ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Electronic Poster Session • MR Engineering
3068 -3091 Hybrid Systems, Gradients & Monitoring
3092 -3115 Non-Array RF Coils, Materials & Other Hardware
3116 -3139 RF Coil Arrays
3164 -3187 RF Coil Arrays

Note: The videos below are only the slides from each presentation. They do not have audio.

Monday 1 June 2015
Exhibition Hall 14:15 - 15:15

  Computer #  
3068.   1 Integrated MRI-LINAC Radiotherapy Machine
Oliver Heid1, Michael Kleemann1, and Jürgen Heller1
1CT NTF HTC, Siemens AG, Erlangen, Bavaria, Germany

MRI is attractive as radio therapy guidance and control method due to its soft tissue contrast and its absence of X-ray radiation. We report on a proof of concept of an integrated radio-oncology LINAC treatment machine within an MRI system resulting in a reasonably compact and cost efficient device. Experimental prof is given which demonstrates operating a conventional 6 MeV LINAC within a conventional superconducting high field MRI magnet.

3069.   2 'Whole-Body PET/MR Imaging: Quantitative Evaluation of a Novel Model-based MR Attenuation Correction Method Including Bone
Daniel H Paulus1, Harald H Quick1,2, Matthias Fenchel3, Christian Geppert3, David Faul4, Yiqiang Zhan5, Fernando E Boada6,7, Kent L Friedman6, and Thomas Koesters6,7
1Institute of Medical Physics, University of Erlangen-Nürnberg, Erlangen, Germany, 2High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany, 3Siemens AG Healthcare, Erlangen, Germany, 4Siemens AG Healthcare, New York, NY, United States, 5Siemens AG Healthcare, Malvern, PN, United States, 6NYU Langone Medical Center, Center for Biomedical Imaging, Department of Radiology, New York, NY, United States, 7NYU Langone Medical Center, Center for Advanced Imaging Innovation and Research, CAI2R, New York, NY, United States

In whole-body hybrid PET/MR imaging, bone is currently disregarded in attenuation correction. For head imaging, several approaches have been proposed to consider bone, but yet, not assigned to whole-body imaging. A novel attenuation correction approach for hybrid PET/MR imaging is presented and evaluated on 19 patients that combines the routine Dixon-based soft tissue segmentation with model-based bone estimation for whole-body imaging. As a standard of reference, CT images of each patient were non-rigidly registered to the MR images. It is shown that the new method significantly improves the PET quantification in bony tissue, bone lesions, and tissue close to bone.

3070.   3 Clinical MR-Linac System
Johan Overweg1, Falk Uhlemann1, Phil Jonas2, Thomas Amthor1, Peter Forthmann2, Panu Vesanen3, Tero Virta3, Christopher Busch3, and Kevin Brown4
1Philips Innovative Technologies, Hamburg, Germany, 2Philips Healthcare, Latham, New York, United States, 3MR therapy, Philips Healthcare, Vantaa, Finland, 4Elekta Limited, Crawley, United Kingdom

A concept for a real-time MR-guided radiotherapy system has been industrialized to make it suitable for clinical use.

3071.   4 Optimisation of a 32-channel Resonator for Simultaneous PET/MRI of the Head at 3.0 Tesla: Material Selection and Performance Testing
Adam Farag1,2 and Jean Theberge3,4
1Ceresensa Inc, London, Ontario, Canada, 2Western University, London, Ontario, Canada, 3Lawson Health Research Institute, Ontario, Canada,4Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada

Positron emission tomography and magnetic resonance imaging systems (PET/MRI) has been recently developed for human imaging, harnessing the powers of morphology and function. Yet, such technology is still in need for complementary tools, such as, dedicated radiofrequency resonators. In this work an approach is presented to optimise a dedicated multi-channels head resonator. The resonator will be used to acquire simultaneously PET/MRI images. Aiming to develop objective diagnostic methods to discriminate unipolar from bipolar using combined serotonin PET, resting state fMRI and blood oxygenation level dependent fMRI.

3072.   5 Zero TE based PET attenuation correction in the head
Florian Wiesinger1, Anne Menini1, Sangtae Ahn2, Lishui Cheng2, Gaspar Delso3, Sandeep Kaushik4, Ravindra Manjeshwar2, and Dattesh Shanbhag4
1GE Global Research, Munich, Germany, 2GE Global Research, Niskayuna, NY, United States, 3GE Healthcare, Zurich, Switzerland, 4GE Global Research, Bangalore, India

PET/MR is a novel hybrid imaging modality which promises to influence radiology in the near and long-term future. Despite dedicated and focused research efforts, MR-based PET attenuation correction (MR-AC) as required for quantitative PET is still considered challenging; especially when compared to PET/CT. A particular challenge is the correct characterization of bone; i.e. the human tissue with the highest PET attenuation value but which is difficult to capture by MR. Recently a novel zero TE (ZT) based method has been described for fast and reliable bone depiction and segmentation. Here we investigate the feasibility of ZT-based PET attenuation correction (ZT-AC) in the head.

3073.   6 MR driven PET-attenuation correction in presence of metal implants using anatomy context driven decisioning - permission withheld
Dattesh D Shanbhag1, Sandeep S Kaushik1, Sheshadri Thiruvenkadam1, Florian Wiesinger2, Sangtae Ahn3, Rakesh Mullick4, and Ravindra M Manjeshwar5
1Medical Image Analysis Laboratory, GE Global Research, Bangalore, Karnataka, India, 2Diagnostics & Biomedical Technology Laboratory, GE Global Research, Garching, Bavaria, Germany, 3Functional Imaging Laboratory, GE Global Research, Niskayuna, NY, United States, 4Diagnostics & Biomedical Technologies, GE Global Research, Bangalore, Karnataka, India, 5X-ray & Functional Imaging, GE Global Research, Niskayuna, NY, United States

Correction of metal implant areas in MRAC map is considered an important unmet need to guarantee accurate and robust MR-based PET-AC. We demonstrate that use of spatially adaptive phase field based approach and anatomy context driven decisioning can help address metal implant related issues in tissue segmentation and consequently result in improved fidelity of PET reconstruction. Overall, the presented method will allow for more robust and accurate MR-AC and accordingly PET quantification in the presence of metallic implants.

3074.   7 MR Guided Motion Correction for Yttrium 90 Imaging using a Simultaneous PET/MRI Scanner
Mootaz Eldib1,2, Niels Oesingmann3, David Faul3, Jason Bini1,2, Lale Kostakoglu4, Karin Knesaurek4, and Zahi A. Fayad1
1TMII, Ichan School of Medicine at Mount Sinai, New York, NY, United States, 2Biomedical Engineering, City College of New York, New York, NY, United States, 3Siemens Healthcare, New York, NY, United States, 4Radiology, Ichan School of Medicine at Mount Sinai, New York, NY, United States

Yttrium 90 radio-embolization is a therapeutic procedure that delivers radiation directly to hepatic tumors. Post-procedure PET imaging is a useful tool in detection of shunting to other organs, and in dose calculations and quantification. Both of these applications would suffer from errors due to breathing motion and thus motion correction is critical. In this study an MR-based motion correction approach is developed and implemented using a simultaneous PET/MRI scanner. Phantom and human data are presented.

3075.   8 A new unilateral breast specific coil design and dual-modality interface configuration for MR/scintimammography
Jaedu Cho1, Seunghoon Ha1, Alex Luk1, Farouk Nouizi1, Orhan Nalcioglu1, Gultekin Gulsen1, and Ming-Ying Su1
1Center for Functional Onco-Imaging, University of California Irvine, Irvine, CA, United States

MR/scintimammography (MR/SMM) is a promising high sensitivity and high specificity dual-modality imaging system for the diagnosis of breast cancer. We present a new unilateral breast specific coil and a novel dual-modality interface configuration for MR/scintimammography. The new two channel unilateral coil consisted of a quadrature solenoid coil and a quadrature saddle coil. These two channel coils are specifically designed not only to obtain high sensitivity breast MR imaging, but also to allow simultaneous MR/SMM imaging. The performance of this new system configuration is compared to a commercial breast coil.

3076.   9 Design of a Whole-Body Radio Frequency Coil for image-guided radiotherapy treatment in a MRI-LINAC system
Aurelien Destruel1, Ewald Weber1, Ivan Hughes1, Yu Li1, Feng Liu1, and Stuart Crozier1
1School of ITEE, University of Queensland, Brisbane, Queensland, Australia

In this work, a RF transmit volume coil was designed to work in a MRI-Linac. Because of the novelty of this approach and the specific geometry of the magnet, specific constraints had to be accommodated. To ensure the reliability of the design, the behaviour of the coil was modelled in an electromagnetic simulation, and a prototype was built in a mock-up of the magnet. Results converged to show that the homogeneity of the transmit field in the DSV are very uniform.

3077.   10 Feasibility of 18F-FDG Radio-Tracer Dose Reduction in Simultaneous Carotid PET/MR Imaging
Mootaz Eldib1,2, Jason Bini1,2, Olivier Lairez1,2, Zahi A Fayad1,2, and Venkatesh Mani1,2
1Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States, 2Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, NEW YORK, New York, United States

PET/CT is typically used to evaluate vascular inflammation. An advantage of using PET/MR compared to PET/CT is that it delivers less ionizing radiation. Further reduction in the delivered dose of radiotracers using simultaneous PET/MR can be achieved by matching the duration of the PET acquisition to that of MR (which is generally longer in duration than CT) and thus achieving good image quality. In this study, we evaluate the feasibility of low dose, long duration 18F-FDG PET imaging using a simultaneous PET/MR scanner.

3078.   11 Whole-Body PET-MR Including DWI, T2w, and Gadofosveset-enhanced T1w Sequences: Evaluation of MR Performance Compared to PET-CT and Relative Benefits Provided by Each Sequence
Piotr Obara1, Andreas Loening1, Valentina Taviani1, Andrei Iagaru1, Brian Hargreaves1, and Shreyas Vasanawala1
1Radiology, Stanford Hospital, Stanford, California, United States

Diffusion-weighted (DW), T2-weighted, and gadofosveset-enhanced T1-weighted images from 14 whole body PET-MR exams were assessed by 2 radiologists for presence of malignant disease as well as lesion conspicuity and delineation. Compared to PET-CT, MR showed good sensitivity and specificity on a per-organ basis but only fair specificity on a per-patient basis due to false positive findings in osseous structures. Lesion conspicuity was rated best on DW images, particularly in osseous structures. The relatively lower conspicuity on post-contrast images could have been in part due to suboptimal lesion enhancement with gadofosveset.

