Article
Radiology, Nuclear Medicine & Medical Imaging
Caroline Le Ster, Franck Mauconduit, Aurelien Massire, Nicolas Boulant, Vincent Gras
Summary: This study introduces the concept of standardized universal pulses (SUPs), which improves excitation accuracy while reducing the computational burden and expertise required.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Optics
Shuai Zhang, Xi Hou, Wei Yan, Yuancheng Zhao, Xiaochuan Hu, Yutong Meng, Mengfan Li
Summary: In this paper, a multi-dimensional stitching method using thickness alignment (MSuTA) is proposed for measuring the surfaces and thickness of large thin parallel plates. It uses the sub-aperture stitching method based on wavelength-tuned interferometer (WTI) and establishes a stitching correction model based on Legendre polynomials. The method improves the lateral resolution of the measurement and provides more comprehensive surface information.
Article
Radiology, Nuclear Medicine & Medical Imaging
Jun Ma, Bernhard Gruber, Xinqiang Yan, William A. Grissom
Summary: The proposed k-space domain algorithm accelerates and finely parallelizes parallel transmission pulse design, reducing the memory required to store the design matrix, but with a modest tradeoff of excitation error and RMS RF amplitude.
MAGNETIC RESONANCE IN MEDICINE
(2021)
Article
Biophysics
Roger Ordidge, Jon Cleary, Rebecca Glarin, Yasmin Blunck, Shawna Farquharson, Brad Moffat
Summary: In this paper, the use of new variations of composite RF pulses (STEP) in ultra-high field MRI is explored to address technical challenges associated with non-uniform B-1 excitation fields. Different techniques based on STEP sequences are introduced and successfully applied in human brain imaging.
NMR IN BIOMEDICINE
(2021)
Article
Chemistry, Multidisciplinary
Honglei Che, Congling Shi, Yu Wang
Summary: In this paper, two types of transmission angles are defined to evaluate the kinematic performance of parallel manipulators and are investigated in relation to the condition number of the Jacobian matrix. Simulation studies are conducted to prove the effectiveness of these transmission angles for robots.
APPLIED SCIENCES-BASEL
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Bobby A. Runderkamp, Thomas Roos, Wietske van der Zwaag, Gustav J. Strijkers, Matthan W. A. Caan, Aart J. Nederveen
Summary: This study aimed to achieve homogeneous signal throughout the human liver at 7 T. By using subject-specific multichannel absolute B-1(+) maps and parallel-transmit k(T)-point pulses for flip angle (FA) shimming, homogeneous whole-liver images were obtained.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Optics
Andre Perennou, Veronique Quintard, Adan Omar Arellanes
Summary: The study proposes the use of an arbitrary waveform generator to create a specific radio frequency (RF) signal for an acousto-optic tunable filter. By controlling the acoustic pulse, the filter's transmission function can be changed in terms of selectivity and side-lobe levels. The measurement results show agreement with the simulation model, and the Hamming window effectively suppresses side lobes in the transmission function even at high acoustic powers.
Article
Radiology, Nuclear Medicine & Medical Imaging
David Leitao, Raphael Tomi-Tricot, Pip Bridgen, Tom Wilkinson, Patrick Liebig, Rene Gumbrecht, Dieter Ritter, Sharon L. Giles, Ana Baburamani, Jan Sedlacik, Joseph Hajnal, Shaihan J. Malik
Summary: This work introduces a novel RF pulse design for pTx systems to achieve uniform saturation of semisolid magnetization and enhance MT contrast. By optimizing the pulse design, significant improvements in Brms 1 homogeneity and MT contrast are achieved. The proposed method shows superior performance in experiments, providing higher uniformity and contrast compared to traditional methods.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Marco Andrea Zampini, Jan Sijbers, Marleen Verhoye, Ruslan Garipov
Summary: This study investigates the design of a preparation module for B-1 mapping, and validates its features and robustness through simulations and experiments. The results show that the module has advantages in low flip angle and AFI sequences that sample the center of the k-space early, reducing scanner overhead time.
Article
Biophysics
Zihua Qian, Ruibin Liu, Zhe Wu, Yi-Cheng Hsu, Caixia Fu, Yi Sun, Dan Wu, Yi Zhang
Summary: In this study, a simultaneous parallel transmission-based CEST sequence was proposed to achieve a longer saturation duration and improved RF saturation homogeneity. The sequence was optimized and tested in phantom models and human subjects, demonstrating improved image contrast and signal uniformity. The proposed method enables longer saturation duration at a 100% duty cycle and reduces the dielectric shading effects.
