Review
Engineering, Biomedical
Sydney N. Williams, Paul McElhinney, Shajan Gunamony
Summary: This paper reviews the use of multiple or parallel radiofrequency (RF) transmission for magnetic resonance imaging (MRI). It discusses the challenges faced with non-uniformity of the RF field and higher RF power deposition in ultra-high field (UHF) MRI. The paper highlights the benefits of parallel transmission (pTx) in overcoming these challenges and provides an overview of the types of RF coils used for pTx. It also discusses safety considerations and applications of pTx in RF pulse design.
PHYSICS IN MEDICINE AND BIOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Le Yuan, Zhenglei Wang, Wenqi Wei, Xiaotao Han
Summary: This article introduces an approximately symmetrical TR switch topology based on PIN diodes and multiple sections of coplanar waveguide lines for high-frequency broadband PMF-NMR experiments. Excellent parameters are obtained through optimization and error evaluation. The switch has a bandwidth of 250 MHz-1 GHz, an insertion loss of less than 0.56 dB, a switching time of less than 0.9 microseconds, and a high-power capacity of 200 W.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2023)
Article
Biophysics
Ole Geldschlaeger, Dario Bosch, Anke Henning
Summary: The purpose of this study was to optimize transmit k-space trajectories and design universal pTx RF pulses. By optimizing trajectories and comparing the performance of different RF pulse designs, it was found that using optimized trajectories was crucial for pulse performance and that target specific universal pulses could be created. However, not every test target was suitable for universal pulse design. In vivo experiments showed a high degree of similarity between subject specific tailored pulses and universal pulses.
NMR IN BIOMEDICINE
(2022)
Article
Materials Science, Multidisciplinary
Mohammad K. Anvarifard
Summary: This paper reports on the non-linearity and radio-frequency intermodulation distortion in ultrascale graphene-nanoribbon-field-effect-transistors (GNRFETs), exploring important figure of merits and parameters to evaluate power and performance in RF applications. Structural parameters and numerical approaches are investigated to determine the best setup for ultrascale GNRFET device applicable in RF applications, benefiting from a self-consistent manner and accurate simulation models.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Mohamed A. Abou-Khousa, Ademola A. Mustapha
Summary: The utility of wideband high field nuclear magnetic resonance (NMR) spectrometers is essential in various applications. This brief introduces a new design of wideband high-power TR switch for multi-nuclei NMR spectrometers. Experimental results show that the switch has a wide bandwidth, low insertion loss, and high isolation.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Xiaoxuan He, Edward J. Auerbach, Michael Garwood, Naoharu Kobayashi, Xiaoping Wu, Gregory J. Metzger
Summary: The study aimed to develop a 3D composite adiabatic pulse for spectroscopic acquisitions and compare its performance against standard methods. The designed pulse achieved simultaneous 2D spatial localization with water and lipid suppression, allowing for high-quality spectra at shorter TE/TR.
MAGNETIC RESONANCE IN MEDICINE
(2021)
Article
Chemistry, Physical
Zulhumar Turup, Xiaoyu Yang, Pengwei Li, Hongfang Wang, Jingyu Wang, Min Gao
Summary: The properties of plasmonic hot spots in particle-on-film structures were investigated under oblique incidence. It was found that the hot spots were circularly distributed around the junction at specific wavelengths, and their locations could be manipulated by adjusting the incidence angle.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Engineering, Electrical & Electronic
Waqas Ahmad, Haibo Zhang, Yawen Chen, Naveed Iqbal
Summary: This paper proposes a low RF-complexity digital beamforming architecture that allows a small number of RF chains to serve a large number of transmit antennas. By dynamically grouping the transmit antennas, each antenna group forms a close-to-rank-one channel matrix with the receive antennas. The architecture outperforms full RF-complexity DBF when considering hardware imperfections.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Sen Yan, Hao Ma, Yi-Fan Bao, Maofeng Cao, Chuan Liu, Kaifeng Zhang, Xiaowei Wu, Jianbo He, Xiang Wang, Bin Ren
Summary: In this study, a series of plasmonic array structures with different unit numbers were fabricated using focused ion beam (FIB) technology. The effects of the array structures on optical response were investigated using photoluminescence (PL) and surface-enhanced Raman spectroscopy (SERS). It was found that the array units outside the excitation spot still have a significant impact on the optical response, due to the loss of propagating surface plasmon polaritons (PSPPs) outside the excitation point caused by the finite array boundary. This research advances the understanding of near-field and far-field optical behavior in finite-size array structures, and provides guidance for designing highly efficient photonic devices.
