View Presentation Video

Neha Koonjoo^1,2, Torben P.P Hornung^1,2,3, Susu Yan^3,4, Matthew S Rosen^1,2,5, and Thomas R Bortfeld^3,4
1Department of Radiology, A.A Martinos Center for Biomedical Imaging / MGH, Charlestown, MA, United States, ²Harvard Medical School, Boston, MA, United States, ³Department of Physics, ETH Zürich, Zürich, Switzerland, ⁴Department of Radiation Oncology, MGH, Boston, MA, United States, ⁵Department of Physics, Harvard University, Cambridge, MA, United States

Keywords: Low-Field MRI, Breast, Hybrid & Novel System Technology

The use of low field MRI guidance in proton therapy is a new area of research especially during treatment of breast cancer. In this study, we optimized and constructed five different breast/chest RF coils at low field as proof of concept for a future MR guided proton therapy system design. Different coil shapes and sizes were tested. Organs-at-Risk (OAR) and different anatomical regions were optimized for imaging. Using the five coils, phantom images were acquired at 6.5 mT and MR signal across slices were compared to the calculated optimized B₁ field homogeneity. Human breast imaging was also carried out.

Yi Yi¹, Zhonghai Chi², Yakui Wang¹, Maopeng Wu², Lixue Wang¹, Deqing Jiang¹, Li He¹, Xihai Zhao³, Yonggang Meng², Ji Zhou⁴, Qian Zhao², and Zhuozhao Zheng^1
1Department of Radiology, Beijing Tsinghua Changgung Hospital, School of Medicine, Tsinghua University, Beijing, China, ²State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, China, ³Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China, ⁴State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China

Keywords: New Devices, Non-Array RF Coils, Antennas & Waveguides, Metasurface

Metasurface is an effective solution to enhance SNR of MRI images. Here, we propose a wireless and passive metasurface coil and evaluate its performance in knee MRI. Phantom studies suggest improved image uniformity compared to the conventional phased-array radio-frequency coils. In vivo knee MRI of volunteers suggests higher image quality scores and better contrast of knee cartilage in metasurface groups. When used in conjunction with the spine coil, the metasurface coil provides a favorable SNR between that of the 4- and 12-channel phased-array coil. It is more convenient, cost-effective, and applicable to 1.5T MRI systems from different manufacturers.

View Presentation Video

Vladislav Koloskov¹, Mikhail Zubkov¹, Georgiy Solomakha¹, Viktor Puchnin¹, Anatoliy Levchuk^1,2, Alexander Efimtcev^1,2, Irina Melchakova¹, and Alena Shchelokova^1
1School of Physics and Engineering, ITMO University, St. Petersburg, Russian Federation, ²Department of Radiology, Federal Almazov North-West Medical Research Center, St. Petersburg, Russian Federation

Keywords: Hybrid & Novel Systems Technology, Hybrid & Novel Systems Technology, high permittivity materials, SNR enhancement

We show that high permittivity materials (HPMs) can improve functional magnetic resonance imaging (fMRI) at 1.5T, increasing the receive sensitivity of a commercial multi-channel head coil. Both numerical simulations and experiment showed ~25% improvement in the signal-to-noise ratio (SNR) of a commercial head coil in the areas of interest when HPM blocks were placed in proximity. This led to an increase in the detected motor cortex fMRI activation volume by an average of 56%, thus resulting in more accurate functional imaging at 1.5T.

Yakui Wang¹, Zhonghai Chi², Yi Yi¹, Maopeng Wu², Lixue Wang¹, Deqing Jiang¹, Li He¹, Xihai Zhao³, Yonggang Meng², Ji Zhou⁴, Qian Zhao², and Zhuozhao Zheng^1
1Department of Radiology, Beijing Tsinghua Changgung Hospital, School of Medicine, Tsinghua University, Beijing, China, ²State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, China, ³Center for Biomedical Imaging Research, Department of Biomedical Engineering,School of Medicine, Tsinghua University, Beijing, China, ⁴State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China

Keywords: Non-Array RF Coils, Antennas & Waveguides, Joints, Metasurface

We designed a wireless metasurface resonator(WMR) for wrist magnetic resonance imaging(MRI) at 1.5T and tested the imaging effect. Phantoms and 14 wrist jionts(7 healthy volunteers) were examed with T1W SE and fat-suppressed PDW FSE sequences at a 1.5T MRI system. Commercial 12-channel wrist array coil(12CH-WR) and WMR(coupling with integrated spine coil) were used to receive MR signal respectively. We found that WMR could improve the image SNR by 1.5~2 times, and significantly improve the image contrast compared with the traditional 12CH-WR.

