RF Design II
Engineering/Interventional/Safety Monday, 17 May 2021
Oral
175 - 184
Digital Poster

Oral Session - RF Design II
Engineering/Interventional/Safety
Monday, 17 May 2021 18:00 - 20:00
  • Coil Design Impacts Image Encoding: Optimized 64-Channel Array Configurations for Diffusion-Weighted Imaging in 3T Cardiac MRI
    Robin Etzel1,2, Choukri Mekkaoui3, Ekaterina S Ivshina4, Alina Scholz1, Markus W May1, Nicolas Kutscha1, Matthäus Poniatowski1, Chaimaa Chemlali1, Anpreet Ghotra1, Sam-Luca JD Hansen1, Timothy G Reese3, Lawrence L Wald3, Andreas H Mahnken2, and Boris Keil1
    1Institute of Medical Physics and Radiation Protection, Department of Life Science Engineering, TH Mittelhessen University of Applied Sciences, Giessen, Germany, 2Philipps-University of Marburg, Department of Diagnostic and Interventional Radiology, Marburg, Germany, 3Harvard Medical School, Massachusetts General Hospital, Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Boston, MA, United States, 4Princeton University, Princeton, NJ, United States
    Three 64-channel arrays were constructed and evaluated to determine the optimum configuration for highly accelerated in vivo cardiac diffusion-weighted imaging. The configuration with a non-uniformly distributed loop density demonstrated most favorable cardiac imaging performance.
    Figure 1: The three constructed array coils with covers open: (A) symmetrically distributed equally-sized loops in an overlapped arrangement, (B) a gapped array with symmetrically distributed equally-sized loops, and (C) a non-uniformly loop density variation.
    Figure 5: Coil comparison in a healthy volunteer. Color-coded maps of the SNR using each coil at mid-ventricle (A). Statistical comparison of the SNR for each coil at specific regions in the myocardium (B). Tractogram of the entire myocardium (left and right ventricle), color-coded by the myofiber helix angle (C).
  • A 128-Channel head coil array for Cortical Imaging at 7 Tesla
    Bernhard Gruber1,2, Jason P. Stockmann1, Azma Mareyam1, Boris Keil3, Anpreet Ghotra3, David A. Feinberg4, and Lawrence L. Wald1
    1Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, 2High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria, 3Department of Life Science Engineering, Institute of Medical Physics and Radiation Protection, Mittelhessen University of Applied Science, Giessen, Germany, 4Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
    We designed, built and simulated a 128-channel receive array for cortical brain imaging at 7T to maximize SNR and achieve highest accelerations needed for single-shot EPI based fMRI at sub-millimeter isotropic resolution.
    (A) 3D rendering of the novel 128-ch brain array with a 24-ch parallel Transmit Array setup. The pTx array is organized in 3 rows of 8. (B) 3D rendering of the whole 128-channel brain receive coil setup at 7 Tesla in SolidWorks (Dassault Systems, France). The table spoon extension (blue) with the Rx and Tx coils is connected to an interface box (brown) that slides into the MRI bore (C) Side and back view of the 128-ch coil array without populated elements. The transmit (Tx) coils (1-ch birdcage or 24-ch pTx) slide over the receive (Rx) array.
    (A) Simulated unaccelerated SNR maps of a 32-, 64-, and 128-channel array in a transverse, coronal and sagittal slice. For simulation in MARIE a uniform head model (average brain: epsilon=52, sigma=0.55 S/m), which closely matches the average brain tissue, was used. (B) Simulated accelerated SNR maps for R=5 and R=3x3 of the 32-, 64-, and 128-channel array. (C) SNR profiles through a central axial slice for the 128-channel (red line), 64-channel (green line), and 32-channel (blue line).
  • A 128-channel receive array for 10.5T human head imaging
    Russell Luke Lagore1, Steve Jungst1, Jerahmie Radder1, Edward J Auerbach1, Steen Moeller1, Andrea Grant1, Lance DelaBarre1, Matthew Waks1, Pierre-Francois Van de Moortele1, Gregor Adriany1, and Kamil Ugurbil1
    1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States
    A 128-CH RX array is designed & prototyped for human head imaging at 10.5T. The coil uses  flexible PCBs for loop conductors. Results for eight loops show low coupling and good stability. EM simulations will estimate the SNR gain over a 64-CH array which will be verified experimentally.
    Figure 1: Receive array former (helmet) shown from several angles: (B) Front, (C) Side, (D) Back, and (E) Top. Front end electronics (preamps and PIN diode bias tees) are shown mounted to the top plate. The top plate mounts to the helmet via a 3D printed central pillar and four 12 mm diameter fiberglass rods.
    Figure 4: Off-coil (top-left) and on-coil (bottom-left) preamp PCBs are shown in the photo along with corresponding circuit schematics (right) for the loop feed circuit and preamp board.
  • A Quintuple-Tuned RF Coil for Whole Brain Multi-Nuclei Magnetic Resonance Imaging and Spectroscopy at 7T
    Jiying Dai1,2, Tijl A. van der Velden1, Johannes M. Hoogduin1, Fabian Bartel2, Ettore F Meliadò1,2, Mark van Uden2, Catalina S. Arteaga de Castro2, Evita C. Wiegers1, Martijn Froeling1, Mark Gosselink1, Alexander J. E. Raaijmakers1,3, and Dennis W. J. Klomp1,4
    1Radiology, UMC Utrecht, Utrecht, Netherlands, 2Tesla Dynamic Coils, Zaltbommel, Netherlands, 3Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands, 4Tesla Engineering Ltd, West Sussex, United Kingdom
    With META Head coil, the acquisition time for 1H, 31P and 23Na in vivo scans is less than 25 minutes in total, with high SNR, providing ample time to potentially add 13C and/or 19F acquisitions in the same scan session following (labeled) infusions. 
    META Head Coil: a) The coil on the 7T MR system including the 31P bore coil (embedded in bore) and the 23Na clamp; b) The eight-channel dipole array as RF transceivers for 1H and 19F; c) The fifteen-channel receiver array for 31P, 23Na and 13C; d) The entire coil; e) The digital interface platform under the front cover of d.
    a) and b): Scan result from a brain 31P CSI FID, TR=71.1ms, FA=13deg, voxel size =20*20*20mm3, Hamming-weighted NSA=70, duration=10min: a) a slice from the 3D dataset showing the spectral map at full brain coverage, the background image is overlaid manually for illustration; b) 31P spectrum of the marked voxel of Figure a; c) and d): Signals from a close-fit head birdcage[2] and the META head coil, at the center of a phantom. The SNR comparison was assessed by scaling the data to obtain the same standard deviation in the spectral noise then taking the integral of the signal in spectral domain.
  • A Self-decoupled 64 Channel Receive Array for Human Brain MRI at 10.5T
    Nader Tavaf1, Steve Jungst1, Russell L. Lagore1, Jerahmie Radder1, Steen Moeller1, Andrea Grant1, Edward Auerbach1, Kamil Ugurbil1, Gregor Adriany1, and Pierre-Francois Van de Moortele1
    1Center for Magnetic Resonance Research (CMRR), University of Minnesota Twin Cities, Minneapolis, MN, United States
    A 1.95 fold increase in average signal-to-noise ratio at 10.5T using a 64-channel receiver compared to a 32-channel receiver was demonstrated experimentally in human head phantom imaging.
    Figure 3 – Experimental SNR comparison between the 64-channel 10.5T receive array (top row) and the 32-channel 10.5T receive array (bottom row) at 7 axial slices.
    Figure 1 – As-built photograph of the 64 channel 10.5T receive array for human brain imaging.