Article
Engineering, Biomedical
Haiwei Chen, Lei Guo, Mingyan Li, Aurelien Destruel, Chunyi Liu, Ewald Weber, Feng Liu, Stuart Crozier
Summary: In this study, capacitors and metallic interconnectors were used to miniaturize metamaterial absorbers (MA) for use as a novel RF shield in MRI systems. The MA-RF shield significantly improved transmit efficiency of RF surface coils and reduced specific absorption rate (SAR) compared to conventional RF shields. The proof-of-concept study demonstrated an innovative practical way for utilizing metamaterials in ultra-high field MRI applications.
IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING
(2021)
Article
Computer Science, Information Systems
Li Zhang, Jiliang Zhang, Nana Hu, Xingyi Li, Gaofeng Pan
Summary: In this article, the outage performance of a dual-hop free space optical-radio frequency communication system is investigated. The system consists of a source node, two users, and a single-aperture and multi-antenna relay. The relay can harvest energy from a power beacon, and two transmitting antenna selection (AS) criteria are considered to improve the outage performance. The closed-form expressions of the outage probability for each user under both AS schemes are derived and validated through Monte-Carlo simulation.
IEEE INTERNET OF THINGS JOURNAL
(2023)
Article
Multidisciplinary Sciences
Song Jiang, Tomas Neuman, Alex Boeglin, Fabrice Scheurer, Guillaume Schull
Summary: In this study, the intrinsic optoelectronic properties of graphene nanoribbons (GNRs) were explored using a scanning tunneling microscope-based method. By transferring the GNRs onto a partially insulating surface, luminescence quenching effects were prevented and localized dark excitons associated with the topological end states of the GNRs were observed.
Article
Chemistry, Physical
Mariya Romanova, Guorong Weng, Arsineh Apelian, Vojtech Vlcek
Summary: We present a method to treat localized correlated electronic states in a weakly correlated host medium. The method involves dynamically downfolding the environment on the correlated subspace and renormalizing the quasiparticle interaction terms using many-body perturbation theory. We go beyond static limit approximation to account for dynamical effects and introduce an efficient stochastic implementation for large host environments. We demonstrate the method by reproducing optical excitations in the NV center defect in diamond.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Physics, Applied
R. B. Morgunov, R. S. Allayarov, E. I. Kunitsyna, O. V. Koplak
Summary: Ferromagnetic microparticles affect spin relaxation in Er3+ single-ion magnet in a composite material. The balance of thermal spin noise is changed in Er3+ complexes due to the influence of surrounding ferromagnetic matrix. The electron spin noise controlled by ferromagnetic media has two competing sources.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Biomedical
Zachary A. A. Colwell, Lance DelaBarre, Djaudat Idiyatullin, Gregor Adriany, Michael Garwood, J. Thomas Vaughan, Sung-Min Sohn
Summary: In this study, a standalone RF self-interference canceller for 1.5T simultaneous transmit and receive (STAR) magnetic resonance imaging (MRI) was developed. The system achieved high isolation by manipulating a cancellation signal with voltage-controlled attenuators and phase shifters to match the leakage signal between transmit and receive RF coils. The cancellation signal was initially generated by a voltage-controlled oscillator (VCO) and calibrated by tapping the receive signal. The system achieved 74.2 dB of isolation with a 94-second calibration time. In-vivo MR images were obtained with approximately 40 mW of RF peak power. Evaluation: 9/10.
IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS
(2023)
Article
Clinical Neurology
Kevin R. Keene, Johan M. de Nie, Mechteld J. Brink, Irene C. Notting, Jan J. G. M. Verschuuren, Hermien E. Kan, Jan-Willem M. Beenakker, Martijn R. Tannemaat
Summary: This study aimed to explore whether orthoptic measures, including an adapted Hess chart examination, can aid in diagnosing ocular myasthenia gravis (MG). The results showed that orthoptic measurements can be used to diagnose MG by quantifying extraocular muscle (EOM) weakness and fatiguability. Drift during persistent gaze on a Hess chart was found to be specific for MG, and could be used for diagnostic purposes.
