Receive Coils & Arrays
Click on to view the abstract pdf and click on to view the video presentation.
Monday May 9th
Room 520B-F  16:30 - 18:30 Moderators: Hiroyuki Fujita and Tamer Ibrahim

16:30 160.   A 64-Channel Array Coil for 3T Head/Neck/C-spine Imaging   -permission withheld
Boris Keil1, Stephan Biber2, Robert Rehner2, Veneta Tountcheva1, Kathrin Wohlfarth2, Philipp Hoecht3, Michael Hamm3, Heiko Meyer2, Hubertus Fischer2, and Lawrence L Wald1,4
1A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States,2Siemens Healthcare, Erlangen, Germany, 3Siemens Healthcare, Charlestown, MA, United States, 4Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States

Highly parallel array coils have been applied to the brain to improve sensitivity of accelerated and non-accelerated imaging, but also offer the possibility to extend the coverage to the neck and C-spine. We have developed a new head-neck-Cspine coil with 60 elements (with 4 additional elements used from the spine array) to improve the sensitivity of integrated head, neck and C-spine examinations. We validate the array with SNR and g-factor maps and accelerated imaging up to R=9

16:42 161.   Millimeter Isotropic Resolution Volumetric Pediatric Abdominal MRI with a Dedicated 32 Channel Phased Array Coil 
Shreyas S Vasanawala1, Thomas Grafendorfer2, Paul Calderon3, Greig Scott4, Marcus T Alley1, Michael Lustig5, Anja C Brau6, Arvind Sonik1, Peng Lai6, Vijay Alagappan7, and Brian A Hargreaves1
1Radiology, Stanford University, Stanford, CA, United States, 2ATD Coils, GE Healthare, Stanford, CA, United States, 3MR Hardware Engineering, GE Healthcare, Fremont, CA, United States, 4Electrical Engineering, Stanford University, Stanford, CA, United States, 5Electrical Engineering & CS, UC Berkeley, Berkeley, CA, United States, 6Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States, 7ATD Coils, GE Healthcare, Aurora, OH, United States

Pediatric abdominal MRI is challenged by small anatomy and limited patient cooperation. This work investigates the feasibility of utilizing a dedicated high-density pediatric body array to permit high resolution imaging with slices thin enough for adequate multiplanar reformatting. With IRB approval, 8 pediatric patients underwent abdominal MRI with a high-density coil, including coronal 3D T2, axial 2D T2, coronal 3D T1, and navigated axial 3D T1. 3D acquisitions were assessed for adequacy of SNR and reformat quality and found to be of diagnostic quality. Thus, a high-density coil may enable a rapid MRI protocol at millimeter resolution for pediatric body imaging.

16:54 162.   A 7T Coil System for Imaging Humans in the Sphinx Position to Evaluate the Effect of Head Orientation Relative to B0 for MR Imaging 
Bei Zhang1, Ryan Brown1, Chris Wiggins2, Daniel K Sodickson1, Bernd Stoeckel3, and Graham Wiggins1
1Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY10016, United States, 2CEA/NeuroSpin, Saclay, France,3Siemens Medical Solutions USA Inc, New York, NY, United States

We present a 7T coil system which allows the head to be rotated by greater than 90 degrees to investigate the effect of orientation upon the T2* contrast and B0 distribution in the brain. A patch antenna is used to create traveling wave excitation. The subject is placed in the ¡°sphinx¡± position with face towards the patch antenna. A six-element U-shaped receive coil was built to wrap over the crown of the head providing high enough SNR for high resolution T2* imaging. Imaging in regular supine position was also done for comparison.

17:06 163.   Multiplexed RF Transmission for Transceiver Arrays at 7T 
Hoby Patrick Hetherington1, Nikolai I Avdievich1, and Jullie W Pan1
1Neurosurgery, Yale University, New Haven, CT, United States

At 7T single drive volume coils suffer from poor homogeneity and low efficiency. Transceiver arrays using small surface coils provide improved homogeneity and transmission efficiency; however their use is limited by longitudinal coverage. This can be overcome by using multiple rows of coils along the z axis. However this approach requires an increasing number of independent transmit channels (one per coil), which is not available on most clinical platforms and is expensive. The goal of this work was to develop pulse sequence methods that enable small numbers of independent transmit channels to drive transceiver arrays with larger numbers of coils.