  • Development of Two Antisymmetric 16-Element Transceiver Coil Arrays for Parallel Transmit Cardiac MRI in Humans at 7T
    Ibrahim A. Elabyad1, Maxim Terekhov1, and Laura M. Schreiber1
    1Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
    Parallel imaging with acceleration factor R=6 was possible using Design2 while maintaining the mean g-factor of 1.47 within the pig heart. Ultra-high-resolution (0.35×0.35×4mm3) T2* weighted images were acquired on a fresh pig cadaver using R=5.
    Figure 2. Simulated central combined 2D $$${B_1^+}$$$-field distribution in central axial, sagittal, and coronal planes within Duke and Ella voxel models computed for the optimal phase vectors (PV1 and PV2 for Design1, and PV3 and PV4 for Design2). Both cardiac arrays were fed with and all coil elements were fed with equal amplitudes. Values of RSD and mean $$$Tx_{eff}$$$ ($$$\mu{T}\sqrt{kW}$$$) were computed in the selected 2D ROI and written on each image.
    Figure 5. (a) Ultra-high resolution T2* weighted images of the SA and LA heart views acquired with array Design2. (b) T2* weighted images of the LA view acquired with the spatial resolution 0.35×0.35×4mm3 at different GRAPPA acceleration factors to check parallel imaging capability of the array Design2.
  • A Patient-Friendly 16ch Tx / 64ch Rx Array for Combined Head and Neck Imaging at 7 Tesla
    Markus W. May1, Sam-Luca J.D. Hansen1, Nicolas Kutscha1, Gurinder Kaur Multani1, Mirsad Mahmutovic1, Matthäus Poniatowski1, Rene Gumbrecht2, Ralph Kimmlingen2, Markus Adriany2, Yulin Chang3, Bastien Guerin4, Christina Triantafyllou2, Lawrence L. Wald4, and Boris Keil1
    1Institute of Medical Physics and Radiation Protection (IMPS), TH Mittelhessen University of Applied Sciences, Giessen, Germany, 2Siemens Healthcare GmbH, Erlangen, Germany, 3Siemens Medical Solutions USA, Inc., Malvern, PA, United States, 4A.A. Martinos Center for Biomedical Imaging, Dept of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
    A 16chTx / 64chRx head-neck array coil was designed to increase patient comfort, constructed to extend the coil coverage, and validated at 7T ultra-high field MRI.
    (A,B) Anterior and posterior housings segment of the 16chTx /64chRx head-neck coil maintaining a constant offset of the transmit to the receiver loops. (C,D) populated coil array with cut-outs for eyes and mouth facilitate visual stimulation and free breathing, respectively. Each Tx loop consists of 7 -13 capacitors, a PIN diode circuitry for active tuning, and a symmetrical drive port. (D) Final enclosed coil plugged into the 7T scanner’s patient bed illustrating the goal of making a form factor matching what is clinically used at 1.5T and 3T.
    Sagittal 7T GRE in vivo image acquired with the constructed 16chTx /64chRx head-neck coil to demonstrate the extended coil coverage (TR/TE/α:40ms/5ms/20, matrix: 344x344, resolution: 0.3 x 0.3 x 5mm, BW: 320Px/Hz).
  • A 16-channel transmit 96-channel receive head coil for NexGen 7T scanner
    Shajan Gunamony1,2, Roland Müller3, Paul McElhinney1, Sydney Nicole Williams1, Nicolas Groß-Weege3,4, Nikolaus Weiskopf3,5, Harald E Möller3, and David Feinberg6
    1Imaging Centre of Excellence, University of Glasgow, Glasgow, United Kingdom, 2MR CoilTech Limited, Glasgow, United Kingdom, 3Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 4Siemens Healthcare GmbH, Erlangen, Germany, 5Faculty of Physics and Earth Sciences, Felix Bloch Institute for Solid State Physics, Leipzig, Germany, 6Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States
    Initial measurements demonstrate significant gains in SNR and parallel imaging performance. Further characterisation of the transmit and receive performance of this setup is planned.  
    Figure 2: A – Picture of the completed receive array. An input board on the helmet surface consists of the matching and active detuning circuit. A feed-board with preamplifier is on a holder above the helmet; B – Picture of the final setup; C – View from the service end highlighting the visual field.
    Figure 1: A – EM simulation setup. Tuning, matching and decoupling was adjusted by loading the coil with a head & shoulder phantom; B – A view of the transmit array model is shown to visualise the arrangement. Channels 1 to 8 are on the top row and 9 to 16 are on the bottom row, arranged one below the other.
  • Whole-body Metamaterial Liner RF Coil for 1H at 4.7 T with Reduced SAR Compared to Birdcage Coil
    Adam Maunder1, Ashwin Iyer2, and Nicola De Zanche1
    1Oncology, Medical Physics, Cross Cancer Institute, University of Alberta, Edmonton, AB, Canada, 2Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada
    At high-field strengths SAR safety regulations greatly limit sequence optimization with whole-body imaging. In simulation, the metamaterial liner presented here was found to produce 41% of the maximum 10g averaged SAR for the same transmit field relative to a comparable birdcage coil.
    Figure 5: Maximum intensity projections of SAR in axial, coronal and sagittal views normalized for 1 μT excitation within the volume outlined in the transmit efficiency maps (Figure 4). The location of the maximum SAR for both is indicated at the right arm, which is the body part nearest to the current-carrying conductors.
    Figure 2: Side-views of HFSS simulation models for (left) birdcage coil used as a standard for comparisons of MR transmission metrics and (right) metamaterial liner with human body model shown inside. Locations of transmission ports and dimensions are labelled.
  • Novel Setup for 31P MRSI of the Human Tongue In Vivo at 7T
    Ria Forner1, Kyung Min Nam1, Tijl van der Velden1, and Dennis Klomp1
    1UMC Utrecht, Utrecht, Netherlands
    3 receiver setups were successfully designed to provide 31P MRSI of the human tongue in-vivo. The external array showed somewhat less SNR than the loop coil revealing relatively high levels of phophomonoesters when compared to typical muscle spectra.   

    FIGURE 4: 31P MRSI results obtained from the external receiver coil in two subjects - also here PME is more intense, particularly in the first subject.

    FIGURE 3: 31P MRSI results obtained from the saddle and loop coils for the same subject. The observed SNR is highest with the loop coil, albeit that the signal may originate from the jaw muscle. For the saddle coil, in contrast to typically reported 31P spectra from muscle where PDE is higher than PME.
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Digital Poster Session - Innovative Transmit Coils
Engineering/Interventional/Safety
Monday, 17 May 2021 19:00 - 20:00
  • Design and evaluation of a 2-Tx 24-Rx coil for 5T knee MR imaging
    Shao Che1, Junjun Qin1, Shihong Han1, and Ye Li2
    1United Imaging Healthcare, Shanghai, China, 2Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Science, Shanghai, China
    A local transmit and receive knee coil is developed on the whole body 5T MRI scanner developed by United Imaging Healthcare. The phantom and human test yield promising image quality for knee imaging applications.
    Figure 1 Coil outer dimensions. (a)Side view: Legacy 12-Rx Knee Coil on UIH 3T system; (b, c) Side and front view: New 2-Tx 24-RX Knee Coil developed on UIH 5T system.
    Figure 5 Clinical scan for human knee.
  • In-vivo human brain imaging at 5 T using a 48 channel Tx-Rx array
    Ye Li1,2, Zidong Wei1,2,3, Shihong Han3, Shuheng Zhang3, Qiang He3, Xiaoliang Zhang4, Xin Liu1,2, and Hairong Zheng1,2
    1Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, 2Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen, China, 3United Imaging Healthcare, Shanghai, China, 4Department of Biomedical Engineering, State University of New York at Buffalo, NY, NY, United States
    The image quality at 5 T was largely improved comparing with 3 T, which indicated 5 T scanner’s potential in clinical and brain science applications. 
