scholarly journals High-Field Pulsed ENDOR with Intra-cavity Radiofrequency Coil

2020 ◽  
Vol 51 (11) ◽  
pp. 1433-1449
Author(s):  
G. Annino ◽  
H. Moons ◽  
M. Fittipaldi ◽  
S. Van Doorslaer ◽  
E. Goovaerts
Keyword(s):  
Magnetic Field ◽  
High Field ◽  
Conversion Factor ◽  
Signal To Noise Ratio ◽  
Model Systems ◽  
Signal To Noise ◽  
Radiofrequency Coil ◽  
W Band ◽  
Radiofrequency Current ◽  
Field Uniformity

AbstractThis study compares the performance of two coil configurations for W-band pulsed ENDOR using a setup with both a radiofrequency ‘hairpin’ coil internal to a microwave non-radiative resonator and Helmholtz-like coils external to the resonator. Evaluation of the different coil performances is achieved via the ENDOR study of two model systems. The efficiencies of the coil configurations are first investigated numerically, showing that a higher radiofrequency current-to-magnetic field conversion factor can be achieved with the intra-cavity coil, with a similar radiofrequency magnetic field uniformity. This result is then confirmed by the broadband ENDOR spectra acquired with the two coil arrangements. A gain in the signal-to-noise ratio enabled by the internal coil of about a factor 10 was observed. In some cases, the high conversion factor of the intra-cavity coil led to a saturation of the ENDOR transitions. The possibility to implement a similar intra-cavity radiofrequency coil configuration in higher field spectrometers is finally discussed.

scholarly journals Effect of radiofrequency shield diameter on signal‐to‐noise ratio at ultra‐high field MRI

2021 ◽  
Vol 85 (6) ◽  
pp. 3522-3530
Author(s):  
Bei Zhang ◽  
Gregor Adriany ◽  
Lance Delabarre ◽  
Jerahmie Radder ◽  
Russell Lagore ◽  
...  
Keyword(s):  
High Field ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Ultra High Field ◽  
High Field Mri ◽  
Ultra High Field Mri ◽  
Noise Ratio

scholarly journals Signal-to-noise ratio, T2 , and T2* for hyperpolarized helium-3 MRI of the human lung at three magnetic field strengths

2016 ◽  
Vol 78 (4) ◽  
pp. 1458-1463 ◽  
Author(s):  
Peter Komlosi ◽  
Talissa A. Altes ◽  
Kun Qing ◽  
Karen E. Mooney ◽  
G. Wilson Miller ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Human Lung ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Hyperpolarized Helium ◽  
Helium 3 ◽  
Noise Ratio ◽  
Field Strengths

scholarly journals Design and Research of Inductive Oil Pollutant Detection Sensor Based on High Gradient Magnetic Field Structure

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 638
Author(s):  
Wei Li ◽  
Chenzhao Bai ◽  
Chengjie Wang ◽  
Hongpeng Zhang ◽  
Lebile Ilerioluwa ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Signal To Noise Ratio ◽  
Detection Accuracy ◽  
Iron Particles ◽  
Signal To Noise ◽  
Gradient Magnetic Field ◽  
High Gradient ◽  
Copper Particles ◽  
Pollutant Detection ◽  
Noise Ratio

An inductive oil pollutant detection sensor based on a high-gradient magnetic field structure is designed in this paper, which is mainly used for online detection and fault analysis of pollutants in hydraulic and lubricating oil systems. The innovation of the sensor is based on the inductance detection method. Permalloy is embedded in the sensing region of the sensor, so that the detection area generates a high gradient magnetic field to enhance the detection accuracy of the sensor. Compared with traditional inductive sensors, the sensor has a significant improvement in detection accuracy, and the addition of permalloy greatly improves the stability of the sensor’s detection unit structure. The article theoretically analyzes the working principle of the sensor, optimizes the design parameters and structure of the sensor through simulation, determines the best permalloy parameters, and establishes an experimental system for verification. Experimental results show that when a piece of permalloy is added to the sensing unit, the signal-to-noise ratio (SNR) of iron particles is increased by more than 20%, and the signal-to-noise ratio of copper particles is increased by more than 70%. When two pieces of permalloy are added, the signal-to-noise ratio for iron particles is increased by more than 70%, and the SNR for copper particles is increased several times. This method raises the lower limit of detection for ferromagnetic metal particles to 20 μm, and the lower limit for detection of non-ferromagnetic metal particles to 80 μm, which is the higher detection accuracy of the planar coil sensors. This paper provides a new and faster online method for pollutant detection in oil, which is of great significance for diagnosing and monitoring the health of oil in mechanical systems.

