source facility, Raja Ramanna Centre for Advanced Technology (RRCAT) at Indore, India. The result represents the X-ray mass attenuation coefficient data for 0.02 mm thick Ni metal foil in the XAFS region of Ni K-edge. However, the results are compared to theoretical values using X-COM. There is a maximum deviation which is found exactly near the K-edge jump and decreases as we move away from the absorption edge. Oscillatory structure appears just above the observed absorption edge i.e., 8348.7 eV and is confined to around 250 eV above the edge. - Highlights: • Mass attenuation coefficient measurements of nickel using synchrotron radiation. • The measurements were taken exactly near the Ni K-edge at an energy step of 1 eV. • A maximum deviation is found near the K-edge

  20. Unexpected covalency from actinide 5f orbital interactions (An = Th, U, Np, Pu) determined from chlorine K-edge X-ray absorption spectroscopy and electronic structure theory

    International Nuclear Information System (INIS)

    Clark, D.L.; Batista, E.R.; Boland, K.S.

    2010-01-01

    We have employed Cl K-edge XAS and multiple levels of sophisticated electronic structure calculations on a series of simple octahedral light actinide (Th, U, Np, Pu) chloride salts, AnCl 6 n- in order to assess the relative roles of the valence 5f and 6d orbitals in chemical bonding. Chlorine K-edge X-ray absorption spectroscopy on AnCl 6 n- (An = Th, U, Np, Pu) systems indicates the presence of covalent interactions between both Cl 3p and An 5f and 6d orbitals, with the relative contributions changing across the series. Electronic structure calculations indicate the predominant covalent interactions are expected to occur through An-Cl bonding via t 1u and t 2u interactions with the An 5f orbitals, and through t 2g and e g interactions with An 6d orbitals. For the Cl K-edge data therefore, we expect bound state transitions from Cl 1s → e g (σ), t 2g (π), and t 1u (σ + π) orbitals. Qualitatively, the Cl K-edge data fulfills these expectations

  1. Origin of the chemical shift in X-ray absorption near-edge spectroscopy at the Mn K-Edge in manganese oxide compounds

    NARCIS (Netherlands)

    de Vries, AH; Hozoi, L.; Broer, R.

    2003-01-01

    The absorption edge in Mn K-edge X-ray absorption spectra of manganese oxide compounds shows a shift of several electronvolts in going from MnO through LaMnO3 to CaMnO3. On the other hand, in X-ray photoelectron spectra much smaller shifts are observed. To identify the mechanisms that cause the

  2. Digital subtraction angiography in ischemic cerebrovascular accidents

    Energy Technology Data Exchange (ETDEWEB)

    Manelfe, C.; Bonafe, A.; Ducos de Lahitte, M.; Rascol, A.; Prere, J.; Guiraud, B.; Marc-Vergnes, J.P. (Hopital Purpan, 31 - Toulouse (France))

    1983-12-29

    Recent advances in computer and radiological technology have permitted reassessment of intravenous angiography in the evaluation of cerebrovascular disorders. Although digital subtraction angiography is a relatively new technique, it has rapidly gained a widespread acceptance. It has extended the use of angiography to outpatients and to people in whom conventional angiography is contraindicated. This reliable, safe, and relatively noninvasive technique offers the user two benefits: real-time subtraction and enhanced image quality. The system allows angiographic evaluation of the extracranial and intracranial vessels by means of intravenous injection of contrast material. Extracranial studies clearly demonstrate stenoses and occlusions of the major cervicocephalic arteries. Intracranial studies usually detect major cerebrovascular occlusions and provide insight into the collateral flow patterns. Intravenous digital subtraction angiography permits accurate assessment of cervicocephalic vessels after surgical repair. Although intravenous digital subtraction angiography obviates the need for conventional angiography in many cases, movements from the patients, or superimposition of vascular structures can substantially degrade the quality of the images. Digital subtraction angiography with intra-arterial injection of contrast medium will be contemplated in patients with poor intravenous digital subtraction angiography studies prior to surgery.

  3. Digital subtraction angiography in ischemic cerebrovascular accidents

    International Nuclear Information System (INIS)

    Manelfe, C.; Bonafe, A.; Ducos de Lahitte, M.; Rascol, A.; Prere, J.; Guiraud, B.; Marc-Vergnes, J.P.

    1983-01-01

    Recent advances in computer and radiological technology have permitted reassessment of intravenous angiography in the evaluation of cerebrovascular disorders. Although digital subtraction angiography is a relatively new technique, it has rapidly gained a widespread acceptance. It has extended the use of angiography to outpatients and to people in whom conventional angiography is contraindicated. This reliable, safe, and relatively noninvasive technique offers the user two benefits: real-time subtraction and enhanced image quality. The system allows angiographic evaluation of the extracranial and intracranial vessels by means of intravenous injection of contrast material. Extracranial studies clearly demonstrate stenoses and occlusions of the major cervicocephalic arteries. Intracranial studies usually detect major cerebrovascular occlusions and provide insight into the collateral flow patterns. Intravenous digital subtraction angiography permits accurate assessment of cervicocephalic vessels after surgical repair. Although intravenous digital subtraction angiography obviates the need for conventional angiography in many cases, movements from the patients, or superimposition of vascular structures can substantially degrade the quality of the images. Digital subtraction angiography with intra-arterial injection of contrast medium will be contemplated in patients with poor intravenous digital subtraction angiography studies prior to surgery [fr

  4. Qualitative indices and enhancement rate of CT pulmonary angiography in patients with suspected pulmonary embolism: Comparison between test bolus and bolus-tracking methods

    Directory of Open Access Journals (Sweden)

    Maryam Moradi

    2016-01-01

    Full Text Available Background: The aim of the present study was to assess the qualitative indices and enhancement rate of computed tomographic pulmonary angiography (CTPA in patients with suspected pulmonary embolism using Test bolus and Bolus-tracking techniques. Materials and Methods: Fifty-two patients with suspected pulmonary embolism that passed informed consent were randomly divided in the two groups. In each group, demographic characteristics, qualitative indices, and enhancement rate of CTPA were recorded. Results: The diagnostic result obtained in majority of the participants in the two groups (88.5 % in Test bolus group vs. 73.1% in the Bolus tracking group. In the case of quantitative variables, no statistically significant differences were found between the groups (P > 0.05. The only statistically significant difference between the two groups is average of "X-ray dose". Conclusion: The results of our study show that there is no statistically significant difference between the Bolus Tracking and Test Bolus techniques for producing more homogeneous enhancement.

  5. The influence of coordination geometry and valency on the K-edge absorption near edge spectra of selected chromium compounds

    International Nuclear Information System (INIS)

    Pantelouris, A.; Modrow, H.; Pantelouris, M.; Hormes, J.; Reinen, D.

    2004-01-01

    X-ray absorption spectra at the chromium K-edge are reported for a number of selected chromium compounds of known chemical structure. The spectra were obtained with use of synchrotron radiation available at the ELectron Stretcher Accelerator ELSA in Bonn. The compounds studied include the tetrahedrally coordinated compounds Ca 2 Ge 0.8 Cr 0.2 O 4 , Ba 2 Ge 0.1 Cr 0.9 O 4 , Sr 2 CrO 4 , Ca 2 (PO 4 ) x (CrO 4 ) 1-x Cl (x=0.25,0.5), Ca 5 (CrO 4 ) 3 Cl, CrO 3 , the octahedrally coordinated compounds Cr(II)-acetate, CrCl 3 , CrF 3 , Cr 2 O 3 , KCr(SO 4 ) 2 · 12H 2 O, CrO 2 and cubic coordinated metallic chromium. In these compounds chromium exhibits a wide range of formal oxidation states (0 to VI). The absorption features in the near edge region are shown to be characteristic of the spatial environment of the absorbing atom. The occurrence of a single pre-edge line easily allows one to distinguish between tetrahedral and octahedral coordination geometry, whereas the energy position of the absorption edge is found to be very sensitive to the valency of the excited chromium atom. Calculations of the ionisation potential of Cr in different oxidation states using the non-relativistic Hartree-Fock method (Froese-Fischer) confirm that the ionisation limit shifts to higher energy with increasing Cr valency. More detailed information on the electronic structure of the different compounds is gained by real-space full multiple scattering calculations using the FEFF8 code

  6. The influence of coordination geometry and valency on the K-edge absorption near edge spectra of selected chromium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pantelouris, A.; Modrow, H.; Pantelouris, M.; Hormes, J.; Reinen, D

    2004-05-10

    X-ray absorption spectra at the chromium K-edge are reported for a number of selected chromium compounds of known chemical structure. The spectra were obtained with use of synchrotron radiation available at the ELectron Stretcher Accelerator ELSA in Bonn. The compounds studied include the tetrahedrally coordinated compounds Ca{sub 2}Ge{sub 0.8}Cr{sub 0.2}O{sub 4}, Ba{sub 2}Ge{sub 0.1}Cr{sub 0.9}O{sub 4}, Sr{sub 2}CrO{sub 4}, Ca{sub 2}(PO{sub 4}){sub x}(CrO{sub 4}){sub 1-x}Cl (x=0.25,0.5), Ca{sub 5}(CrO{sub 4}){sub 3}Cl, CrO{sub 3}, the octahedrally coordinated compounds Cr(II)-acetate, CrCl{sub 3}, CrF{sub 3}, Cr{sub 2}O{sub 3}, KCr(SO{sub 4}){sub 2} {center_dot} 12H{sub 2}O, CrO{sub 2} and cubic coordinated metallic chromium. In these compounds chromium exhibits a wide range of formal oxidation states (0 to VI). The absorption features in the near edge region are shown to be characteristic of the spatial environment of the absorbing atom. The occurrence of a single pre-edge line easily allows one to distinguish between tetrahedral and octahedral coordination geometry, whereas the energy position of the absorption edge is found to be very sensitive to the valency of the excited chromium atom. Calculations of the ionisation potential of Cr in different oxidation states using the non-relativistic Hartree-Fock method (Froese-Fischer) confirm that the ionisation limit shifts to higher energy with increasing Cr valency. More detailed information on the electronic structure of the different compounds is gained by real-space full multiple scattering calculations using the FEFF8 code.

  7. The influence of coordination geometry and valency on the K-edge absorption near edge spectra of selected chromium compounds

    Science.gov (United States)

    Pantelouris, A.; Modrow, H.; Pantelouris, M.; Hormes, J.; Reinen, D.

    2004-05-01

    X-ray absorption spectra at the chromium K-edge are reported for a number of selected chromium compounds of known chemical structure. The spectra were obtained with use of synchrotron radiation available at the ELectron Stretcher Accelerator ELSA in Bonn. The compounds studied include the tetrahedrally coordinated compounds Ca 2Ge 0.8Cr 0.2O 4, Ba 2Ge 0.1Cr 0.9O 4, Sr 2CrO 4, Ca 2(PO 4) x(CrO 4) 1- xCl ( x=0.25,0.5), Ca 5(CrO 4) 3Cl, CrO 3, the octahedrally coordinated compounds Cr(II)-acetate, CrCl 3, CrF 3, Cr 2O 3, KCr(SO 4) 2 · 12H 2O, CrO 2 and cubic coordinated metallic chromium. In these compounds chromium exhibits a wide range of formal oxidation states (0 to VI). The absorption features in the near edge region are shown to be characteristic of the spatial environment of the absorbing atom. The occurrence of a single pre-edge line easily allows one to distinguish between tetrahedral and octahedral coordination geometry, whereas the energy position of the absorption edge is found to be very sensitive to the valency of the excited chromium atom. Calculations of the ionisation potential of Cr in different oxidation states using the non-relativistic Hartree-Fock method (Froese-Fischer) confirm that the ionisation limit shifts to higher energy with increasing Cr valency. More detailed information on the electronic structure of the different compounds is gained by real-space full multiple scattering calculations using the FEFF8 code.

  8. Experimental evaluation of contrast-enhanced high-reselution MR angiography in the rabbit. Gd-DTPA versus Gd-DTPA polylysin

    International Nuclear Information System (INIS)

    Vogl, T.J.; Hoffmann, Y.; Juergens, M.; Weinmann, H.J.; Muehler, A.; Yucel, S.; Felix, R.

    1996-01-01

    In ten anesthesized rabbits (average weight 4.3 kg) MR angiography was performed using a 1.5 TMR unit (Magnetom SP63; Siemens Erlangen) and a CP head coil. Arterial MRA (FISP 3D TONE, TR/TE=33/8, Flip 20 ) and venous MRA (FLASH 2D, TR/TE=37/10, Flip 60 ) was performed before and after administration of the paramagnetic contrast agents Gd-DTPA (n=5) or Gd-DTPA polylysine (n=5) at a doseage of 0.1 mmol/kg. In all studies the single selections and the MIP reconstructions were evaluated quantitatively by measuring and calculating signal intensity, percentage enhancement, signal-to-noise and contrast-to-noise ratios. All studies were assessed qualitatively for visualization and distinction of the arterial and venous vessel system by three independent observers before and after the administration of contrast agent. Results: Gd-DTPA-enhanced arterial FISP 3D tone led to a percentage enhancement of 30% for the kidneys, 12% for the superior mesenteric artery, 18% for the deep circumfluent iliac artery, and 7% for the internal iliac artery. In FLASH 2D sequences Gd-DTPA led to a good C/N only for venous abdominal vessels like the left renal vein (2.59) and internal iliac vein (1.66); the percentage enhancement of these structures was between 16 and 21%. Qualitative comparison also showed no significant improvement after injection of Gd-DTPA. In FISP 3D TONE sequences Gd-DTPA polylysine led to a strong percentlage enhancement of right and left kidney (21 and 40%) and deep circumfluent iliac artery (17%). Qualitative evaluation showed improved delineation and contrast of low-diameter vessels, while the soft tissue was only slightly enhanced and did not impair vessel visualization. Conclusion: CMRA using Gd-DTPA and Gd-DTPA polylysine significantly improved the delineation of abdominal vessels, with Gd-DTPA polylysine being superior. (orig.) [de

  9. Non-contrast-enhanced MR angiography in critical limb ischemia: performance of quiescent-interval single-shot (QISS) and TSE-based subtraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Altaha, Mustafa A. [University Health Network, Department of Medical Imaging, Peter Munk Cardiac Centre, Toronto, Ontario (Canada); Jaskolka, Jeffrey D.; Tan, Kongteng; Menezes, Ravi J. [University Health Network, Department of Medical Imaging, Peter Munk Cardiac Centre, Toronto, Ontario (Canada); University of Toronto, Department of Medical Imaging, Toronto, Ontario (Canada); Rick, Manuela; Schmitt, Peter [Siemens Healthcare, Erlangen (Germany); Wintersperger, Bernd J. [University Health Network, Department of Medical Imaging, Peter Munk Cardiac Centre, Toronto, Ontario (Canada); University of Toronto, Department of Medical Imaging, Toronto, Ontario (Canada); Toronto General Hospital, Department of Medical Imaging, Toronto, Ontario (Canada)

    2017-03-15

    The aim of this study was to evaluate diagnostic performance of non-contrast-enhanced 2D quiescent-interval single-shot (QISS) and 3D turbo spin-echo (TSE)-based subtraction magnetic resonance angiography (MRA) in the assessment of peripheral arteries in patients with critical limb ischemia (CLI). Nineteen consecutive patients (74 % male, 72.8 ± 9.9 years) with CLI underwent 2D QISS and 3D TSE-based subtraction MRA at 1.5 T. Axial-overlapping QISS MRA (3 mm/2 mm; 1 x 1 mm{sup 2}) covered from the toes to the aortic bifurcation while coronal 3D TSE-based subtraction MRA (1.3 x 1.2 x 1.3 mm{sup 3}) was restricted to the calf only. MRA data sets (two readers) were evaluated for stenosis (≥50 %) and image quality. Results were compared with digital subtraction angiography (DSA). Two hundred and sixty-seven (267) segments were available for MRA-DSA comparison, with a prevalence of stenosis ≥50 % of 41.9 %. QISS MRA was rated as good to excellent in 79.5-96.0 % of segments without any nondiagnostic segments; 89.8-96.1 % of segments in 3D TSE-based subtraction MRA were rated as nondiagnostic or poor. QISS MRA sensitivities and specificities (segmental) were 92 % and 95 %, respectively, for reader one and 81-97 % for reader two. Due to poor image quality of 3D TSE-based subtraction MRA, diagnostic performance measures were not calculated. QISS MRA demonstrates excellent diagnostic performance and higher robustness than 3D TSE-based subtraction MRA in the challenging patient population with CLI. (orig.)

  10. Complications after liver transplantation: evaluation with magnetic resonance imaging, magnetic resonance cholangiography, and 3-dimensional contrast-enhanced magnetic resonance angiography in a single session

    International Nuclear Information System (INIS)

    Boraschi, P.; Donati, F.; Gigoni, R.; Salemi, S.; Urbani, L.; Filipponi, F.; Falaschi, F.; Bartolozzi, C.

    2008-01-01

    To evaluate a comprehensive magnetic resonance imaging (MRI) protocol as noninvasive diagnostic modality for simultaneous detection of parenchymal, biliary, and vascular complications after liver transplantation. Fifty-two liver transplant recipients suspected to have parenchymal, biliary, and (or) vascular complications underwent our MRI protocol at 1.5T unit using a phased array coil. After preliminary acquisition of axial T 1 w and T 2 w sequences, magnetic resonance cholangiography (MRC) was performed through a breath-hold, thin- and thick-slab, single-shot T 2 w sequence in the coronal plane. Contrast-enhanced magnetic resonance angiography (CEMRA) was obtained using a 3-dimensional coronal spoiled gradient-echo sequence, which enabled acquisition of 32 partitions 2.0 mm thick. A fixed dose of 20 ml gadobenate dimeglumine was administered at 2 mL/s. A post-contrast T 1 w sequence was also performed. Two observers in conference reviewed source images and 3-dimensional reconstructions to determine the presence of parenchymal, biliary, and vascular complications. MRI findings were correlated with surgery, endoscopic retrograde cholangiography (ERC), biopsy, digital subtraction angiography (DSA), and imaging follow-up. MRI revealed abnormal findings in 32 out of 52 patients (61%), including biliary complications (anastomotic and nonanastomotic strictures, and lithiasis) in 31, vascular disease (hepatic artery stenosis and thrombosis) in 9, and evidence of hepatic abscess and hematoma in 2. ERC confirmed findings of MRC in 30 cases, but suggested disease underestimation in 2. DSA confirmed 7 magnetic resonance angiogram (MRA) findings, but suggested disease overestimation in 2. MRI combined with MRC and CEMRA can provide a comprehensive assessment of parenchymal, biliary, and vascular complications in most recipients of liver transplantation. (author)

  11. Non-contrast-enhanced MR angiography in critical limb ischemia: performance of quiescent-interval single-shot (QISS) and TSE-based subtraction techniques

    International Nuclear Information System (INIS)

    Altaha, Mustafa A.; Jaskolka, Jeffrey D.; Tan, Kongteng; Menezes, Ravi J.; Rick, Manuela; Schmitt, Peter; Wintersperger, Bernd J.

    2017-01-01

    The aim of this study was to evaluate diagnostic performance of non-contrast-enhanced 2D quiescent-interval single-shot (QISS) and 3D turbo spin-echo (TSE)-based subtraction magnetic resonance angiography (MRA) in the assessment of peripheral arteries in patients with critical limb ischemia (CLI). Nineteen consecutive patients (74 % male, 72.8 ± 9.9 years) with CLI underwent 2D QISS and 3D TSE-based subtraction MRA at 1.5 T. Axial-overlapping QISS MRA (3 mm/2 mm; 1 x 1 mm 2 ) covered from the toes to the aortic bifurcation while coronal 3D TSE-based subtraction MRA (1.3 x 1.2 x 1.3 mm 3 ) was restricted to the calf only. MRA data sets (two readers) were evaluated for stenosis (≥50 %) and image quality. Results were compared with digital subtraction angiography (DSA). Two hundred and sixty-seven (267) segments were available for MRA-DSA comparison, with a prevalence of stenosis ≥50 % of 41.9 %. QISS MRA was rated as good to excellent in 79.5-96.0 % of segments without any nondiagnostic segments; 89.8-96.1 % of segments in 3D TSE-based subtraction MRA were rated as nondiagnostic or poor. QISS MRA sensitivities and specificities (segmental) were 92 % and 95 %, respectively, for reader one and 81-97 % for reader two. Due to poor image quality of 3D TSE-based subtraction MRA, diagnostic performance measures were not calculated. QISS MRA demonstrates excellent diagnostic performance and higher robustness than 3D TSE-based subtraction MRA in the challenging patient population with CLI. (orig.)

  12. Brain arteriovenous malformation diagnosis: value of time-resolved contrast-enhanced MR angiography at 3.0T compared to DSA

    International Nuclear Information System (INIS)

    Machet, A.; Kadziolka, K.; Robin, G.; Lanoix, O.; Pierot, L.; Portefaix, C.

    2012-01-01

    This study was conducted in order to evaluate the value of time-resolved contrast-enhanced magnetic resonance angiography (TR-CE-MRA) with a 3.0-T magnetic field compared to digital subtraction angiography (DSA) as the reference standard for the diagnosis of brain arteriovenous malformation (bAVM). Nineteen patients with 19 angiographically confirmed untreated bAVM were investigated with both DSA and TR-CE-MRA for the initial diagnosis. Examinations were compared by two independent readers. Interobserver agreement and intermodality agreement with respect to nidus size, arterial feeders, and venous drainage were determined using the K statistic test. Also, the quality of the TR-CE-MRA images was evaluated. Seventeen of the 19 bAVM (89.5%) detected with DSA were diagnosed with TR-CE-MRA. Interobserver agreement for TR-CE-MRA was good for nidus size, venous drainage, and arterial feeders (K = 0.75, 95% CI 0.50-1.00; K = 0.77, 95% CI 0.54-1.00; and K = 0.80, 95% CI 0.59-1.00 respectively). Intermodality agreement was good for nidus size and venous drainage (K = 0.75, 95% CI 0.49-1.00 and K = 0.77, 95% CI 0.54-1.00, respectively) and moderate for arterial feeders (K = 0.44, 95% CI 0.17-0.70). TR-CE-MRA at 3.0 T has a good sensitivity for bAVM detection and good agreement with DSA for determining nidus size and the type of venous drainage, suggesting that TR-CE-MRA is potentially a reliable tool for the diagnosis and assessment of bAVMs. However, it still suffers from low spatial resolution and vessel superposition, making differentiation of the arterial feeders of the nidus difficult at times. (orig.)

  13. Preliminary study of 3.0 T contrast-enhanced whole heart coronary MR angiography using 32-channel coils with high acceleration factor

    International Nuclear Information System (INIS)

    Yang Qi; Li Kuncheng; Du Xiangying; Ma Heng; An Jing; Li Han; Xu Dong; Bi Xiaoming; Li Debiao

    2010-01-01

    Objective: To evaluate the diagnostic accuracy of 3.0 T contrast enhanced (CE) whole-heart coronary MRA (CE MRA) using 32-channel coils with high acceleration factor. Methods: Sixty patients with suspected coronary artery disease who were scheduled for coronary angiography (CAG) underwent CE CMRA at 3.0 T MRI scanner. A 32-channel receiver coil was used for data acquisition. For image acquisition, an ECG triggered,navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence was used with an acceleration factor of three in the phase-encoding direction using GRAPPA reconstruction. Gd-BOPTA (0.15 mmol/kg body weight) was intravenously administered at a rate of 0.3 ml/s. The diagnostic accuracy in detecting significant stenoses (≥50% of vessel lumen) was evaluated using χ 2 test with X-ray angiography as the reference. Results: Whole-heart CE CMRA was successfully completed in 56 patients who were scheduled for CAG. The averaged imaging time was (6.0±1.3) min. 3.0 T CE CMRA using 32 channel coils correctly identified significant CAD in 28 patients and correctly ruled out CAD in 23 patients. The sensitivity and specificity were 93.3% and 88.5% respectively. Conclusion: Combined with dedicated 32-channel coils, 3.0 T CE CMRA allows significant reduction in imaging speed and reduced dose of the contrast agent. These improvements resulted in substantially improved overall accuracy of CE CMRA in detecting coronary artery disease. (authors)

  14. MR angiography

    International Nuclear Information System (INIS)

    Masaryk, T.J.; Ross, J.S.

    1991-01-01

    This paper reports on preliminary research and recent clinical experience which indicates that MR angiography can play a role in routine scanning by providing useful information regarding the anatomy of the cerebral circulation. Used in conjunction with conventional spin-echo studies it may improve the overall sensitivity and specificity of MRI in a cost-effective fashion. It does not, however, replace conventional arteriography at this time for either extracranial or intracranial disease. The use of intravascular contrast agents with new fast-scan techniques also provides dynamic information regarding tissue perfusion in a fashion analogous to that of xenon CT. While this work is preliminary, and the exact agents and mathematical models have yet to be defined, the ability to perform parenchymal, angiographic, and physiologic imaging at a single setting is potentially very powerful. Clearly, the role of MR flow techniques deserves further investigation into possible technical refinements, so that accuracy relative to other diagnostic studies and impact upon patient management can be assessed in a meaningful way

  15. Microembolism after cerebral angiography

    International Nuclear Information System (INIS)

    Manaka, Hiroshi; Sakai, Hideki; Nagata, Izumi

    2000-01-01

    Acute microemboli are detected more precisely with the recently developed diffusion-weighted MR imaging (DWI). We happened to obtain 24 DWIs after 350 diagnostic cerebral angiographies in 1999. DWIs after cerebral angiographies showed bright lesions in 7 patients (28%), of whom 6 had no neurological symptoms after cerebral angiography. Seven of the 24 patients had risk factors for arteriosclerosis. Only one patient had embolic events due to angiography. Microemboli related to cerebral angiographies are inevitable in some patients. Most are silent, however, we should investigate the cause of microemboli and should make cerebral angiography safer. (author)

  16. Angiography in angiology

    International Nuclear Information System (INIS)

    Zeitler, E.; Grosse-Vorholt, R.

    1980-01-01

    A review is given of recent developments in angiography including advances in the equipment, in the technique and in image processing. Indications for and interpretation of angiography are discussed and angiographic-therapeutic procedures are considered. (C.F.)

  17. A fundamental study of non-contrast enhanced MR angiography using ECG gated-3D fast spin echo at 3.0 T

    International Nuclear Information System (INIS)

    Nakato, Kengo; Hiai, Yasuhiro; Tomiguchi, Seiji

    2010-01-01

    Contrast-enhanced magnetic resonance angiography (CE-MRA) is frequently performed in body and extremity studies because of its superior ability to detect the vascular stenosis. However, nephrotoxicity of the contrast medium has been emphasized in recent years. Non-contrast MRA using the three-dimensional electrocardiogram-synchronized fast spin echo method (fresh blood imaging (FBI), non-contrast MRA of arteries and veins (NATIVE) and triggered acquisition non contrast enhancement MRA (TRANCE)) is recommended as a substitute for CE-MRA. There are a few reports in the literature that evaluate the detectability of vascular stenosis using non-contrast MRA on 3.0 T MRI. The purpose of this study was to evaluate the detectability of vascular stenosis using non-contrast MRA at 3.0 T with an original vascular phantom. The vascular phantom consisted of silicon tubes. 30% and 70% stenosis of luminal diameter were made. Each silicon tube connected a pump producing a pulsatile flow. A flowing material to was used in this study to show the similarity of the intensity to blood on MRI. MRA without a contrast medium (NATIVE sequence) were performed in the vascular phantom by changing the image matrix, static magnetic field strength and flow velocity. In addition, the NATIVE sequence was used with or without flow compensation. Vascular stenosis was quantitatively estimated by measurement of the signal intensities in non-contrast MRA images. MRA with NATIVE sequence demonstrated an accurate estimation of 30% vascular stenosis at slow flow velocity. However, 30% stenosis was overestimated in cases of high flow velocity. Estimation was improved by using a flow compensation sequence. 70% stenosis was overestimated on MRA with NATIVE sequence. Estimation of 70% stenosis was improved by using a flow compensation sequence. Accurate estimation of vascular stenosis in MRA with a NATIVE sequence is improved by using the flow compensation technique. MRA with NATIVE sequence is considered to

  18. Probing single magnon excitations in Sr2IrO4 using O K-edge resonant inelastic x-ray scattering

    International Nuclear Information System (INIS)

    Liu, X; Ding, H; Dean, M P M; Yin, W G; Hill, J P; Liu, J; Ramesh, R; Chiuzbăian, S G; Jaouen, N; Nicolaou, A; Serrao, C Rayan

    2015-01-01

    Resonant inelastic x-ray scattering (RIXS) at the L-edge of transition metal elements is now commonly used to probe single magnon excitations. Here we show that single magnon excitations can also be measured with RIXS at the K-edge of the surrounding ligand atoms when the center heavy metal elements have strong spin–orbit coupling. This is demonstrated with oxygen K-edge RIXS experiments on the perovskite Sr 2 IrO 4 , where low energy peaks from single magnon excitations were observed. This new application of RIXS has excellent potential to be applied to a wide range of magnetic systems based on heavy elements, for which the L-edge RIXS energy resolution in the hard x-ray region is usually poor. (fast track communication)

  19. Optical properties of boron carbide near the boron K edge evaluated by soft-x-ray reflectometry from a Ru/B4C multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Ksenzov, Dmitriy; Panzner, Tobias; Schlemper, Christoph; Morawe, Christian; Pietsch, Ullrich

    2009-12-10

    Soft-x-ray Bragg reflection from two Ru/B4C multilayers with 10 and 63 periods was used for independent determination of both real and imaginary parts of the refractive index n = 1 -{delta} + i{beta} close to the boron K edge ({approx}188 eV). Prior to soft x-ray measurements, the structural parameters of the multilayers were determined by x-ray reflectometry using hard x rays. For the 63-period sample, the optical properties based on the predictions made for elemental boron major deviations were found close to the K edge of boron for the 10-period sample explained by chemical bonding of boron to B4C and various boron oxides.

  20. User's guide for the portable microprocessor equipment: 'KfK K-edge densitometer' for quantitative determination of Th, U, Np, Pu, Am in solutions

    International Nuclear Information System (INIS)

    Michel-Piper, I.; Matussek, P.

    1985-06-01

    This report describes the hardware and software features, and the use of the microprocessor-controlled multichannel analyzer system SILENA + IRIS. The self-contained portable system, which permits independent accumulation and evaluation of spectral data from the KfK K-edge densitometer, provides one of the possible means for the authentication of resident instruments by safeguards inspectors. The 'K-Edge' program, written in PL/M language for compatibility with the system's firmware, allows fully automated assays of heavy element concentrations in solutions by means of X-ray absorption edge spectrometry. It is primarily intended for highly accurate determinations of the U and Pu content in process- and product solutions of a reprocessing plant. (orig.)

  1. Sn-L3 EDGE and Fe K edge XANES spectra of the surface layer of ancient Chinese black mirror Heiqigu

    International Nuclear Information System (INIS)

    Gaowei Mengjia; Liu Yuzhen; Chu Wangsheng; Wu Ziyu; Wang Changsui

    2009-01-01

    The Chinese ancient black mirror known as Heiqigu was studied by x-ray-absorption near-edge structure spectroscopy and results were reported. The Sn-L 3 edge and Fe K edge spectra further confirmed the Schottky-type defect model in the Heiqigu surface system. And it was suggested that the surface layer of the mirror was a combined structure of oxidation of Sn(IV) and Sn(II). (authors)

  2. Mn K-edge XANES spectroscopy of photosynthetic water oxidation enzyme in the S0-, S1-, S2- and S3-states induced by flash excitation

    International Nuclear Information System (INIS)

    Ono, Taka-aki; Noguchi, Takumi; Inoue, Yorinao; Kusunoki, Masami; Matsushita, Tadashi; Oyanagi, Hiroyuki.

    1993-01-01

    Electronic and structural rearrangement of the Mn-cluster during the four step oxidation of water in photosynthetic oxygen evolution was studied by XANES spectroscopy. The Mn K-edge energy of the spectrum was changed with flash number to show a clear quadruple oscillation, indicating a periodic change in oxidation and electronic state of the Mn-cluster depending on Joliot and Kok's oxygen clock. (author)

  3. Magnetic resonance angiography for the head and neck region

    International Nuclear Information System (INIS)

    Aschenbach, R.; Esser, D.

    2004-01-01

    Magnetic resonance angiography is a noninvasive method in vascular imaging using noncontrast- enhanced and contrast-enhanced techniques. The contrast media used in contrast- enhanced magnetic resonance angiography are different from the X-ray contrast media and do not affect the thyroid gland or renal function. In detecting hypervascularized lesions in the head and neck, contrast-enhanced magnetic resonance angiography is the method of choice, which provides an acceptable quality in comparison to digital subtraction angiography. Future developments in magnetic resonance imaging techniques will cause a wider use of magnetic resonance angiography, especially in head and neck imaging. Digital subtraction angiography should therefore only be used in problem cases and for preoperative embolization [de

  4. Determining metal ion distributions using resonant scattering at very high-energy K-edges: Bi/Pb in Pb5Bi6Se14

    International Nuclear Information System (INIS)

    Zhang Yuegang; Lee, P.L.; Shastri, S.D.; Shu Deming; Wilkinson, A.P.; Chung Duck-Young; Kanatzidis, M.G.

    2005-01-01

    Powder diffraction data collected at ∝ 86 keV, and just below both the Pb and the Bi K-edges, on an imaging plate detector using synchrotron radiation from the Advanced Photon Source have been used to examine the Pb/Bi distribution over the 11 crystallographically distinct sites in Pb 5 Bi 6 Se 14 [space group P2 1 /m, a=16.0096(2) Aa, b=4.20148(4) Aa, c=21.5689(3) Aa and β=97.537(1) 0 ]. The scattering factors needed for the analyses were determined both by Kramers- Kronig transformation of absorption spectra and by analyses of diffraction patterns from reference compounds. Even with the relatively low scattering contrast that is available at the K-edges, it was possible to determine the Pb/Bi distribution and probe the presence of cation site vacancies in the material. The current results indicate that resonant scattering measurements at high-energy K-edges are a viable, and perhaps preferable, route to site occupancies when absorption from the sample or sample environment/container is a major barrier to the acquisition of high-quality resonant scattering data at lower-energy edges

  5. Performance of computed tomography for contrast agent concentration measurements with monochromatic x-ray beams: comparison of K-edge versus temporal subtraction

    International Nuclear Information System (INIS)

    Elleaume, H.; Charvet, A.M.; Corde, S.; Esteve, F.; Le Bas, J.F.