    Figure 3: Susceptibility weighted image (left) and zoomed in images (right) with 0.35*0.35*1.5 mm3 at 5T.
    Figure 2: Magnetic resonance angiography images acquired by TOF sequence with 0.6*0.6*0.6 mm3 resolution. (a) and (b) were acquired at 5T and 3T respectively using the same coils as in Figure 1.
  • An 8-channel transmit loop array for body imaging at 5T
    Fuyi Fang1, Wei Luo1, Jingxia Gong1, Rongxing Zhang1, Zidong Wei2, and Ye Li2
    1United Imaging Healthcare, Shanghai, China, 2Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China

    Body imaging at 5T: Comparison of the Transmitting performance of an 8 ch loop antenna and a 2ch birdcage

     

    Figure1: Two different coils are simulated; (a) A 2ch birdcage coil structure; (b) An 8ch loop coil structure.
    Figure2: RF simulation model of the 8ch loop coil used in CST-MWS loaded with an realistic human model (Gustav).
  • Robust decoupling of a 7 Tesla 8-channel loop array for head and cervical spinal cord imaging
    Bei Zhang1, Abbas Zaki2, Daniel Lowrance2, Ivan Dimitrov1,3, Binu Thomas1, Andreas Pfrommer4, and Anke Henning1,4
    1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, 2Erik Jonsson School of Engineering and Computer Science at The University of Texas at Dallas, Richardson, TX, United States, 3Philips Healthcare, Gainesville, FL, United States, 4Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
    A 7T 8-channel T/R array with robust decoupling performance for both head and cervical spinal cord imaging.
    Figure 4: MP2RAGE images of the head (resolution=1.0×1.0×1.0mm, 188 sagittal slices, SENSE=1.7(AP) × 1.7(RL), FA=5°, TR=6.2 ms, TE=2.0 ms, BW=162 Hz/pixel, and TA=6min41sec)
    Figure 2: S-parameter matrix of the 8ch array in simulation (a, b) and experiment (c)
  • Effect on SAR and Transmit Efficiency by Geometrical Configuration of RF Transmit Head Coil for 7 T MRI
    Youngdae Cho1 and Hyoungsuk Yoo1
    1Electronic Engineering, Hanyang University, Seoul, Korea, Republic of
    RF head coil with different configurations were simulated to analyze the impact of the geometrical shape of the coil on the transmit performance and SAR issues. The results show that a coil configuration similar to the head shape is required to optimize the transmit efficiency with allowable SAR.
    Figure 3. |B1+| field and SAR maps of the axial, coronal, and sagittal slices of the head depending on the coil configuration. Note that 3 μT and 8.0 W/kg was normalized to 0 dB for |B1+| field and SAR maps, respectively. The total input power of each configuration was scaled such that the peak of local SAR on the whole head was 8.0 W/kg.
    Figure 1. (a) Dimensions and components of the single MTL resonator. Simulated eight-channel MTL RF head coil of different configurations. Typical configuration and (b) adjusted configuration (1) with a circular shape, (c) configuration (2) with a elliptical shape, and (d) configuration (3) similar with the head shape.
  • A dipole antenna array with “flipped” high dielectric constant (HDC) material for improved SNR at 10.5 Tesla
    Myung Kyun Woo1, Lance DelaBarre1, Russell Lagore1, Steve Jungst1, Michael T Lanagan2, Thane Bonnett2, Qing X Yang2, Riccardo Lattanzi3, Kamil Ugurbil1, and Gregor Adriany1
    1Center for Magnetic Resonance Research, Minneapolis, MN, United States, 2Penn state University, Centre County, PA, United States, 3Radiology at NYU Grossman School of Medicine, New York University, New York, NY, United States
    Improved peripheral SNR was achieved for dipole antenna arrays with high dielectric constant (HDC) materials positioned away from the sample for UHF applications.
    Fig. 4 Simulation (a and b) and experimental (c and d) iSNR maps of the 8-channel HDC dipole antenna array of the “Normal” and “Flipped” setups.
    Fig. 5. Profile of the simulated (Blue, Red) and measured (Green , Purple) iSNR for Flipped and Normal setups. The location of the profiles is indicated as black dotted lines in Fig. 4 .
  • Development of a Dedicated Mono-surface 16-Element Transceiver Dipole Antenna Array for Parallel Transmission Cardiac MRI in Pigs at 7 Tesla
    Ibrahim A. Elabyad1, Maxim Terekhov1, Michael Hock1, David Lohr1, and Laura M. Schreiber1
    1Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
    The 16-element antisymmetric dipole array fits with the same dimensions as an 8-element straight dipole array. Anatomical T1-weighted images of the pig heart were acquired on a fresh cadaver (15min postmortem) at high spatial-resolution (0.5×0.5×4mm3).
    Figure 5. Slices of the short-axis view stack of the pig heart acquired post-mortem. The right panels show increased image slices marked red on the left panel. The LGE in the post-infarction scar is observed in the septal and anterior wall (arrows). Sufficient $$${B_1^+}$$$ field penetration and homogeneity without destructive interferences are achieved in the whole heart in both anterior-posterior and basal-apical directions.
    Figure 2. (a) Schematic of the mono-surface antisymmetric 16-element dipole antenna array with element dimensions, paring channels, and channel numbers with every two neighboring dipoles to form 8Tx-channels for the pTx system (8Tx/16Rx). (b) RF simulation model as simulated in CST-MWS of the new dipole antenna array loaded with a dedicated pig thorax phantom. (c)-(d) Prototypes of the dedicated pig thorax phantom and the antisymmetric dipole antenna array.
  • Design of a 19-Channel hybrid array system for Foot/Ankle Imaging at 7T
    Aditya Ashok Bhosale1, Leslie L Ying1, and Xiaoliang Zhang1
    1Biomedical Engineering, University at Buffalo, Buffalo, NY, United States
    Our study proposes 19-Channel hybrid array system for Foot/Ankle imaging.We were able to generate B1+ fields that could cover the areas of interest which are Heel,Ankle,Metatarsal region of the foot.  
    Fig.1. Simulation model showing the 19-channel hybrid array system a)Foot/Ankle phantom b)3D view of the phantom with RF coil system c) Front View of the system d) Side view of the system e) Back view of the system f) Top view of the system.
    Fig.2. B1+ field distribution along the transverse plane of the phantom. The transverse plane propagates from lower dimensions to higher dimensions. B) B1+ field distribution along the sagittal plane of the phantom at the center.
  • A 28-channel decoupled Tic-Tac-Toe transmit radiofrequency coil for 7T MRI
    Tales Santini1, Anthony DeFranco1, Tiago Martins1, Andrea Sajewski1, Howard J. Aizenstein1, and Tamer S. Ibrahim1
    1University of Pittsburgh, Pittsburgh, PA, United States
    We presented the uncoupled 28-channel transmit Tic-Tac-Toe coil design, which delivers high levels of B1+ homogeneity while maintaining low SAR characteristic of the design. The simulations were validated experimentally in a spherical phantom.
    The 28-channel Tic-Tac-Toe (TTT) RF transmit coil design. In a), the full model with 14 TTT panels shown with the Duke head model; in b), the coupled configuration of the TTT, with 4 channels per panel; in c), the uncoupled configuration, with 2 channels per panel; in d) the assembled TTT panel used in the experimental validation
    RF shimming with the 28-channel uncoupled TTT configuration (14 panels, as shown in Figure 1a); in a), several axial slices from below the brain stem to the top of the head and mid-sagittal and coronal slices. The simulations show homogeneous whole-brain coverage. In b), the maximum intensity projection of the SAR in axial, coronal, and sagittal planes respectively; in c), summary of the statistics. These are high values of homogeneity and SAR efficiency at 7T
  • A Comparative Study Highlighting a Novel UHF MRI Volume Body Coil Design
    Sayim Gokyar1, Henning U. Voss1, Victor Taracila2, Fraser J. L. Robb2, Douglas J. Ballon1, and Simone Angela Winkler1
    1Radiology, Weill Cornell Medicine, New York, NY, United States, 2General Electric Healthcare, Aurora, OH, United States
    The proposed body-sized 2D c-HPL architecture promises a new volume body coil design for UHF MRI comparable to the built-in designs at 3T. In comparison with existing birdcage (though not functional) and TEM designs it exhibits lowest SAR as well as lowest B1+ inhomogeneity and SAR efficiency.