3079.   12 MR Performance Evaluation of a PET/MR With SiPM Based Time of Flight PET Detectors
Mohammad Mehdi Khalighi1, Gaspar Delso2, Sri-Harsha Maramraju3, Greg Zaharchuk4, and Gary Glover4
1Applied Science Lab, GE Healthcare, Menlo Park, CA, United States, 2Applied Science Lab, GE Healthcare, Zurich, Switzerland, 3PET/MR Engineering, GE Healthcare, Waukesha, WI, United States, 4Radiology Dep., Stanford University, Stanford, CA, United States

The MR performance of an investigational hybrid PET/MR system is compared to a comparable wide-bore MR machine. We show that the MR performance is not significantly compromised after PET ring insertion. It is also shown that PET acquisition itself has a very small effect (3% SNR drop). Because of the smaller diameter, the PET/MR body coil SNR is higher and demonstrates 30% increased peak B1+. The only significant tradeoff between PET/MR and a wide-bore MR is the bore size (60cm vs. 70cm).

3080.   13 MR performance of an MR-Linac prototype
Panu Vesanen1, Jukka Tanttu1, Juha Oila1, Tiina Näsi1, Annemaria Halkola1, Tero Virta1, Falk Uhlemann2, Johan Overweg2, and Jarmo Ruohonen1
1MR Therapy, Philips Healthcare, Vantaa, Finland, 2Philips Innovative Technologies, Hamburg, Germany

In treatment of cancer by conventional radiotherapy, motion of the target and nearby organs limits the accuracy of the treatment delivery. A combined MRI and linear accelerator system (MR-Linac) aims to reduce these inaccuracies by providing image guidance with excellent soft-tissue contrast. In this abstract, MR performance of an industry-built 1.5T MR-Linac prototype was evaluated by comparing the image quality to that obtained with a commercially available 1.5T scanner. Pelvis, abdomen, and head & neck anatomies of 20 healthy volunteers were studied. No significant differences in the image quality or SNR were found.

3081.   14 Dynamic Brain PET/MR using TOF Reconstruction
Mohammad Mehdi Khalighi1, Gaspar Delso2, Sri-Harsha Maramraju3, Michel Tohme3, Gary Glover4, and Greg Zaharchuk4
1Applied Science Lab, GE Healthcare, Menlo Park, CA, United States, 2Applied Science Lab, GE Healthcare, Zurich, Switzerland, 3PET/MR Engineering, GE Healthcare, Waukesha, WI, United States, 4Radiology Dep., Stanford University, Stanford, CA, United States

In a functional PET/MR study, temporal resolution of PET images is lower than that of MR due to SNR limitation. Time-of-flight (TOF) reconstruction can be used to increase PET images’ SNR and therefore increase the temporal resolution. Five patients were scanned on an investigational simultaneous TOF-enabled PET/MR scanner and PET images were reconstructed with and without TOF. TOF reconstruction showed an SNR improvement of 5-45% (25±10%) compared to non-TOF reconstruction. With this additional SNR gain, frame durations as short as 30s were possible while preserving reasonable image quality. Such short frames may be used to increase the temporal resolution of dynamic brain studies using simultaneous PET/MR imaging.

3082.   15 Stress and Strain Sensitivity Study of 1.5T Conduction Cooled MgB2 Magnet Design.
Abdullah Al Amin1, Tanvir Baig2, Zhen Yao2, and Michael A Martens2
1Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, Ohio, United States, 2Department of Physics, Case Western Reserve University, Cleveland, Ohio, United States

Ever increasing liquid helium (LHe) price has pushed researchers to design background magnets that could operate in conduction cooling mode. High Tc superconductor e.g. MgB2 is a promising candidate for conduction cooled magnet. But high strain sensitivity of MgB2 wire could be a limiting factor in designing a whole body MRI magnet of 1.5T or higher. In this work, strain sensitivity of an optimized 1.5T conduction cooled MgB2 MRI magnet is numerically studied. The stress and strains behavior of the design shows viability of building such conduction cooled magnet.

3083.   16 A 24-channel shim array for real-time shimming of the human spinal cord: Characterization and proof-of-concept experiment
Ryan Topfer1, Kai-Ming Lo2, Karl Metzemaekers2, Donald Jette2, Hoby P. Hetherington3, Piotr Starewicz2, and Julien Cohen-Adad1,4
1Institute of Biomedical Engineering, Ecole Polytechnique de Montréal, Montreal, QC, Canada, 2Resonance Research Inc., Billerica, MA, United States,3Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 4Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montreal, QC, Canada

A novel shim system is introduced for the purpose of real-time shimming in spinal imaging to compensate for respiratory-related distortions of the main field. The 24 independent, rectangular planar shim coils are embedded within the patient bed table, in close proximity to the spine of the scanned subject. Preliminary calibration and “proof of concept” phantom experiments are described. Compared to the unshimmed case, the standard deviation of the field inhomogeneity, as calculated over 1.1 L volumes of interest, was reduced by over 30 %.

3084.   17 Simultaneous EEG-fMRI: evaluating the effect of the EEG cap cabling configuration on the gradient artefact.
Muhammad E H Chowdhury1, Karen J Mullinger1,2, and Richard Bowtell1
1SPMIC, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom, 2BUIC, School of Psychology, University of Birmingham, Birmingham, United Kingdom

EEG data recorded during fMRI are compromised by large gradient artefact (GA) voltages. The GA is usually corrected using average artefact correction; requiring the amplifier to have a large enough dynamic range to characterise the artefact voltages. Here we re-designed the EEG cap-cable configuration so that the GA induced in the 1 m ribbon cable by an AP gradient partially cancels that induced in the EEG cap and head. We demonstrate that the range and amplitude of the GA can be significantly reduced by cap-cable re-wiring, allowing recording at higher EEG bandwidths or increased achievable image resolution without saturation.

3085.   18 An improved design of multi-channel switching circuit for matrix gradient coil
Huijun Yu1, Frank Huethe2, Sebastian Littin1, Kelvin Layton1, Stefan Kroboth1, Feng Jia1, Jürgen Hennig1, and Maxim Zaitsev1
1Dept. of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, BW, Germany, 2Dept. of Clinical Neurology and Neurophysiology, University of Freiburg, Freiburg, BW, Germany

An updated multi-channel switching circuit for matrix gradient coil is presented in this work to reduce the total number of gradient amplifiers and provide more flexibility to generate the customized current patterns. The bridge switches and interconnection switches are used to dynamically configure the current path of coil elements during the pulse sequence to generate the specific current pattern. The amplifier selection switches are used for dynamically defining different channels of the current path during the experiment (the number of channels of current path is equal to the number of used gradient power amplifiers).

3086.   19 Virtual Phantom (ViP) MRI: a method to generate virtual phantoms that mimic water-fat systems
Roberto Salvati1,2, Eric Hitti1,2, Jean-Jacques Bellanger1,2, Herve Saint-Jalmes1,2, and Giulio Gambarota1,2
1Université de Rennes 1, LTSI, Rennes, France, 2INSERM, UMR 1099, Rennes, France
Virtual Phantom (ViP) for Magnetic Resonance Imaging (MRI) is a method to generate reference signals, without using physical objects, using an external waveform generator and an RF coil. In a previous work it was shown that ViP MRI could substitute agar gel phantoms, using magnitude images. The aim of the current study was to test the feasibility of the ViP MRI method to generate magnitude and phase images that mimic water-fat systems. To this aim, multi gradient-echo magnitude and phase images of ViPs and physical phantoms were acquired for IDEAL (Iterative Decomposition with Echo Asymmetry and Least squares estimation) reconstruction.

3087.   20 Peripheral Nerve Stimulation Considerations in the Presence of the Metallic Objects
Vahid Ghodrati1, Niloufar Zakariaei1, and Abbas Nasiraei Moghaddam1,2
1BME, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Tehran, Iran, 2School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran

Foreign objects with high conductivity can intensify and concentrate the induced eddy currents from the gradient switching. These concentrated currents in turn may cause PNS during MR-imaging and potentially result in a mild to intolerable discomfort for the patient especially when the foreign object is in the vicinity of sensible locations. The maximum limit for applied gradient intensity in different gradient switching times has been modified to guarantee the safe mode in the presence of metallic objects. We showed that the conductive materials mostly affect the small rise times as the modifies limit is less sensitive to gradient rise time compared to IEC standard.

3088.   21 Dynamic off-resonance magnetic field monitoring and correction using proton field probes
Ying-Hua Chu1, Yi-Cheng Hsu1, Shang-Yueh Tsai2, Wen-Jui Kuo3, and Fa-Hsuan Lin1
1Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan, 2National Chengchi University, Taipei, Taiwan, 3National Yang Ming University, Taipei, Taiwan

Here we develop a 10-channel field probe system using 1H as the NMR signal source to monitor the magnetic field. The field probe is decoupled from the subject by interleaving the field probe measurement and subject imaging. Specifically, field probe NMR signal was measured at high spatial frequency k-space point in order to minimize the NMR signal from the subject. Empirical data showed successful monitoring of respiratory and cardiac cycles. We can track 2D field drifting with 0.1 s temporal resolution and use this information to improve the time-domain SNR (tSNR) of dynamic spiral imaging by 137 %.

3089.   22 Accurate Vibroacoustic Simulations in High Performance Gradient Coils
Simone Angela Winkler1, Trevor P Wade2, Andrew Alejski2, Charles McKenzie2, and Brian K Rutt1
1Dept. of Radiology, Stanford University, Stanford, CA, United States, 2Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada

We present a comprehensive modeling approach for acoustic noise in MR gradient coils that includes previously neglected but essential factors. Our simulation environment is the most complete developed to date for vibroacoustic gradient coil simulations, incorporating such features as full structural-acoustic coupling. We have used this new simulation environment to model realistic head and body gradient coils, and have used experimental measurements to demonstrate accurate prediction of acoustic and vibration spectra and spectrally averaged levels. This new simulation environment has great potential for the accurate prediction and ultimately reduction of acoustic and vibration levels in high performance gradient systems.

