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Hall B Monday 14:00-16:00 Computer 43 Wouter Koning1, Hugo Kroeze, 2, Bart Leo van de Bank, Vincent O. Boer, Cornelis A. van den Berg, Jaco J. Zwanenburg, Peter R. Luijten, Dennis W. Klomp 1Radiology, UMC Utrecht, Utrecht, Netherlands; 2MTKF In high field MRI, acceleration with parallel imaging in MRI can be a challenge as homogeneous reference scans are difficult to obtain. Traveling wave MRI can be applied for the acquisition of reference images. This enables acceleration with parallel imaging even with RF coil setups that are optimized for sensitivity only. Here, a proof of principle is given at 7T using a quadrature antenna for acquisition of the reference images, together with an array of dedicated surface coils for carotid artery imaging. 14:30 3790. A Novel Matching Strategy to Increase Power Efficiency of the Travelling Wave MR Imaging Anna Andreychenko1, Hugo Kroeze2, Dennis W. Klomp2, Jan J. Lagendijk1, Peter Luijten2, Cornelius A.T. van den Berg1 1Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands; 2Radiology, University Medical Center Utrecht, Utrecht, Netherlands Travelling wave MR imaging exploits the RF shield of the scanner as a waveguide. When a patient is placed in the bore a strong impedance mismatch occurs between the hollow (where antenna is located) and loaded parts of the bore. It causes wave reflection and inefficient power is transferred to the target region. To avoid this impedance mismatch we propose to insert a quarter-wavelength coaxial waveguide between the antenna and load which gradually transforms impedance of the antenna to the load impedance. The effectiveness of this inset has been demonstrated both in the simulations and in-vivo experiments. 15:00 3791. Shortened Quarter Lambda Antenna for Traveling Wave Excitation in High Field MRI Hugo Kroeze1,2, Anna Andreychenko3, Cornelis A.T. van den Berg3, Dennis W.J. Klomp1, Peter R. Luijten1 1Radiology, UMC Utrecht, Utrecht, Netherlands; 2Medical Technology, UMC Utrecht, Utrecht, Netherlands; 3Radiotherapy, UMC Utrecht, Utrecht, Netherlands A patch antenna can be used for travelling wave excitation in high field MRI. Due to its size, this antenna has to be placed at the far end of the bore, reducing it efficiency when imaging in the abdominal area. A Shortened Quarter Lambda antenna is proposed to overcome this problem. By placing the SQL antenna between the lags of the patient, an 8 fold improved efficiency can be demonstrated in the abdomen, compared to a patch antenna. Images of the prostate and the head of a healthy volunteer are presented. 15:30 3792. Waveguide Magnetic Resonance Imaging at 3 Tesla F Vazquez1, R Martin1, O Marrufo1, Alfredo O. Rodriguez1 1Departament of Electrical Engineering, Universidad Autonoma Metropolitana Iztapalapa, Mexico, DF, Mexico Waveguides have been successfully used to generate magnetic resonance images at 7 Tesla for whole-body systems. From these results, it has been established that waveguides are only suitable for 7T systems with wide bores of al least 60 cm. This is mainly due to the cut-off frequency of the cylindrical waveguides used. To overcome this limitation a parallel-plate waveguide was employed since its cut-off frequency depends on the separation of the plates. A parallel-plate waveguide was built and used to acquire images of a healthy volunteer’s leg at 3 Tesla on a clinical MR imager. Tuesday 13:30-15:30 Computer 43 13:30 3793. A Traveling-Wave Setup for Parallel RF Transmission Jan Paska1, David Otto Brunner2, Klaas P. Pruessmann2, Ingmar Graesslin3, Juerg Froehlich1, Ruediger Vahldieck1 1Laboratory for Electromagnetic Fields and Microwave Electronics, ETH Zurich, Zurich, Switzerland; 2Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; 3Philips Research Europe, Hamburg, Germany The traveling wave concept for ultra high field MRI offers a large FOV and patient space. Only the two TE11 modes can propagate in an empty bore at 7T. To extend the traveling wave concept for parallel transmission also the higher order modes are needed, increasing the degrees of freedom. This is done by lowering the cut-off frequencies of the higher order modes with dielectric inserts. Selective coupling into the orthogonal waveguide modes is desirable. This is however a demanding task in a multimodal waveguide, as known from optics. Yong Pang1, Chunsheng Wang2, Daniel Vigneron2,3, Xiaoliang Zhang2,3 1Radiology and Biomedical imaging, University of California San Francisco, San Francisco, CA , United States; 2Radiology and Biomedical imaging, University of California San Francisco, San Francisco, CA, United States; 3UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco & Berkeley, CA, United States Traveling-wave MRI utilizes the far field of a single piece patch antenna to generate homogeneous RF field covering large size imaging samples. In this work, we demonstrate a method to applying the “traveling wave” technology to parallel excitation and reception by using a multi-element patch antenna array. Each array element is a CP patch antenna which generates quadrature RF fields. FDTD simulation results demonstrate the excellent decoupling among elements, great g-factors at various reduction factors for 1D SENSE, demonstrating the feasibility of parallel imaging using traveling-wave. 14:30 3795. Targeted Travelling Wave MRI Using a Coaxial Waveguide Stefan Alt1, Marco Müller1, Reiner Umathum1, Michael Bock1 1Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany In high field MRI with volume resonators, image quality suffers from the appearance of standing wave patterns. We propose the use of a coaxial waveguide with interrupted inner conductor to guide the RF energy to the designated imaging region. These targeted travelling waves can achieve a more homogenous excitation and reduce SAR outside the FOV. Feasibility of the method is assessed with RF field simulations using a detailed anatomical model as well as with a hardware prototype. Transverse magnetic field and SAR distributions are shown and evaluated on the simulated data and an image from the hardware prototype is shown. 15:00 3796. Optimization of Radiative Surface Antenna for High Field Mri Özlem Ipek1, Alexander J.R. Raaijmakers1, Jan J. Lagendijk1, Cornelis A.T van den Berg1 1Radiotherapy and Radiology, UMC Utrecht, Utrecht, Netherlands A novel radiative surface antenna consists of two copper strips placed on a dielectric rectangular substrate. It is investigated by means of electromagnetic modeling of the substrate material and the conductor dimensions in terms of impedance matching, effective B1+ delivery at depth and low local SAR. Such antenna design requires that its Poynting vector is directed into the target location and a dielectric substrate that ensures impedance matching at the antenna-body interface. When the dielectric constant of substrate is matched to that of the phantom, the radiative antenna is matched to 50 Ohm, thus its radiation efficiency is the highest. Wednesday 13:30-15:30 Computer 43 Tim Herrmann1, Johannes Mallow1, Jörg Stadler2, Oliver Speck3, Matthias Kladeck3, Johannes Bernarding1 1Department of Biometry and Medical Informatics, OvG University, Magdeburg, Saxony-Anhalt, Germany; 2Leibniz-Institute for Neurobiology, Magdeburg, Germany; 3Biomedical Magnetic Resonance, OvG University, Magdeburg, Saxony-Anhalt, Germany Goal of this study was to expand the abilities of the Travelling Wave concept in Ultra-Highfield MRI, to get an efficient body coil replacement in the future, by using the advantage of a bigger diameter and an extended length of the RF-shield. Promising results are shown by using the turnstile dipole antenna as Tx and a phased array RF-coil for Rx. The highest SNR can be achieved under Travelling Wave conditions because the B1-filling factor for phased array RF-coil is much better. 14:00 3798. MRI of the Human Torso at 7 Tesla Using Dual Quadrature Patch Antennas. Andrew Webb1, Nadine Smith1 1Radiology, Leiden University Medical Center, Leiden, Netherlands Whole-body imaging at high magnetic fields presents a variety of engineering challenges arising mainly from the short wavelength of electromagnetic radiation in the human body. One successful solution has been to use multi-transmit arrays with the magnitude and phase of the driving signal to each array element under operator control. In this work we present an alternative and simple approach which uses two large patch antennas, both driven in quadrature, which essentially form a large distributed microstrip. Using this hardware configuration, homogenous low-tip angle gradient echo images can be acquired through the abdomen and cardiac regions of the body. 14:30 3799. A Novel Radiative Surface Antenna for High Field Mri Özlem Ipek1, Alexander J.R. Raaijmakers1, Dennis W.J. Klomp1, Jan J. Lagendijk1, Cornelis A.T van den Berg1 1Radiotherapy and Radiology, UMC Utrecht, Utrecht, Netherlands A radiative surface antenna is compared to a stripline element in terms of measured and simulated B1+ field and simulated SAR. The radiative antenna is suitable for high field imaging of deeply situated organs and designed to effectively couple an electromagnetic wave into the body. It consists of a dielectric substrate with two copper strips fed by a coaxial cable. Due to the radiative principle, the radiative antenna shows two times higher B1+ field at depth of the phantom as well as six times lower maximum SAR at the surface of the phantom in comparison to a conventional stripline element. 15:00 3800. Near- And Far-Field Measurements of Strip Conductor-Type Coils for 7-Tesla MRI Klaus Solbach1, Stephan Orzada2, Pedram Yazdanbakhsh1 1Radio Frequency Technology, University Duisburg-Essen, Duisburg, Germany; 2University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany Measurements of the electric and magnetic near-fields of our 7 Tesla strip conductor-type coils are presented using probes travelling on a linear scanning mechanism in our antenna test chamber. In addition, the far-field patterns and gain were measured and it is found that the coils behave much like stripline antennas with strong radiation fields. The measurements of the near-fields of a dipole- and loop-type coil shows important differences in the field levels and distributions with higher B1- flux levels and more concentrated spatial distribution as well as lower E-field levels in the dipole-type. Thursday 13:30-15:30 Computer 43 13:30 3801. New High Dielectric Materials for Tailoring the B1-Distribution at High Magnetic Field Kristina Haines1, Nadine Smith2, Andrew Webb2 1Penn State University; 2Radiology, 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 Hoffmann1, Gunamony Shajan1, Rolf Pohmann1 1High 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 simulation-based 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 Shajan1, Jens Hoffmann2, Dávid Zsolt Balla2, Rolf Pohmann2 1High Field Magnetic Resonance Center , Max Planck Institute for Biological Cybernetics, Tuebingen, Baden Wuttenberg, Germany; 2High 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. Yong Pang1, Chunsheng Wang2, Xiaoliang Zhang2,3 1Radiology and Biomedical imaging, University of California San Francisco, San Francisco, CA , United States; 2Radiology 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. Hall B Monday 14:00-16:00 Computer 44 Stephan Orzada1,2, Lena C. Schäfer1,2, Andreas K. Bitz1,2, Susanne C. Ladd1,2, Mark E. Ladd1,2, Stefan Maderwald1,2 1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, NRW, Germany; 2Department 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. 14:30 3806. A 8 Channel TX/RX Decoupled Loop Array for Cardiac/body Imaging at 7T Wolfgang Renz1,2, Tomasz Lindel2,3, Matthias Dieringer2,4, Frank Seifert2,3, Jeanette Schulz-Menger2,5, Thoralf Niendorf2,4, Bernd Ittermann2,3 1Siemens AG, Erlangen, Germany; 2Berlin Ultrahigh Field Facility, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany; 3Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany; 4Experimental and Clinical Research Center, Charite Campus Buch, Berlin, Germany; 5CMR-Unit, Charite Campus Buch, Berlin, Germany The first steps in cardiac/body imaging at 7T have been reported. One of the challenges is a suitable TX coil concept, which addresses the RF problems (B1 homogeneity, SAR) of body imaging at 300MHz. Traditional bodycoils seem not to be the right way, a coil array enabling TX SENSE and B1 shimming seems to be more promising. We describe a 8-element TX/RX loop coil array with adjustable capacitive decoupling. A prototype has been realised and tested. First imaging results in cardiac imaging are shown. Ryan Brown1, Bernd Stoeckel2, Daniel K. Sodickson1, Graham C. Wiggins1 1Radiology, Center for Biomedical Imaging, NYU School of Medicine, New York, NY, United States; 2Siemens Medical Solutions USA Inc., New York, NY, United States 7T torso imaging has been hindered by non-uniform B1+ distribution and inadequate B1+ in the center of the torso. Stripline coils are the preferred method for RF excitation at 7T and have shown promise for torso imaging. Nevertheless, loop coils have not been compared to striplines in the context of torso imaging. In this study, B1+ was measured using several single element prototype coils and an array of stripline/loop combination coils. Results showed that the stripline array offers improved transmit efficiency near the surface while loop coils may provide a marginal advantage at depth. Alexander Raaijmakers1, Bob van den Bergen1, Dennis Klomp2, Catalina Arteaga de Castro2, Vincent Boer2, Hugo Kroeze2, Peter Luijten2, Jan Lagendijk1, Nico van den Berg1 1Radiotherapy, UMC Utrecht, Utrecht, Netherlands; 2Radiology, UMC Utrecht, Netherlands In this study, we compare a 8-stripline coil array with a endorectal coil. FDTD simulations are performed to evaluate the SAR deposition of both coils. Given the power restrictions due to these SAR levels, the suitability of the coils is tested for three common imaging protocols for prostate cancer: a T1w image, a T2w image and MR spectroscopy. Results show that a surface coil array is needed for T1w and T2w images, while the endorectal coil is needed for spectroscopy. Tuesday 13:30-15:30 Computer 44 13:30 3809. B1 Shimming Using Passive Surface Coils in the Abdomen Laura Sacolick1, Pekka T. Sipilae1, Mika W. Vogel1, Ileana Hancu2 1GE Global Research, Garching b. Munchen, Germany; 2GE Global Research, Niskayuna, NY, United States Here we present a simple approach for improving B1 homogeneity in the abdomen at 3 Tesla. 3D B1 maps were acquired from 6 subjects in the lower abdomen from the GE HDx whole body transmit coil. The B1 in the abdomen had very similar distributions in all subjects studied. The average B1 distribution among these subjects was used to design and place two tuned passive loop coils to couple to the transmit field and increase the B1 field in regions of low B1. One loop was tuned to 136.5 MHz and placed on the anterior, and one tuned to 141.0 MHz was placed on the posterior abdomen. Significant improvement was found in the transmit B1 field homogeneity in subjects with the corrective coils. 14:00 3810. Reduction of B1 Inhomogeneity Using B1 Rectifying Fin at High Fields - not available Yukio Kaneko1, Hideta Habara1, Yoshihisa Soutome1, Yoshitaka Bito1 1Central Research Laboratory, Hitachi, Ltd., Kokubunji-shi, Tokyo, Japan B1 inhomogeneity in a human body increases as static magnetic field strength becomes higher, and various RF control methods have been developed to reduce B1 inhomogeneity. However, B1 inhomogeneity still remains in some cases of abdominal imaging, and a more effective method is necessary. We have proposed a new method using a gB1 rectifying finh combined with B1 shimming. Both electromagnetic simulation with phantom and experiments with a human abdomen were conducted, and we confirmed that the B1 rectifying fin, used with B1 shimming, was more effective in reducing B1 inhomogeneity than B1 shimming alone. 14:30 3811. An Eight-Channel Tx/Rx Multi-Purpose Coil for MSK MR Imaging at 7 Tesla Oliver Kraff1,2, Andreas K. Bitz1,2, Philipp Dammann1,3, Lena C. Schaefer1,2, Mark E. Ladd1,2, Susanne C. Ladd1,2, Harald H. Quick1,4 1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany; 2Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany; 3Clinic for Neurosurgery, University Hospital Essen, Essen, Germany; 4Institute for Medical Physics, Friedrich-Alexander-University Erlangen-Nuernberg, Erlangen, Germany An eight-channel transmit/receive RF array was built for imaging peripheral regions of the musculoskeletal system that have not been addressed at 7T so far. The array consists of two coil clusters, made of four overlapping loop coils each, to enable flexible positioning on the human body. Numerical simulations were performed for safety validation. We show in vivo results of the human wrist, shoulder, elbow and ankle revealing good excitation over a 180mm field-of-view. Not only GRE but also typical clinical sequences like STIR and TSE performed very well. Imaging of small pathologies (cartilage, ligaments, nerves) could benefit from this technique. 15:00 3812. Development of Quadrature Transmit Elements for Breast MRI/MRSI at 7T - not available Ananda Kumar1, LeRoy Blawat1, Michael Schär2, Peter Barker3 1Resonant Research LLC., Baltimore, MD, United States; 2Philips Healthcare, Cleveland, OH, United States; 3Radiology, Johns Hopkins University, Baltimore, MD, United States Two critical challenges encountered in the development of MR transmit elements at very high field strengths are RF power deposition and excitation field homogeneity. A quadrature transmit loop elements pair was developed for 7T breast MRI/MRSI using full-wave numerical EM methods. Field homogeneity and SAR values are accurately predicted by the EM methods employed and facilitates in the development of transmit elements for breast MR with improved field homogeneity with appropriate RF safety limits. The performance of the coil was successfully evaluated on an agar gel phantom and on a healthy volunteer. Wednesday 13:30-15:30 Computer 44 Frank Seifert1,2, Tomasz Dawid Lindel1,2, André Kuehne1,2, Helmar Waiczies1,2, Wolfgang Renz, 23, Bernd Ittermann1,2 1Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, D-10587 Berlin, Germany; 2Berlin Ultrahigh Field Facility, Max-Delbrück-Center for Molecular Medicine, D-13125 Berlin, Germany; 3Siemens Healthcare, D-91052 Erlangen, Germany Tx-SENSE performance depends crucially on the reliable knowledge of the transmit sensitivity maps of the coil elements. For 7T body imaging the virtual reference approach fails to get reliable maps. This was shown for a simulated Tx-SENSE based zoomed cardiac imaging experiment at 7T. FDTD simulations were performed for a experimental 4-channel TX/RX coil array. Using either the virtual reference approach or the true sensitivity maps two sets of RF pulse shapes were calculated for a box like excitation pattern covering the heart. For both RF pulse sets the flip angle distribution was calculated from a full Bloch Equation simulation. David Otto Brunner1, Clemens Grassberger1, Klaas Paul Pruessmann1 1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland Small receiver loop coils offer high SNR gain and are therefore common practice in MRI and MRS. In this work it was tried to optimize the conductor geometry and size of such loop coils comparing a series of conical coils with varying shell angles, diameters and placements. Furthermore the dependence of these parameters on the dielectric properties of the sample has been studied, which turned out to have a major impact at these frequencies. 