TY - JOUR A1 - Kraff, Oliver A1 - Bitz, Andreas A1 - Breyer, Tobias A1 - Kruszona, Stefan A1 - Maderwald, Stefan A1 - Brote, Irina A1 - Gizewski, Elke R. A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - A transmit/receive radiofrequency array for imaging the carotid arteries at 7 Tesla: coil design and first in vivo results JF - Investigative Radiology N2 - Objective: To develop a transmit/receive radiofrequency (RF) array for magnetic resonance imaging (MRI) of the carotid arteries at 7 T. The prototype is characterized in numerical simulations and bench measurements, and the feasibility of plaque imaging at 7 T is demonstrated in first in vivo images. Materials and Methods: The RF phased array coil consists of 8 surface loop coils. To allow imaging of both sides of the neck, the RF array is divided into 2 coil clusters, each with 4 overlapping loop elements. For safety validation, numerical computations of the RF field distribution and the corresponding specific absorption rate were performed on the basis of a heterogeneous human body model. To validate the coil model, maps of the transmit B1+ field were compared between simulation and measurement. In vivo images of a healthy volunteer and a patient (ulcerating plaque and a 50% stenosis of the right internal carotid artery) were acquired using a 3-dimensional FLASH sequence with a high isotropic spatial resolution of 0.54 mm as well as using pulse-triggered proton density (PD)/T2-weighted turbo spin echo sequences. Results: Measurements of the S-parameters yielded a reflection and isolation of the coil elements of better than −18 and −13 dB, respectively. Measurements of the g-factor indicated good image quality for parallel imaging acceleration factors up to 2.4. A similar distribution and a very good match of the absolute values were found between the measured and simulated B1+ transmit RF field for the validation of the coil model. In vivo images revealed good signal excitation of both sides of the neck and a high vessel-to-background image contrast for the noncontrast-enhanced 3-dimensional FLASH sequence. Imaging at 7 T could depict the extent of stenosis, and revealed the disruption and ulcer of the plaque. Conclusions: This study demonstrates that 2 four-channel transmit/receive RF arrays for each side of the neck is a suitable concept for in vivo MRI of the carotid arteries at 7 Tesla. Further studies are needed to explore and exploit the full potential of 7 T high-field MRI for carotid atherosclerotic plaque imaging. Y1 - 2011 U6 - http://dx.doi.org/10.1097/RLI.0b013e318206cee4 SN - 1536-0210 VL - 46 IS - 4 SP - 246 EP - 254 PB - Wolters Kluwer CY - Köln ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Lanzl, Ines M. A1 - Schmidt-Trucksäss, A. A1 - Sitnikova, Diana A1 - Ali, Mohammad A1 - Blume, Katharina A1 - Halle, Martin A1 - Hansser, Henner T1 - Dynamic retinal vessel response to flicker in obesity: A methodological approach JF - Microvascular Research Y1 - 2011 SN - 0026-2862 VL - 81 IS - 1 SP - 123 EP - 128 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Lanzl, Ines M. T1 - Can vascular function be assessed by the interpretation of retinal vascular diameter changes? JF - Investigative Ophthalmology & Visual Science, IOVS. 52 (2011), H. 1 Y1 - 2011 SN - 0146-0404 SP - 635 EP - 636 PB - ARVO CY - Rockville, Md. ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Baumann, Marcus A1 - Vilser, Walthard A1 - Lanzl, Ines M. T1 - Pulse wave velocity in retinal arteries of healthy volunteers JF - British Journal of Ophthalmology (eBJO) Y1 - 2011 SN - 1468-2079 VL - 95 IS - 11 SP - 675 EP - 679 PB - BMJ Publ. Group CY - London ER - TY - JOUR A1 - Kleefeld, A. A1 - Reißel, Martin T1 - The Levenberg–Marquardt method applied to a parameter estimation problem arising from electrical resistivity tomography JF - Applied Mathematics and Computation Y1 - 2011 SN - 0096-3003 VL - 217 IS - 9 SP - 4490 EP - 4501 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Friedrich, Peter A1 - Berger, Jörg A1 - Suso, Henri-Pierre A1 - Kupyna, Andriy A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Optimisation and fabrication of a calorimetric gas sensor built up on a polyimide substrate for H2O2 monitoring JF - Physica status solidi (a) : applications and material science. 208 (2011), H. 6 Y1 - 2011 SN - 1862-6319 SP - 1235 EP - 1240 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Kirchner, Patrick A1 - Li, Bin A1 - Spelthahn, Heiko A1 - Henkel, Hartmut A1 - Schneider, Andreas A1 - Friedrich, Peter A1 - Kolstad, Jens A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Thin-film calorimetric H2O2 gas sensor for the validation of germicidal effectivity in aseptic filling processes JF - Sensors and Actuators B: Chemical. 154 (2011), H. 2 Y1 - 2011 SN - 1873-3077 N1 - EUROSENSORS XXIII SP - 257 EP - 263 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kern, Alexander A1 - Schelthoff, Christof A1 - Mathieu, Moritz T1 - Calculation of interception efficiencies for airterminations using a dynamic electro-geometrical model Y1 - 2011 N1 - XI International Symposium on Lightning Protection (SIPDA), Fortaleza (Brasilien), 2011. SP - 1 EP - 6 PB - IEEE CY - New York ER - TY - JOUR A1 - Kern, Alexander A1 - Schelthoff, Christof A1 - Mathieu, Moritz T1 - Probability of lightning strikes to air-terminations of structures using the electro-geometrical model theory and the statistics of lightning current parameters JF - Atmospheric Research. 104 (2011) Y1 - 2011 SN - 0169-8095 N1 - Article in Press PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Karamanidis, Kiros A1 - Albracht, Kirsten A1 - Braunstein, Bjoern A1 - Catala, Maria Moreno A1 - Goldmann, Jan-Peter A1 - Brüggemann, Gert-Peter T1 - Lower leg musculoskeletal geometry and sprint performance JF - Gait and Posture N2 - The purpose of this study was to investigate whether sprint performance is related to lower leg musculoskeletal geometry within a homogeneous group of highly trained 100-m sprinters. Using a cluster analysis, eighteen male sprinters were divided into two groups based on their personal best (fast: N = 11, 10.30 ± 0.07 s; slow: N = 7, 10.70 ± 0.08 s). Calf muscular fascicle arrangement and Achilles tendon moment arms (calculated by the gradient of tendon excursion versus ankle joint angle) were analyzed for each athlete using ultrasonography. Achilles tendon moment arm, foot and ankle skeletal geometry, fascicle arrangement as well as the ratio of fascicle length to Achilles tendon moment arm showed no significant (p > 0.05) correlation with sprint performance, nor were there any differences in the analyzed musculoskeletal parameters between the fast and slow sprinter group. Our findings provide evidence that differences in sprint ability in world-class athletes are not a result of differences in the geometrical design of the lower leg even when considering both skeletal and muscular components. Y1 - 2011 U6 - http://dx.doi.org/10.1016/j.gaitpost.2011.03.009 SN - 0966-6362 VL - 34 IS - 1 SP - 138 EP - 141 PB - Elsevier CY - Amsterdam ER -