JOURNAL OF NEUROLOGY NEUROSURGERY AND PSYCHIATRY
(2023)
Review
Pharmacology & Pharmacy
Joshua Koslover, Deborah Bruce, Shivani Patel, Andrew J. Webb
Summary: We reviewed the pharmacological and prescribing principles of metformin using the mnemonic framework 'BRAINS & AIMS' (Benefits, Risks, Adverse Effects, Interactions, Necessary prophylaxis, Susceptibilities, Administering, Informing, Monitoring, and Stopping). Metformin is used for the treatment of type 2 diabetes mellitus (T2DM) and in reducing the risk or delaying the onset of the disease. However, there is no clear evidence that metformin influences patient-important outcomes. The drug is inexpensive and considered essential by WHO, but contraindicated or not tolerated in 15% of patients, such as those with renal impairment and a risk of lactic acidosis. Common adverse effects include gastrointestinal side effects and vitamin B-12 deficiency. Interactions may occur with drugs impairing renal function and those inhibiting specific transporters. It is necessary to detect and treat vitamin B-12 deficiency and consider the susceptibility of certain patient groups. The administration of metformin should start with a low dose and be titrated slowly. Renal function, HbA1c, and vitamin B-12 levels need to be monitored regularly. Stopping metformin is not associated with harm and should be considered in patients with worsening renal or liver function.
BRITISH JOURNAL OF CLINICAL PHARMACOLOGY
(2023)
Editorial Material
Pharmacology & Pharmacy
Andrew J. J. Webb
BRITISH JOURNAL OF CLINICAL PHARMACOLOGY
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Wyger M. Brink, Rob F. Remis, Andrew G. Webb
Summary: This study evaluates the impact of insulation material between high permittivity dielectric pads and the body using RF simulations and phantom experiments. The results show that removing the insulation material increases RF heating, indicating the importance of considering insulation properties for RF safety assessment.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Biology
Tooba Abbassi-Daloii, Salma el Abdellaoui, Lenard M. Voortman, Thom T. J. Veeger, Davy Cats, Hailiang Mei, Duncan E. Meuffels, Ewoud van Arkel, Peter Bram 't Hoen, Hermien Kan, Vered Raz
Summary: We constructed a large atlas of RNA-seq profiles from leg muscles, identifying differential expression patterns and cellular composition across different tissues. The muscle samples were clustered into three groups based on anatomical location, which were associated with oxidative metabolism and fast- or slow-twitch myofibers. Expression profiles of Homeobox transcription factors differed between the three groups. Our study provides a novel resource to study muscle-specific molecular features and their potential links to physiological processes.
Article
Clinical Neurology
Giacomo P. Comi, Erik H. Niks, Krista Vandenborne, Claudia M. Cinnante, Hermien E. Kan, Rebecca J. Willcocks, Daniele Velardo, Francesca Magri, Michela Ripolone, Jules J. van Benthem, Nienke M. van de Velde, Simone Nava, Laura Ambrosoli, Sara Cazzaniga, Paolo U. Bettica
Summary: This study investigated the efficacy and safety of givinostat in adults with Becker muscular dystrophy (BMD). The primary endpoint of statistical superiority for mean change in total fibrosis was not achieved. However, MRI assessments suggested that givinostat may potentially prevent or slow down BMD disease progression.
FRONTIERS IN NEUROLOGY
(2023)
Article
Clinical Neurology
Jasmin Annica Keller, Sigurdur Sigurdsson, Kelly Klaassen, Lydiane Hirschler, Mark A. A. van Buchem, Lenore J. J. Launer, Matthias J. P. van Osch, Vilmundur Gudnason, Jeroen H. J. M. de Bresser
Summary: This study aimed to investigate the association between the shape and volume of white matter hyperintensity (WMH) and the long-term risk of dementia in community-dwelling older adults. The results showed that an irregular shape of periventricular/confluent WMH, higher WMH volume, and higher deep WMH volume were associated with an increased risk of dementia.
