Chang-Hoon Choi¹, Airat Galiamov¹, Suk-Min Hong¹, Jörg Felder¹, Wieland A. Worthoff¹, and N. Jon Shah^1,2,3,4
1INM-4, Forschungszentrum Juelich, Juelich, Germany, ²INM-11, Forschungszentrum Juelich, Juelich, Germany, ³JARA-BRAIN-Translational Medicine, Aachen, Germany, ⁴Department of Neurology, RWTH Aachen University, Aachen, Germany

X-nuclei MR offers unique access to important metabolic information in tissues. Multi-tuned coils are required for the X-nuclei measurements, but designing a well-performing coil is challenging. In this study, we present our novel design and performance evaluation of an interchangeable, twin, double-tuned, head coil array for ¹H/²³Na MR imaging and ¹H/³¹P MR spectroscopy at 7 T. The outer proton array was built using an alternatingly positioned 4-channel dipole antenna and a 4-channel microstrip transmission line array to improve decoupling. The inner 8-channel X-nuclei loop arrays, orthogonal to the ¹H, were designed identically to enable conventionally switching between ²³Na and ³¹P.   

Nikolai Avdievich¹, Georgiy Solomakha², Loreen Ruhm¹, Anke Henning^1,3, and Klaus Scheffler^1,4
1Max Planck Institute for Bilogical Cybernetics, Tuebingen, Germany, ²Nanophotonics and Metamaterials, ITMO University, St. Petersburg, Russian Federation, ³Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, ⁴Department for Biomedical Magnetic Resonance, University of Tübingen, Tuebingen, Germany

Dipole antennas have been successfully utilized at ultra-high fields (UHF, >7 T) as elements of human body arrays. Usage of dipoles for UHF human head arrays is still under development. In this case, dipoles must be made much shorter, and placed at a relatively large distance to the head. As a result, dipoles are not well loaded and are often purely decoupled. In this work, we developed a novel method of decoupling of adjacent dipole antennas, and used this technique while constructing a novel 9.4 T human head TxRx dipole array coil. The array demonstrates good decoupling and full-brain coverage.

Jonathan Cuthbertson^1,2, Trong-Kha Truong^1,2, Vani Yadav^1,2, Fraser Robb³, Allen Song^1,2, and Dean Darnell^1,2
1Brain Imaging and Analysis Center, Duke University, Durham, NC, United States, ²Medical Physics Graduate Program, Duke University, Durham, NC, United States, ³GE Healthcare Inc., Aurora, OH, United States

The integrated RF/wireless coil design enables MRI imaging and wireless data transfer with the same coil thereby reducing the number of wired connections in the scanner. Here, we implement this design onto a 48-channel head coil array to enable two independent wireless data streams for two separate applications, specifically, wireless 1) control of the DC currents used for B₀ shimming and 2) respiratory tracking with a respiratory belt. In vivo experiments in the brain showed that this coil array significantly reduced B₀ inhomogeneities (-41%) and EPI distortions while simultaneously streaming respiratory data from the subject without data loss.

Chris Vassos¹, Fraser Robb², Shreyas Vasanawala³, John Pauly¹, and Greig Scott^1
1Electrical Engineering, Stanford University, Stanford, CA, United States, ²GE Healthcare, Aurora, OH, United States, ³Radiology, Stanford University, Stanford, CA, United States

A Silicon Germanium alternative to standard HEMT pre-amplifiers is proposed. This is intended to ameliorate the high power consumption associated with current implementations for the wireless use case in which power is a limiting factor. The proposed pre-amp is evaluated for linearity and gain through a behavioral model that is extracted from SPICE simulation to process k-space data. It is found that the non-linearities introduced by the SiGe device begin to have an impact on image quality in high dynamic range cases. This encourages further investigation into SiGe devices as low-power preamplifiers.

Guang Yang¹, Sergei Obruchkov², and Robin Dykstra^1
1School of Engineering and Computer Science, Victoria University of Wellington, Wellington, New Zealand, ²Robinson Research Institute, Victoria University of Wellington, Wellington, New Zealand

This abstracts describes the development of a complete multi-channel MRI console that can be the basis for many MR projects. To support the growing open-source hardware MR community we are making  a collection of PXIe modules and IP available to anyone to use and develop applications on. A System Controller Board, a 2-channel Tx and 4-channel Rx transceiver board, an FMC General Purpose Module, PXIe data transfer engine IP, Linux API and device drivers can be accessed online https://github.com/mr-kit/.