    2002-01-01

    We investigated the performance of monochromatic computed tomography for the quantification of contrast agent concentrations. Two subtraction methods (K-edge subtraction and temporal subtraction) were evaluated and compared theoretically and experimentally in terms of detection limit, precision and accuracy. Measurements were performed using synchrotron x-rays with Lucite phantoms (10 cm and 17.5 cm in diameter) containing iodine or gadolinium solutions ranging from 50 μg ml -1 to 5 mg ml -1 . The experiments were carried out using monochromators developed at the European Synchrotron Radiation Facility (ESRF) medical beamline. The phantoms were imaged either above and below the contrast agent K-edge, or before and after the addition of the contrast agent. Both methods gave comparable performance for phantoms less than 10 cm in diameter. For large phantoms, equivalent to a human head, the temporal subtraction is more suitable for detecting elements such as iodine, keeping a reasonable x-ray dose delivered to the phantom. A good agreement was obtained between analytical calculations, simulations and measurements. The beam harmonic content was taken into account in the simulations. It explains the performance degradation with high contrast agent concentrations. The temporal subtraction technique has the advantage of energy tunability and is well suited for imaging elements, such as iodine or gadolinium, in highly absorbing samples. For technical reasons, the K-edge method is preferable when the imaged organ is moving since the two measurements can be performed simultaneously, which is mandatory for obtaining a good subtraction. (author)

  6. Vibrationally resolved NEXAFS at C and N K-edges of pyridine, 2-fluoropyridine and 2,6-difluoropyridine: A combined experimental and theoretical assessment

    Energy Technology Data Exchange (ETDEWEB)

    Baiardi, Alberto; Mendolicchio, Marco; Barone, Vincenzo, E-mail: vincenzo.barone@sns.it [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56125 Pisa (Italy); Fronzoni, Giovanna; Cardenas Jimenez, Gustavo Adolfo; Stener, Mauro; Grazioli, Cesare [Dipartimento di Scienze Chimiche e Farmaceutiche, Universita’ di Trieste, Via Giorgieri 1, 34127 Trieste (Italy); Simone, Monica de [CNR-IOM, Laboratorio TASC, Area Science Park Basovizza, 34149 Trieste (Italy); Coreno, Marcello [CNR-ISM, UOS Trieste, Area Science Park Basovizza, 34149 Trieste (Italy)

    2015-11-28

    In the present work, the near edge X-ray absorption spectroscopy (NEXAFS) spectra at both C and N K-edges of pyridine, 2-fluoropyridine, and 2,6-difluoropyridine have been studied both experimentally and theoretically. From an electronic point of view, both transition potential density functional theory and time-dependent density functional theory approaches lead to reliable results provided that suitable basis sets and density functionals are employed. In this connection, the global hybrid B3LYP functional in conjunction with the EPR-III basis set appears particularly suitable after constant scaling of the band positions. For the N K-edge, vertical energies obtained at these levels and broadened by symmetric Gaussian distributions provide spectra in reasonable agreement with the experiment. Vibronic contributions further modulate the band-shapes leading to a better agreement with the experimental results, but are not strictly necessary for semi-quantitative investigations. On the other hand, vibronic contributions are responsible for strong intensity redistribution in the NEXAFS C K-edge spectra, and their inclusion is thus mandatory for a proper description of experiments. In this connection, the simple vertical gradient model is particularly appealing in view of its sufficient reliability and low computational cost. For more quantitative results, the more refined vertical Hessian approach can be employed, and its effectiveness has been improved thanks to a new least-squares fitting approach.

  7. Metal and ligand K-edge XAS of organotitanium complexes: metal 4p and 3d contributions to pre-edge intensity and their contributions to bonding.

    Science.gov (United States)

    George, Serena DeBeer; Brant, Patrick; Solomon, Edward I

    2005-01-19

    Titanium cyclopentadienyl (Cp) complexes play important roles as homogeneous polymerization catalysts and have recently received attention as potential anticancer agents. To systematically probe the contribution of the Cp to bonding in organotitanium complexes, Ti K-edge XAS has been applied to TiCl(4) and then to the mono- and bis-Cp complexes, TiCpCl(3) and TiCp(2)Cl(2). Ti K-edge XAS is used as a direct probe of metal 3d-4p mixing and provides insight into the contribution of the Cp to bonding. These data are complimented by Cl K-edge XAS data, which provide a direct probe of the effect of the Cp on the bonding to the spectator chloride ligand. The experimental results are correlated to DFT calculations. A model for metal 3d-4p mixing is proposed, which is based on covalent interactions with the ligands and demonstrates that metal K-pre-edge intensities may be used as a measure of ligand-metal covalency in molecular Ti(IV) systems in noncentrosymmetric environments.

  8. In situ removal of carbon contamination from a chromium-coated mirror: ideal optics to suppress higher-order harmonics in the carbon K-edge region.

    Science.gov (United States)

    Toyoshima, Akio; Kikuchi, Takashi; Tanaka, Hirokazu; Mase, Kazuhiko; Amemiya, Kenta

    2015-11-01

    Carbon-free chromium-coated optics are ideal in the carbon K-edge region (280-330 eV) because the reflectivity of first-order light is larger than that of gold-coated optics while the second-order harmonics (560-660 eV) are significantly suppressed by chromium L-edge and oxygen K-edge absorption. Here, chromium-, gold- and nickel-coated mirrors have been adopted in the vacuum ultraviolet and soft X-ray branch beamline BL-13B at the Photon Factory in Tsukuba, Japan. Carbon contamination on the chromium-coated mirror was almost completely removed by exposure to oxygen at a pressure of 8 × 10(-2) Pa for 1 h under irradiation of non-monochromated synchrotron radiation. The pressure in the chamber recovered to the order of 10(-7) Pa within a few hours. The reflectivity of the chromium-coated mirror of the second-order harmonics in the carbon K-edge region (560-660 eV) was found to be a factor of 0.1-0.48 smaller than that of the gold-coated mirror.

  9. Comparison of Power Versus Manual Injection in Bolus Shape and Image Quality on Contrast-Enhanced Magnetic Resonance Angiography: An Experimental Study in a Swine Model.

    Science.gov (United States)

    Tsuboyama, Takahiro; Jost, Gregor; Pietsch, Hubertus; Tomiyama, Noriyuki

    2017-09-01

    The aim of this study was to compare power versus manual injection in bolus shape and image quality on contrast-enhanced magnetic resonance angiography (CE-MRA). Three types of CE-MRA (head-neck 3-dimensional [3D] MRA with a test-bolus technique, thoracic-abdominal 3D MRA with a bolus-tracking technique, and thoracic-abdominal time-resolved 4-dimensional [4D] MRA) were performed after power and manual injection of gadobutrol (0.1 mmol/kg) at 2 mL/s in 12 pigs (6 sets of power and manual injections for each type of CE-MRA). For the quantitative analysis, the signal-to-noise ratio was measured on ascending aorta, descending aorta, brachiocephalic trunk, common carotid artery, and external carotid artery on the 6 sets of head-neck 3D MRA, and on ascending aorta, descending aorta, brachiocephalic trunk, abdominal aorta, celiac trunk, and renal artery on the 6 sets of thoracic-abdominal 3D MRA. Bolus shapes were evaluated on the 6 sets each of test-bolus scans and 4D MRA. For the qualitative analysis, arterial enhancement, superimposition of nontargeted enhancement, and overall image quality were evaluated on 3D MRA. Visibility of bolus transition was assessed on 4D MRA. Intraindividual comparison between power and manual injection was made by paired t test, Wilcoxon rank sum test, and analysis of variance by ranks. Signal-to-noise ratio on 3D MRA was statistically higher with power injection than with manual injection (P < 0.001). Bolus shapes (test-bolus, 4D MRA) were represented by a characteristic standard bolus curve (sharp first-pass peak followed by a gentle recirculation peak) in all the 12 scans with power injection, but only in 1 of the 12 scans with manual injection. Standard deviations of time-to-peak enhancement were smaller in power injection than in manual injection. Qualitatively, although both injection methods achieved diagnostic quality on 3D MRA, power injection exhibited significantly higher image quality than manual injection (P = 0.001) due to

  10. High-resolution blood-pool-contrast-enhanced MR angiography in glioblastoma: tumor-associated neovascularization as a biomarker for patient survival. A preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Puig, Josep; Blasco, Gerard; Remollo, Sebastian; Hernandez, David; Pedraza, Salvador [Hospital Universitari Dr Josep Trueta, Research Unit of Diagnostic Imaging Institute (IDI), Department of Radiology [Girona Biomedical Research Institute] IDIBGI, Girona (Spain); Daunis-i-Estadella, Josep; Mateu, Gloria [University of Girona, Department of Computer Science, Applied Mathematics and Statistics, Girona (Spain); Alberich-Bayarri, Angel [La Fe Polytechnics and University Hospital, Biomedical Imaging Research Group (GIBI230), La Fe Health Research Institute, Valencia (Spain); Essig, Marco [University of Manitoba, Department of Radiology, Winnipeg (Canada); Jain, Rajan [NYU School of Medicine, Division of Neuroradiology, Department of Radiology, New York, NY (United States); Puigdemont, Montserrat [Hospital Universitari Dr Josep Trueta, Catalan Institute of Oncology (ICO), Hospital Cancer Registry, Girona (Spain); Sanchez-Gonzalez, Javier [Philips Healthcare Iberica, Madrid (Spain); Wintermark, Max [Stanford University, Department of Radiology, Neuroradiology Division, Palo Alto, CA (United States)

    2016-01-15

    The objective of the study was to determine whether tumor-associated neovascularization on high-resolution gadofosveset-enhanced magnetic resonance angiography (MRA) is a useful biomarker for predicting survival in patients with newly diagnosed glioblastomas. Before treatment, 35 patients (25 men; mean age, 64 ± 14 years) with glioblastoma underwent MRI including first-pass dynamic susceptibility contrast (DSC) perfusion and post-contrast T1WI sequences with gadobutrol (0.1 mmol/kg) and, 48 h later, high-resolution MRA with gadofosveset (0.03 mmol/kg). Volumes of interest for contrast-enhancing lesion (CEL), non-CEL, and contralateral normal-appearing white matter were obtained, and DSC perfusion and DWI parameters were evaluated. Prognostic factors were assessed by Kaplan-Meier survival and Cox proportional hazards model. Eighteen (51.42 %) glioblastomas were hypervascular on high-resolution MRA. Hypervascular glioblastomas were associated with higher CEL volume and lower Karnofsky score. Median survival rates for patients with hypovascular and hypervascular glioblastomas treated with surgery, radiotherapy, and chemotherapy were 15 and 9.75 months, respectively (P < 0.001). Tumor-associated neovascularization was the best predictor of survival at 5.25 months (AUC = 0.794, 81.2 % sensitivity, 77.8 % specificity, 76.5 % positive predictive value, 82.4 % negative predictive value) and yielded the highest hazard ratio (P < 0.001). Tumor-associated neovascularization detected on high-resolution blood-pool-contrast-enhanced MRA of newly diagnosed glioblastoma seems to be a useful biomarker that correlates with worse survival. (orig.)

  11. Contrast-enhanced magnetic resonance angiography for the detection of crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with operative findings

    Energy Technology Data Exchange (ETDEWEB)

    Calder, Alistair D.; Hiorns, Melanie P.; Olsen, Oystein E. [Hospital for Children NHS Trust, Department of Radiology, London (United Kingdom); Abhyankar, Aruna; Mushtaq, Imran [Hospital for Children NHS Trust, Department of Urology, London (United Kingdom)

    2007-04-15

    Crossing renal vessels (CRV) are associated with ureteropelvic junction (UPJ) obstruction, particularly when presentation is beyond the neonatal period. Their presence may influence surgical management. To evaluate the accuracy of contrast-enhanced magnetic resonance angiography (CE-MRA) in the identification of CRV in children requiring surgical treatment of symptomatic UPJ obstruction, against a gold standard of laparoscopic or open surgical findings. We reviewed CE-MRA studies (3-D T2-weighted turbo spin-echo and multiphase 3-D spoiled gradient echo following intravenous gadolinium administration) of 14 children, age range 6-15 years, performed prior to surgery for suspected CRV-related UPJ obstruction. Consensus reviews of the CE-MRA studies were compared with surgical findings. CE-MRA demonstrated CRV at the level of the obstruction in nine and no crossing vessels in five children. These were all verified intraoperatively ({chi}{sup 2} = 14.0; P < 0.001). In eight of the nine patients with CRV there was no evidence of intrinsic obstruction at surgery. In the remaining patient there was fibrosis of the upper ureter. CE-MRA is an accurate means of identifying CRV in children older than 6 years with symptomatic UPJ obstruction. (orig.)

  12. Gadolinium-enhanced MR angiography (Gd-MRA) of thoracic vasculature in an animal model using double-dose gadolinium and quiet breathing

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, R.J.; Strouse, P.J. [Section of Pediatric Radiology, University of Michigan Health System, Ann Arbor (United States); Londy, F.J. [Dept. of Radiology, University of Michigan Hospitals, Ann Arbor, MI (United States); Wakefield, T.W. [Dept. of Surgery, Section of Vascular Surgery, University of Michigan Hospitals, Ann Arbor, MI (United States)

    2001-08-01

    Objective. To evaluate a gadolinium-enhanced MR angiography (Gd-MRA) imaging protocol for the assessment of thoracic vessels using double-dose gadolinium and quiet breathing. An animal model was used to simulate imaging in infants and young children. Material and methods. Six baboons (Papio anubis), mean weight 5.7 kg, were sedated and intubated. After the injection of double-dose Gd-DTPA (0.2 mmol/kg) through a peripheral vein, a coronal spoiled 3D gradient-echo volume acquisition was obtained during quiet breathing. Two radiologists reviewed the images for visualization of aortic arch, brachiocephalic vessel origins, pulmonary arteries (central, upper lobe and descending branches), and pulmonary veins (upper and lower). Results. Visualization was excellent for the aortic arch, brachiocephalic vessel origins, and pulmonary arteries, including the hilar branches. Visualization was excellent for the lower and right upper pulmonary veins and fair for the left upper pulmonary vein. There was excellent agreement between radiologists. Conclusion. Imaging of thoracic vessels with Gd-MRA using double gadolinium during quiet breathing was effective in our animal model. The advantages of this technique include a short imaging time and depiction of vascular segments - branches of pulmonary arteries and intraparenchymal segments of pulmonary veins - not optimally visualized with other non-invasive imaging techniques. (orig.)

  13. Gadolinium-enhanced MR angiography (Gd-MRA) of thoracic vasculature in an animal model using double-dose gadolinium and quiet breathing

    International Nuclear Information System (INIS)

    Hernandez, R.J.; Strouse, P.J.; Londy, F.J.; Wakefield, T.W.

    2001-01-01

    Objective. To evaluate a gadolinium-enhanced MR angiography (Gd-MRA) imaging protocol for the assessment of thoracic vessels using double-dose gadolinium and quiet breathing. An animal model was used to simulate imaging in infants and young children. Material and methods. Six baboons (Papio anubis), mean weight 5.7 kg, were sedated and intubated. After the injection of double-dose Gd-DTPA (0.2 mmol/kg) through a peripheral vein, a coronal spoiled 3D gradient-echo volume acquisition was obtained during quiet breathing. Two radiologists reviewed the images for visualization of aortic arch, brachiocephalic vessel origins, pulmonary arteries (central, upper lobe and descending branches), and pulmonary veins (upper and lower). Results. Visualization was excellent for the aortic arch, brachiocephalic vessel origins, and pulmonary arteries, including the hilar branches. Visualization was excellent for the lower and right upper pulmonary veins and fair for the left upper pulmonary vein. There was excellent agreement between radiologists. Conclusion. Imaging of thoracic vessels with Gd-MRA using double gadolinium during quiet breathing was effective in our animal model. The advantages of this technique include a short imaging time and depiction of vascular segments - branches of pulmonary arteries and intraparenchymal segments of pulmonary veins - not optimally visualized with other non-invasive imaging techniques. (orig.)

  14. Impact of ECG gating in contrast-enhanced MR angiography for the assessment of the pulmonary veins and the left atrium anatomy

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, M.; Buecker, A.; Muehlenbruch, G.; Guenther, R.W.; Spuentrup, E. [Klinik fuer Radiologische Diagnostik, Universitaetsklinikum RWTH Aachen (Germany); Schauerte, P. [Medizinische Klinik 1, Universitaetsklinikum RWTH Aachen (Germany)

    2006-02-15

    Purpose: Implementation of ECG gating in contrast-enhanced MR angiography (ceMRA) for improved visualization of the pulmonary veins, the left atrium, and the thoracic vessels. Materials and Methods: CeMRA was performed on twelve patients with a history of recurrent atrial fibrillation for the purpose of an intra-individual comparison with and without ECG gating on a 1.5 Tesla MR system (Gyroscan Intera, Philips Medical Systems, Best, NL). Objective image quality parameters such as the signal-to-noise ratio (SNR) of the blood and the contrast-to-noise ratio (CNR) between the blood and myocardium or lung parenchyma were analyzed. The contour sharpness of the pulmonary veins, left atrium, ascending aorta, and pulmonary trunk was also measured. In addition, the artifact level was subjectively assessed by two observers blinded with respect to the sequence parameters. Statistically significant differences (p<0.05) between the procedures were analyzed using the Wilcoxon test and Pearson Chi-square test. Results: The use of ECG gating in ceMRA significantly reduced artifacts caused by cardiac motion and vessel pulsation. This in turn lead to a significant increase in the contour sharpness of the left atrium and the thoracic vessels. In addition, higher SNR and CNR were found using ECG-gated ceMRA compared to standard ceMRA. Conclusion: The use of ECG gating in ceMRA results in artifact-free and sharper delineation of the structures of the heart and thoracic vessels. (orig.)

  15. Impact of ECG gating in contrast-enhanced MR angiography for the assessment of the pulmonary veins and the left atrium anatomy

    International Nuclear Information System (INIS)

    Katoh, M.; Buecker, A.; Muehlenbruch, G.; Guenther, R.W.; Spuentrup, E.; Schauerte, P.

    2006-01-01

    Purpose: Implementation of ECG gating in contrast-enhanced MR angiography (ceMRA) for improved visualization of the pulmonary veins, the left atrium, and the thoracic vessels. Materials and Methods: CeMRA was performed on twelve patients with a history of recurrent atrial fibrillation for the purpose of an intra-individual comparison with and without ECG gating on a 1.5 Tesla MR system (Gyroscan Intera, Philips Medical Systems, Best, NL). Objective image quality parameters such as the signal-to-noise ratio (SNR) of the blood and the contrast-to-noise ratio (CNR) between the blood and myocardium or lung parenchyma were analyzed. The contour sharpness of the pulmonary veins, left atrium, ascending aorta, and pulmonary trunk was also measured. In addition, the artifact level was subjectively assessed by two observers blinded with respect to the sequence parameters. Statistically significant differences (p<0.05) between the procedures were analyzed using the Wilcoxon test and Pearson Chi-square test. Results: The use of ECG gating in ceMRA significantly reduced artifacts caused by cardiac motion and vessel pulsation. This in turn lead to a significant increase in the contour sharpness of the left atrium and the thoracic vessels. In addition, higher SNR and CNR were found using ECG-gated ceMRA compared to standard ceMRA. Conclusion: The use of ECG gating in ceMRA results in artifact-free and sharper delineation of the structures of the heart and thoracic vessels. (orig.)

  16. Follow-up of intracranial aneurysms treated by a WEB flow disrupter: a comparative study of DSA and contrast-enhanced MR angiography.

    Science.gov (United States)

    Mine, Benjamin; Tancredi, Illario; Aljishi, Ali; Alghamdi, Faisal; Beltran, Margarita; Herchuelz, Maxime; Lubicz, Boris

    2016-06-01

    To compare contrast-enhanced MR angiography (CE-MRA) and DSA for the follow-up of intracranial aneurysms (IAs) treated with the Woven EndoBridge embolization system DL (WEB DL; Sequent Medical, Aliso Viejo, California, USA). We retrospectively identified all patients treated with a WEB DL between November 2010 and February 2013 in 2 hospitals. The IA occlusion was graded on follow-up CE-MRA and DSA by 4 independent readers and by 2 readers reaching a consensus, respectively. Interobserver agreement for MRA and intertechnique agreement was evaluated by calculating linear weighted κ. Fifteen patients with 16 IAs were included. Mean delay between MRA and DSA was 2 months (range 0-16 months). Interobserver agreement for MRA was substantial to almost perfect (κ=0.686-0.921; mean κ=0.809). Intertechnique agreement was moderate to substantial (κ=0.579-0.724; mean κ=0.669). Only three out of five inadequately occluded IAs were detected by MRA. CE-MRA is a useful tool for the follow-up of IAs treated with a WEB DL. However, early follow-up with DSA remains mandatory to detect inadequately occluded IAs. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  17. String-like lumen in below-the-knee chronic total occlusions on contrast-enhanced magnetic resonance angiography predicts intraluminal recanalization and better blood flow restoration

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yue-Qi; Lu, Hai-Tao; Wei, Li-Ming; Cheng, Ying-Sheng; Wang, Jian-Bo; Zhao, Jun-Gong [Shanghai Jiao Tong University Affiliated Sixth People' s Hospital, Department of Diagnostic and Interventional Radiology, Shanghai (China); Liu, Fang [Shanghai Jiao Tong University Affiliated Sixth People' s Hospital, Department of Endocrinology, Shanghai (China)

    2017-07-15

    To determine whether string-like lumina (SLs) on contrast-enhanced magnetic resonance angiography (CE-MRA) predict better outcomes in diabetic patients with below-the-knee (BTK) chronic total occlusions (CTOs). This study involved 317 long-segment (>5 cm) BTK CTOs of 245 patients that were examined using CE-MRA and treated using endovascular angioplasty. An SL with a CTO was slowly filled with blood on conventional CE-MRA. Univariate and multivariate analyses were performed to identify predictors of procedural success, recanalisation method and immediate blood flow restoration. The target-lesion patency and limb-salvage rates were assessed. SL-positive CTOs (n = 60) achieved a higher technique success rate, preferred intraluminal angioplasty and better blood flow restoration than SL-negative CTOs (n = 257, P < 0.05). Multivariate analyses revealed that lesion length was the independent predictor of procedural success (P = 0.028). SL was a predictor of intraluminal angioplasty (P < 0.001) and good blood-flow restoration (P = 0.004). Kaplan-Meier analyses at 12 months revealed a higher target lesion patency rate (P = 0.04) and limb-salvage rate (P = 0.35) in SL-positive CTOs. In patients with BTK CTOs, SL predicted intraluminal angioplasty and good blood-flow restoration for BTK CTOs. (orig.)

  18. Diagnostic accuracy of C-arm CT during selective transcatheter angiography for hepatocellular carcinoma: comparison with intravenous contrast-enhanced, biphasic, dynamic MDCT

    Energy Technology Data Exchange (ETDEWEB)

    Higashihara, Hiroki; Osuga, Keigo; Onishi, Hiromitsu; Nakamoto, Atsushi; Tsuboyama, Takahiro; Maeda, Noboru; Hori, Masatoshi; Kim, Tonsok; Tomiyama, Noriyuki [Osaka University Graduate School of Medicine, Department of Diagnostic and Interventional Radiology, Suita, Osaka (Japan)

    2012-04-15

    This study was aimed to compare the accuracy, sensitivity, and positive predictive value of C-arm CT (CACT) during selective transcatheter angiography with those of multidetector CT (MDCT) in the detection of hepatocellular carcinoma (HCC). In this prospective study, 30 patients (mean age, 73 years) with unresectable HCC were examined with CACT before chemoembolisation. Images of a combination of CACT during arterial portography (CACTAP) and dual-phase CACT during hepatic arteriography (CACTHA) was obtained and images of intravenous contrast-enhanced, biphasic, dynamic, MDCT was also obtained beforehand. Three blinded observers independently reviewed CACT and MDCT. Diagnostic accuracy was evaluated by the alternative free-response receiver operating characteristic (AFROC) method. Sensitivities and positive predictive values (PPV) were analyzed with the paired t-test. In the mean area under the AFROC curve (Az), there was no significant difference between MDCT and CACT (MDCT, mean Az value, 0.83; CACT, 0.85, respectively) (P = 0.32). There was also no significant difference between the two techniques in sensitivity (MDCT, mean 0.65; CACT, 0.60) and PPV (MDCT, mean 0.98; CACT, 0.97) (P = 0.40, P = 0.68, respectively). The diagnostic accuracy of CACT was equivalent to that of biphasic CT in the diagnosis of HCC. (orig.)

  19. Contrast-enhanced magnetic resonance angiography for the detection of crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with operative findings

    International Nuclear Information System (INIS)

    Calder, Alistair D.; Hiorns, Melanie P.; Olsen, Oystein E.; Abhyankar, Aruna; Mushtaq, Imran

    2007-01-01

    Crossing renal vessels (CRV) are associated with ureteropelvic junction (UPJ) obstruction, particularly when presentation is beyond the neonatal period. Their presence may influence surgical management. To evaluate the accuracy of contrast-enhanced magnetic resonance angiography (CE-MRA) in the identification of CRV in children requiring surgical treatment of symptomatic UPJ obstruction, against a gold standard of laparoscopic or open surgical findings. We reviewed CE-MRA studies (3-D T2-weighted turbo spin-echo and multiphase 3-D spoiled gradient echo following intravenous gadolinium administration) of 14 children, age range 6-15 years, performed prior to surgery for suspected CRV-related UPJ obstruction. Consensus reviews of the CE-MRA studies were compared with surgical findings. CE-MRA demonstrated CRV at the level of the obstruction in nine and no crossing vessels in five children. These were all verified intraoperatively (χ 2 = 14.0; P < 0.001). In eight of the nine patients with CRV there was no evidence of intrinsic obstruction at surgery. In the remaining patient there was fibrosis of the upper ureter. CE-MRA is an accurate means of identifying CRV in children older than 6 years with symptomatic UPJ obstruction. (orig.)

  20. Contrast-enhanced computed tomography angiography and volume-rendered imaging for evaluation of cellophane banding in a dog with extrahepatic portosystemic shunt

    Directory of Open Access Journals (Sweden)

    H. Yoon

    2011-04-01

    Full Text Available A 4-year-old, 1.8 kg, male, castrated Maltese was presented for evaluation of urolithiasis. Urinary calculi were composed of ammonium biurate. Preprandial and postprandial bile acids were 44.2 and 187.3 μmol/ , respectively (reference ranges 0–10 and 0–20 μmol/ , respectively. Single-phase contrast-enhanced computed tomography angiography (CTA with volume-rendered imaging (VRI was obtained. VRI revealed a portocaval shunt originating just cranial to a tributary of the gastroduodenal vein and draining into the caudal vena cava at the level of the epiploic foramen. CTA revealed a 3.66 mm-diameter shunt measured at the level of the termination of the shunt and a 3.79 mm-diameter portal vein measured at the level between the origin of the shunt and the porta of the liver. Surgery was performed using cellophane banding without attenuation. Follow-up single-phase CTA with VRI was obtained 10 weeks after surgery. VRI revealed no evidence of portosystemic communication on the level of a cellophane band and caudal to the cellophane band. CTA demonstrated an increased portal vein diameter (3.79–5.27 mm measured at the level between the origin of the shunt and the porta of the liver. Preprandial and postprandial bile acids were 25 and 12.5 μmol/ , respectively (aforementioned respective reference ranges, 3 months post-surgery. No problems were evident at 6 months.

  1. The benefit of non contrast-enhanced magnetic resonance angiography for predicting vascular access surgery outcome : a coomputer model perspective

    NARCIS (Netherlands)

    Merkx, M.A.G.; Huberts, W.; Bosboom, E.M.H.; Bode, A.S.; Bescos, J.O.; Tordoir, J.H.M.; Breeuwer, M.; Vosse, van de F.N.

    2013-01-01

    Introduction Vascular access (VA) surgery, a prerequisite for hemodialysis treatment of end-stage renal-disease (ESRD) patients, is hampered by complication rates, which are frequently related to flow enhancement. To assist in VA surgery planning, a patient-specific computer model for postoperative

  2. 3D Whole-Heart Coronary MR Angiography at 1.5T in Healthy Volunteers: Comparison between Unenhanced SSFP and Gd-Enhanced FLASH Sequences

    International Nuclear Information System (INIS)

    Gweon, Hye Mi; Kim, Sang Jin; Lee, Sang Min; Hong, Yoo Jin; Kim, Tae Hoon

    2011-01-01

    To validate the optimal cardiac phase and appropriate acquisition window for three-dimensional (3D) whole-heart coronary magnetic resonance angiography (MRA) with a steady-state free precession (SSFP) sequence, and to compare image quality between SSFP and Gd-enhanced fast low-angle shot (FLASH) MR techniques at 1.5 Tesla (T). Thirty healthy volunteers (M:F 25:5; mean age, 35 years; range, 24-54 years) underwent a coronary MRA at 1.5T. 3D whole-heart coronary MRA with an SSFP was performed at three different times: 1) at end-systole with a narrow (120-msec) acquisition window (ESN), 2) mid-diastole with narrow acquisition (MDN); and 3) mid-diastole with wide (170-msec) acquisition (MDW). All volunteers underwent a contrast enhanced coronary MRA after undergoing an unenhanced 3D true fast imaging with steady-state precession (FISP) MRA three times. A contrast enhanced coronary MRA with FLASH was performed during MDN. Visibility of the coronary artery and image quality were evaluated for 11 segments, as suggested by the American Heart Association. Image quality was scored by a five-point scale (1 = not visible to 5 = excellent). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were evaluated at the proximal coronary arteries. The SSFP sequence rendered higher visibility coronary segments, higher image quality, as well as higher SNR and CNR than the Gd-enhanced FLASH technique at 1.5T (p < 0.05). The visibility of coronary segments, image quality, SNR and CNR in the ESN, MDN and MDW with SSFP sequence did not differ significantly. An SSFP sequence provides an excellent method for the 3D whole-heart coronary MRA at 1.5T. Contrast enhanced coronary MRA using the FLASH sequence does not help improve the visibility of coronary segments, image quality, SNR or CNR on the 3D whole-heart coronary MRA.

  3. Non-enhanced 3D MR angiography of the lower extremity using ECG-gated TSE imaging with non-selective refocusing pulses. Initial experience

    International Nuclear Information System (INIS)

    Lanzman, R.S.; Blondin, D.; Orzechowski, D.; Scherer, A.; Moedder, U.; Kroepil, P.; Godehardt, E.

    2010-01-01

    Purpose: To evaluate non-enhanced 3D MR angiography using turbo spin echo (TSE) imaging with non-selective refocusing pulses (NATIVE SPACE MRA) for the visualization of the arteries of the lower extremity. Materials and Methods: Three-station imaging (iliac arteries, femoral arteries, arteries of the lower leg) was performed in 8 healthy volunteers and 3 patients with peripheral artery disease (PAD) using a 1.5 T MR scanner. In 8 healthy volunteers, 4 different acquisition schemes were performed with the following imaging parameters: S 1: acquisition with every heartbeat (RR = 1), spoiler gradient of 25 % (SG = 25 %); S 2: RR = 1, SG = 0 %; S 3: RR = 2, SG = 25 %; S 4: RR = 2, SG = 0 %. The subjective image quality on a 4-point-scale (4 = excellent to 1 = not diagnostic) and relative SNR were assessed. In 3 patients with peripheral artery disease (PAD), SPACE MRA was performed for assessment of stenosis. Results: The mean subjective image quality was significantly lower for the iliac arteries compared to the femoral arteries and arteries of the lower leg (p < 0.0001). The subjective image quality for acquisition scheme S 1 was significantly lower than the image quality for S 3 and S 4 for the iliac arteries (p < 0.01), while the subjective image quality for acquisition scheme S 2 was significantly lower than S 3 and S 4 for the femoral arteries and the arteries of the lower leg (p < 0.01). The relative SNR was significantly higher for acquisition schemes S 3 and S 4 as compared to S 1 and S 2 (p < 0.0001) for all regions. SPACE MRA disclosed 7 significant stenoses in 3 PAD patients. Conclusion: ECG-gated SPACE MRA is a promising imaging technique for non-enhanced assessment of the arteries of the lower extremity. (orig.)

  4. Utilizing generalized autocalibrating partial parallel acquisition (GRAPPA) to achieve high-resolution contrast-enhanced MR angiography of hepatic artery: Initial experience in orthotopic liver transplantation candidates

    Energy Technology Data Exchange (ETDEWEB)

    Xu Pengju [Department of Radiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai (China)]. E-mail: xpjbfc@163.com; Yan Fuhua [Department of Radiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai (China)]. E-mail: yanfuhua@yahoo.com; Wang Jianhua [Department of Radiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai (China); Lin Jiang [Department of Radiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai (China); Fan Jia [Liver Cancer Institute, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai (China)

    2007-03-15

    Objective: To evaluate feasibility of using GRAPPA to acquire high-resolution 3D contrast-enhanced MR angiography (CE-MRA) of hepatic artery and value of GRAPPA for displaying vessels anatomy. Materials and methods: High-resolution CE-MRA using GRAPPA was performed in 67 orthotopic liver transplantation recipient candidates. Signal intensity (SI) and relative SI, i.e., Cv-ro (vessel-to-liver contrast) of the aorta and the hepatic common artery (HCA), were measured. The SI and the relative SI were compared and analyzed using T-test. For purpose of qualitative evaluation, the vessel visualization quality and the order of depicted hepatic artery branches were evaluated by two radiologists independently and assessed by weighted kappa analysis. The depiction of hepatic arterial anatomy and variations was evaluated, and results were correlated with the findings in surgery. Results: The mean SI values were 283.29 {+-} 65.07 (mean {+-} S.D.) for aorta and 283.16 {+-} 64.07 for HCA, respectively. The mean relative SI values were 0.698 {+-} 0.09 for aorta and 0.696 {+-} 0.09 for HCA, respectively. Homogeneous enhancement between aorta and HCA was confirmed by statistically insignificant differences (p-values were 0.89 for mean SI values and 0.12 for mean relative SI values, respectively). The average score for vessel visualization ranged from good to excellent for different artery segments. Overall interobserver agreement in the visualization of different artery segments was excellent (kappa value > 0.80). The distal intrahepatic segmental arteries were well delineated for majority of patients with excellent interobserver agreement. Normal hepatic arterial anatomy was correctly demonstrated in 53 patients, and arterial anomalies were accurately detected on high-resolution MRA image of all 14 patients. Conclusion: High-resolution hepatic artery MRA acquired using GRAPPA in a reproducible manner excellently depicts and delineates small vessels and can be routinely used for

  5. Non-enhanced magnetic resonance imaging of unruptured intracranial aneurysms at 7 Tesla: Comparison with digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Wrede, Karsten H.; Chen, Bixia [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); University Hospital Essen, Department of Neurosurgery, Essen (Germany); Matsushige, Toshinori [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); University Hospital Essen, Department of Neurosurgery, Essen (Germany); Hiroshima University, Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima (Japan); Goericke, Sophia L.; Umutlu, Lale; Forsting, Michael [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Quick, Harald H. [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); University Hospital Essen, High Field and Hybrid MR Imaging, Essen (Germany); Ladd, Mark E. [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); German Cancer Research Center (DKFZ), Division of Medical Physics in Radiology (E020), Heidelberg (Germany); Johst, Soeren [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); Sure, Ulrich [University Hospital Essen, Department of Neurosurgery, Essen (Germany); Schlamann, Marc [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); University Hospital Giessen, Department of Neuroradiology, Giessen (Germany)

    2017-01-15

    To prospectively evaluate non-contrast-enhanced 7-Tesla (T) MRA for delineation of unruptured intracranial aneurysms (UIAs) in comparison with DSA. Forty patients with single or multiple UIAs were enrolled in this IRB-approved trial. Sequences acquired at 7 T were TOF MRA and non-contrast-enhanced MPRAGE. All patients additionally underwent 3D rotational DSA. Two neuroradiologists individually analysed the following aneurysm and image features on a five-point scale in 2D and 3D image reconstructions: delineation of parent vessel, dome and neck; overall image quality; presence of artefacts. Interobserver accordance was assessed by the kappa coefficient. A total of 64 UIAs were detected in DSA and in all 2D and 3D MRA image reconstructions. Ratings showed comparable results for DSA and 7-T MRA when considering all image reconstructions. Highest ratings for individual image reconstructions were given for 2D MPRAGE and 3D TOF MRA. Interobserver accordance was almost perfect for the majority of ratings. This study demonstrates excellent delineation of UIAs using 7-T MRA within a clinical setting comparable to the gold standard, DSA. The combination of 7-T non-enhanced MPRAGE and TOF MRA for assessment of untreated UIAs is a promising clinical application of ultra-high-field MRA. (orig.)

