TY - JOUR A1 - Becker, Meike A1 - Frauenrath, Tobias A1 - Hezel, Fabian A1 - Krombach, Gabriele A. A1 - Kremer, Ute A1 - Koppers, Benedikt A1 - Butenweg, Christoph A1 - Goemmel, Andreas A1 - Utting, Jane F. A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf T1 - Comparison of left ventricular function assessment using phonocardiogram- and electrocardiogram-triggered 2D SSFP CINE MR imaging at 1.5 T and 3.0 T JF - European Radiology N2 - Objective: As high-field cardiac MRI (CMR) becomes more widespread the propensity of ECG to interference from electromagnetic fields (EMF) and to magneto-hydrodynamic (MHD) effects increases and with it the motivation for a CMR triggering alternative. This study explores the suitability of acoustic cardiac triggering (ACT) for left ventricular (LV) function assessment in healthy subjects (n=14). Methods: Quantitative analysis of 2D CINE steady-state free precession (SSFP) images was conducted to compare ACT’s performance with vector ECG (VCG). Endocardial border sharpness (EBS) was examined paralleled by quantitative LV function assessment. Results: Unlike VCG, ACT provided signal traces free of interference from EMF or MHD effects. In the case of correct Rwave recognition, VCG-triggered 2D CINE SSFP was immune to cardiac motion effects—even at 3.0 T. However, VCG-triggered 2D SSFP CINE imaging was prone to cardiac motion and EBS degradation if R-wave misregistration occurred. ACT-triggered acquisitions yielded LV parameters (end-diastolic volume (EDV), endsystolic volume (ESV), stroke volume (SV), ejection fraction (EF) and left ventricular mass (LVM)) comparable with those derived fromVCG-triggered acquisitions (1.5 T: ESVVCG=(56± 17) ml, EDVVCG=(151±32)ml, LVMVCG=(97±27) g, SVVCG=(94± 19)ml, EFVCG=(63±5)% cf. ESVACT= (56±18) ml, EDVACT=(147±36) ml, LVMACT=(102±29) g, SVACT=(91± 22) ml, EFACT=(62±6)%; 3.0 T: ESVVCG=(55±21) ml, EDVVCG=(151±32) ml, LVMVCG=(101±27) g, SVVCG=(96±15) ml, EFVCG=(65±7)% cf. ESVACT=(54±20) ml, EDVACT=(146±35) ml, LVMACT= (101±30) g, SVACT=(92±17) ml, EFACT=(64±6)%). Conclusions: ACT’s intrinsic insensitivity to interference from electromagnetic fields renders KW - Magnetic resonance imaging (MRI) KW - MR-stethoscope KW - Magnetic field strength KW - Left ventriular function KW - Cardiovascular MRI Y1 - 2010 U6 - http://dx.doi.org/10.1007/s00330-009-1676-z SN - 1432-1084 (Onlineausgabe) SN - 0938-7994 (Druckausgabe) VL - 20 SP - 1344 EP - 1355 PB - Springer CY - Berlin ER - TY - JOUR A1 - Esch, Thomas T1 - Trends in commercial vehicle powertrains JF - ATZautotechnology N2 - Low emission zones and truck bans, the rising price of diesel and increases in road tolls: all of these factors are putting serious pressure on the transport industry. Commercial vehicle manufacturers and their suppliers are in the process of identifying new solutions to these challenges as part of their efforts to meet the EEV (enhanced environmentally friendly vehicle) limits, which are currently the most robust European exhaust and emissions standards for trucks and buses. KW - European Transient Cycle KW - Common Rail Injection System KW - Commercial Vehicle KW - Selective Catalytic Reduction KW - Diesel Engine Y1 - 2010 U6 - http://dx.doi.org/10.1007/BF03247185 SN - 2192-886X VL - 2010 IS - 10 SP - 26 EP - 31 PB - Vieweg & Sohn CY - Wiesbaden ER - TY - JOUR A1 - Czarnecki, Christian A1 - Winkelmann, Axel A1 - Spiliopoulou, Myra T1 - Services in electronic telecommunication markets: a framework for planning the virtualization of processes JF - Electronic Markets N2 - The potential of electronic markets in enabling innovative product bundles through flexible and sustainable partnerships is not yet fully exploited in the telecommunication industry. One reason is that bundling requires seamless de-assembling and re-assembling of business processes, whilst processes in telecommunication companies are often product-dependent and hard to virtualize. We propose a framework for the planning of the virtualization of processes, intended to assist the decision maker in prioritizing the processes to be virtualized: (a) we transfer the virtualization pre-requisites