TY  - CHAP
A1  - Schwarte, Rudolf
A1  - Heinol, Horst-Guenther
A1  - Buxbaum, Bernd
A1  - Ringbeck, Thorsten
A1  - Xu, Z.
A1  - Hartmann, K.
ED  - Jähne, Bernd
T1  - Principles of three-dimensional imaging techniques
T2  - Sensors and imaging. - (Handbook of computer vision and applications ; Vol. 1)
Y1  - 1999
SN  - 0-12-379771-3 (Einzelbd.)
SN  - 0-12-379770-5 (Gesamtwerk)
SP  - 463
EP  - 485
PB  - Academic Press
CY  - San Diego
ER  - 
TY  - JOUR
A1  - Windmüller, Anna
A1  - Schaps, Kristian
A1  - Zantis, Frederik
A1  - Domgans, Anna
A1  - Taklu, Bereket Woldegbreal
A1  - Yang, Tingting
A1  - Tsai, Chih-Long
A1  - Schierholz, Roland
A1  - Yu, Shicheng
A1  - Kungl, Hans
A1  - Tempel, Hermann
A1  - Dunin-Borkowski, Rafal E.
A1  - Hüning, Felix
A1  - Hwang, Bing Joe
A1  - Eichel, Rüdiger-A.
T1  - Electrochemical activation of LiGaO2: implications for ga-doped garnet solid electrolytes in li-metal batteries
JF  - ACS Applied Materials & Interfaces
N2  - Ga-doped Li7La3Zr2O12 garnet solid electrolytes exhibit the highest Li-ion conductivities among the oxide-type garnet-structured solid electrolytes, but instabilities toward Li metal hamper their practical application. The instabilities have been assigned to direct chemical reactions between LiGaO2 coexisting phases and Li metal by several groups previously. Yet, the understanding of the role of LiGaO2 in the electrochemical cell and its electrochemical properties is still lacking. Here, we are investigating the electrochemical properties of LiGaO2 through electrochemical tests in galvanostatic cells versus Li metal and complementary ex situ studies via confocal Raman microscopy, quantitative phase analysis based on powder X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electron energy loss spectroscopy. The results demonstrate considerable and surprising electrochemical activity, with high reversibility. A three-stage reaction mechanism is derived, including reversible electrochemical reactions that lead to the formation of highly electronically conducting products. The results have considerable implications for the use of Ga-doped Li7La3Zr2O12 electrolytes in all-solid-state Li-metal battery applications and raise the need for advanced materials engineering to realize Ga-doped Li7La3Zr2O12for practical use.
KW  - LiGaO2
KW  - garnet solid electrolyte
KW  - ga-doping
KW  - Li7La3Zr2O12
KW  - solid-state battery
Y1  - 2024
U6  - https://doi.org/10.1021/acsami.4c03729
SN  - 39181–3919
VL  - 16
IS  - 30
PB  - ACS Publications
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Gräßl, Andreas
A1  - Renz, Wolfgang
A1  - Hezel, Fabian
A1  - Dieringer, Matthias A.
A1  - Winter, Lukas
A1  - Özerdem, Celal
A1  - Rieger, Jan
A1  - Kellmann, Peter
A1  - Santoro, Davide
A1  - Lindel, Tomasz Dawid
A1  - Frauenrath, Tobias
A1  - Pfeiffer, Harald
A1  - Niendorf, Thoralf
T1  - Modular 32-channel transceiver coil array for cardiac MRI at 7.0T
JF  - Magnetic Resonance in Medicine
N2  - Purpose
To design and evaluate a modular transceiver coil array with 32 independent channels for cardiac MRI at 7.0T.

Methods
The modular coil array comprises eight independent building blocks, each containing four transceiver loop elements. Numerical simulations were used for B1+ field homogenization and radiofrequency (RF) safety validation. RF characteristics were examined in a phantom study. The array's suitability for accelerated high spatial resolution two-dimensional (2D) FLASH CINE imaging of the heart was examined in a volunteer study.

Results
Transmission field adjustments and RF characteristics were found to be suitable for the volunteer study. The signal-to-noise intrinsic to 7.0T together with the coil performance afforded a spatial resolution of 1.1 × 1.1 × 2.5 mm3 for 2D CINE FLASH MRI, which is by a factor of 6 superior to standardized CINE protocols used in clinical practice at 1.5T. The 32-channel transceiver array supports one-dimensional acceleration factors of up to R = 4 without impairing image quality significantly.