3090.   23 The Automatic Placement of Cooling Pathways for MRI Gradient Coils Using Path Finding Algorithms
Elliot Smith1, Fabio Freschi1,2, Maurizio Repetto2, and Stuart Crozier1
1School of ITEE, University of Queensland, Brisbane, Queensland, Australia, 2Department of Energy, Politecnico di Torino, Torino, Italy

The thermal performance of MRI hardware is critical to the safe and efficient operation of these devices. Placement of cooling pipes can help to transport heat away from the system. Placing this pipes algorithmically can lead to an efficient cooling system based on thermal simulation and path finding algoithms.

3091.   24 Design of a shielded coil element of a matrix gradient coil
Feng Jia1, Sebastian Littin1, Kelvin Layton1, Stefan Kroboth1, Huijun Yu1, Jürgen Hennig1, and Maxim Zaitsev1
1Dept. of Radiology, University Medical Center Freiburg, Freiburg, BW, Germany

Spatial encoding with nonlinear magnetic fields (SEMs) has raised increasing interest in the past few years. Matrix coils consisted of multiple coil elements appear to offer a high flexibility in generating customized SEMs and are particularly promising for localized high resolution imaging applications such as PatLoc . However, existing coil elements of those matrix coils cannot lead to an optimal performance according to the measure of matrix coils. In this work, an optimization problem is formulated that results in optimal designs of novel, high-performance coil elements of a matrix coil. Two parameters are proposed to assess the performance of different coil elements. The results are tested and the analysis reveals novel features of coil element designs.

Monday 1 June 2015
Exhibition Hall 14:15 - 15:15

  Computer #  
3092.   25 RF Dipole Coil with Novel Slotted Shielding Plate Achieving an Improved B1 Distribution for 7 T MRI - permission withheld
Zhichao Chen1,2, Mahdi Abbasi1, Klaus Solbach2, Daniel Erni1, and Andreas Rennings1
1General and Theoretical Electrical Engineering (ATE), Faculty of Engineering, University of Duisburg-Essen, Duisburg, NRW, Germany, 2High Frequency Engineering (HFT), Faculty of Engineering, University of Duisburg-Essen, Duisburg, NRW, Germany

A dipole coil with miniaturized eigen-resonant shielding plate at 300 MHz is presented. The size reduction is done by etching several slots in the shielding plate and enclosing the slotted sections with high-dielectric substrates. The dipole element with proposed slotted shielding plate exhibits an improvement in terms of B1 homogeneity and penetration depth comparing to the ordinary (unslotted) case. Single element and multi-channel setups loaded by a homogeneous phantom are utilized to evaluate the proposed approach. Without diminishing the merit of eigen-resonant shielding plate, the presented dipole coil has more placement flexibility for certain applications due to the size reduction.

3093.   26 Inductively Coupled Planar TX Coils: Analysis of B1+ Efficiency and SAR Performance
Johanna Schöpfer1,2, Klaus Huber2, Stephan Biber3, Markus Vester3, Sebastian Martius2, and Martin Vossiek1
1LHFT, University of Erlangen-Nuremberg, Erlangen, Germany, 2Siemens AG, Corporate Technology, Erlangen, Germany, 3Siemens AG, Healthcare, Erlangen, Germany

High SAR values can increase imaging time, especially if very high B1+ fields are required. In this study, potential benefits of inductively coupled planar loop antennas, designed to focus the transmit field, are evaluated and compared to the transmit characteristics of the body coil. It shows that the inserted loop leads to reduced power requirements and SAR without significantly decreasing B1+ homogeneity in the defined ROI, relative to standard excitation with the body coil.

3094.   27 Tackling the Challenges of Imaging the Infant Brain in a Dedicated Neonatal Coil
Emer Hughes1, Tobias Winchmann2, Laurent Mager3, Francesco Padormo4, Hutter Jana4, Julia Wurie1, Matthew Fox1, Maryanne Sharma1, David Edwards1, Andrew Kapetanakis1, Alessandro Allievi5, and Joseph Hajnal4
1Centre for the developing brain, Kings College London, London, London, United Kingdom, 2Rapid biomedical engineering, Germany, 3Peraltec AG, Switzerland, 4Division of imaging science and biomedical engineering, Kings College London, London, London, United Kingdom, 5Imperial College London, London, United Kingdom

Optimal performance for neonatal brain imaging requires the receive coil to be as close fitting as possible, but this creates challenges for patient handling. Here, we developed a joint design of a 32 channel neonatal array and a baby transport and positioning system intended for examining babies up to 44 weeks at time of scan. The purpose of this was to implement a system to consistently gain high image quality in preparation for the developing Human Connectome Project (dHCP).

3096.   29 High-precision Magnetic Susceptometry Applied to 3D-printed RF Coil Construction
R. Adam Horch1,2 and John C Gore1,2
1Department of Radiology & Radiological Sciences, Vanderbilt University, Nashville, TN, United States, 2Vanderbilt University Institute of Imaging Science, Nashville, TN, United States

An apparatus capable of high precision (< 1 ppb) measurements of magnetic susceptibility has been developed with broad potential in the characterization of materials for MR instrumentation. Measurements of 3D-printed materials relevant to RF coil construction have been performed. For example, 3D-printed ultem differs in susceptibility from water, despite pure ultem’s excellent match. Poly(methyl methacrylate) and polycarbonate-based 3D-printed materials offer alternatives which closely match water’s magnetic susceptibility.

3097.   30 Ink-jet printing enables maskless electroplating mould patterning for rapid MRI coil fabrication
Markus V. Meissner1, Nils Spengler1, Dario Mager1, Jens Höfflin1, Peter T. While1, and Jan G. Korvink1
1Department of Microsystems Engineering - IMTEK, University of Freiburg, Freiburg, BW, Germany

We introduce a novel micro-electroplating process based on ink-jet printed conductive structures, to define high-aspect-ratio MRI field coils. To structure electrically conductive tracks, silver nano particle based ink is printed directly on permanent dry film resist. In this process, molds for electroplating are patterned into thick-film photo-definable resist via backside exposure where our printed structures serve as both the shadow mask for the mold, and the seed layer for the electroplating. Our process is particularly suitable for the rapid manufacture of small planar TxRx, shim and gradient coils.

3098.   31 Baluned-Hairpin-(BHP)-Resonator for Field Monitoring
Thomas Riemer1
1Insitute for Medical Physics and Biophysics, University of Leipzig, Leipzig, Saxony, Germany


3099.   32 Comparison of different simulation methods regarding their feasibility for MRI coil design
Sebastian Martius1, Johanna Schöpfer1,2, Andreas Fackelmeier1, and Klaus Huber1
1Siemens AG, Coporate Technology, Erlangen, Germany, 2LHFT, University of Erlangen-Nuremberg, Erlangen, Germany

Loop antenna arrays are the major components for reception in magnetic resonance imaging systems. Typically 3D full wave field calculation software is used for calculation of the corresponding s-Parameters and field distribution of these loop antennas. In the following paper different simulation methods are compared, including various meshing techniques in time and frequency domain simulations, regarding their suitability of accurately calculating a more complex antenna structure.

3100.   33 The Distributed Inductance Electric Dipole Antenna
Graham C Wiggins1,2, Karthik Lakshmanan1,2, and Gang Chen1,3
1The Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, Newyork, NY, United States, 2The Center for Advanced Imaging Innovation and Research (CAI2R),Department of Radiology, New York University School of Medicine, Newyork, NY, United States, 3The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, Newyork, NY, United States


3101.   34 A Cryogenic Solenoid Transmit/Receive Coil Cooled with Liquid Nitrogen for Sodium Imaging at 11.7 T
Kuan Zhang1, Lian Xue1, Guangfu Xu2, Zungang Liu2, Erzhen Gao2, Q.Y. Ma2, Nikolaus M Szeverenyi3, and Graeme Bydder3
1Time Medical Systems, Inc, San Diego, CA, United States, 2Time Medical Systems, Inc, China, 3University of California, San Diego, CA, United States

A cyrogenic solenoid transmit/receive coil resonating at 132 MHz for sodium MRI (11.7T) was constructed and tested at liquid nitrogen temperature. The tuning circuit is kept outside the cryostat at room temperature for easy access. The resonant frequency was tunable over a 250 kHz range, allowing compensation for various sample loadings. Images were acquired on a 3 mm thick anatomical human patella specimen using a Bruker 11.7T animal MRI scanner, both with this cryo-coil and a room temperature coil of identical structure for comparison. A 70% SNR improvement was obtained. The coil package is small and convenient for commercial use.

3102.   35 Evaluation on coupling strategies for ultra-high field MRI probe made of cylindrical dielectric resonator
Rui Liu1, Wei Luo2, Thomas Neuberger3,4, and Michael Lanagan1,2
1Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania, United States, 2Material Research Insititute, Pennsylvania State University, University Park, Pennsylvania, United States, 3Huck Institute of Life Science, Pennsylvania State University, University Park, Pennsylvania, United States, 4Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States

In this study, different coupling methods for a cylindrical dielectric resonator operating in TE01δ mode were investigated and compared at 14T. The best coupling method was selected based on the analysis of the scattering parameters. It yielded a Q-factor around 716.2 and S21 value of -9.20 dB. The relationship between different Q-factors and their effects on S21 were discussed. The results from this study will be useful for the new designs on MRI probe head made of cylindrical dielectric resonators.

3103.   36 Evaluation of Displacement Currents and Conduction Currents in a Close Fitting Head Array with High Permittivity Material
ChristopherM. M. Collins1,2, Giuseppe Carluccio1,2, Manushka Vaidya1,2, Gillian Haemer1,2, Riccardo Lattanzi1,2, Graham C. Wiggins1,2, Daniel K. Sodickson1,2, and Qing X. Yang3
1Center for Advanced Imaging Innovation and Research (CAI2R), New York University School of Medicine, New York, NY, United States, 2Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, United States, 3Center for NMR Research, Penn State College of Medicine, Hershey, PA, United States

While most work with high permittivity materials (HPMs) in MRI has been focused on improving SNR or transmit efficiency for a relatively small region within a much larger coil or array, more recent work demonstrates that HPMs can also improve performance of smaller coils very near the subject, as well as arrays of such coils for the entire region of the anatomy they encompass. Here we illustrate differences in the nature of coil functionality when HPMs are present with graphical plots and analysis of both conduction currents and displacement currents.