stated by the Process Virtualization Theory in the context of customer-oriented processes in the telecommunication industry and assess their importance in this context, (b) we derive IT-oriented requirements for the removal of virtualization barriers and highlight their demand on changes at different levels of the organization. We present a first evaluation of our approach in a case study and report on lessons learned and further steps to be performed. KW - Telecommunication KW - Services KW - Process virtualization KW - Product bundling KW - Transformation Y1 - 2010 U6 - http://dx.doi.org/10.1007/s12525-010-0045-8 SN - 1422-8890 VL - 20 IS - 3-4 SP - 197 EP - 207 PB - Springer CY - Berlin ER - TY - JOUR A1 - Grajewski, Matthias A1 - Köster, Michael A1 - Turek, Stefam T1 - Numerical analysis and implementational aspects of a new multilevel grid deformation method JF - Applied Numerical Mathematics N2 - Recently, we introduced and mathematically analysed a new method for grid deformation (Grajewski et al., 2009) [15] we call basic deformation method (BDM) here. It generalises the method proposed by Liao et al. (Bochev et al., 1996; Cai et al., 2004; Liao and Anderson, 1992) [4], [6], [20]. In this article, we employ the BDM as core of a new multilevel deformation method (MDM) which leads to vast improvements regarding robustness, accuracy and speed. We achieve this by splitting up the deformation process in a sequence of easier subproblems and by exploiting grid hierarchy. Being of optimal asymptotic complexity, we experience speed-ups up to a factor of 15 in our test cases compared to the BDM. This gives our MDM the potential for tackling large grids and time-dependent problems, where possibly the grid must be dynamically deformed once per time step according to the user's needs. Moreover, we elaborate on implementational aspects, in particular efficient grid searching, which is a key ingredient of the BDM. Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.apnum.2010.03.017 SN - 0168-9274 VL - 60 IS - 8 SP - 767 EP - 781 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Akimbekov, N. Sh. A1 - Zhubanova, A. A. A1 - Mansurov, Z. A. A1 - Digel, Ilya A1 - Artmann, Gerhard A1 - Temiz Artmann, Aysegül T1 - Use of Carbonized Rise Shell for the local treatment of wounds JF - Eurasian ChemTech Journal N2 - On the model of musculocutaneous wound in rats, the effect of applicative sorption by carbonized rise shell (CRS) on the healing of festering wound was studied. It has been shown, that cytological changes end with rapid scar formation. The use of CRS at the period of severe purulent wound contributes to its favorable course, prevents the development of complications of the animals from sepsis. Y1 - 2010 U6 - http://dx.doi.org/10.18321/ectj35 SN - 2522-4867 VL - 12 IS - 2 SP - 133 EP - 138 PB - Institute of Combustion Problems CY - Almaty ER - TY - JOUR A1 - Scheer, Nico A1 - Ross, Jillian A1 - Kapelyukh, Yury A1 - Rode, Anja A1 - Wolf, C. Roland T1 - In vivo responses of the human and murine pregnane X receptor to dexamethasone in mice JF - Drug Metabolism and Disposition N2 - Dexamethasone (DEX) is a potent and widely used anti-inflammatory and immunosuppressant glucocorticoid. It can bind and activate the pregnane X receptor (PXR), which plays a critical role as xenobiotic sensor in mammals to induce the expression of many enzymes, including cytochromes P450 in the CYP3A family. This induction results in its own metabolism. We have used a series of transgenic mouse lines, including a novel, improved humanized PXR line, to compare the induction profile of PXR-regulated drug-metabolizing enzymes after DEX administration, as well as looking at hepatic responses to rifampicin (RIF). The new humanized PXR model has uncovered further intriguing differences between the human and mouse receptors in that RIF only induced Cyp2b10 in the new humanized model. DEX was found to be a much more potent inducer of Cyp3a proteins in wild-type mice than in mice humanized for PXR. To assess whether PXR is involved in the detoxification of DEX in the liver, we analyzed the consequences of high doses of the glucocorticoid