  6. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    International Nuclear Information System (INIS)

    Sun, Hao; Hou, Xin-Yi; Xue, Hua-Dan; Li, Xiao-Guang; Jin, Zheng-Yu; Qian, Jia-Ming; Yu, Jian-Chun; Zhu, Hua-Dong

    2015-01-01

    Highlights: • GIB is a common gastrointestinal emergency with a high mortality rate. • Detection and localization of GIB source are important for imaging modality. • DSDECTA using a dual-phase scan protocol is clinically feasible. • DSDECTA with VNE and iodine map images can diagnose the active GIB source accurately. • DSDECTA can reduce radiation dose compared with conventional CT examination in GIB. - Abstract: Objectives: To evaluate the clinical feasibility of dual-source dual-energy CT angiography (DSDECTA) with virtual non-enhanced images and iodine map for active gastrointestinal bleeding (GIB). Methods: From June 2010 to December 2012, 112 consecutive patients with clinical signs of active GIB underwent DSDECTA with true non-enhanced (TNE), arterial phase with single-source mode, and portal-venous phase with dual-energy mode (100 kVp/230 mAs and Sn 140 kVp/178 mAs). Virtual non-enhanced CT (VNE) image sets and iodine map were reformatted from ‘Liver VNC’ software. The mean CT number, noise, signal to noise ratio (SNR), image quality and radiation dose were compared between TNE and VNE image sets. Two radiologists, blinded to clinical data, interpreted images from DSDECTA with TNE (protocol 1), and DSDECTA with VNE and iodine map (protocol 2) respectively, with discordant interpretation resolved by consensus. The standards of reference included digital subtraction angiography, endoscopy, surgery, or final pathology reports. Receiver–operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) calculated for CT protocols 1 and 2, respectively. Results: There was no significant difference in mean CT numbers of all organs (including liver, pancreas, spleen, kidney, abdominal aorta, and psoas muscle) (P > 0.05). Lower noise and higher SNR were found on VNE images than TNE images (P < 0.05). Image quality of VNE was lower than that of TNE without significant difference (P > 0.05). The active GIB source was identified

  7. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hao, E-mail: sunhao_robert@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Hou, Xin-Yi, E-mail: hxy_pumc@126.com [Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing (China); Xue, Hua-Dan, E-mail: bjdanna95@hotmail.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Li, Xiao-Guang, E-mail: xglee88@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Jin, Zheng-Yu, E-mail: zhengyu_jin@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Qian, Jia-Ming, E-mail: qjiaming57@gmail.com [Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Yu, Jian-Chun, E-mail: yu-jch@163.com [Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Zhu, Hua-Dong, E-mail: huadongzhu@hotmail.com [Department of Emergency, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China)

    2015-05-15

    Highlights: • GIB is a common gastrointestinal emergency with a high mortality rate. • Detection and localization of GIB source are important for imaging modality. • DSDECTA using a dual-phase scan protocol is clinically feasible. • DSDECTA with VNE and iodine map images can diagnose the active GIB source accurately. • DSDECTA can reduce radiation dose compared with conventional CT examination in GIB. - Abstract: Objectives: To evaluate the clinical feasibility of dual-source dual-energy CT angiography (DSDECTA) with virtual non-enhanced images and iodine map for active gastrointestinal bleeding (GIB). Methods: From June 2010 to December 2012, 112 consecutive patients with clinical signs of active GIB underwent DSDECTA with true non-enhanced (TNE), arterial phase with single-source mode, and portal-venous phase with dual-energy mode (100 kVp/230 mAs and Sn 140 kVp/178 mAs). Virtual non-enhanced CT (VNE) image sets and iodine map were reformatted from ‘Liver VNC’ software. The mean CT number, noise, signal to noise ratio (SNR), image quality and radiation dose were compared between TNE and VNE image sets. Two radiologists, blinded to clinical data, interpreted images from DSDECTA with TNE (protocol 1), and DSDECTA with VNE and iodine map (protocol 2) respectively, with discordant interpretation resolved by consensus. The standards of reference included digital subtraction angiography, endoscopy, surgery, or final pathology reports. Receiver–operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) calculated for CT protocols 1 and 2, respectively. Results: There was no significant difference in mean CT numbers of all organs (including liver, pancreas, spleen, kidney, abdominal aorta, and psoas muscle) (P > 0.05). Lower noise and higher SNR were found on VNE images than TNE images (P < 0.05). Image quality of VNE was lower than that of TNE without significant difference (P > 0.05). The active GIB source was identified

  8. Dual-energy MDCT: Comparison of pulmonary artery enhancement on dedicated CT pulmonary angiography, routine and low contrast volume studies

    Energy Technology Data Exchange (ETDEWEB)

    Godoy, Myrna C.B., E-mail: migbarco@gmail.com [New York University Langone Medical Center, Department of Radiology, New York, NY (United States); University of Texas M.D. Anderson Cancer Center, Department of Diagnostic Radiology, Houston, TX (United States); Heller, Samantha L.; Naidich, David P.; Assadourian, Bernard [New York University Langone Medical Center, Department of Radiology, New York, NY (United States); Leidecker, Christianne [Siemens Medical Solutions, Malvern, PA (United States); Schmidt, Bernhard [Siemens Healthcare, Forchheim (Germany); Vlahos, Ioannis [New York University Langone Medical Center, Department of Radiology, New York, NY (United States); St. George' s Hospital NHS Trust, London (United Kingdom)

    2011-08-15

    Purpose: The aim of this study was (a) to compare arterial enhancement in simultaneously acquired high- and low-kilovoltage images; and (b) to determine whether low tube-voltage imaging would permit PE evaluation on routine chest CT studies or CTPA studies performed with a low volume of contrast media. Materials and methods: We compared 20 CTPA studies (CTPA group), 20 routine thoracic CT studies (RT group) and 10 CTPA studies performed with reduced volume of contrast media (RC group). HU values were measured in all groups at 80 kVp and 140 kVp images in multiple pulmonary arterial segments bilaterally. The diagnostic quality of the central and peripheral vascular enhancement and the image noise were evaluated at both energies using a five-point scale. Results: For all patients, the mean CT attenuation values were greater at 80 kVp than 140 kVp images (p < 0.001). At 80 kVp, CTPA group attenuation values were greater than RT group (p = 0.03) with a similar trend at 140 kVp (p = 0.08). At both 140 kVp and 80 kVp, CTPA group attenuation values were greater than RC group (p = 0.02 and p = 0.03, respectively). Qualitative analysis showed that at 140 kVp CTPA studies had better global image quality scores than RT (p = 0.003) and RC (p = 0.001) groups. However, at 80 kVp, there was no significant difference of global image quality between CTPA and the other groups (p = 0.4 and p = 0.5, respectively). Although measurable image noise was greater at 80 kVp than 140 kVp (p < 0.001), qualitative analysis revealed lower image noise at 80 kVp images. Conclusion: DECT at 80 kVp increases arterial enhancement in both CTPA and routine studies. For routine studies this results in central and peripheral enhancement quality equivalent to that of CTPA studies. Low tube-voltage imaging allows marked contrast volume reduction for CTPA. In selected cases, satisfactory lower radiation dose CT might be achievable using lower kVp imaging alone.

  9. Non-enhanced ECG-gated respiratory-triggered 3-D steady-state free-precession MR angiography with slab-selective inversion: initial experience in visualisation of renal arteries in free-breathing children without renal artery abnormality

    International Nuclear Information System (INIS)

    Klee, Dirk; Lanzman, Rotem Shlomo; Blondin, Dirk; Antoch, Gerald; Schaper, Joerg; Schmitt, Peter; Oh, Jun; Salgin, Burak; Mayatepek, Ertan

    2012-01-01

    ECG-gated non-enhanced balanced steady-state free precession (bSSFP) MR angiography requires neither breath-holding nor administration of contrast material. To investigate the image quality of free-breathing ECG-gated non-enhanced bSSFP MR angiography of renal arteries in children. Fourteen boys and seven girls (mean age, 9.7 years; range, 7 weeks-17 years) with no history of renovascular disease were included. MRI was performed at 1.5 T. Subjective image quality of axial and coronal maximum-intensity-projection reconstructions of four segments (I, aorta and renal artery ostium; II, main renal artery; III, segmental branches; IV, intrarenal vessels) was evaluated using a 4-point scale (4 = excellent, 3 = good, 2 = acceptable, 1 = non-diagnostic). Image quality was excellent for segments I (mean ± SD, 3.9 ± 0.3) and II (4.0 ± 0.1), good for segment III (3.4 ± 0.9) and acceptable for segment IV (2.3 ± 1.1). Mean image quality did not differ between sedated and non-sedated children. bSSFP MR angiography enables visualisation of renal arteries in children. (orig.)

  10. All-phase MR angiography using independent component analysis of dynamic contrast enhanced MRI time series. φ-MRA

    International Nuclear Information System (INIS)

    Suzuki, Kiyotaka; Matsuzawa, Hitoshi; Watanabe, Masaki; Nakada, Tsutomu; Nakayama, Naoki; Kwee, I.L.

    2003-01-01

    Dynamic contrast enhanced magnetic resonance imaging (dynamic MRI) represents a MRI version of non-diffusible tracer methods, the main clinical use of which is the physiological construction of what is conventionally referred to as perfusion images. The raw data utilized for constructing MRI perfusion images are time series of pixel signal alterations associated with the passage of a gadolinium containing contrast agent. Such time series are highly compatible with independent component analysis (ICA), a novel statistical signal processing technique capable of effectively separating a single mixture of multiple signals into their original independent source signals (blind separation). Accordingly, we applied ICA to dynamic MRI time series. The technique was found to be powerful, allowing for hitherto unobtainable assessment of regional cerebral hemodynamics in vivo. (author)

  11. Difference between Cr and Ni K-edge XANES spectra of rust layers formed on Fe-based binary alloys exposed to Cl-rich environment

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2005-01-01

    The rust layer formed on weathering steel possesses a strong protective ability against corrosives in an atmospheres. This ability is related to the structure of the rust layer. The difference in the protective ability of a rust layer. The difference in the protective ability of a rust layer in a Cl-rich environment between conventional weathering steel containing Cr and advanced weathering steel containing Ni is believed to be caused by the differences in local structural and chemical properties between alloying elements. Cr and Ni, in the rust layer. In order to examine the effect of these alloying elements on the structure of the rust layer formed on steel in a Cl-rich environment, we have performed Cr and Ni K-edge X-ray absorption near-edge structure (XANES) measurements for the rust layer of Fe-Cr and Fe-Ni binary alloys exposed to a Cl-rich atmosphere using synchrotron radiation. The results of the Cr K-edge XANES measurements for the rust layer of Fe-Cr binary alloys show that the atomic geometry around Cr depends on the concentration of Cr. Therefore, it is expected that the local structure around Cr in the rust layer is unstable. On the other hand, from the results of the Ni K-edge XANES measurements for the rust layer of Fe-Ni binary alloys. Ni is considered to be positioned at a specific site in the crystal structure of a constituent of the rust layer, such as akaganeite or magnetite. As a consequence, Ni negligibly interacts with Cl - ions in the rust layer. (author)

  12. Magnetic resonance angiography (MRA)

    International Nuclear Information System (INIS)

    Arlart, I.P.; Guhl, L.

    1992-01-01

    An account is given in this paper of the physical and technical principles underlying the 'time-of-flight' technique for imaging of vessels by magnetic resonance tomography. Major indications for the new procedure of magnetic resonance angiography at present are intracerebral and extracerebral vessels, with digital subtraction angiography quite often being required to cope with minor alterations (small aneurysms, small occlusions). Magnetic resonance angiography and digital subtraction angiography are compared to each other for advantages and disadvantages. Basically, replacement of radiological angiography by magnetic resonance angiography appears to be possible only within limits, since X-ray diagnostics primarily provides morphological information about vessels, whereas flow dynamics is visualized by the 'time-of-flight' technique. (orig.) [de

  13. Detailed imaging of the normal anatomy and pathologic conditions of the cavernous region at 3 Tesla using a contrast-enhanced MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Linn, Jennifer; Peters, Friederike; Lummel, Nina; Brueckmann, Hartmut; Yousry, Indra [University Hospital Munich, Department of Neuroradiology, Munich (Germany); Schankin, Christoph [University Hospital Munich, Department of Neurology, Munich (Germany); Rachinger, Walter [University Hospital Munich, Department of Neurosurgery, Munich (Germany)

    2011-12-15

    The purpose of this study was to evaluate the potential of a high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA) at 3 Tesla for the delineation of the cavernous sinus (CS) anatomy both under normal and under pathological conditions. Fifteen patients without pathologies in the CS and ten patients with pituitary adenomas were included. The CE-MRA was performed on a 3-Tesla scanner and analyzed collaboratively by two readers. The cranial nerves (CNs) within the CS, namely CNIII, CNIV, CNV1, CNV2, and CNVI, were identified in both patient groups. In the adenoma patients it was also assessed whether and to which extend the adenoma invaded the CS and the spatial relationship between tumor and CNs was determined. In the patients with normal CS anatomy, CNIII could be identified in 100%, CNIV in 86.7%, and CNV1, CNV2, as well as CNVI in 100% of analyzed sides. Pituitary adenomas invaded the CS unilaterally (right side) in four patients, and bilaterally in six patients. In patients with adenomas, the CN could be identified and differentiated from the tumor in the following percentages: CNIII in 100%, CNIV in 70%, both CNV1 and CNV2 in 90%, and CNVI in 100%. In all these cases, the tumor-nerve spatial relationship could be visualized. 3-Tesla CE-MRA allows detailed imaging of the complex anatomy of the CS and its structures. In adenoma patients, it clearly visualizes the spatial relationship between tumor and CNs, and thus might be helpful to optimize presurgical planning. (orig.)

  14. Evaluation of diabetic peripheral arterial disease in lower limb using 3.0 T contrast-enhanced MR angiography with simultaneous calf compression

    International Nuclear Information System (INIS)

    Li Jie; Zhao Jungong; Zhu Yueqi; Li Minghua; Wang Jue; Qiao Ruihua

    2011-01-01

    Objective: To determine the value of 3.0 T contrast-enhanced MR angiography (CE-MRA) with simultaneous calf compression in demonstrating and diagnosing diabetic peripheral vascular disease. Methods: Sixth-one patients with type 2 diabetes mellitus complicating vascular disease of lower limb were enrolled in this study. The patients included 37 males and 24 females with a mean age of (70±7.65) years. The mean duration of disease was (11.6±6.0) years. The patients were randomly divided into compression group (n=31) and conventional group (n=30). CE-MRA with a 3.0 T MR unit was performed in all patients. During CE-MRA, calf compression with a cuff was simultaneously applied to patients of compression group. DSA, which was regarded as gold standard, was conducted within one week after the procedure. The quality of MRA images was separately evaluated by two radiologists, the results were compared between two groups. Results: Taking DSA findings as reference, the image quality of calf and foot in compression group was much better than that in conventional group (P 50% arterial stenosis or occlusion of leg the image in compression group was also better than that in conventional group (P<0.05). CE-MRA with simultaneous calf compression could significantly eliminate the overlapping venous shadow (P<0.05). Conclusion: The 3.0 T CE-MRA with simultaneous calf compression is a simple and practical technique, it can markedly improve the image quality as well as the diagnostic accuracy of peripheral vascular disease of lower limb in diabetic patients. (authors)

  15. Portosystemic collateral circulation in the falciform ligament: evaluation with three dimensional dynamic contrast enhanced MR angiography in patients with portal hypertension

    International Nuclear Information System (INIS)

    Wu Zhuo; Liang Biling; Li Yong; Zhong Jinglian; Ye Ruixin; Zhang Rong

    2009-01-01

    Objective: The purpose of our study was to investigate three dimensional dynamic contrast enhanced MR angiography(3D DCE MRA) in the detection of portosystemic collateral circulation in the falciform ligament in patients with portal hypertension. Methods: From April 2003 to July 2008, 53 portal hypertension patients with varices in the falciform ligament were evaluated with 3D DCE MRA. Two radiologists independently assessed the number, diameter, location and drainages of the portosystemic collateral circulation in the falciform ligament according to the information on the 3D DCE MRA. Results: The veins in the falciform ligament were classified into the superior and inferior groups, and both groups arise from the left trunk of the portal vein. In our study, the number of varices detected on 3D DCE MRA images varied from 1 to 3, and the diameters of these vessels varied from 0.4 to 2.6 cm. The inferior group consisted of paraumbilical/umbilical veins (47 cases), which flowed toward umbilicus and then drained upwards (n=16) including deep superior epigastric veins (n=7), superficial superior epigastric veins (n=9), downwards (n=40) including deep inferior epigastric veins (n=7), superficial inferior epigastric veins (n=33), or upwards and downwards at the same time (n=9). The superior group of vessels in the falciform ligament were directly anastomosed with the internal thoracic vessels (n=6). Conclusion: In patients with portal hypertension, 3D DCE MRA can optimally demonstrate the portosystemic collateral circulation in the falciform ligament, which includes the superior and inferior drainage groups. (authors)

  16. Improved vessel morphology measurements in contrast-enhanced multi-detector computed tomography coronary angiography with non-linear post-processing

    International Nuclear Information System (INIS)

    Ferencik, Maros; Lisauskas, Jennifer B.; Cury, Ricardo C.; Hoffmann, Udo; Abbara, Suhny; Achenbach, Stephan; Karl, W. Clem; Brady, Thomas J.; Chan, Raymond C.

    2006-01-01

    Multi-detector computed tomography (MDCT) permits detection of coronary plaque. However, noise and blurring impair accuracy and precision of plaque measurements. The aim of the study was to evaluate MDCT post-processing based on non-linear image deblurring and edge-preserving noise suppression for measurements of plaque size. Contrast-enhanced MDCT coronary angiography was performed in four subjects (mean age 55 ± 5 years, mean heart rate 54 ± 5 bpm) using a 16-slice scanner (Siemens Sensation 16, collimation 16 x 0.75 mm, gantry rotation 420 ms, tube voltage 120 kV, tube current 550 mAs, 80 mL of contrast). Intravascular ultrasound (IVUS; 40 MHz probe) was performed in one vessel in each patient and served as a reference standard. MDCT vessel cross-sectional images (1 mm thickness) were created perpendicular to centerline and aligned with corresponding IVUS images. MDCT images were processed using a deblurring and edge-preserving noise suppression algorithm. Then, three independent blinded observers segmented lumen and outer vessel boundaries in each modality to obtain vessel cross-sectional area and wall area in the unprocessed MDCT cross-sections, post-processed MDCT cross-sections and corresponding IVUS. The wall area measurement difference for unprocessed and post-processed MDCT images relative to IVUS was 0.4 ± 3.8 mm 2 and -0.2 ± 2.2 mm 2 (p 2 , respectively. In conclusion, MDCT permitted accurate in vivo measurement of wall area and vessel cross-sectional area as compared to IVUS. Post-processing to reduce blurring and noise reduced variability of wall area measurements and reduced measurement bias for both wall area and vessel cross-sectional area

  17. Time-Resolved Three-Dimensional Contrast-Enhanced Magnetic Resonance Angiography in Patients with Chronic Expanding and Stable Aortic Dissections

    Directory of Open Access Journals (Sweden)

    Michael Trojan

    2017-01-01

    Full Text Available Objective. To prospectively evaluate our hypothesis that three-dimensional time-resolved contrast-enhanced magnetic resonance angiography (TR-MRA is able to detect hemodynamic alterations in patients with chronic expanding aortic dissection compared to stable aortic dissections. Materials and Methods. 20 patients with chronic or residual aortic dissection in the descending aorta and patent false lumen underwent TR-MRA of the aorta at 1.5 T and repeated follow-up imaging (mean follow-up 5.4 years. 7 patients showed chronic aortic expansion and 13 patients had stable aortic diameters. Regions of interest were placed in the nondissected ascending aorta and the false lumen of the descending aorta at the level of the diaphragm (FL-diaphragm level resulting in respective time-intensity curves. Results. For the FL-diaphragm level, time-to-peak intensity and full width at half maximum were significantly shorter in the expansion group compared to the stable group (p=0.027 and p=0.003, and upward and downward slopes of time-intensity curves were significantly steeper (p=0.015 and p=0.005. The delay of peak intensity in the FL-diaphragm level compared to the nondissected ascending aorta was significantly shorter in the expansion group compared to the stable group (p=0.01. Conclusions. 3D TR-MRA detects significant alterations of hemodynamics within the patent false lumen of chronic expanding aortic dissections compared to stable aortic dissections.

  18. Assessment of brain maturation in the preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN)

    International Nuclear Information System (INIS)

    Ling, Xueying; Tang, Wen; Liu, Guosheng; Huang, Li; Li, Bingxiao; Li, Xiaofei; Liu, Sirun; Xu, Jing

    2013-01-01

    Purpose: To assess the brain maturation of preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN). Materials and methods: Conventional magnetic resonance imaging (MRI), DTI and ESWAN were performed in 60 preterm infants and 21 term controls. 60 preterm infants were subgrouped to two groups according to the age at imaging: before and at term-equivalent age (TEA). Fractional anisotropy (FA), apparent diffusion coefficient (ADC) map from DTI, T 2 * and R 2 * maps from ESWAN were post-processed at an off-line workstation. The values of FA, ADC, T 2 * and R 2 * from the posterior limb of internal capsule (PLIC), frontal white matter (FWM), occipital white matter (OWM) and lentiform nuclei (LN) were determined. These parameters were compared between preterm and term infants. Correlations of DTI and ESWAN parameters with the gestational age, postmenstrual age and postnatal age were analyzed. Results: ADCs of FWM, OWM and LN, and T 2 * values of the PLIC and LN were higher in the preterm infants at TEA compared with the term controls. The correlations were existed between the postmenstrual age and the values of FA, ADC, T 2 *, R 2 * from the PLIC, values of ADC, T 2 *, R 2 * from the LN, T 2 * value from the OWM. The correlations were also found between the postnatal age and the values of FA, ADC, T 2 * from the PLIC, and T 2 * value from the LN. Conclusion: The maturity of preterm brain around TEA was different from that of term controls and appeared to be independent of the prematurity at birth. T 2 * was one of valuable indices to evaluate brain maturation in preterm infants

  19. Assessment of brain maturation in the preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN)

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Xueying, E-mail: lingxuey@163.com [Department of Medical Imaging Center, the First Affiliated Hospital, Jinan University, Guangzhou (China); Tang, Wen [Department of Medical Imaging Center, the First Affiliated Hospital, Jinan University, Guangzhou (China); Liu, Guosheng [Neonatal Intensive Care Unit, the First Affiliated Hospital, Jinan University, Guangzhou (China); Huang, Li [Department of Medical Imaging Center, the First Affiliated Hospital, Jinan University, Guangzhou (China); Li, Bingxiao [Neonatal Intensive Care Unit, the First Affiliated Hospital, Jinan University, Guangzhou (China); Li, Xiaofei; Liu, Sirun [Department of Medical Imaging Center, the First Affiliated Hospital, Jinan University, Guangzhou (China); Xu, Jing [Neonatal Intensive Care Unit, the First Affiliated Hospital, Jinan University, Guangzhou (China)

    2013-09-15

    Purpose: To assess the brain maturation of preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN). Materials and methods: Conventional magnetic resonance imaging (MRI), DTI and ESWAN were performed in 60 preterm infants and 21 term controls. 60 preterm infants were subgrouped to two groups according to the age at imaging: before and at term-equivalent age (TEA). Fractional anisotropy (FA), apparent diffusion coefficient (ADC) map from DTI, T{sub 2}* and R{sub 2}* maps from ESWAN were post-processed at an off-line workstation. The values of FA, ADC, T{sub 2}* and R{sub 2}* from the posterior limb of internal capsule (PLIC), frontal white matter (FWM), occipital white matter (OWM) and lentiform nuclei (LN) were determined. These parameters were compared between preterm and term infants. Correlations of DTI and ESWAN parameters with the gestational age, postmenstrual age and postnatal age were analyzed. Results: ADCs of FWM, OWM and LN, and T{sub 2}* values of the PLIC and LN were higher in the preterm infants at TEA compared with the term controls. The correlations were existed between the postmenstrual age and the values of FA, ADC, T{sub 2}*, R{sub 2}* from the PLIC, values of ADC, T{sub 2}*, R{sub 2}* from the LN, T{sub 2}* value from the OWM. The correlations were also found between the postnatal age and the values of FA, ADC, T{sub 2}* from the PLIC, and T{sub 2}* value from the LN. Conclusion: The maturity of preterm brain around TEA was different from that of term controls and appeared to be independent of the prematurity at birth. T{sub 2}* was one of valuable indices to evaluate brain maturation in preterm infants.

  20. Detailed imaging of the normal anatomy and pathologic conditions of the cavernous region at 3 Tesla using a contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Linn, Jennifer; Peters, Friederike; Lummel, Nina; Brueckmann, Hartmut; Yousry, Indra; Schankin, Christoph; Rachinger, Walter

    2011-01-01

    The purpose of this study was to evaluate the potential of a high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA) at 3 Tesla for the delineation of the cavernous sinus (CS) anatomy both under normal and under pathological conditions. Fifteen patients without pathologies in the CS and ten patients with pituitary adenomas were included. The CE-MRA was performed on a 3-Tesla scanner and analyzed collaboratively by two readers. The cranial nerves (CNs) within the CS, namely CNIII, CNIV, CNV1, CNV2, and CNVI, were identified in both patient groups. In the adenoma patients it was also assessed whether and to which extend the adenoma invaded the CS and the spatial relationship between tumor and CNs was determined. In the patients with normal CS anatomy, CNIII could be identified in 100%, CNIV in 86.7%, and CNV1, CNV2, as well as CNVI in 100% of analyzed sides. Pituitary adenomas invaded the CS unilaterally (right side) in four patients, and bilaterally in six patients. In patients with adenomas, the CN could be identified and differentiated from the tumor in the following percentages: CNIII in 100%, CNIV in 70%, both CNV1 and CNV2 in 90%, and CNVI in 100%. In all these cases, the tumor-nerve spatial relationship could be visualized. 3-Tesla CE-MRA allows detailed imaging of the complex anatomy of the CS and its structures. In adenoma patients, it clearly visualizes the spatial relationship between tumor and CNs, and thus might be helpful to optimize presurgical planning. (orig.)

  1. Feasibility of MR-guided angioplasty of femoral artery stenoses using real-time imaging and intraarterial contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Paetzel, C.; Zorger, N.; Bachthaler, M.; Voelk, M.; Seitz, J.; Herold, T.; Feuerbach, S.; Lenhart, M.; Nitz, W.R.

    2004-01-01

    Purpose: To show the feasibility of magnetic resonance (MR) for guided interventional therapy of femoral and popliteal artery stenoses with commercially available materials supported by MR real-time imaging and intraarterial MR angiography. Materials and Methods: Three patients (1 female, 2 male), suffering from symptomatic arterial occlusive disease with stenoses of the femoral (n=2) or popliteal (n=1) arteries were included. Intraarterial digital subtraction angiography was performed in each patient pre- and post-interventionally as standard of reference to quantify stenoses. The degree of the stenoses reached from 71-88%. The MR images were acquired on a 1.5 T MR scanner (Magnetom Sonata; Siemens, Erlangen, Germany). For MR-angiography, a Flash 3D sequence was utilized following injection of 5 mL diluted gadodiamide (Omniscan; Amersham Buchler, Braunschweig, Germany) via the arterial access. Two maximum intensity projections (MIP) were used as road maps and localizer for the interactive positioning of a continuously running 2D-FLASH sequence with a temporal solution of 2 images per second. During the intervention, an MR compatible monitor provided the image display inside the scanner room. Safety guidelines were followed during imaging in the presence of a conductive guidewire. The lesion was crossed by a commercially available balloon catheter (Wanda, Boston Scientific; Ratingen, Germany), which was mounted on a 0.035'' guidewire (Terumo; Leuven, Belgium). The visibility was provided by radiopaque markers embedded in the balloon and was improved by injection of 1 mL gadodiamide into the balloon. After dilation, the result was checked by intraarterial MR angiography and catheter angiography. Results: The stenoses could be correctly localized by intraarterial MR angiography. There was complete correlation between intraarterial MR angiography and digital subtraction angiography. The combination of guidewire and balloon was visible and the balloon was placed

  2. K-edge x-ray dichroism investigation of Fe1−xCoxSi: Experimental evidence for spin polarization crossover

    International Nuclear Information System (INIS)

    Hearne, G.R.; Diguet, G.; Baudelet, F.; Itié, J.-P.; Manyala, N.

    2015-01-01

    Both Fe and Co K-edge x-ray magnetic circular dichroism (XMCD) have been employed as element-specific probes of the magnetic moments in the composition series of the disordered ferromagnet Fe 1−x Co x Si (for x=0.2, 0.3, 0.4, 0.5). A definitive single peaked XMCD profile occurs for all compositions at both Fe and Co K-edges. The Fe 4p orbital moment, deduced from the integral of the XMCD signal, has a steep dependence on x at low doping levels and evolves to a different (weaker) dependence at x≥0.3, similar to the behavior of the magnetization in the Co composition range studied here. It is systematically higher, by at least a factor of two, than the corresponding Co orbital moment for most of the composition series. Fine structure beyond the K-edge absorption (limited range EXAFS) suggests that the local order (atomic environment) is very similar across the series, from the perspective of both the Fe and Co absorbing atom. The variation in the XMCD integral across the Co composition range has two regimes, that which occurs below x=0.3 and then evolves to different behavior at higher doping levels. This is more conspicuously present in the Fe contribution. This is rationalized as the evolution from a half-metallic ferromagnet at low Co doping to that of a strong ferromagnet at x>0.3 and as such, spin polarization crossover occurs. The Fermi level is tuned from the majority spin band for x<0.3 where a strongly polarized majority spin electron gas prevails, to a regime where minority spin carriers dominate at higher doping. The evolution of the Fe-derived spin polarized (3d) bands, indirectly probed here via the 4p states, is the primary determinant of the doping dependence of the magnetism in this alloy series. - Highlights: • Element-specific probing of the electronic structure of the Fe 1−x Co x Si series. • XMCD at the level of 10 −4 at the K-edge in such low-moment systems. • Element-specific probing of magnetic contributions from both Fe and Co

  3. Electron-beam induced amorphization of stishovite: Silicon-coordination change observed using Si K-edge extended electron energy-loss fine structure

    International Nuclear Information System (INIS)

    Aken, P.A. van; Sharp, T.G.; Seifert, F.

    1998-01-01

    The analysis of the extended energy-loss fine structure (EXELFS) of the Si K-edge for sixfold-coordinated Si in synthetic stishovite and fourfold-coordinated Si in natural α-quartz is reported by using electron energy-loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM). The stishovite Si K-edge EXELFS spectra were measured as a time-dependent series to document irradiation-induced amorphization. The amorphization was also investigated through the change in Si K- and O K-edge energy-loss near edge structure (ELNES). For α-quartz, in contrast to stishovite, electron irradiation-induced vitrification, produced no detectable changes of the EXELFS. The Si K-edge EXELFS were analysed with the classical extended X-ray absorption fine structure (EXAFS) treatment and compared to ab initio curve-waved multiple-scattering (MS) calculations of EXAFS spectra for stishovite and α-quartz. Highly accurate information on the local atomic environment of the silicon atoms during the irradiation-induced amorphization of stishovite is obtained from the EXELFS structure parameters The mean Si-O bond distance R and mean Si coordination number N changes from R=0.1775 nm and N=6 for stishovite through a disordered intermediate state (R∼0.172 nm and N∼5) to R∼0.167 nm and N∼4.5 for a nearly amorphous state similar to α-quartz (R=0.1609 nm and N=4). During the amorphization process, the Debye-Waller factor (DWF) passes through a maximum value of σ N 2 ∼83.8pm 2 as it changes from σ st 2 =51.8pm 2 for sixfold to σ qu 2 =18.4pm 2 for fourfold coordination of Si. This increase in Debye-Waller factor indicates an increase in mean-square relative displacement (MSRD) between the central silicon atom and its oxygen neighbours. Using the EXELFS data for amorphization, a new method is developed to derive the relative amounts of Si coordinations in high-pressure minerals with mixed coordination. For the radiation-induced amorphization process of

  4. Electron-beam induced amorphization of stishovite: Silicon-coordination change observed using Si K-edge extended electron energy-loss fine structure

    Science.gov (United States)

    van Aken, P. A.; Sharp, T. G.; Seifert, F.