3104.   37 Changes in neighbor and next-nearest-neighbor coupling of transmit/receive arrays in the presence of close-fitting high permittivity materials
Gillian G Haemer1,2, Manushka V Vaidya1,2, Christopher M Collins1,2, and Graham C Wiggins1
1The Center for Advanced Imaging Innovation and Research, and the Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, 2The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States

The use of high permittivity materials (HPMs) can improve coil performance at ultra high field. Much recent experimental work performed with HPMs has been done with prefabricated coils and/or standardized clinical coils, built without the use of dielectric materials in mind. However, close-fitting transmit arrays are at risk of interacting closely with the HPM, and therefore having their performance in the presence of the HPM affected. Here we explore how HPMs proximal to a set of three geometrically decoupled coils affect their performance and decoupling.

3105.   38 SAR Reduction in RF Shimming through the use of High Permittivity Materials: approach towards the Ultimate Intrinsic SAR
Gillian G Haemer1,2, Manushka V Vaidya1,2, Christopher M Collins1,2, Daniel K Sodickson1,2, Graham C Wiggins1, and Riccardo Lattanzi1,2
1The Center for Advanced Imaging Innovation and Research, and the Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, 2The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States

Appropriate high-permittivity, low-conductivity materials (HPM) placed between the RF coil and the sample can provide performance improvement in both transmission and reception. We employed a simulation framework based on dyadic Green’s functions for multi-layered spherical geometries to analyze how HPMs affect the tradeoff between excitation homogeneity and global Specific Absorption Rate (SAR) for RF shimming at 7T, using transmit arrays with an increasing number of elements and Ultimate Intrinsic SAR as a reference. We generated L-curves showing ultimate performance could be approached with a relatively small number of transmit elements by optimizing the relative permittivity of the HPM layer.

3106.   39 Improving B1+ Uniformity Using Segmented Dielectric Pads
Aurelien Destruel1, Jin Jin1, Feng Liu1, Mingyan Li1, Ewald Weber1, and Stuart Crozier1
1School of ITEE, University of Queensland, Brisbane, Queensland, Australia

This study presents a novel method of improving dielectric shimming. In contrast to conventional approach where large pads are generally used, narrow segmented pads are used in the current study. Additionally, the combination of permittivity values for all segments is optimised. The simulation results show that, for 7T head imaging, using eight narrow pads with optimised permittivity distribution constraints the displacement currents to the longitudinal direction, to most effectively produce transmit magnetic field. Furthermore, the uniformity of the transmit magnetic field has been significantly improved. By increasing the degrees-of-freedom in regulating the displacement current distribution, the proposed approach provides a new perspective in dielectric shimming.

3107.   40 The basis functions: a novel approach for electromagnetic fields evaluations for any matching and coupling conditions
Gianluigi Tiberi1,2, Nunzia Fontana3, Riccardo Stara4, Alessandra Retico5, Agostino Monorchio3, and Michela Tosetti2
1Imago7, Pisa, PI, Italy, 2IRCCS Stella Maris, Pisa, PI, Italy, 3Dipartimento di Ingegneria dell’Informazione, Pisa, PI, Italy, 4Dipartimento di Fisica, Pisa, PI, Italy, 5Istituto Nazionale di Fisica Nucleare, sezione di Pisa, Pisa, PI, Italy

A procedure for evaluating RF electromagnetic fields in anatomical human models for any matching and coupling conditions is introduced. The procedure resorts to the extraction of basis functions: such basis functions, which represent the fields produced by each individual port without any residual coupling, are derived through an algebraic procedure which uses the S parameter matrix and the fields calculated in one (only) full-wave simulation. The basis functions are then used as building-blocks for calculating the fields for any other S parameter matrix.

3108.   41 RF Safety Validation of High Permittivity Pads at 7 Tesla
Wyger Brink1, Yacine Noureddine2, Oliver Kraff2, Andreas K. Bitz2,3, and Andrew Webb1
1Radiology, Leiden University Medical Center, Leiden, Netherlands, 2Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany, 3Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

Electric near-field measurements confirm that the electric fields within the phantom are very well be affected by the dielectric pads. The data presented here indicate an agreement between simulations and measurements of electric and magnetic fields in the order of ~10%. This means that realistic scenarios can be evaluated with this error margin to provide SAR estimates for using pads in vivo.

3109.   42 Ideal current patterns correspond to larger surface coils with use of high permittivity materials
Manushka V Vaidya1,2, Gillian G Haemer1,2, Giuseppe Carluccio1, Dmitry Novikov1,2, Daniel K. Sodickson1,2, Christopher M. Collins1,2, Graham C. Wiggins1,2, and Riccardo Lattanzi1,2
1Center for Advanced Imaging Innovation and Research, and Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, 2Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States

Ideal current patterns maximize the SNR for a position within the imaging sample. Our work demonstrates that in imaging a central voxel, addition of a dielectric layer surrounding a spherical sample results primarily in a phase lag in the ideal current patterns corresponding to the additional propagation time through the layer. For an off-center voxel, the ideal current pattern covers a larger area when the dielectric layer is present, indicating that larger sized coils are optimal in this case. Our results provide an understanding of electromagnetic field behavior with dielectric materials, and provide a method to predict optimal coil design.

3110.   43 Optimal Permittivity of Dielectric Liners and their Effects on Transmit Array Performance
Atefeh Kordzadeh1 and Nicola DeZanche2
1Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada, 2Department of Medical Physics, Cross Cancer Institute and University of Alberta, Edmonton, Alberta, Canada

Dielectric pads are used as an effective method to increase the signal locally and also increase the RF field homogeneity in high-field MRI. Here we investigate the effect of dielectric liners of various permittivities on the transmit performance of a head coil array at 4.7T. Results show that field homogeneity and sensitivity are competing goals and a compromise is needed based on the application. An optimal value for permittivity is found which is lower than values which are commonly used in the literature.

3111.   44 Influence of metamaterial insert to cylindrical RF coil array in human knee MR imaging at 1.5T
Xiaoqing Hu1, Chunlai Li2, Hongyi Wang1, Xiaoliang Zhang3, Xin Liu1, Hairong Zheng1, Lin Luan2, and Ye Li1
1Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology of Chinese Academy of Sciences, Shenzhen, Guangdong, China, 2ShenzhenKey Laboratory of Optical and Terahertz Meta-RF, Kuang-Chi Institute of Advanced Technology, Shenzhen, Guangdong, China, 3Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, United States

Influence of metamaterial insert to cylindrical RF coil array in human knee MR imaging at 1.5T

3112.   45 Development of low field MRI system running on the same magnetic circuit used for 750 MHz CW EPR imaging system
Hideo Sato-Akaba1 and Hiroshi Hirata2
1Department of Systems Innovation, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan, 2Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido, Japan

EPR imaging allows visualizing free radicals in small animals and gives information of redox status in various tissues. However, the determination of the position is difficult due to the lack of anatomical information. So far to solve this problem, co-registration of an EPR image and a high field MRI image has been applied. However, the cost of the high field MRI system may be obstacle for many researchers to access this method. The purpose of the present work was developing a compact low field MRI system running on a same magnetic circuit used for a 750 MHz EPR imaging system.

3113.   46 SpinoTemplate: A System for MR-Guided Spinal Cellular Therapeutics Injections
Alexander Squires1, John Oshinski2, Jason Lamanna2, and Zion Tsz Ho Tse1
1College of Engineering, The University of Georgia, Athens, GA, United States, 2Department of Radiology, Emory University, Atlanta, GA, United States

A MRI-guided needle positioning system was developed to provide a less invasive surgical method for delivering cellular therapeutics to the spinal cord of swine subjects used in ALS studies. The resulting system is capable of delivering 2mm targeting accuracy along with ease of use, the ability to perform multiple injections without repositioning the targeting device, and delivered a physical end product which is disposable to facilitate ease of implementation in further research.

47 Non-metal electrodes for local field potential recordings in magnetic resonance scanners
Jennifer Michelle Taylor1,2, Shan Hu3, Rajesh Rajamani4, Xiao-Hong Zhu2, Yi Zhang2, and Wei Chen1,2
1Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States, 2Radiology, University of Minnesota, Minneapolis, MN, United States,3Mechanical Engineering, Iowa State University, Ames, IA, United States, 4Mechanical Engineering, University of Minnesota, Minneapolis, MN, United States

The use of simultaneous neuronal recording and MRI is limited by artifacts induced both in the imaging and in the neuronal traces, but would provide a huge benefit to the exploration of brain mechanisms and understanding of the neurophysiology basis of fMRI. Here we have developed new electrodes using conductive, non-metal materials that produce no susceptibility artifacts in anatomical or functional imaging. Additionally, we show that the gradient induced artifacts in the neuronal trace are removable, revealing clean neuronal activity. These breakthroughs will allow for future experiments and studies exploring the neurovascular relationship between fMRI and neuronal activity.

3115.   48 Design of FPGA on-chip module for real-time image processing - permission withheld
Limin Li1 and Alice M. Wyrwicz1,2
1Center for Basic MR Research, NorthShore University HealthSystem, Evanston, IL, United States, 2Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States

This abstract presents the work on the design and testing of a real-time image processing module on a single-chip FPGA.

Monday 1 June 2015
Exhibition Hall 14:15 - 15:15

  Computer #  
3116.   49 Dipole Arrays for MR Head Imaging: 7T vs. 10.5T
Jinfeng Tian1, Russell Lagore2, and J. Thomas Vaughan2
1Center for Magnetic Resonance Research, U. of Minnesota, Minneapolis, Minnesota, United States, 2U. of Minnesota, Minnesota, United States

Dipole Array was proved to be a feasible RF coil for 7T body MRI, and has the potential to meet the RF challenges at 450MHz. With Finite Difference Time Domain method, a 8-ch head dipole array was studied at 300MHz and 450MHz to explore its feasibility for head MRI at 450MHz. Results show while the |B1+| magnitude on the central transverse slice gets worse from 300MHz to 450MHz, the |B1+| uniformity does not deteriorate with frequency. Dipole is a promising RF coil candidate for 10.5T Head MRI and thus deserves further study.

