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Foongkajornkiat S, Sokolowski K, Stephenson J, Lloyd T, Hugo HJ, Thompson EW, Momot KI. Quantitative measurement of mammographic density in breast-tissue explants using portable NMR: Precision and accuracy. Magn Reson Med 2024; 92:374-388. [PMID: 38380719 DOI: 10.1002/mrm.30040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 12/20/2023] [Accepted: 01/18/2024] [Indexed: 02/22/2024]
Abstract
PURPOSE Single-sided portable NMR (pNMR) has previously been demonstrated to be suitable for quantification of mammographic density (MD) in excised breast tissue samples. Here we investigate the precision and accuracy of pNMR measurements of MD ex vivo as compared with the gold standards. METHODS Forty-five breast-tissue explants from 9 prophylactic mastectomy patients were measured. The relative tissue water content was taken as the MD-equivalent quantity. In each sample, the water content was measured using some combination of three pNMR techniques (apparent T2, diffusion, and T1 measurements) and two gold-standard techniques (computed microtomography [μCT] and hematoxylin and eosin [H&E] histology). Pairwise correlation plots and Bland-Altman analysis were used to quantify the degree of agreement between pNMR techniques and the gold standards. RESULTS Relative water content measured from both apparent T2 relaxation spectra, and diffusion decays exhibited strong correlation with the H&E and μCT results. Bland-Altman analysis yielded average bias values of -0.4, -2.6, 2.6, and 2.8 water percentage points (pp) and 95% confidence intervals of 13.1, 7.5, 11.2, and 11.8 pp for the H&E - T2, μCT - T2, H&E - diffusion, and μCT - diffusion comparison pairs, respectively. T1-based measurements were found to be less reliable, with the Bland-Altman confidence intervals of 27.7 and 33.0 pp when compared with H&E and μCT, respectively. CONCLUSION Apparent T2-based and diffusion-based pNMR measurements enable quantification of MD in breast-tissue explants with the precision of approximately 10 pp and accuracy of approximately 3 pp or better, making pNMR a promising measurement modality for radiation-free quantification of MD.
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Affiliation(s)
- Satcha Foongkajornkiat
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Kamil Sokolowski
- Preclincal Imaging Facility, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - James Stephenson
- Department of Breast and Endocrine Surgery, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
- Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Thomas Lloyd
- Department of Diagnostic Radiology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Honor J Hugo
- School of Health and Behavioural Science, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
- School of Medicine and Dentistry, Griffith University Sunshine Coast, Birtinya, Queensland, Australia
| | - Erik W Thompson
- Translational Research Institute, Woolloongabba, Queensland, Australia
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Konstantin I Momot
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, Queensland, Australia
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2
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Javor J, Yao Z, Barrett L, Imboden M, Apte S, Giannetta RW, Campbell DK, Bishop DJ. Modal engineering of electromagnetic circuits to achieve rapid settling times. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:014708. [PMID: 36725583 DOI: 10.1063/5.0125097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/28/2022] [Indexed: 06/18/2023]
Abstract
Inductive circuits and devices are ubiquitous and important design elements in many applications, such as magnetic drives, galvanometers, magnetic scanners, applying direct current (DC) magnetic fields to systems, radio frequency coils in nuclear magnetic resonance (NMR) systems, and a vast array of other applications. They are widely used to generate both DC and alternating current (AC) magnetic fields. Many of these applications require a rapid step and settling time, turning the DC or AC magnetic field on and off quickly. The inductive response normally makes this a challenging thing to do. In this article, we discuss open loop control algorithms for achieving rapid step and settling times in four general categories of applications: DC and AC systems where the system is either under- or over-damped. Each of these four categories requires a different algorithm, which we describe here. We show the operation of these drive methods using Simulink and Simscape modeling tools, analytical solutions to the underlying differential equations, and experimental results using an inductive magnetic coil and a Hall sensor. Finally, we demonstrate the application of these techniques to significantly reduce ringing in a standard NMR circuit. We intend this article to be practical, with useful, easy-to-apply algorithms and helpful tuning tricks.