on hepatotoxicity on different PXR genetic backgrounds. We also studied these effects in an additional mouse model in which functional mouse Cyp3a genes have been deleted. These strains exhibited different sensitivities to DEX, indicating a protective role of the PXR and CYP3A proteins against the hepatotoxicity of this compound. Y1 - 2010 U6 - http://dx.doi.org/10.1124/dmd.109.031872 SN - 1521-009X VL - 38 IS - 7 SP - 1046 EP - 1053 PB - ASPET CY - Bethesda ER - TY - JOUR A1 - Ross, Jillian A1 - Plummer, Simon M. A1 - Rode, Anja A1 - Scheer, Nico A1 - Bower, Conrad C. A1 - Vogel, Ortwin A1 - Henderson, Colin J. A1 - Wolf, C. Roland A1 - Elcombe, Clifford R. T1 - Human constitutive androstane receptor (CAR) and pregnane X receptor (PXR) support the hypertrophic but not the hyperplastic response to the murine nongenotoxic hepatocarcinogens phenobarbital and chlordane in vivo JF - Toxicological Sciences N2 - Mouse nongenotoxic hepatocarcinogens phenobarbital (PB) and chlordane induce hepatomegaly characterized by hypertrophy and hyperplasia. Increased cell proliferation is implicated in the mechanism of tumor induction. The relevance of these tumors to human health is unclear. The xenoreceptors, constitutive androstane receptors (CARs), and pregnane X receptor (PXR) play key roles in these processes. Novel “humanized” and knockout models for both receptors were developed to investigate potential species differences in hepatomegaly. The effects of PB (80 mg/kg/4 days) and chlordane (10 mg/kg/4 days) were investigated in double humanized PXR and CAR (huPXR/huCAR), double knockout PXR and CAR (PXRKO/CARKO), and wild-type (WT) C57BL/6J mice. In WT mice, both compounds caused increased liver weight, hepatocellular hypertrophy, and cell proliferation. Both compounds caused alterations to a number of cell cycle genes consistent with induction of cell proliferation in WT mice. However, these gene expression changes did not occur in PXRKO/CARKO or huPXR/huCAR mice. Liver hypertrophy without hyperplasia was demonstrated in the huPXR/huCAR animals in response to both compounds. Induction of the CAR and PXR target genes, Cyp2b10 and Cyp3a11, was observed in both WT and huPXR/huCAR mouse lines following treatment with PB or chlordane. In the PXRKO/CARKO mice, neither liver growth nor induction of Cyp2b10 and Cyp3a11 was seen following PB or chlordane treatment, indicating that these effects are CAR/PXR dependent. These data suggest that the human receptors are able to support the chemically induced hypertrophic responses but not the hyperplastic (cell proliferation) responses. At this time, we cannot be certain that hCAR and hPXR when expressed in the mouse can function exactly as the genes do when they are expressed in human cells. However, all parameters investigated to date suggest that much of their functionality is maintained. Y1 - 2010 U6 - http://dx.doi.org/10.1093/toxsci/kfq118 SN - 1096-0929 VL - 116 IS - 2 SP - 452 EP - 466 PB - Oxford University Press CY - Oxford ER - TY - JOUR A1 - Bernecker, Andreas T1 - A European Private Company: Is Europe’s single legal form for SMEs close to approval? JF - Research Briefing N2 - This Research Briefing, issued in July 2010, concluded that: - Small and medium-sized enterprises (SMEs) in Europe have long called for a matching legal form valid across the EU (similar to that of the European company (SE) for large firms) - The main benefits would be the availability of uniform Europe-wide company structures, significant cost reductions for businesses and further integration of the internal market - Given the differing national views regarding the concrete features of the new legal form there is currently no sign of an agreement being reached at the European level in the short term; however, it is possible that progress will be made in negotiations during the year - The key issues being discussed in depth are company formation, transnationality and employee participation rights in the new European private company (SPE). Y1 - 2010 SN - 2193-5955 PB - Deutsche Bank Research CY - Frankfurt a. M. ER - TY - JOUR A1 - Horstmann, Marie-Therese A1 - Bialonski, Stephan