NMR IN BIOMEDICINE
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Simon Levy, Juergen Herrler, Andrzej Liebert, Katharina Tkotz, Moritz S. Fabian, Christian Eisen, David Grodzki, Michael Uder, Arnd Doerfler, Moritz Zaiss, Armin M. Nagel
Summary: This study evaluates the benefits and challenges of dynamic parallel transmit (pTx) pulses for fat saturation (FS) and water-excitation (WE) in CEST MRI. The results show that pTx improves fat saturation and water excitation homogeneity, but spectral selectivity is reduced in certain areas.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Biophysics
Beatrice Lena, Clemens Bos, Cyril J. Ferrer, Chrit T. W. Moonen, Max A. Viergever, Lambertus W. Bartels
Summary: This study proposed a slice profile correction method based on Bloch simulation, which effectively reduced slice profile errors in 2D VFA T1 mapping, improving precision and accuracy. The method can provide accurate and precise T1 estimates within 5% over a wide range of T1 values.
NMR IN BIOMEDICINE
(2021)
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
Physics, Fluids & Plasmas
Caleb Richards, Elijah Jans, Ilya Gulko, Keegan Orr, Igor Adamovich
Summary: In this study, the vibrational and translational-rotational temperatures in quasi-two-dimensional atmospheric pressure plasma jets sustained by ns pulse and RF discharges in nitrogen/noble gas mixtures were measured using broadband vibrational Coherent Anti-Stokes Raman Scattering (CARS). The results show that the RF plasma jets have stronger vibrational excitation compared to the ns pulse discharge, and the vibrational temperature in the ns pulse discharge is affected by the presence of helium atoms. The experimental data in the RF plasma jet in N-2/Ar are compared with kinetic modeling predictions.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Rui Zhe Jiang, Jun Wei Wu, Qian Ma, Jing Cheng Liang, Li Jie Wu, Qun Yan Zhou, Jun Yan Dai, Qiang Cheng, Tie Jun Cui
Summary: Glass windows play a crucial role in indoor-to-outdoor wireless communication channels, but the transmission loss of regular glass hinders the quality of radio frequency (RF) signals, particularly for wide-angle high incidence TE-polarized waves due to the impedance mismatch. This study presents an optically transparent metasurface for high RF transmission in dual polarizations and dual bands, with wide incidence angles. The design can independently tune the central frequencies of the two bands, and a prototype based on flexible printed circuit technology is successfully fabricated and validated.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Daniel Polak, Daniel Nicolas Splitthoff, Bryan Clifford, Wei-Ching Lo, Susie Y. Huang, John Conklin, Lawrence L. Wald, Kawin Setsompop, Stephen Cauley
Summary: The SAMER technique utilizes accelerated scout scans and novel sequence reordering to achieve clinically acceptable motion estimation and reconstruction time. It demonstrates high accuracy and stability in both simulation and in vivo evaluation, enabling high-quality imaging and retrospective motion estimation.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Sai Abitha Srinivas, Stephen F. Cauley, Jason P. Stockmann, Charlotte R. Sappo, Christopher E. Vaughn, Lawrence L. Wald, William A. Grissom, Clarissa Z. Cooley
Summary: The EDITER method introduced in this study is an external sensor-based method to remove image artifacts caused by external interference sources in portable MRI systems. Experimental results demonstrate the effectiveness of the method in reducing EMI in phantom and in vivo imaging experiments, as well as increasing image signal-to-noise ratio.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Markus W. May, Sam-Luca J. D. Hansen, Mirsad Mahmutovic, Alina Scholz, Nicolas Kutscha, Bastien Guerin, Jason P. Stockmann, Robert L. Barry, Ehsan Kazemivalipour, Rene Gumbrecht, Ralph Kimmlingen, Markus Adriany, Yulin Chang, Christina Triantafyllou, Susanne Knake, Lawrence L. Wald, Boris Keil
Summary: This study aimed to extend the coverage of brain coil arrays to the neck and cervical-spine region for combined head and neck imaging at 7 Tesla ultra-high field MRI. The results showed that the constructed coil array improved the SNR in the face area, neck area, and cervical spine, and it also showed improved accelerated imaging capabilities. Overall, this new head-neck array coil has great potential in improving neuroimaging applications at ultra-high field strength.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Correction
Radiology, Nuclear Medicine & Medical Imaging
Valerie Klein, Mathias Davids, Lothar R. Schad, Lawrence L. Wald, Bastien Guerin
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Zijing Dong, Fuyixue Wang, Lawrence Wald, Kawin Setsompop
Summary: ACE-EPTI is an efficient technique for high-resolution diffusion imaging and diffusion-relaxometry, providing high SNR, distortion-free, and time-resolved multi-echo images.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Neurosciences
Fuyixue Wang, Zijing Dong, Timothy G. Reese, Bruce Rosen, Lawrence L. Wald, Kawin Setsompop
Summary: 3D-EPTI is a novel approach that increases the acceleration capacity of MRI sampling and provides high acquisition efficiency for multi-parametric MRI. It exploits the spatiotemporal correlation of MRI data to achieve faster sampling and enables high-resolution multi-parametric imaging for studying complex brain processes.