ALZHEIMERS & DEMENTIA
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Aashley S. D. Sardjoe Mishre, Borja Martinez-Tellez, Maaike E. Straat, Mariette R. Boon, Oleh Dzyubachyk, Andrew G. Webb, Patrick C. N. Rensen, Hermien E. Kan
Summary: This study demonstrates that coregistration and mutual thresholding can improve the variability in measuring fat fraction, and enhance the assessment stability of fat fraction changes in supraclavicular brown adipose tissue following cold exposure.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Review
Radiology, Nuclear Medicine & Medical Imaging
Adrienne E. Campbell-Washburn, Kathryn E. Keenan, Peng Hu, John P. Mugler, Krishna S. Nayak, Andrew G. Webb, Johnes Obungoloch, Kevin N. Sheth, Juergen Hennig, Matthew S. Rosen, Najat Salameh, Daniel K. Sodickson, Joel M. Stein, Jose P. Marques, Orlando P. Simonetti
Summary: The first ISMRM Workshop on Low-Field MRI was held virtually in March 2022, discussing recent advancements in low field MRI technology and its clinical applications. With 368 registrants from 24 countries, the workshop included invited talks, abstract presentations, panel discussions, and live scanner demonstrations. The workshop emphasized the potential of low-field MRI in expanding MRI usage through cost reduction, portability, and ease of installation, as well as the challenges in overcoming SNR limitations and establishing clinical value.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Geriatrics & Gerontology
Donnie Cameron, Tooba Abbassi-Daloii, Laura G. M. Heezen, Nienke M. van de Velde, Zaida Koeks, Thom T. J. Veeger, Melissa T. Hooijmans, Salma el Abdellaoui, Sjoerd G. van Duinen, Jan J. G. M. Verschuuren, Maaike van Putten, Annemieke Aartsma-Rus, Vered Raz, Pietro Spitali, Erik H. Niks, Hermien E. Kan
Summary: This study used DT-MRI to compare muscle fiber diameter between BMD patients and healthy controls and found that BMD patients had significantly larger muscle fiber diameter. The results of DT-MRI were consistent with histology, suggesting that it can be used as an imaging biomarker for muscular dystrophies without the need for invasive biopsies.
JOURNAL OF CACHEXIA SARCOPENIA AND MUSCLE
(2023)
Article
Clinical Neurology
Kevin R. Keene, Irene C. Notting, Jan J. G. M. Verschuuren, N. Voermans, Ronald. O. B. de Keizer, Jan-Willem M. Beenakker, Martijn R. Tannemaat, Hermien E. Kan
Summary: Quantitative MRI was used to study the extra-ocular muscles (EOM) in patients with myasthenia gravis (MG). The study found that chronic MG patients showed small increases in EOM volume and muscle fat fraction (FF), while patients with chronic progressive external ophthalmoplegia (CPEO) showed decreased volume and patients with Graves' ophthalmopathy (GO) showed increased volume. The severity of ophthalmoplegia in MG was not correlated with EOM volume, but was correlated in CPEO and oculopharyngeal muscular dystrophy (OPMD).
JOURNAL OF NEUROMUSCULAR DISEASES
(2023)
Article
Clinical Neurology
Sam Geuens, Jeroen Van Dessel, Rosanne Govaarts, Nadine A. Ikelaar, Onno C. Meijer, Hermien E. Kan, Erik H. Niks, Nathalie Goemans, Jurgen Lemiere, Nathalie Doorenweerd, Liesbeth De Waele
Summary: This study investigated the impact of corticosteroid treatment on brain volumetrics in Duchenne muscular dystrophy (DMD) patients. The results showed regional differences in gray matter volumes between the patient groups and the control group, with daily corticosteroid treatment showing a greater overall difference.
ANNALS OF CLINICAL AND TRANSLATIONAL NEUROLOGY
(2023)
Review
Radiology, Nuclear Medicine & Medical Imaging
Andrew Webb, Thomas O'Reilly
Summary: This study aims to review the major hardware components of low-field point-of-care MRI systems that affect the overall sensitivity. The designs of magnet, RF coils, transmit/receive switches, preamplifiers, data acquisition system, and methods for grounding and mitigating electromagnetic interference are reviewed and analyzed. The results show that high homogeneity magnets can be produced in various designs and using Litz wire for RF coil designs enables high Q values. Different schemes are available to address the low coil bandwidth issue. Good RF shielding, proper electrical grounding, and effective electromagnetic interference reduction can lead to substantial increases in image signal-to-noise ratio. It is suggested that a standardized set of sensitivity measures should be determined for meaningful comparisons and optimizations.
MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Javad Parsa, Andrew Webb
Summary: The study aims to simulate the magnetic and electric fields produced by commonly used RF coil geometries at low field, and to derive the specific absorption rate (SAR) efficiency based on these simulations. The results showed that SAR efficiency needs to be carefully considered only when using TSE sequences with 180 degrees refocusing pulses of duration similar to 10 ms.
MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE
(2023)