A1 - Noenning, Nina A1 - Mai, Heinke A1 - Prusseit, Jens A1 - Wellmer, Jörg A1 - Hinrichs, Hermann A1 - Lehnertz, Klaus T1 - State dependent properties of epileptic brain networks: Comparative graph–theoretical analyses of simultaneously recorded EEG and MEG JF - Clinical Neurophysiology N2 - Objective To investigate whether functional brain networks of epilepsy patients treated with antiepileptic medication differ from networks of healthy controls even during the seizure-free interval. Methods We applied different rules to construct binary and weighted networks from EEG and MEG data recorded under a resting-state eyes-open and eyes-closed condition from 21 epilepsy patients and 23 healthy controls. The average shortest path length and the clustering coefficient served as global statistical network characteristics. Results Independent on the behavioral condition, epileptic brains exhibited a more regular functional network structure. Similarly, the eyes-closed condition was characterized by a more regular functional network structure in both groups. The amount of network reorganization due to behavioral state changes was similar in both groups. Consistent findings could be achieved for networks derived from EEG but hardly from MEG recordings, and network construction rules had a rather strong impact on our findings. Conclusions Despite the locality of the investigated processes epileptic brain networks differ in their global characteristics from non-epileptic brain networks. Further methodological developments are necessary to improve the characterization of disturbed and normal functional networks. Significance An increased regularity and a diminished modulation capability appear characteristic of epileptic brain networks. Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.clinph.2009.10.013 SN - 1388-2457 VL - 121 IS - 2 SP - 172 EP - 185 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bialonski, Stephan A1 - Horstmann, Marie-Therese A1 - Lehnertz, Klaus T1 - From brain to earth and climate systems: Small-world interaction networks or not? JF - Chaos: An Interdisciplinary Journal of Nonlinear Science N2 - We consider recent reports on small-world topologies of interaction networks derived from the dynamics of spatially extended systems that are investigated in diverse scientific fields such as neurosciences, geophysics, or meteorology. With numerical simulations that mimic typical experimental situations, we have identified an important constraint when characterizing such networks: indications of a small-world topology can be expected solely due to the spatial sampling of the system along with the commonly used time series analysis based approaches to network characterization. Y1 - 2010 U6 - http://dx.doi.org/10.1063/1.3360561 SN - 1089-7682 VL - 20 IS - 1 PB - AIP Publishing CY - Melville, NY ER - TY - JOUR A1 - Barbazán, Paula A1 - Hagenbach, Adelheid A1 - Paulßen, Elisabeth A1 - Abram, Ulrich A1 - Carballo, Rosa A1 - Rodriguez-Hermida, Sabina A1 - Vázquez-López, Ezequiel M. T1 - Tricarbonyl Rhenium(I) and Technetium(I) Complexes with Hydrazones Derived from 4,5-Diazafluoren-9-one and 1,10-Phenanthroline-5,6-dione JF - European Journal of Inorganic Chemistry N2 - Tricarbonylrhenium(I) and -technetium(I) halide (halide = Cl and Br) complexes of ligands derived from 4,5-diazafluoren-9-one (df) and 1,10-phenanthroline-5,6-dione (phen) derivatives of benzoic and 2-hydroxybenzoic acid hydrazides have been prepared. The complexes have been characterized by elemental analysis, MS, IR, 1H NMR and absorption and emission UV/Vis spectroscopic methods. The metal centres (ReI and TcI) are coordinated through the nitrogen imine atoms and establish five-membered chelate rings, whereas the hydrazone groups stand uncoordinated. The 1H NMR spectra suggest the same behaviour in solution on the basis of only marginal variations in the chemical shifts of the hydrazine protons. Y1 - 2010 U6 - http://dx.doi.org/10.1002/ejic.201000522 SN - 1099-0682 IS - 29 SP - 4622 EP - 4630 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Paulßen, Elisabeth A1 - Alberto, Roger A1 - Abram, Ulrich T1 - Synthesis, Characterization, and Structures of R3EOTcO3 Complexes (E = C, Si, Ge, Sn, Pb) and Related Compounds JF - Inorganic Chemistry N2 - AgTcO4 reacts with R3ECl compounds (E = C, Si, Ge, Sn, Pb; R = Me, iPr, tBu, Ph), tBu2SnCl2, or PhMgCl under formation of novel trioxotechnetium(VII) derivatives. The carbon and silicon derivatives readily undergo decomposition, which was proven by 99Tc NMR spectroscopy and the isolation of decomposition products such as [TcOCl3(THF)(OH2)]. Compounds [Ph3GeOTcO3], [(THF)Ph3SnOTcO3], [(O3TcO)SntBu2(OH)]2, and [(THF)4Mg(OTcO3)2] are more stable and were isolated in crystalline form and characterized by X-ray diffraction. Y1 - 2010 U6 - http://dx.doi.org/10.1021/ic1001094 SN - 1520-510X VL - 49 IS - 7 SP - 3525 EP - 3530 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Paulßen, Elisabeth A1 - Schweighöfer, Philip V. A1 - Abram, Ulrich T1 - Reactions of [ReOX3(PPh3)2] Complexes (X = Cl, Br) with Phenylacetylene and the Structures of the Products JF - Zeitschrift für anorganische und allgemeine Chemie : ZAAC = Journal of inorganic and general chemistry N2 - Oxorhenium(V) complexes [ReOX3(PPh3)2] (X = Cl, Br) react with phenylacetylene under formation of complexes with ylide-type ligands. Compounds of the compositions [ReOCl3(PPh3){C(Ph)C(H)(PPh3)}] (1), [ReOBr3(OPPh3){C(Ph)C(H)(PPh3)}] (2), and [ReOBr3(OPPh3){C(H)C(Ph)(PPh3)}] (3) were isolated and characterized by X-ray diffraction. They contain a ligand, which was formed by a nucleophilic attack of released PPh3 at coordinated phenylacetylene. The structures of the products show that there is no preferable position for this attack. Cleavage of the Re–C bond in 3 and dimerization of the organic ligand resulted in the formation of the [{(PPh3)(H)CC(Ph)}2]2+ cation, which crystallized as its [(ReOBr4)(OReO3)]2– salt. Y1 - 2010 U6 - http://dx.doi.org/10.1002/zaac.200900478 SN - 1521-3749 VL - 636 IS - 5 SP - 779 EP - 783 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tippkötter, Nils A1 - Roikaew, Wipa A1 - Ulber, Roland A1 - Hoffmann, Alexander A1 - Denzler, Hans-Jörg A1 - Buchholz, Heinrich T1 - Paracoccus denitrificans for the effluent recycling during continuous denitrification of liquid food JF - Biotechnology Progress N2 - Nitrate is an undesirable component of several foods. A typical case of contamination with high nitrate contents is whey concentrate, containing nitrate in concentrations up to 25 l. The microbiological removal of nitrate by Paracoccus denitrificans under formation of harmless nitrogen in combination with a cell retention reactor is described here. Focus lies on the resource-conserving design of a microbal denitrification process. Two methods are compared. The application of polyvinyl alcohol-immobilized cells, which can be applied several times in whey feed, is compared with the implementation of a two step denitrification system. First, the whey concentrate's nitrate is removed by ion exchange and subsequently the eluent regenerated by microorganisms under their retention by crossflow filtration. Nitrite and nitrate concentrations were determined by reflectometric color measurement with a commercially available Reflectoquant® device. Correction factors for these media had to be determined. During the pilot development, bioreactors from 4 to 250 mg·L-1 and crossflow units with membrane areas from 0.02 to 0.80 m2 were examined. Based on the results of the pilot plants, a scaling for the exemplary process of denitrifying 1,000 tons per day is discussed. Y1 - 2010 U6 - http://dx.doi.org/10.1002/btpr.384 SN - 8756-7938 VL - 26 IS - 3 SP - 756 EP - 762 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Schlamann, Marc A1 - Yoon, Min-Suk A1 - Maderwald, Stefan A1 - Pietrzyk, Thomas A1 - Bitz, Andreas A1 - Gerwig, Marcus A1 - Forsting, Michael A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Kastrup, Oliver T1 - Short term effects of magnetic resonance imaging on excitability of the motor cortex at 1.5T and 7T JF - Academic Radiology N2 - Rationale and Objectives The increasing spread of high-field and ultra-high-field magnetic resonance imaging (MRI) scanners has encouraged new discussion