14:30 3815. Reducing SAR and Enhancing SNR with High Permittivity Dielectrics (ε) at 3T Qing X. Yang1,2, Jianli Wang1, Jinghua Wang3, Chunsheng Wang1, Christopher M. Collins1, Michael B. Smith4 1Radiology, Penn State University College of Medcine, Hershey, PA, United States; 2Neurosurgery, Penn State University College of Medicine, Hershey, PA, United States; 3Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, United States; 4Novartis Institutes for BioMedical Research, Inc. Experimental results of human head imaging at 3T showed that padding around the human head containing appropriate amount of high dielectric material (~ 70) such as water reduced the input RF power for an 180° excitation pulse by 50% while enhancing image SNR by as much as 40%. Our experimental results demonstrated that placement of high ε pad enhanced B1 in the head and, thus, offers an effective approach for RF engineering. 15:00 3816. A 7T ‘Capless’ Transceive Breast Coil Bing Keong Li1, Hua Wang1, Ewald Weber1, Yu Li1, Adnan Trakic1, Daniel James Lee2, Sedig Farhat2, Paul Glover2, Richard Bowtell2, Stuart Crozier1 1School of ITEE, The University of Queensland, Brisbane, Qld, Australia; 2School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom A new method for designing a ultra high field bilateral transceive breast coil is presented. The design method does not require any discrete capacitors (hence the name “Capless Transceive Breast Coil”) and can be driven by a single RF port for simultaneous bilateral breast imaging. A prototype breast coil using this design method was constructed and tested in a 7T Philips whole-body MRI system. Phantom images acquired using the prototype show high homogeneity and excellent RF penetration. Thursday 13:30-15:30 Computer 44 13:30 3817. A Distributed Impedance Model for the Shielded 7T Inductive Head Coil Joseph Murphy-Boesch1 1NINDS/LFMI, National Institutes of Health, Bethesda, MD, United States The isolated meshes of the Inductive Resonator couple via strong mutual inductance to develop a “high-pass” distribution of modes for the coil. While simple mutual inductive coupling of neighboring meshes can accurately fit the modes of low frequency resonators, this model does not work for the shielded 7T head coil. Here, a transmission line and distributed impedance model is developed for the shielded 7T inductive resonator that accurately describes its modes and provides a model for high-frequency design. 14:00 3818. 31P Spectroscopy in Human Calf Muscle at 7 Tesla Using a Balanced Double-Quadrature Proton-Phosphorus RF Coil Andrew Webb1, Nadine Smith1 1Radiology, Leiden University Medical Center, Leiden, Netherlands In order to obtain high quality 31P data from human calf muscle, we have designed a closely-fitting double-tuned half-volume coil with quadrature on both 1H and 31P channels. Balanced, second order trap circuits are inserted into the heteronuclear coil to prevent counter-currents from being set up at the proton frequency, thus improving the efficiency of the proton channel. 2D 31P CSI data sets have been obtained at 7 tesla using this coil, with high signal-to-noise. 14:30 3819. Loop T/R Coil for 7T MRI/MRS with Two Transmit/Receive Channels - not available Zhiyong Zhai1, Michael Morich1, William Braum1 1Philips Healthcare, Cleveland, OH, United States We propose a coil structure topologically similar to the single loop coil but with distinctly different operational characteristics. It has two concentric flat rings which can be tuned to two orthogonal resonant modes at the same frequency. Combining with two independent transmit/receive (T/R) channels for B1 shimming, a more uniform B1-field coverage in the sensitive region of the coil is achieved. The proposed coil can easily be used for various imaging purposes at different anatomies such as head, torso and extremities at 7T. 15:00 3820. Quadrature Surface Coils for in Vivo Imaging in 900-MHz Vertical Bore Spectrometer Barbara L. Beck1,2, Jose A. Muniz, 23, Ihssan S. Masad, 23, Samuel C. Grant, 23 1McKnight Brain Institute, University of Florida, Gainesville, FL, United States; 2National High Magnetic Field Lab, Tallahassee, FL, United States; 3Chemical & Biomedical Engineering, Florida State University, Tallahassee, FL, United States As MRI continues to evolve to higher static fields, radio frequency coil design must keep pace. Clockwise and counter clockwise field components must be considered when predicting signal intensity distributions. The magnetic fields of quadrature coils at 500 MHz and 900 MHz were simulated for the calculation of rotating components and simulated images. In addition, coils were constructed and tested in vertical bore magnets at 11.7 and 21.1 T. SNR of acquired images indicated 30% gain of quad coils over linear and approximately linear increase of SNR from 500 to 900 MHz. Hall B Monday 14:00-16:00 Computer 45 Tamer S. Ibrahim1, Tiejun Zhao2, Eric Jefferies3, Hai Zheng3, Fernando E. Boada4 1Departments of Bioengineering and Radiology, Univeristy of Pittsburgh, Pittsburgh, PA, United States; 2Siemens Medical Solutions; 3Department of Bioengineering, University of Pittsburgh; 4Department of Radiology, University of Pittsburgh Several major obstacles have dampened the enthusiasm for widespread implementation of parallel transmission methods for ultrahigh field imaging including: 1) the need for accurate B1+ field mapping, 2) coil and subject dependent increases in local/global SAR, and 3) concerns regarding the unclear RF safety assurance of the PTX experiment due to inappropriate electromagnetic models for the estimation of the SAR at ultra-high. The work aims at alleviating these issues through the extension of the 4-port Tic Tac Toe coil to a more elaborate (covers the whole head volume,) 8-20 Tx channel, subject insensitive array for imaging at ultra high fields. 14:30 3822. Separated Volume Transmit / Volume Receive Arrays for Use in a 7T Head Gradient Lance J. DelaBarre1, Scott Schillak1, Brandon Tramm1, Carl J. Snyder1, J. Thomas Vaughan1 1CMRR - Radiology, University of Minnesota, Minneapolis, MN, United States Head gradients constrain the dimensions of RF coils. Two 7T transmit TEM volume coils, one inductively coupled, one decoupled for parallel transmit, were designed to fit the head gradients. Each coil was equipped with an actively detuned, pre-amplifier decoupled, volume receiver array in close proximity to the transmitter. The performance of each is evaluated. Efficient independent transmit and receive volume arrays can be constructed in this tight configuration. Tim Herrmann1, Johannes Mallow1, Jörg Stadler2, Zang-Hee Cho3, Kyoung-Nam Kim3, Johannes Bernarding1 1Department of Biometry and Medical Informatics, OvG University, Magdeburg, Saxony-Anhalt, Germany; 2Leibniz-Institute for Neurobiology, Magdeburg, Germany; 3Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea, Republic of Goal of this study was to expand the abilities in fMRI experiments. To reach this goal a CP Dual Helmholtz saddle Tx / 8–ch.-Rx head-coil for 7T whole body system was simulated and constructed. This RF-coil has even more potential for visual stimulation and acoustic fMRI. The field simulation software allowed us to optimize the positioning of the capacitors and the extension of the frontal space between the phased array coils to allow visual fMRI experiments. 15:30 3824. Eight-Channel Tx/Rx Helmet Coil for Human Brain Imaging with Improved RF Homogeneity Wolfgang Driesel1, Toralf Mildner1, André Pampel1, Harald E. Möller1 1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany Two versions of an anatomically shaped microstrip transmission-line (MTL) helmet coil were built: (A) a circularly polarized (CP) transmit/receive (Tx/Rx) coil and (B) a CP-Tx/eight-channel-Rx array. Curved MTL elements of different lengths were used to provide sufficient space for audiovisual stimulation and the electrical length was adjusted by proper termination. Both helmet coils generated an almost perfect circular polarization in a large portion of the human head extending into regions near the coil elements. Initial experiments verify that the designs permit imaging of the brain with good tissue contrast and potential for parallel imaging. Tuesday 13:30-15:30 Computer 45 13:30 3825. Tilted Transceiver Array for Ultra-High Field MRI Bing Wu1, Yong Pang1, Chunsheng Wang1, Daniel Vigneron1,2, Xiaoliang Zhang1,2 1Radiology&Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; 2UCSF/UC Berkeley Joint Group Program in Bioengineering, CA, United States Element-tilted transceiver array was proposed for ultra-high field human studies. An 8-channel microstrip and an 8-ch loop array were fabricated for human knee at 7T. In those arrays, each element was tilted with a certain angle for achieving sufficient decoupling without using dedicated decoupling networks. Our result showed that decoupling was significantly improved (better than –18dB) for both arrays, and the B1 field is also increased (better than 20%) in the imaging region for the microstrip array compared with non-tilted case. 14:00 3826. RF Transparent Array for Testing Multi-Channel Transmit Systems Katherine Lynn Moody1, Neal Anthony Hollingsworth2, Jon-Fredrik Nielsen3, Doug Noll3, Steven M. Wright, 1,2, Mary Preston McDougall1,2 1Biomedical Engineering, Texas A&M University, College Station, TX, United States; 2Electrical and Computer Engineering, Texas A&M University, College Station, TX, United States; 3Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States The use of high channel count transmit arrays in the clinical setting has yet to become widespread, and the integration of prototype hardware with a clinical scanner for testing adds complexity. A simple 8-channel transmit array capable of operating in series or parallel resonance was implemented to facilitate testing of multiple parallel transmit platforms, in particular comparing voltage and current source excitations schemes. The transmit array has been successfully implemented on a 3T GE clinical scanner and can simply be inserted into the body coil (used as the receive coil) without the need for a decoupling network. 14:30 3827. A Mechanically Tuned 8-Channel Microstrip Array for Parallel Transmission at 7T (297MHz) Benoit Schaller1, Arthur W. Magill1,2, Rolf Gruetter1,3 1Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 2Department of Radiology, University of Lausanne; 3Department of Radiology, Universities of Lausanne and Geneva, Switzerland We present a new 8-channel microstrip array desiged for RF shimming and parallel transmission. Strips, mechanically tuned by adjusting the height over the ground plane, are symmetrically fed via a lattice balun, making the probe tune and match invariant under different loading conditions (different subject). Tuning and matching capacitors are fixed, the array gives a match of better than -23dB with Q=37 (loaded). Coupling between nearest neighbors was -22dB (loaded), and -17dB for the next neighbors, obtained without decoupling capacitors between elements. MR scans showed a penetration of 65mm inside a cylindrical saline phantom (Ø160mm, L=360mm). 15:00 3828. Slot-Line Antenna Array for High Field Parallel Transmit MRI Christoph Leussler1, Daniel Wirtz1, Peter Vernickel1 1Philips Research Europe, Hamburg, Germany We demonstrate initial results on the development of slot-line Tx/Rx array antennas for MRI. While the coil elements of a conventional antenna array typically are of TEM- or loop-type, the slot-antenna is fundamentally different: it can be understood as the complementary structure to an electric dipole. According to Babinet’s principle, E- and B-fields are exchanged for both types of antennas. Slot antennas provide new degrees of freedom in antenna design: the operating frequency can be tuned geometrically (by adjusting the slot-size) or electrically by using (very few) resonance capacitors. Wednesday 13:30-15:30 Computer 45 Hoby Patrick Hetherington1, Nikolai I. Avdievich1, Jullie W. Pan1 1Neurosurgery, Yale University, New Haven, CT, United States Transceiver arrays using multiple RF coils and RF shimming have demonstrated improved performance in comparison to conventional volume coils at 7T in the human brain. However, the variability in performance of these arrays across a large group of subjects and brain locations has been questioned due to their strong interactions with the sample. In this work we describe an 8 element transceiver array with selectable geometry and inductive decoupling which simplifies tuning and matching and provides consistent performance with regards to power requirements and overall homogeneity. We report results from 82 subjects at 7T characterizing the performance of the coil. Rong Xue1, Huabin Zhu2, Haoli Ma1, Yanxia Li1, Yan Zhuo1 1State Key Lab. of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; 2RF Department, Siemens Mindit Magnetic Resonance Ltd, Shen Zhen, China We have successfully constructed a novel 8-channel phase-array transmit/receive head coil on Siemens 3T Tim Trio system for research on parallel transmission techniques including multiple-channel phase-array RF coil design and homogenous B1 shimming. The coil was better suited for Asian people fMRI studies, with an unblocked visual field as well as high image SNR and signal stability. The whole setup including the Tx/Rx coil, the related RF interface and parallel transmission techniques would further be applied to a Siemens 7T system and is expected to achieve good anatomical and functional images in ultra high field. Gregor Adriany1, Johannes Ritter1, Tommy Vaughan1, Kamil Ugurbil1, Pierre-Francois Van de Moortele1 1Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, MN, United States Efficient and homogeneous spin excitation in areas of the lower temporal lobe and the cerebellum is difficult to achieve at 7 tesla and above. We experimentally evaluated the performance of a 7 tesla transceiver head array with z encoding capability and compared this coil to a similar sized coil without the additional coil elements along the z direction. Capability to RF shim the whole head is demonstrated. 15:00 3832. 7 Tesla 16-Element TEM Tx Coil with Dedicated 14-Channel Receive-Only Array Tamer S. Ibrahim1, Tiejun Zhao2, Fernando E. Boada3 1Departments of Bioengineering and Radiology, Univeristy of Pittsburgh, Pittsburgh, PA, United States; 2Siemens Medical Solutions; 3Department of Radiology, University of Pittsburgh In this work we present a design for homogenous and efficient Tx head coil combined with receive-only array. The coil exhibits excellent homogeneity throughout the brain volume. In addition, the coil is also highly efficient and is capable of achieving 180o flip angle without SAR violation. Thursday 13:30-15:30 Computer 45 Yu Li1, Ewald Weber1, BingKeong Li1, Feng Liu1, Johannes Schneider2, Stéphanie Ohrel2, Sven Junge2, Peter Ullmann2, Markus Wick2, Stuart Crozier1 1School of ITEE, The University of Queensland, Brisbane, Queensland, Australia; 2Bruker BioSpin MRI GmbH, Ettlingen, Germany In this work, the development of an optimized, shielded 8-element transceive volume-array for small animal MRI applications at 9.4T is discussed. A novel stripline-like sandwiched conductor structure for the coil element has been proposed. A prototype was constructed and tested in a Bruker 9.4T Biospec MRI system. Simulated and experimental results presented herein demonstrate the potential of the design. 14:00 3834. A Novel TxRx Head Coil for Visual Stimulation FMRI with High Signal Stability Huabin Zhu1,2, Yanxia Li2, Bida Zhang3, Jianmin Wang1, Yan Zhuo2, Rong Xue2 1Radio Frequency Department, Siemens Mindit Magnetic Resonance Ltd., Shenzhen, Guangdong, China; 2State Key Lab. of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; 3Siemens Mindit Magnetic Resonance, Siemens Healthcare MR Collaboration NE Asia, Shenzhen, Guangdong, China A large portion of fMRI experiments include visual stimulation. An unblocked vision window can improve subject's coziness, and hence improve the reliability of visual stimulation experiment. Normally fMRI experiments demand high stability of MRI scanners including coil and other components, to ensure stable signal magnitude for temporal measurements. Using Siemens Trio Tim system and its 12-ch head coil, the signal fluctuation with a signal shot EPI sequence without stimulation can be about 0.4-0.5 percent on water phantom. In this project, we developed an 8-ch TxRx phase-array head coil , which has two obvious advantages in fMRI. First, a rectangular window of size 116mmx74mm is opened in the upper part of the coil to provide a comfortable vision view for subjects. Second, there is significant improvement in signal stability, which helps to detect the small signal change during fMRI scanning. Stephan Orzada1,2, Stefan Maderwald1,2, Sophia L. Göricke2, Nina Parohl2, Susanne C. Ladd1,2, Mark E. Ladd1,2, Harald H. Quick1,3 1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, NRW, Germany; 2Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, NRW, Germany; 3Institute of Medical Physics, Friedrich-Alexander-University Erlangen-Nurnberg, Erlangen, Germany MRI of rodents is an ever growing application when translatory imaging research “from mouse to man” is envisioned. In this study, two different multi-channel transmit/receive radiofrequency coil arrays have been designed for high-resolution rodent imaging on a 7T whole-body human MRI system. Both arrays have been evaluated in comparative phantom experiments and in vivo high-resolution MRI in rats. Both coil setups provided high signal-to-noise-ratio in rodents. While the 8-channel loop radiofrequency array with its larger inner diameter provided better overall signal homogeneity, the 8-channel novel stripline radiofrequency array design provided overall higher signal-to-noise-ratio and better parallel imaging acceleration performance. 