ISMRM 21st Annual Meeting & Exhibition 20-26 April 2013 Salt Lake City, Utah, USA

Hybrid Systems
Friday 26 April 2013
Room 250 BCEF  10:30 - 12:30 Moderators: Blaine A. Chronik, Fraser J. L. Robb

10:30 0824.   A 16-Channel Breast RF-Coil for Simultaneous PET/MR
Manoj M. Nimbalkar1, Matthias Müller2, Titus Lanz2, Stephan G. Nekolla1, Sibylle Ziegler1, Rebekka Kraus1, Sebastian Fürst1, Axel Haase3, Markus Schwaiger1, and Isabel Dregely1
1Klinikum rechts der Isar, Technischen Universität München, München, Bayern, Germany, 2RAPID Biomedical GmbH, Rimpar, Germany,3Zentralinstituts für Medizintechnik, Technische Universität München, München, Bayern, Germany

Novel hybrid systems such as PET/MR can simultaneously provide metabolical and anatomical information in breast cancer imaging. Here we present design and implementation of a 16-channel breast RF coil optimized for simultaneous PET/MR (3T) systems. In phantom studies we found that the MR performance of the PET/MR coil was comparable to MR-only coils. Accurate PET quantification could be achieved with the PET/MR breast coil in the PET FOV by implementing a CT-based template-attenuation correction (AC) map of the coil to be combined with the MR-acquired phantom-AC map.

10:42 0825.   A PET Optimized 16-Element Anterior Array Coil for 3T Simultaneous MR/PET System
Yun-Jeong Stickle1, Tae-Young Yang1, Tom E. Zink1, Sahil Bhatia1, Victor Taracila1, Fraser Robb1, Bijay K. Shah2, and David M. Goldhaber2
1Engineering, GE Healthcare, Aurora, OH, United States, 2Engineering, GE Healthcare, Waukesha, WI, United States

A PET optimized 16- Element anterior array coil is described for acquiring high-sensitivity MR (Magnetic Resonance) images and good quality PET images of the torso and cardiac at 3 Tesla simultaneous PET/MR system. This anterior coil has been optimized to minimize the interference with gamma ray detection from the PET without scarifying MR image quality. In this study, we reduced the thickness of the rigid coil formers that consist of a Lexan 940 with the PET transparent material supports, optimized arrangement of components (internal cables, internal cable baluns, feedboards and decoupling boards) and introduced the new mechanical feedboard and decoupling housing design.

10:54 0826.   
Low 511keV-Attenuation Array Coil Setup for Simultaneous PET/MR Imaging of the Monkey Brain
Christin Y. Sander1,2, Avilash Cramer1, Boris Keil1, Azma Mareyam1, Bruce R. Rosen1,3, and Lawrence L. Wald1,3
1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, 2Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, 3Health Sciences and Technology, Harvard-MIT, Cambridge, MA, United States

Simultaneous PET/MR imaging of non-human primates is challenging due to the lack of dedicated coils that are needed to target smaller brain volumes and allow for increased resolution without a loss in sensitivity. Moreover, the attenuation properties of coils are an important design parameter to ensure PET imaging with minimal artifacts. In this study, we developed two monkey coils of different sizes that minimized 511 keV attenuation and showed superior sensitivity and acceleration compared to the alternative use of a human head coil.

11:06 0827.   3T Head Neck Coil for Simultaneous MR-PET Imaging
Sahil Bhatia1, Gabriel Searles2, Dmitriy Londarskiy2, Tom E. Zink2, Darren Gregan2, Tae-Young Yang2, Bijay Shah3, and Yun-Jeong Stickle2
1GE Healthcare, Aurora, OH, United States, 2G.E. Healthcare, Aurora, OH, United States, 3G.E. Healthcare, Waukesha, WI, United States

MR-PET combines the advantages of MRI’s morphological imaging with excellent soft tissue contrast and PET’s functional imaging. Integrated MR-PET scanners offer several advantages over sequential scanners such as reduction in overall scan time and elimination of patient repositioning. In an integrated MR-PET system, phased array surface coils are directly in the PET field of view and attenuate positrons resulting in artifacts and poor quality PET images. This paper presents a head neck coil at 3T designed specifically to be transparent to PET positrons. Significant improvements in PET sensitivity loss are shown without loss in MR performance.

11:18 0828.   Highly Efficient Inductively Coupled Double Resonant Surface Coil for Simultaneous 1H/19F PET-MRI -permission withheld
Christian Findeklee1, Christoph Leussler1, Daniel Wirtz1, and Jochen Keupp1
1Research Laboratories Hamburg, Philips Technologie GmbH, Hamburg, Germany

A PET compatible 1H/19F surface coil was realized by an adjustable dual resonant inductive coupling loop. This concept enables convenient and accurate tuning and matching across a wide variety of different loading scenarios. In addition, the inductive coupling mechanism integrates a cable trap function. Furthermore, the stray field of the feeding loop is exactly the same at both operating frequencies. The coil was designed such that it is merely transparent for PET imaging.

