Boris Keil¹, Stephan Biber², Robert Rehner², Veneta Tountcheva¹, Kathrin Wohlfarth², Philipp Hoecht³, Michael Hamm³, Heiko Meyer², Hubertus Fischer², and Lawrence L Wald^1,4
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

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 Hargreaves^1
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.

Bei Zhang¹, Ryan Brown¹, Chris Wiggins², Daniel K Sodickson¹, Bernd Stoeckel³, and Graham Wiggins^1
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.

Hoby Patrick Hetherington¹, Nikolai I Avdievich¹, and Jullie W Pan^1
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.

Jens Oliver Hoffmann¹, Gunamony Shajan¹, and Rolf Pohmann^1
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.

Carl Jason Snyder¹, Lance DelaBarre¹, Gregory Metzger¹, Kamil Ugurbil¹, and J. Thomas Vaughan^1
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.

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 Berg^1
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.

Marcelino Bernardo^1,2, Gabriela Kramer-Marek³, Nalini Shenoy⁴, Jurgen Seidel¹, Michael V Green¹, Jacek Capala⁵, and Peter L Choyke^1
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.

Kirk Champagne¹, Wayne Schellekens¹, Mehran Fallah-Rad¹, Hongxiang Yi¹, Haoqin Zhu¹, and Labros Petropoulos^1
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.

Christin Y Sander^1,2, Boris Keil², Ciprian Catana², Bruce R Rosen^2,3, and Lawrence L Wald^2,3
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 -ray detection from the PET camera.