    The analysis of the extended energy-loss fine structure (EXELFS) of the Si K-edge for sixfold-coordinated Si in synthetic stishovite and fourfold-coordinated Si in natural α-quartz is reported by using electron energy-loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM). The stishovite Si K-edge EXELFS spectra were measured as a time-dependent series to document irradiation-induced amorphization. The amorphization was also investigated through the change in Si K- and O K-edge energy-loss near edge structure (ELNES). For α-quartz, in contrast to stishovite, electron irradiation-induced vitrification, verified by selected area electron diffraction (SAED), produced no detectable changes of the EXELFS. The Si K-edge EXELFS were analysed with the classical extended X-ray absorption fine structure (EXAFS) treatment and compared to ab initio curve-waved multiple-scattering (MS) calculations of EXAFS spectra for stishovite and α-quartz. Highly accurate information on the local atomic environment of the silicon atoms during the irradiation-induced amorphization of stishovite is obtained from the EXELFS structure parameters (Si-O bond distances, coordination numbers and Debye-Waller factors). The mean Si-O bond distance R and mean Si coordination number N changes from R=0.1775 nm and N=6 for stishovite through a disordered intermediate state (R 0.172 nm and N 5) to R 0.167 nm and N 4.5 for a nearly amorphous state similar to α-quartz (R=0.1609 nm and N=4). During the amorphization process, the Debye-Waller factor (DWF) passes through a maximum value of as it changes from for sixfold to for fourfold coordination of Si. This increase in Debye-Waller factor indicates an increase in mean-square relative displacement (MSRD) between the central silicon atom and its oxygen neighbours that is consistent with the presence of an intermediate structural state with fivefold coordination of Si. The distribution of coordination states can be estimated by

  5. Cl K-edge XANES spectra of atmospheric rust on Fe, Fe-Cr and Fe-Ni alloys exposed to saline environment

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2004-01-01

    Cl K-edge XANES measurements of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys in chloride pollution have been performed using synchrotron radiation in order to clarify roles of anticorrosive alloying elements and of Cl in the corrosion resistance of weathering steel. The spectra of binary alloys show a shoulder structure near the absorption edge. The intensity of the shoulder peak depends on the kind and amount of the alloying element, whereas the energy position is invariant. This indicates that Cl is not combined directly with alloying elements in the rust. (author)

  6. Resonant inelastic x-ray scattering on iso-C2H2Cl2 around the chlorine K-edge: Structural and dynamical aspects

    International Nuclear Information System (INIS)

    Kawerk, Elie; Carniato, Stéphane; Journel, Loïc; Marchenko, Tatiana; Simon, Marc; Piancastelli, Maria Novella; Žitnik, Matjaž; Bučar, Klemen; Bohnic, Rok

    2014-01-01

    We report a theoretical and experimental study of the high resolution resonant K α X-ray emission lines around the chlorine K-edge in gas phase 1,1-dichloroethylene. With the help of ab initio electronic structure calculations and cross section evaluation, we interpret the lowest lying peak in the X-ray absorption and emission spectra. The behavior of the K α emission lines with respect to frequency detuning highlights the existence of femtosecond nuclear dynamics on the dissociative Potential Energy Surface of the first K-shell core-excited state

  7. Resonant inelastic x-ray scattering on iso-C2H2Cl2 around the chlorine K-edge: Structural and dynamical aspects

    Science.gov (United States)

    Kawerk, Elie; Carniato, Stéphane; Journel, Loïc; Marchenko, Tatiana; Piancastelli, Maria Novella; Žitnik, Matjaž; Bučar, Klemen; Bohnic, Rok; Kavčič, Matjaž; Céolin, Denis; Khoury, Antonio; Simon, Marc

    2014-10-01

    We report a theoretical and experimental study of the high resolution resonant Kα X-ray emission lines around the chlorine K-edge in gas phase 1,1-dichloroethylene. With the help of ab initio electronic structure calculations and cross section evaluation, we interpret the lowest lying peak in the X-ray absorption and emission spectra. The behavior of the Kα emission lines with respect to frequency detuning highlights the existence of femtosecond nuclear dynamics on the dissociative Potential Energy Surface of the first K-shell core-excited state.

  8. Resonant inelastic x-ray scattering on iso-C₂H₂Cl₂ around the chlorine K-edge: structural and dynamical aspects.

    Science.gov (United States)

    Kawerk, Elie; Carniato, Stéphane; Journel, Loïc; Marchenko, Tatiana; Piancastelli, Maria Novella; Žitnik, Matjaž; Bučar, Klemen; Bohnic, Rok; Kavčič, Matjaž; Céolin, Denis; Khoury, Antonio; Simon, Marc

    2014-10-14

    We report a theoretical and experimental study of the high resolution resonant K(α) X-ray emission lines around the chlorine K-edge in gas phase 1,1-dichloroethylene. With the help of ab initio electronic structure calculations and cross section evaluation, we interpret the lowest lying peak in the X-ray absorption and emission spectra. The behavior of the K(α) emission lines with respect to frequency detuning highlights the existence of femtosecond nuclear dynamics on the dissociative Potential Energy Surface of the first K-shell core-excited state.

  9. MR-angiography

    International Nuclear Information System (INIS)

    Seiderer, M.

    1989-01-01

    Three categories of MRI techniques for vascular imaging are discussed: 2d-angiography using rephasing and dephasing pulse sequences and slice selective imaging; 3d-angiography using rehpasing and dephasing pulse sequences and fas 3d-imaging techniques; 3d-angiography using signal intensity modulation caused by pre- and post-contrast data acquisition (e.g. Gadolinium-DTPA) in combination with fast 3d-imaging (only one type of pulse sequence). (H.W.). 6 figs

  10. Abdominal MR angiography

    International Nuclear Information System (INIS)

    Wegmueller, H.; Vock, P.

    1993-01-01

    The two techniques currently most often used for MR angiography, those based on time-of-flight effects and on phase-contrast, are introduced, and our results with three-dimensional phase contrast angiography of the abdomen are presented. Several basic differences from other imaging procedures render MR angiography clinically useful for screening for renal artery stenosis in critical situations, such as renal failure or intolerance to contrast agents. In the future, the spectrum of applications of MR angiography will broaden and include other indications, such as portal venous hypertension and follow-up studies after surgical portal systemic shunting. (orig.) [de

  11. Advantages of T2 reversed fast spin-echo image and enhanced three-dimensional surface MR angiography for the diagnosis of cerebral arteriovenous malformations

    International Nuclear Information System (INIS)

    Tanabe, Sumiyoshi; Honmou, Osamu; Minamida, Yoshihiro; Hashi, Kazuo

    2001-01-01

    Although the anatomical investigation of cerebral arteriovenous malformation (AVM) with conventional neuro-imagings considerably supports the preoperative evaluation, it is still hard to dissect the detailed anatomical conformations of AVMs such as location of nidus, identification of feeding arteries or draining veins, and the three-dimensional configuration of nidus in sulci or gyri. In this study, we investigated the efficacy of enhanced three-dimensional surface MR angiography (surface MRA) and T2 reversed image (T2R image) in the diagnosis and surgical planning for cerebral AVMs. The diagnostic accuracy was studied in twelve AVMs: four AVMs closed to motor area, one to Broca area, one to Wernicke area, four in temporal lobe, and two in occipital lobe. Images were obtained with a SIGNA HORIZON LX 1.5T VER 8.2. To construct T2R, the brain is scanned by fast SE method with long TR and was displayed with the reversed gray scale, which seemed similar to T1WI. Surface MRA is a fusion image of MRA and surface image in the workstation. The original data was obtained by enhanced 3D-SPGR method. MRA image was reconstructed with MIP method, and surface image was manipulated with a volume rendering method. T2R images demonstrated seven sulcal AVMs, three gyral AVMs, and two sulco-gyral AVMs; five AVMs located on cortex, four extended to subcortex, and three to paraventricular brain. The images clearly showed six AVMs had hypervascular network such as modja-modja vascular formation. Surface MRA represented nidus adjacent to eloquent area. They were present in central sulcus, precentral sulcus, intraparietal sulcus, inferior frontal sulcus, sylvian fissure, superior temporal sulcus, inferior temporal sulcus, superior temporal gyrus, inferior temporal gyrus, medial temporal gyrus, premotor area and superior frontal sulcus, precuneus and parieto-occipital sulcus. It was easy to identify the point of feeding arteries going down into the sulcus and the junction-point of nidus

  12. Advantages of T2 reversed fast spin-echo image and enhanced three-dimensional surface MR angiography for the diagnosis of cerebral arteriovenous malformations

    Energy Technology Data Exchange (ETDEWEB)

    Tanabe, Sumiyoshi; Honmou, Osamu; Minamida, Yoshihiro; Hashi, Kazuo [Sapporo Medical Univ. (Japan). School of Medicine

    2001-09-01

    Although the anatomical investigation of cerebral arteriovenous malformation (AVM) with conventional neuro-imagings considerably supports the preoperative evaluation, it is still hard to dissect the detailed anatomical conformations of AVMs such as location of nidus, identification of feeding arteries or draining veins, and the three-dimensional configuration of nidus in sulci or gyri. In this study, we investigated the efficacy of enhanced three-dimensional surface MR angiography (surface MRA) and T2 reversed image (T2R image) in the diagnosis and surgical planning for cerebral AVMs. The diagnostic accuracy was studied in twelve AVMs: four AVMs closed to motor area, one to Broca area, one to Wernicke area, four in temporal lobe, and two in occipital lobe. Images were obtained with a SIGNA HORIZON LX 1.5T VER 8.2. To construct T2R, the brain is scanned by fast SE method with long TR and was displayed with the reversed gray scale, which seemed similar to T1WI. Surface MRA is a fusion image of MRA and surface image in the workstation. The original data was obtained by enhanced 3D-SPGR method. MRA image was reconstructed with MIP method, and surface image was manipulated with a volume rendering method. T2R images demonstrated seven sulcal AVMs, three gyral AVMs, and two sulco-gyral AVMs; five AVMs located on cortex, four extended to subcortex, and three to paraventricular brain. The images clearly showed six AVMs had hypervascular network such as modja-modja vascular formation. Surface MRA represented nidus adjacent to eloquent area. They were present in central sulcus, precentral sulcus, intraparietal sulcus, inferior frontal sulcus, sylvian fissure, superior temporal sulcus, inferior temporal sulcus, superior temporal gyrus, inferior temporal gyrus, medial temporal gyrus, premotor area and superior frontal sulcus, precuneus and parieto-occipital sulcus. It was easy to identify the point of feeding arteries going down into the sulcus and the junction-point of nidus

  13. Utilizing generalized autocalibrating partial parallel acquisition (GRAPPA) to achieve high-resolution contrast-enhanced MR angiography of hepatic artery: Initial experience in orthotopic liver transplantation candidates

    International Nuclear Information System (INIS)

    Xu Pengju; Yan Fuhua; Wang Jianhua; Lin Jiang; Fan Jia

    2007-01-01

    Objective: To evaluate feasibility of using GRAPPA to acquire high-resolution 3D contrast-enhanced MR angiography (CE-MRA) of hepatic artery and value of GRAPPA for displaying vessels anatomy. Materials and methods: High-resolution CE-MRA using GRAPPA was performed in 67 orthotopic liver transplantation recipient candidates. Signal intensity (SI) and relative SI, i.e., Cv-ro (vessel-to-liver contrast) of the aorta and the hepatic common artery (HCA), were measured. The SI and the relative SI were compared and analyzed using T-test. For purpose of qualitative evaluation, the vessel visualization quality and the order of depicted hepatic artery branches were evaluated by two radiologists independently and assessed by weighted kappa analysis. The depiction of hepatic arterial anatomy and variations was evaluated, and results were correlated with the findings in surgery. Results: The mean SI values were 283.29 ± 65.07 (mean ± S.D.) for aorta and 283.16 ± 64.07 for HCA, respectively. The mean relative SI values were 0.698 ± 0.09 for aorta and 0.696 ± 0.09 for HCA, respectively. Homogeneous enhancement between aorta and HCA was confirmed by statistically insignificant differences (p-values were 0.89 for mean SI values and 0.12 for mean relative SI values, respectively). The average score for vessel visualization ranged from good to excellent for different artery segments. Overall interobserver agreement in the visualization of different artery segments was excellent (kappa value > 0.80). The distal intrahepatic segmental arteries were well delineated for majority of patients with excellent interobserver agreement. Normal hepatic arterial anatomy was correctly demonstrated in 53 patients, and arterial anomalies were accurately detected on high-resolution MRA image of all 14 patients. Conclusion: High-resolution hepatic artery MRA acquired using GRAPPA in a reproducible manner excellently depicts and delineates small vessels and can be routinely used for evaluating

  14. Rapid line scan MR angiography

    International Nuclear Information System (INIS)

    Frahm, J.; Merboldt, K.D.; Hanicke, W.; Bruhn, H.

    1987-01-01

    Direct MR angiography may be performed using line scan imaging techniques combined with presaturation of stationary spins. Thus, a single line scan echo yields a projection of vessels due to the signal from reflowing unsaturated spins. Reconstruction of an angiographic image is performed line by line at slightly incremented positions. In particular, line scan angiography is direct and fast without a sensitivity to artifacts even for high flow rates. Image resolution and field of view may be chosen without restrictions, and zoom images using enhanced gradients may be recorded without aliasing artifacts. The method is robust with respect to eddy currents and pulsatile flow. Line scan MR angiograms of phantoms, animals, and human volunteers have been recorded using 90 0 radio frequency pulses and gradient-recalled echoes

  15. Charge-transfer and Mott-Hubbard Excitations in FeBo3: Fe K-edge resonant Inelastic x-ray scattering study

    International Nuclear Information System (INIS)

    Kim, J.; Shvydko, Y.

    2011-01-01

    Momentum-resolved resonant inelastic x-ray scattering (RIXS) spectroscopy has been carried out successfully at the Fe K-edge for the first time. The RIXS spectra of a FeBO 3 single crystal reveal a wealth of information on ∼ 1-10 eV electronic excitations. The IXS signal resonates when the incident photon energy approaches the pre-edge (1s - -3d) and the main-edge (1s - -4p) of the Fe K-edge absorption spectrum. The RIXS spectra measured at the pre-edge and the main-edge show quantitatively different dependences on the incident photon energy, momentum transfer, photon polarization, and temperature. We present a multielectron analysis of the Mott-Hubbard (MH) and charge transfer (CT) excitations, and calculate their energies. Electronic excitations observed in the pre-edge and main-edge RIXS spectra are interpreted as MH and CT excitations, respectively. We propose the electronic structure around the chemical potential in FeBO 3 based on the experimental data.

  16. Arsenic K-edge X-ray absorption near-edge spectroscopy to determine oxidation states of arsenic of a coastal aquifer–aquitard system

    International Nuclear Information System (INIS)

    Wang, Ya; Jiao, Jiu Jimmy; Zhu, Sanyuan; Li, Yiliang

    2013-01-01

    Determination of oxidation states of solid-phase arsenic in bulk sediments is a valuable step in the evaluation of its bioavailability and environmental fate in deposits, but is difficult when the sediments have low arsenic contents and heterogeneous distribution of arsenic species. As K-edge X-ray absorption near-edge spectroscopy (XANES) was used to determine quantitatively the oxidation states of arsenic in sediments collected from different depths of boreholes in the Pearl River Delta, China, where the highest aquatic arsenic concentration is 161.4 μg/L, but the highest solid arsenic content only 39.6 mg/kg. The results demonstrated that XANES is efficient in determining arsenic oxidation states of the sediments with low arsenic contents and multiple arsenic species. The study on the high-resolution vertical variations of arsenic oxidation states also indicated that these states are influenced strongly by groundwater activities. With the help of geochemical data, solid arsenic speciation, toxicity and availability were further discussed. -- Highlights: •XANES is efficient in determining arsenic oxidation states of the bulk sediments. •Distribution of arsenic oxidation states is consistent with geochemical conditions. •Arsenic oxidation states are influenced strongly by groundwater activities. -- As K-edge X-ray absorption near-edge spectroscopy is efficient in determining arsenic oxidation states of the bulk sediments with low arsenic contents and heterogeneous distribution of arsenic species

  17. Nitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hiroyuki; Fukao, Taishi; Minami, Hirotake; Ukai, Masatoshi [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588 (Japan); Fujii, Kentaro; Yokoya, Akinari [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Fukuda, Yoshihiro; Saitoh, Yuji [Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Sayo-gun, Hyougo 679-5148 (Japan)

    2014-08-07

    The N K-edge X-ray absorption near edge structure (XANES) spectra of the purine-containing nucleotide, guanosine 5{sup ′}-monophosphate (GMP), in aqueous solution are measured under various pH conditions. The spectra show characteristic peaks, which originate from resonant excitations of N 1s electrons to π* orbitals inside the guanine moiety of GMP. The relative intensities of these peaks depend on the pH values of the solution. The pH dependence is explained by the core-level shift of N atoms at specific sites caused by protonation and deprotonation. The experimental spectra are compared with theoretical spectra calculated by using density functional theory for GMP and the other purine-containing nucleotides, adenosine 5{sup ′}-monophosphate, and adenosine 5{sup ′}-triphosphate. The N K-edge XANES spectra for all of these nucleotides are classified by the numbers of N atoms with particular chemical bonding characteristics in the purine moiety.

  18. Non-destructive assay system for uranium and plutonium in reprocessing input solutions. Hybrid K-edge/XRF Densitometer. JASPAS JC-11 final report

    International Nuclear Information System (INIS)

    Surugaya, N.; Abe, K.; Kurosawa, A.; Ikeda, H.; Kuno, Y.

    1997-05-01

    As a part of JASPAS programme, a non-radioactive assay system for the accountability of uranium and plutonium in input dissolver solutions of a spent fuel reprocessing plant, called Hybrid K-edge/XRF Densitometer, has been developed at the Tokai Reprocessing plant (TRP) since 1991. The instrument is the one of the hybrid type combined K-edge densitometry (KED) and X-ray fluorescence (XRF) analysis. The KED is used to determine the uranium concentration and the XRF is used to determine the U/Pu ratio. These results give the plutonium concentration in consequence. It is considered that the instrument has the capability of timely on-site verification for input accountancy. The instrument had been installed in the analytical hot cell at the TRP and the experiments comparing with Isotope Dilution Mass Spectrometry (IDMS) method have been carried out. As the results of measurements for the actual input solutions in the acceptance and performance tests, it was typically confirmed that the precision for determining uranium concentration by the KED was within 0.2%, whereas the XRF for plutonium performed within 0.7%. This final report summarizes the design information and performance data so as to end the JASPAS programme. (author)

  19. Fat-Suppressed Gadolinium-Enhanced Three-Dimensional Magnetic Resonance Angiography Adequately Depicts the Status of Iliac Arteries Following Atherectomy and Stent Placement

    International Nuclear Information System (INIS)

    Amano, Yasuo; Gemma, Kazuhito; Kawamata, Hiroshi; Kumazaki, Tatsuo

    1998-01-01

    Fat-suppressed, three-dimensional magnetic resonance angiography (3D MRA) was performed on nine patients with 11 iliac artery stenoses following atherectomy or stent placement. The MRA accurately depicted continued patency, restenosis, or aneurysm formation when compared with immediate posttreatment conventional arteriography. Therefore MRA is accurate and can be used independently for clinical decision making

  20. Assessment of renal artery stenosis of transplanted kidney by time resolved gadolinium-enhanced three-dimensional MR angiography. Preliminary phantom study and clinical evaluation

    International Nuclear Information System (INIS)

    Hayano, Toshio

    2001-01-01

    The purpose of this study was to determine a suitable imaging parameters of time-resolved Gd-enhanced three-dimensional MR angiography (TRE3DMRA) for the evaluation of renal artery stenosis of transplanted kidneys and to investigate the usefulness of TRE3DMRA in 166 clinical cases. Source images were obtained 3dFLASH with zero-filling interpolation (turbo MRA) using Siemens Magneton 1.5T. Acrylate tubes with 6 mm inner diameter filled with diluted Gd-DTPA were used as special phantoms. In the tubes, 25%, 50%, and 75% stenosis were made for simulating arterial stenosis, respectively. According to our clinical experiences, we decided 10 seconds or less acquisition time to obtaining renal artery images without overlapping with renal veins. To determine slice thickness, the degrees of stenosis of the phantom images obtained 8-second acquisition time in variable slice thickness were independently interpreted with visual inspection by two experienced diagnostic radiologists. One hundred sixty-six patients underwent renal transplantation were evaluated clinically. Using a power injector, 0.1 mmol/kg Gd-DTPA was injected after the test scan with 1 ml Gd-DTPA for the determination of acquisition timing. MR images were obtained in the following imaging parameters; 4-mm slice thickness and 8-second acquisition time based on the results of phantom studies. Source images were noted in oblique coronal direction encompassing the entire renal arteries from iliac arteries to renal hili. Based on phantom study, slice thickness must be less than 4-mm to demonstrate the significant stenotic portion (>50%) of the phantom simulating transplanted renal artery. In 150 of 166 patients, excellent images of renal arteries were obtained without overlapping with renal veins. Causes of poor images were mainly inadequate timing of image acquisition. We can decide the imaging parameters of TRE3DMRA for the evaluation of renal artery stenosis of transplanted kidneys. Using these parameters, in 150

  1. A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngjin, E-mail: radioyoungj@gmail.com [Department of Radiological Science, Eulji University, 553, Sanseong-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do (Korea, Republic of); Lee, Amy Candy [Department of Mathematics and Statistics, McGill University (Canada); Kim, Hee-Joung [Department of Radiological Science and Radiation Convergence Engineering, Yonsei University (Korea, Republic of)

    2016-09-11

    Recently, significant effort has been spent on the development of photons counting detector (PCD) based on a CdTe for applications in X-ray imaging system. The motivation of developing PCDs is higher image quality. Especially, the K-edge subtraction (KES) imaging technique using a PCD is able to improve image quality and useful for increasing the contrast resolution of a target material by utilizing contrast agent. Based on above-mentioned technique, we presented an idea for an improved K-edge log-subtraction (KELS) imaging technique. The KELS imaging technique based on the PCDs can be realized by using different subtraction energy width of the energy window. In this study, the effects of the KELS imaging technique and subtraction energy width of the energy window was investigated with respect to the contrast, standard deviation, and CNR with a Monte Carlo simulation. We simulated the PCD X-ray imaging system based on a CdTe and polymethylmethacrylate (PMMA) phantom which consists of the various iodine contrast agents. To acquired KELS images, images of the phantom using above and below the iodine contrast agent K-edge absorption energy (33.2 keV) have been acquired at different energy range. According to the results, the contrast and standard deviation were decreased, when subtraction energy width of the energy window is increased. Also, the CNR using a KELS imaging technique is higher than that of the images acquired by using whole energy range. Especially, the maximum differences of CNR between whole energy range and KELS images using a 1, 2, and 3 mm diameter iodine contrast agent were acquired 11.33, 8.73, and 8.29 times, respectively. Additionally, the optimum subtraction energy width of the energy window can be acquired at 5, 4, and 3 keV for the 1, 2, and 3 mm diameter iodine contrast agent, respectively. In conclusion, we successfully established an improved KELS imaging technique and optimized subtraction energy width of the energy window, and based on

  2. Synchrotron-based intravenous cerebral angiography in a small animal model

    International Nuclear Information System (INIS)

    Kelly, Michael E; Schueltke, Elisabeth; Fiedler, Stephan; Nemoz, Christian; Guzman, Raphael; Corde, Stephanie; Esteve, Francois; LeDuc, Geraldine; Juurlink, Bernhard H J; Meguro, Kotoo

    2007-01-01

    K-edge digital subtraction angiography (KEDSA), a recently developed synchrotron-based technique, utilizes monochromatic radiation and allows acquisition of high-quality angiography images after intravenous administration of contrast agent. We tested KEDSA for its suitability for intravenous cerebral angiography in an animal model. Adult male New Zealand rabbits were subjected to either angiography with conventional x-ray equipment or synchrotron-based intravenous KEDSA, using an iodine-based contrast agent. Angiography with conventional x-ray equipment after intra-arterial administration of contrast agent demonstrated the major intracranial vessels but no smaller branches. KEDSA was able to visualize the major intracranial vessels as well as smaller branches in both radiography mode (planar images) and tomography mode. Visualization was achieved with as little as 0.5 ml kg -1 of iodinated contrast material. We were able to obtain excellent visualization of the cerebral vasculature in an animal model using intravenous injection of contrast material, using synchrotron-based KEDSA

  3. Coronary CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Dewey, Marc [Charite - Universitaetsmedizin Berlin (Germany). Inst. fuer Radiologie

    2009-07-01

    Coronary CT angiography has attained increasing scientific attention at academic institutions and has become a highly accurate diagnostic modality. Extending this knowledge into a practice setting is the purpose of 'Coronary CT Angiography'. This book will assist you in integrating cardiac CT into your daily practice, while also giving an overview of the current technical status and applications. The specific features of scanners from all four main vendors are also presented providing an objective overview of noninvasive coronary angiography using CT. (orig.)

  4. Indications for coronary angiography

    International Nuclear Information System (INIS)

    Kaltenbach, M.; Vallbracht, C.

    1985-01-01

    Today selective coronary angiography, introduced by Sones in 1957, is used as clinical routine for diagnosing morphological changes in the coronary arteries. Hitherto, more recent techniques such as digital subtraction angiography cannot provide comparable information. Strict criteria for its indication depending on possible therapeutic consequences, have to be applied, although the risk is low with a letality of 0.01 to 0.05 percent. Radionuclear investigations can be used as additional tool in selected cases. The careful indication for coronary angiography usually implies the possible need for coronary bypass graft surgery of balloon angioplasty. (orig./MG) [de

  5. Structural disorder and electronic hybridization in NicMg1-cO solid solutions probed by XANES at the oxygen K edge

    International Nuclear Information System (INIS)

    Chen Dongliang; Zhong Jun; Chu Wangsheng; Wu Ziyu; Kuzmin, Alexei; Mironova-Ulmane, Nina; Marcelli, Augusto

    2007-01-01

    A series of Ni c Mg 1-c O solid solutions has been studied for the first time looking at the structural disorder by means of x-ray absorption near-edge-structure (XANES) spectroscopy at the oxygen K edge. The experimental XANES signals were analysed within the full multiple scattering formalism and were interpreted taking into account clusters of up to 15 coordination shells around an absorbing oxygen atom. The substitution of nickel atoms by magnesium atoms results in a dramatic decrease of the empty density of states in the conduction band close to the Fermi level due to an exchange of the 3d(Ni)-2p(O) interaction with 3p(Mg)-2p(O). Besides, a simultaneous small decrease of the 3d(Ni)-2p(O) hybridization is also induced by the lattice expansion, determined by the difference in ionic radii between nickel and magnesium ions

  6. Structural disorder and electronic hybridization in Ni{sub c}Mg{sub 1-c}O solid solutions probed by XANES at the oxygen K edge

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dongliang [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Zhong Jun [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Chu Wangsheng [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wu Ziyu [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Kuzmin, Alexei [Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Mironova-Ulmane, Nina [Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Marcelli, Augusto [Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, PO Box 13, 00044 Frascati (Italy)

    2007-09-05

    A series of Ni{sub c}Mg{sub 1-c}O solid solutions has been studied for the first time looking at the structural disorder by means of x-ray absorption near-edge-structure (XANES) spectroscopy at the oxygen K edge. The experimental XANES signals were analysed within the full multiple scattering formalism and were interpreted taking into account clusters of up to 15 coordination shells around an absorbing oxygen atom. The substitution of nickel atoms by magnesium atoms results in a dramatic decrease of the empty density of states in the conduction band close to the Fermi level due to an exchange of the 3d(Ni)-2p(O) interaction with 3p(Mg)-2p(O). Besides, a simultaneous small decrease of the 3d(Ni)-2p(O) hybridization is also induced by the lattice expansion, determined by the difference in ionic radii between nickel and magnesium ions.

  7. Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.; Marcelli, A.; Cibin, G. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Mottana, A. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Rome Univ. Roma Tre, Rome (Italy). Dipt. di Scienze Geologiche; Paris, E.; Giuli, G [INFM, Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra

    1999-07-01

    In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg end members F o and F a, and for three other olivines. Two are the Ca end members of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or {alpha}) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system.

  8. Optimization of the k-edge filters utilization in the dental radiographs; Otimizacao da utilizacao dos filtros de aresta K na radiografias dentarias

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, Luis M.G.; Almeida, Adelaide de [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica e Matematica

    2001-07-01

    The signal to noise ratio (S/N) of radiographic film images may be optimized if the thicknesses and atomic composition of the structures to be analyzed are known. With specifications and a knowledge of the interaction of photons with the materials, the photon energy for maximum contrast may be determined. We propose a K-edge filter in addition to the normal aluminum filter, to reduce the dose to the patient by the transmission of a narrow spectrum of photons with energies to optimize the image contrast. The optimum photon energy to obtain the best contrast between dental pulp and dentine and between dentine and dental enamel was determined to be 29-34 and 22-26 keV respectively. The filter material, which closely approximates these spectra, is made of Ce (Z=58) whose thickness is shown do depend on the parameters of the X-ray generator. (author)

  9. Pyrimidine and halogenated pyrimidines near edge x-ray absorption fine structure spectra at C and N K-edges: experiment and theory

    International Nuclear Information System (INIS)

    Bolognesi, P.; O'Keeffe, P.; Ovcharenko, Y.; Coreno, M.; Avaldi, L.; Feyer, V.; Plekan, O.; Prince, K. C.; Zhang, W.; Carravetta, V.

    2010-01-01

    The inner shell excitation of pyrimidine and some halogenated pyrimidines near the C and N K-edges has been investigated experimentally by near edge x-ray absorption fine structure spectroscopy and theoretically by density functional theory calculations. The selected targets, 5-Br-pyrimidine, 2-Br-pyrimidine, 2-Cl-pyrimidine, and 5-Br-2-Cl-pyrimidine, allow the effects of the functionalization of the pyrimidine ring to be studied either as a function of different halogen atoms bound to the same molecular site or as a function of the same halogen atom bound to different molecular sites. The results show that the individual characteristics of the different spectra of the substituted pyrimidines can be rationalized in terms of variations in electronic and geometrical structures of the molecule depending on the localization and the electronegativity of the substituent.

  10. Effect of atomic vibrations in XANES: polarization-dependent damping of the fine structure at the Cu K-edge of (creat)2CuCl4.

    Science.gov (United States)

    Šipr, Ondřej; Vackář, Jiří; Kuzmin, Alexei

    2016-11-01

    Polarization-dependent damping of the fine structure in the Cu K-edge spectrum of creatinium tetrachlorocuprate [(creat) 2 CuCl 4 ] in the X-ray absorption near-edge structure (XANES) region is shown to be due to atomic vibrations. These vibrations can be separated into two groups, depending on whether the respective atoms belong to the same molecular block; individual molecular blocks can be treated as semi-rigid entities while the mutual positions of these blocks are subject to large mean relative displacements. The effect of vibrations can be efficiently included in XANES calculations by using the same formula as for static systems but with a modified free-electron propagator which accounts for fluctuations in interatomic distances.

  11. Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

    International Nuclear Information System (INIS)

    Wu, Z.; Marcelli, A.; Cibin, G.; Mottana, A.; Rome Univ. Roma Tre, Rome; Paris, E.; Giuli, G.

    1999-01-01

    In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg endmembers F o and F a, and for three other olivines. Two are the Ca endmembers of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or α) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system

  12. Near K-edge measurement of the X-ray attenuation coefficient of heavy elements using a tuneable X-ray source based on an electron LINAC

    CERN Document Server

    Materna, T; Mondelaers, W; Masschaele, B

    2000-01-01

    The X-ray attenuation coefficients of bismuth and of uranium were measured in the regions of 40-240 and 70-240 keV, respectively, using a tuneable hard X-ray source based on the linear electron accelerator at the University of Ghent. Results were compared with the semi-empirical values of Storm and Israel and to the theoretical values of Berger and Hubbell. We also propose a simple function for the attenuation coefficient in the vicinity of the K-edge for uranium and in an extended range of energy for bismuth. The set-up of the source at Ghent is described and the future improvements are explained.

  13. Local structure in LaMnO3 and CaMnO3 perovskites: A quantitative structural refinement of Mn K-edge XANES data

    International Nuclear Information System (INIS)

    Monesi, C.; Meneghini, C.; Bardelli, F.; Benfatto, M.; Mobilio, S.; Manju, U.; Sarma, D.D.

    2005-01-01

    Hole-doped perovskites such as La 1-x Ca x MnO 3 present special magnetic and magnetotransport properties, and it is commonly accepted that the local atomic structure around Mn ions plays a crucial role in determining these peculiar features. Therefore experimental techniques directly probing the local atomic structure, like x-ray absorption spectroscopy (XAS), have been widely exploited to deeply understand the physics of these compounds. Quantitative XAS analysis usually concerns the extended region [extended x-ray absorption fine structure (EXAFS)] of the absorption spectra. The near-edge region [x-ray absorption near-edge spectroscopy (XANES)] of XAS spectra can provide detailed complementary information on the electronic structure and local atomic topology around the absorber. However, the complexity of the XANES analysis usually prevents a quantitative understanding of the data. This work exploits the recently developed MXAN code to achieve a quantitative structural refinement of the Mn K-edge XANES of LaMnO 3 and CaMnO 3 compounds; they are the end compounds of the doped manganite series La x Ca 1-x MnO 3 . The results derived from the EXAFS and XANES analyses are in good agreement, demonstrating that a quantitative picture of the local structure can be obtained from XANES in these crystalline compounds. Moreover, the quantitative XANES analysis provides topological information not directly achievable from EXAFS data analysis. This work demonstrates that combining the analysis of extended and near-edge regions of Mn K-edge XAS spectra could provide a complete and accurate description of Mn local atomic environment in these compounds

  14. Tetrahalide complexes of the [U(NR)2]2+ ion: synthesis, theory, and chlorine K-edge X-ray absorption spectroscopy.

    Science.gov (United States)

    Spencer, Liam P; Yang, Ping; Minasian, Stefan G; Jilek, Robert E; Batista, Enrique R; Boland, Kevin S; Boncella, James M; Conradson, Steven D; Clark, David L; Hayton, Trevor W; Kozimor, Stosh A; Martin, Richard L; MacInnes, Molly M; Olson, Angela C; Scott, Brian L; Shuh, David K; Wilkerson, Marianne P

    2013-02-13

    Synthetic routes to salts containing uranium bis-imido tetrahalide anions [U(NR)(2)X(4)](2-) (X = Cl(-), Br(-)) and non-coordinating NEt(4)(+) and PPh(4)(+) countercations are reported. In general, these compounds can be prepared from U(NR)(2)I(2)(THF)(x) (x = 2 and R = (t)Bu, Ph; x = 3 and R = Me) upon addition of excess halide. In addition to providing stable coordination complexes with Cl(-), the [U(NMe)(2)](2+) cation also reacts with Br(-) to form stable [NEt(4)](2)[U(NMe)(2)Br(4)] complexes. These materials were used as a platform to compare electronic structure and bonding in [U(NR)(2)](2+) with [UO(2)](2+). Specifically, Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT and TDDFT) were used to probe U-Cl bonding interactions in [PPh(4)](2)[U(N(t)Bu)(2)Cl(4)] and [PPh(4)](2)[UO(2)Cl(4)]. The DFT and XAS results show the total amount of Cl 3p character mixed with the U 5f orbitals was roughly 7-10% per U-Cl bond for both compounds, which shows that moving from oxo to imido has little effect on orbital mixing between the U 5f and equatorial Cl 3p orbitals. The results are presented in the context of recent Cl K-edge XAS and DFT studies on other hexavalent uranium chloride systems with fewer oxo or imido ligands.