11:30 0829.   
MR-PET Respiration Compensation Using Self-Gated Motion Modeling
Robert Grimm1, Sebastian Fürst2, Isabel Dregely2, Stephan G. Nekolla2, Sibylle Ziegler2, Simon Bauer3, Dominik Nickel3, Berthold Kiefer3, Joachim Hornegger1, Markus Schwaiger2, and Kai Tobias Block4
1Pattern Recognition Lab, FAU Erlangen-Nuremberg, Erlangen, Germany, 2Department of Nuclear Medicine, Technische Universität München, Munich, Germany, 3Siemens Healthcare, Erlangen, Germany, 4Department of Radiology, NYU Langone Medical Center, New York City, NY, United States

First in-vivo results of respiratory motion compensation in hybrid PET-MRI systems are presented. With the help of self-gated reconstructions of a 3D radial stack-of-stars GRE sequence, a motion model can be generated from the MR images. The derived self-gating signal also allows motion-binned PET reconstruction. The motion model is applied to warp the µ-map to different respiratory levels as well as to perform motion correction in the reconstructed PET images. The resulting images show better lesion delineation and sharpness of the liver dome compared to uncorrected reconstructions.

11:42 0830.   
Simultaneous PET/MR Imaging: Automatic Attenuation Correction of Flexible RF Coils
René Kartmann1, Daniel H. Paulus1, Bassim Aklan1, Susanne Ziegler1, Harald Braun1, Bharath Navalpakkam1, and Harald H. Quick1
1Institute of Medical Phyics, Erlangen, Bavaria, Germany

Flexible RF surface coils used in simultaneous PET/MR imaging attenuate the PET signal and are currently not attenuation corrected. An algorithm is presented, which automatically integrates CT-based attenuation maps of flexible surface coils into PET attenuation correction. Registration is based on markers. Two phantoms are scanned with/out RF coils placed on top. Considerable local attenuation due to the presence of the coils was measured in regions close to the coils. The combined attenuation maps generated by the presented algorithm perform well concerning the attenuation correction of the coils. Furthermore, volunteer scans provide evidence that the algorithm is accurate and robust.

11:54 0831.   Modular Rotating Gamma Camera Insert for Simultaneous SPECT and MR Small-Animal Imaging
Mark Jason Hamamura1, Seunghoon Ha2, Werner W. Roeck1, James W. Hugg3, Dirk Meier4, and Orhan Nalcioglu1,5
1Tu & Yuen Center for Functional Onco-Imaging, University of California, Irvine, CA, United States, 2Tu & Yuen Center for Functional Onco-Imaging, University of California Irvine, Irvine, CA, United States, 3Gamma Medica, Inc., Northridge, CA, United States, 4Gamma Medica, Inc., Fornebu, Norway, 5Department of Cogno-Mechatronics, Pusan National University, Busan, Korea

We have developed a modular rotating gamma camera insert that has been designed for straightforward integration with existing MRI systems for simultaneous SPECT and MR imaging. Operation of the combined system was demonstrated through phantom and small animal imaging. Due to its versatility, we anticipate that this system can be utilized for a wide range of small-animal imaging applications.

12:06 0832.   
A 10-Channel RF Coil for Use in Magnetic Resonance Guided High Intensity Focused Ultrasound of the The Brain.
Emilee Minalga1, Robb Merrill1, Nick Todd1, Dennis L. Parker1, and J. Rock Hadley1
1Department of Radiology, University of Utah, Salt Lake City, UT, United States

This work describes the design of an open access 10-channel brain RF coil for magnetic resonance guided high intensity focused ultrasound. The coil was built to be compatible with a head stereotactic device and waterproof for use in a water tank. This coil uses capacitive decoupling of adjacent loops. The coil is evaluated for SNR performance, temperature imaging performance, and a comparison of anatomy scans. The coil was found to give better SNR over the body coil. This SNR increase translates to better anatomy imaging and temperature measurements.

12:18 0833.   Hybrid MRI/RF-Heating at 7.0 Tesla and 11.7 Tesla: Electro-Magnetic Field Simulations, Temperature Simulations/Measurements, Dipole Antenna Design and Heating Experiments
Lukas Winter1, Tessa van de Lindt1, Celal Özerdem1, Werner Hoffmann2, Davide Santoro1, Alexander Müller1, Andreas Graessl1, Reiner Seemann2, Jaroslav Marek1, and Thoralf Niendorf1,3
1Berlin Ultrahigh Field Faciltiy (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Berlin, Germany, 2Metrology in Medicine, Physikalisch Technische Bundesanstalt, Berlin, Germany, 3Experimental and Clinical Research Center (ECRC), a joint cooperation between Charité Medical Faculty and Max-Delbrück Center for Molecular Medicine, Berlin, Germany

The concept of combining dedicated MR hardware for MR imaging, MR thermometry and targeted RF heating at 7.0T has been demonstrated recently. This study examines controlled RF induced heating at even higher frequencies (11.7T), to benefit from the sharpening and focusing abilities of a RF wavelength reduction. The presented antenna configurations both for 7.0T and 11.7T are suitable for MR imaging, MRTh and targeted RF-Heating. Temperature simulations in voxel models show, that a controlled generation of a hotspot in the human brain is feasible and the hotspot dimensions can be further reduced with an increase in frequency.