Andrew Dupuis¹, Dominique Franson¹, Nicole Seiberlich², and Mark A Griswold^1,3
1Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, ²Radiology, University of Michigan, Ann Arbor, MI, United States, ³Department of Radiology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States

Clinical MRI scanners are not designed to allow for easy communication with 3rd party devices, whether for development or clinical purposes. However, most modern scanners provide a synchronization trigger interface that is sequence (and therefore research-user) controllable. We investigated using the synchronization trigger as a serial data output for arbitrary data, and successfully implemented a 192 kilobaud simplex serial interface that can be implemented within any sequence to enable arbitrary data transfer to and control of any external UART device. This opens significant opportunities for 3rd party hardware and software research without manufacturer consent or firmware changes. 

Clarissa Zimmerman Cooley^1,2, Patrick C McDaniel^1,3, Jason P Stockmann^1,2, Farrah J Mateen^2,4, and Lawrence L Wald^1,2,5
1Athinoula A Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, ²Harvard Medical School, Boston, MA, United States, ³Dept. of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, ⁴Dept. of Neurology, Massachusetts General Hospital, Boston, MA, United States, ⁵Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States

Lumbar Punctures (LP) are generally guided by palpation only without visualization of the internal anatomy, leading to repeat attempts and/or avoidance in difficult cases. Image guidance with US and X-ray is possible, but US has poor depth and CSF contrast and radiation from X-ray complicates Point of Care (POC) use.  We present a magnet design for a POC MR guided LP device that will couple to a mechanical track for needle insertion. The single-sided magnet is an NdFeB array and achieves a 40mT field and ~50mT/m built-in gradient in the ROI. Simulations of the magnet and imaging procedure are presented.

Ehud J Schmidt^1,2, Yue Chen³, Anthony Gunderman³, Junichi Tokuda⁴, Hassan Elahi⁵, Ravi T Seethamraju⁶, Henry R Halperin⁵, and Akila N Viswanathan^2
1Medicine (Cardiology), The Johns Hopkins University, Baltimore, MD, United States, ²Radiation Oncology, Johns Hopkins University, Baltimore, MD, United States, ³Mechanical Engineering, University of Arkansas, Fayetteville, AR, United States, ⁴Radiology, Brigham and Womens Hospital, Boston, MA, United States, ⁵Medicine (Cardiology), Johns Hopkins University, Baltimore, MD, United States, ⁶MRI, Siemens Healthineers, Boston, MA, United States

Evaluating tissue properties prior-to or during therapy, such as locating cancerous and necrotic cells, or characterizing response to radiation or ablation, is conventionally performed by tissue excision, followed by pathologic examination. An alternative is diagnosing tissue in-situ without removing it, as performed using Optical-Coherence-Tomography or Intra-Vascular-UltraSound. We aim to perform tissue definition in soft-tissues not accessed through body-orifices or blood-vessels by combining; (1) Steerable tissue-puncture, (2) MR-Tracking-motion-localization, and (3) imaging along the punctured-holes' walls. Utilization requires rapid high-CNR multiple-contrast MRI.  A deflectable virtual-biopsy “gun” for diagnosing cervical-cancer radiation-therapy response was developed. It imaged ~15mm surrounding punctured-holes created for brachytherapy seed-delivery.    

J. Rock Hadley¹, Henrik Odeen², Robb Merrill², Sam Adams², Viola Rieke², Allison Payne², and Dennis Parker^2
1Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, United States, ²University of Utah, Salt Lake City, UT, United States

This work uses an RF screen, placed over the top of a human skull phantom, to reduce image banding artifacts that are common in transcranial transducer MRI.  The goals of the study are to improve imaging homogeneity over the region of the brain by changing RF field patterns that cause the artifacts, and to find a solution that doesn’t attenuate or distort the ultrasound properties of the transducer.  Hydrophone and focused ultrasound heating studies are performed to measure ultrasound screen transparency and MRI studies are performed to evaluate the effects the screen has on homogeneity and artifact reduction.  

Sai Abitha Srinivas¹, Clarissa Z Cooley^1,2, Jason P Stockmann^1,2, Patrick C McDaniel^1,3, and Lawrence L Wald^1,2,4
1Athinoula A Martinos Center for Biomedical Imaging, Charlestown, MA, United States, ²Harvard Medical School, Boston, MA, United States, ³Dept. of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, ⁴Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States

The performance of a low field Point of Care (POC) MRI system operating outside an RF shielded room is adversely affected by the presence of electromagnetic interference signals, which produce image artifacts, sometimes complicated enough to be confused with image noise. We demonstrate a post-processing interference suppression technique using an external reference coil and dynamically updated transfer function to detect the interference and remove it from the imaging data.