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Affiliation(s)
- Josh Javor
- Mechanical Engineering Department, Boston University, Boston, Massachusetts 02215, USA
| | - Zhancheng Yao
- Division of Material Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Lawrence Barrett
- Division of Material Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Matthias Imboden
- STI-IMT LMTS, École Polytechnique Fédérale de Lausanne, Neuchâtel 2000, Switzerland
| | - Sohm Apte
- Department of Physics, University of Texas, Austin, Texas 78712, USA
| | - Russel W Giannetta
- Department of Physics, University of Illonois, Champaign, Illonois 61820, USA
| | - David K Campbell
- Department of Physics, Boston University, Boston, Massachusetts 02215, USA
| | - David J Bishop
- Mechanical Engineering Department, Boston University, Boston, Massachusetts 02215, USA
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3
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Morin DM, Lawrence M, Balcom BJ. Design and validation of a single-sided magnet with a constant gradient parallel to its surface. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 342:107266. [PMID: 35905531 DOI: 10.1016/j.jmr.2022.107266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 06/15/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
We present the design, validation, and testing of an optimized 5 MHz three-magnet array with a gradient parallel to the magnet surface. An approach to permanent magnet array design is explored with a genetic algorithm. The genetic algorithm was used to produce multiple designs based on an inventory of available block magnets. One three-magnet array was constructed for testing. Constant gradients of 205, 115, and 61 gauss/cm, parallel to the magnet surface are found at displacements of 1.5, 2.0, and 2.5 cm from the surface of the magnet, respectively. Regions of useful gradient are roughly 1 cm in length. We constructed and field plotted the three-magnet array and found good agreement between the experimental and simulated magnet fields. To test applicability, we performed T1 and T2 relaxation measurements on a cod liver oil sample, and a simple doped water flow measurement.
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Affiliation(s)
- Devin M Morin
- UNB MRI Centre, Department of Physics, University of New Brunswick, Fredericton E3B 5A3, Canada
| | - Maggie Lawrence
- UNB MRI Centre, Department of Physics, University of New Brunswick, Fredericton E3B 5A3, Canada
| | - Bruce J Balcom
- UNB MRI Centre, Department of Physics, University of New Brunswick, Fredericton E3B 5A3, Canada.
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4
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Tewari S, Yousefi S, Webb A. Deep neural-network based optimization for the design of a multi-element surface magnet for MRI applications. INVERSE PROBLEMS 2022; 38:035003. [PMID: 36046464 PMCID: PMC7613466 DOI: 10.1088/1361-6420/ac492a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We present a combination of a CNN-based encoder with an analytical forward map for solving inverse problems. We call it an encoder-analytic (EA) hybrid model. It does not require a dedicated training dataset and can train itself from the connected forward map in a direct learning fashion. A separate regularization term is not required either, since the forward map also acts as a regularizer. As it is not a generalization model it does not suffer from overfitting. We further show that the model can be customized to either find a specific target solution or one that follows a given heuristic. As an example, we apply this approach to the design of a multi-element surface magnet for low-field magnetic resonance imaging (MRI). We further show that the EA model can outperform the benchmark genetic algorithm model currently used for magnet design in MRI, obtaining almost 10 times better results.