3117.   50 Asymmetrically segmented loop phased coil for uniform RF field excitation at 7T
Seunghoon Ha1, Haoqin Zhu1, and Labros Petropoulos1
1R&D, IMRIS Inc., Minnetonka, MN, United States

An asymmetric distributed capacitor capacitance loop array structure that generated highly homogenous B1 field for 7T MRI was presented. The calculated B1 field uniformity and coil sensitivity of the proposed coil was superior to the identical size loop array with symmetrically distributed capacitance as well as the stripline array coil with the same length. The volume shaped array loop coil assembly, consisting of the proposed asymmetric distributed capacitance coil design loops, was confirmed both through testing as well as confirmed our approach through B1+ field simulation study. Also, the proposed design will potentially help the construction of larger size loop arrays to cover more imaging volume at very high fields and obtain uniform coverage and high sensitivity.

3118.   51 Magnetic wall decoupling for dipole transceiver array for MR imaging: a feasibility test
Xinqiang Yan1,2, Xiaoliang Zhang3, Long Wei2, and Rong Xue1
1State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, Beijing, China, 2Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, Beijing, China,3Department of Radiology and Biomedical Imaging, University of California San Francisco and UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California, United States

Dipole antenna arrays have been applied for ultrahigh field MRI to obtain better SNR gain at the deep area of human tissues. However, there is no suitable decoupling methods proposed for dipole coil arrays in MRI. In this study, we investigated the possibility and performance of magnetic wall (MW) decoupling technique in dipole array designs. A two-channel MW decoupled dipole array was designed, constructed and analyzed experimentally. Both the bench test and experimental results indicate that the MW decoupling is a promising solution to reducing the electromagnetic coupling of dipole arrays, consequently improving their performance in SNR and parallel imaging.

3119.   52 Evaluation of a modified passive clamp decoupling network at high frequencies
Chathura Kumaragamage1,2 and Jamie Near2,3
1Biomedical Engineering, McGill University, Montreal, Quebec, Canada, 2The Douglas Brain Imaging Centre, Montreal, Quebec, Canada, 3McGill University, Montreal, Quebec, Canada

The efficacy of receiver coils decoupling, using clamping diodes on the Tx-line is investigated. We found that signal transmission (S21) is degraded due to impedance mismatching at high frequencies, when simple cross diode shunting is used along the Tx-Line (~8% power loss at 600MHz). A cross diode topology with an added tank circuit was found to improve S21 (~2% power loss at 600MHz). The modified cross diode topology provides an efficient solution for passive decoupling at high-frequencies that is remote to the coil, thus providing a convenient and safe alternative to passive decoupling networks mounted on the receiver coil element.

3120.   53 Matching-network noise dominating regime for receive coil loops
Xueming Cao1, Elmar Fischer1, Boris Keil2, Lawrence L Wald2,3, Jan G Korvink4, Jürgen Hennig1, and Maxim Zaitsev1
1University Medical Center Freiburg, Freiburg, Germany, 2A. A. Martinos Center for Biomedical Imaging, Dpt. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 3Harvard Medical School, Boston, MA, United States, 4IMTEK, University of Freiburg, Freiburg, Germany

As coil arrays have increasing number of channels, coil element continues to shrink. Therefore the noise originating from coil matching-networks should be considered explicitly. Here,we calculate the matching-network noise and define the concept of a matching-network noise dominating regime, which is a similar concept to the sample noise dominating regime. A criterion determining when the matching-network noise dominates is also formulated in the abstract.

3121.   54 31P MRSI of the brain at 3T with an improved 8-channel receive array and Whitened Singular Value Decomposition for optimal combination of 31P array signals
M.J. van Uden1, A. Rijpma2,3, C.T. Rodgers4, Bart Philips1, T.W.J. Scheenen1, and A. Heerschap1
1Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, Gelderland, Netherlands, 2Department of Geriatric Medicine, Radboud University Medical Center, Gelderland, Netherlands, 3Radboud Alzheimer Center, Radboud University Medical Center, Gelderland, Netherlands,4OCMR, RDM Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom

31P MRSI provides valuable information on metabolism in neurological diseases such as Alzheimer and brain tumors, but suffers from a relatively low SNR. We present an 8-channel receive array insert in a 31P/1H send birdcage coil for improved 31P MRSI of the brain. For the addition of the array coil signals we compared the Time-Domain and Whitened Singular Value Decomposition methods and observed a better SNR for the latter method. This method together with the improved head array insert resulted in about a 4–fold increase in the SNR of the 31P MR spectra compared to the birdcage coil.

3122.   55 Comparison of 16-channel Stripline and 10-channel Fractionated Dipole Transceive Arrays for Body Imaging at 7T
M. Arcan Erturk1, Alexander J. E. Raaijmakers2, Gregor Adriany1, Jinfeng Tian1, Pierre-Francois van de Moortele1, Cornelis A. T. van den Berg2, Dennis W. J. Klomp2, J. Thomas Vaughan1, Kamil Ugurbil1, and Gregory J Metzger1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, United States, 2Imaging Division, UMC Utrecht, Utrecht, Netherlands

MRI of the body/prostate at 7T is challenging due to electromagnetic-field effects. Using a multi-channel transmitter coil is necessary to focus the B1-fields at the target region to improve efficiency. There are several 7T multi-channel external surface-arrays, however a direct experimental comparison between these does not exist. Here, we compare the transmit/receive performance of 16-channel stripline (16SA) and 10-channel dipole-antenna (10DA) arrays on prostates of several subjects. Results show that, 16SA performs better in smaller subjects and targets closer to surface; and 10DA is more favorable in larger subjects, deeper targets and if a more uniform excitation profile is desired.

3123.   56 A 24-channel quadrature surface coil array for high-resolution human temporal lobe fMRI at 3T
Pu-Yeh Wu1, Ying-Hua Chu1, Shang-Yueh Tsai2, Wen-Jui Kuo3, and Fa-Hsuan Lin1
1Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan, 2Institute of Applied Physics, National Chengchi University, Taipei, Taiwan,3Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan

We developed a 24-channel coil array for human brain temporal lobe imaging. Specifically, we used 12 pairs of quadrature surface coil to optimize the SNR around the auditory cortex. Compared to two overlapped circular loops, quadrature coil pair can improve the SNR by 22%. Anatomical images acquired from our array show detailed brain structure of the temporal lobe. Compared to a 32-channel head coil array, our array shows SNR advantage at region no deeper than 5 cm from the scalp. Functional MRI measurements using our array show strong hemodynamic responses at the auditory cortex elicited by music.

3124.   57 Three-channel flexible phased array using circular coils with annex structure for decoupling
Jhy-Neng Tasso Yeh1 and Fa-Hsuan Lin1
1Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan

For the multi-channels phased-array coils, overlapping is commonly-used as a decoupling technique for loop-type RF coils, but it not only imposes a new spatial criterion but also limit the flexibility degree on flexible application. Here we propose the idea of annex-overlapping instead of traditional loop-overlapping, apply the concept of Koch first-order fractal-shape to deform the simple circular loop with additional outstretching annexes. The MRI image results of our prototypes of three-elements PA coils on a flexible plastic sheet all demonstrated the ability of simultaneous decoupling and flexibility against deformation, provided the potential for mechanically adjustable applications.

3125.   58 Triangular receiver coils to support superior/inferior acceleration
Paul T. Weavers1, Jacob N. Gloe1, Eric G. Stinson1, Phillip J. Rossman1, Thomas C. Hulshizer1, and Stephen J. Riederer1
1Radiology, Mayo Clinic, Rochester, Minnesota, United States

Dynamic contrast enhanced MRI (DCE-MRI) of the prostate has been shown to be a useful tool to detect and stage prostate cancer. Increasing parallel imaging acceleration will allow for better pharmacokinetic parameter estimation. Due to various acquisition constraints, the phase encode plane is typically misaligned with best supported plane for parallel imaging. Specialized receiver coils to support parallel imaging in this sub-optimal alignment have been developed and demonstrated.

3126.   59 Direct Derivation of Multi-Channel Receive Coil Sensitivity - permission withheld
Victor Taracila1 and Fraser Robb1
1General Electric, Aurora, Ohio, United States

Most of the literature on signal reception in magnetic resonance treats the reception mechanism utilizing the reciprocity theorem, according to which the receive sensitivity of the channels can be assessed through the transmit sensitivity of the same very array. In modern MRI receive phased array there are additional circuits attaches to the antennas, so that intuitively is difficult to follow the receive path through the reciprocity theory standpoint. We propose a direct method of deriving the receive sensitivity which we find more intuitive for MRI coil signal characterization, directly applicable when describing additional circuitry attached to the multichannel phased array.

3127.   60 High acceleration ability of a homemade 8-ch mouse phased array suggests the possibility for EPI-based functional studies of mice models using a standard 3T human scanner
Hui Han1, John Stager1, Wei Cao2, Miguel Navarro3, Fraser Robb3, Junghun Cho1, Nozomi Nishimura4, Chris Schaffer4, Valerie Reyna1, Yi Wang1, and Wen-Ming Luh1
1Cornell MRI Facility, Cornell University, Ithaca, New York, United States, 2Tongji Hospital, Huazhong University of Science and Technology, Hubei, China,3GE Healthcare, Ohio, United States, 4Biomedical Engineering, Cornell University, Ithaca, New York, United States

Here we show a homemade 8-ch mouse phased array interfaced to a standard 3T human scanner. A fact one may easily neglect is that the small imaging space allows for an excellent parallel imaging ability even for a low coil-element count (8) being used, which is a different scenario for a human coil with a larger imaging space. An initial trial, using single-shot gradient echo EPI with parameters tailored to fMRI, shows the possibility for functional studies of mice models. To our best knowledge, this is one of few first demonstrations to attempt fMRI of mice on a clinical system.