    Figure 1. Different body coil architectures. (a) TEM Coil, (b) birdcage coil, and (c) 2D c-HPL coil. All coils have a shield length of 1 m and a shield diameter of 66 cm. Coils have the same length (L) of 33 cm in longitudinal direction and diameter (D) of 60 cm.
    Figure 3. In silico SAR maps of volumetric body coils. Phantom results (top row) were used to calculate the SAR efficiencies and realistic body model results (bottom row) were used to verify the previous results. Color-bars are normalized to 0.1 W/kg.
  • Asymmetric ring birdcage coil for volume excitation
    Hideta Habara1 and Shinichiro Suzuki1
    1Healthcare Business Unit, Hitachi, Ltd., Tokyo, Japan
    Design of asymmetric ring diameter birdcage volume coil has been studied by electromagnetic filed simulations.  Increasing the gap between the ring and the RF shield has an advantage in efficiency even applied on one side of the ring.
    Fig.1. Side view of the asymmetric ring and asymmetric gap birdcage coil. The front side ring has the larger diameter and narrower gap to the RF shield.
    Fig.3. B1+ amplitude line profile for the model (B) and (C) at the coronal plane and X=20 cm along the head-feet direction. Uniformity between Z=±10 cm greatly improved by taking the design of asymmetric ring width in the model (C).
  • Toward Enhanced Transmit Performance of Rectangular Dielectric Resonator Antenna Arrays for 7-T MRI Using Loop/Dipole Coupling Scheme
    Daniel Wenz1,2
    1CIBM Center for Biomedical Imaging, Lausanne, Switzerland, 2Animal Imaging and Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
    Loop-dipole coupling scheme, which can excite orthogonal dielectric modes in a rectangular dielectric resonator antenna arrays, provides significant transmit performance gains when compared to a dipole-only coupling scheme.
    Fig. 4. Transmit performance of the 8-channel dipole-fed rectangular dielectric resonator (RDR) array compared with the 16-channel loop-dipole coupled RDR array (circularly polarized mode). The 16-channel array yielded significantly higher B1+ (+35%) and SAR (+9%) efficiency in the center of the spherical phantom.
    Fig. 2. Phantom measurements: MR images obtained for a single-element loop- and loop-dipole-coupled rectangular dielectric resonator antenna. Three different profiles were selected and signal intensity as a function of distance was shown below.
  • Development of a Microstrip Tx Coil Module for 7T MRI
    Andrea N Sajewski1, Tales Santini1, Matthew Saich1, Tiago Martins1, and Tamer S Ibrahim1
    1University of Pittsburgh, Pittsburgh, PA, United States
    A microstrip RF coil was designed based on the Tic-Tac-Toe (TTT) concept. Simulations show similar B1+ distributions between the microstrip TTT and standard TTT coils, and experimental data helps to validate the simulations.
    Figure 3: Distribution of B1+ fields over a spherical phantom, shown as flip angle (FA) per 500V input: a) simulation of standard TTT panel, b) simulation of microstrip TTT panel, c) experimental B1+ map of microstrip TTT panel. Dashed lines in (a, b) show central slices used in Figure 4.
    Figure 1: a) standard Tic-Tac-Toe (TTT) panel, b) microstrip TTT panel, both 4.25in x 4.25in
  • New commercial 8Tx/16RX array for Clinical 7T Cardiac MRI: initial experience
    Maxim Terekhov1, David Lohr1, Theresa Reiter2, Ibrahim A. Elabyad1, Michael Hock1, and Laura M. Schreiber1
    1Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Comprehensive Heart Failure Center, Wuerzburg, Germany, 2Department of Internal Medicine I, Cardiology, University Hospital Würzburg, Wuerzburg, Germany
     We present the initial experience of using a commercial version of the 8Tx/16Rx thorax array operating in the pTX-Compatibility Mode of the scanner for cardiac MRI at 7T.       
     
    Figure 2 Long and short-axis view of the heart acquired at different flip-angles with both arrays. A pronounced appearance of blood-flow induced artifacts is observed with the new array, probably due to lower B1-gradients in the anterior-posterior direction.
    Figure 5 Result from optimized B1-vectors calculations. Panels (a) and (b) show the B1-field on the "Duke" model in the transversal and sagittal slices respectively. A sufficient penetration depth with better coverage of the posterior heart (lung and heart contours are shown) is predicted by these simulations for future measurements.
  • High power RF amplifier for UHF MRI with configurable number of channels
    Jifeng Chen1,2, Ye Li1, Han Zhang2, Bin Cao2, Xin Liu1, Hairong Zheng1, and Xu Chu2
    1Lauterbur Imaging Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, 2United Imaging Healthcare, Shanghai, China
    This work presents a RFPA design method for a UHF MRI system that supports pTx up to 8 channels which can be configured into independent mode (8 Channel) or combined mode (1/2/4 Channel) for different types of coil set-ups.
    Figure 1: Multi-channel RFPA for UHF MRI
    Figure 2: Pre-distortion algorithm
  • Quadrature Tx/Rx wireless coil for targeted breast MRI at 1.5 T
    Viktor Puchnin1, Anna Hurshkainen1, Anton Nikulin2, Georgiy Solomakha1, Anna Andreychenko1,3, and Alena Shchelokova1
    1Department of Physics and Engineering, ITMO University, St. Petersburg, Russian Federation, 2Institut Langevin, ESPCI Paris, CNRS, PSL University, Paris, France, 3Research and Practical Clinical Center for Diagnostics and Telemedicine Technologies of the Moscow Health Care Department, Moscow, Russian Federation
    We demonstrate for the first-time a quadrature transceive wireless coil that improves body coil transmit efficiency, SAR efficiency, and receive performance for the targeted area of the human breast.
    FIGURE 1: Numerical setups: the voxel model placed inside the body birdcage coil with M-coil (a), H-coil (b), and MH-coil (c) placed around the breast.
    FIGURE 3: Numerically calculated B1+ (a–c) and SARav.10g (d–f) maps for the voxel model placed inside the birdcage coil without (a,d) and with the MH-coil. The root mean square |B1+| value was calculated for the breast volume. (d-f) SARav.10g distributions are plotted through the local SAR maximum plane. The white circles indicate local SARav.10g maxima.
  • Circularly polarized coil for 1.5 T MRI RF harvesting
    Pavel Seregin1, Georgiy Solomakha1, Egor Kretov2, Oleg Burmistrov1, and Alexey Slobozhanyuk1
    1The Department of Physics and Engineering, ITMO University, Saint Petersburg, Russian Federation, 2Max Delbruck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
    In this work, we demonstrate a new circularly polarized (CP) volumetric coil design for energy harvesting in a 1.5 T MRI scanner and evaluated its performance at various locations along the B0 field axis inside the bore and during the different MR pulse sequences.
    Figure 1. a) Photo of the prototype of the volumetric harvesting coil and b) its circuit diagram.
    Figure 3. Influence of the pulse sequence type on the harvested power at the same Vadj =180 V, with default FA and load resistor 500 Ohm.
