ELECTRONIC POSTER - ismrm

Thursday 13:30-15:30 Computer 43
13:30 3801. New High Dielectric Materials for Tailoring the B1-Distribution at High Magnetic
Field
Kristina Haines 1 , Nadine Smith 2 , Andrew Webb 2
1 Penn State University; 2 Radiology, Leiden University Medical Center, Leiden, Netherlands
The distribution of magnetic fields can be tailored using high dielectric materials. Here, we introduce a new material with high and
tunable dielectric constant, and also low background MRI signal. The material is based upon metal titanates, which can be made into a
geometrically-formable slurry by combining with deionized water. Results obtained at 7 Tesla show a significant increase in image
intensity in areas such as the temporal lobe and base of the brain.
14:00 3802. Capacitively Tunable Patch Antenna for Human Head Imaging at 9.4 Tesla
Jens Hoffmann 1 , Gunamony Shajan 1 , Rolf Pohmann 1
1 High Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tuebingen, Baden-
Wuerttemberg, Germany
Microstrip patch antennas, recently used for “traveling-wave” excitation at high field strengths, provide a fairly homogeneous
excitation pattern in the human head but have high power demands especially when the Larmor frequency is near or below the cutoff
frequency of the waveguide. In this work, we present a capacitively tunable patch antenna that can be brought in close proximity to the
subject in order to improve efficiency. We demonstrate the image homogeneity in the human head at 9.4 Tesla as well as a simulationbased
evaluation of the antenna’s efficiency and SAR depending on the distance to the subject.
14:30 3803. A 700MHz Receive Array Using Patch Antenna for Spin Excitation
Gunamony Shajan 1 , Jens Hoffmann 2 , Dávid Zsolt Balla 2 , Rolf Pohmann 2
1 High Field Magnetic Resonance Center , Max Planck Institute for Biological Cybernetics, Tuebingen, Baden
Wuttenberg, Germany; 2 High Field Magnetic Resonance Center, Max Planck Institute for Biological
Cybernetics, Tuebingen, Baden Wuttenberg, Germany
The availability of receive array coils at high field, small bore animal scanners is limited by the lack of space for classical transmit
volume resonators coupled with its inability to generate homogenous transmit B1 field due to wavelength effects. We explore the
possibility of the traveling wave concept for spin excitation along with the phased array technique for signal reception at 16.4T. To
this effect, a 3-channel phased array coil and a patch antenna were designed and combined. Signal to noise ratio and parallel imaging
techniques were studied and achieved SNR equivalent to that of a quadrature surface coil.
15:00 3804. Design and Numerical Evaluation of an 8-Element Quadrature Transceiver Array
Using Single-Feed CP Patch Antenna for Parallel Reception and Excitation
Yong Pang 1 , Chunsheng Wang 2 , Xiaoliang Zhang 2,3
1 Radiology and Biomedical imaging, University of California San Francisco, San Francisco, CA , United States;
2 Radiology and Biomedical imaging, University of California San Francisco, San Francisco, CA, United States;
3 UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco & Berkeley, CA, United States
An 8-element single-feed quadrature array is designed for 298 MHz using patch antenna technique. Each element is built as a nearly
square ring microstrip antenna and is fed along the diagonal to generate a circularly polarized (CP) magnetic field. Compared with
linear coils, the SNR can be improved by 40% or the transmission power can be reduced by half. Compared with conventional
quadrature coil, this structure is simple and easily built as array. FDTD simulations demonstrate that the decoupling between elements
are all better than -35dB and the RF field is homogeneous with deep penetration and quadrature behavior.
High Field Coils & Methods
Hall B Monday 14:00-16:00 Computer 44
14:00 3805. Open Design 8-Channel Tx/Rx Ankle Coil for High-Resolution and Real-Time
Imaging at 7 Tesla
Stephan Orzada 1,2 , Lena C. Schäfer 1,2 , Andreas K. Bitz 1,2 , Susanne C. Ladd 1,2 , Mark E.
Ladd 1,2 , Stefan Maderwald 1,2
1 Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, NRW, Germany; 2 Department of Diagnostic
and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, NRW, Germany
Since the introduction of parallel transmission techniques like transmit SENSE or RF shimming, arbitrarily shaped arrays can
potentially be used for excitation. Here we present an open U-shaped 8-channel transmit/receive strip line coil for 7 Tesla MRI
designed for simultaneous high-resolution and real-time joint imaging of the human ankle. The coil produced high quality, high
resolution images of the moving ankle during real-time imaging using an acceleration factor of four in the phase-encoding direction.