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Affiliation(s)
- Sumit Tewari
- C.J. Gorter Center for High Field MRI, Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Sahar Yousefi
- Division of Image Processing, Leiden University Medical Center, Leiden, The Netherlands
| | - Andrew Webb
- C.J. Gorter Center for High Field MRI, Radiology, Leiden University Medical Center, Leiden, The Netherlands
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5
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Wang Y, Xu Y, Zhang M, Emmanuel Komolafe T, Wang W, Luo H, Chen X, Yang X, Wu Z. A single-sided magnet for deep-depth fat quantification. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 331:107053. [PMID: 34428727 DOI: 10.1016/j.jmr.2021.107053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 06/06/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Early detection of fatty-liver disease is important before further aggravations of the disease, such as cirrhosis, can develop. In this study, we developed a low-cost, movable single-sided magnet for in vivo liver fat quantification. A gradient field of 73.5 G/cm and a field strength of 0.0725 T were obtained by structurally optimizing the concave U-shaped magnet, on which the region of interest (ROI) was a curved shape about 0.4 mm thick, 8 cm above the surface of the radiofrequency (RF) coil. We constructed a prototype nuclear magnetic-resonance (NMR) relaxometry system based on this optimized magnet. Subsequent phantom experiments demonstrated the effectiveness of the single-sided magnet in evaluating different proton density fat fraction (PDFF) phantoms. As expected, the results of the six phantoms showed good positive correlation between PDFF and the fitted fat amplitude, which suggested that single-sided NMR relaxometry could be used to quantify liver fat in vivo.
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Affiliation(s)
- Ya Wang
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, Jiangsu, China; School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Yajie Xu
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, Jiangsu, China
| | - Mingkang Zhang
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, Jiangsu, China; School of Electronic and Information Engineering, Changchun University of Science and Technology, 130022, Changchun, China
| | - Temitope Emmanuel Komolafe
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, Jiangsu, China; School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Weiqian Wang
- Wuxi Marvel Stone Healthcare Co. Ltd., Wuxi 214135, Jiangsu, China
| | - Hai Luo
- Wuxi Marvel Stone Healthcare Co. Ltd., Wuxi 214135, Jiangsu, China
| | - Xiao Chen
- Wuxi Marvel Stone Healthcare Co. Ltd., Wuxi 214135, Jiangsu, China
| | - Xiaodong Yang
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, Jiangsu, China.
| | - Ziyue Wu
- Wuxi Marvel Stone Healthcare Co. Ltd., Wuxi 214135, Jiangsu, China.
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6
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Rudszuck T, Nirschl H, Guthausen G. Perspectives in process analytics using low field NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 323:106897. [PMID: 33518174 DOI: 10.1016/j.jmr.2020.106897] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 12/15/2020] [Accepted: 12/18/2020] [Indexed: 06/12/2023]
Abstract
Low field NMR is a powerful analytical tool which creates an enormous added value in process analytics. Based on specific applications in process analytics and perspectives for low field NMR in form of spectroscopy, relaxation, diffusion, and imaging in quality control, diverse applications and technical realizations like spectrometers, time domain NMR, mobile NMR sensors and MRI will be discussed.
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Affiliation(s)
- T Rudszuck
- Institute for Mechanical Engineering and Mechanics, KIT, 76131 Karlsruhe, Germany
| | - H Nirschl
- Institute for Mechanical Engineering and Mechanics, KIT, 76131 Karlsruhe, Germany
| | - G Guthausen
- Institute for Mechanical Engineering and Mechanics, KIT, 76131 Karlsruhe, Germany; Engler-Bunte Institut, Water Science and Technology, KIT, 76131 Karlsruhe, Germany
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7
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Bashyam A, Frangieh CJ, Raigani S, Sogo J, Bronson RT, Uygun K, Yeh H, Ausiello DA, Cima MJ. A portable single-sided magnetic-resonance sensor for the grading of liver steatosis and fibrosis. Nat Biomed Eng 2020; 5:240-251. [PMID: 33257853 DOI: 10.1038/s41551-020-00638-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 09/28/2020] [Indexed: 12/19/2022]
Abstract
Low-cost non-invasive diagnostic tools for staging the progression of non-alcoholic chronic liver failure from fatty liver disease to steatohepatitis are unavailable. Here, we describe the development and performance of a portable single-sided magnetic-resonance sensor for grading liver steatosis and fibrosis using diffusion-weighted multicomponent T2 relaxometry. In a diet-induced mouse model of non-alcoholic fatty liver disease, the sensor achieved overall accuracies of 92% (Cohen's kappa, κ = 0.89) and 86% (κ = 0.78) in the ex vivo grading of steatosis and fibrosis, respectively. Localization of the measurements in living mice through frequency-dependent spatial encoding led to an overall accuracy of 87% (κ = 0.81) for the grading of steatosis. In human liver samples, the sensor graded steatosis with an overall accuracy of 93% (κ = 0.88). The use of T2 relaxometry as a sensitive measure in fully automated low-cost magnetic-resonance devices at the point of care would alleviate the accessibility and cost limits of magnetic-resonance imaging for diagnosing liver disease and assessing liver health before liver transplantation.