15:00 3836. A 3.0-Tesla Transmit and 32-Channel Receive Head Array Coil Tsinghua Zheng1, Craig Lawrie1, Xiaoyu Yang1, Joseph Herczak1, Paul Taylor1, Hiroyuki Fujita1,2, Takahiro Ishihara3, Kazuya Okamoto3, Sadanori Tomiha3, Kaori Togashi4, Tomohisa Okada4 1Quality Electrodynamics, LLC, Mayfield Village, OH, United States; 2Departments of Physics and Radiology, Case Western Reserve University, Cleveland, OH, United States; 3Toshiba Medical Systems Corporation, Otawara, Tochigi, Japan; 4Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan We have developed a 3-Tesla head array with an integrated local birdcage transmit coil and 32-receive surface coils for much higher spatial and temporal resolution head imaging. The coil was tested on a Toshiba 3T Atlas 32-Channel MRI System. Benchmarking with a commercially-available 1.5-Tesla 14-channel receive-only head array coil, the proposed Tx-and-32Rx head coil showed a significant improvement in image quality with respect to the SNR enhancement and much improved temporal resolution that are well expected from a higher channel count array coil. Hall B Monday 14:00-16:00 Computer 46 14:00 3837. 1H/23Na Dual-Tuned RF Unicoil for Human Body MR Imaging at 3T - not available Jung-Hwan Kim1, Kyung-Nam Kim2, Chan Hong Moon1, Suk-Min Hong2, Bum-Woo Park1, Haekyun Joshua Park2, Kyongtae Ty Bae1 1University of Pittsburgh, Pittsburgh, PA, United States; 2Gachon University of Medicine and Science, Incheon, Korea, Republic of We have developed a dual-tuned 1H and 23Na coil at 3T by utilizing the Unicoil concept and coil geometry to improve the SNR and RF penetration depth. The coil allowed us to acquire 1H and 23Na images of the spine and kidney with excellent image quality. Future studies include development and generalization of Unicoil concept for imaging other body parts and comparative evaluation of the performance of Unicoil with other coil designs. 14:30 3838. A Flexible 32-Channel Array for 3He Human Lung Imaging at 1.5T Martin H. Deppe1, Juan Parra-Robles1, Titus Lanz2, Jim M. Wild1 1Academic Radiology, University of Sheffield, Sheffield, Yorkshire, United Kingdom; 2Rapid Biomedical GmbH, Rimpar, Germany This work presents a flexible 32-channel array coil for imaging of hyperpolarized 3He at 1.5 T, designed as an insert into an existing birdcage transmit coil of excellent B1 homogeneity. The array consists of an anterior and a posterior half, containing 16 channels each. Nearest neighbours are decoupled by concentric shields. Functionality of the array is demonstrated by human lung images at different acceleration factors. Residual coupling to the transmit coil, which is currently not detuned during the reception phase, remains, and will be addressed in future by detuning the birdcage. 15:00 3839. 28-Channel Receive-Only Array for Body Imaging at 7T Carl J. Snyder1, Lance DelaBarre1, Jinfeng Tian1, Can Akgun1, Gregory John Metzger1, Kamil Ugurbil1, J. Thomas Vaughan1 1University of Minnesota, Minneapolis, MN, United States Currently most 7T body imaging is limited to surface transeive arrays. However, dedicated transmit coils used in combination with local receive-only arrays have shown benefits at lower field strengths. Here we have constructed a 28-channel receiver array to be used with a dedicated transmit array at 7T. 15:30 3840. ASK-Asymmetric Saddle K-Topology for Spinal Cord Imaging Modhurin Banerjee Snyder1, Pei H. Chan1, Fraser Robb1 1GE Healthcare, Aurora, OH, United States A coil system based exclusively on the Double Asymmetric Saddle Pair motif was conceived as an extension of the work done with the DLAS (Double Loop Asymmetric Saddle) system. This coil system, dubbed the ASK (Asymmetric Saddle K-topology) was evaluated for SNR and uniformity-of-response performance against loop-based, quadrature loop/saddle-based, and DLAS based designs via phantom imaging. The relative SNR gain provided by the ASK array compared to the DLAS ranges from 40 % at the periphery to 15% at the center; furthermore, the ASK system demonstrated a peak SNR (at center) 20% better than the standard Quadrature Coil(QD). Tuesday 13:30-15:30 Computer 46 Quinn Tate1, Laura C. Bell2, Seong-Eun Kim2, Emilee Minalga2, Dennis L. Parker2, J. Rock Hadley2 1Radiology-UCAIR, University of Utah, Salt Lake City, UT, United States; 2Radiology - UCAIR, University of Utah, Salt Lake City, UT, United States A 16 channel recieve only coil was constructed in order to meet the need for greater relative signal to noise ratio (rSNR) at the carotid bifurcation as well as increased coverage of the anatomy, and improved parallel imaging performance. Current 4 channel coils provide acceptable rSNR. However, the 4 channel coil has a limited field of view which can require repositioning. The 16 channel coil increases the S/I FOV while significantly increasing the rSNR along the vessel compared to the 4 channel coil. This coil also enables Reduction factors of R=2 and 3, reducing possible image artifacts from motion 14:00 3842. QASCI-Quadruple Asymmetric Saddles for Cardiac Imaging Modhurin Banerjee Snyder1, Pei H. Chan1, Fraser Robb1 1GE Healthcare, Aurora, OH, United States In this work we have created a flexible, modular 32-channel array for cardio-thoracic imaging that is based on traditional loop elements and Double Asymmetric Saddle (DAS) pairs. This unique design, dubbed the QASCI (Quad Asymmetric Saddle for Cardiac Imaging), is an extension of the work done with the DLAS (Double Loop Asymmetric Saddle) to a cardiothoracic application. The QASCI system was evaluated via phantom imaging, and demonstrated a nominal 50% improvement in SNR over a larger FOV (34cm by 34 cm) than the 8 channel cardiac coil, even when evaluated on an element-by-element/channel-by-channel basis. 14:30 3843. An Optimized “QD-Like” 6-Channel Flexible and Ergonomic Shoulder Array Coil at 1.5T Xiaoyu Yang1, Steven Walk1, Paul Taylor1, Tsinghua Zheng1, Hiroyuki Fujita1,2 1Quality Electrodynamics, Mayfield Village, OH, United States; 2Physics and Radiology, Case Western Reserve University, Cleveland, OH, United States The MRI trend sees the increasing availability of wider-bore scanners at 1.5T and 3T to accommodate much broader coverage of the patient population. Addressing the need, an optimized 6-channel ergonomically-designed shoulder coil is proposed at 1.5T. The coil consists of 3 rows of loop and saddle pairs with flexible flaps for better fitting of different size shoulder sizes and thereby increasing SNR. Comparison tests were performed between the proposed flexible coil and a commercially available 4-channel rigid shoulder coil. The testing and evaluation also included the performance comparison among various shoulder sizes. The results show that the proposed “one-fits-all” coil provides good SNR, depth coverage and uniformity for the broad range patient population. 15:00 3844. A 8+4-Channel Receive Phased Array for Imaging Newborns and Premature Infants at 1.5T Stefan Fischer1, Florian M. Meise2, Jörn Ewald2, Torsten Hertz2, Torsten Lönneker-Lammers3, Laura M. Schreiber1 1Department of Diagnostic and Interventional Radiology, Section of Medical Physics, University Medical Center of the Johannes Gutenberg-University, Mainz, RLP, Germany; 2LMT Medical Systems GmbH, Lübeck, SH, Germany; 3Lammers Medical Technology GmbH, Lübeck, SH, Germany In this study a 8+4-channel receive phased array for optimized MRI of newborns and premature infants at 1.5T was developed. State of the art MRI coils are mostly designed for adults and suitable to only a limited extent for pediatric and newborn imaging. Several challenges like imaging of small objects with high resolution and accelerated imaging to prevent motion artifacts can be met by using an adapted phased array. It provides high signal-to-noise-ratio and the possibility for accelerated imaging. The very compact design allows using the 8+4-channel array system in a MR safe incubator to minimize environmental stress. Wednesday 13:30-15:30 Computer 46 13:30 3845. Multi-Coil MR Imaging with a Receive Array of Eight Microcoils Kai Kratt1, Elmar Fischer2, Vlad Badilita1, Mohammad Mohammadzadeh2, Jürgen Hennig2, Jan G. Korvink1,3, Ulrike Wallrabe1,3 1Dept. of Microsystems Engineering - IMTEK, University of Freiburg, Freiburg, Germany; 2Dept. of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany; 3Freiburg Institute of Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany We present the development of an eight-channel microcoil array as a prototype for the simultaneous detection of signal from samples at predefined spatial positions. The manufacturing process is fully MEMS compatible, therefore being cost-effective and making the array suitable for one-time usage. Eight microcoils have been selected for this study, but the number of coils (i.e. positions) could be extended to the maximum number of receive channels provided by the MRI spectrometer. By varying size, number and mutual distance of the microcoils, such a multi-coil array can be used for testing detection schemes of parallel imaging techniques. 14:00 3846. Modular, Decoupled Yet Bendable Coil Array System at 3T Stefan Schonhardt1, Andreas Peter2, Jan G. Korvink2,3 1Department of Microsystems Engineering, University of Freiburg - IMTEK, Freiburg, Germany; 2Department of Microsystems Engineering, University of Freiburg - IMTEK, Germany; 3Freiburg Institute of Advanced Studies (FRIAS), University of Freiburg - IMTEK, Freiburg, Germany A hexagonal surface filling coil tiling has been designed and manufactured in a flexible Polyimide foil, featuring additional overlap loops on all six tips of a hexagon. The loops serve the purpose of decoupling the next neighboring coils. The immediate neighbor coils are decoupled by overlaps along their edges. The single identical coils are staggered with respect to each other to form an almost arbitrary large phased array. The respective coupling between the single coils is -20 dB or better, even if bent at a radius of 15 cm along an arbitrary in-plane direction. Nelly A. Volland1, Thomas H. Mareci2,3, Nicholas E. Simpson4 1Radiology, University of Utah, Salt Lake City, UT, United States; 2Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States; 3McKnight Brain Institute, University of Florida, Gainesville, FL, United States; 4Medicine, University of Florida, Gainesville, FL, United States Introduction: Uniform excitation and highly sensitive signal detection is necessary for optimal MRS of bioartificial constructs, particularly when determining function. Methods: Receive-only implantable coils were constructed, coated, and integrated with the macroconstruct. This assembly was inductively-coupled to an external coil and tested in vitro in combination with a transmit-only volume coil at 11.1T. Results: Studies showed small overall gains in SNR with this system under loaded conditions over a transmit-receive system, and greater signal uniformity. Conclusion: A receive-only implantable coil system was successfully built and tested. This system will allow for superior quantitative monitoring of implanted bioartificial organs. Hunter R. Underhill1,2, Chun Yuan1, Cecil E. Hayes1 1Radiology, University of Washington, Seattle, WA, United States; 2Bioengineering, University of Washington, Seattle, WA, United States In this study, a novel coil design, subsequently referred to as the rat brain coil, is described which exploits and combines the strengths of both solenoids and surface coils into a simple, multi-channel, receive-only coil dedicated to whole-brain rat imaging on a 3.0 T clinical MR scanner. Compared to other coils, the rat brain coil improved SNR by a minimum of 60%. Improvement in SNR afforded by the rat brain coil may broaden applications and experiments that utilize clinical MR scanners for in vivo image acquisition. Thursday 13:30-15:30 Computer 46 13:30 3849. Enhancing FMRI Sensitivity at 7T with a Modular 16-Channel Small Element Surface Coil Natalia Petridou1, M Italiaander1, B.L. van de Bank1, J.C.W. Siero1, J.M. Hoogduin1, P.R. Luijten1, D.W.J. Klomp1 1UMC Utrecht, Utrecht, Netherlands Even though the BOLD contrast is enhanced at 7T, the finer scale of neurovascular coupling remains difficult to detect because the high spatial and temporal resolution required to explore these properties remain limited by SNR. To improve SNR we developed a 16channel surface coil comprised of 1x2cm elements arranged in 4 flexible modules that can be positioned within 1mm from the human head; we show that a surface array consisting of the theoretical smallest useful element dimension enhances SNR at 7T. This surface array can be used with high resolution fMRI to improve sensitivity as compared to conventional receiver arrays. Stephan Orzada1,2, Oliver Kraff1,2, Kasja Rabe3, Dagmar Timman-Braun3, Mark E. Ladd1,2 1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, NRW, Germany; 2Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, NRW, Germany; 3Department of Neurology, University Hospital Essen, Essen, NRW, Germany In this work we present a 7-channel receive coil which can be inserted into a non-detunable commercially available 8 channel head coil for 7 T. The insert is used to enhance image quality and imaging speed in the cerebellum and in the visual cortex. Image comparisons show that image quality is improved even at higher parallel imaging acceleration factors. 14:30 3851. Improved Optic Nerve Imaging Using a Collapsible Head Coil Design Robb Merrill1, Dennis Parker1, Emilee Minalga1, Laura Bell1, John Rose2,3, Rock Hadley1 1Dept. of Radiology (UCAIR), Salt Lake City, UT, United States; 2Neurovirology Laboratory VASLCHCS; 3Brain Institute Existing head coils are typically built using one-piece rigid cylindrical formers. The performance of advanced imaging techniques of the optic nerve is limited by reduced SNR when smaller-sized heads are imaged in these coils. Phantom studies in a rigid 12-channel Siemens coil indicate an SNR difference of over 60% when the coil-to-sample distance from the top coil elements is decreased by 4cm. This study shows results from an improved collapsible-design head coil specifically built for optic nerve imaging. Volunteer studies show an SNR improvement of nearly 30% in the orbits when the collapsible optic nerve coil is used. 15:00 3852. A Multi-Element Receive Coil Array for MRI/FMRI of Awake Behaving Marmosets Hellmut Merkle1, Julie B. Mackel1, Junjie V. Liu1, Yoshiyuki Hirano1, Afonso C. Silva1 1NINDS, NIH, Bethesda, MD, United States Significant effort has been placed on the development of awake behaving animals that allow longitudinal studies to be carried out without the confounds of anesthesia. Here we describe a 7-element receive coil array for MRI/FMRI scanning of awake behaving marmosets at 7 Tesla incorporated into individualized noninvasive helmet restraints and integrated to low input impedance RF preamplifiers. Excellent isolation between the coils and spatial coverage of the whole brain were achieved. The SNR was optimized to the somatosensory and motor cortices. Further refinements of the helmet restraint will lead to additional geometries optimized for different brain regions. Measuring & Modeling RF Performance Hall B Monday 14:00-16:00 Computer 47 14:00 3853. Accurate Measurement of RF Power Deposition During 3T MRI - not available AbdElMonem M. El-Sharkawy1, Di Qian, 1,2, Paul A. Bottomley1,2, William A. Edelstein1 1Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, United States; 2Electrical and Computer Enginnering, Johns Hopkins University, Baltimore, MD, United States Accurate measurements of RF power deposition are central to safe MRI operation, especially at higher fields. We have characterized the losses in the body coil, cables, filter box, transmit-switch and quadrature hybrid. We find that transmit chain and body coil losses are such that the power reaching the patient is < 50% of the power supplied by the transmitter. Measured power deposition in four subjects of different body mass indices varied from 46-83% of the scanner estimated power deposition. This indicates that scanner estimates are not accurate indicators of MRI RF exposure. Shumin Wang1, Jacco A. de Zwart, Jeff H. Duyn1 1LFMI/NINDS/NIH, Bethesda, Center Dr. , United States The performance of high-field receive coil arrays depends on the geometry of coil elements, the shape of subjects, and their relative position. Knowing the actual performance, such as the combined sensitivity and the g-Factor maps, is valuable in post-processing images. Conventionally, subject-specific coil performance was evaluated via measurements. In this work, we present an alternative approach by numerical simulations based on fast integral-equation method and subject models obtained from MRI pre-scans. Results demonstrate the feasibly of performing subject-specific coil evaluations based on pure numerical approaches. 15:00 3855. RF-Invisible Inductors Victor Taracila1, Vijayanand Alagappan1, Aleksey Zemskov1, Fraser Robb1 1GE Healthcare, Aurora, OH, United States Ideal inductors must have lump circuit characteristics only, without exhibiting any radiative properties. These goals might appear to be contradictory since inductors with higher inductances must be bigger and have a certain surrounding volume for magnetic field confinement. In this work we address the question of the “invisible” inductors – inductors with highly confined magnetic field, which still have satisfactory inductive characteristics. 