View Presentation Video

Bilguun Nurzed¹, Dennis Hieronymi¹, Thomas Wilhelm Eigentler¹, and Thoralf Niendorf^1,2,3
1Max-Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany, ²Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany, ³MRI.TOOLS, Berlin, Germany

Keywords: RF Arrays & Systems, Bioeffects & Magnetic Fields

Investigation of the power correlation matrix at 21.0 T is vital to elucidate the electrodynamics for human body and cardiac MR as well as the RF antenna performance. Recognizing this opportunity, this abstract assesses the power losses for multi-channel RF transceiver arrays for human body and cardiac MR using 32-channel pTx/Rx self-grounded bow-tie building block (SGBT). Losses were determined inside the tissue, lossy material of the antenna, lumped elements of the tuning and matching network and due to coupling and radiation.

View Presentation Video

Daniel Löwen¹, Eberhard Daniel Pracht¹, Vincent Gras², Aurelien Massire³, Franck Mauconduit², Nicolas Boulant², and Tony Stöcker^1,4
1German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, ²Université Paris-Saclay, Commissariat à l’Energie Atomique, CNRS, NeuroSpin, BAOBAB, Gif sur Yvette, France, ³Siemens Healthineers, Saint-Denis, France, ⁴Department of Physics and Astronomy, University of Bonn, Bonn, Germany

Keywords: High-Field MRI, RF Pulse Design & Fields, Brain, Parallel Transmit & Multiband

Multi-Slice T2-weighted MR imaging is a fundamental technique in brain imaging but suffers from field inhomogeneities at ultra-high field systems. In this work we present a pulse design method which provides slab-selective universal pulses with phase-coherent excitation profiles over selected brain regions. Applied in a 3D variable flip angle turbo-spin-echo (TSE) sequence, the pulses achieve superior SNR compared to multi-slice TSE imaging and B1+ field inhomogeneity mitigation.

 

View Presentation Video

Marco L. Wittrich^1,2, Armin M. Nagel^1,3, Sebastian Schmitter^1,4, Peter Bachert^1,2, Mark E. Ladd^1,2,5, and Fabian J. Kratzer^1,2
1Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, ²Faculty of Physics and Astronomy, University of Heidelberg, Heidelberg, Germany, ³University Hospital Erlangen, Institute for Radiology, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU), Erlangen, Germany, ⁴Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany, ⁵Faculty of Medicine, University of Heidelberg, Heidelberg, Germany

Keywords: High-Field MRI, Non-Proton, 23Na,SMS,radial CAIPIRINHA

 In this work, a simultaneous multi-slice (SMS) approach using radial CAIPIRINHA was implemented for sodium MRI. Initial experiments were confined to two simultaneously excited slices. Here, simulated and measured slice profiles agreed well with expectations. Further, the SNR of the acquired SMS images was analyzed and compared to reference measurements of the individual slices. An SNR increase of up to 38% when maintaining flip angle and up to 13% for constant SAR was observed. Lastly, in-vivo head images (2.9x2.9x12mm³) were obtained showing the feasibility of ²³Na SMS MRI.

View Presentation Video

Hecheng Jin¹, Andrea N Sajewski¹, Tales Santini¹, Tiago Martins¹, Jacob P Berardinelli¹, Anthony DeFranco¹, Howard J Aizenstein¹, and Tamer S Ibrahim^1
1University of Pittsburgh, Pittsburgh, PA, United States

Keywords: High-Field MRI, Simulations, Head position, B1+ field, 7T MRI

In this work, we computationally and experimentally evaluated the B₁⁺ field and SAR generated by a 60-channel Tic-Tac-Toc RF coil at 7T MRI scanner on a variety of participants, head models and head positions. On three anatomically detailed human head models, we found slight changes in the intensity and the distribution of B₁⁺ field and SAR over the whole brain when the head was moved out from the top of the coil. This was confirmed in both simulation and experimental B₁⁺ maps. Our results highlighted the impact of imaging setup on imaging quality.

View Presentation Video

Aditya Ashok Bhosale ¹, Leslie Ying¹, and Xiaoliang Zhang^1
1Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, United States

Keywords: High-Field MRI, RF Arrays & Systems

To determine the optimal number of channels employed in an array system for Human Head imaging at 7T, we examined different multi-channel circular LC loop array systems, ranging from 4-channel to 64-channel arrays.