  • Development of Microstrip Coils Integrated with High Dielectric Constant (HDC) Material to Improve B1 Field and Performance of 1H MR imaging at 7T
    Soo Han Soon1,2, Matt Waks1, Xiao-Hong Zhu1, Hannes M. Wiesner1, Navid P. Gandji3, Qing X. Yang3, Michael T. Lanagan4, and Wei Chen1
    1CMRR, Department of Radiology, University of Minnesota, Minneapolis, MN, United States, 2Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States, 3CNMRR, Department of Neurosurgery, Penn State University, Hershey, PA, United States, 4Department of Engineering, Penn State University, Hershey, PA, United States
    The design of the human head 1H RF coil based on the integrated HDC-MTL transceiver array approach shows promise for significantly improving the B1 efficiency and imaging sensitivity at 7T.
    Fig. 3. Estimated B1+ maps of Slice 28 (marked with red boxes in Fig. 2A, 2B) in CP mode (A) and B1-shimmed mode (B). The averaged B1+ fields of all voxels in Slice 28 with the HDC-MTL transceiver array (right panels) were 2.1 times and 1.4 times higher than those with the control array (left panels). 1D profiles of selected voxels (red lines in 3A and 3B) of Slice 28 in CP mode (C) and in B1-shimmed mode (D) showed significant B1+ improvement and enhanced penetration depth after B1 shimming.
    Fig. 4. Estimated relative B1- maps of 36 imaging slices covering > 10 cm in the middle of the head-shaped phantom (A); and Slice 28 (marked with red boxes in Fig. 4A) B1- map (B) with the HDC-MTL transceiver array and the control array in the B1-shimmed mode. The 1D profiles of selected voxels (red lines in 4B) showed significant improvement of the B1- field with the HDC-MTL transceiver array, especially in the periphery areas.
  • A 2D High-Pass Ladder RF Coil Architecture for UHF MRI
    Sayim Gokyar1, Henning U. Voss1, Victor Taracila2, Fraser J. L. Robb2, Michael Bernico3, Douglas Kelley3, Douglas J. Ballon1, and Simone Angela Winkler1
    1Radiology, Weill Cornell Medicine, New York, NY, United States, 2General Electric Healthcare, Aurora, OH, United States, 3General Electric Healthcare Technologies, Waukesha, WI, United States
    We demonstrate feasibility of the 2D c-HPL concept at 7T. Simulation results show 25% reduced SAR and 45% increased B1+ homogeneity as compared to the birdcage concept. First in vitro images in quadrature mode demonstrate functional operation and agree with simulations.
    Figure 2. A selection of mode distributions of the proposed 4 × 8 c-HPL coil, where each mode occurs at a different frequency due to mutual coupling. Here, mode (1,4) occurs at the lowest frequency with a higher spatial variation among others. Mode (1,1) is tuned to 298 MHz and showed the best B1+ uniformity.
    Figure 1. (a) A 16-leg high-pass birdcage coil, (b) a 2D cylindrical high-pass ladder (2D c-HPL) coil array (4 × 8). Both coils are loaded with a spherical phantom at isocenter and driven with an accepted RF power of 1W.
  • Performance comparison of using an external 16-channel transmit array vs. using 16 elements of a 32-channel receive array as transceivers at 10.5 T
    Bei Zhang1, Gregor Adriany2, Navid Pourramzan Gandji3, Qing X. Yang3, Brian Rutt4, Jeramie Radder2, Lance DelaBarre2, Myung Kyun Woo2, Kamil Ugurbil2, and Riccardo Lattanzi5,6
    1Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States, 2Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States, 3Department of Radiology, Pennsylvania State College of Medicine, Hershey, PA, United States, 4Department of Radiology, Stanford University, Stanford, CA, United States, 5Center for Advanced Imaging Innovation and Research (CAI2R) and Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, 6The Vilcek Institute at NYU Langone Health, New York, NY, United States
    The additional complexity associated with constructing a multi-element transceiver array compared to using an external transmitter could be justified for 10.5T imaging by the expected gain in performance.
    Figure 1 Different transmit setups. 32-ch receive array with the 16 elements chosen as transceivers shadowed (a); external 16-ch transmit array with high-permittivity helmet (b); 32-ch receive array with HPM with the 16 elements chosen as transceivers shadowed (c). Note that in (b) the 32-ch array between the external transmit array and the HPM helmet is not shown for clarity. Simulations were repeated also for the transmit setup in (b) after removing the HPM helmet.
    Figure 2. B1+ divided by the square root of absorbed power for the four setups for three orthogonal sections at the center of the head. The 16 transmit elements were combined in CP mode. The HPM had a negligible effect for the case of the external transmit array.
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Digital Poster Session - Innovative Receive Coils
Engineering/Interventional/Safety
Monday, 17 May 2021 19:00 - 20:00
  • Ultra-Flexible, High-Resolution, 60-Channel RF Coil for Supine Breast Imaging
    Jana Vincent1,2,3, Clyve Konrad Follante1, Ersin Bayram4, Lloyd Estkowski5, Ty Cashen6, Mark Giancola1, Victor Taracila1, Yun-Jeong Stickle1, Lalit Rai1, Venkata Malasani1, Nicole Wake7,8, Vichiry Yan1, Robert Stormont9, Joseph Rispoli2,10, and Fraser Robb1
    1GE Healthcare Coils, Aurora, OH, United States, 2Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States, 3Basic Medical Sciences, Purdue University, West Lafayette, IN, United States, 4Global MR Applications & Workflow, GE Healthcare, Houston, TX, United States, 5Global MR Applications & Workflow, GE Healthcare, Waukesha, WI, United States, 6Global MR Applications and Workflow, GE Healthcare, Madison, WI, United States, 7Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, United States, 8Center for Advanced Imaging Innovation and Research, Department of Radiology, NYU School of Medicine, New York, NY, United States, 9GE Healthcare, Waukesha, WI, United States, 10School of Electrical & Computer Engineering, Purdue University, West Lafayette, IN, United States
    Here we present the first 60-channel, high resolution, lightweight, flexible, supine breast coil. The coil mitigates respiratory and motion artifacts through high acceleration which is made possible with a high channel count and commensurate SNR that, in turn, facilitates supine imaging.
    Figure 1. Complete breast/torso coil setup: (a) Front and (b) back mechanical assembly, (c-d) Coil assembly
    Figure 3. SSFSE, Left: acceleration factor of 3, Right: acceleration factor of 4. Improved sharpness is observed with higher acceleration due to reduced T2 blurring resulting from a shortened echo train. Arrow indicates region of fibroglandular tissue.
  • A Continuously Adjustable 32-Ch Head Coil Array for MRI at 3T
    Yunsuo Duan1, Jiacheng Wang2, Feng Liu1, Rachel Marsh1, and Thomas J. Vaughan3
    1MR Research, Department of Psychiatry, NYSPI and Columbia University, New York, NY, United States, 2Department of Electrical Engineering, New York University, New York, NY, United States, 3ZMBBI, Columbia University, New York, NY, United States
    we presented a novel partially flexible 32-ch coil array to address the difficulty in close fitting for various human head sizes. The coil array worked well within size range of 180mm x 220mm to 220mm x 260mm, which fits for almost all human subjects,  while maintaining desirable comfort.  
    Figure 1. (a) 3D design of the coil former. The upper part (top) is detachable from the lower part for size adjustment. The Top and base are 3D printed using rigid PLA filaments. The sidewalls are 3D-printed using semi-flexible filaments TPU so the sidewalls can be pulled inwards-outwards to shrink/extend the size of the coil. (b) Schematic circuit design of individual coil loop. Ct=15-40pF, Cm=33pF, Cd=24pF, Cc=8.2pF.
    Figure 2. (a) The coil adjusted to 180mmx 220mm and loaded with a sphere phantom in a diameter of 180mm; (b) The coil adjusted to 220mm x 260mm and loaded with the same phantom. (c) A axial-plane image acquired with coil setting (a); (c) A axial-plane image acquired with coil setting (b); (e) SNR distributions along the horizontal center line of image (c) (red) and image (d) (blue).
