scholarly journals Topologically optimized magnetic lens for magnetic resonance applications

2020 ◽  
Vol 1 (2) ◽  
pp. 225-236
Author(s):  
Sagar Wadhwa ◽  
Mazin Jouda ◽  
Yongbo Deng ◽  
Omar Nassar ◽  
Dario Mager ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Numerical Optimization ◽  
Signal To Noise Ratio ◽  
Optimal Layout ◽  
Magnetic Lens ◽  
Resonator Design ◽  
Sample Shape ◽  
Field Homogeneity ◽  
Design Requirements ◽  
Resonance Detection

Abstract. Improvements to the signal-to-noise ratio of magnetic resonance detection lead to a strong reduction in measurement time, yet as a sole optimization goal for resonator design, it would be an oversimplification of the problem at hand. Multiple constraints, for example for field homogeneity and sample shape, suggest the use of numerical optimization to obtain resonator designs that deliver the intended improvement. Here we consider the 2D Lenz lens to be a sufficiently broadband flux transforming interposer between the sample and a radiofrequency (RF) circuit and to be a flexible and easily manufacturable device family with which to mediate different design requirements. We report on a method to apply topology optimization to determine the optimal layout of a Lenz lens and demonstrate realizations for both low- (45 MHz) and high-frequency (500 MHz) nuclear magnetic resonance.

scholarly journals Topologically Optimized Magnetic Lens for MR Applications

2020 ◽  
Author(s):  
Sagar Wadhwa ◽  
Mazin Jouda ◽  
Yongbo Deng ◽  
Omar Nassar ◽  
Dario Mager ◽  
...  
Keyword(s):  
Numerical Optimization ◽  
Signal To Noise Ratio ◽  
Broad Band ◽  
Optimal Layout ◽  
Magnetic Lens ◽  
Resonator Design ◽  
Sample Shape ◽  
Field Homogeneity ◽  
Design Requirements ◽  
Resonance Detection

Abstract. Improvements to the signal-to-noise ratio of magnetic resonance detection leads to a strong reduction in measurement time, yet as a sole optimization goal for resonator design it would be an oversimplification of the problem at hand. Multiple constraints, for example for field homogeneity, and sample shape, suggests the use of numerical optimization to obtain resonator designs that delivers the intended improvement. Here we consider the 2D Lenz lens as a sufficiently broad-band flux transforming interposer between the sample and an RF circuit, as a flexible and an easily manufacturable device family with which to mediate different design requirements. We report on a method to apply topology optimization to determine the optimal layout of a Lenz lens, and demonstrate realisations for both low (45 MHz), and high frequency (500 MHz) NMR.

scholarly journals Cardiac Magnetic Resonance Detection of Myocardial Scarring in Hypertrophic Cardiomyopathy

2009 ◽  
Vol 54 (3) ◽  
pp. 242-249 ◽  
Author(s):  
Deborah H. Kwon ◽  
Nicholas G. Smedira ◽  
E. Rene Rodriguez ◽  
Carmela Tan ◽  
Randolph Setser ◽  
...  
Keyword(s):  
Cardiac Magnetic Resonance ◽  
Hypertrophic Cardiomyopathy ◽  
Magnetic Resonance ◽  
Myocardial Scarring ◽  
Resonance Detection

The Clifford Paterson Lecture, 1993, Accurate measurement in in vivo magnetic Resonance: an engineering problem?

1994 ◽  
Vol 349 (1691) ◽  
pp. 357-388
Keyword(s):  
Magnetic Resonance ◽  
Signal To Noise Ratio ◽  
Engineering Problem ◽  
Resonance Imaging ◽  
Significant Extent ◽  
Performance System ◽  
Imaging And Spectroscopy ◽  
Intractable Problem ◽  
Conceptual Difficulties

Measurement in in vivo magnetic resonance — both in imaging and spectroscopy — has proved to be a much more intractable problem than extrapolation from conventional high resolution studies might have suggested. Although this paper concentrates mainly on some of the complications of magnetic resonance imaging, the same conceptual difficulties (compounded by much reduced signal levels) affect in vivo spectroscopy. Tissue is an extremely complex system and many of the difficulties studying it arise from the interactions that are unintentionally engendered when it is observed. Patient motion is a potent source of artifact to the technical challenge of making better measurements, and different forms of motion are likely to be the ultimate limitation on the sensitivity and discrimination of the technique as a whole. In this context it is observed that the traditional criterion of performance — system signal-to-noise ratio — should be replaced by a signal-to-artifact estimate, and that this may affect the design and implementation of detector systems to a significant extent.

