| 15:45 | 0670.
 | Development of a Compact Head-only Scanner with a Window and Shoulders Outside its Vertical Bore. Taylor Froelich1, Sebastian Theilenberg2, Joseph Bailey3, Lance DelaBarre1, Steve Suddarth1, Daniel Cosmo Pizetta4, Mateus José Martins4, Edson Luiz Géa Vidoto4, Yun Shang2, Russell Lagore1, Terence W Nixon5, John P Strupp1, Jamal Olatunji3, Mathieu Szmigiel6, Mark Hunter7, Edgar Rodríguez Ramírez8, Mailin Lemke9, Chathura Kumaragamage5, Huub Weijers3, R Gilberto Gonzalez10, J. Thomas Vaughan2,11, Robin A. de Graaf5, Christoph Juchem2,11, Alberto Tannús4, Ben Parkinson3, and Michael Garwood1,12
1Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States, 2Department of Biomedical Engineering, Columbia University, New York, NY, United States, 3Robinson Research Institute, Victoria University of Wellington, Wellington, New Zealand, 4Centro de Imagens e Espectroscopia por Ressonância Magnética - CIERMag - São Carlos Physics Institute, University of São Paulo – IFSC-USP, São Carlos, Brazil, 5Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, United States, 6Air Liquide, Paris, France, 7Tranzpower Limited, Wellington, New Zealand, 8Victoria University of Wellington, Wellington, New Zealand, 9Dreiform GmbH, Hürth, Germany, 10Division of Neuroradiology, Massachusetts General Hospital, Boston, MA, United States, 11Department of Radiology, Columbia University Medical Center, New York, NY, United States, 12Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States Keywords: Hybrid & Novel Systems Technology, Hybrid & Novel Systems Technology, New Devices, Gradients, Magnets, Head-Only Motivation: MRI has evolved into an indispensable tool, but remains inaccessible to much of the world’s population. Goal(s): To build a compact, low-cost, mid- to high-field MRI system capable of producing diagnostic-quality images. Approach: A complete redesign of MR scanner architecture and key technologies; including a compact high temperature superconducting magnet, multi-coil gradient array, and digital spectrometer. The system required extensive testing prior to integration and initial imaging. Results: Initial experiments produced high-resolution images despite using an extremely inhomogeneous magnetic field from the compact 0.7 tesla magnet. Impact: This work represents a significant milestone within the MRI community to address the problems in accessibility and under-utilization facing MRI today. By focusing on ways to develop portable, low-cost systems, the accessibility of this imaging modality can increase substantially. |
| 15:57 | 0671.
 | A Universal Bz Coil for Uniform Multiphoton Excitation in High-Field MRI John M Drago1,2,3, Mathias Davids2,3, Jason P Stockmann2,3, Bastien Guerin2,3, and Lawrence L Wald2,3,4
1Dept. of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States, 2Harvard Medical School, Boston, MA, United States, 3Dept. of Radiology, Massachusetts General Hospital, A. A. Martinos Center for Biomedical Imaging, Boston, MA, United States, 4Dept. of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States Keywords: RF Pulse Design & Fields, Brain Motivation: Contrast in high-field MRI is obscured by the spatially non-uniform excitation flip angle profile of conventional birdcage transmit coils. Goal(s): We demonstrate that a single $$$B_z$$$ coil operated in the kHz range can supplement a birdcage to create a spatially-uniform flip angle profile using multiphoton excitation. Approach: We use a stream function boundary element method to optimize the $$$B_z$$$ coil windings to produce homogeneous nonselective multiphoton excitations across a universal pulse database and validate with Bloch simulations. Results: The single $$$B_z$$$ channel achieved a mean flip angle NRMSE of 13.9% for a 90º target MP-pTx pulse in test subjects. Impact: The design method provides a simplified hardware configuration and reduced local SAR concerns compared to either conventional pTx or our previous work using a full shim array in conjunction with multiphoton parallel transmission. |
| 16:09 | 0672.
 | Multinuclear MRI Using a Single Adaptable Transmit Hardware Natalia Gudino1
1MRIEngT, LFMI,NINDS, NIH, Bethesda, MD, United States Keywords: Hybrid & Novel Systems Technology, New Devices Motivation: Routine studies of nuclei other than 1H are constrained by the need of separate fixed tuned hardware. Goal(s): To increase flexibility of the multinuclear setup by developing an adaptable single transmit hardware to allow excitation of many low-frequency nuclei and 1H. Approach: The conventional remote broadband amplifier was replaced by an optically controlled dual-tuned on-coil amplifier for 1H and X-nuclei excitation. The amplifier can be automatically tuned to the selected frequency by pulse-width-modulation of an optically transmitted pulse. Results: Automatic tuning of a first prototype was possible for excitation of 13C, 23Na and 129Xe, while performance of 1H excitation at 7T was unaffected. Impact: The presented technology combined with new adaptable receive hardware can advance the implementation of routine multinuclear studies to extend research of X-nuclei and their potential clinical use. |
| 16:21 | 0673.