scholarly journals Improving Signal to Noise Ratio in Ultra High Field Magnetic Resonance Imaging

2021 ◽  
Author(s):  
Nader Tavaf
Keyword(s):  
Human Brain ◽  
High Field ◽  
Signal To Noise Ratio ◽  
Noise Correlation ◽  
Resonance Imaging ◽  
Mr Images ◽  
Signal To Noise ◽  
Ultra High Field ◽  
Noise Ratio ◽  
Receive Array

Ultra-High Field (UHF) Magnetic Resonance Imaging (MRI) advantages, including higher image resolution, reduced acquisition time via parallel imaging, and better signal-to-noise ratio (SNR) have opened new opportunities for various clinical and research projects, including functional MRI, brain connectivity mapping, and anatomical imaging. The advancement of these UHF MRI performance metrics, especially SNR, was the primary motivation of this thesis. Unaccelerated SNR depends on receive array sensitivity profile, receiver noise correlation and static magnetic field strength. Various receive array decoupling technologies, including overlap/inductive and preamplifier decoupling, were previously utilized to mitigate noise correlation. In this dissertation, I developed a novel self-decoupling principle to isolate elements of a loop-based receive array and demonstrated, via full-wave electromagnetic/circuit co-simulations validated by bench measurements, that the self-decoupling technique provides inter-element isolation on par with overlap decoupling while self-decoupling improves SNR. I then designed and constructed the first self-decoupled 32 and 64 channel receiver arrays for human brain MR imaging at 10.5T / 447MHz. Experimental comparisons of these receive arrays with the industry’s gold-standard 7T 32 channel receiver resulted in 1.81 times and 3.53 times more average SNR using the 10.5T 32 and 64 channel receivers I built, respectively. To further improve the SNR of accelerated MR images, I developed a novel data-driven model using a customized conditional generative adversarial network (GAN) architecture for parallel MR image reconstruction and demonstrated that, when applied to human brain images subsampled with rate of 4, the GAN model results in a peak signal-to-noise ratio (PSNR) of 37.65 compared to GeneRalized Autocalibrating Partial Parallel Acquisition (GRAPPA)’s PSNR of 33.88.In summary, the works presented in this dissertation improved the SNR available for human brain imaging and provided the experimental realization of the advantages anticipated at 10.5T MRI. The insights from this thesis inform future efforts to build self-decoupled transmit arrays and high density, 128 channel loop-based receive arrays for human brain MRI especially at ultra-high field as well as future studies to utilize deep learning techniques for reconstruction and post-processing of parallel MR images.

scholarly journals Risonanza Magnetica della Mammella con i moderni scanner 3T: principi fisici e vantaggi tecnici rispetto alle apparecchiature 1,5 T

2019 ◽  
Author(s):  
Curatolo Calogero ◽  
Santoro Vincenzo
Keyword(s):  
Magnetic Field ◽  
Magnetic Resonance ◽  
Breast Imaging ◽  
High Field ◽  
Signal To Noise Ratio ◽  
Risonanza Magnetica ◽  
3 Tesla ◽  
Magnetic Resonance Imaging Mri ◽  
Mri Study ◽  
Very High

In recent decades the Magnetic Resonance Imaging (MRI) world, for diagnostic uses, offered a very rapid and extremely dynamic and necessary technological evolution. Recently approved in Italy also for clinical use, in addition to the scientific one, the introduction of very high-field MRI, or 3 Tesla, provided considerable benefits. Therefore, the high magnetic field (3T) allows an increase in the signal-to-noise ratio (SNR) and in spatial and temporal resolution, and other several advantages. Certainly, there are some disadvantages, which can be found in the field of protectionism and safety, due to the increase in intensity of the static magnetic field and, specifically, to the increase in Specific Absorption Rate (SAR). Many applications of MRI improved significantly, among these, the brest MRI study, where the 3T magnetic field allows an increase of diagnostic accuracy in terms of specificity, providing a better visualization and characterization of breast lesions presenting post-contrastographic enhancement, so breast cancer and other lesions, showing a progressive better application field. Magnetic resonance is an emerging application with great potential, and the spread of very high-field scanners will allow 3 Tesla to become the excellence for many studies, especially in breast imaging.

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