3128.   61 Lung-cardiac specific 1H RF array coil at 1.5 T
Madhwesha Rao1, Fraser Robb1,2, and Jim Wild1
1University of Sheffield, Sheffield, South Yorkshire, United Kingdom, 2GE Healthcare, Aurora, Ohio, United States

1H MRI is emerging as a viable modality for lung parenchyma imaging. However, 1H lung-MR methods have inherently low signal-to-noise ratio (SNR) in the parenchyma due to the lower 1H density (<0.2g/cc) and short T2*. Thus there are obvious gains to be made through anatomically customized radio-frequency (RF) receiver coil designs. In this work we propose a receiver RF coil array topology designed for high SNR imaging of the lung-cardiac anatomy at 1.5T and illustrate the 1H SNR improvement over a conventional 8 channel ladder-like topology used routinely for cardio-thoracic MRI.

3129.   62 Swaddle Coils for a Newborn
A.M. Flynn1, J.R. Corea1, P.B. Lechene1, P.D. Calderon2, T. Zhang3, G.C. Scott3, S.S. Vasanawala4, A.C. Arias1, and M. Lustig1
1EECS, Univ. of California, Berkeley, CA, United States, 2Diamant Engineering, Castro Valley, CA, United States, 3EECS, Stanford Univ., Palo Alto, CA, United States, 4Radiology, Stanford LPCH, Palo Alto, CA, United States

We have developed a system of flexible coils which can be wrapped closely around a newborn. Because newborns are often inserted into coils which do not fit well, SNR is typically worse than it could be. We have printed flexible coils and packaged them in pairs which can be attached arbitrarily to a swaddled infant. Swaddling naturally provides comfort to a baby. A snug fit will help restrict motion, recoup SNR and enable acceleration, hopefully one day alleviating the need to sedate small children who cannot stay still through an MRI exam.

3130.   63 Array coil and sample preparation and support system for whole brain ex vivo imaging at 100 μm
Azma Mareyam1, Jonathan R Polimeni1,2, Allison Stevens1, Andre Van Der Kouwe1,2, Loren D Bridgers3, Jason P Stockmann1,2, Matthew D Tisdall1,2, Lee Tirrell1, Allison L Moreau1, Ani Varjabedian1, Brian L Edlow1,2, Bruce Fischl1,4, and Lawrence L Wald1,2
1A.A. Martinos Center of Biomedical Engineering, Department of Radiology, Charlestown, MA, United States, 2Harvard Medical School, Boston, MA, United States, 3Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, 4CSAIL, Massachusetts Institute of Technology, Cambridge, MA, United States

We present an integrated system for 7T ex vivo imaging that meets several of the challenging design requirements needed to image a whole ex vivo brain at 100um isotropic resolution in 25 hours of averaging time. It incorporates a 31 channel receive array, an improved mechanical design, preamps mounted at the coil detectors, and an extended transmit coil design capable of producing high-power pulses. This new design substantially increases the range of ex vivo imaging applications.

3131.   64 Short dipole array for enhanced B1 efficiency/sensitivity at the expense of SAR
Alexander J.E. Raaijmakers1, Arcan Erturk2, Greg Metzger2, Cornelis A.T. van den Berg1, and Gregor Adriany2
1Imaging Division, UMC Utrecht, Utrecht, Utrecht, Netherlands, 2Center for Magnetic Resonance Research, Minneapolis, Minnesota, United States

We explored a dipole antenna design optimized for high B1 sensitivity/efficiency in the prostate while accepting increased SAR levels. Ten 20 cm dipole antennas have been constructed with T-shaped antenna legs. SAR levels were assessed by numerical simulations. This array was compared to an array of fractionated dipole antennas by SNR and B1+ measurements in the prostate and T2w TSE images. As expected, both B1 and SAR levels are higher for the short dipoles. The B1+/√SARmax ratio is 11.3% smaller and the SNR is 10% larger for the short dipole array. Image quality of the short dipoles is generally good.

3132.   65 Transmit Power Reduction and B1+ Homogenization Using 4-channel Regional RF Shimming for Shoulder Imaging at 3T
Yukio Kaneko1, Yoshihisa Soutome1,2, Kosuke Ito2, Masahiro Takizawa2, Hideta Habara1,2, Yusuke Seki1, Tetsuhiko Takahashi2, Yoshitaka Bito2, and Hisaaki Ochi1
1Central Research Laboratory, Hitachi Ltd., Kokubunji-shi, Tokyo, Japan, 2Hitachi Medical Corporation, Kashiwa, Chiba, Japan

The B1 inhomogeneity in a human body increases as the strength of a static magnetic field increases. Previous studies showed the effect of the number of RF transmit channels in RF shimming. However, the effect for a partial region of the shoulder in 3T has not yet been investigated. In this study, numerical simulation was used to investigate the effect of the number of RF transmit channels for regional RF shimming in the shoulder region in 3T. The results show that 4-channel RF shimming can contribute to improve the B1 homogeneity and reduce the transmit RF power more than 2-channel RF shimming.

3133.   66 A combined electric dipole and loop head coil for 7T head imaging
Gang Chen1,2, Karthik Lakshmanan1, Daniel Sodickson1, and Graham Wiggins1
1Center for Advanced Imaging Innovation and Research (CAI2R) and Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, 2The Sackler Institute of Graduate Biomedical Science, New York University School of Medicine, New York, NY, United States

At 7T the combination of loops and electric dipole antennas can provide higher central SNR in a body sized object than is possible with loop coils alone. An array of dipoles has been demonstrated for head imaging, and was shown to provide extended coverage in z compared to a standard birdcage, but suffered from low central SNR compared to loop-based coils. We investigate the addition of a loop array to the previously constructed dipole array. The dipole array is used for transmit and receive to explore the benefits of combining loops and dipoles for increased SNR in 7T head imaging.

3134.   67 A receive chain add-on for implementation of a 32-channel integrated Tx/Rx body coil and use of local receive arrays at 7 Tesla
Stephan Orzada1, Andreas K. Bitz2, Klaus Solbach3, and Mark E. Ladd1,2
1Erwin L. Hahn Institute for MRI, Essen, NRW, Germany, 2Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 3RF Technology, University Duisburg-Essen, Duisburg, Germany

Local Tx/Rx arrays for body imaging at ultra-high field are often bulky and consume much of the limited space inside the bore of the magnet. One option to allow patients with larger body physique and to enable a more clinic-like workflow is to implement an integrated Tx/Rx body coil situated between the gradient coil and the inner lining of the scanner bore. In this work, a receive chain add-on that allows implementation of an integrated 32-channel Tx/Rx body coil to be used together with local receive arrays was successfully developed. The add-on is configured such that normal operation of the system including measurement of X-nuclei is feasible.

3135.   68 Initial Results: Ultra-High Field 32-ch Tx Body Array with Bright Centers.
Shailesh B. Raval1, Tiejun Zhao2, Narayanan Krishnamurthy1, Yujuan Zhao1, Sossena Wood1, Kyongtae Bae1, and Tamer S. Ibrahim1
1University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2Siemens Medical Solutions, Pittsburgh, Pennsylvania, United States

Body imaging exams are increasingly growing as a part of total clinical MRI exams at lower field (<=3T) and should translate towards UHF imaging because of its excellent promises. Thus, there is a critical need to investigate advancing MR body imaging (kidney, liver and pancreatic) at 7T. The goal of this study is to introduce a new 32-ch Tx array design that; similar to head coils, is capable of producing bright centers inside the torso at 7T using its CP mode.

3136.   69 Boosting 31P signals by using a 7 channel Receive Array at 7T
Bart L. van de Bank1, Frits Smits1, Miriam W. van de Stadt-Lagemaat1, and Tom W.J. Scheenen1,2
1Departement of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, Netherlands, 2Erwin L. Hahn Institute, University Duisburg-Essen, Germany

Separating transmission and reception of signals can significantly boost SNR of 31P signals, therefore we developed a 7-channel 31P receive-only array that could be used with a detunable 31P birdcage, which was inserted into an 8-channel 1H head-coil. Signals could be enhanced further by exploiting the Nuclear Overhauser Effect as was shown in-vivo.

3137.   70 3D-Printed Microstrip Resonators for 4.7T MRI
Saeed Javidmehr1, Adam Maunder2, Mojgan Daneshmand1, and Nicola De Zanche3
1Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada, 2Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada, 3Oncology, University of Alberta, Edmonton, Alberta, Canada

The emerging technology of 3D printing is expanding into the electronics industry and is replacing traditional fabrication methods for a variety of products with significantly lower costs and labour. In this study, microstrip resonator coils are 3D-printed with built-in matching and tuning capacitors using various dielectric and conductive materials. Our 3D printed partially air-filled MTL resonators show comparable performance to standard hand-made foam-core resonators using copper conductors and discrete capacitors.

3138.   71 Harmonic excitation of MR signal for interventional MRI
Dmitri Artemov1 and Yoshinori Kato1,2
1Radiology, Johns Hopkins University, Baltimore, MD, United States, 23 Life Science Tokyo Advanced Research Center, Hoshi University, Tokyo, Shinagawa-ku, Japan

MR-detectable devices are important for interventional procedures, and should provide a clear imaging signature while not degrading diagnostic imaging quality. A new MR-detectable probe design is presented, based on excitation of MR signals by high-frequency RF harmonics generated by the probe with a non-linear element. The implantable probe was designed to excite MR signals when driven by an external RF filed at half-resonance frequency. A second harmonic at the resonance frequency was generated by a non-linear diode element. MR signals in the subject were excited only in close proximity to the probe and could be detected by a standard receiver coil.

3139.   72 Onboard RF Combination for Receiver Channel Reduction - permission withheld
Ziyuan Fu1, Mark Bolding2, and Shumin Wang1
1Auburn University, Auburn, AL, United States, 2Radiology, University of Alabama, Birmingham, AL, United States

Multi-channel surface receiver arrays are a popular approach for improving the signal-to-noise ratio (SNR) in MRI when sample noise is dominant1. It has been demonstrated that even at the center of the human head where conventional circularly polarized birdcage coils perform very well, the SNR can still be significantly increased by using a receiver array2. In order to support their functionality, multi-channel receiver systems are normally required on a MRI scanner. The aim of this study is to develop an onboard RF combination circuit that can support multi-channel signal reception with fewer or just one RF receiver channel.