 | Dynamic tracking of cardiac motion fields using multi-frequency scattering parameters of an RF array – an MRI based feasibility study Bart Romke Steensma1,2 and Cornelis Antonius Theodorus van den Berg1,2
1Computational Imaging Group, UMC Utrecht, Utrecht, Netherlands, 2PrecorDx, Utrecht, Netherlands Keywords: New Devices, Cardiovascular Motivation: To enable high frame rate spatial mapping of cardiac mechanical motion with an array of RF antennas. Goal(s): Investigate the feasibility of estimating 2D motion fields based on measurements of wideband multi-channel RF scattering parameters. Approach: Paired CINE MRI and multi-channel wideband (55-1300 MHz) RF scattering measurements were acquired in vivo. Motion fields were determined from MRI, a Gaussian process regression model was trained and tested to predict motion fields from the RF scattering parameters. Results: 2D motion fields in a 4Ch CINE image of the heart can be reconstructed with high precision (RMS error 0.66mm) based on RF scattering measurements. Impact: We demonstrated feasibility
of high precision and high framerate spatial motion mapping with RF antennas.
Further validation with real-time MRI is warranted. This method could be
applicable for motion tracking during medical imaging or in a low complexity
care setting. |
| 16:33 | 0674.
 | Moving MRI (mMRI): imaging a moving body with synchronized magnet movement Jingting Yao1,2, Artan Kaso1,2, Nikhil Patel3, Yin-Ching Iris Chen1,2, Yi-Fen Yen1,2, André J.W. van der Kouwe1,2, Daniel M. Merfeld4, and Jerome L. Ackerman1,2
1Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 2Harvard Medical School, Boston, MA, United States, 3Radiology, Massachusetts General Hospital, Boston, MA, United States, 4The Ohio State University College of Medicine, Columbus, OH, United States Keywords: Hybrid & Novel Systems Technology, Hybrid & Novel Systems Technology, Artifacts, Brain, Motion Correction Motivation: MRI is largely limited to scenarios involving small-scale bodily movements to minimize artifacts and field-induced physiological effects. Goal(s): We are developing a moving MRI system where the magnet and subject’s head remain stationary with respect to each other during large-scale motion. Approach: Utilizing a compact, dry 1.5T magnet, we built an apparatus that tilted the entire magnet assembly, including the cold head, gradient/shim/RF coils, and the subject, up and down during scanning. Results: We demonstrated the ability to scan phantoms and live animals while the magnet is in motion and to correct for imaging artifacts caused by tilting the magnet. Impact: Our proof-of-concept prototype moving MRI
system supports the future viability of developing a human-scale moving MRI
system, which has the potential to advance studies in vestibular research,
traumatic brain injury, and brain-behavior interactions, among other areas. |
| 16:45 | 0675.
 | Low-frequency magnetic signal detection using stimulus-induced rotary saturation sequence in ultra-low field MRI Takenori Oida1, Takahiro Moriya1, Akinori Saito1, Hiroyuki Ueda2, Yosuke Ito2, and Motohiro Suyama1
1Hamamatsu Photonics K.K., Hamamatsu, Japan, 2Kyoto University, Kyoto, Japan Keywords: Low-Field MRI, Low-Field MRI Motivation: Realization of biomagnetic measurement using MRI with high spatial resolution. Goal(s): Detection of low-frequency magnetic signals below 50 Hz in ultra-low field MRI (ULF-MRI). Approach: Magnetic signal detections were performed by stimulus-induced rotary saturation (SIRS) sequence in ULF-MRI. As magnetic signals, reference magnetic fields with 225 nTpp in amplitude and 10, 15, ..., 70 Hz in frequency were applied to the bottle phantom. Results: The signal reduction of approximately 20% were observed when the reference magnetic field between 30 Hz and 45 Hz were applied. This indicates that low-frequency magnetic signals can be detected by the SIRS sequence in ULF-MRI. Impact: We demonstrate the feasibility of biomagnetic measurement below 50 Hz such
as brain activity first time by realizing low-frequency magnetic signal
detection using stimulus-induced rotary saturation sequence in ULF-MRI with 7
mT in B0. |
| 16:57 | 0676.