View Presentation Video

Alexis Amadon^1,2,3, Vincent Gras^1,2,3, Edouard Chazel^1,2,3, Paul-François Gapais^1,2,3, Franck Mauconduit^1,2,3, Alexandre Vignaud^1,2,3, Nicolas Boulant^1,2,3, and Michel Luong^2,4
1NeuroSpin, CEA, Gif-sur-Yvette, France, ²Paris-Saclay University, Gif-sur-Yvette, France, ³Baobab, CNRS, Gif-sur-Yvette, France, ⁴IRFU, CEA, Gif-sur-Yvette, France

Keywords: High-Field MRI, High-Field MRI, 11.7T, Signal-to-Noise Ratio

The Iseult coil, developed for MRI of the human brain at 11.7T, was presented at last year’s ISMRM meeting. Here we show SNR phantom measurements in comparison with the Avanti2 coil, a replica of the Iseult coil tuned at 300 MHz (for 7T). We derive a new power dependence of the SNR vs B0.

View Presentation Video

Seyedeh Nasim Adnani^1,2, Sultan Zaman Mahmud^1,2, Thomas S. Denney^1,2, and Adil Bashir^1,2
1Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, United States, ²Auburn University MRI Research Center, Auburn University, Auburn, AL, United States

Keywords: High-Field MRI, Spinal Cord, T2* mapping, Artifacts

Ultra-high-field (UHF) Spinal Cord (SC) imaging could be helpful in detecting subtle pathological changes in the human SC. The increased effect of magnetic field inhomogeneity at UHF on T2* renders the quantification unreliable. Therefore, the field correction methods are critical. We have demonstrated the application of the Voxel Spread function method, to address this issue in human SC at 7T. F-term correction was applied to the pre-processed SC images, and the T2* values were reported for SC GM and WM both before and after field inhomogeneity correction. VSF reduces magnetic field inhomogeneity effects for quantitative T2* mapping in human SC. 

View Presentation Video

Jinghang Li¹, Eduardo Diniz², Taylor Forry³, Tamer Ibrahim^1,4, Howard Aizenstein^1,4, and Minjie Wu^4
1Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States, ²Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, PA, United States, ³Temple University, Philadelphia, PA, United States, ⁴Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States

Keywords: High-Field MRI, Machine Learning/Artificial Intelligence

In this work, we explored the domain adaptation problem in deep learning segmentation. Specifically, we applied the residual U-net [1] on 3T and 7T Fluid Attenuated Inverse Recovery (FLAIR) images to delineate the white matter hyperintensity (WMH) in a 2D fashion. We leveraged learning without forgetting [2] to regulate the network’s learning in the new domain to preserve the model’s performance on the old domain while still achieving satisfying results on the new domain images.

View Presentation Video

Minfeng Xu¹, Steve Buresh¹, Anbo Wu¹, Shike Huang¹, and Thomas Foo^1
1Global Research, General Electric, Niskayuna, NY, United States

Keywords: High-Field MRI, Magnets (B0), Superconducting Magnet; 16 T

An electromagnetic design of a 16.0 T MRI magnet using a combination of Nb3Sn and NbTi superconductors has been completed. It consists of a 9.0 T inner Nb3Sn solenoid and a set of outer NbTi coils that produces 7.0 T field, for a combined 16.0 T field. The design revealed very high hoop tensile and axial compressional stresses in the Nb3Sn coil. Alloy-reinforced high-strength Nb3Sn wires were selected for use in this project. For a magnet to operate in a persistent mode, superconducting joints between Nb3Sn wire segments need to be developed. Various joint configurations were attempted with some success.

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: High-Field MRI, Multimodal

Recently, intensive research has been conducted on coaxial‐transmission‐line (CTL) RF coils for nuclear magnetic resonance (NMR) at frequency ranging from high field to ultra-high field. The flexibility of CTL is to some extent required to image dynamic anatomy of the human body. Analysis on the CTL coils based on transmission line theory has revealed multimode operating frequency. Consequently, CTL coils can be useful to implement dual-nuclear RF coil resonator designed for Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS). In this abstract, we design a dual-band CTL with independent tuning capabilities.   

