Article
Radiology, Nuclear Medicine & Medical Imaging
Santhosh Iyyakkunnel, Matthias Weigel, Carl Ganter, Oliver Bieri
Summary: The study presents a new complex-valued B-1(+) mapping method using Carr-Purcell spin echoes for electrical properties tomography. Results show good agreement between B-1(+) magnitude retrieved from CP echo train and AFI method in phantom and brain scans, with estimated permittivity and conductivity values matching expectations.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Multidisciplinary Sciences
Luca Vizioli, Steen Moeller, Logan Dowdle, Mehmet Akcakaya, Federico De Martino, Essa Yacoub, Kamil Ugurbil
Summary: The study introduces a denoising technique that improves key metrics of fMRI experiments while leaving other parameters unchanged. This method enables the acquisition of ultrahigh resolution functional maps and is beneficial for a variety of fMRI applications.
NATURE COMMUNICATIONS
(2021)
Article
Optics
Chongyin Yi, Shuna Yang, Bo Yang, Tao Jin, Hao Chi
Summary: A novel photonic approach for generating switchable multi-format chirp RF waveforms using a dual-parallel Mach-Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. The experiments show that different chirp RF waveforms with doubled bandwidths can be generated, suitable for multifunctional radars. The proposed scheme features compact structure, ease of switching control, and bandwidth doubling capabilities.
Article
Computer Science, Interdisciplinary Applications
Jae Eun Song, Dong-Hyun Kim
Summary: This paper proposes a nonlinear dimensionality reduction method to improve the accuracy of myelin water fraction (MWF) imaging, by extracting low-dimensional features of complex-valued signals and using sparse regularization to separate anomaly sources. The proposed method outperforms conventional approaches and maintains robustness against noise and artifact corruption.
IEEE TRANSACTIONS ON MEDICAL IMAGING
(2022)
Article
Chemistry, Analytical
Xiangjian Meng, Wen Xu, Binjian Shen, Xinxin Guo
Summary: This study proposes a sonar simulator based on a two-level network architecture, which has a flexible task scheduling system and extensible data interaction organization. By simulating underwater acoustic propagation and sonar principles to restore actual experimental scenarios, the simulator provides reasonable research conditions for guiding development and fault diagnosis. Several seabed models are arranged to test the simulation algorithms, and the actual experiment results are compared to demonstrate the application value of this sonar simulator.
Article
Radiology, Nuclear Medicine & Medical Imaging
Anysia Poncelet, Markus Weiler, Ute Hegenbart, Georges Sam, Stefan Schoenland, Jan C. Purrucker, John M. Hayes, Ernst Hund, Martin Bendszus, Sabine Heiland, Jennifer Kollmer
Summary: The study aimed to compare T2 relaxometry data obtained from dual-echo TSE and 12-echo MSE sequences for quantifying peripheral nerve lesions, demonstrating that they provide equally robust and reliable results in calculating T2app and proton spin density (rho).
INVESTIGATIVE RADIOLOGY
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Philip K. Lee, Brian A. Hargreaves
Summary: A joint linear reconstruction method is proposed for multishot quadratic phase increment data in DW-FSE sequences, addressing the issues of signal loss and ghosting. The results from phantom and in vivo experiments demonstrate the effectiveness of this method in reconstructing multishot images and improving performance.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Soozy Jung, JiSu Yun, Deog Young Kim, Dong-Hyun Kim
Summary: In this study, an improved MWF mapping method using complex-valued neural network analysis was proposed. The method showed better quantitative results by considering fiber orientation effects and correcting biases and artifacts. Additionally, uncertainty estimates were provided as a confidence interpretation of the output.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Chemistry, Physical
Luis Fabregas-Ibanez, Valerie Mertens, Irina Ritsch, Tona von Hagens, Stefan Stoll, Gunnar Jeschke
Summary: This paper presents an extension to the dipolar pathways model, which is applicable to multi-dimensional dipolar EPR experiments. By studying 4-pulse DEER and TRIER experiments, the authors verify the theoretical predictions and achieve analysis of previously challenging datasets and extraction of distance distributions.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Christian Kames, Jonathan Doucette, Alexander Rauscher
Summary: This study proposes a multi-echo field-to-source forward model that can reconstruct tissue magnetic susceptibility without fitting multi-echo phase data. The model achieves state-of-the-art results on the QSM Challenge 2.0 datasets. Additionally, a correction step is introduced to partially recover underestimated low-frequency susceptibility distributions.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Computer Science, Artificial Intelligence
Yael Balbastre, Mikael Brudfors, Michela Azzarito, Christian Lambert, Martina F. Callaghan, John Ashburner
Summary: Quantitative MR imaging is gaining popularity, but noise in parameter maps is a common issue. This study proposes a probabilistic generative model to jointly recover parameter maps, achieving rapid and stable convergence with a second order optimization method. Implemented with PyTorch, the framework can further decrease noise in maps.