 | A 16-Ch Elastic Thin RF Coil Array for Whole Brain Concurrent TMS-fMRI Yunsuo Duan1,2, Feng Liu1,2, Rachel Marsh1,2, Matthew Riddle1,2, Gauraw H. Patel1,2, Lawrence S. Kegeles1,2, John Thomas Vaughan3, and Jack Grinband1,2
1MR Research, Department of Psychiatry, Columbia University, New York, NY, United States, 2New York State Psychiatric Institute, New York, NY, United States, 3Columbia MR Research Center, Columbia University, New York, NY, United States Keywords: RF Arrays & Systems, RF Arrays & Systems, TMS Motivation: The low TMS efficiency and complexity of the setup for whole brain concurrent TMS-fMRI remain challenging due to the lack of feasible RF coil arrays. Goal(s): We proposed a 16-channel elastic whole brain RF coil array to increase the TMS efficiency and flexibility. Approach: We developed a highly flexible close-fitting coil former with 3D printing and evenly placed the 16 coil loops made of flexible shielding sleeves on the former. Results: The measured TMS efficiency was about 80% at the inner wall of the coil array. The SNRs of experimental images were comparable with those acquired using Nova 32-ch coil array. Impact: The proposed 16-ch elastic coil array was capable of significantly improving the TMS efficiency and simplifying the setup of whole brain concurrent TMS-fMRI. |
| 17:09 | 0677.
 | Four-Channel MM-Wave Radar Testbed for Neck vs Chest Cardiac Sensing Lauren Hughes1, Fraser Robb2, Shreyas Vasanawala3, John Pauly1, and Greig Cameron Scott1
1Electrical Engineering, Stanford University, Stanford, CA, United States, 2GE Healthcare, Aurora, OH, United States, 3Radiology, Stanford University, Stanford, CA, United States Keywords: Hybrid & Novel Systems Technology, Hybrid & Novel Systems Technology, Radar Motivation: Respiratory and cardiac gating are common in modern MRI, but require additional sensors in contact with the patient and the associated cabling. Goal(s): Our goal is to determine if CW mm-wave radar can act as a robust non-contact cardiac and respiratory sensor, with potential for gating in MRI. Approach: A 4-channel 24 GHz radar test bed is developed with a pair of neck radars and a pair of chest radars. SSA and ICA methods help extract waveform structure relative to an ECG. Results: The CW radars nicely separate breathing and heart rate with distinct features at the ECG QRS complex. Impact: MM-wave radar could provide a non-contact sensor of cardiac/breathing in MRI. Potential applications include non-contact gating, and independent vascular pulse or motion sensing for use in neuroimaging. |
| 17:21 | 0678.
 | Ultrahigh Resolution Imaging of Zebrafish Embryos with a µMRI Insert in a Horizontal Bore Small Animal Scanner Thomas Hüfken1, Tobias Lobmeyer1, Bernd Gahr1, and Volker Rasche1
1Ulm University, Ulm, Germany Keywords: New Devices, New Devices Motivation: The absence of hardware specifically tailored for horizontal bore small animal MRI systems hinders the achievement of ultrahigh-resolution imaging. Goal(s): To facilitate volumetric imaging at sub 10³ µm³ spatial resolutions in a conventional horizontal small animal scanner. Approach: A custom-made high-performance gradient system and RF-hardware was interfaced to the system RF- and gradient-amplifiers, avoiding the requirement for specialized imaging software. A constant time imaging sequence was employed to capture ultrahigh-resolution images. Results: The setup was successfully tested for imaging of zebrafish embryos at different time points post fertilization with an isotropic spatial resolution of 9³ µm³. Impact: The suggested approach enables isotropic single-digit
µm ultrahigh resolution imaging in conventional horizontal bore MRI systems. This
supports novel imaging applications for a wide range of tiny animals, plants,
or biological tissue without dedicated microscopy MR systems. |
| 17:33 | 0679.
 | Imaging pressure gradients and stress fields driving ISF flow in the brain by assimilating DENSE pulsatile motion data into a poroelastic model. Matthew Mcgarry1, Jaco Zwanenburg2, John Weaver3, and Keith Paulsen1
1Dartmouth College, Hanover, NH, United States, 2University Medical Center Utrecht, Utrecht, Netherlands, 3Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States Keywords: Neurofluids, Neurofluids Motivation: Interstitial fluid (ISF) flow in the brain is important for brain function and therapies. Very slow ISF flow is difficult to directly measure, however, the driving forces can be estimated from pulsatile motion fields. Goal(s): We assimilate pulsatile motions from DENSE sequences into a poroelastic computational model which allows fluid pressure gradient and solid stress fields to be extracted. Approach: Generalized least squares and Galerkin weighted residual methods were used to fit a pulsatile blood pressure field to the data and compute stresses/pressure gradients. Results: Stress and pressure images show good symmetry and distributions are as expected from anatomical considerations. Impact: Imaging
the pulsatile fluid pressure gradients and solid stress fields provides new
insights into the forces which drive flow of interstitial fluid in the brain, which is of
critical importance in Alzheimer’s disease and currently very difficult to
directly measure. |