15:30 3856. Detailed Investigations of a Metamaterial Transmit/receive Coil Element for 7 T MRI Jochen Mosig1, Achim Bahr1, Thomas Bolz1, Andreas Bitz2, Stephan Orzada2 1RF&Dosimetry, IMST GmbH, Kamp-Lintfort, Nordrhein-Westfalen, Germany; 2Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Nordrhein-Westfalen, Germany In a previous work the design and numerical results for a composite right/left-handed metamaterial coil element were presented. This work shows dosimetric measurement and first imaging results together with further numerical results. A good agreement between the simulations and the measurements was observed. In contrast to the homogeneous B1 field, the circular polarized B1+ field shows some discontinuities. This has lead to the investigation of different designs for the metamaterial element. As a result, an extended layout is presented, that eliminates the local minima in the field distribution of the original element, and shows a significant different field distribution. Tuesday 13:30-15:30 Computer 47 Yu Li1, Feng Liu1, Jin Jin1, Ewald Weber1, BingKeong Li1, Hua Wang1, Stuart Crozier1 1The University of Queensland, Brisbane, Queensland, Australia Because of the specific position of a patients’ breast related to the B0 field of a horizontal clinical MRI scanner, it is challenging to use conventional equal structured loop coils to induce a desired homogenous B1 field. More importantly, in the anterior-posterior area of the breast, little or no signal can be received by a loop coil. This work presented a loop-strip hybrid transceive phased array breast coil design. The new design can offer improvement to the B1 field in the anterior-posterior area of the breast, which is difficult to achieve by using a loop-only breast coil. 14:00 3858. A Comprehensive Coil Resistance Composition Model for High Field Qi Duan1, Daniel K. Sodickson1, Bei Zhang1, Graham C. Wiggins1 1Center for Biomedical Imaging, Department of Radiology, NYU School of Medicine, New York, NY, United States This abstract provides a detailed understanding for loop coil resistance, a crucial component of SNR in the MR experiment. In comparison to existing models, the new model presented in this abstract includes more components which were often overlooked in the past and thus yields more realistic prediction of coil resistance at high field. The ability to characterize coil losses is the key for optimizing loop-based coil and array designs, and providing an accurate coil noise model in full-wave simulations. 14:30 3859. Statistical Noise Model in GRAPPA-Reconstructed Images Santiago Aja-Fernandez1, Antonio Tristan-Vega1, Scott Hoge2 1Universidad de Valladolid, Valladolid, VA, Spain; 2Brigham and Women's Hospital, Boston, MA, United States A statistical noise model is derived for multiple-coil MR signals when using subsampling and GRAPPA reconstruction methods. The reconstructed data in each coil is shown to follow a non-stationary Gaussian distribution. Under some assumptions the signal may be considered as nearly stationary. For each pixel, if the coefficient of variation of the noise variance across coils is low enough, a non-central Chi model may be considered. This is the same model used for non-subsampled multiple-coil acquisitions. However, the non-central Chi model is not always assured in GRAPPA reconstructed data. 15:00 3860. Channel Reduction with Multiple Receptions Bing Wu1, Chunsheng Wang1, Yong Pang1, Xiaoliang Zhang1,2 1Radiology&Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; 2UCSF/UC Berkeley Joint Group Program in Bioengineering, CA, United States The need for high signal-to-noise ratio and fast imaging acquisitions have driven the development of MRI systems with more receive channels. However, such multi-channel systems are not always available. Array compression techniques with the use of hybrids, Butler matrix or mode-mixing hardware, allow the optimal use of existing channels. In this work, a straight-forward method by applying multiple receptions is proposed for channel reduction. Wednesday 13:30-15:30 Computer 47 13:30 3861. MR Simulation System for MR Guided Radiation Therapy at 3.0T Haoqin Zhu1, Mehran Fallah-Rad1, Alexander Shvartsberg1, Victoria Hornblower1, Labros Petropoulos1 1IMRIS Inc, Winnipeg, MB, Canada Until recently, MRI has only been used as a guidance tool during Radiation Therapy’s planning stage, due to CT’s inability to image oblique planes and large FOVs. Presently, there are no MR compatible simulation systems incorporating the head-neck mask and obtaining MR images for Radiation Therapy planning. We propose, a novel MR simulation system for RT planning of head-neck tumors that includes an MR compatible board combined with a dedicated set of three phased array coils, providing superior uniform coverage of the head-neck region with minimum 40% SNR increase when compared to a commercially available coil system. Ye Li1, Yan Guo1, Xiaohua Jiang1 1Department of Electrical Engineering, Tsinghua University, Beijing, China This work proposes an approach to analysis the equivalent noise resistance, including coil self-resistance, of surface coils of low field MRI and small volume coils of extra high field MRI using the finite element method. The simulation and imaging results suggest that the finite element method is feasible to analyze surface coils of low field MRI and small volume coils of extra high field MRI. The coil self-resistance accounts higher percentages of the equivalent noise resistance of surface coil whereas it is comparable with the sample resistance of animal coils which are integrated with animal holder. Wouter Teeuwisse1, Christopher Collins2, Ching Wang2, Qing Yang2, William Ma2, Nadine Smith1, Matthias van Osch1, Andrew Webb1 1Radiology, Leiden University Medical Center, Leiden, Netherlands; 2Radiology, Hershey Medical School, Hershey, PA, United States Although pulsed arterial spin labelling should benefit from high fields in terms of sensitivity and longer blood T1 values, there are significant challenges to its successful implementation. One of the major difficulties is in using commercial volume transmit coils for efficient arterial labelling due to the inherent B1 inhomogeneities produced by a human subject at high field. This work presents a simulation study, and confirmatory experimental results, which show that the use of appropriately-positioned water-based dielectric pads can be used to increase the labelling efficiency and improve the quality of ASL scans at 7 Tesla. 15:00 3864. Quantitative Calculation of the Proton Radiation Damping Constant at 14.1 Tesla James Tropp1, Kayvan Keshari2, Mark Van Criekinge 1Global Applied Science Lab, GE Healthcare Technologies, Fremont, CA, United States; 2Radiology, University of California San Francisco, San Francisco, CA, United States We have calculated the radiation damping constant for protons in neat H2O at 14.1 tesla, and confirmed the accuracy of our prediction by measurement. The calculation contains no adjustable parameters, and replaces the coil filling factor and Q with the coil efficiency, i.e. B1 per absorbed power. The calculated and measured linewidths are, respectively 46.6 Hz and 44.0 Hz. Thursday 13:30-15:30 Computer 47 13:30 3865. Simulation of a Novel Radio Frequency Ablation Device Within a MR Scanner Yik-Kiong Hue1, Jerome L. Ackerman1 1Martinos Center, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States An electromagnetic modeling of a novel radiofrequency ablation device within the MR scanner was done to study the safety and performance issue. It provides quantitative and understandable model of the physics in rough agreement with the experiment. 14:00 3866. Numerical Investigation of Nonlinear, Spatially-Varying Pulsed Magnetic Fields Tony Stöcker1, Kaveh Vahedipour1, N. Jon Shah1,2 1Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich, Juelich, Germany; 2Faculty of Medicine, RWTH Aachen, Aachen, Germany Curved spatially-varying magnetic fields have a strong impact on MRI, especially in the context of correcting magnetic field inhomogeneities (shimming). New progress from hardware and sequence development intends to overcome certain limitations, e.g. by the use of higher-order shim coils or the application of spatially-selective dynamic shimming. Beyond field corrections, curved field gradients are also under discussion for region-specific zoomed spatial encoding with reduced peripheral nerve stimulations. However, the gains from such strategies are hardly predictable without simulations. Here, a framework for exact numerical MRI simulations of nonlinear spatially-varying pulsed magnetic fields is presented. 14:30 3867. Modelling the Sources of the Pulse Artefact in Simultaneous EEG/fMRI Winston X. Yan1, Karen Julia Mullinger1, Gerda B. Geirsdottir1, Richard W. Bowtell1 1Sir Peter Mansfield Magnetic Resonance Center, School of Physics and Astronomy, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom Simultaneous EEG/fMRI is hindered by large artefacts in EEG recordings. The pulse artefact (PA) is particularly troublesome because of its variability and persistence after artefact correction. We investigate two potential causes of the PA (cardiac-pulse-induced head rotation and Hall voltages generated by blood flow), through physical modelling and experimental measurements on an agar phantom and human head. Our results show head rotation is the most plausible artefact source, generating artefact patterns and magnitudes similar to the measured PA for realistic motional parameters. The models derived here can facilitate development of improved artefact correction algorithms based on simulated spatial templates. 15:00 3868. Measurement of Q-Factors Including Radiation Loading of Strip-Type Coils for 7-Tesla MRI Klaus Solbach1, Stephan Orzada2, Pedram Yazdanbakhsh1 1Radio Frequency Technology, University Duisburg-Essen, Duisburg, Germany; 2University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany Our strip conductor-type coil for 7-Tesla MRI exhibits strong radiation loading due to its length of a quarter-wave. The loading by a phantom is seen to be superimposed by mutual coupling effects in a similar way as known from antennas. When using the conventional figure of merit based on the “unloaded” to “loaded” Q-factors we have to perform the “unloaded” measurement with the coil under a conducting shield (”Wheeler cap”) in order to exclude the radiation loading. Hall B Monday 14:00-16:00 Computer 48 14:00 3869. Local SAR Calibration and Prediction Model in Parallel Transmit MRI Leeor Alon1, Cem Murat Deniz1, Riccardo Lattanzi1, Graham Wiggins1, Ryan Brown1, Daniel K. Sodickson1,2, Yudong Zhu1 1Center for Biomedical Imaging, Department of Radiology, NYU School of Medicine, NYU School of Medicine, New York, NY, United States; 2Sackler Institute of Graduate Biomedical Sciences, NYU School of Medicine, New York, NY Current SAR monitoring methods offer no capability for a-priori prediction of local SAR under actual experimental conditions. In this study, we present a model implementation for the calibration and prediction of local SAR distribution in parallel transmit MR systems. Calibration based on a modest number of targeted MR thermometry experiments suffices to enable accurate prediction of local SAR maps for any pulse shape in situ as long as the temperature change is within linear regime and heating occurs rapidly. This method is a potential candidate for ex-vivo local SAR prediction, which would be useful to evaluate the performance of parallel transmit coil setups on various tissues with different electrical properties. In vivo applications will also be explored. Martijn Anton Cloos1, Michel Luong2, Guillaume Ferrand2, Alexis Amadon1, Dennis Le Bihan1, Nicolas Boulant1 1CEA, DSV, I2BM, NeuroSpin, LRMN, Gif-sur-Yvette, France; 2CEA, DSM, IRFU, SACM, Gif-sur-Yvette, France When using parallel transmission at high field, it is well established that high local specific absorption rate (SAR) values can occur. So far, no reports have been made regarding the behavior of transmit-SENSE pulses with regard to amplitude and phase perturbations. In this work, we investigated the behavior of the local SAR regarding perturbed spoke k-space trajectory-based excitation pulses designed using simulated B1-maps. Results indicate that although substantial variations can occur the local SAR may be considered relatively robust and remains far below the local SAR obtained with the worst-case scenario. 15:00 3871. Specific Absorption Rate Monitor for In-Vivo Parallel Transmission at 7 Tesla Martijn Anton Cloos1, Nicolas Boulant1, Michel Luong2, Guillaume Ferrand2, Dennis Le Bihan1, Alexis Amadon1 1CEA, DSV, I2BM, NeuroSpin, LRMN, Gif-sur-Yvette, France; 2CEA, DSM, IRFU, SACM, Gif-sur-Yvette, France It is well established that high local specific absorption rate (SAR) values can occur when using a transmit array at high field. In order to guarantee patient safety without harsh limitations to in-vivo transmit-SENSE applications, subtle SAR monitoring is necessary. In this work we present a SAR monitor at 7 Tesla based on real-time measurement of power going out of each RF amplifier in combination with pre-calculated simulations over a variety of human head models and positions. 15:30 3872. SAR Monitoring and Pulse Design Workflow in Parallel Transmission at 7 Tesla Khaldoun Makhoul1, Yik-Kiong Hue1, Lohith Kini2, Kawin Setsompop1, Joonsung Lee2, Kyoko Fujimoto1, Elfar Adalsteinsson2,3, Lawrence Leroy Wald1,3 1A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, United States; 2Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States; 3Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States The use of parallel transmission requires additional care to avoid exceeding local SAR limits. SAR calculation must be done for each RF pulse designed while the subject is in the scanner. An integrated software tool for SAR monitoring provides a means of performing B1+ mapping, RF pulse design and SAR checking in a simple workflow, emphasizing patient safety. Using pre-calculated E1 fields, and performing the SAR calculation on a consumer-level graphics processor, computation times on the order of minutes are achieved. Tuesday 13:30-15:30 Computer 48 13:30 3873. Towards Patient-Specific SAR Calculation for Parallel Transmission Systems Ingmar Graesslin1, Shumin Wang2, Sven Biederer3, Giel Mens4, Bjoern Annighoefer5, Hanno Homann1, Jeff Duyn2, Paul Harvey4 1Philips Research Europe, Hamburg, Germany; 2NINDS, National Institutes of Health, Bethesda, MD, United States; 3Institute of Medical Engineering, University of Lübeck, Lübeck, Germany; 4Philips Healthcare, Best, Netherlands; 5TU Hamburg-Harburg, Hamburg, Germany In parallel transmission, safety assessment via the specific absorption rate (SAR) is non-trivial, since local SAR distributions depend on the individual patient anatomy and on the multi-channel excitation. In general, patient safety can be achieved by carrying out simulation-based SAR calculations and by monitoring the deviation from the desired waveform. Typically, SAR calculations rely on generic patient models and on evaluation of worst-case scenarios. Patient-specific SAR calculations allow a more efficient exploitation of the respective limits and can improve imaging performance. This paper presents the general concept of patient-specific SAR calculations and describes the implementation of the real-time SAR computation. 14:00 3874. Patient-Specific SAR Models and in Vivo Validation Hanno Homann1, Ingmar Graesslin2, Holger Eggers2, Kay Nehrke2, Peter Börnert2, Olaf Dössel1 1Karlsruhe University, Karlsruhe, Germany; 2Philips Research, Hamburg, Germany Dielectric body models are increasingly used for safety assessment of the local specific absorption rate (SAR). In this work, a new method for the generation of dielectric body models from MR images was developed. The method is based on a water-fat-separation of MR images and an expectation-maximization (EM) segmentation of the 2D histogram. Models of five subjects in different body poses were generated and simulated using the finite-differences time-domain (FDTD) method. Validation of the simulated fields against measured B1 field maps was performed. 14:30 3875. Effects of Head Size and Position on SAR Mikhail Kozlov1, Robert Turner 1Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Sachsen, Germany We investigated effects of head size and position on SAR for a commercially available Rapid BioMed 7 T 8-element head coil. For this coil axial rotation of the head can be considered safe, if the distance to lumped capacitors is more than 20 mm. It is more dangerous to use this coil with the head only partly inserted. The total head SAR should be considered as the important safety limit, because the 3.2 W/kg whole head SAR limit is reached sooner than the 10W/kg local SAR limit. 15:00 3876. Patient-Specific in Vivo Local SAR Estimation and Validation Tobias Voigt1, Hanno Homann1, Ulrich Katscher2, Olaf Doessel1 1Institute of Biomedical Engineering, University of Karlsruhe, Karlsruhe, Germany; 2Philips Research Europe, Hamburg, Germany Local Specific Absorption Rate (SAR) is a major problem for high field MRI, particularly when using multiple transmit channels. In this study, a patient-specific estimation of local SAR based on B1 mapping is presented. Experimental results imaging healthy volunteers are validated using subject-specific FDTD simulations. It is found, that the presented approach yields a sufficiently accurate and patient-specific local SAR measurement. Wednesday 13:30-15:30 Computer 48 13:30 3877. RF Exposure and Resulting Temperature in the Fetus During MRI Jeff W. Hand1, Yan Li1, Jo V. Hajnal1 1Imaging Sciences Dept, Clinical Sciences Centre, Imperial College London, London W12 0NN, United Kingdom SAR and temperature in a 26 week pregnant woman within a 64 MHz birdcage coil are predicted numerically. Heat transfer from fetus to placenta via the umbilical vein and arteries as well as that across the fetal skin/amniotic fluid /uterine wall boundaries is modelled. Fetal SAR and average temperature comply with international limits when maternal whole body SAR ≤2 W kg-1, although maximum fetal temperature > 38oC may result from continuous exposure over periods ≥7.5 minutes. However, assessment of risk posed by the maximum temperature predicted in a static model is difficult in view of frequent fetal movement. 14:00 3878. SAR Evaluation of Whole-Body Pregnant Woman Models at Different Gestational Stage and Position in MRI Birdcage Coil Zhangwei Wang1, Desmond Yeo2, George Xu3, Jason Jin1, Fraser J. Robb1 1GE Heathcare Coils, Aurora, OH, United States; 2GE Global Research, Niskayuna, NY, United States; 3Rensselaer Polytechnic Institute, Troy, NY, United States A set of high-resolution whole body pregnant woman models at three gestational stages(3, 6 and 9 months) was adopted to investigate the SAR distribution at different position and field strength. The highest SAR is occurred in the mother's peripheral tissues in all pregnancy phase. And the maximum local SAR of the fetus is over IEC limitation in some cases. The results show that the local maximum SAR1g and SAR10g can be better indications as limitation factor other than the whole body average SAR Xin Chen1, Yoshinori Hamamura1, Michael Steckner1 1Toshiba Medical Research Institute USA, Inc., Mayfield Village, OH, United States Previous studies have shown that local SAR levels (hotspots) are much higher than whole body average SAR with a whole body transmit coil. Local SAR hotspots depend on many factors such as tissue heterogeneity, body habitus, and patient imaging position. This abstract extends previous 3T whole body SAR simulations with chest and abdomen imaging positions to five other common positions. Results show that 1) the SAR distribution varies significantly between imaging positions, and 2) the ratios of local SAR hotspot to whole body average SAR can be over 4x higher than previously reported. While temperature increase is the key safety concern, understanding SAR distribution is an important factor in patient safety. 