MEDICAL IMAGE ANALYSIS
(2021)
Article
Radiology, Nuclear Medicine & Medical Imaging
Binyu Ouyang, Qizhi Yang, Xiaoyin Wang, Hongjian He, Lingceng Ma, Qinqin Yang, Zihan Zhou, Shuhui Cai, Zhong Chen, Zhigang Wu, Jianhui Zhong, Congbo Cai
Summary: In this study, a new single-shot magnetic resonance imaging method was proposed to improve the accuracy of T-2 mapping using multiple echo-train techniques. Experimental results demonstrated that this method outperforms the traditional methods in terms of quantitative accuracy and tissue details. Additionally, it can correct the signal deviations caused by the inaccuracy of refocusing pulses and has high repeatability.
Article
Radiology, Nuclear Medicine & Medical Imaging
Yiqi Hu, Chenao Zhan, Zhenlu Yang, Xiaoyong Zhang, Huiting Zhang, Wei Liu, Liming Xia, Tao Ai
Summary: The study found that SMS rs-EPI significantly reduces scan time and demonstrates good linear relationships and similar diagnostic performance compared to conventional rs-EPI. SMS rs-EPI provides comparable image quality to conventional rs-EPI without sacrificing SNR or CNR.
EUROPEAN RADIOLOGY
(2021)
Article
Physics, Multidisciplinary
A. R. Mohammed, T. M. El-Shahat, N. Metwally
Summary: The study investigates the possibility of generating a multi-hop network between different entangled nodes using spin Dipolar interaction. It is found that the correlations between nodes depend on the initial network settings, with correlations between three nodes being more robust than those between two nodes. Additionally, the direction and strength of interaction have a significant effect on the correlation behavior between two nodes, while having a minor impact on the correlation of three nodes.
INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS
(2021)
Article
Biochemical Research Methods
Sang-Han Choi, Jun-Young Chung, Dae-Hun Kang, Kyoung-Min Lee
Summary: This study introduces a new functional brain analysis approach, white noise-removed true T2*-variation mapping, which integrates traditional mapping methods for activation mapping and resting-state imaging. Experimental results demonstrate reliable activation mapping in the visual cortex area and default mode network region with white noise and S0 component removed.
JOURNAL OF NEUROSCIENCE METHODS
(2021)
Article
Radiology, Nuclear Medicine & Medical Imaging
Martin Soellradl, Johannes Strasser, Andreas Lesch, Rudolf Stollberger, Stefan Ropele, Christian Langkammer
Summary: The adaptive slice-specific compensation gradients method improved the SNR of R2* maps in 2D spoiled multi-echo gradient-echo sequences by balancing the compensation gradients and macroscopic field gradients. Compared with the global z-shimming approach, the proposed method provided a broader range of compensated macroscopic field gradients, resulting in higher SNR.
MAGNETIC RESONANCE IN MEDICINE
(2021)
Article
Radiology, Nuclear Medicine & Medical Imaging
Sebastian Dietrich, Christoph S. Aigner, Christoph Kolbitsch, Johannes Mayer, Juliane Ludwig, Simon Schmidt, Tobias Schaeffter, Sebastian Schmitter
Summary: This study introduces and investigates a method for generating homogeneous FA distributions in the human body at ultrahigh field using free-breathing 3D B-1(+) mapping. Experimental validation on healthy subjects and motion phantom demonstrates successful acquisition of 3D B-1(+) maps, showing FA differences in different breathing states.
MAGNETIC RESONANCE IN MEDICINE
(2021)
Article
Biophysics
Christoph Stefan Aigner, Sebastian Dietrich, Sebastian Schmitter
Summary: This study investigates the feasibility of applying 3D flip angle (FA) homogenization targeting the whole heart via static phase-only and dynamic kT-points in parallel transmission at 7T. Results show that 3-4 kT-points achieve a good tradeoff between RF power and nominal FA homogeneity, demonstrating practicality in mitigating FA heterogeneities in the entire 3D heart volume.