View Presentation Video

Celik Boga¹ and Anke Henning^1
1UT Southwestern Medical Center, Dallas, TX, United States

Keywords: High-Field MRI, RF Pulse Design & Fields

The T₂*contrast specifically benefits from 7T human MRI systems and is frequently used in Neuroimaging. However, B₁⁺ and B₀ inhomogeneity at 7T limits the effectiveness of the T₂*. A method originally proposed to minimize channel effects in the field of telecommunications, was adopted to a dual channel parallel transmission (pTx) human 7T MRI system. Final images are obtained by the unique combination of four small angle GRE acquisitons with adjusted flip angles for each channel. The proposed method is easy to implement, robust and provides homogeneous T₂*  images of the whole brain.

View Presentation Video

Pedram Yazdanbakhsh^1,2, Christian Sprang^1,3, Marcus Couch⁴, Richard Hoge^1,2,3, Christine Lucas Tardif^1,2,3, and David A. Rudko^1,2,3
1McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, QC, Canada, ²Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada, ³Department of Biomedical Engineering, McGill University, Montreal, QC, Canada, ⁴Siemens Healthcare Limited, Montreal, QC, Canada

Keywords: High-Field MRI, RF Arrays & Systems

An 8-channel transmit radiofrequency (RF) coil array consisting of eight dipoles and another 8-channel transmit coil array consisting of 8-loops were designed, constructed and compared with each other for pediatric (4-9 years old) visual cortex imaging at 7T. To ensure robust safety of the 7T parallel-transmission (pTx) coil, local SAR matrices and the commensurate virtual observation points (VOPs) has been calculated for online SAR supervision. An 8-channel receive only array consisting of eight overlapped loops covering the back of the pediatric head area has been constructed and used inside the transmit coils for visual cortex imaging.

View Presentation Video

Soo Han Soon^1,2, Hannes M. Wiesner¹, Xin Li¹, Michael T. Lanagan³, Qing X. Yang⁴, Xiao-Hong Zhu¹, and Wei Chen^1,2
1Center of Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, Minneapolis, MN, United States, ²Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States, ³Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, United States, ⁴Center for NMR Research, Department of Neurosurgery and Radiology, College of Medicine, Pennsylvania State University, Hershey, PA, United States

Keywords: High-Field MRI, New Devices, Ultrahigh dielectric constant material (uHDC)

Ultrahigh-field (UHF) deuterium (²H) magnetic resonance spectroscopy imaging (DMRSI) is valuable to study neuroenergetics by quantitatively measuring the energy metabolic rates in the human brain. However, the low intrinsic signal-to-noise ratio (SNR) of deuterium signal due to its low gyromagnetic ratio and low metabolites concentration has been a technical challenge to achieving high imaging resolution. In this study, we have integrated ultrahigh dielectric constant (uHDC) ceramic disks with an 8-channel ²H-¹H human head array coil to largely improve the receive sensitivity and DMRSI SNR (>60%) at 7T, aiming for human brain metabolic imaging application.

View Presentation Video

Busra Kahraman-Agir¹, Dimitri Welting¹, Mark Gosselink¹, and Dennis Klomp^1
1Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands

Keywords: High-Field MRI, Non-Array RF Coils, Antennas & Waveguides, multinuclei body coils, double tuned

Double-tuned circuits are often comprised of internal resonances in tank circuits that locally may amplify RF currents and thereby cause extra loss compared to single tuned RF coils. Here, we investigated the loss mechanisms of RF borecoils for the operating frequencies of 120.68, 78.8 and 45.8MHz for the purpose to design a B₁⁺ efficient multi-tuned RF borecoil for metabolic MRI of 2H, 23Na and 31P, respectively at 7T.        

 

View Presentation Video

Sergio Solis-Najera¹, Jelena Lazovic², Fabian Vazquez¹, Rodrigo Martin¹, 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: High-Field MRI, Non-Array RF Coils, Antennas & Waveguides, metamaterials

A bio-inspired surface coil was built for preclinical MRI applications at 7 T. Images were acquired with and without a flexible metasurface partially cover a cylindrical phantom. Images obtained with the metamaterial showed an important improvement of coil performance. No electronic components were used for tuning the metasurface. This easy-to-implement approach offers an alternative to improve the SNR for preclinical applications at high field. 