  15. Angiography - interventional diagnostic applications

    International Nuclear Information System (INIS)

    Schild, H.

    1994-01-01

    The angiography system is very different from the other systems used in diagnostic radiology. The invasivity of angiography requires special, high standards in theoretical and practical training and experience both of beginners and experienced personnel. This textbook fully meets the demand for in-depth and exhaustive information, as it presents: - The fundamentals and techniques of angiography, the vascular anatomy, and many hints and tips of great help in practice. - A comprehensive survey of diagnostic problems and examination approaches, including neuro-angiography, with 221 reproductions of original angiographs, and additional schematic representations. - A special chapter devoted to indication and relevant techniques for the major vascular interventional examinations. - A great number of tables explain at a glance standard examination techniques, indications and diagnostic criteria. (orig./CB) [de

  16. Angiography in portal hypertension

    Energy Technology Data Exchange (ETDEWEB)

    Zeitler, E

    1982-04-05

    We report on the cooperative possibilities the radiologist has as to diagnosis and therapy of portal hypertension. The catheter angiography allows to make a differentiation between pre- and intrahepatic bloc and the localization of bleeding esophagus varices. Only after all endoscopic measures with sclerotherapy and Laser coagulation have failed, catheter angiography will be carried out as a therapeutic measure. The future development, however, will give the opportunity to a series of therapeutic attempts on the field of interventional radiology.

  17. Angiography in portal hypertension

    International Nuclear Information System (INIS)

    Zeitler, E.

    1982-01-01

    We report on the cooperative possibilities the radiologist has as to diagnosis and therapy of portal hypertension. The catheter angiography allows to make a differentiation between pre- and intrahepatic bloc and the localization of bleeding esophagus varices. Only after all endoscopic measures with sclerotherapy and Laser coagulation have failed, catheter angiography will be carried out as a therapeutic measure. The future development, however, will give the opportunity to a series of therapeutic attempts on the field of interventional radiology. (orig.) [de

  18. Pediatric CT angiography

    International Nuclear Information System (INIS)

    Siegel, M.J.

    2005-01-01

    Advances in CT technology are having profound impact on imaging children and have made CT angiography possible even in neonates. Even with the tiny anatomy of neonates, small volumes of contrast material, and small venous access catheters, successful CT angiography can be performed with attention to detail. Meticulous attention to patient preparation, the proper selection of technical factors, and optimal delivery of contrast material are crucial. Data post-processing and the creation of 3-D reconstructions are also essential in establishing a correct diagnosis. The applications fo CT angiography are different in children than in adults and most applications in children involve assessment of congenital and postoperative vascular and cardiac diseases. The use of CT angiography offers the opportunity to eliminate the long periods of sedation associated with MR and reduce the radiation exposure associated with conventional angiography. Generally, the benefits of CT angiography in children outweigh the risk, namely that of radiation exposure. However, care must still be taken to minimize the radiation exposure. (orig.)

  19. WE-FG-207B-01: BEST IN PHYSICS (IMAGING): Abdominal CT with Three K-Edge Contrast Materials Using a Whole-Body Photon-Counting Scanner: Initial Results of a Large Animal Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmanan, M; Symons, R; Cork, T; Davies-Venn, C; Rice, K; Malayeri, A; Sandfort, V; Bluemke, D; Pourmorteza, A [National Institutes of Health Clinical Center, Bethesda, MD (United States)

    2016-06-15

    Purpose: To demonstrate the feasibility of in vivo three-material decomposition techniques using photon-counting CT (PCCT) with possible advantage of resolving arterial and venous flow of an organ simultaneously. Methods: Abdominal PCCT scans were acquired using a prototype whole-body PCCT with four energy thresholds (25/50/75/90keV) in a canine. Bismuth subsalicylate (60 mg) was administered orally one day prior to scanning. Immediately prior to CT scan, gadoteric acid (60 ml, Dotarem, Guerbet) was intravenously injected, followed in ten minutes by a 20mL injection of iodinated contrast (iopamidol 370 mg/mL, Bracco). Scans were acquired every ∼20 seconds, starting from the time of iodine injection. Linear material decomposition was performed using the least mean squares method to create concentration maps of iodine, gadolinium, and bismuth. The method was calibrated to vials with known concentrations of materials placed next to the animal. The accuracy of this method was tested on vials with known concentrations. Results: The material decomposition algorithm’s accuracy was confirmed to be within ±4mM in the test vials. In the animal, we could estimate the concentration of gadolinium in delayed-enhanced phase (10 minutes post-injection) in the abdomen. We could follow the wash-in and wash-out of iodine in arterial, venous, and excretory flow of the kidneys (20s, 80s, and 120s post-iodine injection) while gadolinium was present in the delayed-enhanced phase. Bismuth, which was used as a contrast agent for the gastro-intestinal tract, was easily differentiable from the other two contrast agents in the small intestine. Conclusion: This study shows the feasibility of using photon-counting CT with four energy thresholds to differentiate three k-edge contrast agents in vivo. This can potentially reduce radiation dose to patients by combining arterial and venous phases into a single acquisition.

  20. Subtraction MR venography acquired from time-resolved contrast-enhanced MR angiography: Comparison with phase-contrast MR venography and single-phase contrast-enhanced MR venography

    International Nuclear Information System (INIS)

    Jang, Jin Hee; Kim, Bum Soo; KIm, Bom Yi; Choi, Hyun Seok; Jung, So Lyung; Ahn, Kook Jin; Sung, Ji Kyeong

    2015-01-01

    To evaluate the image characteristics of subtraction magnetic resonance venography (SMRV) from time-resolved contrast-enhanced MR angiography (TRMRA) compared with phase-contrast MR venography (PCMRV) and single-phase contrast-enhanced MR venography (CEMRV). Twenty-one patients who underwent brain MR venography (MRV) using standard protocols (PCMRV, CEMRV, and TRMRA) were included. SMRV was made by subtracting the arterial phase data from the venous phase data in TRMRA. Co-registration and subtraction of the two volume data was done using commercially available software. Image quality and the degree of arterial contamination of the three MRVs were compared. In the three MRVs, 19 pre-defined venous structures (14 dural sinuses and 5 cerebral veins) were evaluated. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the three MRVs were also compared. Single-phase contrast-enhanced MR venography showed better image quality (median score 4 in both reviewers) than did the other two MRVs (p < 0.001), whereas SMRV (median score 3 in both reviewers) and PCMRV (median score 3 in both reviewers) had similar image quality (p ≥ 0.951). SMRV (median score 0 in both reviewers) suppressed arterial signal better than did the other MRVs (median score 1 in CEMRV, median score 2 in PCMRV, both reviewers) (p < 0.001). The dural sinus score of SMRV (median and interquartile range [IQR] 48, 43-50 for reviewer 1, 47, 43-49 for reviewer 2) was significantly higher than for PCMRV (median and IQR 31, 25-34 for reviewer 1, 30, 23-32 for reviewer 2) (p < 0.01) and did not differ from that of CEMRV (median and IQR 50, 47-52 for reviewer 1, 49, 45-51 for reviewer 2) (p = 0.146 in reviewer 1 and 0.123 in reviewer 2). The SNR and CNR of SMRV (median and IQR 104.5, 83.1-121.2 and 104.1, 74.9-120.5, respectively) were between those of CEMRV (median and IQR 150.3, 111-182.6 and 148.4, 108-178.2) and PCMRV (median and IQR 59.4, 49.2-74.9 and 53.6, 43.8-69.2). Subtraction magnetic

  1. Intracranial MR angiography

    International Nuclear Information System (INIS)

    Davis, W.L.; Blatter, D.D.; Parker, D.L.; Robison, R.O.; Harnsberger, H.R.

    1991-01-01

    This paper compares the more traditional three-dimensional (3D) time-of-flight MR angiography with a novel new technique, MOTSA, in the evaluation of both normal and abnormal intracranial anatomy. The authors performed sequential, location-matched 3D TOF and MOTSA MR angiography in 10 subjects with normal and 25 with abnormal intracranial anatomy. Images were evaluated for visualization of specific vessels and depiction of pathologic anatomy. All images were subjected to an objective scoring system. Digital angiography was available in 15 of 25 abnormal cases. In the normal cases, large- and small-vessel visualization was improved. Significant improvement in visualization of venous anatomy was also observed. In the abnormal cases, pathologic anatomy was better visualized, providing important diagnostic information. Multiple overlapping thin-slab-acquisition MR angiography demonstrates vessel visualization that is increased over that of 3D TOF MR angiography in both normal and abnormal cases. Because of the decrease in saturation effects and phase dispersion, MOTSA is especially useful in the evaluation of complex intracranial vascular abnormalities

  2. First-Principles Fe L 2,3 -Edge and O K-Edge XANES and XMCD Spectra for Iron Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Sassi, Michel [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Pearce, Carolyn I. [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Bagus, Paul S. [Department; Arenholz, Elke [Advanced; Rosso, Kevin M. [Pacific Northwest National Laboratory, Richland, Washington 99352, United States

    2017-10-02

    X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) spectroscopies are tools in widespread use for providing detailed local atomic structure, oxidation state, and magnetic structure information for materials and organometallic complexes. The analysis of these spectra for transition-metal L-edges is routinely performed on the basis of ligand-field multiplet theory because one- and two-particle mean-field ab initio methods typically cannot describe the multiplet structure. Here we show that multireference configuration interaction (MRCI) calculations can satisfactorily reproduce measured XANES spectra for a range of complex iron oxide materials including hematite and magnetite. MRCI Fe L2,3-edge XANES and XMCD spectra of Fe(II)O6, Fe(III)O6, and Fe(III)O4 in magnetite are found to be in very good qualitative agreement with experiment and multiplet calculations. Point-charge embedding and small distortions of the first-shell oxygen ligands have only small effects. Oxygen K-edge XANES/XMCD spectra for magnetite investigated by a real-space Green’s function approach complete the very good qualitative agreement with experiment. Material-specific differences in local coordination and site symmetry are well reproduced, making the approach useful for assigning spectral features to specific oxidation states and coordination environments.

  3. Evolution of phosphorus complexation and mineralogy during (hydro)thermal treatments of activated and anaerobically digested sludge: Insights from sequential extraction and P K-edge XANES.

    Science.gov (United States)

    Huang, Rixiang; Tang, Yuanzhi

    2016-09-01

    (Hydro)thermal treatments of sewage sludge is a promising option that can simultaneously target safe waste disposal, energy recovery, and nutrient recovery/recycling. The speciation of phosphorus (P) in sludge is of great relevance to P reclamation/recycling and soil application of sludge-derived products, thus it is critical to understand the effects of different treatment techniques and conditions on P speciation. This study systematically characterized P speciation (i.e. complexation and mineral forms) in chars derived from pyrolysis and hydrothermal carbonization (HTC) of municipal sewage sludges. Combined sequential extraction and P K-edge X-ray absorption near edge structure (XANES) spectroscopy analysis revealed the dependence of P transformation on treatment conditions and metal composition in the feedstocks. Pyrolysis of sludges decreased the relative abundance of phytic acid while increased the abundance of Al-associated P. HTC thoroughly homogenized and exposed P for interaction with various metals/minerals, with the final P speciation closely related to the composition/speciation of metals and their affinities to P. Results from this study revealed the mechanisms of P transformation during (hydro)thermal treatments of sewage sludges, and might be applicable to other biosolids. It also provided fundamental knowledge basis for the design and selection of waste management strategies for better P (re)cycling and reclamation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Hydrogen bonding interaction of small acetaldehyde clusters studied with core-electron excitation spectroscopy in the oxygen K-edge region

    Science.gov (United States)

    Tabayashi, K.; Chohda, M.; Yamanaka, T.; Tsutsumi, Y.; Takahashi, O.; Yoshida, H.; Taniguchi, M.

    2010-06-01

    In order to examine inner-shell electron excitation spectra of molecular clusters with strong multipole interactions, excitation spectra and time-of-flight (TOF) fragment-mass spectra of small acetaldehyde (AA) clusters have been studied under the beam conditions. The TOF spectra at the oxygen K-edge region showed an intense growth of the protonated clusters, MnH+ (M=CH3CHO) in the cluster beams. "cluster-specific" excitation spectra could be generated by monitoring partial-ion-yields of the protonated clusters. The most intense band of O1s→π*CO was found to shift to a higher energy by 0.15 eV relative to the monomer band upon clusterization. X-ray absorption spectra (XAS) were also calculated for the representative dimer configurations using a computer modelling program based on the density functional theory. The XAS prediction for the most stable (non-planar) configuration was found to give a close comparison with the cluster-band shift observed. The band shift was interpreted as being due to the HOMO-LUMO interaction within the complex where a contribution of vibrationally blue-shifting hydrogen bonding could be identified.

  5. Organometallic model complexes elucidate the active gallium species in alkane dehydrogenation catalysts based on ligand effects in Ga K-edge XANES

    Energy Technology Data Exchange (ETDEWEB)

    Getsoian, Andrew “Bean”; Das, Ujjal; Camacho-Bunquin, Jeffrey; Zhang, Guanghui; Gallagher, James R.; Hu, Bo; Cheah, Singfoong; Schaidle, Joshua A.; Ruddy, Daniel A.; Hensley, Jesse E.; Krause, Theodore R.; Curtiss, Larry A.; Miller, Jeffrey T.; Hock, Adam S.

    2016-01-01

    Gallium-modified zeolites are known catalysts for the dehydrogenation of alkanes, reactivity that finds industrial application in the aromatization of light alkanes by Ga-ZSM5. While the role of gallium cations in alkane activation is well known, the oxidation state and coordination environment of gallium under reaction conditions has been the subject of debate. Edge shifts in Ga K-edge XANES spectra acquired under reaction conditions have long been interpreted as evidence for reduction of Ga(III) to Ga(I). However, a change in oxidation state is not the only factor that can give rise to a change in the XANES spectrum. In order to better understand the XANES spectra of working catalysts, we have synthesized a series of molecular model compounds and grafted surface organometallic Ga species and compared their XANES spectra to those of gallium-based catalysts acquired under reducing conditions. We demonstrate that changes in the identity and number of gallium nearest neighbors can give rise to changes in XANES spectra similar to those attributed in literature to changes in oxidation state. Specifically, spectral features previously attributed to Ga(I) may be equally well interpreted as evidence for low-coordinate Ga(III) alkyl or hydride species. These findings apply both to gallium-impregnated zeolite catalysts and to silica-supported single site gallium catalysts, the latter of which is found to be active and selective for dehydrogenation of propane and hydrogenation of propylene.

  6. X-ray absorption study at the Mg and O K edges of ultrathin MgO epilayers on Ag(001)

    International Nuclear Information System (INIS)

    Luches, P.; D'Addato, S.; Valeri, S.; Groppo, E.; Prestipino, C.; Lamberti, C.; Boscherini, F.

    2004-01-01

    We determined the local atomic structure of MgO epilayers on Ag(001) by means of polarization-dependent x-ray absorption spectroscopy measurements at the Mg and O K edges. A quantitative analysis of the data in the extended energy range has been performed using multiple scattering simulations. We found that, even in the ultrathin limit, the local structure of the films is rocksalt and we obtained a quantitative evaluation of the average in-plane and out-of-plane film strain at the different thicknesses investigated. An in-plane compressive strain, due to lattice mismatch with the Ag substrate, is clearly present for the 3 ML film. The out-of-plane lattice constant is found to be expanded, in agreement with the expected behavior for a tetragonal distortion of the unit cell. This growth-induced strain is gradually released with increasing thickness and it is almost completely relaxed at 20 ML. Any significant intermixing with the Ag substrate can be ruled out. An expansion of the interplanar distance at the MgO-Ag interface is detected and its sign and magnitude are found to be in agreement with recent ab initio simulations. This work provides previously unavailable input for modeling the physical properties of the system and supports the hypothesis that the different electronic properties of MgO films on Ag(001) are not related to structural or compositional differences at the ultrathin limit

  7. Surface structure of alpha-Fe sub 2 O sub 3 nanocrystal observed by O K-edge X-ray absorption spectroscopy

    CERN Document Server

    Zhang, J; Ibrahim, K; Abbas, M I; Ju, X

    2003-01-01

    X-ray absorption near edge structure (XANES) spectra is used as a probe of surface structure of alpha-Fe sub 2 O sub 3 nanocrystal, prepared by sol-gel method. We present O K-edge XANES of alpha-Fe sub 2 O sub 3 in nanocrystal and bulk by total electron yield at the photoemission station of Beijing Synchrotron Radiation Facility. The spectrum of alpha-Fe sub 2 O sub 3 shows a splitting of the pre-edge structure, which is interpreted as two subsets of Fe 3d t sub 2 sub g and e sub g orbitals in oxygen octahedral (O sub h) crystal field, and is also sensitive to long-range order effects. However, no distinguishable splitting of the pre-edge peak of nanocrystal alpha-Fe sub 2 O sub 3 is observed. This suggests that there exists the distorted octahedral coordination around Fe sites and also the long-range disorder due to the surface as compared with bulk alpha-Fe sub 2 O sub 3.

  8. Redox Reaction in Silicate Melts Monitored by ''Static'' In-Situ Fe K-Edge XANES up to 1180 deg. C

    International Nuclear Information System (INIS)

    Wilke, Max; Partzsch, Georg M.; Welter, Edmund; Farges, Francois

    2007-01-01

    A new experimental setup to measure in-situ kinetics of redox reactions in silicate melts is presented. To study the progress of the Fe-redox reaction, the variation of the signal is recorded at an energy, where the difference between the spectra of the oxidized and reduced Fe in the melt is largest (''static XANES''). To control the redox conditions, the gas atmosphere could be changed between to types of gases using computer-controlled valves (N2:H2 and air, respectively). In this way, a number of reduction/oxidation cycles can be monitored in-situ and continuously. Applied at the Fe K-edge in molten silicates, we obtained a set of high quality data, which includes the very first steps of the redox reaction. An Avrami-type equation is used to investigate rate-controlling parameters for the iron oxidation/reduction kinetics for two melts (basaltic and Na trisilicate) for temperatures up to 1180 deg. C

  9. UV-Photochemistry of the Disulfide Bond: Evolution of Early Photoproducts from Picosecond X-ray Absorption Spectroscopy at the Sulfur K-Edge.

    Science.gov (United States)

    Ochmann, Miguel; Hussain, Abid; von Ahnen, Inga; Cordones, Amy A; Hong, Kiryong; Lee, Jae Hyuk; Ma, Rory; Adamczyk, Katrin; Kim, Tae Kyu; Schoenlein, Robert W; Vendrell, Oriol; Huse, Nils

    2018-05-30

    We have investigated dimethyl disulfide as the basic moiety for understanding the photochemistry of disulfide bonds, which are central to a broad range of biochemical processes. Picosecond time-resolved X-ray absorption spectroscopy at the sulfur K-edge provides unique element-specific insight into the photochemistry of the disulfide bond initiated by 267 nm femtosecond pulses. We observe a broad but distinct transient induced absorption spectrum which recovers on at least two time scales in the nanosecond range. We employed RASSCF electronic structure calculations to simulate the sulfur-1s transitions of multiple possible chemical species, and identified the methylthiyl and methylperthiyl radicals as the primary reaction products. In addition, we identify disulfur and the CH 2 S thione as the secondary reaction products of the perthiyl radical that are most likely to explain the observed spectral and kinetic signatures of our experiment. Our study underscores the importance of elemental specificity and the potential of time-resolved X-ray spectroscopy to identify short-lived reaction products in complex reaction schemes that underlie the rich photochemistry of disulfide systems.

  10. Study of apical oxygen atoms in a spin-ladder cuprate compound by X-ray absorption spectroscopy near the Cu K edge

    Energy Technology Data Exchange (ETDEWEB)

    Hatterer, C.J.; Eustache, B.; Collin, L.; Beuran, C.F.; Partiot, C.; Germain, P.; Xu, X.Z.; Lagues, M. [CNRS, Paris (France). Surfaces et Supraconducteurs; Michalowicz, A. [Laboratoire de Physique des Milieux Desordonnes, Universite Paris XII Val-de-Marne, 61 avenue du general de Gaulle, 94010, Creteil Cedex (France)]|[LURE, Universite Paris Sud, 91405, Orsay Cedex (France); Moscovici, J. [Laboratoire de Physique des Milieux Desordonnes, Universite Paris XII Val-de-Marne, 61 avenue du general de Gaulle, 94010, Creteil Cedex (France); Deville Cavellin, C. [CNRS, Paris (France). Surfaces et Supraconducteurs]|[Laboratoire d`Electronique, Universite Paris XII Val-de-Marne, 61 av. du general de Gaulle, 94010, Creteil Cedex (France); Traverse, A. [LURE, Universite Paris Sud, 91405, Orsay Cedex (France)

    1997-04-01

    The structure of high-T{sub c} superconducting cuprate compounds is based on CuO{sub 2} planes alternating with blocks that behave as charge reservoirs. The apical oxygen atoms which belong to these reservoirs are suspected to play a role in the mechanism of superconductivity. It thus seems necessary to measure the amount of apical oxygen atoms in various compounds, as a function of the superconducting properties. Polarisation dependent X-ray absorption spectroscopy (XAS) measurements were performed near the Cu K-edge on three types of phases. We collected information about the neighbourhood of the copper atom in the cuprate planes and in the direction perpendicular to these planes. Two of these phases have well known structures: Bi2212 in which copper atoms are on a pyramidal site and infinite layer phase, a square planar cuprate without apical oxygen. We used the obtained results as reference data to study a new copper-rich phase related to the spin-ladder series. (orig.)

  11. Contrast-enhanced three-dimensional magnetic resonance angiography of the aorta and its branches. Clinical applications for a new angiographic technique

    International Nuclear Information System (INIS)

    Dolz, J. L.; Vilanova, J. C.; Huguet, M.; Delgado, E.; Baquero, M.; Blanch, A.; Aldoma, J.; Capdevila, A.

    1999-01-01

    Magnetic resonance angiography (MRA) for the study of the aorta has developed at an impressive rate in recent years. It is now possible to evaluate the aorta and its branches by means of magnetic resonance (MR) following administration via peripheral vein of a paramagnetic contrast agent. The approach is similar to that of conventional arteriography, but without the risk associated with iodinated contrast media or invasive arterial catheterization. The technique involves the use of a sequence of ultrafast three-dimensional gradient-echo pulses acquired during apnea. This process enables angiographic or volumetric visualization in the desired plane. The objective of the present report is to describe the technique and demonstrate its many clinical applications. (Author) 23 refs

  12. MR angiography (MRA)

    Energy Technology Data Exchange (ETDEWEB)

    Hasuo, Kanehiro [Kyushu Univ., Fukuoka (Japan). Faculty of Medicine

    1995-12-01

    The primary goal of vascular imaging is the visualization of morphology and hemodynamics. Catheter angiography has been regarded as a gold standard for this purpose. However, MR angiography (MRA) is now increasingly being recognized as an important noninvasive technique for the depiction of vascular diseases and is partially superseding catheter angiography. The author evaluated the usefulness of MRA in the diagnosis of cerebral aneurysms and moyamoya disease. All aneurysms 5 mm or larger in diameter could be detected and most of those less than 5 mm in diameter were also detectable with using a combination of MIP images, target MIP images and source images. In moyamoya disease, the diagnosis could be made in all. For hemodynamic changes, flow directions in the circle of Willis could be visualized by phase-contrast MRA in a normal volunteer. In addition, MRA successfully showed the patency of surgical collaterals in cases of moyamoya disease. Despite some limitations compared with catheter angiography, MRA has a high sensitivity and specificity in the diagnosis of cerebrovascular abnormalities. Furthermore, screening of cerebral aneurysms or cerebrovascular occlusive diseases seems to be a new, and important indication for MRA. (author).

  13. Local Environment Sensitivity of the Cu K-Edge XANES Features in Cu-SSZ-13: Analysis from First-Principles.

    Science.gov (United States)

    Zhang, Renqin; McEwen, Jean-Sabin

    2018-05-22

    Cu K-edge X-ray absorption near-edge spectra (XANES) have been widely used to study the properties of Cu-SSZ-13. In this Letter, the sensitivity of the XANES features to the local environment for a Cu + cation with a linear configuration and a Cu 2+ cation with a square-linear configuration in Cu-SSZ-13 is reported. When a Cu + cation is bonded to H 2 O or NH 3 in a linear configuration, the XANES has a strong peak at around 8983 eV. The intensity of this peak decreases as the linear configuration is broken. As for the Cu 2+ cations in a square-planar configuration with a coordination number of 4, two peaks at around 8986 and 8993 eV are found. An intensity decrease for both peaks at around 8986 and 8993 eV is found in an NH 3 _4_Z 2 Cu model as the N-Cu-N angle changes from 180 to 100°. We correlate these features to the variation of the 4p state by PDOS analysis. In addition, the feature peaks for both the Cu + cation and Cu 2+ cation do not show a dependence on the Cu-N bond length. We further show that the feature peaks also change when the coordination number of the Cu cation is varied, while these feature peaks are independent of the zeolite topology. These findings help elucidate the experimental XANES features at an atomic and an electronic level.

  14. Trace metal analysis by laser ablation-inductively coupled plasmamass spectrometry and x-ray K-edge densitometry of forensic samples

    Energy Technology Data Exchange (ETDEWEB)

    Berry, Jonna Elizabeth [Iowa State Univ., Ames, IA (United States)

    2016-10-25

    This dissertation describes a variety of studies on the determination of trace elements in samples with forensic importance. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to determine the trace element composition of numerous lipstick samples. Lipstick samples were determined to be homogeneous. Most lipstick samples of similar colors were readily distinguishable at a 95% confidence interval based on trace element composition. Numerous strands of a multi-strand speaker cable were analyzed by LA-ICP-MS. The strands in this study are spatially heterogeneous in trace element composition. In actual forensic applications, the possibility of spatial heterogeneity must be considered, especially in cases where only small samples (e.g., copper wire fragments after an explosion) are available. The effects of many unpredictable variables, such as weather, temperature, and human activity, on the retention of gunshot residue (GSR) around projectile wounds were assessed with LAICP- MS. Skin samples around gunshot and stab wounds and larvae feeding in and around the wounds on decomposing pig carcasses were analyzed for elements consistent with GSR (Sb, Pb, Ba, and Cu). These elements were detected at higher levels in skin and larvae samples around the gunshot wounds compared to the stab wounds for an extended period of time throughout decomposition in both a winter and summer study. After decomposition, radiographic images of the pig bones containing possible damage from bullets revealed metallic particles embedded within a number of bones. Metallic particles within the bones were analyzed with x-ray, K-edge densitometry and determined to contain lead, indicating that bullet residue can be retained throughout decomposition and detected within bones containing projectile trauma.

  15. X-ray absorption near edge spectroscopy at the Mn K-edge in highly homogeneous GaMnN diluted magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Sancho-Juan, O.; Cantarero, A.; Garro, N.; Cros, A. [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Martinez-Criado, G.; Salome, M.; Susini, J. [ESRF, Polygone Scientifique Louis Neel, 6 rue Jules Horowitz, 38000 Grenoble (France); Olguin, D. [Dept. de Fisica, CINVESTAV-IPN, 07300 Mexico D.F. (Mexico); Dhar, S.; Ploog, K. [Paul Drude Institute, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2006-06-15

    We have studied by X-ray absorption spectroscopy the local environment of Mn in highly homogeneous Ga{sub 1-x}Mn{sub x}N (0.06K-edges. In this report, we focus our attention to the X-ray absorption near edge spectroscopy (XANES) results. The comparison of the XANES spectra corresponding to the Ga and Mn edges indicates that Mn is substitutional to Ga in all samples studied. The XANES spectra measured at the Mn absorption edge shows in the near-edge region a double peak and a shoulder below the absorption edge and the main absorption peak after the edge, separated around 15 eV above the pre-edge structure. We have compared the position of the edge with that of MnO (Mn{sup 2+}) and Mn{sub 2}O{sub 3} (Mn{sup 3+}). All samples studied present the same Mn oxidation state, 2{sup +}. In order to interprete the near-edge structure, we have performed ab initio calculations with a 2 x 2 x 1supercell ({proportional_to}6% Mn) using the full potential linear augmented plane wave method as implemented in the Wien2k code. The calculations show the appearance of Mn anti-bonding t{sub 2g} bands, which are responsible for the pre-edge absorption. The shoulder and main absorption peaks are due to transitions from the valence band 1s-states of Mn to the p-contributions of the conduction bands. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Coronary MR angiography: current status

    International Nuclear Information System (INIS)

    Danias, P.G.; Manning, W.J.

    2000-01-01

    Since first described in the early 1990s, coronary magnetic resonance angiography (MRA) has evolved as a promising noninvasive modality for imaging of the coronary arteries and evaluation of coronary artery disease. Despite technical limitations, coronary MRA has established value for imaging of anomalous coronary arteries and assessment of bypass graft patency. Current research focuses on the development of optimal respiratory compensation strategies, improved spatial and temporal resolution and faster acquisition of image data. The accurate detection of stenoses and assessment of the severity of coronary atherosclerosis is presently being evaluated with large multi-center studies. With further technique enhancements and more clinical experience, coronary MRA is likely to become the dominant noninvasive modality in clinical cardiology. (orig.) [de

  17. Contrast Enhancement in TOF cerebral angiography at 7 T using Saturation and MT pulses under SAR constraints: impact of VERSE and sparse pulses

    Science.gov (United States)

    Schmitter, Sebastian; Bock, Michael; Johst, Sören; Auerbach, Edward J.; Uğurbil, Kâmil; Van de Moortele, Pierre-François

    2011-01-01

    Cerebral 3D time of flight (TOF) angiography significantly benefits from ultra high fields, mainly due to higher SNR and to longer T1 relaxation time of static brain tissues, however, SAR significantly increases with B0. Thus, additional RF pulses commonly used at lower field strengths to improve TOF contrast such as saturation of venous signal and improved background suppression by magnetization transfer typically cannot be used at higher fields. In this work we aimed at reducing SAR for each RF pulse category in a TOF sequence. We use the VERSE principle for the slab selective TOF excitation as well as the venous saturation RF pulses. Additionally, MT pulses are implemented by sparsely applying the pulses only during acquisition of the central k-space lines to limit their SAR contribution. Image quality, angiographic contrast and SAR reduction were investigated as a function of VERSE parameters and of the total number of MT pulses applied. Based on these results, a TOF protocol was generated that increases the angiographic contrast by more than 50% and reduces subcutaneous fat signal while keeping the resulting SAR within regulatory limits. PMID:22139829

  18. CT and MR angiography

    International Nuclear Information System (INIS)

    Bert, A.L.; Marshal, G.

    1995-01-01

    CT-angiography is a new vessel imaging technique based on the volumetric scanning of the region of interst during the first pass of IV bolus injection of contrast medium. MR-angiography is a titally noninvasive technique. The differentiation of flowing blood from the adjecent stationary tissues is based on the detection of blood motion. The flowing blood is highlighted with white light. CT- and MR-angiographic techniques are used to establish% stenoses and occlusions in intracranial arteries; aneurisms; trombosis of intracranial veins and venous angioma; diseases of neck vessels, thoracic vessels, abdominal vessels. Blood flow direction in cirrotic patients with portal hypertension can be determined in the portal vein, as well as the presence of thrombosis

  19. Angiography in renal tuberculosis

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Doo Suk [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1974-10-15

    Angiographies on forty cases of renal tuberculosis performed at the National Medical Center during a period 1960 through 1970 were reviewed. Abdominal angiography was performed via the femoral route. Some were followed by selective nephroangiography. All patients were subjected to urographyior to angiography. The results of X-ray findings in the forty cases with renal tuberculosis were follows. 1. The age varied 18 to 57 years, average 30.5 years. Twenty one patients were male, and nineteen were female. 2. The right kidney was involved in 17 cases and the left in 15 cases. Both kidneys were involved in 8 cases. 3. Urographic examination revealed pathologic changes in all patients. 4. Focal destruction in the collecting system was the most common finding in the urography of 16 patients. 5. A varying degree of hydronephrosis was present in 15 patients, of whom nine had complained of palpable mass due to hydronephrosis. 6. In the 7 patients with extensive destruction there was no observable excretion contrast medium from the diseased kidney. 7. Angiographic examination was normal in 6 of the 40 patients. 8. Decreased vascularity in the subsegmental or smaller arteries of the affected kidney was the most frequent finding, being found in 34 patients. 9. Occlusion or abrupt termination of the subsegmental arteries was present in 4 patients. 10. Eighteen of the patients had signs of an expansive process within the cavity, the vessels being displaced and stretched around the lesions.

  20. MDCT angiography of the pulmonary arteries: intravascular contrast enhancement does not depend on iodine concentration when injecting equal amounts of iodine at standardized iodine delivery rates

    International Nuclear Information System (INIS)

    Keil, S.; Plumhans, C.; Behrendt, F.F.; Das, M.; Muehlenbruch, G.; Mahnken, A.H.; Guenther, R.W.; Stanzel, S.; Seidensticker, P.; Knackstedt, C.; Wildberger, J.E.

    2008-01-01

    To compare the impact of iodine concentration using two different contrast materials (CM) at standardized iodine delivery rate (IDR) and overall iodine load in 16-multidetector-row-CT-angiography (MDCTA) of the pulmonary arteries of 192 patients with known or suspected pulmonary embolism. One hundred three patients (group A) received 148 ml of a CM containing 300 mg iodine/ml (Ultravist 300 trademark, BayerScheringPharma) at a flow rate of 4.9 ml/s. Eighty-nine patients (group B) received 120 ml of a CM with a concentration of 370 mg iodine/ml (Ultravist370 trademark) at a flow rate of 4.0 ml/s, resulting in a standardized IDR (∝1.5 gI/s) and the same overall amount of iodine (44.4 g). Both CM injections were followed by a saline chaser. Mean density values were determined in the pulmonary trunk, the ascending and the descending aorta, respectively. Applying repeated-measures ANOVA, no statistically significant differences between both MDCTA protocols were found (p=0.5790): the mean density in the pulmonary trunk was 355±116 Hounsfield Units (group A) and 358±115 (group B). The corresponding values for the ascending and descending aorta were 295±79 (group A) and 284±65 (group B) as well as 272±71 and 262±70. In conclusion, the use of standardized IDR and overall iodine load provides comparable intravascular CM density in pulmonary 16-MDCTA for delivering contrast materials with different iodine concentrations. (orig.)