Article
Radiology, Nuclear Medicine & Medical Imaging
Valerie Klein, Jaume Coll-Font, Livia Vendramini, Donald Straney, Mathias Davids, Natalie G. Ferris, Lothar R. Schad, David E. Sosnovik, Christopher T. Nguyen, Lawrence L. Wald, Bastien Guerin
Summary: The study measured cardiac magnetostimulation thresholds in pigs and found that the IEC cardiac safety limit may be overly conservative for the investigated stimulus duration.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Neurosciences
Qiuyun Fan, Cornelius Eichner, Maryam Afzali, Lars Mueller, Chantal M. W. Tax, Mathias Davids, Mirsad Mahmutovic, Boris Keil, Berkin Bilgic, Kawin Setsompop, Hong-Hsi Lee, Qiyuan Tian, Chiara Maffei, Gabriel Ramos-Llorden, Aapo Nummenmaa, Thomas Witzel, Anastasia Yendiki, Yi-Qiao Song, Chu-Chung Huang, Ching-Po Lin, Nikolaus Weiskopf, Alfred Anwander, Derek K. Jones, Bruce R. Rosen, Lawrence L. Wald, Susie Y. Huang
Summary: In the past decade, tremendous efforts have been made to advance cutting-edge MRI technology in order to map the structural connectivity in the living human brain. This review article summarizes the technical developments in using the Connectom scanner for large-scale and scientific studies of the human brain, and discusses the scientific impact of the Connectom MRI scanner.
Article
Clinical Neurology
M. Lang, A. Tabari, D. Polak, J. Ford, B. Clifford, W. -C. Lo, K. Manzoor, D. N. Splitthoff, L. L. Wald, O. Rapalino, P. Schaefer, J. Conklin, S. Cauley, S. Y. Huang
Summary: The SAMER framework was evaluated in 97 clinical brain MRI examinations and found to significantly improve motion artifacts, especially in cases with moderate or severe motion.
AMERICAN JOURNAL OF NEURORADIOLOGY
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Valerie Klein, Mathias Davids, Livia Vendramini, Natalie G. Ferris, Lothar R. Schad, David E. Sosnovik, Christopher T. Nguyen, Lawrence L. Wald, Bastien Guerin
Summary: Coupled electromagnetic-electrophysiological modeling in detailed body and heart models can predict cardiac stimulation thresholds, which can lead to more detailed threshold estimates in humans. Experimental and predicted thresholds in eight pigs showed good agreement. This modeling approach can be applied to study cardiac stimulation thresholds in humans for various conditions.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Mathias Davids, Peter Dietz, Gudrun Ruyters, Manuela Roesler, Valerie Klein, Bastien Guerin, David A. Feinberg, Lawrence L. Wald
Summary: By analyzing various aspects of head gradient design using a detailed peripheral nerve stimulation (PNS) model, we have successfully designed a new high-performance asymmetric head gradient coil to raise PNS thresholds and maximize usable image-encoding performance.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Filiz Yetisir, Esra Abaci Turk, Elfar Adalsteinsson, Lawrence Leroy Wald, Patricia Ellen Grant
Summary: This study evaluates the imaging performance of two-channel RF-shimming for fetal MRI at 3 T using four different local specific absorption rate (SAR) management strategies. The results show that the use of subject-specific models with local SAR limits based on maximum CP mode SAR levels in the pregnant population can safely and significantly improve the transmit field inside the fetus.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Ehsan Kazemivalipour, Lawrence L. Wald, Bastien Guerin
Summary: This study models the performance of parallel transmission arrays with different channel numbers for brain imaging and compares them with birdcage coils and cylindrical pTx coils. The results show that helmet designs outperform cylindrical pTx arrays in terms of local specific absorption rate and flip-angle uniformity, especially for non-transverse slice excitations.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Engineering, Biomedical
Erica E. Mason, Eli Mattingly, Konstantin Herb, Stephen F. Cauley, Monika Sliwiak, John M. Drago, Matthias Graeser, Emiri T. Mandeville, Joseph B. Mandeville, Lawrence L. Wald
Summary: This study evaluates magnetic particle imaging (MPI) as a new functional imaging modality by mapping the cerebral blood volume (CBV) response. The results show that MPI has higher sensitivity than functional magnetic resonance imaging (fMRI) in detecting changes in CBV.
PHYSICS IN MEDICINE AND BIOLOGY
(2023)