Monday 1 June 2015
Exhibition Hall 15:15 - 16:15

  Computer #  
3164.   1 Analysis of FDTD Field Simulation and Experimental Results in a Monopole Antenna Array Coil at 7T
Myung-Kyun Woo1, Suk-Min Hong2, Jongho Lee1, Young-Bo Kim3, and Zang-Hee Cho4
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, 2Institute of Neuroscience and Medicine - 4, Forschungszentrum Jüilich, Jülich, Germany, 3Gil Hospital, Incheon, Korea, 4Neuroscience Research Institute, Incheon, Korea

Many RF coils have been developed to solve field non-umiformity at ultra-high field. Recently, radiative antenna type with poynting vector has been proposed at UHF. This abstract is to evaluate newly developed radiative antenna type coil, Extended Monopole antenna Array with individual Shields (EMAS) coil at 7T. To analyze, we calculated simulated B1+ field and specific absorption rate (SAR) with Monopole antenna Array (MA), Extended Monopole antenna Array (EMA), and EMAS coils. Then the simulated results were compared with the experimental results. The EMAS coil successfully extended the spatial coverage with uniform B1+ field distribution.

3165.   2 Optimal Arrangement of Finite Element Loop Arrays for Parallel Imaging in a Spherical Geometry at 9.4 T
Andreas Pfrommer1 and Anke Henning1,2
1Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 2Institute for Biomedical Engineering, UZH and ETH Zurich, Zurich, Switzerland

Parallel imaging with a finite number of array elements is limited by the g-factor enhancement for high k-space undersampling. To fully exploit the unfolding potential of circular surface coils surrounding a spherical head phantom, we developed an optimization routine to minimize the maximum value of the g-factor inside the “head” region. As a result we showed optimal arrangements for 8, 16 and 32 channels at 9.4 T with different acceleration rates. Moreover we precisely specified the range of possible gmax values for each setup including optimal and worst case positioning of the loops.

3166.   3 Potential gain of a 256 channel head coil at 7T: combined measurements and g-factor calculations
Arjan D. Hendriks1, Michel G.M. Italiaander2, Natalia Petridou1, and Dennis W.J. Klomp1,2
1Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands, 2MR Coils B.V., Drunen, Netherlands

Recent developments in high-density surface receiver arrays, together with high BOLD sensitivity at 7T, allow human fMRI at ~0.5mm isotropic resolution and a volume acquisition time in the order of few seconds. However, with element sizes of 1x2cm and 32-channels, these benefits are limited to a small field of view. In this study, the expected g-factor gain of a 256-channel surface coil is estimated by combining 8 measurements of a high-density 32 channel surface coil. Results show that benefits achieved with 32-channels can extend to 256-channels. Full head coverage and decreased g-factors (gain in SNR or acceleration) can be achieved.

3167.   4 A novel design 20-channel head coil for cortical imaging with ultra-high resolution.
Alexander Beckett1,2, Liyong Chen1,2, An T Vu3, and David A Feinberg1,2
1Helens Wills Neuroscience Institute, University of California, Berkeley, CA, United States, 2Advanced MRI Technology, Sebastopol, CA, United States,3CMRR, University of Minnesota, Minneapolis, MN, United States

Advances in imaging hardware and pulse sequences have led increasingly finer resolution imaging at ultra-high fields. We propose to use a novel half shell 20 channel coil designed for optimized imaging in neocortical regions superficial and closest to the coil array rather than deeper brain regions, and demonstrate the advantages of such a coil over a standard 32-channel array in terms of raw signal and tSNR at 0.75 mm and 0.55 mm isotropic resolution. We demonstrate fMRI imaging at 0.75 mm. New coil designs will allow even higher resolutions in future cortical imaging studies with maximal SNR.

3168.   5 High-Throughput Diffusion-Tensor-Imaging of Mouse Brains using a four-coil system
John C Nouls1, Alexandra Badea1, Gary P Cofer1, and G Allan Johnson1
1Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, United States

Diffusion-tensor imaging of mouse brains, used in conjunction with population atlases and statistical methods, can detect subtle pathologies. The total scan time can be prohibitive. We present a parallel acquisition, four-coil system increasing diffusion-tensor imaging throughput in a small bore, 7T scanner. The geometry of the coil system and its shielding has been optimized to preserve SNR, enabling a decrease in imaging time per specimen of 63%. The fractional anisotropy measurement bias due to off-center imaging was 9%. Bringing each coil slightly closer to the magnet isocenter may further decrease imaging time towards the maximum 75% reduction achievable.

3169.   6 Performance evaluation of 2-channel endorectal coil geometries for imaging the prostate at 7T
M. Arcan Erturk1, Gregor Adriany1, and Gregory J Metzger1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, United States

In prostate MRI at 7T, use of endorectal coils (ERCs) can improve the signal-to-noise ratio (SNR) more than 4-fold compared to using an external surface array (ESA). Here, we compare the SNR and transmit performance (B1+) of three different 2-channel ERC coil geometries (two loops, ERC-2OL; stripline-large loop, ERC-SLL; stripline-small loop, ERC-SSL) inside a uniform torso-sized phantom. ERC-SSL performed the best among the ERCs. SNR and B1+ of ERC-SSL compared to a 16-channel ESA has improved ~5.6-fold and ~6.9-fold, respectively. Reusable, rigid, multi-channel ERCs are a valuable tool in imaging the prostate at 7T.

3170.   7 A novel decoupling technique for multiple-row microstrip transceiver array designs
Xinqiang Yan1,2, Long Wei2, Rong Xue1, and Xiaoliang Zhang3
1State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, Beijing, China, 2Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, Beijing, China,3Department of Radiology and Biomedical Imaging, University of California San Francisco and UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California, United States

Compared with regular single-row transceiver coil arrays, multiple-row arrays exhibit larger imaging coverage and the capability of parallel imaging and parallel excitation along z-direction. The main challenge in designing multiple-row microstrip array is to attain sufficiently decoupling among coil elements from adjacent rows. In this study, a novel decoupling technique was proposed to address this problem. Both the bench test and MR imaging results demonstrate that the proposed technique could reduce the strong coupling (-7.9 dB) between microstrip elements from adjacent rows to a sufficiently small value (-25.3 dB).

3171.   8 Tx-array design strategies for reducing excitation artifact and local SAR hot spots in pTx MRI
Pei-Shan Wei1,2, Mike J. Smith2, Christopher P. Bidinosti3, and Scott B. King1,2
1Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada, 2National Research Council of Canada, Winnipeg, Manitoba, Canada, 3Department of Physics, University of Winnipeg, Winnipeg, Manitoba, Canada

Local SAR minimization is of particular importance for Tx-array MRI. We hypothesize that high local hot spots in excitation artifacts are partially due to strong asymmetries in B1+ fields of individual array elements of a Tx-array, which are more prominent at higher B0 fields. We show that modifications to the individual array element geometries, that improve both B1+ symmetry and reduce local B1+ hot spots, resulted in reduced hot spots in excitation artifact, in our case by 25%. Such Tx-array design strategies can improve performance of pTx MRI and may lower local SAR hot spots relative to traditional Tx-array designs.

3172.   9 A 3 channel 31P and 2 channel 1H coil array for 31P NMR in the visual cortex at 7 T
Sigrun Goluch1,2, Andre Kuehne1,2, Albrecht Ingo Schmid1,2, Ewald Moser1,2, and Elmar Laistler1,2
1MR Center of Excellence, Medical University of Vienna, Vienna, Austria, 2Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria

This abstract presents the development of a 3 channel 31P and 2 channel 1H RF coil array for phosphorous spectroscopy in the human visual cortex at 7 T. The naturally low sensitivity of 31P spectroscopy requires very efficient RF hardware for a successful implementation of an experiment. The array was modeled and optimized with the help of 3D electromagnetic simulation and was build and tested on the bench with a network analyzer. Preliminary results were obtained inside the scanner (Siemens, ) with phantom and fruit measurements, showing good results.

3173.   10 Two-channel High-Temperature Superconducting Array for Diffusion Tensor Imaging of Rat Spinal Cord at 7T
Yun-Jie Li1, Meng-Chi Hsieh1, In-Tsang Lin2, Xiao-Liang Zhang3, and Jyh-Horng Chen1,4
1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan, Taiwan, 2Xiamen University, Xiamen, Fujian, China, 3Department of Radiology and Biomedical imaging, University of California, University of California, California, United States, 4Dept. of Electrical engineering, National Taiwan University, Taipei, Taiwan, Taiwan

This is the development of high-temperature superconducting array coil,and we apply it on the rat spinal cord DTI

3174.   11 Preliminary investigation on shielding-ring based decoupling technique for small monolithic RF coils
Zhoujian Li1, Roberta Kriegl2,3, Elmar Laistler2,3, Marie Poirier-Quinot1, Luc Darrasse1, and Jean-Christophe Ginefri1
1Laboratoire d’Imagerie par Résonance Magnétique Médicale et Multi-Modalités (IR4M), UMR8081 CNRS, Université Paris-Sud, Orsay, France, 2Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria, 3MR Centre of Excellence, Medical University of Vienna, Vienna, Austria

A shielding ring based decoupling technique was investigated for small monolithic HTS coils, an analytical model based on magnetic flux compensation to determine the geometric configuration of two neighbor shielding rings to achieve optimal decoupling was developed and validated experimentally using a two-MTLR copper array, and the effect of the shielding rings on the overall coil losses was evaluated using a standard 2-coil array cooled at LN2 temperature. Results show that configuration achieving near-optimal decoupling can be obtained using this model, and high Q-factor value by employing HTS material can be expected by exploiting this technique.

3175.   12 Comparison of improved breast magnetic resonance guided focused ultrasound system with improved radio frequency phased array coils.
Emilee Minalga1, Robb Merrill1, Dennis L Parker1, Allison Payne1, and J. Rock Hadley1
1UCAIR, University of Utah, Salt Lake City, UT, United States

This abstract describes an improvement on a previously designed system for breast magnetic resonance guide focused ultrasound treatments. Results include a signal to noise comparison. The improved design give better signal to noise ratio throughout the treatment volume.