  1. Angiography and the gastrointestinal bleeder

    International Nuclear Information System (INIS)

    Baum, S.

    1982-01-01

    The role of angiography in the diagnosis and treatment of gastrointestinal hemorrhage is discussed. Three categories of gastrointestinal bleeding are considered: upper gastrointestinal bleeding due to gastroesophageal varices, upper gastrointestinal bleeding of arterial or capillary origin, and lower gastrointestinal bleeding. The advantages and disadvantages of angiography are compared with those of radionuclide scanning and endoscopy or colonoscopy. It is anticipated that, as radionuclide scans are more widely employed, angiography will eventually be performed only in those patients with positive scans

  2. Triple Arterial Phase MR Imaging with Gadoxetic Acid Using a Combination of Contrast Enhanced Time Robust Angiography, Keyhole, and Viewsharing Techniques and Two-Dimensional Parallel Imaging in Comparison with Conventional Single Arterial Phase

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jeong Hee [Department of Radiology, Seoul National University Hospital, Seoul 03080 (Korea, Republic of); Department of Radiology, Seoul National University College of Medicine, Seoul 03087 (Korea, Republic of); Lee, Jeong Min [Department of Radiology, Seoul National University Hospital, Seoul 03080 (Korea, Republic of); Department of Radiology, Seoul National University College of Medicine, Seoul 03087 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 03087 (Korea, Republic of); Yu, Mi Hye [Department of Radiology, Konkuk University Medical Center, Seoul 05030 (Korea, Republic of); Kim, Eun Ju [Philips Healthcare Korea, Seoul 04342 (Korea, Republic of); Han, Joon Koo [Department of Radiology, Seoul National University Hospital, Seoul 03080 (Korea, Republic of); Department of Radiology, Seoul National University College of Medicine, Seoul 03087 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 03087 (Korea, Republic of)

    2016-11-01

    To determine whether triple arterial phase acquisition via a combination of Contrast Enhanced Time Robust Angiography, keyhole, temporal viewsharing and parallel imaging can improve arterial phase acquisition with higher spatial resolution than single arterial phase gadoxetic-acid enhanced magnetic resonance imaging (MRI). Informed consent was waived for this retrospective study by our Institutional Review Board. In 752 consecutive patients who underwent gadoxetic acid-enhanced liver MRI, either single (n = 587) or triple (n = 165) arterial phases was obtained in a single breath-hold under MR fluoroscopy guidance. Arterial phase timing was assessed, and the degree of motion was rated on a four-point scale. The percentage of patients achieving the late arterial phase without significant motion was compared between the two methods using the χ{sup 2} test. The late arterial phase was captured at least once in 96.4% (159/165) of the triple arterial phase group and in 84.2% (494/587) of the single arterial phase group (p < 0.001). Significant motion artifacts (score ≤ 2) were observed in 13.3% (22/165), 1.2% (2/165), 4.8% (8/165) on 1st, 2nd, and 3rd scans of triple arterial phase acquisitions and 6.0% (35/587) of single phase acquisitions. Thus, the late arterial phase without significant motion artifacts was captured in 96.4% (159/165) of the triple arterial phase group and in 79.9% (469/587) of the single arterial phase group (p < 0.001). Triple arterial phase imaging may reliably provide adequate arterial phase imaging for gadoxetic acid-enhanced liver MRI.

  3. Triple arterial phase MR imaging with gadoxetic acid using a combination of contrast enhanced time robust angiography, keyhole, and viewsharing techniques and two-dimensional parallel imaging in comparison with conventional single arterial phase

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jeong Hee; Lee, Jeong Min; Han, Joon Koo [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of); Yu, Mi Hye [Dept. of Radiology, Konkuk University Medical Center, Seoul (Korea, Republic of); Kim, Eun Ju [Philips Healthcare Korea, Seoul (Korea, Republic of)

    2016-07-15

    To determine whether triple arterial phase acquisition via a combination of Contrast Enhanced Time Robust Angiography, keyhole, temporal viewsharing and parallel imaging can improve arterial phase acquisition with higher spatial resolution than single arterial phase gadoxetic-acid enhanced magnetic resonance imaging (MRI). Informed consent was waived for this retrospective study by our Institutional Review Board. In 752 consecutive patients who underwent gadoxetic acid-enhanced liver MRI, either single (n = 587) or triple (n = 165) arterial phases was obtained in a single breath-hold under MR fluoroscopy guidance. Arterial phase timing was assessed, and the degree of motion was rated on a four-point scale. The percentage of patients achieving the late arterial phase without significant motion was compared between the two methods using the χ2 test. The late arterial phase was captured at least once in 96.4% (159/165) of the triple arterial phase group and in 84.2% (494/587) of the single arterial phase group (p < 0.001). Significant motion artifacts (score ≤ 2) were observed in 13.3% (22/165), 1.2% (2/165), 4.8% (8/165) on 1st, 2nd, and 3rd scans of triple arterial phase acquisitions and 6.0% (35/587) of single phase acquisitions. Thus, the late arterial phase without significant motion artifacts was captured in 96.4% (159/165) of the triple arterial phase group and in 79.9% (469/587) of the single arterial phase group (p < 0.001). Triple arterial phase imaging may reliably provide adequate arterial phase imaging for gadoxetic acid-enhanced liver MRI.

  4. Determining metal ion distributions using resonant scattering at very high-energy K-edges: Bi/Pb in Pb{sub 5}Bi{sub 6}Se{sub 14}

    Energy Technology Data Exchange (ETDEWEB)

    Yuegang, Zhang; Lee, P L; Shastri, S D; Deming, Shu [Argonne National Lab., IL (United States). XOR, Advanced Photon Source; Wilkinson, A P [Georgia Inst. of Tech., Atlanta (United States). School of Chemistry and Biochemistry; Duck-Young, Chung; Kanatzidis, M G [Michigan State Univ., East Lansing (United States). Dept. of Chemistry

    2005-06-01

    Powder diffraction data collected at {proportional_to} 86 keV, and just below both the Pb and the Bi K-edges, on an imaging plate detector using synchrotron radiation from the Advanced Photon Source have been used to examine the Pb/Bi distribution over the 11 crystallographically distinct sites in Pb{sub 5}Bi{sub 6}Se{sub 14} [space group P2{sub 1}/m, a=16.0096(2) Aa, b=4.20148(4) Aa, c=21.5689(3) Aa and {beta}=97.537(1){sup 0}]. The scattering factors needed for the analyses were determined both by Kramers- Kronig transformation of absorption spectra and by analyses of diffraction patterns from reference compounds. Even with the relatively low scattering contrast that is available at the K-edges, it was possible to determine the Pb/Bi distribution and probe the presence of cation site vacancies in the material. The current results indicate that resonant scattering measurements at high-energy K-edges are a viable, and perhaps preferable, route to site occupancies when absorption from the sample or sample environment/container is a major barrier to the acquisition of high-quality resonant scattering data at lower-energy edges.

  5. CT coronary angiography vs. invasive coronary angiography in CHD

    Directory of Open Access Journals (Sweden)

    Anja Hagen

    2012-04-01

    Full Text Available Scientific background: Various diagnostic tests including conventional invasive coronary angiography and non-invasive computed tomography (CT coronary angiography are used in the diagnosis of coronary heart disease (CHD. Research questions: The present report aims to evaluate the clinical efficacy, diagnostic accuracy, prognostic value cost-effectiveness as well as the ethical, social and legal implications of CT coronary angiography versus invasive coronary angiography in the diagnosis of CHD. Methods: A systematic literature search was conducted in electronic data bases (MEDLINE, EMBASE etc. in October 2010 and was completed with a manual search. The literature search was restricted to articles published from 2006 in German or English. Two independent reviewers were involved in the selection of the relevant publications. The medical evaluation was based on systematic reviews of diagnostic studies with invasive coronary angiography as the reference standard and on diagnostic studies with intracoronary pressure measurement as the reference standard. Study results were combined in a meta-analysis with 95 % confidence intervals (CI. Additionally, data on radiation doses from current non-systematic reviews were taken into account. A health economic evaluation was performed by modelling from the social perspective with clinical assumptions derived from the meta-analysis and economic assumptions derived from contemporary German sources. Data on special indications (bypass or in-stent-restenosis were not included in the evaluation. Only data obtained using CT scanners with at least 64 slices were considered. Results: No studies were found regarding the clinical efficacy or prognostic value of CT coronary angiography versus conventional invasive coronary angiography in the diagnosis of CHD. Overall, 15 systematic reviews with data from 44 diagnostic studies using invasive coronary angiography as the reference standard (identification of obstructive

  6. Iodine filter imaging system for subtraction angiography using synchrotron radiation

    Science.gov (United States)

    Umetani, K.; Ueda, K.; Takeda, T.; Itai, Y.; Akisada, M.; Nakajima, T.

    1993-11-01

    A new type of real-time imaging system was developed for transvenous coronary angiography. A combination of an iodine filter and a single energy broad-bandwidth X-ray produces two-energy images for the iodine K-edge subtraction technique. X-ray images are sequentially converted to visible images by an X-ray image intensifier. By synchronizing the timing of the movement of the iodine filter into and out of the X-ray beam, two output images of the image intensifier are focused side by side on the photoconductive layer of a camera tube by an oscillating mirror. Both images are read out by electron beam scanning of a 1050-scanning-line video camera within a camera frame time of 66.7 ms. One hundred ninety two pairs of iodine-filtered and non-iodine-filtered images are stored in the frame memory at a rate of 15 pairs/s. In vivo subtracted images of coronary arteries in dogs were obtained in the form of motion pictures.

  7. Intraarterial digital subtraction angiography

    International Nuclear Information System (INIS)

    Davis, P.C.

    1987-01-01

    Digital subtraction angiography (DSA) refers to a radiographic technique of amplifying low levels of contrast from intravascular iodine into an acceptable image of vascular anatomy. Initial enthusiasm suggested that DSA using intravenous injections (IV-DSA) would eliminate most conventional film-screen angiographic studies. It was soon apparent, however, that IV-DSA examinations were often compromised in those patients who most needed a less invasive study. Indeed, only a 70 to 85 percent accuracy rate was achieved with IV-DSA, primarily due to motion artifact, poor cardiac output, overlap of pertinent vessels, and inability to resolve smaller vessels

  8. Nonenhanced MR angiography techniques

    International Nuclear Information System (INIS)

    Lanzman, R.S.; Kroepil, P.; Blondin, D.; Schmitt, P.

    2011-01-01

    Especially in regard to the potential risks for the development of nephrogenic systemic fibrosis (NSF) following the administration of Gadolinium-based contrast material, nonenhanced MR angiography (MRA) methods are becoming ever more important. Besides well-established time-of-flight (TOF) and phase-contrast (PC) MRA, alternative imaging techniques based on balanced steady-state free precession (bSSFP) and turbo-spin-echo (TSE) sequences are increasingly used in combination with or without arterial spin labeling (ASL) strategies. This article provides an overview of the principles and clinical values of different nonenhanced MRA techniques. In addition, recent nonenhanced MRA developments are presented. (orig.)

  9. X-ray absorption spectroscopic studies of the blue copper site: Metal and ligand K-edge studies to probe the origin of the EPR hyperfine splitting in plastocyanin

    International Nuclear Information System (INIS)

    Shadle, S.E.; Penner-Hahn, J.E.; Schugar, H.J.; Hedman, B.; Hodgson, K.O.; Solomon, E.I.

    1993-01-01

    X-ray absorption spectra for the oxidized blue copper protein plastocyanin and several Cu(II) model complexes have been measured at both the Cu K-edge and the ligand K-edges (Cl and S) in order to elucidate the source of the small parallel hyperfine splitting in the EPR spectra of blue copper centers. Assignment and analysis of a feature in the Cu K-edge X-ray absorption spectrum at ∼8,987 eV as the Cu 1s → 4p + ligand-to-metal charge-transfer shakedown transition has allowed for quantitation of 4p mixing into the ground-state wave function as reflected in the 1s →3d (+4p) intensity at ∼8,979 eV. The results show that distorted tetrahedral (D 2d )CuCl 4 2- is characterized by z mixing, while plastocyanin has only Cu 4p xy mixing. Thus, the small parallel hyperfine splitting in the EPR spectra of D 2d CuCl 4 2- and of oxidized plastocyanin cannot be explained by 12% 4p z mixing into the 3d x 2 -y 2 orbital as had been previously postulated. Data collected at the Cl K-edge for CuCl 4 2- show that the intensity of the ligand pre-edge feature at ∼2,820 eV reflects the degree of covalency between the metal half-occupied orbital and the ligands. The data show that D 2d CuCl 4 2- is not unusually covalent. The source of the small parallel splitting in the EPR of D 2d CuCl 4 2- is discussed. Experiments at the S K-edge (∼2,470 eV) show that plastocyanin is characterized by a highly covalent Cu-S(cysteine) bond relative to the cupric-thiolate model complex [Cu(tet b)(o-SC 6 H 4 CO 2 )]·H 2 O. The XAS results demonstrate that the small parallel hyperfine splitting in the EPR spectra of blue copper sites reflects the high degree of covalency of the copper-thiolate bond. 34 refs., 12 figs., 3 tabs

  10. Spin-Polarization-Induced Preedge Transitions in the Sulfur K-Edge XAS Spectra of Open-Shell Transition-Metal Sulfates: Spectroscopic Validation of σ-Bond Electron Transfer.

    Science.gov (United States)

    Frank, Patrick; Szilagyi, Robert K; Gramlich, Volker; Hsu, Hua-Fen; Hedman, Britt; Hodgson, Keith O

    2017-02-06

    Sulfur K-edge X-ray absorption spectroscopy (XAS) spectra of the monodentate sulfate complexes [M II (itao)(SO 4 )(H 2 O) 0,1 ] (M = Co, Ni, Cu) and [Cu(Me 6 tren)(SO 4 )] exhibit well-defined preedge transitions at 2479.4, 2479.9, 2478.4, and 2477.7 eV, respectively, despite having no direct metal-sulfur bond, while the XAS preedge of [Zn(itao)(SO 4 )] is featureless. The sulfur K-edge XAS of [Cu(itao)(SO 4 )] but not of [Cu(Me 6 tren)(SO 4 )] uniquely exhibits a weak transition at 2472.1 eV, an extraordinary 8.7 eV below the first inflection of the rising K-edge. Preedge transitions also appear in the sulfur K-edge XAS of crystalline [M II (SO 4 )(H 2 O)] (M = Fe, Co, Ni, and Cu, but not Zn) and in sulfates of higher-valent early transition metals. Ground-state density functional theory (DFT) and time-dependent DFT (TDDFT) calculations show that charge transfer from coordinated sulfate to paramagnetic late transition metals produces spin polarization that differentially mixes the spin-up (α) and spin-down (β) spin orbitals of the sulfate ligand, inducing negative spin density at the sulfate sulfur. Ground-state DFT calculations show that sulfur 3p character then mixes into metal 4s and 4p valence orbitals and various combinations of ligand antibonding orbitals, producing measurable sulfur XAS transitions. TDDFT calculations confirm the presence of XAS preedge features 0.5-2 eV below the rising sulfur K-edge energy. The 2472.1 eV feature arises when orbitals at lower energy than the frontier occupied orbitals with S 3p character mix with the copper(II) electron hole. Transmission of spin polarization and thus of radical character through several bonds between the sulfur and electron hole provides a new mechanism for the counterintuitive appearance of preedge transitions in the XAS spectra of transition-metal oxoanion ligands in the absence of any direct metal-absorber bond. The 2472.1 eV transition is evidence for further radicalization from copper(II), which

  11. Magnetic resonance angiography (MRA) of the calf station at 3.0 T: intraindividual comparison of non-enhanced ECG-gated flow-dependent MRA, continuous table movement MRA and time-resolved MRA

    International Nuclear Information System (INIS)

    Haneder, Stefan; Attenberger, Ulrike I.; Riffel, Philipp; Henzler, Thomas; Schoenberg, Stefan O.; Michaely, Henrik J.

    2011-01-01

    To compare 3D non-enhanced ECG-gated inflow-dependent MRA (NE-MRA) vs. continuous table movement (CTM) MR-angiography and time-resolved TWIST-MRA in the calf station at 3.0 T in a clinical patient collective. 36 patients (27 male/9 female, 66.1 ± 14.4 years) with PAOD (stage II-IV) underwent during a single MRI: NE-MRA, contrast-enhanced CTM-MRA and TWIST-MRA with a single dose of a gadolinium-based contrast agent. The image quality (IQ) and the degree of stenoses were rated on a four-point scale. Positive (PPV) and negative predictive values (NPV), sensitivity (SS) and specificity (SP) for stenoses detection were calculated for NE-MRA vs. CTM-MRA and vs. TWIST-MRA. Values were obtained for overall graduation of wall changes and for severe stenoses (>70%). With NE-MRA 122/288 segments were not assessable. Compared with CTM-MRA and TWIST-MRA the IQ was significantly inferior (p < 0.0001 to p = 0.0426). CTM-MRA/TWIST-MRA detected stenoses in 44.9%/46.1% of the segments, NE-MRA in 53.5%. SS/NPV of the NE-MRA ranged from 97.8 to 100%. The SP and PPV ranged from 72.7 to 85.5% and 66.7 to 78.2%. Contrast-enhanced MRA techniques are superior to NE-MRA regarding IQ and correct identification of stenoses. If technically successful, NE-MRA is characterised by high NPV and overestimation of the degree of stenoses. (orig.)

  12. Left Gastric Vein Visualization with Hepatopetal Flow Information in Healthy Subjects Using Non-Contrast-Enhanced Magnetic Resonance Angiography with Balanced Steady-State Free-Precession Sequence and Time-Spatial Labeling Inversion Pulse.

    Science.gov (United States)

    Furuta, Akihiro; Isoda, Hiroyoshi; Ohno, Tsuyoshi; Ono, Ayako; Yamashita, Rikiya; Arizono, Shigeki; Kido, Aki; Sakashita, Naotaka; Togashi, Kaori

    2018-01-01

    To selectively visualize the left gastric vein (LGV) with hepatopetal flow information by non-contrast-enhanced magnetic resonance angiography under a hypothesis that change in the LGV flow direction can predict the development of esophageal varices; and to optimize the acquisition protocol in healthy subjects. Respiratory-gated three-dimensional balanced steady-state free-precession scans were conducted on 31 healthy subjects using two methods (A and B) for visualizing the LGV with hepatopetal flow. In method A, two time-spatial labeling inversion pulses (Time-SLIP) were placed on the whole abdomen and the area from the gastric fornix to the upper body, excluding the LGV area. In method B, nonselective inversion recovery pulse was used and one Time-SLIP was placed on the esophagogastric junction. The detectability and consistency of LGV were evaluated using the two methods and ultrasonography (US). Left gastric veins by method A, B, and US were detected in 30 (97%), 24 (77%), and 23 (74%) subjects, respectively. LGV flow by US was hepatopetal in 22 subjects and stagnant in one subject. All hepatopetal LGVs by US coincided with the visualized vessels in both methods. One subject with non-visualized LGV in method A showed stagnant LGV by US. Hepatopetal LGV could be selectively visualized by method A in healthy subjects.

  13. Iron deposition of the deep grey matter in patients with multiple sclerosis and neuromyelitis optica: A control quantitative study by 3D-enhanced susceptibility-weighted angiography (ESWAN)

    International Nuclear Information System (INIS)

    Chen Xuan; Zeng Chun; Luo Tianyou; Ouyang Yu; Lv Fajin; Rumzan, Reshiana; Wang Zhongping; Li Qi; Wang Jingjie; Hou Huanxin

    2012-01-01

    Purpose: Previous studies have detected abnormal iron deposition in the deep grey matter (DGM) of multiple sclerosis (MS). The regional specificity of the DGM iron deposition in neuromyelitis optica (NMO) is still unclear. We compared the differences in the DGM iron concentration between MS and NMO patients. Methods: We enrolled 42 relapsing–remitting MS (RRMS) patients, 42 NMO patients and 42 healthy controls undergoing brain conventional MRI and three-dimensional (3D)-enhanced T 2 *-weighted angiography (ESWAN) sequences. We obtained the mean phase values (MPVs) for ESWAN-filtered phase images. An analysis of covariance (ANCOVA) was used to compare MPVs among three groups. The correlations of MPVs changes with disease duration and expanded disability status scale (EDSS) were analyzed. Results: The RRMS patients had higher DGM iron concentration than did the NMO and control groups, but only the bilateral substantia nigra (SN) showed a significant statistical difference among three groups (p 0.05). Furthermore, no correlations were found between the DGM iron concentration and EDSS (p > 0.05). Conclusions: We confirm the iron concentration in the DGM iron content of MS patients is more than NMO patients and healthy controls in the same age range. Furthermore, the disease duration was found to be a significant contributor to patients with MS.

  14. Noncontrast MR angiography (MRA) of infragenual arteries using flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) at 3.0 Tesla: Comparison with contrast-enhanced MRA.

    Science.gov (United States)

    Zhang, Nan; Fan, Zhaoyang; Luo, Nan; Bi, Xiaoming; Zhao, Yike; An, Jing; Liu, Jiayi; Chen, Zhong; Fan, Zhanming; Li, Debiao

    2016-02-01

    To evaluate the feasibility and diagnostic performance of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) MR angiography (MRA) for imaging infragenual arteries at 3.0T, with contrast enhanced MR angiography (CE MRA) as reference. Twenty consecutive patients with suspicion of lower extremity arterial disease undergoing routine CE MRA were recruited. FSD MRA was performed at calf before CE MRA. Image quality and stenosis degree of infragenual arteries from both techniques were independently evaluated and compared. Six patients in this study underwent DSA examination. Three undiagnostic segments were excluded with severe venous contamination in CE MRA. A total of 197 calf arterial segments images were analyzed. No significant difference existed in the relative signal intensity (rSI) of arterial segments between FSD MRA and CE MRA techniques (0.92 ± 0.09 versus 0.93 ± 0.05; P = 0.207). However, the subjective image quality score was slightly higher in FSD MRA (3.66 ± 0.81 versus 3.49 ± 0.87; P = 0.050). With CE MRA images as reference standard, slight overestimation existed in FSD MRA (2.19 ± 1.24 versus 2.09 ± 1.18; P = 0.019), with total agreement of 84.3% on the basis of all arterial segments. The sensitivity, specificity, negative predictive value, and positive predictive value of FSD MRA was 96.4%, 93.0%, 98.5%, and 84.1%. No significant difference in the stenosis degree score was detected between MRA (FSD MRA and CE MRA) and DSA (P > 0.05). FSD MRA performed on at 3.0T without the use of contrast medium provides diagnostic images allowing for arterial stenosis assessment of calf arteries that was highly comparable with CE MRA. Moreover, venous contamination was less problematic with FSD MRA. © 2015 Wiley Periodicals, Inc.

  15. Superselective pseudo-continuous arterial spin labeling angiography

    Energy Technology Data Exchange (ETDEWEB)

    Jensen-Kondering, Ulf [Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel (Germany); Lindner, Thomas, E-mail: thomas.lindner@uksh.de [Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel (Germany); Osch, Matthias J.P. van [C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden (Netherlands); Rohr, Axel; Jansen, Olav [Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel (Germany); Helle, Michael [Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel (Germany); Now with Philips GmbH Innovative Technologies, Research Laboratories, Hamburg (Germany)

    2015-09-15

    Highlights: • Superselective arterial spin labeling was capable of acquiring angiograms of individually selected arteries. • Image quality was similar compared with a routinely used time-of-flight angiography. • Superselective arterial spin labeling was utilized in patients with arterio-venous malformations and made it possible to visualize individual feeding vessels in a complete non-invasive way - Abstract: Purpose: To evaluate the utility of a novel non-contrast enhanced, vessel-selective magnetic resonance angiography (MRA) approach based on superselective pseudo-continuous arterial spin labeling (ASL) for the morphologic assessment of intracranial arteries when compared to a clinically used time-of-flight (TOF) MRA. Materials and methods: Three sets of selective ASL angiographies (right and left internal carotid artery, basilar artery) as well as one TOF data set were obtained from each of the five volunteers included in this study on a clinical 1.5T system. The depiction of arterial segments as well as their delineation was evaluated and independently analyzed by two radiologists. Additionally, the ASL angiography approach was performed in two patients suffering from arterio-venous malformations (AVM) in order to illustrate potential applications in a clinical setting. Results: In both angiography techniques, intracranial arteries and their segments (distal branches up to A5 segments of the anterior cerebral arteries, M8 segments of the middle cerebral arteries, and P5 segments of the posterior cerebral arteries) were continuously depicted with excellent inter-reader agreement (κ > 0.81). In AVM patients, reconstructed images of the TOF angiography presented similar information about the size and shape of the AVM as did superselective ASL angiography. In addition, the acquired ASL angiograms of selected vessels allowed assessing the blood supply of individually labeled arteries to the AVM which could also be confirmed by digital subtraction angiography

  16. Superselective pseudo-continuous arterial spin labeling angiography

    International Nuclear Information System (INIS)

    Jensen-Kondering, Ulf; Lindner, Thomas; Osch, Matthias J.P. van; Rohr, Axel; Jansen, Olav; Helle, Michael

    2015-01-01

    Highlights: • Superselective arterial spin labeling was capable of acquiring angiograms of individually selected arteries. • Image quality was similar compared with a routinely used time-of-flight angiography. • Superselective arterial spin labeling was utilized in patients with arterio-venous malformations and made it possible to visualize individual feeding vessels in a complete non-invasive way - Abstract: Purpose: To evaluate the utility of a novel non-contrast enhanced, vessel-selective magnetic resonance angiography (MRA) approach based on superselective pseudo-continuous arterial spin labeling (ASL) for the morphologic assessment of intracranial arteries when compared to a clinically used time-of-flight (TOF) MRA. Materials and methods: Three sets of selective ASL angiographies (right and left internal carotid artery, basilar artery) as well as one TOF data set were obtained from each of the five volunteers included in this study on a clinical 1.5T system. The depiction of arterial segments as well as their delineation was evaluated and independently analyzed by two radiologists. Additionally, the ASL angiography approach was performed in two patients suffering from arterio-venous malformations (AVM) in order to illustrate potential applications in a clinical setting. Results: In both angiography techniques, intracranial arteries and their segments (distal branches up to A5 segments of the anterior cerebral arteries, M8 segments of the middle cerebral arteries, and P5 segments of the posterior cerebral arteries) were continuously depicted with excellent inter-reader agreement (κ > 0.81). In AVM patients, reconstructed images of the TOF angiography presented similar information about the size and shape of the AVM as did superselective ASL angiography. In addition, the acquired ASL angiograms of selected vessels allowed assessing the blood supply of individually labeled arteries to the AVM which could also be confirmed by digital subtraction angiography

  17. Optical Coherence Tomography Angiography in Retinal Diseases.

    Science.gov (United States)

    Chalam, K V; Sambhav, Kumar

    2016-01-01

    Optical coherence tomography angiography (OCTA) is a new, non-invasive imaging system that generates volumetric data of retinal and choroidal layers. It has the ability to show both structural and blood flow information. Split-spectrum amplitude-decorrelation angiography (SSADA) algorithm (a vital component of OCTA software) helps to decrease the signal to noise ratio of flow detection thus enhancing visualization of retinal vasculature using motion contrast. Published studies describe potential efficacy for OCTA in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age related macular degeneration (AMD), retinal vascular occlusions and sickle cell disease. OCTA provides a detailed view of the retinal vasculature, which allows accurate delineation of microvascular abnormalities in diabetic eyes and vascular occlusions. It helps quantify vascular compromise depending upon the severity of diabetic retinopathy. OCTA can also elucidate the presence of choroidal neovascularization (CNV) in wet AMD. In this paper, we review the knowledge, available in English language publications regarding OCTA, and compare it with the conventional angiographic standard, fluorescein angiography (FA). Finally, we summarize its potential applications to retinal vascular diseases. Its current limitations include a relatively small field of view, inability to show leakage, and tendency for image artifacts. Further larger studies will define OCTA's utility in clinical settings and establish if the technology may offer a non-invasive option of visualizing the retinal vasculature, enabling us to decrease morbidity through early detection and intervention in retinal diseases.

  18. Analogous Three-Dimensional Constructive Interference in Steady State Sequences Enhance the Utility of Three-Dimensional Time of Flight Magnetic Resonance Angiography in Delineating Lenticulostriate Arteries in Insular Gliomas: Evidence from a Prospective Clinicoradiologic Analysis of 48 Patients.

    Science.gov (United States)

    Rao, Arun S; Thakar, Sumit; Sai Kiran, Narayanam Anantha; Aryan, Saritha; Mohan, Dilip; Hegde, Alangar S

    2018-01-01

    Three-dimensional (3D) time of flight (TOF) imaging is the current gold standard for noninvasive, preoperative localization of lenticulostriate arteries (LSAs) in insular gliomas; however, the utility of this modality depends on tumor intensity. Over a 3-year period, 48 consecutive patients with insular gliomas were prospectively evaluated. Location of LSAs and their relationship with the tumor were determined using a combination of contrast-enhanced coronal 3D TOF magnetic resonance angiography and coronal 3D constructive interference in steady state (CISS) sequences. These findings were analyzed with respect to extent of tumor resection and early postoperative motor outcome. Tumor was clearly visualized in 29 (60.4%) patients with T1-hypointense tumors using 3D TOF and in all patients using CISS sequences. Using combined 3D TOF and CISS, LSA-tumor interface was well seen in 47 patients, including all patients with T1-heterointense or T1-isointense tumors. Extent of resection was higher in the LSA-pushed group compared with the LSA-encased group. In the LSA-encased group, 6 (12.5%) patients developed postoperative hemiparesis; 2 (4.2%) cases were attributed to LSA injury. Contrast-enhanced 3D TOF can delineate LSAs in almost all insular gliomas but is limited in identifying the LSA-tumor interface. This limitation can be overcome by addition of analogous CISS sequences that delineate the LSA-tumor interface regardless of tumor intensity. Combined 3D TOF and 3D CISS is a useful tool for surgical planning and safer resections of insular tumors and may have added surgical relevance when included as an intraoperative adjunct. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Contrast-enhanced magnetic resonance angiography (MRA): evaluation of three different contrast agents at two different doses (0.05 and 0.1 mmol/kg) in pigs at 1.5 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Voth, M.; Vos, B.; Pietsch, H. [Bayer Schering Pharma AG, Diagnostic Imaging, Berlin (Germany); Michaely, Henrik J. [University of Heidelberg, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Mannheim (Germany); Schwenke, C. [ScoSSiS - Statistical Consulting, Berlin (Germany)

    2011-02-15

    To compare the image quality of contrast-enhanced magnetic resonance angiography (CE-MRA) of the supra-aortic vessels at 0.05 mmol/kg bw and 0.1 mmol/kg bw, between gadobutrol, Gd-DTPA and Gd-BOPTA quantitatively and qualitatively a total of eight pigs were evaluated intraindividually at 1.5 T. Each pig was examined using 0.1 mmol/kg gadobutrol, Gd-DTPA and Gd-BOPTA on day one and 0.05 mmol/kg on day two. MRA datasets for the carotid artery and the infraorbital artery were qualitatively assessed regarding overall image quality on an ordinal four-point scale (4-excellent, 1-non-diagnostic). The signal-to noise-ratio (SNR) was measured. The qualitative assessment of the carotid artery showed a higher median image quality for the 0.1 mmol dose than for the 0.05 mmol dose for all three compounds. No difference was found for the infraorbital artery. Mean SNR of Gd-BOPTA, Gd-DTPA, gadobutrol at 0.05 mmol/kg were 36.0 {+-} 13.4/37.9 {+-} 16.3/43.7 {+-} 0.4 and at 0.1 mmol/kg they were 50.1 {+-} 12.4/46.6 {+-} 6.5 / 54.6 {+-} 10.2. Gd-BOPTA 0.05 revealed a significantly lower SNR than all other agents at normal dose. Full-dose gadolinium MRA results in higher image quality and significantly higher SNR compared with the half dose. Gadobutrol and Gd-BOPTA have similar enhancement properties at full dose but at half dose, gadobutrol appears superior. (orig.)

  20. Preoperative examination of potential renal transplant donors: value of gadolinium-enhanced 3D-MR-angiography in comparison with DSA and urography

    International Nuclear Information System (INIS)

    Winterer, J.T.; Paul, G.; Einert, A.; Altehoefer, C.; Uhrmeister, P.; Laubenberger, J.

    2000-01-01

    Purpose: To assess a contrast-enhanced standardized MRA protocol for the presurgical evaluation of potential renal transplant donors. Methods: Twenty-three potential donors for renal transplantations were examined with gadolinium-enhanced, two-phase MR angiograms (1.5 T) and DSA/urography for the number of renal arteries, the presence of aberrant arterial and venous branches, renal artery stenoses and anatomy of the renal collecting system and ureters. The diagnostic value was assessed by evaluating different image processing modalities and interobserver variability. Results: Using maximum intensity projections (MIP) together with multiplanar reformatting (MPR), accessory arteries were detected with a sensitivity/specificity of 100%/98%. Depending on diagnostic experience, exclusive evaluation of MIP yielded a sensitivitiy/specificity of 67-100%/95-100%. Using MIP/MPR, venous depiction was good in 80%, with MIP solely in 30-40%. At least the proximal third of the ureter was visible in 67%. Conclusion: MPR/MIP evaluation of two-phase, contrast-enhanced MRA provides an excellent depiction of renal vessel anatomy for presurgical evaluation of renal transplant donors. Exclusive MIP assessment is less reliable and depends strongly on the examiner's experience. For sufficient visualization of the ureters, either additional measurements or low-dose diuretic injection have to be performed. (orig.) [de

  1. Angiography and interventional radiology of the kidneys

    International Nuclear Information System (INIS)

    Hansmann, J.; Richter, G.M.; Hallscheidt, P.; Duex, M.; Noeldge, G.; Kaufmann, G.W.