of the safety aspects of MRI. Few studies have been published on possible cognitive effects of MRI examinations. The aim of this study was to examine whether changes are measurable after MRI examinations at 1.5 and 7 T by means of transcranial magnetic stimulation (TMS). Materials and Methods TMS was performed in 12 healthy, right-handed male volunteers. First the individual motor threshold was specified, and then the cortical silent period (SP) was measured. Subsequently, the volunteers were exposed to the 1.5-T MRI scanner for 63 minutes using standard sequences. The MRI examination was immediately followed by another TMS session. Fifteen minutes later, TMS was repeated. Four weeks later, the complete setting was repeated using a 7-T scanner. Control conditions included lying in the 1.5-T scanner for 63 minutes without scanning and lying in a separate room for 63 minutes. TMS was performed in the same way in each case. For statistical analysis, Wilcoxon's rank test was performed. Results Immediately after MRI exposure, the SP was highly significantly prolonged in all 12 subjects at 1.5 and 7 T. The motor threshold was significantly increased. Fifteen minutes after the examination, the measured value tended toward normal again. Control conditions revealed no significant differences. Conclusion MRI examinations lead to a transient and highly significant alteration in cortical excitability. This effect does not seem to depend on the strength of the static magnetic field. Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.acra.2009.10.004 SN - 1076-6332 VL - 17 IS - 3 SP - 277 EP - 281 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schlamann, Marc A1 - Voigt, Melanie A. A1 - Maderwald, Stefan A1 - Bitz, Andreas A1 - Kraff, Oliver A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Forsting, Michael A1 - Wilhelm, Hans T1 - Exposure to high-field MRI does not affect cognitive function JF - Journal of Magnetic Resonance Imaging N2 - Purpose To assess potential cognitive deficits under the influence of static magnetic fields at various field strengths some studies already exist. These studies were not focused on attention as the most vulnerable cognitive function. Additionally, mostly no magnetic resonance imaging (MRI) sequences were performed. Materials and Methods In all, 25 right-handed men were enrolled in this study. All subjects underwent one MRI examination of 63 minutes at 1.5 T and one at 7 T within an interval of 10 to 30 days. The order of the examinations was randomized. Subjects were referred to six standardized neuropsychological tests strictly focused on attention immediately before and after each MRI examination. Differences in neuropsychological variables between the timepoints before and after each MRI examination were assessed and P-values were calculated Results Only six subtests revealed significant differences between pre- and post-MRI. In these tests the subjects achieved better results in post-MRI testing than in pre-MRI testing (P = 0.013–0.032). The other tests revealed no significant results. Conclusion The improvement in post-MRI testing is only explicable as a result of learning effects. MRI examinations, even in ultrahigh-field scanners, do not seem to have any persisting influence on the attention networks of human cognition immediately after exposure. Y1 - 2010 U6 - http://dx.doi.org/10.1002/jmri.22065 SN - 1522-2586 VL - 31 IS - 5 SP - 1061 EP - 1066 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - Kraff, Oliver A1 - Bitz, Andreas A1 - Dammann, Philipp A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - An eight-channel transmit/receive multipurpose coil for musculoskeletal MR imaging at 7 T JF - Medical Physics N2 - Purpose: MRI plays a leading diagnostic role in assessing the musculoskeletal (MSK) system and is well established for most questions at clinically used field strengths (up to 3 T). However, there are still limitations in imaging early stages of cartilage degeneration, very fine tendons and ligaments, or in locating nerve lesions, for example. 