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Protocol of the 3rd MR-EM-Simulation Meeting in Essen, 2012

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Protocol of the 3rd MR-EM-Simulation Meeting in Essen, 2012

PostMon 17. Dec 2012, 04:26

Protocol of MR-EM Simulation Meeting 2012

• Welcome to the audience by Andreas Bitz and Tim Herrmann
• Oral work in progress talks followed by fruitful discussion
o Jens Hoffmann (MPI for Biological Cybernetics, Tübingen) - Simulation of a Dual-Row Transmit Array for 9.4 T Neuroimaging
• The Dual-Row Transmit Array show a higher SAR transmit efficiency
• The high number of the used capacitors (equivalent series resistance of the ATC NM Caps 0,3 Ohm @ 400 MHz) take 40% losses
Related publications:
• “A 16-Element Dual-row Transmit Coil Array for 3D RF Shimming at 9.4 T” G. Shajan, J. Hoffmann, K. Scheffler, R. Pohmann, Proceeding of the ISMRM 2012 LINK

o Thorsten Liebig (Chair of Theoretical Electrical Engineering (ATE), University of Duisburg-Essen) - OpenEMS Project Overview
• The OpenEMS Simulation Software gives the user a FDTD Solver with a high performance for CPU calculation
• Circular Mesh-Grid available
• Now there are more MRI related examples
Related publications:
• Talk LINK
• "openEMS - A free and open source equivalent-circuit (EC) FDTD simulation platform supporting cylindrical coordinates suitable for the analysis of traveling wave MRI applications” T. Liebig, A. Rennings, S. Held, and D. Erni, Int. J. Numer. Model., 2012, DOI: 10.1002/jnm.1875

o Sigrun Goluch (MR Centre of Excellence of Medical University Vienna) - Simulation of a double tuned 1H/31P RF coil for the human calf at 7 T
• 31P transceiver coils in combinations with 1H transceiver coils for 7 T MRI
• Aim was a high decoupling between three 31P transceiver coils
• Capacitor on the shared conductor with overlapped 31P transceiver was the best compromise for load independency and constructive realization
Related publications:
“A multichannel ¹H/³¹P transmit-receive coil for spectroscopy in the human calf at 7T” S. Goluch, R. Kriegel, E. Moser, T. Herrmann, J. Mallow, J. Bernarding, K-N. Kim, S-M. Hong, H-B. Jeong, Z-H. Cho, E. Laistler, Proceedings of the ESMRMB 2012.

o Johannes Mallow (Department of Biometry and Medical Informatics, University of Magdeburg) - Simulation of Travelling Wave Application for 7 T Primate MRI
• The Travelling-Wave concept SAR evaluation for primate MRI with matched SAR Model
Related publications:
“Ultra-high field MRI for primate imaging using the travelling-wave concept” J. Mallow, T. Herrmann, KN. Kim, J. Stadler, J. Mylius, M. Brosch, J. Bernarding (2012) Magn Reson Mater Phy
- DOI: 10.1007/s10334-012-0358-z

Coffee Break

Open discussion:
o Question: For experience by the apply of the CST MWS “worst-case SAR” macro part of the MRI Toolbox
• Answer: only the phase but not the amplitude can varied
o Question: How is the performance of the CST Design Studio optimizer
• the outcome depends on the structure, start values, in some cases it don’t work or takes more time than manual optimization

o All participants have GPU acceleration in use
o Question: Which B1 mapping method is mostly used for coil validation?
• The AFI (Actual Flip angle Imaging) and pre-saturated FLASH is used
• AFI (TR > T1_max) is more accurate but pre-saturated FLASH is faster
• The Bloch-Siegert BURST is another B1 mapping and B1 interferometry method
Related publications:
• „SAR-reduced spin-echo-based Bloch-Siegert B(1)(+) mapping: BS-SE-BURST“, Basse-Lüsebrink TC et al., MRM, 2011
• “Multikanal B1+-Phasen und -Magnituden-Mapping mittels einer Bloch-Siegert-BURST Sequenz” A. Gotschy, UC. Hoelscher, TC. Basse-Luesebrink, T. Kampf, T. Herrmann, N.K. Darji, J. Bernarding, PM. Jakob, DS-ISMRM 2012

End of the Meeting 5.00pm
MR-EM Sim. Meeting protocol Essen ELH 2012.pdf
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