  • A Quadrature Birdcage/47Rx Coil Array for Acceleration Images on 3 T MRI
    Jo Lee1,2, Sen Jia1,2, Liu Liu3, Xiaoliang Zhang4, and Ye Li1,2
    1Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, 2Shenzhen Key Laboratory for MRI, Shenzhen, China, 3United Imaging Healthcare, Shanghai, China, 4Department of Biomedical Engineering, State University of New York, Buffalo, NY, United States
    We designed a quadrature-birdcage/ 47Rx head coil array for accelerated images on 3 T MRI, and has compared to a commercial 32-channel head coil for quantified analysis. The results show that the 47-channel head coil has better acceleration ability.
    Fig.3. 0.6 mm isotropic modulated flip angle technique in refocused imaging with extended echo train (MATRIX) images were acquired using the commercial head coil (32ch; top row) and the quadrature birdcage/47Rx coil array (47ch; bottom row) at R = 7-fold acceleration. The acceleration direction was on phase encoding and slice phase encoding. H = head; P = posterior; R = right; A = anterior.
    Fig.2. Inverse g-factor maps. To display coil acceleration ability of each direction, each orientation was accelerated on different directions. Transverse orientation: Left-to-Right acceleration direction. Sagittal orientation: Anterior-to-Posterior acceleration direction. Coronal orientation: Head-to-Feet acceleration direction. Regions of interest (ROIs) is marked as black dashed line. The mean g-factor value of each ROI is written beside the related image. L: left, R: right, A: anterior, P: posterior, H: head, F: feet.
  • A dedicated coil for cerebellar fMRI
    Nikos Priovoulos1, Thomas Roos1, Ozlem Ipek2, Ettore Meliado3, Richard Nkrumah2, Dennis Klomp3, and Wietske van der Zwaag1
    1Spinoza Center, Amsterdam, Netherlands, 2King’s College London, London, United Kingdom, 3University Medical Center Utrecht, Utrecht, Netherlands
    The combination of 32Rx dense surface receives with a dedicated 3Tx transmit results in increased B1+, SNR and BOLD sensitivity in the human cerebellum at 7Tesla.
    Figure 5: A, (Finger tapping > Rest) BOLD fMRI significant clusters (z>3.1) for 2 sample participants along axial slices at the height of the cerebellum, crossing the hand region in cerebellar lobule V (left) and cerebellar lobule VIII (right). B, Group Z-stat distribution for each coil. C, Barplots of active voxels at group level in relation to the distance from the skull.
    Figure 1: A, view of the cerebellar coil. Red, transmit elements. Blue, receive elements. B, The transmit array (housing partially removed). C, The receive array (open covers). D, Distribution of voxels in the cerebellum with respect to distance from the skull (median distance=2.58cm (dotted line)). E-G, 3D-EPI slices. E, Head coil without B1 shimming. F, Head coil after B1 shimming. G, Cerebellar coil. Note the reduced deeper sensitivity deeper due to the small total surface area.
  • A novel multi-turn histology RF coil design for micro-histological slide imaging
    Byung-Pan Song1,2, Sung-Jun Yoon1, Hyeong-Seop Kim1,2, Kyoung-Nam Kim3, and Seung-Kyun Lee1,2,4,5
    1Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of, 2Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Korea, Republic of, 3Department of Biomedical Engineering, Gachon University, Incheon, Korea, Republic of, 4Department of Physics, Sungkyunkwan University, Suwon, Korea, Republic of, 5IBS Center for Neuroscience Imaging Research, Suwon, Korea, Republic of
    We propose a new multi-turn histology coil for imaging microscopic histological tissue with a higher SNR than previous coil designs.
    Figure 1. The pictures of the coils and their schematics. a) U-shaped coil , b) 3-turn solenoid coil, c) 8-turn solenoid coil. d,e) Schematics of the U-shaped coil and a solenoid coil. e) is citation from reference[4]. Cm and Ct enable fine adjustment of the coil impedance matching and resonance frequency tuning
    Figure 4. The images of a 40 μm-thick rat brain slice. a) U-shaped coil, b) 3-turn solenoid coil, c) 8-turn solenoid coil. The signal value was measured in the red square region, and the noise value was measured in the yellow rectangle. The color scale was adjusted for each image.
  • How far Should Coil Coverage be Extended to Reach Optimum Simultaneous Multi-Slice Acceleration in Cardiac MRI?
    Anpreet Ghotra1, Sam-Luca JD Hansen1, Robin Etzel1, Mirsad Mahmutovic1, Alina Scholz1, Nicolas Kutscha1, Matthäus Poniatowski1, Markus W May1, Choukri Mekkaoui2, and Boris Keil1
    1Institute of Medical Physics and Radiation Protection, TH Mittelhessen University of Applied Sciences, Giessen, Germany, 2Harvard Medical School, Massachusetts General Hospital, Department of Radiology, A.A. Martinos Center for Biomedical Imaging, Boston, MA, United States
    64-channel coil arrays with extended coverage provide more sufficient encoding capacity in SMS-accelerated cardiac imaging than arrays that compactly enclose the cardiac region. 
    Modelled and simulated circular overlapped coil arrays for highly SMS accelerated cardiac images.
    Inverse g-Factor maps of a representative sagittal slice through the heart. g-factors were derived from axial SMS accelerations with multiband factors 4, 6, 8, and additionally combined with in-plane accelerations of R=2 and R=3. The heart region was covered by 60 slices of 2 mm each. 15, 10, and 8 collapsed slices were needed to reconstruct the full heart for MB=4, MB=6, and MB=8, respectively.
  • A novel 16 channel flexible coil for highly accelerated upper-airway MRI
    Wahidul Alam1, Rushdi Zahid Rusho1, Scott Reineke2, Madavan Raja2, Stanley Kruger3, Joseph M. Reinhardt1, Junjie Liu4, Douglas Van Daele5, and Sajan Goud Lingala1,2
    1Roy J Carver Department of Biomedical Engineering, University of Iowa, iowa city, IA, United States, 2ScanMed LLC, Omaha, NE, United States, 3Department of Radiology, University of Iowa, iowa city, IA, United States, 4Department of Neurology, University of Iowa, iowa city, IA, United States, 5Department of Otolaryngology, University of Iowa, iowa city, IA, United States
    We develop a novel custom airway coil to offer significant boost in signal sensitivity in several upper-airway regions. The coil exhibits robust parallel MRI performance up to R=4~5 fold 1-D under-sampling for static imaging, and highly accelerated dynamic imaging (up to R~27 fold).
    Fig.5 (animation): 2D concurrent multi-slice accelerated dynamic imaging of swallowing an ~10 ml bolus of pineapple juice. Non-Cartesian spiral under-sampling at ~27 fold acceleration level was combined with a sparse SENSE reconstruction scheme. The transport of the bolus is robustly captured in the three sagittal slices with adequate spatial resolution (2.4 mm2), and temporal resolution (17.1 ms).
    Fig.2: (a) Individual coil images from the 16 channel elements and (b) the R=1 SENSE coil combined image using the proposed airway coil. The coil offers high sensitivity in all upper-airway regions of interest (eg. lips, tongue, hard palate, soft palate, epiglottis, glottis).