15:00 3880. SAR Comparison for Multiple Human Body Models at 1.5T and 3.0T Zhangwei Wang1, Desmond Yeo2, Christopher M. Collins3, Jason Jin1, Fraser J. Robb1 1GE Heathcare Coils, Aurora, OH, United States; 2GE Global Research, Niskayuna, NY, United States; 3The Pennsylvania State University, Hershey, PA, United States High-resolution heterogeneous human body models are used increasingly in field calculations for MRI engineering and safety assurance. In this study, we modified six currently available male and female models and adapt to commercial finite-difference time-domain software. Calculations show that the human body shape and position have big effect on SAR distribution. Thursday 13:30-15:30 Computer 48 Sukhoon Oh1, Colin A. Roopnariane2, Mohammad-Reza Tofighi2, Christopher M. Collins1 1PSU College of Medicine, Hershey, PA, United States; 2Engineering and Technology, Penn State University, Middletown, PA, United States For evaluation of techniques for measuring heating related to specific absorption rate (SAR) in MRI, these can be advantageous to having independent control of heating and measurement coils. We describe an MRI-based method for mapping temperature and SAR using a solenoid coil and a birdcage coil for heating and imaging, respectively. The accuracy and quality of SAR/temperature mapping are enhanced by separating the heating and imaging coils. The MR-based temperature measurements were in good agreement with fiber-optic measurements. The dual-coil heating system was simulated using the finite-difference time-domain method. The distribution of numerically-calculated and experimentally-acquired SAR were in good agreement. 14:00 3882. Influence of Non-Conductive Probes on Specific Absorption Rate Sukhoon Oh1, Christopher M. Collins1 1PSU College of Medicine, Hershey, PA, United States Recently, there are an increasing number of interventional studies in which minimally invasive procedures are performed using MRI guidance using thin and precisely controlled devices and sensors. The influence of non-conductive devices on the specific absorption rate (SAR) in surrounding tissues are rarely investigated compared to studies investigating safety issues of metallic probes and devices. Here, we show that even non-conductive probes, in our case fiber optic thermal sensors, can have notable effects on SAR. Numerical calculations, based on the finite-difference time-domain (FDTD) method at 3 T, clearly show increased SAR around the non-conductive probes in a conductive phantom. 14:30 3883. Reduction of RF Heating of Metallic Devices Using Transmit Arrays Yigitcan Eryaman1, Taner Demir1, Ergin Atalar1 1UMRAM,National Research Center for Magnetic Resonance,Department of Electrical Engineering, Bilkent Univesity, Ankara, Turkey In this work shown it is shown that RF heating due to metallic devices in MRI can be reduced with Transmit Arrays. Additionally whole body average SAR can be reduced without sacrificing homogeneity. Stefanie Buchenau1, Martin Haas1, Jürgen Hennig1, Maxim Zaitsev1 1Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany To assure patient safety during parallel excitation experiments, monitoring of the RF pulses is necessary. If no additional hardware is available that measures RF phases a common approach is a conservative worst-case analysis that assumes absolutely constructive interference of the electric fields. This work shows that due to the varying phase settings during a parallel excitation pulse, worst-case SAR that may occur for single time steps is averaged over the pulse duration. This still holds true if the designed RF pulse is erroneously executed. Therefore conservative worst-case analysis overestimates SAR and it is possible to relax RF power limits that are based on this worst-case analysis. Hall B Monday 14:00-16:00 Computer 49 Volkan Acikel1,2, Burak Akin2, Ibrahim Mahcicek2, Ergin Atalar1,2 1Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey; 2UMRAM, Ankara, Turkey MRI examination of patients with medical implants has risks due to RF field. RF heating of implant lead tips can cause tissue burns. Although this problem has been examined several times both by experimentally and computer simulations there is not an analytical solution exists. In our study we used MoTLiM, which solves induced currents on leads analytically, to calculate implant tip heating. Then we compare it with experimental methods. According to these calculations we saw that MoTLiM is accurate enough to calculate implant tip heating. As MoTLiM gives analytical results for problem a deeper understanding of problem can be achieved. Linda Kuusela1,2, Sampsa Turunen1,3, Outi Sipilä1 1HUS Helsinki Medical Imaging Center, Helsinki (HUS), Finland; 2Department of Physics, Univeristy of Helsinki, Helsinki, Finland; 3Department of Physics, University of Helsinki, Helsinki, Finland An EEG-fMRI protocol is being developed at the Helsinki Medical Imaging Center to aid in the pre-surgical evaluation of patients with epilepsy. The purpose of this study was to study the heating of the electrodes with our protocol. Phantom and volunteer studies were performed, by measuring the temperatures of the EEG-electrodes in a 3T MRI scanner. A maximum temperature increase of 4.1 and 1.0º C was observed for a T2-TSE sequence in the phantom and the volunteer study, respectively. The temperature increase was found to be within safe limits to perform simultaneous EEG-fMRI patient studies with our protocol. 15:00 3887. Magnetic and RF Characterization of Stents Using Magnetic Resonance Imaging Karl-Heinz Herrmann1, Anne Rösler2,3, Andreas Hansch4, Stefan OR Pfleiderer5, Jürgen R. Reichenbach2 1Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital , Jena, Thüringen, Germany; 2Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Thüringen, Germany; 3Department of Medical Engineering and Biotechnology, University of Applied Sciences, Jena, Germany; 4Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany; 5Central Institute for Diagnostics and Nuclear Medicine, Clinical Center Bremerhaven-Reinkenheide, Germany While some manufacturers provide MR compatibility certifications for stents, the actual imaging artifacts after implantation may still vary widely. To assess and predict imaging artifacts produced by implanted stents, characterization of both, magnetic and rf properties, is necessary. In this study effective susceptibilities and maps of the flip angle distribution were determined from MR imaging data for different stent types.
15:30 3888. A FMRI Compatible Thumb Actuator for Stroke Patients Ewa Piatkowska-Janko1, Grzegorz Goworek1, Artur Handke2, Tomasz Wolak3, Maciej Krawczyk4, Piotr Bogorodzki1 1Institute of Radioelectronics, Warsaw University of Technology, Warsaw, Poland; 2Wroclaw University of Technology, Poland; 3Institute of Physiology and Pathology of Hearing, Poland; 4Institute of Psychiatry and Neurology, Poland In order to overcome limitations of fMRI for disabled patients we propose a pneumatical mechanical system helping them in fMRI motor stimulation paradigms. Results for group of healthy volunteers right and left handed were preset. Preliminary results for patient monitoring during rehabilitation time were also presented. Tuesday 13:30-15:30 Computer 49 13:30 3889. Safety in EEG-MRI: Heating Beneath EEG Scalp Electrodes for Different RF Transmit Coils Ulrike Nöth1, Helmut Laufs, 1,2, Robert Stoermer3, Ralf Deichmann1 1Brain Imaging Center (BIC), Goethe University Frankfurt am Main, Frankfurt am Main, Germany; 2Department of Neurology, Goethe University Frankfurt am Main, Frankfurt am Main, Germany; 3Brain Products GmbH, Gilching, Germany The heating beneath eight EEG scalp electrodes during simultaneous EEG-MRI acquisition was measured in vivo, using various MR sequences covering a wide range of SAR values. RF transmission was performed with a head and a body coil in comparison. Temperature increases beneath the electrodes were stronger and more frequent for the body coil, and fitted equilibrium temperatures reached the critical level of 41°C for high SAR sequences. This is of special interest as many scanners are not routinely equipped with a head transmit coil. Reinhard Rzanny1, Andreas Hansch2, Alexander Pfeil3, Alexander Gussew1, Stefanie Drobnik4, Jürgen R. Reichenbach5 1Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany; 2Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany; 3Department of Internal Medicine III, Jena University Hospital, Jena, Germany; 4Department of Cardiothoracic Surgery, Jena University Hospital, Jena, Germany; 5Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany The presence of pacemaker leads is considered to be a safety contraindication for MRI. To measure heating effects at the tip of temporary pacemaker leads, the frequency shift of water was estimated by single voxel 1H-MRS. The temperature dependence of the water frequency in the myocardial tissue was estimated in prior preliminary experiments during 3 warming and cooling cycles of a heart between 20 and 40°C. As a result of applying several MR imaging sequences on 12 pig hearts with implanted temporary pacemaker leads in a whole body MRI (1.5 T), no substantial heating was observed. Peter Nordbeck1,2, Oliver Ritter1, Ingo Weiss3, Daniel Gensler2, Marcus Warmuth2, Volker Herold2, Peter M. Jakob2, Mark E. Ladd4, Harald H. Quick5, Wolfgang R. Bauer1 1Internal Medicine I, University of Würzburg, Würzburg, Germany; 2Experimental Physics V, University of Würzburg, Würzburg, Germany; 3Biotronik GmbH & Co. KG, Berlin, Germany; 4Diagnostic and Interventional Radiology, University of Duisburg-Essen, Essen, Germany; 5Medical Physics, University Erlangen-Nürnberg, Erlangen, Germany The purpose of this study was to further assess the impact of the imaging landmark on the risk for unintended MRI-induced implant heating by measuring the RF-induced electric fields in a body phantom under several imaging conditions at 1.5 T in 3 different scanners. The results show that global RF coupling is highest with the torso centered along the superior-inferior direction of the transmit coil. The induced E-fields inside the body shift when changing body positioning. Potential hazards can be reduced by adequate selection of MR imaging landmark in patients with implanted medical devices. Holly Moschiano1, Warren Dabney1, Robert S. Johnson1, Lana Placek1 1Greatbatch Medical, Clarence, NY, United States Polyacrylic acid (PAA) gel has been used historically as the phantom material in MRI testing of passive and active medical implants. However, PAA exhibits undesirable variability in bulk electrical and thermal properties due to the presence of crystallites. Hydroxyethyl Cellulose (HEC) gel has been referenced in the most recent version of ASTM F 2182-02a as an acceptable substitute for PAA gel. HEC gel has similar electrical, thermal, and materials properties as PAA gel. Variations in electrical conductivity and specific heat capacity can greatly affect the amount of temperature rise seen in a test phantom in an MRI environment. Wednesday 13:30-15:30 Computer 49 13:30 3893. Insulation, Lead-Length, and Sample-Size Affect the MRI-Safety of Implanted Leads - not available Ananda Kumar1, Perry Karmarkar1, William A. Edelstein1, Paul A. Bottomley1 1Suite B307, 1101 E 33rd Street, SurgiVision Inc, Baltimore, MD, United States Concerns about RF heating of implanted devices precludes MRI for many patients who could otherwise benefit. Implanted leads are insulated and vary in length, depending on function and patient size. We investigated experimentally and theoretically the local specific absorption rate (SAR) and heating of leads as a function of sample size, lead length, and insulation thickness in gel phantoms exposed to 4W/kg at 1.5T. Heating and SAR are maximum at the bare electrode, increasing with lead insulation thickness and sample size. SAR is highly nonuniform so sensor sampling volume is critical for matching local theoretical SAR with measured temperature changes. 14:00 3894. Effect of Linear Phase Electric Field Variation on Implant Lead Heating Yigitcan Eryaman1, Volkan Acikel1, Esra Abaci Turk1, Nikolay Vladimirovic Viskusenko1, Ergin Atalar1 1UMRAM,National Magnetic Resonance Research Center,Department of Electrical Engineering, Bilkent Univesity, Ankara, Turkey In this work it is shown that a helical lead experiences a linear phase electric field variation in a typical quadrature birdcage coil. It is demonstrated that the effect of linear phase excitation maximizes heating at one tip and minimizes the heating at the other one. 14:30 3895. Changing Boundary Conditions: Effects on Catheter Heating Samuel O. Oduneye1, Sudip Ghate2, Kevan JT Anderson1, Graham A. Wright1 1Medical Biophysics, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; 2Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada During an MRI examination induced radio frequency (RF) currents on electric conductors, such as electrode lines within catheters, may cause heating in surrounding regions .The objective of this study was to investigate the effects of RF induced heating as a result of changing boundary conditions at the point of connection of a catheter to the MR-guided clinical system. In our setup, the termination represents a sudden change of impedance, an additional reflection point, where heating occurs; both simulation and experimental results show that this point alters significantly the current along the wire, the overall reflection coefficient and heating properties. Harald Busse1, Gregor Thörmer1, Nikita Garnov1, Jürgen Haase2, Thomas Kahn1, Michael Moche1 1Diagnostic and Interventional Radiology, Leipzig University Hospital, Leipzig, Germany; 2Physics and Geosciences Department, Leipzig University, Leipzig, Germany Applications in interventional MR angiography would potentially benefit from a safe and reliable localization of guidewires and catheters. Small inductively coupled RF coils have already been suggested or used as MR-visible markers for various purposes. When using such markers inside the body, however, inductively coupling during RF-intense MRI may pose a safety hazard. We have therefore investigated RF-exposed markers mounted on an intravascular model catheter and submerged in a vessel phantom under different flow conditions. While a considerable but small heating (<1°C) was observed under extreme conditions without flow, a negligible heating (<0.1°) was observed under a small volume flow. Thursday 13:30-15:30 Computer 49 Haydar Celik1,2, Namik Sengezer3, Burak Akin2, Dogac Mehmet Gulnerman3, Burcu Cingoz Insal4, Can Kerse, 23, Ergin Atalar, 23 1Electrical and Electronics Engineering, Bilkent University , Ankara, Turkey; 2National Magnetic Resonance Research Center (UMRAM), Ankara, Turkey; 3Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey; 4Moleculer Biology and Genetics, Bilkent University, Ankara, Turkey MRI has been used to image deep brain stimulator (DBS) lead and fMRI studies have been conducted in order to understand stimulation profiles of the electrodes. Both placement and functionality of the lead are vital. However, DBS leads may cause severe results because of the RF and gradient fields. Previously, a fiber optic signal transmission system was presented by authors. In this study, an important extension is proposed in order to maximize safety profile of the system. Proposed feedback mechanism enables monitoring of the induced current to the brain. Any rise or fall of the current is a possible reason of changing conductivity due to RF heating. Therefore, monitoring this quantity provides opportunity for better safety profile. In this study, in-vivo and in-vitro safety experiments have been conducted. 14:00 3898. Skin Injury Experienced During MRI Scans: Measurements of Body Coil Electric Field Sunder S. Rajan1, Marta Zanchi2, Howard Bassen3, Paul Hardy4, Joshua Gaug3 1Div of physics, fda/cdrh/osel, Silver Spring, MD, United States; 2Stanford University; 3FDA/CDRH/OSEL; 4FDA/CDRH/ODE The aim of this study is to evaluate the incidence of skin-injuries caused by contact with the magnet-bore and to explore whether the electric-fields are responsible. The FDA database was searched for events. Skin-injuries increased from 5-67 cases /yr between 1998-2009. A significant fraction was from contact with magnet-bore. The E-field at the wall of a stand-alone body-coil was measured using three devices. The E fields in air showed peaks in the vicinity of the capacitors. The field values decreased with distance from the capacitors. The maximum values with 20W CW in air were 3.0, 2.04 at wall and 0.95KV/m at 2 cm. 14:30 3899. Brain Tissue Response to Chronically Implanted NMR Microcoils Aziz Kadjo1, Jean-christophe Brisset1, Minh-Dung Hoang1,2, Patrick Poulichet3, Colette Rousset4, Abdennasser Fakri3, Youssef Z. Wadghiri, Marlène Wiart1, Lionel Rousseau3, Raymond Cespuglio4, Andre Briguet1, Danielle Graveron-Demilly1, Latifa Fakri-Bouchet1 1Université Lyon1, CREATIS-LRMN CNRS UMR 5220, INSERM U630, Villeurbanne, France; 2 NYU, New York University, School of Medicine, Center for Biomedical Imaging, 10016 NY, United States; 3ESIEE Paris, Lab. de Technologie avancée en microélectronique ESYCOM,EA 2552, Noisy Le Grand, France; 4Université Lyon1, Lab. «Radicaux libres/substrats énergie et physiopathologie cérébrale.» EA 4170, Lyon, France New generation of implantable microcoils proposed for localized spectroscopic studies of NMR observable cerebral metabolites into 2mm3 region of interest Latero Dorsal Tegumentum (LDT), aims at pushing limits of in vivo detection. However microantenna active part introduction into the brain can generate irreversible damage and inflammation that can distort spectroscopic measurements. This longitudinal study was performed on two healthy cohorts of implanted and control rat via MRI and confirmed by histopathology. The results show brain tissue response against implantable NMR microcoil and demonstrate the limited brain tissue reaction associated to the chronic microcoils implantion.