View Presentation Video

Lauren Smart¹, Adam Mitchell Maunder², Ashwin K. Iyer¹, and Nicola De Zanche^2
1Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada, ²Oncology, Medical Physics, University of Alberta, Edmonton, AB, Canada

Keywords: RF Arrays & Systems, Body, metamaterial

Abdominal and thoracic imaging at 3T suffers from inhomogeneous transmit fields and hot-spots in specific absorption rate (SAR) that limit image quality and imaging efficiency, respectively. We combine a lightweight metamaterial and metasurface (the ‘metaslab’) to enhance transmit efficiency and homogeneity, as well as to reduce SAR. The metaslab is further able to operate as a receive array with four distinct sensitivity patterns and sensitivity comparable to that of a conventional 4-element loop receive array. The metaslab is much lighter than comparable dielectric pads and achieves all these benefits in a similar package as a conventional coil array.

View Presentation Video

Komlan Payne¹, Aditya A. Bhosale¹, Yunkun Zhao¹, and Xiaoliang Zhang^1
1Department of Biomedical Engineering, University at Buffalo, Buffalo, NY, United States

Keywords: Hybrid & Novel Systems Technology, RF Arrays & Systems

The study of skin diseases is by far among the difficult research in biomedical field. Nowadays, many techniques are available to perform skin examination. Magnetic Resonance Imaging (MRI), a non-invasive technique can provide detailed image of the skin. For such procedure, a whole-body coil can be used as the transmitter while receivers array coils are placed in close proximity of the region of interest. In this abstract we design an array of high impedance quadrature detectors with good decoupling performance for skin image at 7T.   

View Presentation Video

Maxim Terekhov¹, Ibrahim A. Elabyad¹, David Lohr¹, Anna Frey², Florian Schnitter², and Laura M. Schreiber^1
1Chair of Cellular and Molecular Imaging,Comprehensive Heart Failure Center, University Hospital Würzburg, Wuerzburg, Germany, ²Department of Internal Medicine I, Cardiology, University Hospital Würzburg, Wuerzburg, Germany

Keywords: RF Arrays & Systems, Parallel Transmit & Multiband, cardiovascular

The concept of the L-shaped loop elements architecture with the antisymmetric arrangement was applied to develop a 8Tx/32Rx transceiver array for cardiac MRI at 7T.  This work aimed to check B₁⁺ shimming and parallel imaging capabilities of the array and to perform the initial testing in human thorax phantom and pig cadaver. Both phase-only and pTX optimization modes demonstrated the possibility for efficient shaping of B1+  with an optimized spatial homogeneity. Despite the sub-optimal geometry of the pig thorax, the array demonstrated a good B1+ coverage of the heart region with no apparent destructive interferences.  

View Presentation Video

Jules Vliem^1,2, Raphael Tomi-Tricot^1,3,4, Irena Zivkovic², and Özlem Ipek^1,3
1Biomedical Engineering, Kings's College London, London, United Kingdom, ²Electrical Engineering, Technical University of Eindhoven, Eindhoven, Netherlands, ³London Collaborative Ultra high field System (LoCUS), King's College London, London, United Kingdom, ⁴MR Research Collaborations, Siemens Healthineers, Frimley, United Kingdom

Keywords: RF Arrays & Systems, High-Field MRI

In this work, we explored properties of various coaxial dipole designs and compared them with the conventional dipole. Dipoles were fabricated of RG58 coaxial cable and the total length was 34cm. S-parameters and flip angle maps of individual elements and array configurations were measured on a torso phantom. Comparison of flip angle maps shows very similar performances of all examined dipoles with the coaxial dipole being slightly advantageous. When placed in densely populated array configuration, coaxial dipoles were sufficiently decoupled and produced expected B1+ maps. Coaxial dipole shows promising performances to be used in a densely populated flexible torso array.  

View Presentation Video

Chunhu Song^1,2, Qiaoyan Chen^1,2, Shao Che^1,2,3, Haining Wang³, Xiaoliang Zhang⁴, and Ye Li^1,2
1Paul C. Lauterbur 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, ³Shanghai United Imaging Healthcare, Shanghai, China, ⁴Department of Biomedical Engineering, State University of New York at Buffalo, New York, NY, United States

Keywords: RF Arrays & Systems, RF Arrays & Systems

The ultra-flexible RF coil can fit the image subjects well and thus improve signal-to-noise ratio (SNR). In this study, four types of single-channel receiver coils using different materials with the same size were constructed. Phantom studies were performed on a 3T MRI system. As a result, the liquid metal coil can achieve a most similar performance as the conventional copper coil, while the liquid metal coil is more flexible. This demonstrates that the liquid metal coil has a good application potential in imaging curved anatomical structures.