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Affiliation(s)
- Ashvin Bashyam
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Electrical Engineering & Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Chris J Frangieh
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Electrical Engineering & Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Siavash Raigani
- Division of Transplantation, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
| | - Jeremy Sogo
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Electrical Engineering & Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Roderick T Bronson
- Department of Microbiology and Immunobiology, Division of Immunology, Harvard Medical School, Boston, MA, USA
| | - Korkut Uygun
- Center for Engineering in Medicine and Surgery, Massachusetts General Hospital, Boston, MA, USA
| | - Heidi Yeh
- Division of Transplantation, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
| | - Dennis A Ausiello
- Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA.,Center for Assessment Technology and Continuous Health, Massachusetts General Hospital, Boston, MA, USA
| | - Michael J Cima
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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8
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Bashyam A, Li M, Cima MJ. Design and experimental validation of Unilateral Linear Halbach magnet arrays for single-sided magnetic resonance. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 292:36-43. [PMID: 29763794 DOI: 10.1016/j.jmr.2018.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 06/08/2023]
Abstract
Single-sided NMR has the potential for broad utility and has found applications in healthcare, materials analysis, food quality assurance, and the oil and gas industry. These sensors require a remote, strong, uniform magnetic field to perform high sensitivity measurements. We demonstrate a new permanent magnet geometry, the Unilateral Linear Halbach, that combines design principles from "sweet-spot" and linear Halbach magnets to achieve this goal through more efficient use of magnetic flux. We perform sensitivity analysis using numerical simulations to produce a framework for Unilateral Linear Halbach design and assess tradeoffs between design parameters. Additionally, the use of hundreds of small, discrete magnets within the assembly allows for a tunable design, improved robustness to variability in magnetization strength, and increased safety during construction. Experimental validation using a prototype magnet shows close agreement with the simulated magnetic field. The Unilateral Linear Halbach magnet increases the sensitivity, portability, and versatility of single-sided NMR.
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Affiliation(s)
- Ashvin Bashyam
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, United States; Electrical Engineering & Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, United States.
| | - Matthew Li
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, United States; Harvard-MIT Program of Health Sciences and Technology, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, United States.
| | - Michael J Cima
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, United States; Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, United States.
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9
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Tahayori B, Johnston LA, Layton KJ, Farrell PM, Mareels IMY. Solving the Bloch equation with periodic excitation using harmonic balancing: application to Rabi modulated excitation. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:2118-2130. [PMID: 25879910 DOI: 10.1109/tmi.2015.2423313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In waveform design for magnetic resonance applications, periodic continuous-wave excitation offers potential advantages that remain largely unexplored because of a lack of understanding of the Bloch equation with periodic continuous-wave excitations. Using harmonic balancing techniques the steady state solutions of the Bloch equation with periodic excitation can be effectively solved. Moreover, the convergence speed of the proposed series approximation is such that a few terms in the series expansion suffice to obtain a very accurate description of the steady state solution. The accuracy of the proposed analytic approximate series solution is verified using both a simulation study as well as experimental data derived from a spherical phantom with doped water under continuous-wave excitation. Typically a five term series suffices to achieve a relative error of less than one percent, allowing for a very effective and efficient analytical design process. The opportunities for Rabi frequency modulated continuous-wave form excitation are then explored, based on a comparison with steady state free precession pulse sequences.
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