15:00 3900. Technical and Safety Aspects in Concurrent TMS/fMRI Paolo Ferrari1, Luigi Cattaneo1, Jens Volkmar Schwarzbach1, Marco Sandrini1, Jorge Jovicich1 1Center for Mind/Brain Sciences, University of Trento, Mattarello, Trento, Italy Transcranial magnetic stimulation (TMS) is an important method for cognitive neuroscience research in noninvasive stimulation of the human cortex combined with fMRI. The high magnetic field strength of modern MRI scanners imposes several limitations and challenges for its simultaneous combination with TMS. Our goal was to investigate technical and safety aspects in concurrent TMS/fMRI: 1) temperature characterization of the TMS coil, 2) synchronization procedure for TMS stimulation in concurrent TMS/fMRI. The implementation of the thermal curve help the planning of the TMS/fMRI protocols. With the external control system is possible to minimize the risk for patient and the scanner. Intraluminal, Micro & Cryo Coils Hall B Monday 14:00-16:00 Computer 50 14:00 3901. Inductively Coupled Birdcage Coil Haydar Celik1,2, Dogac Mehmet Gulnerman3, Burak Akin2, Ergin Atalar, 23 1Electrical and Electronics Engineering, Bilkent University , Ankara, Turkey; 2National Magnetic Resonance Research Center (UMRAM), Ankara, Turkey; 3Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey Although birdcage coils are essential elements of modern MRI scanners, they have never been miniaturized for placement inside body orifices such as the rectum and used as inductively coupled coil elements. In this study, inductively coupled birdcage coil (ICBC) and receive coupled birdcage coil (RCBC) are introduced as internal coil. These coils can be used without modifying the scanner hardware and do not affect tuning of external coils. ICBC coils are not connected to the scanner by wires; rather the MR signal picked up by these coils is transferred to a receiving coil by induction. Therefore, they are system independent. 14:30 3902. SNR and B1 Homogeneity Analysis of Intra-Vascular/Cavity RF Coil Designs Scott B. King1, Jesse Bellec2, Vyacheslav Volotovskyy1, Hung-Yu Lin1, Christopher P. Bidinosti2, Krzysztof Jasinski3, Mike J. Smith1, Boguslaw Tomanek4 1Institute for Biodiagnostics, National Research Council of Canada, Winnipeg, Manitoba, Canada; 2Department of Physics, University of Winnipeg, Winnipeg, Manitoba, Canada; 3Department of Magnetic Resonance Imaging, Polish Academy of Sciences, H. Niewodniczanski Institute of Nuclear Physics, Krakow, Poland; 4Institute for Biodiagnostics (West), National Research Council of Canada, Calgary, Alberta, Canada High spatial resolution vessel/cavity wall MRI requires a signal-to-noise ratio much higher than can be achieved using external phased array coils, so intravascular RF coils are used directly adjacent to the vessel of interest. Concentric birdcage designs are interesting in that they maintain the longitudinal SNR coverage, but also demonstrate some radial homogeneity albeit with azimuthal asymmetries that may not be ideal. Multi-turn crossed loops are another good design retaining the forward looking capability and orientation independence previously reported, but now with good longitudinal SNR coverage. These designs may offer alternatives to the low SNR opposed solenoid design. 15:00 3903. Coil Design for Imaging the Uterine Cervix at 3T. Control of R.f. Eddy Currents. David John Gilderdale1,2, Maria Angelica Schmidt1, Nandita Maria deSouza1 1Cancer Research UK & EPSRC Cancer Imaging Centre, Institute of Cancer Research & Royal Marsden NHS Foundation Trust, Sutton, Surrey, United Kingdom; 2Pulseteq Ltd, Wotton-under-Edge, Gloucestershire, United Kingdom A single-turn enveloping solenoid receive-only coil can produce significant shielding of the excitation field. This effect is independent of currents circulating around a resonant loop, which are normally removed with a suitable blocking circuit. The B1 distortion resulting from these extraneous r.f. eddy currents is demonstrated by EM simulation and also by MR imaging. A simple multi-turn modification to the structure is investigated and shown virtually to eliminate the field distortion. 15:30 3904. Design of a Double Tuned TxRx 1H/ 31P Endorectal Prostate Coil for 7T Mark J. van Uden1, Andor Veltien1, Tom W.J. Scheenen1, Arend Heerschap1 1Radiology, Radboud University Nijmegen Medical Center, Nijmegen, Gelderland, Netherlands The use of an endorectal 31P coil at high magnetic field strength might provide opportunities to sample signals from energy and phospholipid compounds with a clinically relevant spatial resolution in the prostates of patients with prostate cancer. We present a double tuned coil concept that can be fit inside the housing of an endorectal balloon coil design so that it can be positioned close to the organ for optimum receive performance. The double tuned coil design was built and tested for SNR in comparison with two single resonant coils (1H and 31P). Tuesday 13:30-15:30 Computer 50 13:30 3905. Inductive and Dielectric Tuning Techniques for High-Sensitivity Miniature Monolithic Surface Coils. Jean-Clément Guisiano1,2, Simon Lambert1, Souhil Megherbi2, Jean-Christophe Ginefri1 1U2R2M, Orsay, France; 2IEF, Orsay, France Dedicated tuning techniques for high-sensitivity miniature monolithic coils are needed. Inductive and dielectric tuning techniques were investigated using experimental measurements, analytical model or numerical simulations. Maximum frequency shifts of 15.3% for the inductive tuning and 9.9% for the dielectric tuning were reported. A mean deviation of 1% between experiments and the proposed inductive model and 2% between experiments and simulations for the dielectric tuning were achieved. The influence of both technique on the quality factor was discussed. A piezoelectric-based displacement device was proposed to perform a precise positioning of a tuning element and a fine resonance frequency control. 14:00 3906. Development of Multilayer Coil Using Non-Planar MEMS Process for Intraluminal MRI Probe - not available Shizuo Ichimura1, Wei Quan2, Tadao Matsunaga2, Yuichiro Matsuoka3, Kagayaki Kuroda4, Yoichi Haga2 1KANEKA Corporation, Settsu, Osaka, Japan; 2Graduate School of Biomedical Engineering, Tohoku University, Sendai, Miyagi, Japan; 3Graduate School of Medicine, Kobe University, Japan; 4Dept. of Human & Information Science, Tokai University, Japan Intraluminal MRI probe holds promise to achieve high resolution image of small pathological lesion such as the vessel plaque comparing to the conventional MRI scanner. The MR signal receive coil is expected to be characterized by high signal-noise-ratio (SNR), good signal homogeneity and small size. By employing the developed photolithography technology on cylinder substrates, the MRI receive coil for the intraluminal application can be fabricated arbitrarily with the accurate and optimized shape. Comparing to previous single layer coil, this study presents the design of the multilayer receive coil for improving the imaging performance. 14:30 3907. B1 and B0 Mapping of a Micro Helix Coil at 9.4T Mohammad Mohammadzadeh1, Hans Weber1, Nicoleta Baxan1, Vlad Badilita2, Julian Maclaren1, Jurgen Hennig1, Dominik v. Elverfeldt1 1Dept. of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany; 2Dept. of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg, Germany In this study the performance of a five turns micro helix coil wound on an SU8 cylinder, was evaluated by mapping its 2D B1 and B0 field’s distribution. These tests are done inside doped water phantom, on a 9.4T using 3D GE sequences. B1 maps are acquired using multi flip angle MFA method and B0 mapping are performed by measuring frequency deviation inside a doped water phantom. In General, Results show that coil has enough SNR and provides minimum frequency deviation and maximum B1 uniformity across the sample and particularly at the coil center. Nikita Garnov1, Gregor Thörmer1, Wilfried Gründer2, Robert Trampel3, Michael Moche1, Thomas Kahn1, Harald Busse1 1Diagnostic and Interventional Radiology, Leipzig University Hospital, Leipzig, Germany; 2Institute of Medical Physics and Biophysics, University of Leipzig, Leipzig, Germany; 3Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany Small inductively coupled RF coils in solenoid design were systematically evaluated as MR-visible markers at 1.5T. Coil performance was assessed for different flip angles, ±240 mm translations from the isocenter, and tilting of the coil axis with respect to the transverse plane using a balanced SSFP sequence. Marker contrast was highest at very low FAs (0.2°-0.6°) and was also sufficiently high for automatic marker detection throughout the entire FOV and for tilt angles up to 55°. Coil heating was measured during 10-minute RF expositions using different clinical pulse sequences (SAR<2 W/kg) and found to be tolerable (<5°C) for extracorporal application. Wednesday 13:30-15:00 Computer 50 13:30 3909. A Novel Nanomaterial Coil for High Resolution Prostate Imaging - not available Raju Viswanathan1, Bradley Goldstein1, Kevan Anderson2, Axel Krieger3 1Tursiop Technologies, LLC, Cleveland, OH, United States; 2Sunnybrook Health Sciences Center, University of Toronto, Toronto, Ontario, Canada; 3Sentinelle Medical Inc., Toronto, Ontario, Canada An emerging RF coil technology based on a new nanostructured material was recently introduced. This material can be macroscopically configured in a mechanically robust ribbon or string form comprised of carbon nanotubes. The material can provide a combination of increased inductance and reduced resistance that permits building MR receive coils with enhanced SNR. Here this is explicitly demonstrated in a prototype prostate imaging “nanocoil” that was built to fit into a commercial endorectal prostate imaging probe. It is shown that with a single channel nanocoil, SNR profiles similar to those from a standard but advanced dual-channel array can be generated. 14:00 3910. Investigation of Decoupling Techniques for Two-Element Cryogenic Arrays Jarek Wosik1,2, Leiming Xie1, Lian Xue3, Krzysztof Nesteruk4, Kurt H. Bockhorst3, Ponnada A. Narayana3 1Electrical and Computer Engineering, University of Houston, Houston, TX, United States; 2Texas Center for Superconductivity, Houston, TX, United States; 3Diagnostic and Interventional Imaging, University of Texas, Health Science Center-Houston Medical School, Houston, TX, United States; 4Institute of Physics Polish Academy of Sciences, Warsaw, Poland In order to address constrains regarding low loss decoupling techniques for application in high-Q cryogenic arrays, we evaluated and compared SNR gain from cooling to liquid nitrogen temperatures of 2x1 array at 7 Tesla for three different decoupling methods. Beside standard overlapping approach we have also used “eight shape” loop and capacitive decoupling techniques. Calculations and experimental results showed the best performance (two fold SNR gain) of the array with capacitive decoupling. The “eight shape” loop decoupled array showed only a few percent lower SNR gain, whereas the geometrical decoupling technique had reduced SNR gain by close to 20%. Bobo Hu1, Gopal Varma2, Stephen Keevil2, Chris Randell3, Paul Glover4 1Sir Peter Mansfield Magnetic Resonance Centre , University of Nottingham, Nottingham, United Kingdom; 2St Thomas¡¯s Hospital, Kings College, London, United Kingdom; 3Pulseteq Ltd., Wotton-under-Edge, Gloucestershire, United Kingdom; 4Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, United Kingdom The performance of a liquid nitrogen cooled receive-only copper coil to acquire micron scale high resolution mouse imaging on a 3T whole body scanner is investigated. In this work a novel cryostat design, which provides easy access for small animal samples, is described. The receive coil is a 2 cm diameter copper coil with active decoupling during transmission. The Q factor of the coil has been enhanced by 60% after cooling down for 1 hour to reach 120 K, and the SNR performance has increased by 2 fold compared with the room temperature version of the same coil. Thursday 13:30-15:30 Computer 50 Jean-Christophe Ginefri1, Marie Poirier-Quinot1, Luc Darrasse1 1Unité de Recherche en Résonance Mgnétique Médicale, CNRS-Université Paris-Sud, Orsay, France The optimization of the SNR achievable with a small High Temperature Superconducting (HTS) surface coil is investigated as a function of the sample size and position using theoretical analysis, inductive measurements, and MRI experiments at 1.5 T. This study was conducted with a 6mm HTS coil operating at 77 K and small conductive saline phantoms. SNR measured on phantom images are in good agreement with theoretical data and inductive measurements and demonstrate the existence of an optimal distance between the sample and the HTS coil for which the SNR is maximum and that depends on the loading configuration. 14:00 3913. Whole Body Screening Using High-Temperature Superconducting MR Volume Coils: - not available In-Tsang Lin1, Hong-Chang Yang2, Jyh-Horng Chen1 1Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, Graduate Institute of Biomedical Electronics and Bioinformatics, Taiper, 106, Taiwan; 2Department of Physics, National Taiwan University, Taipei 106, Taiwan Previous studies on HTS coils can be put into two categories: tape surface coils and thin-film surface coils[1-4]. In this study, we built a whole new Bi2Sr2Ca2Cu2O3 (Bi-2223) superconducting volume coil (length of 8 cm) designed for magnetic resonance image of the mice whole body at Bruker 3T MRI system. The HTS volume coil has 2.3 folds higher than of the HTS volume coil at 300K for a mice body screen. 14:30 3914. Development of Stable Cryo Probe and HTS Helmholtz Coil for Clinical Application Jack Liu1, C. W. Hu1, Q. Y. Ma1 1Time Medical Inc., Shanghai, China Development of HTS surface and Helmholtz coils for orthopedic imaging with improvement of both SNR and penetration depth. 15:00 3915. A Long Duration High-Temperature Superconducting RF Platform - not available In-Tsang Lin1, Hong-Chang Yang2, Jyh-Horng Chen1 1Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, Graduate Institute of Biomedical Electronics and Bioinformatics, Taiper, 106, Taiwan; 2Department of Physics, National Taiwan University, Taipei 106, Taiwan High-temperature superconducting (HTS) radio-frequency (RF) coil has been proposed as a promising tool for MR microscopy due to its zero-resistance characteristic for the MR probe design. However, the cryogenic system is very difficult to design due to its thermal insulation demands. In this study, we have succeeded to design a longitudinal dewar that can keep animal body temperature for more than three hours. A 40 mm in diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) tape HTS RF coil with this dewar was demonstrated. The signal to noise gain is 3.79 compared to the copper coil with the same geometry at room temperature. Coil Interfacing: LNA's, Baluns & Decoupling Hall B Monday 14:00-16:00 Computer 51 14:00 3916. Variation of Preamplifier Noise Figure with B0 Field Strength Nicola De Zanche1,2, Brodi Roberts, 1,2, B. Gino Fallone1,2 1Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada; 2Department of Oncology, University of Alberta, Edmonton, Alberta, Canada Preamplifier S parameters are known to vary with B0 field strength and orientation. Variations in noise figure are also expected, but such data has not been reported until now. Here we present the variation of noise figure of a commercially available amplifier (MAR 8A+, Mini-Circuits, USA) at field strengths up to 9.4 T. The method allows arbitrary noise source impedances for complete noise parameter measurement, if desired. Variations in noise source power (ENR) with applied field are prevented by locating the noise source outside the field. 14:30 3917. Automated Preamplifier Noise Parameter Measurement System Using a Combination Analyzer Brodi Roberts1,2, B. Gino Fallone, 1,2, Nicola De Zanche, 1,2 1Department of Oncology, University of Alberta, Edmonton, Alberta, Canada; 2Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada Optimal matching between each coil in an array and its respective amplifier requires knowledge of its noise parameters, which are rarely available from manufacturers at MRI frequencies. Measuring noise parameters is also needed to identify inter-device variability. The system we describe is based on a common combination spectrum / network analyzer, which, unlike noise figure analyzers, allows the measurement of S parameters. Corrections can thus be readily implemented for noise reflections at various stages of the system. The LabVIEW instrument control environment is used to automate calibration, measurement, and data processing. 15:00 3918. High Input Impedance LNA with Passive Negative Feedback for High Field Imaging - not available Cecilia Possanzini1, Marco Boutelje1, Rudolf Kunnen1 1MR Development, Philips Healthcare, Best, Netherlands In this paper, we show the design of a high impedance amplifier using a passive negative feedback in order to improve manufacturability and reproducibility. The noise figure, gain, and stability of the preamplifier has been simulated with a non linear model and measured on different samples at 3T. 15:30 3919. MRI Coil Stability Selaka Bandara Bulumulla1, Wolfgang Loew2, Christopher J. Hardy1 1GE Global Research, Niskayuna, NY, United States; 2GE Global Research, Munich, Germany MRI receiver chains that are carefully tuned and matched to operate at the Larmor frequency are often prone to oscillations at other, nearby frequencies. These oscillations degrade image quality, yet isolating and eliminating oscillations is a challenge in large arrays, and significantly add to development cycle. In this work, we develop methods to analyze and predict the stability of coil arrays given preamp data, coil/balun/feedboard circuits and geometry. The method is used to predict the stability of a coil array at the Larmor and nearby frequencies, for varying conditions of coil loading and preamp termination, and compared with experimental results. Tuesday 13:30-15:30 Computer 51 13:30 3920. An Automatic Impedance Matching System for Multiple Frequency Coils Sien Wu1, Barbara L. Beck2, Walker J. Turner1, Rizwan Bashirullah1, Thomas Mareci3 1Electrical and Computer Engineering, University of Florida, Gainesville, FL, United States; 2McKnight Brain Institute, University of Florida, Gainesville, FL, United States; 3Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States This Automatic Impedance Matching system is designed to tune and match multiple frequency coils in order to monitor multiple nuclei of an artificial pancreas for Type I diabetes. This system uses an impedance sensing circuit to measure the reflected signal of the coil at the frequency of interest and a microcontroller to tune and match the coil. A prototype of the Automatic Impedance Matching system described in this report successfully demonstrates the capability to tune and match a simplified double frequency coil, and the system design can be extended to multiple frequency coils. 