    1999-01-01

    For imaging of renal pathology a broad spectrum of radiologic diagnostic procedures are available which are, sometimes and particularly more recently, competing among each other in their diagnostic yield and relevance. For tumorous lesions ultrasound, computed tomography and magnetic resonance imaging are performed predominantly. Angiography is no longer required with the exception of highly selected cases and in some specific preoperative workup requirements. Until recently, catheter based digital subtraction angiography has been considered as gold standard. However, non-invasive techniques such as CT-angiography and MR-angiography are evolving parallel to their quantum leap of resolutions and readiness to use. Nevertheless, well accepted criteria for quality assessement of these new modalities are still lacking. More comparison studies are urgently warranted. Despite the availability of ultrashort pulse sequences applying the T1 relaxation reduction effect of gadolinium enhanced MR techniques overestimation of renal artery stenosis still poses a substantial problem. Renal intervention implies a variety of procedures such as plain angioplasty, stent placement, embolization of traumatic and both benign and malignant tumors. These methods have emerged over the last two decades from a more experimental nature to a fully accepted treatment option. When renal artery angioplasty is embedded in an aggressive approach including stenting as an adjunct for more complex cases, renal ostial lesions and a well organized follow-up regimen its therapeutic potential for treatment of renal insufficiency, malignant hypertension, for organ preservation bears a very high potential. Provided adequate periinterventional drug regimen restenosis rates may be as low as 10%. In highly selected cases capillary embolization might be used as an alternative to nephrectomy with a similar clinical outcome. Particularly the development of superselective small caliber embolization catheters

  2. Magnetic resonance angiography

    International Nuclear Information System (INIS)

    Kauczor, H.U.; Gamroth, A.H.; Schad, L.R.; Semmler, W.; Kaick, G. van; Tuengerthal, S.J.; Hausmann, R.

    1992-01-01

    MR angiography (MRA) proved to be promising combined to MR-Imaging (MRI) in the assessment of intrathoracic masses. Sequential FLASH 2D-angiograms were acquired in breathhold technique using the following parameters: TR=30 ms, TE=10 ms, FA=30deg. Section thickness was 5 mm with 1 mm overlap between sequential sections. Individual conditions of the examination were achieved by an automatised control procedure. Targeted MIP-postprocessing resulted in 3D-reconstructions illustrating vascular anatomy and avoiding superimposition. Presentation should be done by cine-mode for better spatial impression. This method was evaluated in a prospective study of 21 patients with malignant pulmonary and mediastinal masses in addition to spin-echo imaging. The diagnostic contribution concerning the relationship between the mass and the vasculature like displacement, stenosis, and poststenotic perfusion defect were assessed. (orig.) [de

  3. Digital subtraction angiography

    International Nuclear Information System (INIS)

    Neuwirth, J. Jr.; Bohutova, J.

    1987-01-01

    The quality of radiodiagnostic methods to a great extent depends on the quality of the resulting image. The basic technical principles are summed up of the different parts of digital subtraction angiography apparatus and of methods of improving the image. The instrument is based on a videochain consisting of an X-ray tube, an intensifier of the radiographic image, optical parts, a video camera, an analog-to-digital converter and a computer. The main advantage of the digitally processed image is the possibility of optimizing the image into a form which will contain the biggest amount of diagnostically valuable information. Described are the mathematical operations for improving the digital image: spatial filtration, pixel shift, time filtration, image integration, time interval differentation and matched filtering. (M.D.). 8 refs., 3 figs

  4. Angiography and interventional radiology of the kidneys; Angiographie und interventionelle Radiologie der Nieren

    Energy Technology Data Exchange (ETDEWEB)

    Hansmann, J.; Richter, G.M.; Hallscheidt, P.; Duex, M.; Noeldge, G.; Kaufmann, G.W. [Heidelberg Univ. (Germany). Abt. Radiodiagnostik

    1999-05-01

    For imaging of renal pathology a broad spectrum of radiologic diagnostic procedures are available which are, sometimes and particularly more recently, competing among each other in their diagnostic yield and relevance. For tumorous lesions ultrasound, computed tomography and magnetic resonance imaging are performed predominantly. Angiography is no longer required with the exception of highly selected cases and in some specific preoperative workup requirements. Until recently, catheter based digital subtraction angiography has been considered as gold standard. However, non-invasive techniques such as CT-angiography and MR-angiography are evolving parallel to their quantum leap of resolutions and readiness to use. Nevertheless, well accepted criteria for quality assessement of these new modalities are still lacking. More comparison studies are urgently warranted. Despite the availability of ultrashort pulse sequences applying the T1 relaxation reduction effect of gadolinium enhanced MR techniques overestimation of renal artery stenosis still poses a substantial problem. Renal intervention implies a variety of procedures such as plain angioplasty, stent placement, embolization of traumatic and both benign and malignant tumors. These methods have emerged over the last two decades from a more experimental nature to a fully accepted treatment option. When renal artery angioplasty is embedded in an aggressive approach including stenting as an adjunct for more complex cases, renal ostial lesions and a well organized follow-up regimen its therapeutic potential for treatment of renal insufficiency, malignant hypertension, for organ preservation bears a very high potential. Provided adequate periinterventional drug regimen restenosis rates may be as low as 10%. In highly selected cases capillary embolization might be used as an alternative to nephrectomy with a similar clinical outcome. Particularly the development of superselective small caliber embolization catheters

  5. Resonant inelastic x-ray scattering on iso-C{sub 2}H{sub 2}Cl{sub 2} around the chlorine K-edge: Structural and dynamical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Kawerk, Elie, E-mail: eliekawerk@hotmail.com, E-mail: ekawerk@units.it [CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris (France); Sorbonne Universités, UPMC Université Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris (France); Laboratoire de Physique Appliquée, Faculté des Sciences II, Université Libanaise, 90656 Jdeidet el Metn, Liban (Libya); Dipartimento di Scienze Chimiche, Università di Trieste, Via L. Giorgieri 1, I-34127 Trieste (Italy); Carniato, Stéphane; Journel, Loïc; Marchenko, Tatiana; Simon, Marc [CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris (France); Sorbonne Universités, UPMC Université Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris (France); Piancastelli, Maria Novella [CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris (France); Sorbonne Universités, UPMC Université Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris (France); Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); Žitnik, Matjaž; Bučar, Klemen; Bohnic, Rok [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); and others

    2014-10-14

    We report a theoretical and experimental study of the high resolution resonant K{sub α} X-ray emission lines around the chlorine K-edge in gas phase 1,1-dichloroethylene. With the help of ab initio electronic structure calculations and cross section evaluation, we interpret the lowest lying peak in the X-ray absorption and emission spectra. The behavior of the K{sub α} emission lines with respect to frequency detuning highlights the existence of femtosecond nuclear dynamics on the dissociative Potential Energy Surface of the first K-shell core-excited state.

  6. Digital angiography in pulmonary embolism

    International Nuclear Information System (INIS)

    Bjoerk, L.

    1986-01-01

    Pulmonary digital subtraction angiography was diagnostic in 98.3% of patients with possible acute pulmonary embolism. The procedure was well tolerated even in severely ill patients. A large image intensifier made simultaneous imaging of both lungs possible reducing the number of contrast injections necessary. Small volumes of low iso-osmolar concentration of modern contrast media were used. There was no need for catherization of the pulmonary artery. Theoretical considerations and our limited experience indicate that this will reduce the number of complications compared with conventional pulmonary angiography. The procedure is rapidly performed and the diagnostic accuracy high. This makes digital subtraction angiography cost effective. Digital pulmonary angiography can be recommended as the primary diagnostic method in most patients with possible pulmonary embolism. (orig.)

  7. 3D Deep Learning Angiography (3D-DLA) from C-arm Conebeam CT.

    Science.gov (United States)

    Montoya, J C; Li, Y; Strother, C; Chen, G-H

    2018-05-01

    Deep learning is a branch of artificial intelligence that has demonstrated unprecedented performance in many medical imaging applications. Our purpose was to develop a deep learning angiography method to generate 3D cerebral angiograms from a single contrast-enhanced C-arm conebeam CT acquisition in order to reduce image artifacts and radiation dose. A set of 105 3D rotational angiography examinations were randomly selected from an internal data base. All were acquired using a clinical system in conjunction with a standard injection protocol. More than 150 million labeled voxels from 35 subjects were used for training. A deep convolutional neural network was trained to classify each image voxel into 3 tissue types (vasculature, bone, and soft tissue). The trained deep learning angiography model was then applied for tissue classification into a validation cohort of 8 subjects and a final testing cohort of the remaining 62 subjects. The final vasculature tissue class was used to generate the 3D deep learning angiography images. To quantify the generalization error of the trained model, we calculated the accuracy, sensitivity, precision, and Dice similarity coefficients for vasculature classification in relevant anatomy. The 3D deep learning angiography and clinical 3D rotational angiography images were subjected to a qualitative assessment for the presence of intersweep motion artifacts. Vasculature classification accuracy and 95% CI in the testing dataset were 98.7% (98.3%-99.1%). No residual signal from osseous structures was observed for any 3D deep learning angiography testing cases except for small regions in the otic capsule and nasal cavity compared with 37% (23/62) of the 3D rotational angiographies. Deep learning angiography accurately recreated the vascular anatomy of the 3D rotational angiography reconstructions without a mask. Deep learning angiography reduced misregistration artifacts induced by intersweep motion, and it reduced radiation exposure

  8. New method of digital angiography

    International Nuclear Information System (INIS)

    Hashiya, Junichi; Korenaga, Takeo; Sakurai, Kenji; Sakai, Fumikazu; Kato, Hisatoyo; Takano, Masao.

    1982-01-01

    New experience of digital angiography using Fuji Intelligent Diagnostic X-ray System was reported. The system utilizes newly developed high sensitivity imaging plate in conjunction with computerized image processor instead of image intensifier-TV series, thus drastically improving image quality. Initial clinical trial was made in 46 cases including intravenous digital subtraction angiography and transcatheter digital arteriography. The advantages of this method were summerized as: 1. better resolution, 2. wider field size, 3. more sophisticated image manipulation program. (author)

  9. Three-dimensional contrast-enhanced magnetic resonance angiography (3-D CE-MRA) in the evaluation of hemodialysis access complications, and the condition of central veins in patients who are candidates for hemodialysis access.

    Science.gov (United States)

    Paksoy, Yahya; Gormus, Niyazi; Tercan, Mehmet Akif

    2004-01-01

    Arteriovenous (AV) fistulas are crucial in patients requiring long-term hemodialysis (HD). Dysfunctions of these fistulas are the most common causes of recurrent hospitalizations. This study aimed to evaluate the feasibility, safety and usefulness of contrast-enhanced magnetic resonance angiography (CE-MRA) in the evaluation of HD fistulas complications, and the condition of the central veins before HD access. This study comprised 30 consecutive patients (15 females, 15 males; age range 25-66 yrs, mean +/- SD 51.2 +/- 9.9 yrs). Of 30 patients, 26 had native AV fistulas and the remaining four patients, who had a history of previous subclavian vein catheterization, were candidates for HD fistulas. Nine patients had a radiocephalic fistula, 15 had a brachiobasilic fistula, one had a saphenous vein graft, and one had brachiobasilic vein transposition. To observe the fistula complications in these cases, three-dimensional (3-D) CE-MRA using gadolinium was performed. The results were considered normal in three patients (10%), who were candidates for AV fistula construction; one patient had central vein occlusion due to previous catheterization. Thirteen patients (43.3%) had venous stenosis or occlusion; three of them (10%) had low CE arteries distal to fistula region, leading to ischemic complications, and six (20%) had stenosis at the fistula region. Seven patients (23.3%) had venous pseudoaneurysms, whereas two of them had both pseudoaneurysms and fistula region stenosis, and one had both venous stenosis and pseudoaneurysm. There were no adverse or allergic-like reactions or heat and taste sensations observed in our series. 3-D CE-MRA is a useful, safe and a practical imaging modality in complicated fistula diagnosis with fewer complications and side-effects in comparison to fistulography.

  10. Non-contrast-enhanced hepatic MR angiography: Do two-dimensional parallel imaging and short tau inversion recovery methods shorten acquisition time without image quality deterioration?

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Kotaro, E-mail: kotaro@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Isoda, Hiroyoshi, E-mail: sayuki@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Okada, Tomohisa, E-mail: tomokada@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Kamae, Toshikazu, E-mail: toshi13@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Arizono, Shigeki, E-mail: arizono@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Hirokawa, Yuusuke, E-mail: yuusuke@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Shibata, Toshiya, E-mail: ksj@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Togashi, Kaori, E-mail: ktogashi@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan)

    2011-01-15

    Objective: To study whether shortening the acquisition time for selective hepatic artery visualization is feasible without image quality deterioration by adopting two-dimensional (2D) parallel imaging (PI) and short tau inversion recovery (STIR) methods. Materials and methods: Twenty-four healthy volunteers were enrolled. 3D true steady-state free-precession imaging with a time spatial labeling inversion pulse was conducted using 1D or 2D-PI and fat suppression by chemical shift selective (CHESS) or STIR methods. Three groups of different scan conditions were assigned and compared: group A (1D-PI factor 2 and CHESS), group B (2D-PI factor 2 x 2 and CHESS), and group C (2D-PI factor 2 x 2 and STIR). The artery-to-liver contrast was quantified, and the quality of artery visualization and overall image quality were scored. Results: The mean scan time was 9.5 {+-} 1.0 min (mean {+-} standard deviation), 5.9 {+-} 0.8 min, and 5.8 {+-} 0.5 min in groups A, B, and C, respectively, and was significantly shorter in groups B and C than in group A (P < 0.01). The artery-to-liver contrast was significantly better in group C than in groups A and B (P < 0.01). The scores for artery visualization and overall image quality were worse in group B than in groups A and C. The differences were statistically significant (P < 0.05) regarding the arterial branches of segments 4 and 8. Between group A and group C, which had similar scores, there were no statistically significant differences. Conclusion: Shortening the acquisition time for selective hepatic artery visualization was feasible without deterioration of the image quality by the combination of 2D-PI and STIR methods. It will facilitate using non-contrast-enhanced MRA in clinical practice.

  11. Non-contrast-enhanced hepatic MR angiography: Do two-dimensional parallel imaging and short tau inversion recovery methods shorten acquisition time without image quality deterioration?

    International Nuclear Information System (INIS)

    Shimada, Kotaro; Isoda, Hiroyoshi; Okada, Tomohisa; Kamae, Toshikazu; Arizono, Shigeki; Hirokawa, Yuusuke; Shibata, Toshiya; Togashi, Kaori

    2011-01-01

    Objective: To study whether shortening the acquisition time for selective hepatic artery visualization is feasible without image quality deterioration by adopting two-dimensional (2D) parallel imaging (PI) and short tau inversion recovery (STIR) methods. Materials and methods: Twenty-four healthy volunteers were enrolled. 3D true steady-state free-precession imaging with a time spatial labeling inversion pulse was conducted using 1D or 2D-PI and fat suppression by chemical shift selective (CHESS) or STIR methods. Three groups of different scan conditions were assigned and compared: group A (1D-PI factor 2 and CHESS), group B (2D-PI factor 2 x 2 and CHESS), and group C (2D-PI factor 2 x 2 and STIR). The artery-to-liver contrast was quantified, and the quality of artery visualization and overall image quality were scored. Results: The mean scan time was 9.5 ± 1.0 min (mean ± standard deviation), 5.9 ± 0.8 min, and 5.8 ± 0.5 min in groups A, B, and C, respectively, and was significantly shorter in groups B and C than in group A (P < 0.01). The artery-to-liver contrast was significantly better in group C than in groups A and B (P < 0.01). The scores for artery visualization and overall image quality were worse in group B than in groups A and C. The differences were statistically significant (P < 0.05) regarding the arterial branches of segments 4 and 8. Between group A and group C, which had similar scores, there were no statistically significant differences. Conclusion: Shortening the acquisition time for selective hepatic artery visualization was feasible without deterioration of the image quality by the combination of 2D-PI and STIR methods. It will facilitate using non-contrast-enhanced MRA in clinical practice.

  12. In-plant measurements of gamma-ray transmissions for precise K-edge and passive assay of plutonium concentration and isotopic abundance in product solutions at the Tokai Reprocessing Plant

    International Nuclear Information System (INIS)

    Asakura, Y.; Kondo, I.; Masui, J.; Shoji, K.; Russo, P.A.; Hsue, S.T.; Sprinkle, J.K. Jr.; Johnson, S.S.

    1982-01-01

    A field test has been carried out for more than 2 years for determination of plutonium concentration by K-edge absorption densitometry and for determination of plutonium isotopic abundance by transmission-corrected passive gamma-ray spectrometry. This system was designed and built at Los Alamos National Laboratory and installed at the Tokai reprocessing plant of the Power Reactor and Nuclear Fuel Development Corporation as a part of the Tokai Advanced Safeguards Technology Exercise (TASTEX). For K-edge measurement of plutonium concentration, the transmissions at two discrete gamma-ray energies are measured using the 121.1- and 122.1-keV gamma rays from 75 Se and 57 Co. Intensities of the plutonium passive gamma rays in the energy regions between 38 and 51 keV and between 129 and 153 keV are used for determination of the isotopic abundances. More than 200 product solution samples have been measured in a timely fashion during these 2 years. The relative precisions and accuracies of the plutonium concentration measurement are shown to be within 0.6% (1 sigma) in these applications, and those for plutonium isotopic abundances are within 3% for 238 Pu, 0.4% for 239 Pu, 1.2% for 240 Pu, 1.3% for 241 Pu, and 7% for 242 Pu. The time required is 10 min for the concentration assay, 10 min for the isotopics assay, and about 15 min for handling procedures in the laboratory

  13. The clinical value of 3D dynamic contrast enhanced MR angiography on haemorrhage of esophageal and gastric varices compared with endoscopy

    International Nuclear Information System (INIS)

    Wu Zhou; Liang Biling; Li Yong; Zhong Jinglian; Ye Ruixin; Wang Dongye; Li Chuqiang; Yuan Yuhong

    2010-01-01

    Objective: To investigate the clinical value of three dimensional dynamic contrast enhanced MRA (3D DCE MRA) on esophageal and gastric varices compared with endoscopy. Methods: From April 2003 to June 2008, 153 patients with portal hypertension who underwent both 3D DCE MRA and endoscopy were reviewed retrospectively. All the patients were divided into bleeding group and non-bleeding group according to the clinical symptoms. The location and degree of the esophagogastric varices on 3D DCE MRA were assessed with postprocessing images, including subtraction, MIP and thin-slab masimum intensity projection (tin-MIP), and were compared with the results of endoscopy. The maximum, minimum and mean diameters of esophagogastric varices inside and outside of the wall were measured on the reformed images. The correlation between the findings of 3D DCE MRA and endoscopy were analyzed with Spearman rank correlation coefficient test. The rates of esophagogastric varices outside of the wall in bleeding and non-bleeding group were compared by means of Chi-square test. Results: In bleeding group, severe esophageal varices were documented in 59 patients, moderate in 6 patients, mild in 5 patients; in non-bleeding group, severe esophageal varices were documented in 32 patients, moderate in 4 patients, mild in 5 patients. Severe, moderate, and mild gastric varices were documented in 28, 34 and 16 in bleeding group, while they were 7, 12 and 9 in non-bleeding group. Esophageal and gastric varices can be wholly pressnted on MIP images after subtraction, while the esophagogastric varices inside and outside of the wall can be differentiated on thin-MIP images. The location and degree of esophagogastric varices on 3D DCE MRA were correlated with the findings of the endoscopy. The range of r was from 0.544 to 0.878 (P 2 =7.199, P<0.01). In 35 patients with severe gastric varices, 22 patients showed adventitial gastric varices in bleeding group (n=28) and 4 patients showed adventitial

  14. Multislice CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Prokop, Mathias E-mail: mathias.prokop@univie.ac.at

    2000-11-01

    Multislice CT has overcome past limitations of CT angiography (CTA): Scan length and spatial resolution can be simultaneously optimized with multislice CTA, contrast medium can be saved, and the evaluation of large anatomic areas and vessels smaller than 1 mm become possible. This article describes how to optimize scanning protocols and contrast injection, and discusses the main clinical applications of this new technique. Only three main scanning protocolssuffice for all indications. A high speed / high-volume protocol (using 4*2mm or 4*2.5mm collimation) can be employed to scan the chest or abdomen in 8-10s, or to cover the whole abdominal aorta and the peripheral runoff including the feet within 40-65s. A high resolution protocol (using 4*1mm or 4*1.25mm) can be employed for the aorta and most regional vascular beds. It allows for near isotrophic imaging and depicts fine vascular structures with excellent detail. Ultra-high resolution protocols (using 2*0.5mm or 4*0.5mm collimation) yield totally isotropic data sets, and are mainly reserved for cerebrovascular imaging. Image processing techniques, and, in particular, volume rendering have made image presentation faster and easier. Multislice CTA exceeds MRA in spatial resolution and is now able to display even small vascular side branches. Its main indications will be aortic diseases, suspected pulmonary embolism but also renal artery stenoses, preoperative workup of abdominal or cerebral vessels, and acute vascular diseases. Multisplice CTA will become a strong competitor of other minimally invasive vascular imaging techniques.

  15. Theory and X-ray Absorption Spectroscopy for Aluminum Coordination Complexes – Al K-Edge Studies of Charge and Bonding in (BDI)Al, (BDI)AlR2, and (BDI)AlX2 Complexes.

    Science.gov (United States)

    Altman, Alison B; Pemmaraju, C D; Camp, Clément; Arnold, John; Minasian, Stefan G; Prendergast, David; Shuh, David K; Tyliszczak, Tolek

    2015-08-19

    Polarized aluminum K-edge X-ray absorption near edge structure (XANES) spectroscopy and first-principles calculations were used to probe electronic structure in a series of (BDI)Al, (BDI)AlX2, and (BDI)AlR2 coordination compounds (X = F, Cl, I; R = H, Me; BDI = 2,6-diisopropylphenyl-β-diketiminate). Spectral interpretations were guided by examination of the calculated transition energies and polarization-dependent oscillator strengths, which agreed well with the XANES spectroscopy measurements. Pre-edge features were assigned to transitions associated with the Al 3p orbitals involved in metal-ligand bonding. Qualitative trends in Al 1s core energy and valence orbital occupation were established through a systematic comparison of excited states derived from Al 3p orbitals with similar symmetries in a molecular orbital framework. These trends suggested that the higher transition energies observed for (BDI)AlX2 systems with more electronegative X(1-) ligands could be ascribed to a decrease in electron density around the aluminum atom, which causes an increase in the attractive potential of the Al nucleus and concomitant increase in the binding energy of the Al 1s core orbitals. For (BDI)Al and (BDI)AlH2 the experimental Al K-edge XANES spectra and spectra calculated using the eXcited electron and Core-Hole (XCH) approach had nearly identical energies for transitions to final state orbitals of similar composition and symmetry. These results implied that the charge distributions about the aluminum atoms in (BDI)Al and (BDI)AlH2 are similar relative to the (BDI)AlX2 and (BDI)AlMe2 compounds, despite having different formal oxidation states of +1 and +3, respectively. However, (BDI)Al was unique in that it exhibited a low-energy feature that was attributed to transitions into a low-lying p-orbital of b1 symmetry that is localized on Al and orthogonal to the (BDI)Al plane. The presence of this low-energy unoccupied molecular orbital on electron-rich (BDI)Al distinguishes

  16. Iron deposition in the gray matter in patients with relapse-remitting multiple sclerosis: A longitudinal study using three-dimensional (3D)-enhanced T2*-weighted angiography (ESWAN)

    International Nuclear Information System (INIS)

    Du, Silin; Sah, Shambhu K.; Zeng, Chun; Wang, Jingjie; Liu, Yi; Xiong, Hua; Li, Yongmei

    2015-01-01

    Purpose: To investigate the relationship between the iron content by magnetic resonance imaging (MRI) and clinic correlation in patients with relapse-remitting multiple sclerosis (RRMS) over a two-year period. Methods: Thirty RRMS patients and 30 healthy control subjects were examined twice, two years apart, by undergoing brain conventional MRI and three-dimensional (3D)-enhanced T2*-weighted angiography (ESWAN) sequences at 3.0 T. Quantitative differences in iron content in deep gray matter (GM) nuclei and precentral gyrus GM between patients and control subjects with repeated-measures the mean phase values (MPVs) for ESWAN-filtered phase images. Spearman's rank correlation coefficient analysis was used to evaluate correlations of the MPVs, both 2-year-difference and single-time measurements, to disease duration, expanded disability status scale (EDSS) and times of recurrence. Results: The RRMS patients had higher GM iron concentration than that of the healthy control subjects in both single-time measurements, but only the substantia nigra (SN), and the precentral gyrus GM (PGM) showed a significant statistical difference (p < 0.05). Using the paired samples t test, we found that there were significant differences in two-year-difference measurements of the MPVs in the putamen (PUT), the globus pallidus (GP), the head of the caudate nucleus (HCN), the thalamus (THA), SN, the red nucleus (RN), the dentate nucleus (DN) and PGM, especially in SN (t = 2.92, p = 0.007) in RRMS patients. The MPVs of the PUT, GP, HCN, THA, SN, RN, DN and PGM for the subgroup with RRMS patients in times of recurrence less than twice were similar to the healthy controls. There was no significant difference in all regions of interests (ROIs). However, there were significant differences in all ROIs except THA and GP for the other subgroup with RRMS patients in times of recurrence more than and equal to twice. Spearman's rank correlation coefficient analysis showed there were

  17. Contrast-enhanced MR angiography of the carotid artery using 3D time-resolved imaging of contrast kinetics. Comparison with real-time fluoroscopic triggered 3D-elliptical centric view ordering

    International Nuclear Information System (INIS)

    Naganawa, Shinji; Koshikawa, Tokiko; Fukatsu, Hiroshi; Sakurai, Yasuo; Ishiguchi, Tsuneo; Ishigaki, Takeo; Ichinose, Nobuyasu

    2001-01-01

    The purpose of this study was to evaluate contrast-enhanced MR angiography using the 3D time-resolved imaging of contrast kinetics technique (3D-TRICKS) by direct comparison with the fluoroscopic triggered 3D-elliptical centric view ordering (3D-ELLIP) technique. 3D-TRICKS and 3D-ELLIP were directly compared on a 1.5-Tesla MR unit using the same spatial resolution and matrix. In 3D-TRICKS, the central part of the k-space is updated more frequently than the peripheral part of the k-space, which is divided in the slice-encoding direction. The carotid arteries were imaged using 3D-TRICKS and 3D-ELLIP sequentially in 14 patients. Temporal resolution was 12 sec for 3D-ELLIP and 6 sec for 3D-TRICKS. The signal-to-noise ratio (S/N) of the common carotid artery was measured, and the quality of MIP images was then scored in terms of venous overlap and blurring of vessel contours. No significant difference in mean S/N was seen between the two methods. Significant venous overlap was not seen in any of the patients examined. Moderate blurring of vessel contours was noted on 3D-TRICKS in five patients and on 3D-ELLIP in four patients. Blurring in the slice-encoding direction was slightly more pronounced in 3D-TRICKS. However, qualitative analysis scores showed no significant differences. When the spatial resolution of the two methods was identical, the performance of 3D-TRICKS was found to be comparable in static visualization of the carotid arteries with 3D-ELLIP, although blurring in the slice-encoding direction was slightly more pronounced in 3D-TRICKS. 3D-TRICKS is a more robust technique than 3D-ELLIP, because 3D-ELLIP requires operator-dependent fluoroscopic triggering. Furthermore, 3D-TRICKS can achieve higher temporal resolution. For the spatial resolution employed in this study, 3D-TRICKS may be the method of choice. (author)

  18. Iron deposition in the gray matter in patients with relapse-remitting multiple sclerosis: A longitudinal study using three-dimensional (3D)-enhanced T2*-weighted angiography (ESWAN)

    Energy Technology Data Exchange (ETDEWEB)

    Du, Silin, E-mail: 182389558@qq.com; Sah, Shambhu K., E-mail: mrsks2007@hotmail.com; Zeng, Chun, E-mail: zengchun19840305@163.com; Wang, Jingjie, E-mail: 345151097@qq.com; Liu, Yi, E-mail: 993537544@qq.com; Xiong, Hua, E-mail: rjdfxyh@163.com; Li, Yongmei, E-mail: lymzhang70@aliyun.com

    2015-07-15

    Purpose: To investigate the relationship between the iron content by magnetic resonance imaging (MRI) and clinic correlation in patients with relapse-remitting multiple sclerosis (RRMS) over a two-year period. Methods: Thirty RRMS patients and 30 healthy control subjects were examined twice, two years apart, by undergoing brain conventional MRI and three-dimensional (3D)-enhanced T2*-weighted angiography (ESWAN) sequences at 3.0 T. Quantitative differences in iron content in deep gray matter (GM) nuclei and precentral gyrus GM between patients and control subjects with repeated-measures the mean phase values (MPVs) for ESWAN-filtered phase images. Spearman's rank correlation coefficient analysis was used to evaluate correlations of the MPVs, both 2-year-difference and single-time measurements, to disease duration, expanded disability status scale (EDSS) and times of recurrence. Results: The RRMS patients had higher GM iron concentration than that of the healthy control subjects in both single-time measurements, but only the substantia nigra (SN), and the precentral gyrus GM (PGM) showed a significant statistical difference (p < 0.05). Using the paired samples t test, we found that there were significant differences in two-year-difference measurements of the MPVs in the putamen (PUT), the globus pallidus (GP), the head of the caudate nucleus (HCN), the thalamus (THA), SN, the red nucleus (RN), the dentate nucleus (DN) and PGM, especially in SN (t = 2.92, p = 0.007) in RRMS patients. The MPVs of the PUT, GP, HCN, THA, SN, RN, DN and PGM for the subgroup with RRMS patients in times of recurrence less than twice were similar to the healthy controls. There was no significant difference in all regions of interests (ROIs). However, there were significant differences in all ROIs except THA and GP for the other subgroup with RRMS patients in times of recurrence more than and equal to twice. Spearman's rank correlation coefficient analysis showed there were

  19. 3.0 Tesla high spatial resolution contrast-enhanced magnetic resonance angiography (CE-MRA) of the pulmonary circulation: initial experience with a 32-channel phased array coil using a high relaxivity contrast agent.

    Science.gov (United States)

    Nael, Kambiz; Fenchel, Michael; Krishnam, Mayil; Finn, J Paul; Laub, Gerhard; Ruehm, Stefan G

    2007-06-01

    To evaluate the technical feasibility of high spatial resolution contrast-enhanced magnetic resonance angiography (CE-MRA) with highly accelerated parallel acquisition at 3.0 T using a 32-channel phased array coil, and a high relaxivity contrast agent. Ten adult healthy volunteers (5 men, 5 women, aged 21-66 years) underwent high spatial resolution CE-MRA of the pulmonary circulation. Imaging was performed at 3 T using a 32-channel phase array coil. After intravenous injection of 1 mL of gadobenate dimeglumine (Gd-BOPTA) at 1.5 mL/s, a timing bolus was used to measure the transit time from the arm vein to the main pulmonary artery. Subsequently following intravenous injection of 0.1 mmol/kg of Gd-BOPTA at the same rate, isotropic high spatial resolution data sets (1 x 1 x 1 mm3) CE-MRA of the entire pulmonary circulation were acquired using a fast gradient-recalled echo sequence (TR/TE 3/1.2 milliseconds, FA 18 degrees) and highly accelerated parallel acquisition (GRAPPA x 6) during a 20-second breath hold. The presence of artifact, noise, and image quality of the pulmonary arterial segments were evaluated independently by 2 radiologists. Phantom measurements were performed to assess the signal-to-noise ratio (SNR). Statistical analysis of data was performed by using Wilcoxon rank sum test and 2-sample Student t test. The interobserver variability was tested by kappa coefficient. All studies were of diagnostic quality as determined by both observers. The pulmonary arteries were routinely identified up to fifth-order branches, with definition in the diagnostic range and excellent interobserver agreement (kappa = 0.84, 95% confidence interval 0.77-0.90). Phantom measurements showed significantly lower SNR (P < 0.01) using GRAPPA (17.3 +/- 18.8) compared with measurements without parallel acquisition (58 +/- 49.4). The described 3 T CE-MRA protocol in addition to high T1 relaxivity of Gd-BOPTA provides sufficient SNR to support highly accelerated parallel acquisition

  20. Fluorescence angiography in retinal tumours

    International Nuclear Information System (INIS)

    Fuhrmann, M.

    1980-01-01

    On the basis of the available photographic material the results of fluorescein angiography are reported in 4 cases of retinoblastoma and 3 cases of Bourneville's disease. The clinical diagnosis of retinoblastoma was confirmed histologically in all cases since the first eye had been removed for the same reason previously. One child had not yet been treated, and in 3 cases radioactive isotopes were used in the treatment. In the group of phacomatosis the patients had only periodical outpatient examinations. The importance of this angiography in the diagnosis and follow-up of these diseases is stressed. (author)

  1. Fluorescence angiography in retinal tumours

    Energy Technology Data Exchange (ETDEWEB)

    Fuhrmann, M [Staedtisches Klinikum Berlin-Buch (German Democratic Republic)

    1980-01-01

    On the basis of the available photographic material the results of fluorescein angiography are reported in 4 cases of retinoblastoma and 3 cases of Bourneville's disease. The clinical diagnosis of retinoblastoma was confirmed histologically in all cases since the first eye had been removed for the same reason previously. One child had not yet been treated, and in 3 cases radioactive isotopes were used in the treatment. In the group of phacomatosis the patients had only periodical outpatient examinations. The importance of this angiography in the diagnosis and follow-up of these diseases is stressed.

  2. Diagnosis of myocardial ischemia combining multiphase postmortem CT-angiography, histology, and postmortem biochemistry.

    Science.gov (United States)

    Vanhaebost, Jessica; Ducrot, Kewin; de Froidmont, Sébastien; Scarpelli, Maria Pia; Egger, Coraline; Baumann, Pia; Schmit, Gregory; Grabherr, Silke; Palmiere, Cristian

    2017-02-01

    The aim of this study was to assess whether the identification of pathological myocardial enhancement at multiphase postmortem computed tomography angiography was correlated with increased levels of troponin T and I in postmortem serum from femoral blood as well as morphological findings of myocardial ischemia. We further aimed to investigate whether autopsy cases characterized by increased troponin T and I concentrations as well as morphological findings of myocardial ischemia were also characterized by pathological myocardial enhancement at multiphase postmortem computed tomography angiography. Two different approaches were used. In one, 40 forensic autopsy cases that had pathological enhancement of the myocardium (mean Hounsfield units ≥95) observed at postmortem angiography were retrospectively selected. In the second approach, 40 forensic autopsy cases that had a cause of death attributed to acute myocardial ischemia were retrospectively selected. The preliminary results seem to indicate that the identification of a pathological enhancement of the myocardium at postmortem angiography is associated with the presence of increased levels of cardiac troponins in postmortem serum and morphological findings of ischemia. Analogously, a pathological enhancement of the myocardium at postmortem angiography can be retrospectively found in the great majority of autopsy cases characterized by increased cardiac troponin levels in postmortem serum and morphological findings of myocardial ischemia. Multiphase postmortem computed tomography angiography is a useful tool in the postmortem setting for investigating ischemically damaged myocardium.