NMR IN BIOMEDICINE
(2021)
Article
Radiology, Nuclear Medicine & Medical Imaging
Christoph Stefan Aigner, Sebastian Dietrich, Tobias Schaeffter, Sebastian Schmitter
Summary: The study explores the feasibility of using pre-computed universal pulses for calibration-free homogeneous 3D flip angle distribution in the human heart at 7T. The proposed universal pulse allows for successful calibration-free pTx of the human heart and has the potential to bring body imaging at 7T closer to clinical application.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Layla Tabea Riemann, Christoph Stefan Aigner, Stephen L. R. Ellison, Rudiger Bruehl, Ralf Mekle, Sebastian Schmitter, Oliver Speck, Georg Rose, Bernd Ittermann, Ariane Fillmer
Summary: This study introduced a framework to evaluate the repeatability, reproducibility, and minimal detectable changes of metabolite concentrations determined by in vivo MRS. An unbalanced nested study design and statistical analysis tools were used to acquire data with specific scenarios and assess variance contributions.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Sebastian Dietrich, Christoph Stefan Aigner, Johannes Mayer, Christoph Kolbitsch, Jeanette Schulz-Menger, Tobias Schaeffter, Sebastian Schmitter
Summary: This study demonstrates the feasibility of respiratory motion-compensated 3D cardiac fat-water imaging at 7T. By using self-navigation and model-based reconstruction, high quality images were obtained and respiratory-induced artifacts and flow artifacts were reduced.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Christoph Stefan Aigner, Sebastian Dietrich, Sebastian Schmitter
Summary: Universal and tailored respiration-robust pTx pulses based on RR B1+ maps are preferred for achieving 3D heart FA homogenization at 7T during subjects performing DB, whereas universal and tailored pulses based on NRR B1+ maps are sufficient for subjects performing SB.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Layla Tabea Riemann, Christoph Stefan Aigner, Ralf Mekle, Oliver Speck, Georg Rose, Bernd Ittermann, Sebastian Schmitter, Ariane Fillmer
Summary: The study demonstrated the use of the 2SPECIAL sequence coupled with the novel voxel-GRAPPA decomposition technique to simultaneously acquire spectroscopic signals from two MRS voxels without significant loss in SNR, reducing total scan time by 21.6%. The voxel-GRAPPA algorithm properly reassigned signal components to their respective regions, showing comparable performance to the SENSE-based algorithm in terms of leakage and Cramer-Rao lower bounds for in vivo applications.
MAGNETIC RESONANCE IN MEDICINE
(2022)
Article
Biophysics
Christina Graf, Martin Soellradl, Christoph Stefan Aigner, Armin Rund, Rudolf Stollberger
Summary: This paper proposes a time-optimal control framework for the optimization of Delta B-0(-) and B-1(+)-robust inversion pulses, addressing the robustness requirements in high and ultra-high field MRI systems. The framework, with ensemble formulations and consideration of hardware and energy limitations, performs excellently for various optimization goals and is validated in experiments.
NMR IN BIOMEDICINE
(2022)
Article
Engineering, Biomedical
Simone Hufnagel, Selma Metzner, Kirsten Miriam Kerkering, Christoph Stefan Aigner, Andreas Kofler, Jeanette Schulz-Menger, Tobias Schaeffter, Christoph Kolbitsch
Summary: This study presents a model-based super-resolution reconstruction (SRR) approach for obtaining high-resolution cardiac T1 maps. The approach combines multiple 2D acquisitions to generate 3D T1 maps with higher resolution. The results demonstrate improved visualization of small structures and accurate T1 values.
PHYSICS IN MEDICINE AND BIOLOGY
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Felix Krueger, Christoph Stefan Aigner, Kerstin Hammernik, Sebastian Dietrich, Max Lutz, Jeanette Schulz-Menger, Tobias Schaeffter, Sebastian Schmitter
Summary: This study investigates the feasibility of using deep learning to estimate complex, channel-wise, relative 2D B-1(+)-maps from a single gradient echo localizer to overcome long calibration times. The results show that the deep learning-based B-1(+)-maps match the ground truth for the magnitude and phase, and the technique has the potential to advance clinical body imaging at ultra-high fields.
MAGNETIC RESONANCE IN MEDICINE
(2023)
Article
Neurosciences
Chenyang Zhao, Xingfeng Shao, Qinyang Shou, Samantha J. Ma, Sayim Gokyar, Christina Graf, Rudolf Stollberger, Danny J. J. Wang
Summary: This study presents a distortion-free three-dimensional pCASL sequence at 7T by optimizing labeling parameters, background suppression pulses, and readout sequence. In-vivo experiments demonstrate that this technique achieves whole-cerebrum coverage, high labeling efficiency, and high-resolution imaging without distortion.
Article
Radiology, Nuclear Medicine & Medical Imaging
Bilguun Nurzed, Andre Kuehne, Christoph Stefan Aigner, Sebastian Schmitter, Thoralf Niendorf, Thomas Wilhelm Eigentler
Summary: This study aims to investigate the feasibility of human cardiac MR at 14.0 T using high-density RF dipole transceiver arrays in conjunction with static and dynamic parallel transmission. The results show that both static and dynamic pTx can enhance transmission field uniformity and efficiency at 14.0 T. These findings provide a technical foundation for further exploration into CMR at 14.0 T.
MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Sebastian Dietrich, Christoph S. Aigner, Christoph Kolbitsch, Johannes Mayer, Juliane Ludwig, Simon Schmidt, Tobias Schaeffter, Sebastian Schmitter
Summary: A method for free-breathing three-dimensional B-1(+) mapping of the human body at ultrahigh field (UHF) was introduced and validated in 11 healthy subjects. The method successfully acquired 3D B-1(+) maps free of visible motion artifacts and can be used for investigating and developing 3D B-1(+) shimming and parallel transmission methods.
MAGNETIC RESONANCE IN MEDICINE
(2021)