14:00 3921. Quarter Wave Multi Layer Cable Balun Victor Taracila1, Vijayanand Alagappan1, Aleksey Zemskov1, Fraser Robb1 1GE Healthcare, Aurora, OH, United States One of the critical problems coil designer confront is the parasitic current induced on the cables during transmit phase of the MRI sequence. During receive phase cables must not couple to the multiple coil elements, otherwise shading, oscillations and heating could occur. Typical method of reducing the current on cables is by utilizing cable baluns. In this work we try to accommodate the well-known quarter wave balun to the low frequencies without adding length to the signal transmission line and without adding any lumped circuit components. 14:30 3922. Six Layers Stripline RF-Invisible Balun Victor Taracila1, Aleksey Zemskov1, Vijayanand Alagappan1, Fraser Robb1 1GE Healthcare, Aurora, OH, United States In the well-known preamplifier decoupling technique, a low input impedance preamplifier in series with an inductor attached to the matching capacitor is utilized. One of the problem of this design is the inductor’s stray field and preamplifier’s ground disturbance. When using a balun in front of the preamplifier, the transmission line from which the balun is composed creates the needed inductance. Also, providing high impedance on the outer shield of the balun, amplifier ground is kept unperturbed. In this work we present the RF-invisible balun based on double spiral inductor shape and its PCB implementation. Chang-Hoon Choi1, Ioannis Lavdas1, James M. S. Hutchison1, David J. Lurie1 1Aberdeen Biomedical Imaging Centre, University of Aberdeen, Aberdeen, Scotland, United Kingdom An off-resonance RF pre-saturation pulse is typically employed for magnetisation transfer contrast MRI. Measuring the magnetisation transfer (MT) effect as a function of magnetic field (B0) may provide valuable. In order to conduct field-dependent MT experiments, two techniques are required. Firstly, B0 should be switched between levels by fast field-cycling during irradiation of the saturation pulse, and secondly the resonance frequency of the resonator (f0) should also be shifted simultaneously. Here, we constructed the frequency-switchable RF coil using PIN diodes. (f0) is actively switched between five different values, with excellent impendent matching (about -40dB) and the Q-factor (approximately 80). Wednesday 13:30-15:30 Computer 51 13:30 3924. Optimizing Pin Diode Performance in Transceiver Coils Feng Zhou1, Mirko I. Hrovat2 1Dept. of Physics, University of Massachusetts Lowell, Lowell, MA, United States; 2Mirtech, Inc., Brockton, MA, United States A simple parallel pin-diode configuration is demonstrated to provide better performance than traditional pin diode circuits in transceiver coils. With this configuration, there are no special requirements such as high power ratings or high break down voltages for selecting the pin-diode. 14:00 3925. A High Dynamic Range Receiver for Improved Diffusion Tensor Imaging Wolfgang Gaggl1, Andrzej Jesmanowicz1, Robert W. Prost1 1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States Diffusion Tensor Imaging experiments require wide dynamic signal ranges, as they necessitate collecting an unweighted spin-echo image with a high intensity and a series of diffusion-weighted images with low intensities. Dynamic range increases with increasing the diffusion-weighting. Analog-digital converters with typical RF receivers have 16-bit resolution, while our system reaches over 20-bit. This is possible by direct-sampling the RF signal and downsampling it. Data from our receiver demonstrate superior signal-to-noise and diffusion-to-noise ratios and a dynamic range that is at least 4 bits wider than typical 16-bit receivers, shortening scanning durations and making it ideal for experiments with high diffusion-weighting. 14:30 3926. An Orthogonality Based RF Decoupling Method Hua Wang1, Bing Keong Joe Li1, Adnan Trakic1, Ewald Weber1, Craig Engstrom1, Yu Li1, Stuart Crozier1 1School of ITEE, The University of Queensland, Brisbane, QLD, Australia A conformal RF coil array design for use in a MRI system is proposed. In particular, the coil array is designed without the use of any cumbersome mutual decoupling schemes. Coil elements are designed based on orthogonality, which will naturally minimise the problematic mutual coupling effects inherently existed in most phased-array systems. A prototype of a knee coil constructed with this scheme is testified to be pertinent to Magic Angle applications. In addition, consistent imaging quality invariant to coil orientation with respect to B0, like B1 homogeneity, SNR and coil efficiency, can be obtained with the proposed orthogonality design. 15:00 3927. Tunable Geometric Decoupling Mechanisms for Phased Array Coils Sahil P. Bhatia1, Fraser J. Robb2, Yiping Guan2, Mary P. McDougall1 1Magnetic Resonance Systems Lab, Texas A & M University, College Station, TX, United States; 2G.E. Healthcare, Aurora, OH, United States Effective geometric decoupling between array elements becomes increasingly important when isolation preamplifiers are not available or employable, as is the case for certain field strengths and in the case of transmit array design. We present two methods of tunable geometric decoupling that allow the coil-to-coil decoupling to be adjustable and provide a straightforward mechanism for optimizing the overlap area. Bench measurements demonstrate the ability of both mechanisms to optimize decoupling between adjacent elements under a range of loading conditions, and imaging confirms that the addition of the mechanisms does not alter the field patterns or SNR of the coil elements. Thursday 13:30-15:30 Computer 51 13:30 3928. Minimal Acceptable Blocking Impedance for RF Receive Coils Victor Taracila1, Pei Chan1, Fraser Robb1 1GE Healthcare, Aurora, OH, United States During the transmit phase of the MR sequence the receiving coils are usually detuned to minimize body coil disturbance. This is typically achieved with passive or active decoupling parallel tank circuits which, when active, create very high impedance in coil elements so that the current induced into them is very small and does not affect the process of magnetization tipping. When planning the build of a coil, the magnitude and the number of decoupling boards required for every receive element needs to be considered. In this work we deduce a simple rule for quick evaluation of the required blocking impedance. 14:00 3929. Dynamic Modeling of Low Magnetic Moment PIN Diodes for MR Scanner Applications - not available Robert Caverly1, Ronald Watkins2, William Doherty3 1Electrical and Computer Engineering, Villanova University, Villanova, PA, United States; 2Radiology, Stanford University, Stanford, CA, United States; 3Lowell Division, Microsemi Corp., Lowell, MA, United States A SPICE-compatible PIN diode model suitable for time domain dynamic modeling is presented, with information for both fast rectifier and higher power devices design shown. 14:30 3930. Overlap Decoupling in Hole-Slotted Arrays Marcos Alonso Lopez1,2, Felix Breuer2, Daniel Gareis1,3, Peter Michael Jakob1,2 1Experimental Physics 5, University of Wuerzburg, Wuerzburg, Bavaria, Germany; 2Research Center Magnetic Resonance Bavaria, Wuerzburg, Bavaria, Germany; 3Noras MRI Products GmbH, Hoechberg, Bavaria, Germany The hole-slotted coil design provides a deeper RF penetration into the sample compared to standard loop designs and has already been shown to operate as an array with capacitive decoupling at 7 T. In this work, the applicability of overlap decoupling in a hole-slotted loop-geometry array is investigated at 1.5 and 7 T. The overlap ratio for an optimal decoupling has been experimentally found. The hole-slotted geometry is a well-suited design in an array setup using overlap decoupling. At 7 T has been shown to have approximately the same RF penetration than the hole-slotted array with capacitive decoupling. Jacob Bender1,2, Mihaela Jekic1,2, Orlando P. Simonetti1,3 1The Dorothy M. Davis Heart and Lung Research Institute, Ohio State University, Columbus, OH, United States; 2Biomedical Engineering, Ohio State University, Columbus, OH, United States; 3Radiology, Internal Medicine, Biomedical Engineering, Ohio State University, Columbus, OH, United States A 2.4 GHz MRI compatible Bluetooth transceiver was constructed for use with a mouse and keyboard inside of a MRI room. Shielding and filtering prevented noise from Bluetooth electronics from entering the room. Only a few required small ferromagnetic parts were incorporated into the design. No noise was generated from the system. This was verified visually with phantom scan, a frequency spectrum obtained with a network analyzer, quantitatively with RF noise checks, and through technical specification from the manufacturer, FCC, and ETSI. Hall B Monday 14:00-16:00 Computer 52 Hector Sanchez1, Michael Poole1, Adnan Trakic1, Stuart Crozier1 1Research Group/Affiliation: EMI, School of Information Technology & electrical Engineering, Brisbane, QLD, Australia MRI requires rapidly switched magnetic field gradients. This time-dependent magnetic fields induce eddy currents in nearby conducting structures. These currents generate detrimental transient magnetic fields in the region of interest (ROI) and hence, current compensation is required to minimize the consequential image distortion. In order to apply successfully current compensation techniques, it is required that the primary and the secondary magnetic fields possess a similar spatial form in the ROI. In this work we present two approaches for gradient coil design that produces gradient fields with characteristics similar to those produced by the eddy currents. 14:30 3933. Eigenmode Analysis of Eddy Currents and Eigenmode Coil Design Michael Stephen Poole1, Hector Sanchez Lopez1, Stuart Crozier1 1School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia Modelling gradient-induced eddy currents using eigenmode analysis reveals a set of non-interacting modes with characteristic exponential decays. These combine in conventional gradient coils to produce an eddy current that changes its magnitude and spatial form in time. This causes gradient pre-emphasis techniques to be ineffective over the whole imaging region. We propose, and demonstrate by simulation, that the eddy currents can be made more amenable to pre-emphasis by suppressing all but one mode. At the same time the primary field must match the field generated by this mode. 15:00 3934. Curved Gradient Coil Designs for Anatomically Specific Imaging Applications Chad Tyler Harris1, William B. Handler1, Blaine Alexander Chronik1 1Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada We have implemented a boundary element method to design and analyze the performance of curved gradient coil geometries as a function of the degree of curvature over all three axes, varying continuously from planar to full cylindrical. A form of curved gradient coil could serve as anatomically-specific gradient channels to be used in conjunction with whole-body coils to comprise a 4- to 6-channel hybrid system. The function of the anatomically-specific channels could include the ability to provide very high performance diffusion weighted imaging in a specified volume of tissue such as the breast, prostate, or posterior regions of the brain. 15:30 3935. Using Shape Optimization to Linearise the Eddy Current Field Hector Sanchez1, Michael Poole1, Stuart Crozier1 1Research Group/Affiliation: EMI, School of Information Technology & electrical Engineering, Brisbane, QLD, Australia MRI requires rapidly switched magnetic field gradients. This time-dependent magnetic fields induce eddy currents in nearby conducting structures. These currents generate detrimental transient magnetic fields in the region of interest (ROI) and hence current compensation (CC) is required to minimize the consequential image distortion. In order to apply successfully CC techniques, it is required that the primary and the secondary magnetic fields possess a similar spatial form in the ROI. We investigated by simulation, the effect of re-shaping a highly conducting passive shield surrounding a gradient coil (and the gradient coil surface) over the matching field for optimal current compensation. Tuesday 13:30-15:30 Computer 52 13:30 3936. Development of a New High-Performance PatLoc Gradient System for Small-Animal Imaging Stéphanie Ohrel1, Heinrich Lehr1, Frédéric Jaspard2, Peter Ullmann1, Hans Post1 1Bruker BioSpin MRI GmbH, Ettlingen, Germany; 2Bruker BioSpin SA, Wissembourg, France The experimental feasibility of PatLoc imaging at small-animal scale has been demonstrated in several studies. However, the limited performance provided by the PatLoc gradient prototype involved led to experimental restrictions like long echo and repetition times. This has been addressed in this study by developing a more efficient PatLoc gradient coil which can be driven with higher currents. Initial measurements demonstrate a twofold-increased efficiency of the new design which leads, together with the extended current limits, to a roughly tenfold-enhanced gradient strength. Furthermore, gradient-echo imaging could be performed with high quality using the new PatLoc gradient for in-plane spatial encoding. 14:00 3937. A 50-Channel Matrix Gradient System: A Feasibility Study Stefan Wintzheimer1, Toni Driessle2, Michael Ledwig1, Peter M. Jakob1,2, Florian Fidler1 1MRB, Research Center Magnetic-Resonance-Bavaria, Wuerzburg, BY, Germany; 2Experimental Physics 5, University of Wuerzburg, Wuerzburg, BY, Germany Shimming a magnetic field usually requires an additional set of complex coils which act independently from the linear gradient system used for MRI. In this study a novel matrix gradient design is presented, which is capable of generating both linear gradient fields for imaging and at the same time high order shim fields to compensate inhomogeneities in the main magnetic field. They provide the possibility to create a large variety of field profiles. Furthermore the new design is able to switch every field order very fast due to low inductivity of the coils. 14:30 3938. Designing 3D Gradient Coils for Open MRI Systems Peter T. While1, Larry K. Forbes1, Stuart Crozier2 1School of Maths and Physics, University of Tasmania, Hobart, TAS, Australia; 2School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia An analytic method is described for the theoretical design of 3D gradient coils for open MRI systems. Rather than restricting coil windings to planar surfaces, the precise 3D geometry is obtained as part of the optimisation. The inverse problem is solved using regularisation with a minimum power constraint. A priority streamline seeding technique is used to position the windings. Results for an unshielded coil display concentrated current near the DSV with looped return path windings. However, for a shielded coil the windings are confined to biplanar surfaces, suggesting this is the optimum geometry for a shielded minimum power open coil. 15:00 3939. A Split Gradient Coil for High Speed Imaging with Application to MRI-RT Shmaryu Shvartsman1, Gordon DeMeester1, Timothy Eagan1, Steve Bates2, Mark Savill2 1ViewRay Incorporated, Oakwood Village, OH, United States; 2Tesla Engineering Ltd, Storrington, West Sussex, United Kingdom It is desirable to have a high speed whole body gradient coil with a central gap between coils of 200mm for applications in MRI guided Radiation Therapy. Multileaved Collimators (MLCs) near the coil gap have conducting and possible eddy current surfaces that indicate avoidance of 3D coil design in this region. Our gapped coil design is different from the approach described in [1]. A similar design for a whole body gradient was analyzed in [2]. Radiation treatment monitoring requires continuous fast imaging for time intervals of 20min, so gapped gradient inefficiency and duty cycle requirements combine to increase cooling requirements. Wednesday 13:30-15:30 Computer 52 13:30 3940. Superelliptical Insert Gradient Coil with Field Modifying Layers for Breast MRI Sung M. Moon1, K. Craig Goodrich1, J. Rock Hadley1, Gengsheng Lawrence Zeng1, Glen Morrell1, Matthew A. McAlpine2, Blaine A. Chronik2, Dennis L. Parker1 1UCAIR (Utah Center for Advanced Imaging Research), Radiology, University of Utah, Salt Lake City, UT, United States; 2Physics and Astronomy, University of Western Ontario, London, Ontario, Canada With higher gradient strength and slew rate, planar insert gradients can attain higher spatial and temporal resolution than the body gradients. However, a homogeneous gradient volume of the planar gradient is relatively small due to its inherent geometry and exponential field fall-off with distance from the coil surface. Therefore, the HGV may be too small for breast imaging. In this work, to create wider HGV, the planar geometry was widened and the edges were bent vertically using superelliptical curvature on both sides, creating a so-called superellipse shape to fit in the magnet bore. These vertical edges increase the uniformity. Furthermore, an extra outer layer of current windings was added to increase its strength and homogeneity. 14:00 3941. Segmented Insert Gradient Coil for Bilateral Knee Imaging Sung M. Moon1, K. Craig Goodrich1, J Rock Hadley1, Dennis L. Parker1 1UCAIR (Utah Center for Advanced Imaging Research), Radiology, University of Utah, Salt Lake City, UT, United States MRI of the knee can benefit from high spatial resolution and short echo times for both proton and sodium-23 imaging of cartilage. With higher gradient strength and slew rate, the insert gradient coils can attain shorter echo times and higher spatial and temporal resolution than the body gradients. Prior flat gradient system designs have relatively smaller HGVs, which are not quite wide enough for bilateral knee imaging. To image both knees simultaneously, we have developed a segmented two-region insert gradient system which has two wide HGVs, one for each knee, along the x-axis. This was achieved by adding an extra vertical winding in the middle of the x-gradient to create high gradient strength, and by using superelliptical geometry, which enlarges the HGV dramatically by spreading wire patterns around both knees. 