7 T MRI of the knee has already received increasing attention in the current published literature, but there is a strong need to develop new radiofrequency (RF) coils to assess more regions of the MSK system. In this work, an eight-channel transmit/receive RF array was built as a multipurpose coil for imaging some of the thus far neglected regions. An extensive coil characterization protocol and first in vivo results of the human wrist, shoulder, elbow, knee, and ankle imaged at 7 T will be presented. Methods: Eight surface loop coils with a dimension ofurn:x-wiley:00942405:media:mp7176:mp7176-math-0001 were machined from FR4 circuit board material. To facilitate easy positioning, two coil clusters, each with four loop elements, were combined to one RF transmit/receive array. An overlapped and shifted arrangement of the coil elements was chosen to reduce the mutual inductance between neighboring coils. A phantom made of body-simulating liquid was used for tuning and matching on the bench. Afterward, the S-parameters were verified on a human wrist, elbow, and shoulder. For safety validation, a detailed compliance test was performed including full wave simulations of the RF field distribution and the corresponding specific absorption rate (SAR) for all joints. In vivo images of four volunteers were assessed with gradient echo and spin echo sequences modified to obtain optimal image contrast, full anatomic coverage, and the highest spatial resolution within a reasonable acquisition time. The performance of the RF coil was additionally evaluated by in vivo B1 mapping. Results: A comparison of B1 per unit power, flip angle distribution, and anatomic images showed a fairly homogeneous excitation for the smaller joints (elbow, wrist, and ankle), while for the larger joints, the shoulder and especially the knee, B1 inhomogeneities and limited penetration depth were more pronounced. However, the greater part of the shoulder joint could be imaged.In vivo images rendered very fine anatomic details such as fascicles of the median nerve and the branching of the nerve bundles. High-resolution images of cartilage, labrum, and tendons could be acquired. Additionally, turbo spin echo (TSE) and inversion recovery sequences performed very well. Conclusions: This study demonstrates that the concept of two four-channel transmit/receive RF arrays can be used as a multipurpose coil for high-resolutionin vivo MR imaging of the musculoskeletal system at 7 T. Not only gradient echo but also typical clinical and SAR-intensive sequences such as STIR and TSE performed well. Imaging of small structures and peripheral nerves could in particular benefit from this technique. Y1 - 2010 U6 - http://dx.doi.org/10.1118/1.3517176 SN - 2473-4209 VL - 37 IS - 12 SP - 6368 EP - 6376 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Orzada, Stephan A1 - Maderwald, Stefan A1 - Poser, Benedikt Andreas A1 - Bitz, Andreas A1 - Quick, Harald H. A1 - Ladd, Mark E. T1 - RF excitation using time interleaved acquisition of modes (TIAMO) to address B1 inhomogeneity in high-field MRI JF - Magnetic Resonance in Medicine N2 - As the field strength and, therefore, the operational frequency in MRI is increased, the wavelength approaches the size of the human head/body, resulting in wave effects, which cause signal decreases and dropouts. Several multichannel approaches have been proposed to try to tackle these problems, including RF shimming, where each element in an array is driven by its own amplifier and modulated with a certain (constant) amplitude and phase relative to the other elements, and Transmit SENSE, where spatially tailored RF pulses are used. In this article, a relatively inexpensive and easy to use imaging scheme for 7 Tesla imaging is proposed to mitigate signal voids due to B1 field inhomogeneity. Two time-interleaved images are acquired using a different excitation mode for each. By forming virtual receive elements, both images are reconstructed together using GRAPPA to achieve a more homogeneous image, with only small SNR and SAR penalty in head and body imaging at 7 Tesla. Y1 - 2010 U6 - http://dx.doi.org/10.1002/mrm.22527 SN - 1522-2594 VL - 64 IS - 2 SP - 327 EP - 333 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - Aggeloussis, Nickos