View Presentation Video

Xiaoliang Zhang¹, Lance DelaBarre², Komlan Payne¹, Matt Waks², Gregor Adriany², and Kamil Ugurbil^2
1Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States, ²Radiology, University of Minnesota, Minneapolis, MN, United States

Keywords: RF Arrays & Systems, RF Arrays & Systems

In this work, a wrap-on 447MHz transceiver array using the 2^nd mode of coaxial transmission line resonator is designed, constructed and tested for human head imaging at the ultrahigh field of 10.5T. Results demonstrate the unique decoupling performance among the resonant elements achievable even for non-overlapped array layouts. The 10.5T images of a human head phantom acquired from the proposed array along with numerical simulations are shown.   

View Presentation Video

Wenjun Wang¹, Juan Diego Sánchez Heredia², Vitaliy Zhurbenko¹, and Jan Henrik Ardenkjær Larsen^2
1National Space Institute, Technical University of Denmark, Kongens Lyngby, Denmark, ²Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark

Keywords: RF Arrays & Systems, RF Arrays & Systems, matching

The noise figure of a matching network between a receive coil and a preamplifier with low input impedance can be estimated using relationship \(F\approx1+R_{11}/R_\mathrm{c}\). It is demonstrated how to use this relationship to choose optimal matching-decoupling network topology in terms of signal-to-noise ratio (SNR). The formula serves as an efficient tool to estimate noise figure of matching networks and is useful in low-field and high-coil-Q applications, where the noise of the matching network becomes comparable to coil noise.

View Presentation Video

Elizaveta Motovilova¹, Terry Ching², Jana Vincent³, Ek Tsoon Tan⁴, Victor Taracila³, Michinao Hashimoto², Fraser Robb³, Darryl Sneag⁴, and Simone Angela Winkler^1
1Departmetn of Radiology, Weill Cornell Medicine, New York, NY, United States, ²Engineering Product Development Pillar, Singapore University of Technology and Design, Singapore, Singapore, ³GE Healthcare, Aurora, OH, United States, ⁴Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY, United States

Keywords: RF Arrays & Systems, RF Arrays & Systems, Liquid metal, Stretchable RF coils

Stretchable receive coils can provide conformal fitting, improved SNR, and dynamic imaging capabilities. However, conductor stretching alters the resonance frequency, reducing potential SNR advantages. Previously, we proposed and demonstrated in a single element prototype a smart self-tuning coil design which allows to maintain the desired Larmor frequency with stretching. This work investigates the applicability of self-tuning techniques in a multi-channel stretchable coil array and demonstrates its performance in silico and in vitro. Simulation results show stable resonance frequency (<1%) and sensitivity (±5%) for varied load/stretching conditions. In vitro imaging demonstrates consistent performance of individual coil elements and the array (SNR=146).

View Presentation Video

Karthik Lakshmanan^1,2, Alena Schelokova³, Stanislav Glybovski³, Mary Bruno¹, and Christopher Collins^1,2
1Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, NYU Grossman School of Medicine, New york, NY, United States, ²Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, NYU Grossman School of Medicine, New york, NY, United States, ³ITMO University, St. Petersburg, Russian Federation

Keywords: Non-Array RF Coils, Antennas & Waveguides, RF Arrays & Systems

Quantitative evaluation of transmit efficiency and receive-specific SNR were performed for two different metasurfaces in a body-sized phantom for cases with 1) excitation and reception using the system body coil and 2) excitation with the system body coil and reception with a commercial 12-element array. Similar evaluations were performed for one of the metasurfaces in vivo with the receive array present, and for comparisons all measurements were also made with no metasurface present. Both metasurfaces were seen to significantly improve transmit efficiency in all cases, and to improve SNR when the body coil was used for reception, with effects being strong near the metasurface and extending toward the center of the phantom. The metasurfaces had minimal effects on receive SNR of the commercial Rx array.

View Presentation Video

Xin Li¹, Hannes M. Wiesner¹, Xiao-Hong Zhu¹, and Wei Chen^1
1Department of Radiology, University of Minnesota, Minneapolis, MN, United States

Keywords: Non-Array RF Coils, Antennas & Waveguides, RF Arrays & Systems

It has been demonstrated that integrating ultra-High Dielectric Constant  (uHDC) materials with a RF coil can achieve large improvement in RF magnetic field (B₁) and imaging sensitivity. A typical configuration inserts the uHDC materials between the imaging object and the RF coil, resulting in a weak B₁ from the coil due to the distance from the object. In this study, we explored different configuration options and found that the best arrangement was to place the uHDC materials outside the coil, leaving no gap between the RF coil and the object, for optimal imaging applications.