  3. MDCT angiography and transcatheter embolization in management ...

    African Journals Online (AJOL)

    Hassan Abdelsalam

    2015-12-18

    Dec 18, 2015 ... 14 patients did not have a MDCT and proceeded straight to angiography;. 6 of them showed active bleeding on angiography. Conclusion: MDCT is an excellent technique before angiography and embolization in cases with acute gastrointestinal bleeding. Transcatheter embolization is an effective tool for ...

  4. Clinical application of pelvic MR angiography for gynecologic diseases

    Energy Technology Data Exchange (ETDEWEB)

    Ohnishi, Takeshi [Saint Marianna Univ., Kawasaki, Kanagawa (Japan). School of Medicine

    1996-08-01

    Magnetic resonance (MR) imaging is the second most important method next to the ultrasound for the diagnosis of gynecological disorders. MR angiography provides a new noninvasive method for evaluating vascular occlusive disease of the lower extremities and the branches of abdominal aorta. To our knowledge, no determinant of efficacy of MR angiography and images of gynecological diseases have yet been made. Maximum intensity projection image was obtained from the data set by the three dimensional contrast enhanced MR angiography (3D-CE MRA) with newly designed fat suppression method. MR angiogram reveals well visualization of lower abdominal aorta and its branches. Furthermore, uterine arteries were identified in 49.3% of the cases, branching from the internal iliac artery. Leiomyoma of the uterus showed an enhanced uterus in 53.7% of the eases. All cases of endometriosis demonstrated a homogeneous, high signal intensity being a specific finding. In conclusion, maximum intensity projection image of pelvis showed a good visualization of the lower abdominal aorta and its branches. Uterine artery and, in a few cases, ovarian artery can be demonstrated on MR angiography. All cases of endometriosis showed a significant, high signal intensity. This technique is noninvasive and be a supplementary method for diagnosis and follow up of vasculature of gynecological disorders. (author)

  5. Clinical application of pelvic MR angiography for gynecologic diseases

    International Nuclear Information System (INIS)

    Ohnishi, Takeshi

    1996-01-01

    Magnetic resonance (MR) imaging is the second most important method next to the ultrasound for the diagnosis of gynecological disorders. MR angiography provides a new noninvasive method for evaluating vascular occlusive disease of the lower extremities and the branches of abdominal aorta. To our knowledge, no determinant of efficacy of MR angiography and images of gynecological diseases have yet been made. Maximum intensity projection image was obtained from the data set by the three dimensional contrast enhanced MR angiography (3D-CE MRA) with newly designed fat suppression method. MR angiogram reveals well visualization of lower abdominal aorta and its branches. Furthermore, uterine arteries were identified in 49.3% of the cases, branching from the internal iliac artery. Leiomyoma of the uterus showed an enhanced uterus in 53.7% of the eases. All cases of endometriosis demonstrated a homogeneous, high signal intensity being a specific finding. In conclusion, maximum intensity projection image of pelvis showed a good visualization of the lower abdominal aorta and its branches. Uterine artery and, in a few cases, ovarian artery can be demonstrated on MR angiography. All cases of endometriosis showed a significant, high signal intensity. This technique is noninvasive and be a supplementary method for diagnosis and follow up of vasculature of gynecological disorders. (author)

  6. A study of the Nb3Ge system by Ge K-edge extended x-ray absorption fine structure and x-ray absorption near-edge structure spectroscopy

    International Nuclear Information System (INIS)

    Saini, N L; Filippi, M; Wu Ziyu; Oyanagi, H; Ihara, H; Iyo, A; Agrestini, S; Bianconi, A

    2002-01-01

    The local structure of Nb 3 Ge intermetallic superconductor has been studied by Ge K-edge absorption spectroscopy. Extended x-ray absorption fine structure (EXAFS) experiments show two Ge-Nb distances. In addition to the crystallographic distance of ∼2.87 A, there exists a second Ge-Nb distance, shorter than the first by ∼0.2 A, assigned to a phase with short-range symmetry related to local displacements in the Nb-Nb chains. The x-ray absorption near-edge structure (XANES) spectrum has been simulated by full multiple-scattering calculations considering the local displacements determined by the EXAFS analysis. The XANES spectrum has been well reproduced by considering a cluster of 99 atoms within a radius of about 7 A from the central Ge atom and introducing determined local displacements

  7. Evaluation of the relationship between extremity soft tissue sarcomas and adjacent major vessels using contrast-enhanced multidetector CT and three-dimensional volume-rendered CT angiography - A preliminary study

    International Nuclear Information System (INIS)

    Li, YangKang; Lin, JianBang; Cai, AiQun; Zhou, XiuGuo; Zheng, Yu; Wei, XiaoLong; Cheng, Ying; Liu, GuoRui

    2013-01-01

    Background: Accurate description of the relationship between extremity soft tissue sarcoma and the adjacent major vessels is crucial for successful surgery. In addition to magnetic resonance imaging (MRI) or in patients who cannot undergo MRI, two-dimensional (2D) postcontrast computed tomography (CT) images and three-dimensional (3D) volume-rendered CT angiography may be valuable alternative imaging techniques for preoperative evaluation of extremity sarcomas. Purpose: To preoperatively assess extremity sarcomas using multidetector CT (MDCT), with emphasis on postcontrast MDCT images and 3D volume-rendered MDCT angiography in evaluating the relationship between tumors and adjacent major vessels. Material and Methods: MDCT examinations were performed on 13 patients with non-metastatic extremity sarcomas. Conventional CT images and 3D volume-rendered CT angiography were evaluated, with focus on the relationship between tumors and adjacent major vessels. Kappa consistency statistics were performed with surgery serving as the reference standard. Results: The relationship between sarcomas and adjacent vessels was described as one of three patterns: proximity, adhesion, and encasement. Proximity was seen in five cases on postcontrast CT images or in eight cases on volume-rendered images. Adhesion was seen in three cases on both postcontrast CT images and volume-rendered images. Encasement was seen in five cases on postcontrast CT images or in two cases on volume-rendered images. Compared to surgical results, postcontrast CT images had 100% sensitivity, 83.3% specificity, 87.5% positive predictive value, 100% negative predictive value, and 92.3% accuracy in the detection of vascular invasion (κ = 0.843, P = 0.002). 3D volume-rendered CT angiography had 71.4% sensitivity, 100% specificity, 100% positive predictive value, 75% negative predictive value, and 84.6% accuracy in the detection of vascular invasion (κ = 0.698, P = 0.008). On volume-rendered images, all cases

  8. Digital subtraction angiography in traumatology

    International Nuclear Information System (INIS)

    Steudel, A.; Harder, T.; Lackner, K.; Schneider, B.; Orellano, L.; Bonn Univ.; Bonn Univ.

    1986-01-01

    The methods, indications and results of digital subtraction angiography in traumatology are presented, based on 56 examinations. The different use of intravenous or intraarterial DSA will be discussed with respect to expanding and localisation of traumatic vascular injury. DSA is recommended as the method of choice for follow-up after vascular reconstructive procedure. (orig.) [de

  9. MR angiography of the iliofemoral artery system

    International Nuclear Information System (INIS)

    Steffens, J.C.; Link, J.; Brinkmann, G.; Reuter, M.; Heller, M.

    1997-01-01

    During the last years, magnetic resonance angiography (MRA) has become a widely used modality for intracerebral and carotid artery imaging. Due to technical limitations, the clinical impact of MRA in the iliofemoral arteries has been rather poor. New developments in MRA like ECG-triggered sequences and the occurrence of contrast-enhanced MRA has overcome most of these limitations. Therefore, a major advance in clinical use of these diagnostic tools can be predicted. This paper discussed the advantages of ECG-gated 2D-Phase contrast, ECG-gated 2D-Time-of-Flight and contrast enhanced FLASH 3D angiography sequences from a clinical point of view. 2D-PC-MRA is a robust technique, which provides an overview of the iliofemoral artery system in less than 5 minutes. Limitations are the true 2D impression of the sequence and the partial venous overlay. 2D-TOF-MRA on the other hand is time consuming, however it enables 3D reconstruction and effective venous suppression can be applied. Contrast enhanced MRA as the third sequence discussed provides high resolution images in less than 30 sec. However contrast bolus timing might be a problem. In conclusion the authors suggest a combination of 2D-PC-MRA and additional 2D-TOF sequences at questionable vacular areas as the modality of choice, due to the fact, that MRA of the iliofemoral arteries is mostly only one step of a complete lower limb examination. Contrast MRA might become the method of choice in the future however problems with multiple contrast injections and upper limits of contrast dose have to be solved. (orig.) [de

  10. Risk of renal allograft rejection following angiography

    International Nuclear Information System (INIS)

    Heideman, M.; Claes, G.; Nilson, A.E.

    1976-01-01

    In a retrospective study of 173 immediately functioning primary kidney transplants, correlation between angiography and renal allograft rejection was studied during the first 14 days. It was found that rejection was more frequent in kidneys undergoing angiography than in those not undergoing angiography. It was also found that in kidneys undergoing angiography an overwhelming number of the rejections started the day after angiography. These differences in rejection frequency could not be explained by differences in HLA matching or the origin of the kidneys. These findings suggest a possible connection indicating that the angiography might elicit an acute rejection episode. A possible mechanism for starting this reaction might be activation of the complement system which was found in 50 percent of the patients undergoing angiography in peripheral blood and in 100 percent when studied in vitro

  11. E-learn Computed Tomographic Angiography

    DEFF Research Database (Denmark)

    Havsteen, Inger; Christensen, Anders; Nielsen, Jens K

    2012-01-01

    BACKGROUND: Computed tomographic angiography (CTA) is widely available in emergency rooms to assess acute stroke patients. To standardize readings and educate new readers, we developed a 3-step e-learning tool based on the test-teach-retest methodology in 2 acute stroke scenarios: vascular...... occlusion and "spot sign" in acute intracerebral hemorrhage. We hypothesized that an e-learning program enhances reading skills in physicians of varying experience. METHODS: We developed an HTML-based program with a teaching segment and 2 matching test segments. Tests were taken before and after...... sign correctly 69% before versus 92% after teaching (P = .009) and reported a median self-perceived diagnostic certainty of 50% versus 75% (P = .030). Self-perceived diagnostic certainty revealed no significant increase for vascular occlusion. CONCLUSIONS: The e-learning program is a useful educational...

  12. Is fasting necessary for elective cerebral angiography?

    Science.gov (United States)

    Kwon, O-K; Oh, C W; Park, H; Bang, J S; Bae, H-J; Han, M K; Park, S-H; Han, M H; Kang, H-S; Park, S-K; Whang, G; Kim, B-C; Jin, S-C

    2011-05-01

    In order to prevent unexpected events such as aspiration pneumonia, cerebral angiography has been performed under fasting in most cases. We investigated prospectively the necessity of fasting before elective cerebral angiography. The study is an open-labeled clinical trial without random allocation. In total, 2554 patients who underwent elective cerebral angiography were evaluated on development of nausea, vomiting, and pulmonary aspiration during and after angiography. Potential risks and benefits associated with fasting were provided in written documents and through personal counseling to patients before the procedure. The patients chose their fasting or nonfasting option. No restriction in diet was given after angiography. The patients were observed for 24 hours. Nausea and vomiting during and within 1 hour after angiography was considered as a positive event associated with cerebral angiography. The overall incidence of nausea and vomiting during and within 1 hour after angiography was 1.05% (27/2554 patients). There was no patient with pulmonary aspiration. No statistical difference in nausea and vomiting development between the fasting and the diet groups was found. The incidence of nausea and vomiting associated with cerebral angiography is low and not affected by diet or fasting. Pulmonary aspiration had no difference between the diet and the fasting group. Our study suggests that fasting may not be necessary for patients who undergo elective cerebral angiography.

  13. Multiple rare-earth ion environments in amorphous (Gd2O3)0.230(P2O5)0.770 revealed by gadolinium K-edge anomalous X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Cole, Jacqueline M.; Cramer, Alisha J.; Shastri, Sarvjit D.; Mukaddem, Karim T.; Newport, Robert J

    2018-04-26

    A Gd K-edge anomalous X-ray scattering (AXS) study is performed on the rare-earth (R) phosphate glass, (Gd2O3)0.230(P2O5)0.770, in order to determine Gd…Gd separations in its local structure. The minimum rare-earth separation is of particular interest given that the optical properties of these glasses can quench when rare-earth ions become too close to each other. To this end, a weak Gd…Gd pairwise correlation is located at 4.2(1) Å which is representative of a meta-phosphate R…R separation. More intense first neighbor Gd…Gd pairwise correlations are found at the larger radial distributions, 4.8(1) Å, 5.1(1) Å and 5.4(1) Å. These reflect a mixed ultra-phosphate and meta-phosphate structural character, respectively. A second neighbor Gd…Gd pairwise correlation lies at 6.6(1) Å which is indicative of meta-phosphate structures. Meta- and ultra-phosphate classifications are made by comparing the R…R separations against those of rare-earth phosphate crystal structures, R(PO3)3 and RP5O14 respectively, or difference pair distribution function (PDF) features determined on similar glasses using difference neutron scattering methods. The local structure of this glass is therefore found to display multiple rare-earth ion environments, presumably because its composition lies between these two stoichiometric formulae. These Gd…Gd separations are well resolved in the PDFs that represent the AXS signal. Indeed, the spatial resolution is so good that it also enables the identification of R…X (X = R, P, O) pairwise correlations up to r ~ 9 Å; their average separations lie at r ~ 7.1(1) Å, 7.6(1) Å 7.9(1) Å, 8.4(1) Å and 8.7(1) Å. This is the first report of a Gd K-edge AXS study on an amorphous material. Its demonstrated ability to characterize the local structure of a glass up to such a long-range of r, heralds exciting prospects for AXS studies on other ternary non-crystalline materials. However, the technical challenge of such an experiment

  14. Electrocardiographically gated snapshot MR angiography

    International Nuclear Information System (INIS)

    Brown, D.G.; Holsinger, A.E.; Riederer, S.J.

    1990-01-01

    The purpose of this paper is to evaluate the effectiveness of applying ultrashort (∼12 msec) TR times and measuring the central phase encodings first in improving the accuracy of vascular depiction in MR angiography. The imaging method combines ultrashort TR imaging techniques with time-of-flight MR angiography. The central phase-encoding views are acquired first, and an inversion-recovery contrast preparation pulse is applied prior to image acquisition to null signal from static tissues. In initial studies, the method was tested on phantoms and volunteers. The contrast-preparation phase effectively nulls static spins at the start of image acquisition. During the TL period fresh blood flows into the imaging section; even slowly moving blood is fully replaced

  15. Pulmonary angiography with lopamidol 370

    International Nuclear Information System (INIS)

    Braun, S.D.; Saeed, M.; Perlmutt, L.M.; Newman, G.E.; Illescas, F.F.; Cohan, R.H.; Dunnick, N.R.

    1986-01-01

    Fifty-one consecutive patients who underwent pulmonary angiography with iopamidol, 370 mg/ml, were studied prospectively. Patients were asked to grade any heat or pain felt on injection, and were observed for coughing. Right atrial and pulmonary artery pressures were obtained before the first and after the final contrast agent injection. Pressure changes were compared with those in a consecutive group of 25 patients who underwent examinations performed with Na-meglumine diatrizoate, 370 mg/ml. Film quality was evaluated for patient motion. Iopamidol generated marked discomfort in only three patients. Pressure changes were largely unremarkable. In no case was there any significant motion artifact secondary to coughing. Iopamidol is a safe, well-tolerated contrast agent for pulmonary angiography. It improves image quality by nearly eliminating coughing

  16. Using solution- and solid-state S K-edge X-ray absorption spectroscopy with density functional theory to evaluate M-S bonding for MS4(2-) (M = Cr, Mo, W) dianions.

    Science.gov (United States)

    Olson, Angela C; Keith, Jason M; Batista, Enrique R; Boland, Kevin S; Daly, Scott R; Kozimor, Stosh A; MacInnes, Molly M; Martin, Richard L; Scott, Brian L

    2014-12-14

    Herein, we have evaluated relative changes in M-S electronic structure and orbital mixing in Group 6 MS4(2-) dianions using solid- and solution-phase S K-edge X-ray absorption spectroscopy (XAS; M = Mo, W), as well as density functional theory (DFT; M = Cr, Mo, W) and time-dependent density functional theory (TDDFT) calculations. To facilitate comparison with solution measurements (conducted in acetonitrile), theoretical models included gas-phase calculations as well as those that incorporated an acetonitrile dielectric, the latter of which provided better agreement with experiment. Two pre-edge features arising from S 1s → e* and t electron excitations were observed in the S K-edge XAS spectra and were reasonably assigned as (1)A1 → (1)T2 transitions. For MoS4(2-), both solution-phase pre-edge peak intensities were consistent with results from the solid-state spectra. For WS4(2-), solution- and solid-state pre-edge peak intensities for transitions involving e* were equivalent, while transitions involving the t orbitals were less intense in solution. Experimental and computational results have been presented in comparison to recent analyses of MO4(2-) dianions, which allowed M-S and M-O orbital mixing to be evaluated as the principle quantum number (n) for the metal valence d orbitals increased (3d, 4d, 5d). Overall, the M-E (E = O, S) analyses revealed distinct trends in orbital mixing. For example, as the Group 6 triad was descended, e* (π*) orbital mixing remained constant in the M-S bonds, but increased appreciably for M-O interactions. For the t orbitals (σ* + π*), mixing decreased slightly for M-S bonding and increased only slightly for the M-O interactions. These results suggested that the metal and ligand valence orbital energies and radial extensions delicately influenced the orbital compositions for isoelectronic ME4(2-) (E = O, S) dianions.

  17. Angiography of the upper extremity

    International Nuclear Information System (INIS)

    Janevski, B.K.

    1982-01-01

    This thesis provides a description of the technical and medical aspects of arteriography of the upper extremity and an extensive analysis of the angiographic anatomy and pathology of 750 selective studies performed in more than 500 patients. A short historical review is provided of angiography as a whole and of arteriography of the hand in particular. The method of percutaneous transfemoral catheterization of the arteries of the upper extremity and particularly the arteries of the hand is considered, discussing the problems the angiographer encounters frequently, describing the angiographic complications which may occur and emphasizing the measures to keep them to a minimum. The use of vasodilators in hand angiography is discussed. A short description of the embryological patterns persisting in the arteries of the arm is included in order to understand the congenital variations of the arteries of the upper extremity. The angiographic patterns and clinical aspects of the most common pathological processes involving the arteries of the upper extremities are presented. Special attention is paid to the correlation between angiography and pathology. (Auth.)

  18. Hemifacial spasm; The value of vertebral angiography

    International Nuclear Information System (INIS)

    Yang, Hak Seok; Kim, Myung Soon; Han, Yong Pyo

    1992-01-01

    In order to evaluate the value of vertebral angiography in assesment of hemifacial spasm, We reviewed retrospectively the vertebral angiography of 28 patients (30 cases) with surgically proved hemifacial spasm but normal CT scans of posterior fossa. There were 9 males and 19 females. Angiography revealed vascular focus of hemifacial spasm located at anterior inferior cerebellar artery , posterior inferior cerebellar artery, and vertebral artery in 19, 9, and 2 cases respectively. Right side was involved in 20 cases. All involved vessels were elongated, tortuous, and dilated. In conclusion, vertebral angiography was valuable in evaluating hemifacial spasm of vascular origin in the posterior fossa

  19. Fe K-Edge X-ray absorption near-edge spectroscopy (XANES) and X-ray diffraction (XRD) analyses of LiFePO4 and its base materials

    Science.gov (United States)

    Latif, C.; Negara, V. S. I.; Wongtepa, W.; Thamatkeng, P.; Zainuri, M.; Pratapa, S.

    2018-03-01

    XANES analysis has been performed with the aim of knowing the Fe oxidation state in a synthesized LiFePO4 and its base materials. XANES measurements were performed at SLRI on energy around Fe K-edge. An XRD analysis has also been performed with the aim of knowing the phase composition, lattice parameters and crystallite size of the LiFePO4 as well as the base materials. From the XRD analysis, it was found that the dominating phase in the iron sand sample was Fe3O4 and the only phase found after calcination was LiFePO4. The latter phase exhibited crystallite size of 100 nm and lattice parameters a = 10.169916 Å, b = 5.919674 Å, c = 4.627893 Å. Qualitative analysis of XANES data revealed that the oxidation number of Fe in the sample before calcination was greater than that after calcination and Fe in the natural iron sand, indicated by the E0 values of 7129.2 eV, 7120.6 eV and 7124.4 eV respectively.

  20. Chemical kinetics of Cs species in an alkali-activated municipal solid waste incineration fly ash and pyrophyllite-based system using Cs K-edge in situ X-ray absorption fine structure analysis

    Science.gov (United States)

    Shiota, Kenji; Nakamura, Takafumi; Takaoka, Masaki; Nitta, Kiyofumi; Oshita, Kazuyuki; Fujimori, Takashi; Ina, Toshiaki

    2017-05-01

    We conducted in situ X-ray absorption fine structure (in situ XAFS) analysis at the Cs K-edge to investigate the chemical kinetics of Cs species during reaction in an alkali-activated municipal solid waste incineration fly ash (MSWIFA) and pyrophyllite-based system. Understanding the kinetics of Cs is essential to the design of appropriate conditions for Cs stabilization. In situ XAFS analysis of four pastes, prepared from NaOHaq, sodium silicate solution, pyrophyllite, and MSWIFA with the addition of CsCl, was conducted in custom-built reaction cells at four curing temperatures (room temperature, 60 °C, 80 °C, 105 °C) for approximately 34 h. The results indicated that the change in Cs species during reaction at room temperature was small, while changes at higher temperatures were faster and more extreme, with the fastest conversion to pollucite occurring at 105 °C. Further analysis using a leaching test and a simple reaction model for Cs species during reaction showed that the pollucite formation rate was dependent on the curing temperature and had a significant negative correlation with Cs leaching. The activation energy of pollucite formation was estimated to be 31.5 kJ/mol. These results revealed that an important change in the chemical state of Cs occurs during reaction in the system.

  1. Benefit of cone-beam computed tomography angiography in acute management of angiographically undetectable ruptured arteriovenous malformations.

    Science.gov (United States)

    Rahal, Jason P; Malek, Adel M

    2013-10-01

    Ruptured arteriovenous malformations (AVMs) are a frequent cause of intracerebral hemorrhage (ICH). In some cases, compression from the associated hematoma in the acute setting can partially or completely occlude an AVM, making it invisible on conventional angiography techniques. The authors report on the successful use of cone-beam CT angiography (CBCT-A) to precisely identify the underlying angioarchitecture of ruptured AVMs that are not visible on conventional angiography. Three patients presented with ICH for which they underwent examination with CBCT-A in addition to digital subtraction angiography and other imaging modalities, including MR angiography and CT angiography. All patients underwent surgical evacuation due to mass effect from the hematoma. Clinical history, imaging studies, and surgical records were reviewed. Hematoma volumes were calculated. In all 3 cases, CBCT-A demonstrated detailed anatomy of an AVM where no lesion or just a suggestion of a draining vein had been seen with other imaging modalities. Magnetic resonance imaging demonstrated enhancement in 1 patient; CT angiography demonstrated a draining vein in 1 patient; 2D digital subtraction angiography and 3D rotational angiography demonstrated a suggestion of a draining vein in 2 cases and no finding in the third. In the 2 patients in whom CBCT-A was performed prior to surgery, the demonstrated AVM was successfully resected without evidence of a residual lesion. In the third patient, CBCT-A allowed precise targeting of the AVM nidus using Gamma Knife radiosurgery. Cone-beam CT angiography should be considered in the evaluation and subsequent treatment of ICH due to ruptured AVMs. In cases in which the associated hematoma compresses the AVM nidus, CBCT-A can have higher sensitivity and anatomical accuracy than traditional angiographic modalities, including digital subtraction angiography.

  2. A study of transverse image reconstruction with digital subtraction angiography

    International Nuclear Information System (INIS)

    Sakamoto, Kiyoshi; Kotoura, Noriko; Terasawa, Yuuji; Oda, Masahiko; Gotou, Hiroshi; Nasada, Toshiya; Tanooka, Masao

    1995-01-01

    For digital subtraction angiography (DSA) with C-type equipment, it is possible to radiate an X-ray during rotation and to collect data at different angular settings. We tried to reconstruct transverse image from data obtained by scanning DSA images at different angular settings. 88 projection data were obtained by rotating the object at 180deg during radiation. Reconstruction was made using the convolution method with pixel value distribution for each projection. Similarly, the image quality of the reconstructed images were compared with the unsubtracted and subtracted ones. In case a part object was outside the calculating region, artifacts were generally produced. However, the artifacts were reduced by subtracting the background from the image. In addition, the cupping phenomenon caused by beam hardening was relaxed and high-quality imaging could be achieved. This method will become even more effective, if we will use it with selective angiography in which the limited area is enhanced. (author)

  3. Spiral CT angiography of renal arteries: comparison with angiography

    International Nuclear Information System (INIS)

    Wittenberg, G.; Kenn, W.; Tschammler, A.; Sandstede, J.; Hahn, D.

    1999-01-01

    A prospective study was carried out to determine the accuracy of spiral CT angiography (CTA) in the detection of renal artery stenosis (RAS). Eighty-two patients with arterial hypertension underwent CTA and digital subtraction angiography (DSA) to exclude RAS. For CTA a contrast medium bolus of 100-150 ml (flow rate 3 ml/s) was injected. A 24 or 40 s CTA was started at the origin of the superior mesenteric artery after a delay time determined by test bolus injection (collimation = 2 mm, pitch = 1/1.5). For stenosis detection transverse images supported by maximum intensity projections (MIP) or multiplanar reconstruction projections were used. Of 197 renal arteries examined (including 33 accessory arteries), 34 RAS were visualized using DSA. With CTA, one hemodynamic RAS was missed and one additional hemodynamic RAS was found. Sensitivity/specificity was calculated to be 94 %/98 %. For hemodynamically relevant RAS (> 50 %) the sensitivity/specificity was 96 %/99 %. CTA additionally depicted five adrenal masses. The high accuracy rate of RAS detection thus allows the use of CTA as a screening method in patients with arterial hypertension to exclude a renovascular cause. (orig.)

  4. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    Medline Plus

    Full Text Available ... Sponsored by Image/Video Gallery Your Radiologist Explains Magnetic Resonance Angiography (MRA) Transcript Welcome to Radiology Info dot ... I’d like to talk with you about magnetic resonance angiography, or as it’s commonly known, MRA. MRA ...

  5. Exercise intravenous digital subtraction angiography

    International Nuclear Information System (INIS)

    Yiannikas, J.

    1986-01-01

    Attempts to use exercise ventriculography have been made, not only to give diagnostic and perhaps even prognostic information in patients with coronary artery disease, but also in patients with valvular heart disease both before and after surgical intervention. Clearly an accurate method of assessing ventricular function under conditions of stress in various cardiac diseases would provide important information that would help in patient management. Exercise ventriculography using gated blood pool equilibrium technetium studies are widely used, but are limited by spatial resolution and by the foreshortening affects of visualizing the left ventricular chamber in the left anterior oblique view. First pass radionuclide studies have the added advantage of being able to visualize the ventricular chamber in the anterior or even the right anterior oblique view, but are even more limited by their spatial resolution problems. Several investigations have shown that digital subtraction angiography produces left ventricular images with a spatial resolution almost identical to that of conventional contrast ventriculography, but without the inherent problems of cardiac arrhythmias, which often limit the assessment of left ventricular function. Because of its ability to accurately delineate wall motion abnormalities, the technique may provide an adequate assessment of global and regional left ventricular function after exercise. Digital subtraction angiography may identify ischemic wall motion abnormalities produced by exercise in patients who already had significant permanent left ventricular damage from myocardial infarction

  6. Characterization of rust layer formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich environment by Cl and Fe K-edge XANES measurements

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2005-01-01

    Chloride in atmosphere considerably reduces the corrosion resistance of conventional weathering steel containing a small amount of Cr. Ni is an effective anticorrosive element for improving the corrosion resistance of steel in a Cl-rich environment. In order to clarify the structure of the protective rust layer of weathering steel, Cl and Fe K-edge X-ray absorption near edge structure (XANES) spectra of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich atmosphere were measured. The Fe K-XANES measurements enable the characterization of mixture of iron oxides such as rust. The chemical composition of the rust was determined by performing pattern fitting of the measured spectra. All the rust is composed mainly of goethite, akaganeite, lepidocrocite and magnetite. Among these iron oxides, akaganeite in particular is the major component in the rust. Additionally, the amount of akaganeite in the rust of Fe-Ni alloy is much greater than that in rust of Fe-Cr alloy. Akaganeite is generally considered to facilitate the corrosion of steel, but our results indicate that akaganeite in the rust of Fe-Ni alloy is quantitatively different from that in rust of Fe-Cr alloy and does not facilitate the corrosion of steel. The shoulder peak observed in Cl K-XANES spectra reveals that the rust contains a chloride other than akaganeite. The energy of the shoulder peak does not correspond to that of any well-known chlorides. In the measured spectra, there is no proof that Cl, by combining with the alloying element, inhibits the alloying element from acting in corrosion resistance. The shoulder peak appears only when the content of the alloying element is lower than a certain value. This suggests that the generation of the unidentified chloride is related to the corrosion rate of steel. (author)

  7. Acoustic Angiography: A New Imaging Modality for Assessing Microvasculature Architecture

    Directory of Open Access Journals (Sweden)

    Ryan C. Gessner

    2013-01-01

    Full Text Available The purpose of this paper is to provide the biomedical imaging community with details of a new high resolution contrast imaging approach referred to as “acoustic angiography.” Through the use of dual-frequency ultrasound transducer technology, images acquired with this approach possess both high resolution and a high contrast-to-tissue ratio, which enables the visualization of microvascular architecture without significant contribution from background tissues. Additionally, volumetric vessel-tissue integration can be visualized by using b-mode overlays acquired with the same probe. We present a brief technical overview of how the images are acquired, followed by several examples of images of both healthy and diseased tissue volumes. 3D images from alternate modalities often used in preclinical imaging, contrast-enhanced micro-CT and photoacoustics, are also included to provide a perspective on how acoustic angiography has qualitatively similar capabilities to these other techniques. These preliminary images provide visually compelling evidence to suggest that acoustic angiography may serve as a powerful new tool in preclinical and future clinical imaging.

  8. Time-resolved CT angiography in aortic dissection

    International Nuclear Information System (INIS)

    Meinel, Felix G.; Nikolaou, Konstantin; Weidenhagen, Rolf; Hellbach, Katharina; Helck, Andreas; Bamberg, Fabian; Reiser, Maximilian F.; Sommer, Wieland H.

    2012-01-01

    Objectives: We performed this study to assess feasibility and additional diagnostic value of time-resolved CT angiography of the entire aorta in patients with aortic dissection. Materials and methods: 14 consecutive patients with known or suspected aortic dissection (aged 60 ± 9 years) referred for aortic CT angiography were scanned on a dual-source CT scanner (Somatom Definition Flash; Siemens, Forchheim, Germany) using a shuttle mode for multiphasic image acquisition (range 48 cm, time resolution 6 s, 6 phases, 100 kV, 110 mAs/rot). Effective radiation doses were calculated from recorded dose length products. For all phases, CT densities were measured in the aortic lumen and renal parenchyma. From the multiphasic data, 3 phases corresponding to a triphasic standard CT protocol, served as a reference and were compared against findings from the time-resolved datasets. Results: Mean effective radiation dose was 27.7 ± 3.5 mSv. CT density of the true lumen peaked at 355 ± 53 HU. Compared to the simulated triphasic protocol, time-resolved CT angiography added diagnostic information regarding a number of important findings: the enhancement delay between true and false lumen (n = 14); the degree of membrane oscillation (n = 14); the perfusion delay in arteries originating from the false lumen (n = 9). Other additional information included true lumen collapse (n = 4), quantitative assessment of renal perfusion asymmetry (n = 2), and dynamic occlusion of aortic branches (n = 2). In 3/14 patients (21%), these additional findings of the multiphasic protocol altered patient management. Conclusions: Multiphasic, time-resolved CT angiography covering the entire aorta is feasible at a reasonable effective radiation dose and adds significant diagnostic information with therapeutic consequences in patients with aortic dissection.

  9. Magnetic resonance angiography of arteriovenous malformation in the brainstem

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Hirofumi; Kida, Yoshihisa; Kobayashi, Tatsuya; Tanaka, Takayuki; Iwakoshi, Takayasu; Kai, Osamu; Hirose, Mitsuhiko [Komaki City Hospital, Aichi (Japan)

    1993-11-01

    The magnetic resonance (MR) angiography appearance of arteriovenous malformation (AVM) in the tegmentum and pons is described. The interpeduncular perforating branches of the posterior cerebral artery and median pontine branches of the basilar artery were seen more clearly by MR angiography than by conventional angiography. MR angiography was very useful for the follow-up of AVM after stereotactic radiosurgery. (author).

  10. Digital subtraction angiography of the heart and lungs

    International Nuclear Information System (INIS)

    Moodie, D.S.; Yiannikas, J.

    1986-01-01

    This book contains 12 chapters. Some of the chapter titles are: Physical Principles of Cardiac Digital Subtraction Angiography, The Use of Intravenous Digital Subtraction Angiography in Evaluating Patients with Complex Congenital Heart Disease, Exercise Intravenous Digital Subtraction Angiograpny, Cardiomyopathic and Cardiac Neoplastic Disease, Digital Subtraction Angiography in the Catheterization Laboratory, and Cardiac Digital Subtraction Angiography - Future Directions

  11. Preoperative evaluation of the artery of adamkiewicz by MR angiography and CT angiography in patients with a thoracic aortic aneurysm

    International Nuclear Information System (INIS)

    Niinuma, Hiroyuki; Ohira, Atsushi; Makita, Shinji; Moriai, Yoshiteru; Hiramori, Katsuhiko; Yoshioka, Kunihiro; Nakajima, Takayuki; Kawazoe, Kohei

    2002-01-01

    Paraplegia is known as an extremely serious and important complication of surgical repair in patients with a thoraco-abdominal aortic aneurysm. It is important to evaluate the artery of Adamkiewicz (AdA) before surgical repair to prevent paraplegia. But the AdA is difficult to visualize by the invasive and hazardous, conventional selective angiography. The aim of this study was to visualize AdA by MR angiography (MRA) and CT angiography (CTA). Twenty-one consecutive patients with a thoracic aortic aneurysm underwent both gadolinium-enhanced, three-dimensional MRA and CTA using multislice helical CT. The AdA was successfully visualized in 15 of the 21 patients (71.4%) by MRA, and in 17 of those 21 patients (8