14:30 3942. Transversal Gradient Compensation in Three-Sided MRI Magnets Franco Bertora1, Alice Borceto1, Andrea Viale1 1Robotics, Brain and Cognitive Sciences, Italian Institute of Technology, GENOVA, GE, Italy The design of a fMRI magnet for the study of the human motor cortex poses a number of challenges due to the necessity of maintaining the subject in a natural, erect position, with free access to the environment. One way of meeting the challenge is to center the design around a three-dimensional finite configuration containing a closed cavity where the field is homogeneous. When the cavity is open to allow patient access a strong gradient arises that needs to be compensated without compromising the structure efficiency. 15:00 3943. Temperature Characteristics of Gradient Coils with Minimax Current Density Michael Stephen Poole1, Pierre Weiss2, Hector Sanchez Lopez1, Michael Ng3, Stuart Crozier1 1School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia; 2Institut de Mathematiques, Universite Paul Sabatier Toulouse 3, Toulouse, France; 3Department of Mathematics, Hong Kong Baptist University, Kowloon Tong, Hong Kong Gradient and shim coils designed with minimum power or stored energy can possess regions of high current density. A new method has been developed to spread out these areas of high current density, which should lead to lower peak temperatures. Here we test the heating properties of such minimax current density coils with and show that indeed the peak temperature is reduced in a model coil. Thursday 13:30-15:30 Computer 52 13:30 3944. Minimising Hot Spot Temperature in Gradient Coil Design Peter T. While1, Larry K. Forbes1, Stuart Crozier2 1School of Maths and Physics, University of Tasmania, Hobart, TAS, Australia; 2School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia Gradient coil hot spots can lead to image distortion and coil failure. An analytic method is presented for redesigning gradient coils with improved spatial temperature distributions and reduced hot spot temperatures. Maximum temperature is a non-linear constraint and a relaxed fixed point iteration scheme is introduced to alter the coil windings iteratively and lower the hot spot temperature. The new coil windings display a considerable improvement in hot spot temperature, at no cost to coil performance, when compared to equivalent minimum power x-gradient coils. The model can be adapted easily for other geometries, thermal properties, cooling mechanisms and non-linear constraints. 14:00 3945. A Temperature Distribution Model for Gradient Coils Peter T. While1, Larry K. Forbes1, Stuart Crozier2 1School of Maths and Physics, University of Tasmania, Hobart, TAS, Australia; 2School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia Excessive heating of gradient coils is a considerable concern. An analytic model is presented for calculating theoretically the spatial temperature distribution for cylindrical gradient coils. The model includes Ohmic heating due to current density in resistive material, thermal conduction through a copper layer and an epoxy former, and radial heat loss to the environment. A great number of coil parameters can be varied, including geometry, electrical and thermal properties, and results are shown for a standard x-gradient coil under three different types of cooling. In addition, temperature rise-times are predicted using a time-dependent solution for hot spot temperature. 14:30 3946. Safety Considerations for a PatLoc Gradient Insert Coil for Human Head Imaging - not available Chris A. Cocosco1, Andrew J. Dewdney2, P Dietz2, M Semmler2, Anna M. Welz1, Daniel Gallichan1, Hans Weber1, Gerrit Schultz1, Juergen Hennig1, Maxim Zaitsev1 1Dept of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, B.W., Germany; 2Siemens Healthcare, Erlangen, Germany We present the design considerations and evaluation measurements for the safety of a PatLoc (Parallel Acquisition Technique using Localized Gradients) gradient insert coil designed for human head imaging on a 3T MRI system. This novel concept has the potential to allow higher gradient switching rates while not exceeding the Peripheral Nerve Stimulation (PNS) limits. Based on the presented experimental measurements and simulations, we consider imaging human volunteers with this system to be safe. 15:00 3947. First Results for Diffusion-Weighted Imaging with a 4th Channel Gradient Insert Rebecca E. Feldman1, Jamu Alford2, Timothy Scholl2, Blaine A. Chronik2 1Medical Biophysics, University of Western Ontario, London, Ontario, Canada; 2Physics and Astronomy, University of Western Ontario, London, Ontario, Canada Gradients in diffusion-weighted imaging play two distinct roles. A gradient with a linear range sufficient to cover the sample is required for imaging. For the diffusion-weighting, the gradient is only required to be strong. A fourth gradient was inserted into the bore for the purposes of diffusion-weighting only. The inserted gradient was pulsed twice, before and after the 180 degree RF pulse, and the image acquisition was done using the whole body gradients. Using the insert b-values greater than 1000 s/mm2 were obtained a time frame that would permit only a b-value of 100 using the whole-body gradients. Hall B Monday 14:00-16:00 Computer 53 14:00 3948. A Depth-Encoding Detector Module for an MR-Compatible PET Insert Yibao Wu1, Yongfeng Yang1, Bo J. Peng1, Simon R. Cherry1 1Department of Biomedical Engineering, University of California, Davis, Davis, CA, United States The next generation of MR-compatible PET insert is under development for small-animal imaging providing greater than an order of magnitude increase in sensitivity by utilizing 20 mm thick scintillator crystal elements with excellent stopping power. A detector module based on avalanche photodiode read out with depth-of-interaction encoding was designed and evaluated to overcome the resolution-degrading parallax errors associated with such thick detectors. Detectors for the new PET insert were characterized in terms of crystal identification and energy spectra. Data were acquired outside a 7T MR scanner, inside the MR scanner, with and without sequences running. An MR phantom also was measured with the PET detector module inside the MR system. No significant interference between the PET detector module and the MR system were observed. The design of the new PET insert based on these detectors is presented. Geron Andre Bindseil1, Timothy J. Scholl1, William B. Handler1, Chad T. Harris1, Blaine A. Chronik1 1Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada Combining conventional PET and MRI faces numerous technical challenges, particularly the sensitivity of photomultiplier tube-based (PMT) PET detectors to magnetic fields. The authors describe an approach to PET/MRI in which a resistive electromagnet shield is used to null the field at the PMTs of a conventional PET system in the vicinity of a superconducting MRI system. The electromagnetic characteristics of the shield coil are presented. This approach benefits from allowing the use of commercially available PET systems, which include state-of-the-art timing & energy resolution, high sensitivity, and highly optimized event processing hardware. 15:00 3950. Minimum Stored Energy Split Superconducting Magnet for 3T Mri-Pet Animal Imaging System Quang M. Tieng1, Viktor Vegh2 1Centre for Magnetic Resonance, University of Queensland, Brisbane, Queensland, Australia; 2Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia There exists an ever increasing need to design and build medical imaging systems that are capable of obtaining PET-MRI images in conjunction. This work describes minimum stored energy superconducting magnet coil arrangements for the purpose of a combined PET-MRI scanner. Two symmetric magnet coil configurations are used, similarly to the double doughnut systems, with space between them allowing for the insertion of a PET camera. The final design is capable of delivering 3T, which is appropriate for animal MRI. The results show that the minimum stored energy approach yields a compact configuration with a small footprint. 15:30 3951. Investigation of PET Count Rate Reduction During EPI Scan on an MR-PET Hybrid System Joachim Bernhard Maria Kaffanke1, Christoph Weirich1, Lutz Tellmann1, Karl-Joseph Langen1, Hans Herzog1, N. Jon Shah1,2 1Institute of Neurosciences and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich GmbH, 52425 Juelich, Germany; 2Faculty of Medicine, Department of Neurology, RWTH Aachen University, 52074 Aachen, Germany Hybrid MR-PET scanners offer great opportunities for the investigation of scientific questions and clinical diagnoses that are related to metabolism as well as function and structure of the brain. However, since the technology is new and still in development, it is of great importance to investigate how MR and PET systems influence each other in a combined scanner. Here, the effect of switched magnetic field gradients on the PET count rate is demonstrated and investigated. Tuesday 13:30-15:30 Computer 53 13:30 3952. Solving RF Interference for a Simultaneous PET/MRI Scanner Bo Joseph Peng1, Yibao Wu1, Jeffrey Walton2, Simon R. Cherry1 1Biomedical Engineering, University of California, Davis, Davis, CA, United States; 22NMR Facility, University of California, Davis, Davis, CA, United States From single PET module data acquisitions, we further demonstrate the effectiveness of concentric carbon fiber tubing as an excellent shielding material against 300 MHz RF. We also present a solution to reduce the 81 kHz RF interference generated by the MR gradient power supply. Ciprian Catana1, Andre van der Kouwe1, Thomas Benner1, Michael Hamm2, Christian J. Michel2, Matthias Fenchel2, Larry Byars2, Matthias Schmand2, Alma Gregory Sorensen1 1MGH, Radiology, A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States; 2Siemens Healthcare Attenuation correction is a required step not only for obtaining quantitative data, but also for performing meaningful qualitative image analysis. In order to achieve the necessary quantification for accurate quantitative neurological studies, three main components must be identified: water-based structures, bone tissue and air-filled cavities. DUTE sequences can potentially be used for bone/air segmentation. An MR-DUTE-based AC method could in principle provide accurate estimation of the radiotracer concentration in a particular voxel. Implementing an accurate MR-based AC will allow us take advantage of the improved quantitative capabilities of the combined MR-PET scanner. Joachim Bernhard Maria Kaffanke1, Irene Neuner1,2, Tony Stöcker1, Lutz Tellmann1, Karl-Joseph Langen1, Hans Herzog1, N. Jon Shah1,2 1Institute of Neurosciences and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich GmbH, 52425 Juelich, Germany; 2Faculty of Medicine, Department of Neurology, RWTH Aachen University, 52074 Aachen, Germany The new technology of hybrid MR-PET scanners offers great opportunities for the investigation of scientific questions and clinical diagnosis that are related to metabolism as well as function and structure of the brain. Despite the fact that the implementation of a PET ring inside the bore of a modern whole body MR scanner is demanding the benefits in terms of scan time reduction as well as spatial and temporal co-registration speak for the combination of these complementary technologies. In this feasibility study we demonstrate the simultaneous acquisition of FET-PET and fMRI data in human subjects with brain tumours. 15:00 3955. Improved PET Data Quantification in an Integrated Brain MR-PET Scanner Ciprian Catana1, Thomas Benner1, Andre van der Kouwe1, Michael Hamm2, Daniel B. Chonde1, Christian J. Michel2, Larry Byars2, Georges El Fakhri3, Nathaniel M. Alpert3, Matthias Schmand2, Alma Gregory Sorensen1 1MGH, Radiology, A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States; 2Siemens Healthcare; 3Radiology, MGH, Division of Nuclear Medicine & Molecular Imaging, United States Simultaneous MR-PET data acquisition immediately brings to mind the possibility of improving the performance of one instrument by using the information obtained from the other modality. A number of aspects have to be considered in PET for obtaining a correct quantitative measure of the activity concentration in a specific voxel. Examples include the attenuation and motion correction and the arterial input function estimation. The accuracy of these methods, in principle, could be improved by including the MR information. Wednesday 13:30-15:30 Computer 53 13:30 3956. Low-Noise Broadband Receive Amplifier for Real-Time Magnetic Particle Imaging - not available Ingo Schmale1, Bernhard Gleich1, Jürgen Rahmer1, Claas Bontus1, Jürgen Kanzenbach1, Joachim Schmidt1, Oliver Woywode2, Juergen Weizenecker3, Jörn Borgert1 1Philips Research Europe, Hamburg, Germany; 2Philips Medical Systems, Hamburg, Germany; 3University of Applied Sciences, Karlsruhe, Germany Magnetic particle imaging (MPI) is a new tomographic imaging modality first presented in 2005. It directly and quantitatively images iron-oxide nano-particle concentrations. By means of a broadband data acquisition, MPI also is very fast imaging modality allowing real-time volumetric imaging. After a motivation for broadband reception, this abstract describes the inherent challenges of and a technical solution for a low-noise broadband receive amplifier. This new amplifier is part of the current pre-clinical MPI demonstrator with ~12cm bore size. 14:00 3957. Narrowband MPI and Image Reconstruction for Small Animals Patrick Goodwill1, Steven Conolly2 1UC Berkeley / UC SF Joint Graduate Group in Bioengineering, Berkeley, CA, United States; 2Bioengineering, University of California, Berkeley, Berkeley, CA, United States Magnetic Particle Imaging (MPI) is a new imaging modality that directly detects SPIO nano-particles. Here we describe the construction and use of a small animal MPI system and mathematical methods for image reconstruction. 14:30 3958. Reducing Noise Artifacts in Intracranial EEG Within High Field MRI Giorgio Bonmassar1, Alexandra Golby2 1AA Martinos Center, Massachusetts General Hospital, Charlestown, MA, United States; 2Neurosurgery and Radiology, Brigham and Women’s Hospital, Boston, MA, United States A new type of MRI compatible intracranial electrode based on Polymer Thick Film (PTF) is presented and studied. When free electrons in the leads are exposed to Lorentz forces due to the motion of the leads in the static magnetic field (B0) results in induced current noise which makes the electroencephalogram impossible to interpret. The resistive leads were compared with metallic leads to estimate the Faradays induced current noise. In metallic materials the carrier density is very high (10 22 electrons/cm -3) compared to resistive leads. The results show that PTF resistive leads may reduce by four times the noise amplitude. 15:00 3959. Radio Frequency Shielding for a Linac-MRI System Michael Lamey1, Ben Burke1, Satyapal Rathee2,3, Nicola De Zanche2,3, Gino Fallone2,3 1Physics, University of Alberta, Edmonton, Alberta, Canada; 2Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada; 3Oncology, University of Alberta, Edmonton, Alberta, Canada This work illustrates that through proper shielding techniques, noise-free MR images can be acquired while a linac or MLC operate. Thursday 13:30-15:30 Computer 53 Shakil Ahmed Awan1, John McGinley2, Robert Dickinson, Ian Young3 1Bioengineering, Imperial College London, South Kensington, London, United Kingdom; 2Mechanical Engineering, Imperial College London; 3Electrical & Electronic Engineering, Imperial College London A technique has been developed, based on a planar B0-coil, to reduce artefacts in MRI caused by respiratory motion in patients. This should enable sub-millimetre resolution images to be detected using a MEMS microcoil. The microcoil, subject of a separate publication, was developed for catheter mounting and deployed in an endoscope for MR imaging of cholangiocarcinomas. The B0-coil has been designed to generate 1 mT, parallel to the main field of MRI scanner, with 80 Apk and to be homogenous to within ± 1% in a 150 mm DSV. 14:00 3961. MRI Motion Compensation by Ultrasound Navigators Benjamin Matthew Schwartz1, Nathan McDannold2 1Biophysics, Harvard University, Boston, MA, United States; 2Radiology, Harvard Medical School, Boston, MA, United States A well-known technique to reduce motion artifacts uses MR navigator echoes to track the position of the object being imaged, and compensates for the motion using this position information. We demonstrate an analogous technique, tracking motion using A-line images from a single ultrasound transducer. The ultrasound data can be analyzed in real time for prospective motion correction, or processed offline for retrospective correction. Ultrasound navigation allows the use of unmodified pulse sequences, with attendant advantages in acquisition speed, steady-state polarization, and reduced engineering requirements. Future development includes multidimensional tracking and supplying position data to non-MR equipment. Sjoerd Crijns1, Johan Overweg2, Bas Raaymakers1, Jan Lagendijk1 1Department of Radiotherapy, UMC Utrecht, Utrecht, Netherlands; 2Medical Imaging Systems, Philips Research Europe, Hamburg, Germany The performance of a split gradient coil for MRI guided radiotherapy is evaluated in terms of geometrical accuracy. 15:00 3963. Precise Co-Registration of SPECT and MRI for Small Animal Imaging Using a Common Animal Bed with External References:Visualization of Macrophage Distribution Within Inflammatory Lymph Nodes - not available Masayuki Yamaguchi1, Daisuke Suzuki1,2, Ryosuke Shimizu1,2, Ryutaro Nakagami1,3, Keisuke Tsuda1, Izumi Ogihara Umeda1, Yasuo Okuyama2, Kohki Yoshikawa2, Hirofumi Fujii1,4 1Functional Imaging Division, National Cancer Center Hospital East, Kashiwa, Chiba, Japan; 2Faculty of Health Sciences, Komazawa University, Setagaya, Tokyo, Japan; 3Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa, Tokyo, Japan; 4Institute for Bioinformatics Research and Development-Japan Science and Technology Agency, Chiyoda, Tokyo, Japan We tested the SPECT-MRI fusion technique to visualize regional lymph nodes involved in subacute inflammation arising from the lymphatic basin using a mouse model. Two to three weeks after the administration of Freund complete adjuvant to the foot pad, 99mTc phytate high-resolution SPECT images of the hind limb were obtained using a small animal SPECT scanner equipped with 4 detectors with multi-pinhole collimators. These SPECT images were merged with MR images to provid precise anatomical information. SPECT-MRI fusion images showed swollen popliteal lymph nodes and the accumulation of 99mTc at the periphery, suggesting the inhomogeneous distribution of macrophages within the swollen lymph nodes.
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