  • Signal-to-noise of thermal versus hyperpolarized MRI as a function of field strength and receive coil temperature
    Mohammed M. Albannay1, Charles McGrath1, Alexander Jaffray1, and Sebastian Kozerke1
    1University and ETH Zurich, Institute for Biomedical Engineering, Zurich, Switzerland
    SNR of thermal and hyperpolarized MRI is simulated based on first principles. Hyp. nuclei detection at low field strengths prolong T2* thus reduce readout bandwidth, leading to higher SNR compared to clinical field strengths. SNR gains from coil cooling are studied experimentally at 0.75T
    (A) Geometry of the three used receive coils with measured inductance and resistance using a vector network analyser at 32 MHz. The multi-loop coil is printed on 1.6 mm FR4 (1 oz copper), while loop coils are made from $$$(\oslash2 mm)$$$ copper tubing. (B) The coils were hosted in a Styrofoam box and laid parallel to the box surface. Separation $$$g = 2$$$ cm. The phantom was positioned adjacent to a $$$(\oslash5 cm)$$$ transmit coil, under a plastic arc.
    (A) Normalized simulated SNR for thermal and (B) hyperpolarized MRI as a function of field strength and coil temperature, (C) Ratio between equivalent sample and coil resistance. (D) Potential SNR gain relative to 300 K receiver coil at 3T for hyperpolarized MRI. All simulations consider a $$$\oslash$$$ 10 cm coil constructed from $$$\oslash $$$ 2 mm copper wire placed directly on the phantom. Inset dashed line indicating 0.75T.
  • Performance comparison of a 10 cm single-gap vs. double-gap coaxial coil used as a transceiver for 7T MRI
    Lena Nohava1,2, Andre Kuehne3, Elmar Laistler1, and Sigrun Roat1
    1High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria, 2BioMaps (Laboratoire d'Imagerie Biomédicale Multimodale Paris Saclay), Université Paris-Saclay, CEA, CNRS, Inserm, Orsay, France, 3MRI.TOOLS GmbH, Berlin, Germany
    For 7T MRI, 10 cm double-gap coaxial coil design operated at its self-resonance is advantageous for increased Tx efficiency and slightly lower SAR. Orientation independence of the coil’s B1-field is of importance for free positioning of flexible wearable arrays.
    Figure 4: Measured and simulated B1+/√P maps in the central sagittal and transversal slice (FOV=256x256mm2, 0.5x0.5mm2 in-plane resolution, 1.5mm slice thickness, Vref=150V). Different orientations are indicated by black or green dots: their location corresponds to the coil conductor position and their size indicates the oCo current density (inhomogeneous for the 1G, homogeneous for the 2G coil). Thin black lines in transversal measured maps mark the boundaries of regions where the flip angle was higher than the dynamic range of the mapping technique.
    Figure 1: (a) Schematic showing gap positioning, (b) photographs of fabricated coils and interface circuit, (c) coaxial cable cross section, (d) phantom photo and investigated coil orientations.
  • Additive manufacturing of MRI coils by printing and electroplating a conductive polymer
    Christoph Michael Schildknecht1 and Klaas Paul Pruessmann1
    1Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zürich, Switzerland
    This work reports additive manufacturing of MRI coils based on 3D printing and electroplating of conductive polymer. The proposed approach greatly simplifies the fabrication of complex coil and array geometries with a high degree of accuracy and reproducibility.
    The process has three major steps. First, the design is made in a CAD software. Then the part is 3D printed and finally the conductive polymer is electroplated with copper to increase its conductivity.
    In the top row are renderings shown for the intended wrist coil. In the bottom row is the actual 3D printed and electroplated coil displayed. Not only does the fabricated coil look similar as in the renderings, they also closely match the geometrical dimension as specified in the CAD.
  • Novel antenna array for ultra-high field MR-PET
    Chang-Hoon Choi1, Suk-Min Hong1, Jörg Felder1, Lutz Tellmann1, Jürgen Scheins1, Elena Rota Kops1, Christoph Lerche1, and N. Jon Shah1,2,3,4
    1INM-4, Forschungszentrum Juelich, Juelich, Germany, 2JARA-BRAIN-Translational Medicine, Aachen, Germany, 3Department of Neurology, RWTH Aachen University, Aachen, Germany, 4INM-11, Forschungszentrum Juelich, Juelich, Germany
    This novel J-pole antenna array is a unique MRI RF probe with exceptionally low gamma attenuation, allowing simultaneous MR-PET and MR-SPECT experiments to be conducted without compromising any aspects of system performance and image quality compared to the stand-alone instrumentation.
    Figure 1. A photograph of the proposed, multi-channel J-pole antenna array showing its essential parts and components.
    Figure 3. Attenuation maps of the proposed J-pole array (left) and the reference array (right). The centre part of the antennas was measured.
  • Decomposition of the incomplete volume-surface integral equation matrices for MR coil simulations
    Ilias Giannakopoulos1, Georgy Dmitrievich Guryev2, Jose Enrique Cruz Serralles2, Ioannis Georgakis1, Luca Daniel2, Jacob White2, and Riccardo Lattanzi1,3,4
    1Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, NY, United States, 2Department of Electrical & Computer Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, 3The Bernard and Irene Schwartz Center for Biomedical Imaging (CBI), Department of Radiology, New York University Grossman School of Medicine, New York, NY, United States, 4Vilcek Institute of Graduate Biomedical Sciences, New York University Grossman School of Medicine, New York, NY, United States
    The volume-surface integral equation coupling matrix, that models the interactions between radiofrequency coils and tissue, is reshaped to a set of incomplete tensors and compressed with the canonical model. Results show 35 times compression for an error less than 2%, at a 7 T MRI simulation.
    Figure 4: Qualitative comparison between the simulated B1+ maps, for one representative coil element of the array and the middle sagittal slice. The results for the incomplete and full matrix are displayed for three canonical ranks (4,10,16), along with the relative error with respect to the ground truth (left) in logarithmic scale. Voxels outside the scatterer are masked for enhanced visualization.
    Figure 3: Overall compression factor (left axis) and relative error (right axis), for the full and incomplete matrices and various canonical ranks.
  • Flexible Body Coil for Vertical Field MRI using Loop/CRC RF Coil Array
    Yosuke Otake1, Takeshi Taniguchi1, Hideta Habara1, Christophor Napier2, Errol Brissett2, Shawn Etheridge2, Masayoshi Dohata1, and Kazuyuki Kato1
    1Healthcare Business Unit, Hitachi, Ltd., Tokyo, Japan, 2Hitachi Healthcare Americas, Twinsburg, OH, United States
    To improving the SNR and the usability in the vertical field MRI, a flexible body coil using  loop/CRC multi-channel array has been developed. SNR of the developed coil 46% better than  a conventional coil. This technique will contribute to improve the performance of the vertical field MRI.

    Figure 1. Coil arrangements. (a)Basic configuration of loop/CRC hybrid multi channel array (LCA) RF coil.(b)Developed torso coil using LCA(8ch). (c)Developed spine coil using LCA(8ch). (d)Conventional body coil for a vertical field MRI(6ch).

    Figure 3. Phantom experiment at 1.2T vertical field MRI. (a)Developed body coil (LCA torso and spine). (b)Conventional body coil(SSCA).
  • Design of an over-overlapped wearable 3T pelvic phased array using a capacitor-terminated coaxial coil
    Ming Lu1,2, Junzhong Xu1,2, Sandeep S. Arora3, John C. Gore1,2, and Xinqiang Yan1,2
    1Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, 2Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, 3Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, United States
    Based on our simulation results, the Capacitor-Terminated Coaxial (CTC) coil is the best candidate for prostate imaging where a wearable, size-optimized, high-density array is desired.
    Figure 4 A and B: Simulated receive sensitivity (B1-) maps in the central axial slice of a cuboid phantom (15x30x15 cm3), with one coil set to 1W input (active) and the other coil terminated with the preamplifier loading (passive). The B1- distortion due to non-perfect decoupling can be easily observed in the residual B1- maps calculated by subtracting the baseline B1- of a single coil. C and D: Plots of normalized B1- values at the 10-cm-deep region (white dotted circle in Figures 4A and B).