View Presentation Video

Giovanni Costa¹, Margarethus Maarten Paulides¹, and Irena Zivkovic^1
1Department of Electrical Engineering, Technical University of Eindhoven, Eindhoven, Netherlands

Keywords: High-Field MRI, High-Field MRI, RF arrays, transcieve coils, SCC coil

The recently proposed shielded-coaxial-cable (SCC) coils are intrinsically highly decoupled elements. Their suitability in multichannel transceiver arrays at ultra-high field was successfully demonstrated in 7T arrays. In this work, we investigated the single element and array properties of SCC coils at 9.4T. We simulated the SCC element and compared its properties (B₁⁺, SAR) with those of a conventional loop coil. Subsequently, we fabricated eight SCC coils and investigated their coupling properties when placed in various configurations. SCCs at 400MHz provided similar B₁+ and SAR efficiency, but generated ~25% less SAR_10g,max .  SCC performed well in different array configurations. 

View Presentation Video

Saba Shirvani¹, Belinda Ding², and Christopher T. Rodgers^1
1Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom, ²Research and Collaboration UK, Siemens Healthcare Ltd, Frimley, United Kingdom

Keywords: High-Field MRI, High-Field MRI, body, mr fingerprinting, tissue characterization

Abdominal 7T MRI is technically demanding but has great potential due to improved signal-to-noise ratio. One promising way to quantify tissue properties is to use MR Fingerprinting, since MRF rapidly quantifies T₁ relaxation alongside other tissue properties such as T­₂, B₁⁺ and proton density. However, translating MRF measurements from high field to ultra-high field systems is challenging. Here we investigate a strategy to translate a Cartesian MRF sequence from 3T to 7T scanners, by optimising sequence parameters. We apply this approach to the brain and to the kidney and present comparable images from our 3T and 7T scanners.

Yuanzhe Huang¹, Jinghang Li¹, Linghai Wang¹, Taylor Forry², Tamer Ibrahim¹, Howard Aizenstein¹, and Minjie Wu^1
1University of Pittsburgh, Pittsburgh, PA, United States, ²Temple University, Philadelphia, PA, United States

Keywords: High-Field MRI, Machine Learning/Artificial Intelligence

White matter lesions (WMLs), commonly found as hyperintensities (WMHs) on T2-weighted FLAIR MR brain images, are associated with neuropsychiatric and neurodegenerative disorders. In the present study, we adapted a 3D U-Net deep learning method to automatedly segment the WMHs on 3T and 7T MRI T2w FLAIR brain images. Using 3D U-Net, the accuracy of WMH segmentation is 98.8% for 3T data, while it drops to 90.3% for 7T data. However, after incorporating histogram matching in the preprocessing, the accuracy of WMHs segmentation significantly improves to 97.5% for 7T data.

View Presentation Video

Amelia Strom^1,2, Timothy G. Reese^2,3, Zijing Dong^2,3, Baarbod Ashenagar⁴, Laura D. Lewis^2,4, and Jonathan R. Polimeni^1,2,3
1Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States, ²Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ³Department of Radiology, Harvard Medical School, Boston, MA, United States, ⁴Department of Biomedical Engineering, Boston University, Boston, MA, United States

Keywords: High-Field MRI, Tissue Characterization, Neurofluids, Diffusion Imaging Techniques

Displacement Encoding with Stimulated Echoes (DENSE) MRI was used to estimate pons and midbrain tissue displacement over the cardiac cycle at 2-mm, 3-mm, and 4-mm isotropic spatial resolutions in individual subjects at 7T. Displacement estimates were largest at 2-mm resolution and matched previous reports of peak brainstem displacement over the cardiac cycle. Smaller estimates at lower resolution may be due to partial volume effects from the surrounding tissue or CSF.

View Presentation Video

Hoby Hetherington¹, Junghwan Kim², Melissa Terpstra², and Jullie Pan^2
1Resonance Research Inc., Billerica, MA, United States, ²Radiology, University of Missouri, Columbia, MO, United States

Keywords: Shims, Shims

B₀ shimming for single voxel spectroscopy (SVS) is of importance due to its role in determining linewidth, accuracy of the analysis and interpretation. However, for difficult brain regions, such as the prefrontal cortex, where shifts of 3-6mm in voxel position can dramatically alter the achieved linewidth in SVS, the lack of a reliable method to predict the achievable homogeneity results in failed studies and/or increased study times. In this work we demonstrate an objective and non-iterative method (SUMO) for voxel positioning that predicts and ensures adequate B₀ homogeneity is achievable.