TY - JOUR A1 - Fiedler, Thomas M. A1 - Ladd, Mark E. A1 - Bitz, Andreas T1 - RF safety assessment of a bilateral four-channel transmit/receive 7 Tesla breast coil: SAR versus temperature limits JF - Medical Physics Y1 - 2017 U6 - https://doi.org/10.1002/mp.12034 N1 - This article is corrected by: Errata: Erratum: “RF safety assessment of a bilateral four-channel transmit/receive 7 Tesla breast coil: SAR versus tissue temperature limits” [Med. Phys. 44(1), 143–157 (2017)] Volume 44, Issue 2, 772 VL - 44 IS - 1 SP - 143 EP - 157 ER - TY - JOUR A1 - Dieringer, Matthias A. A1 - Renz, Wolfgang A1 - Lindel, Tomasz Dawid A1 - Seifert, Frank A1 - Frauenrath, Tobias A1 - von Knobelsdorf-Brenkenhoff, Florian A1 - Waiczies, Helmar A1 - Hoffmann, Werner A1 - Rieger, Jan A1 - Pfeiffer, Harald A1 - Ittermann, Bernd A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf T1 - Design and application of a four-channel transmit/receive surface coil for functional cardiac imaging at 7T JF - Journal of Magnetic Resonance Imaging N2 - Purpose To design and evaluate a four-channel cardiac transceiver coil array for functional cardiac imaging at 7T. Materials and Methods A four-element cardiac transceiver surface coil array was developed with two rectangular loops mounted on an anterior former and two rectangular loops on a posterior former. specific absorption rate (SAR) simulations were performed and a Burn:x-wiley:10531807:media:JMRI22451:tex2gif-stack-1 calibration method was applied prior to obtain 2D FLASH CINE (mSENSE, R = 2) images from nine healthy volunteers with a spatial resolution of up to 1 × 1 × 2.5 mm3. Results Tuning and matching was found to be better than 10 dB for all subjects. The decoupling (S21) was measured to be >18 dB between neighboring loops, >20 dB for opposite loops, and >30 dB for other loop combinations. SAR values were well within the limits provided by the IEC. Imaging provided clinically acceptable signal homogeneity with an excellent blood-myocardium contrast applying the Burn:x-wiley:10531807:media:JMRI22451:tex2gif-stack-2 calibration approach. Conclusion A four-channel cardiac transceiver coil array for 7T was built, allowing for cardiac imaging with clinically acceptable signal homogeneity and an excellent blood-myocardium contrast. Minor anatomic structures, such as pericardium, mitral, and tricuspid valves and their apparatus, as well as trabeculae, were accurately delineated. Y1 - 2011 U6 - https://doi.org/10.1002/jmri.22451 SN - 1522-2586 VL - 33 IS - 3 SP - 736 EP - 741 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - Fiedler, Thomas M. A1 - Ladd, Mark E. A1 - Clemens, Markus A1 - Bitz, Andreas T1 - Safety of subjects during radiofrequency exposure in ultra-high-field magnetic resonance imaging JF - IEEE Letters on Electromagnetic Compatibility Practice and Applications N2 - Magnetic resonance imaging (MRI) is one of the most important medical imaging techniques. Since the introduction of MRI in the mid-1980s, there has been a continuous trend toward higher static magnetic fields to obtain i.a. a higher signal-to-noise ratio. The step toward ultra-high-field (UHF) MRI at 7 Tesla and higher, however, creates several challenges regarding the homogeneity of the spin excitation RF transmit field and the RF exposure of the subject. In UHF MRI systems, the wavelength of the RF field is in the range of the diameter of the human body, which can result in inhomogeneous spin excitation and local SAR hotspots. To optimize the homogeneity in a region of interest, UHF MRI systems use parallel transmit systems with multiple transmit antennas and time-dependent modulation of the RF signal in the individual transmit channels. Furthermore, SAR increases with increasing field strength, while the SAR limits remain unchanged. Two different approaches to generate the RF transmit field in UHF systems using antenna arrays close and remote to the body are investigated in this letter. Achievable imaging performance is evaluated compared to typical clinical RF transmit systems at lower field strength. The evaluation has been performed under consideration of RF exposure based on local SAR and tissue temperature. Furthermore, results for thermal dose as an alternative RF exposure metric are presented. Y1 - 2020 SN - 2637-6423 U6 - https://doi.org/10.1109/LEMCPA.2020.3029747 VL - 2 IS - 3 SP - 1 EP - 8 PB - IEEE CY - New York, NY ER - TY - BOOK A1 - Scholl, Ingrid ED - Lehmann, Thomas Martin ED - Spitzer, Klaus T1 - Bildverarbeitung für die Medizin : Algorithmen - Systeme - Anwendungen ; proceedings des Aachener Workshops am 8. und 9. November 1996 / Institut für Medizinische Informatik und Biometrie der RWTH Aachen. Hrsg. von Thomas Lehmann ; Ingrid Scholl ; Klaus Spitzer Y1 - 1996 SN - 3-86073-519-5 PB - Verlag der Augustinus-Buchhandlung CY - Aachen ER - TY - CHAP A1 - Lindenlauf, Simon A1 - Höfken, Hans-Wilhelm A1 - Schuba, Marko T1 - Cold Boot Attacks on DDR2 and DDR3 SDRAM T2 - 10th International Conference on Availability, Reliability and Security (ARES) 2015 Y1 - 2015 U6 - https://doi.org/10.1109/ARES.2015.28 SP - 287 EP - 292 ER -