View Presentation Video

Sergio Solis-Najera¹, Jelena Lazovic², Fabian Vazquez¹, and Alfredo Odon Rodriguez^3
1Departamento de Fisica, UNAM, Mexico City, Mexico, ²Department of Physical Intelligence, Max Planck Institute for Intelligent Systems, Stuttgart, Germany, ³Electrical Engineering, UAM Iztapalapa, Mexico City, Mexico

Keywords: Non-Array RF Coils, Antennas & Waveguides, RF Arrays & Systems, travelling-wave

We propose a method to remotely acquire MR images at 7 T with a preclinical imager using a bio-inspired surface coil, a parallel-plate waveguide and a non-selective metamaterial. Phantom images were acquired with and without a flexible metasurface inserted in cylindrical phantom filled with saline solution and a birdcage coil. Uniformity profiles were computed for all cases showing that the birdcage coil and metasurface profiles have a very good correspondance. An improvement was observed for the images obtained with the metasurface. This approach offers a convenient alternative to obtained high quality images.

View Presentation Video

Yunkun Zhao¹, Komlan Payne¹, Leslie YIng¹, and Xiaoliang Zhang^1
1Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States

Keywords: New Devices, Spinal Cord

This study proposes a coupled planar radio frequency (RF) array for spine imaging at 7T. Multiple identical loop coils are closely placed to achieve strong EM coupling in order to form a multimodal resonator. This coupled resonator can design large high-frequency RF coils for ultrahigh field imaging applications in humans.

View Presentation Video

Manisha Shrestha¹, Mirsad Mahmutovic¹, Sam-Luca JD Hansen¹, Jason P Stockmann², and Boris Keil^1
1Institute of Medical Physics and Radiation Protection, TH Mittelhessen University of Applied Sciences, Giessen, Germany, ²A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States

Keywords: RF Arrays & Systems, High-Field MRI, detuning

Active detuning of receive array coil during transmit prevents large currents being induced in the coil which could damage sensitive electronic components and create SAR hotspots. The standard method of adjusting active detuning using a double probe shows an offset in the resonant frequency set at bench when tested in the presence of a scanner. Setting a high impedance at the input of loop using S11 measurement exactly at Larmor frequency has proven to be a better method to detune loops actively.  

 

View Presentation Video

KOMLAN PAYNE¹, Aditya Ashok Bhosale¹, Leslie Lei Ying¹, and Xiaoliang Zhang^1
1Department of Biomedical Engineering, University at Buffalo, Buffalo, NY, United States

Keywords: Parallel Imaging, Multimodal, Dual nuclear

In this work, we developed a decoupled multichannel double-tuned RF coil array for ¹H/³¹P MR imaging and spectroscopy at the ultrahigh field of 7T. One of the difficulties in designing such high-frequency double-tuned coil arrays is to electromagnetically decouple the two frequency channels simultaneously. To address this issue, we designed a double-crossed magnetic wall (or ICE) decoupling which can independently and simultaneously decouple the ¹H channels and ³¹P channels. With the improved performance, this developed ¹H/³¹P transceiver array is expected to offer improved detection quality and imaging speed in ¹H/³¹P metabolic imaging applications at 7T.

View Presentation Video

Alireza Sadeghi-Tarakameh¹, Matt Waks¹, Andrea Grant¹, Jeromy Thotland¹, Russell L Lagore¹, Lance DelaBarre¹, Edward Auerbach¹, Pierre‐Francois Van de Moortele¹, Gregor Adriany¹, Kamil Ugurbil¹, and Yigitcan Eryaman^1
1Center for Magnetic Resonance Research (CMRR), University of Minnesota, Minneapolis, MN, United States

Keywords: RF Arrays & Systems, High-Field MRI

Higher signal-to-noise ratio (SNR) is the primary maxim for increasing the magnetic field strength of MRI scanners. However, RF coils comprised of loops do not capture the highest achievable SNR that is theoretically available at ultrahigh field (defined as ≥7T) MRI. In this study, we investigate the hypothesis of increasing central head SNR at 10.5T by combining loop and dipole receiver elements. For this purpose, we manufactured a 32-channel hybrid RF coil comprised of 25 receive-only loops and 7 transceiver NODES dipoles. This 32ch hybrid coil achieved ~80% higher central SNR compared to a 32ch loop array.