17:18 164.   Human Brain Imaging at 9.4 Tesla Using a Combination of Traveling Wave Excitation with a 15-Channel Receive-Only Array 
Jens Oliver Hoffmann1, Gunamony Shajan1, and Rolf Pohmann1
1High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tuebingen, BW, Germany

Traveling wave imaging using a Tx/Rx patch antenna has the potential to provide a more homogeneous B1+ field over a large field-of-view compared to circularly polarized volume coils. However, the method suffers from poor sensitivity which prevents the application to routine imaging. Therefore, we combined a patch antenna for transmission with a 15-channel receive-only array inside a narrow head gradient for human brain imaging at 9.4 Tesla. The setup can provide spin excitation covering the whole brain for low flip angle applications; high SNR and simple usage. However, anticipated advantages were spoiled by B1+ artifacts in our initial results.

17:30 165.   32-Channel Receive Only Array for Cardiac Imaging at 7T 
Carl Jason Snyder1, Lance DelaBarre1, Gregory Metzger1, Kamil Ugurbil1, and J. Thomas Vaughan1
1University of Minnesota, Minneapolis, MN, United States

A 32-channel receive-only array was designed and built for cardiac imaging. The parallel imaging performance, namely g-factors, was evaluated on the male pelvis. Short axis T-GRAPPA and four-chamber FLASH cines were acquired.

17:42 166.   Highly accelerated 7 T prostate imaging using parallel imaging 
Alexander J.E. Raaijmakers1, Ozlem Ipek1, Wouter Koning2, Hugo Kroeze2, Cecilia Possanzini3, Paul R. Harvey3, Dennis Klomp2, Peter R. Luijten2, Jan J.W. Lagendijk1, and Cornelis A.T. van den Berg1
1Radiotherapy, UMC Utrecht, Utrecht, Netherlands, 2Radiology, UMC Utrecht, Utrecht, Netherlands, 3Philips Medical Systems, Best, Netherlands

Prostate imaging at 7 Tesla suffers from high SAR levels and B1 signal attenuation. An array of 8 single-side adapted dipole antennas shows good signal coverage and is able to reduce the SAR levels by a factor of 4. In this work the parallel imaging performance of this array is characterized. The reference image is obtained by travelling wave imaging. GRE images are obtained using SENSE and reduction factors varying from 1 to 8. No folding artefacts are observed up to a reduction factor of 6 and g-factor values in the prostate stay within reasonable bounds for all reduction factors.

17:54 167.   Dual Mouse 8-Element Coil Array and Bed for Sequential Multimodality PET, SPECT, CT and MRI of Multiple Mice 
Marcelino Bernardo1,2, Gabriela Kramer-Marek3, Nalini Shenoy4, Jurgen Seidel1, Michael V Green1, Jacek Capala5, and Peter L Choyke1
1Molecular Imaging Program, NCI, Bethesda, MD, United States, 2SAIC-Frederick, Frederick, MD, United States, 3Radiation Oncology Branch, NCI, United States, 4Image Probe Development Center, NIH, United States, 5Radiation Oncology Branch, NCI, Bethesda, MD, United States

An 8-channel receive-only coil array for imaging two mice simultaneously and a two-mouse bed compatible with PET, SPECT, CT and MRI for use in doubling the throughput of sequential multimodality imaging of mice is described. Results of phantom tests and in vivo PET-MR imaging of a mouse tumor xenograft model are presented.

18:06 168.   A Novel Radiolucent Phased Array Design Suitable for MR Guided Radiation Therapy 
Kirk Champagne1, Wayne Schellekens1, Mehran Fallah-Rad1, Hongxiang Yi1, Haoqin Zhu1, and Labros Petropoulos1
1IMRIS Inc., Winnipeg, MB, Canada

A novel design of an 8-channel radiolucent phased array for MR guided Radiation Therapy is presented. The proposed design exhibits superior MR performance characteristics when compared with the equivalent aluminum design. In addition, the proposed design exhibits a uniform X-ray transparency image with no apparent distinction between the copper and its surrounding substrate. Volunteer imaging was also performed indicating that the proposed structure can be ideal for abdominal imaging.

18:18 169.   Design Criteria of an MR-PET Array Coil for Highly Parallel MR Brain Imaging 
Christin Y Sander1,2, Boris Keil2, Ciprian Catana2, Bruce R Rosen2,3, and Lawrence L Wald2,3
1Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, 3Health Sciences and Technology, Harvard-MIT, Cambridge, MA, United States

The construction of a parallel phased array MR brain coil that is compatible with the state of the art simultaneous MR-PET Brain scanners requires unique material and design specifications. In this study, we evaluate the design criteria of a 32-channel MR-PET coil (including conductor materials, cable thicknesses and component placements with experiment and simulation) to improve SNR and parallel imaging of MR while minimizing the interference with 511 keV lower case Greek gamma-ray detection from the PET camera.