    Figure 5 Illustration of an example of a 29-element high-density over-overlapped coil array focusing on prostate imaging. A: Planar unfold view. B and C: Three-dimensional view.
  • An Integrated Radio-Frequency/Wireless (iRFW) Coil Design for Wireless Q-Spoiling During MR Imaging
    Jonathan Cuthbertson1,2, Trong-Kha Truong1,2, Jasmine Chen1,2, Fraser Robb3, Allen W. Song1,2, and Dean Darnell1,2
    1Medical Physics Graduate Program, Duke University, Durham, NC, United States, 2Brain Imaging Analysis Center, Duke University, Durham, NC, United States, 3GE Healthcare, Aurora, OH, United States
    The experiments performed showed that the integrated RF/wireless coil was able to provide wireless Q-spoiling during MR image acquisition without significantly impacting SNR or wireless performance.
    Figure 1: RF currents flow on the integrated RF/wireless coil design for simultaneous MR image acquisition (red) and wireless data transfer (orange), while a DC voltage (blue) is applied to the PIN diode from a GPIO pin from the Wi-Fi transceiver module for Q-spoiling.
    Figure 3: Gradient-echo EPI mean images, SNR maps of the mean images, and temporal SNR (TSNR) maps of the image time series acquired in a water phantom, showing no degradation in image quality for wireless Q-spoiling using the iRFW coil compared to conventional wired Q-spoiling.
  • Universally Sized, High-Resolution and ASSET Optimized AIR Cervical Coils Combined with a 48-Channel Head Coil for 3T MRI
    Yun-Jeong Stickle1, Clyve Konrad Follante1, Mark Giancola1, David Anderson1, Fraser Robb1, Thomas Stickle1, Robert Stormont2, Holly Blahnik2, Ho-Joon Lee3, Young Han Lee4, and Darryl B. Sneag5
    1GE Healthcare Coils, Aurora, OH, United States, 2GE Healthcare, Waukesha, WI, United States, 3Haeundae Paik Hospital, Busan, Korea, Republic of, 4Severance hospital, Yonsei University, Seoul, Korea, Republic of, 5Hospital for Special Surgery, New York, NY, United States
    This study shows results for two different universally sized AIR (Adaptive Imaging Receive) neck/cervical spine coils combined with a 48-Channel head coil to provide higher SNR and improved acceleration compared to a conventional coil.

    Fig. 1. Universally sized AIR 64-Channel phased array head neck coils for carotid, head/neck and cervical spine MRI (a) Prototype1 16-Channel neck/cervical spine anterior setup coil assembly with 48-Channel head coil (b) Prototype2 16-Channel neck/cervical spine posterior setup coil assembly with 48-Channel head coil

    Fig. 5. (a) Sagittal T2, 20 cm FOV, 2mm slice thickness image and (b) MRA images obtained with the protoytpe1 16-Channel neck/cervical spine coil with 48-Channel head coil. Axial reformatted images of the cervical spine from a 3-D CUBE T2-weighted FSE sequence (0.7mm isotropic) demonstrates improved SNR with the (c) protoytpe1 16-Channel neck/cervical spine coil with 48-Channel head coil compared to the (d) conventional coil. Note improved visualization of the intrathecal nerve rootlets (arrows) with the prototype1 coil.
  • Development of a multiplexed ERETIC-RF array coil for quantitative whole brain 3D-MR spectroscopic imaging (MRSI)
    Bijaya Thapa1,2, Bernhard Strasser1,2, Xianqi Li1,2, Jason Stockman1,2, Azma Mareyam1, Boris Keil3, Zhe Wang4, Stefan Carp1,2, Yulin V. Chang4, Lawrence Wald1,2, Philipp Hoecht Hoecht5, and Ovidiu Andronesi1,2
    1Dept. of Radiology, MGH, A. A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, 2Harvard Medical School, Boston, MA, United States, 3Mittelhessen University of Applied Science, Giessen, Germany, 4Siemens Medical Solutions USA, Charlestown, MA, United States, 5Siemens Healthcare, Erlangen, Germany

    An ERETIC method was integrated into 3D MRSI through the hardware and software for quantitative brain metabolite imaging and compared its result with the conventional internal water reference method. Bland-Altman plot plotted to compare them which shows good agreement between these methods.

     

    Fig3. Absolute Metabolite concentration map in mMol unit obtained from ERETIC (3rd column) and IWR (4th column) methods corresponding to the anatomical MEMPRAGE image (2nd column) and MEMPRAG image down-sampled to MRSI size (1st column ).
    Fig4. Bland-Altman plots corresponding to the metabolite concentration map shown in Fig.3, which indicates the agreement between IWR and ERETIC methods.
  • New approach to Improve Sensitivity of Implantable NMR microprobe through Electrical Modelization
    José Antonio BERNARDO1, Abel Rangel Trejo1, Lucas Werling2, Wilfried Uhring2, Luc Hebrard2, Youssef Zaim Wadghiri3, Christian Gontrand4, and Latifa Antonio Fakri-bouchet5
    1Univ Lyon, CNRS, Université Claude Bernard Lyon 1, Institut des Sciences Analytiques, UMR 5280, Villeurbanne, France, 2Icube Laboratory, UMR –CNRS 7357, Université de Strasbourg, Strasbourg, France, 3Grossman School of Medicine, New York University, New York, NY, United States, 4INL(Institut des nanotechnologies de Lyon), INSA (Institut National des Sciences Appliquées) Lyon, CNRS, Université Claude Bernard Lyon1, Villeurbanne Cedex, France, 5Univ Lyon, CNRS, Université Claude Bernard Lyon 1, Institut des Sciences Analytiques, UMR 5280, INSA Lyon (Institut National des Sciences Appliquées), Villeurbanne, France
    Through 3D-TLE platform, we can extract the microprobe electrical parameters and then provide a complete electric model. Thus, our original and accurate method aims to estimate the global resistive losses from geometrical parameters.
    \(Fig.1\). Block diagrams of the simulation methodology: TLE user interface to 3D microcoil model
    \(Fig.2\). The complete electric model of 3D NMR microcoil prototype
  • Exploring parallel imaging performance for prostate imaging at 7T using a 72-channel receive array
    Tijl van der Velden1, Mark Gosselink1, Ingmar Voogt2, Martijn Froeling1, Hans Hoogduin1, Dennis Klomp1, Bart Steensma1, and Alexander Raaijmakers1,3
    1UMC Utrecht, Utrecht, Netherlands, 2Wavetronica, Utrecht, Netherlands, 3Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
    An parallel imaging acceleration of a least a factor of 3 is feasible with a 72-channel body array at 7T.
    T2w images with SENSE 1 (left), 2 (center) and 4 (right). Bottom row shows magnification of the prostate. From an acceleration of 4 small artefacts are observed, as well as the expected reduction in SNR.
    3D T1w acquisition of the lower body. Left, no SENSE acceleration, right: 3x3 SENSE acceleration. Artefacts are predominately in the peripheral region of the body.
  • Coaxial coil modules as building blocks of individually arranged receive-only coil arrays
    Michael Obermann1, Sigrun Roat1, and Elmar Laistler1
    1High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
    A proof of principle for a truly modular ultra-lightweight multi-purpose flexible receive array made from coaxial coil elements was demonstrated by showing three 4-channel modules arranged in different array configurations.
    Fig. 1: 4-ch coaxial coil module. The compact cylindrical housing (diameter = 5.2 cm, height 3.2 cm) surrounds the PCBs with all electrical components and four preamplifiers.
    Fig. 2: a) Differently arranged 12-ch layouts built from the same modules M1, M2 and M3. b) MR images (GRE2D) acquired on a flat phantom in a slice at a distance of 5 cm to the coil arrays. The distance from the arrays to the phantom is around 5 mm.