Conclusion
The modular 32-channel transceiver cardiac array supports accelerated and high spatial resolution cardiac MRI. The array is compatible with multichannel transmission and provides a technological basis for future clinical assessment of parallel transmission techniques at 7.0T.
Y1  - 2013
U6  - https://doi.org/10.1002/mrm.24903
SN  - 1522-2594
VL  - 72
IS  - 1
SP  - 276
EP  - 290
PB  - Wiley-Liss
CY  - New York
ER  - 
TY  - JOUR
A1  - Orzada, Stephan
A1  - Fiedler, Thomas M.
A1  - Bitz, Andreas
A1  - Ladd, Mark E.
A1  - Quick, Harald H.
T1  - Local SAR compression with overestimation control to reduce maximum relative SAR overestimation and improve multi-channel RF array performance
JF  - Magnetic Resonance Materials in Physics, Biology and Medicine
N2  - Objective
In local SAR compression algorithms, the overestimation is generally not linearly dependent on actual local SAR. This can lead to large relative overestimation at low actual SAR values, unnecessarily constraining transmit array performance.

Method
Two strategies are proposed to reduce maximum relative overestimation for a given number of VOPs. The first strategy uses an overestimation matrix that roughly approximates actual local SAR; the second strategy uses a small set of pre-calculated VOPs as the overestimation term for the compression.

Result
Comparison with a previous method shows that for a given maximum relative overestimation the number of VOPs can be reduced by around 20% at the cost of a higher absolute overestimation at high actual local SAR values.

Conclusion
The proposed strategies outperform a previously published strategy and can improve the SAR compression where maximum relative overestimation constrains the performance of parallel transmission.
Y1  - 2020
SN  - 1352-8661
U6  - https://doi.org/10.1007/s10334-020-00890-0
IS  - 34 (2021)
SP  - 153
EP  - 164
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Fiedler, Thomas M.
A1  - Ladd, Mark E.
A1  - Bitz, Andreas
T1  - SAR Simulations & Safety
JF  - NeuroImage
Y1  - 2017
U6  - https://doi.org/10.1016/j.neuroimage.2017.03.035
SN  - 1053-8119
IS  - Epub ahead of print
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Orzada, Stephan
A1  - Solbach, Klaus
A1  - Gratz, Marcel
A1  - Brunheim, Sascha
A1  - Fiedler, Thomas M.
A1  - Johst, Sören
A1  - Bitz, Andreas
A1  - Shooshtary, Samaneh
A1  - Abuelhaija, Ashraf
A1  - Voelker, Maximilian N.
A1  - Rietsch, Stefan H. G.
A1  - Kraff, Oliver
A1  - Maderwald, Stefan
A1  - Flöser, Martina
A1  - Oehmingen, Mark
A1  - Quick, Harald H.
A1  - Ladd, Mark E.
T1  - A 32-channel parallel transmit system add-on for 7T MRI
JF  - Plos one
Y1  - 2019
U6  - https://doi.org/10.1371/journal.pone.0222452
ER  - 
TY  - JOUR
A1  - Orzada, Stephan
A1  - Bitz, Andreas
A1  - Johst, Sören
A1  - Gratz, Marcel
A1  - Völker, Maximilian N.
A1  - Kraff, Oliver
A1  - Abuelhaija, Ashraf
A1  - Fiedler, Thomas M.
A1  - Solbach, Klaus
A1  - Quick, Harald H.
A1  - Ladd, Mark E.
T1  - Analysis of an integrated 8-Channel Tx/Rx body array for use as a body coil in 7-Tesla MRI
JF  - Frontiers in Physics
Y1  - 2017
U6  - https://doi.org/10.3389/fphy.2017.00017
SN  - 2296-424X
N1  - Article number 17
VL  - 5
IS  - Jun
ER  - 
TY  - JOUR
A1  - Scholl, Ingrid
A1  - Palm, Christoph
A1  - Lehmann, Thomas Martin
A1  - Spitzer, Klaus
T1  - Quantitative Farbmessung in laryngoskopischen Bildern. Palm, C; Scholl, I; Lehmann, TM; Spitzer, K.
JF  - Bildverarbeitung für die Medizin 1998. Hrsg.: Thomas Lehmann ...
Y1  - 1998
SN  - 3-540-63885-7
SP  - 412
EP  - 416
PB  - Springer
CY  - Berlin
ER  - 
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  -