Nuclear Magnetic Resonance Detection of Two Distinctly Different Chains in the Orthorhombic Crystalline Phase of Polyethylenes†

1998 ◽  
Vol 31 (15) ◽  
pp. 5010-5021 ◽  
Author(s):  
Luminita Hillebrand ◽  
Angelika Schmidt ◽  
Andreas Bolz ◽  
Michael Hess ◽  
Wiebren Veeman ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Crystalline Phase ◽  
Resonance Detection ◽  
Nuclear Magnetic

scholarly journals Performance of compressed sensing for fluorine‐19 magnetic resonance imaging at low signal‐to‐noise ratio conditions

2019 ◽  
Vol 84 (2) ◽  
pp. 592-608
Author(s):  
Ludger Starke ◽  
Andreas Pohlmann ◽  
Christian Prinz ◽  
Thoralf Niendorf ◽  
Sonia Waiczies
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Compressed Sensing ◽  
Signal To Noise Ratio ◽  
Resonance Imaging ◽  
Signal To Noise ◽  
Noise Ratio

scholarly journals Magnetic Resonance Image Denoising Algorithm Based on Cartoon, Texture, and Residual Parts

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yanqiu Zeng ◽  
Baocan Zhang ◽  
Wei Zhao ◽  
Shixiao Xiao ◽  
Guokai Zhang ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Gaussian Noise ◽  
Signal To Noise Ratio ◽  
Wiener Filter ◽  
Electronic Noise ◽  
Mr Images ◽  
Electronic Components ◽  
Mr Image ◽  
Residual Part ◽  
Soft Threshold

Magnetic resonance (MR) images are often contaminated by Gaussian noise, an electronic noise caused by the random thermal motion of electronic components, which reduces the quality and reliability of the images. This paper puts forward a hybrid denoising algorithm for MR images based on two sparsely represented morphological components and one residual part. To begin with, decompose a noisy MR image into the cartoon, texture, and residual parts by MCA, and then each part is denoised by using Wiener filter, wavelet hard threshold, and wavelet soft threshold, respectively. Finally, stack up all the denoised subimages to obtain the denoised MR image. The experimental results show that the proposed method has significantly better performance in terms of mean square error and peak signal-to-noise ratio than each method alone.

Low Field Magnetic Resonance Imaging of Focal Hepatic Masses at 0.02 T

1989 ◽  
Vol 30 (6) ◽  
pp. 591-595
Author(s):  
L. Ekelund ◽  
L. Athlin
Keyword(s):  
Magnetic Resonance ◽  
Mr Imaging ◽  
Malignant Tumors ◽  
Signal To Noise Ratio ◽  
Malignant Neoplasms ◽  
Hepatic Hemangioma ◽  
Resonance Imaging ◽  
Benign Lesions ◽  
Low Field ◽  
Better Than

The diagnostic utility of extremely low field magnetic resonance (MR) imaging was evaluated in 25 patients with focal hepatic masses, including 17 with primary (n=7) or secondary (n= 10) malignant neoplasms and 8 with benign lesions (6 hemangiomas). The findings were compared with the results of computed tomography (CT). Out of 16 patients with malignant tumors demonstrated by both modalities, the diagnostic information from MR imaging was equal to or better than that from CT in 6 patients and inferior to CT in 10. Shortcomings of MR were mainly due to low signal-to-noise ratio and poor spatial resolution, resulting in an image quality inferior to that obtained at higher field strengths. Considering these facts, together with the long imaging times required, low field MR cannot be recommended for general use in the evaluation of hepatic masses. On the other hand, our results indicate that this technique may be useful in establishing the diagnosis of hepatic hemangioma.

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