3176.   13 Optimization of an 8-channel receive-only surface array for whole brain MRI of marmosets
Daniel Papoti1, Cecil Chern-Chyi Yen1, Pascal Sati1, Joseph Robert Guy1, Daniel S Reich1, and Afonso C. Silva1
1NINDS, National Institutes of Health, Bethesda, Maryland, United States

In this work we describe the development and comparison of three different 8-channel receive-only arrays built to provide whole brain MRI coverage of marmosets with high sensitivity. Among all coils built, the design based on a central elliptical element partially overlapped with 7 loops showed excellent coverage with high sensitivity throughout the whole brain. A gain up to 60% in SNR in the frontal cortex, 40% in the occipital cortex, and 20% in the center of the brain was achieved when compared to the other two geometries. High-resolution brain images obtained from an autoimmune encephalomyelitis animal clearly show white matter lesions in both T1- and T2-weighted images.

3177.   14 Asymmetric Transceiver Phased Array for Functional Imaging and Spectroscopy of the Visual Cortex at 9.4 T
Nikolai I Avdievich1, Ioannis A Giapitzakis1, and Anke Henning1,2
1Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 2Institute for Biomedical Engineering, UZH and ETH Zurich, Zurich, Switzerland

Ultra-high field (>7T) RF coil design is challenging due to decreased transmit efficiency and strongly distorted B1 field profile. For functional SI of the visual cortex open RF coils are highly suitable since they provide an easy access and increased transmit efficiency by focusing RF field. In this work we demonstrated that a 9.4T 5-channel array with asymmetric arrangement of 4 transmit and 4 receive elements improves the transmit profile without compromising the reception. We also evaluated changes in the transmit efficiency, penetration depth and SAR due to variation in the array size and the phase shift between the elements.

3178.   15 An SNR Comparison Between a Sodium Phased Array Coil and a Single Channel Coil
Amin Nazaran1, Joshua D Kaggie2,3, Meredith Taylor1, Daniel J Park1, Grayson Tarbox1, Rexford D Newbould4, Neal Bangerter1, and Glen Morrell3
1Electrical and Computer Engineering, Brigham Young University, Provo, Utah, United States, 2Physics, University of Utah, Salt Lake City, Utah, United States, 3Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, United States, 4Imanova Centre for Imaging Sciences, London, United Kingdom

In this abstract, we compared a new phased array sodium breast coil with a single channel sodium coil. The new phased array coil consists of 7 sodium loops that are overlapped to minimize coupling to adjacent sodium loops. The coil used for comparison has a single transmit/receive 1 H loop and a single transmit/receive 23Na loop. The benefits of our new coil include larger volume coverage, and higher SNR (2-3x) than the single channel coil near the surface loops.

3179.   16 Streamlined construction of a six-channel mouse array coil with 3D printing
Wen-Yang Chiang1 and Mary P McDougall1
1Department of Biomedical Engineering, Texas A&M University, College Station, TX, United States

Mechanical stability is crucial in geometric decoupling, especially for small-form-factor wire array coils because the dimensional tolerance is less forgiving. To this end, we incorporated 3D printing to streamline the development of our mouse array coil when solid wire was used. When the solid wire and the PCB were embedded inside of the 3D printed former, we were also able to not only place the array coil as close to the specimen as possible, but also able to maintain the geometric decoupling overtime. Because no glue was used, we could replace any coil components easily. SNR of phantom images acquired by the proposed mouse array coil and by a commercial Varian quadrature mouse birdcage coil were compared. We also quantitatively compared the consistency of the coil sensitivity of each array coil element.

3180.   17 A Novel Compact 10-Channel Phased Array for a Dedicated 1.5T Neonate MRI System
Wolfgang Loew1, Yu Li1, Ron Pratt1, Jean Tkach1, Charles Dumoulin1, and Randy O Giaquinto1
1Imaging Research Center, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States

A compact 10-channel receive array for neonatal abdomen and chest MRI was developed to enable parallel imaging on a small-footprint 1.5 Tesla superconducting NICU MR-system. The development of the receive array also necessitated the creation of a transmit-only birdcage coil. Coil performance of the phased array was evaluated electrically and on phantoms with clinical imaging protocols.

3181.   18 Active Decoupling of RF Coils: Application to 3D MRI with Concurrent Excitation and Acquisition
Ali Caglar Ozen1,2, Michael Bock1, and Ergin Atalar2
1Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany, 2Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey

3D MRI with concurrent excitation and acquisition (CEA) is implemented with active decoupling of radio frequency coils. The transmit coil is geometrically decoupled from the receive coil, and the remaining B1-induced voltages in the receive coil during CEA are minimized by the second transmit coil using a careful adjustment of the phase and amplitude settings in this coil. CEA MR images could be reconstructed from an ex vivo animal.

3182.   19 A 7T transmit and receive array combination for simultaneous investigation of electrophysiology and fMRI in non-human primates
Shajan G1, David Zsolt Balla1, Thomas Steudel1, Philipp Ehses2, Hellmut Merkle1, Nikos Logothetis1,3, Rolf Pohmann1, and Klaus Scheffler1,2
1Max Planck Institute for Biological Cybernetics, Tuebingen, Baden Wuerttemberg, Germany, 2Department of Biomedical Magnetic Resonance, University Hospital, Tuebingen, Baden Wuerttemberg, Germany, 3University of Manchester, Manchester, United Kingdom

Simultaneous investigation of electrophysiology and fMRI in non-human primates presents several challenges on RF coil design. Transmit coil structure should allow access for electrodes from different orientations to allow recordings from different brain regions. Receive arrays must be designed around head posts fixed on the animal head, leading to non-optimum coil orientations in the helmet. In cases with more than one head posts, the receive array must be on two separable halves of the helmet. We developed an RF coil arrangement that optimizes the SNR and provides access for recordings from different regions of the brain.

3183.   20 Analytical Performance Evaluation and Optimization of Resonant Inductive Decoupling (RID)
Andre Kuehne1,2, Elmar Laistler1,2, Anke Henning3,4, Ewald Moser1,2, and Nikolai I Avdievich3
1Center for Medical Physica and Biomedical Engineering, Medical University of Vienna, Vienna, Austria, 2MR Centre of Excellence, Medical University of Vienna, Vienna, Austria, 3Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 4Institute for Biomedical Engineering, UZH and ETH Zurich, Zurich, Switzerland

We derive an analytical framework for analyzing the coil power efficiency impact of resonant inductive decoupling (RID) for arbitrary channel coils. It is applied to a two-channel array, and analytical expressions for load power deposition dependent on the resistive coupling factor, degree of coupling compensation and relative driving phase shift between elements are derived. The results show that coil performance can be enhanced or degraded by RID, depending on the exact coil application scenario, and great care needs to be taken in a practical setup.

3184.   21 A novel transceiver wired & wireless array coil assembly for MR guided robot assisted interventions and radiosurgery procedures
Seunghoon Ha1, Haoqin Zhu1, and Labros Petropoulos1
1R&D, IMRIS Inc., Minnetonka, MN, United States

A novel transceiver wireless array coil that can be utilized for robotic assisted MR guided interventions and radiosurgery procedures was presented. The coil assembly consists of a posterior unit comprising of eight channels transceiver array pattern and an anterior wireless transceiver loop array coil that is inductively coupled to the posterior part. The coil assembly generated a high uniform and sensitive B1+ profile over the entire hear without inhibiting valuable surgical space and compromising the sterile field. SAR calculations indicate that the presence of the anterior wireless transceiver loop array does not alter or enhance the SAR pattern behavior inside the human head.

3185.   22 Validation of A Semi-flexible 64-channel Receive-only Phased Array For Pediatric Body MRI at 3T
Tao Zhang1,2, Joseph Y Cheng1,2, Paul D Calderon1, Thomas Grafendorfer3, Greig Scott2, Bob Rainey3, Mark Giancola3, Fraser Robb3, John M Pauly2, Brian A Hargreaves1, and Shreyas S Vasanawala1
1Radiology, Stanford University, Stanford, CA, United States, 2Electrical Engineering, Stanford University, Stanford, CA, United States, 3GE Healthcare, WI, United States

Clinical pediatric MRI is often performed using receive coils designed for adult patients. The mismatch of the receive coils and the pediatric patients can cause degraded image quality. In this work, a 64-channel receive-only phased array dedicated for pediatric body MRI is designed and constructed. This coil array incorporates the quarter-wavelength-balun technique, achieves ideal coil decoupling, and is very flexible in one direction conforms to different pediatric patient sizes. Here, we validated the performance and flexibility of the coil array in phantom and in vivo studies.

3186.   23 A Dual-Tuned Two-Element Array for 1H/2H Imaging at 1 Tesla
Scott A. Blasczyk1, John C. Bosshard1, Neal A Hollingsworth1, Brian J Bass1, and Steven M Wright1
1Electrical and Computer Engineering, Texas A&M University, College Station, TX, United States

Imaging and spectroscopy of multiple nuclei with phased arrays has demonstrable utility in magnetic resonance. Our application involves imaging of deuterium and proton. Deuterium has been used for glucose monitoring, tracking bolus diffusion, and providing a signal lock. We have developed a dual-tuned, geometrically decoupled two-element receive array for sequential or interleaved imaging of proton (1H) and deuterium (2H) at 1T. Array elements are detuned passively during transmit with crossed diodes, while transmit elements are detuned during receive using PIN diodes. 1H and 2H Images of a deuterated water phantom taken at 1T are shown.

3187.   24 Signal combination Mode Matrix Calculation on Considering Multiregion SNR - video not available
Zhang Qiong1, Sun zhi guo1, Liu Wei1, and Wang jian min1
1Siemens, ShenZhen, GuangDong, China

The concept of ¡°Mode Matrix¡± has been proposed in reference. It¡¯s mainly geared towards parallel imaging techniques which require array elements stacked in phase encoding direction [2-4]. The pre-combining signals use Mode Matrix to scale the number of necessary RF channels as a function of the acceleration factor. In this work, we provide a new method for Mode Matrix calculation without considering the array distribution.