A1 - Giannakou, Erasmia A1 - Albracht, Kirsten A1 - Arampatzis, Adamantios T1 - Reproducibility of fascicle length and pennation angle of gastrocnemius medialis in human gait in vivo JF - Gait and Posture N2 - The purpose of the current study was to examine the reproducibility of fascicle length and pennation angle of gastrocnemius medialis while human walking. To the best of our knowledge, this is the first study of the reproducibility of fascicle length and pennation angle of gastrocnemius medialis in vivo during human gait. Twelve males performed 10 gait trials on a treadmill, in 2 separate days. B-mode ultrasonography, with the ultrasound probe firmly adjusted in the transverse and frontal planes using a special cast, was used to measure the fascicle length and the pennation angle of the gastrocnemius medialis (GM). A Vicon 624 system with three cameras operating at 120 Hz was also used to record the ankle and knee joint angles. The results showed that measurements of fascicle length and pennation angle showed high reproducibility during the gait cycle, both within the same day and between different days. Moreover, the root mean square differences between the repeated waveforms of both variables were very small, compared with their ranges (fascicle length: RMS = ∼3 mm, range: 38–63 mm; pennation angle: RMS = ∼1.5°, range: 22–32°). However, their reproducibility was lower compared to the joint angles. It was found that representative data have to be derived by a wide number of gait trials (fascicle length ∼six trials, pennation angle more than 10 trials), to assure the reliability of the fascicle length and pennation angle in human gait. Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.gaitpost.2009.08.249 SN - 0966-6362 VL - 31 IS - 1 SP - 73 EP - 77 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Arampatzis, Adamantios A1 - Peper, Andreas A1 - Bierbaum, Stefanie A1 - Albracht, Kirsten T1 - Plasticity of human Achilles tendon mechanical and morphological properties in response to cyclic strain JF - Journal of Biomechanics N2 - The purpose of the current study in combination with our previous published data (Arampatzis et al., 2007) was to examine the effects of a controlled modulation of strain magnitude and strain frequency applied to the Achilles tendon on the plasticity of tendon mechanical and morphological properties. Eleven male adults (23.9±2.2 yr) participated in the study. The participants exercised one leg at low magnitude tendon strain (2.97±0.47%), and the other leg at high tendon strain magnitude (4.72±1.08%) of similar frequency (0.5 Hz, 1 s loading, 1 s relaxation) and exercise volume (integral of the plantar flexion moment over time) for 14 weeks, 4 days per week, 5 sets per session. The exercise volume was similar to the intervention of our earlier study (0.17 Hz frequency; 3 s loading, 3 s relaxation) allowing a direct comparison of the results. Before and after the intervention ankle joint moment has been measured by a dynamometer, tendon–aponeurosis elongation by ultrasound and cross-sectional area of the Achilles tendon by magnet resonance images (MRI). We found a decrease in strain at a given tendon force, an increase in tendon–aponeurosis stiffness and tendon elastic modulus of the Achilles tendon only in the leg exercised at high strain magnitude. The cross-sectional area (CSA) of the Achilles tendon did not show any statistically significant (P>0.05) differences to the pre-exercise values in both legs. The results indicate a superior improvement in tendon properties (stiffness, elastic modulus and CSA) at the low frequency (0.17 Hz) compared to the high strain frequency (0.5 Hz) protocol. These findings provide evidence that the strain magnitude applied to the Achilles tendon should exceed the value, which occurs during habitual activities to trigger adaptational effects and that higher tendon strain duration per contraction leads to superior tendon adaptational responses. Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.jbiomech.2010.08.014 SN - 0021-9290 VL - 43 IS - 16 SP - 3073 EP - 3079 PB - Elsevier CY - Amsterdam ER -