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Sembhi R, Ranota T, Fox M, Couch M, Li T, Ball I, Ouriadov A. Feasibility of Dynamic Inhaled Gas MRI-Based Measurements Using Acceleration Combined with the Stretched Exponential Model. Diagnostics (Basel) 2023; 13:diagnostics13030506. [PMID: 36766611 PMCID: PMC9914115 DOI: 10.3390/diagnostics13030506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/22/2023] [Accepted: 01/28/2023] [Indexed: 02/01/2023] Open
Abstract
Dynamic inhaled gas (3He/129Xe/19F) MRI permits the acquisition of regional fractional-ventilation which is useful for detecting gas-trapping in lung-diseases such as lung fibrosis and COPD. Deninger's approach used for analyzing the wash-out data can be substituted with the stretched-exponential-model (SEM) because signal-intensity is attenuated as a function of wash-out-breath in 19F lung imaging. Thirteen normal-rats were studied using 3He/129Xe and 19F MRI and the ventilation measurements were performed using two 3T clinical-scanners. Two Cartesian-sampling-schemes (Fast-Gradient-Recalled-Echo/X-Centric) were used to test the proposed method. The fully sampled dynamic wash-out images were retrospectively under-sampled (acceleration-factors (AF) of 10/14) using a varying-sampling-pattern in the wash-out direction. Mean fractional-ventilation maps using Deninger's and SEM-based approaches were generated. The mean fractional-ventilation-values generated for the fully sampled k-space case using the Deninger method were not significantly different from other fractional-ventilation-values generated for the non-accelerated/accelerated data using both Deninger and SEM methods (p > 0.05 for all cases/gases). We demonstrated the feasibility of the SEM-based approach using retrospective under-sampling, mimicking AF = 10/14 in a small-animal-cohort from the previously reported dynamic-lung studies. A pixel-by-pixel comparison of the Deninger-derived and SEM-derived fractional-ventilation-estimates obtained for AF = 10/14 (≤16% difference) has confirmed that even at AF = 14, the accuracy of the estimates is high enough to consider this method for prospective measurements.
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Affiliation(s)
- Ramanpreet Sembhi
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Tuneesh Ranota
- Faculty of Engineering, School of Biomedical Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Matthew Fox
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
- Lawson Health Research Institute, London, ON N6C 2R5, Canada
| | - Marcus Couch
- Siemens Healthcare Limited, Montreal, QC H4R 2N9, Canada
| | - Tao Li
- Department of Chemistry, Lakehead University, Thunder Bay, ON P7B 5E1, Canada
| | - Iain Ball
- Philips Australia and New Zealand, Sydney 2113, Australia
| | - Alexei Ouriadov
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
- Faculty of Engineering, School of Biomedical Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada
- Lawson Health Research Institute, London, ON N6C 2R5, Canada
- Correspondence:
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Zhu Y, Sappo CR, Grissom WA, Gore JC, Yan X. Dual-Tuned Lattice Balun for Multi-Nuclear MRI and MRS. IEEE TRANSACTIONS ON MEDICAL IMAGING 2022; 41:1420-1430. [PMID: 34990352 PMCID: PMC9812758 DOI: 10.1109/tmi.2022.3140717] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Balun or trap circuits are critical components for suppressing common-mode currents flowing on the outer conductors of coaxial cables in RF coil systems for Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS). Common-mode currents affect coils' tuning and matching, induce losses, pick up extra noise from the surrounding environment, lead to undesired cross-talk, and cause safety concerns in animal and human imaging. First proposed for microwave antenna applications, the Lattice balun has been widely used in MRI coils. It has a small footprint and can be easily integrated with coil tuning/matching circuits. However, the Lattice balun is typically a single-tuned circuit and cannot be used for multi-nuclear MRI and MRS with two RF frequencies. This work describes a dual-tuned Lattice balun design that is suitable for multi-nuclear MRI/MRS. It was first analyzed theoretically to derive component values. RF circuit simulations were then performed to validate the theoretical analysis and provide guidance for practical construction. Based on the simulation results, a dual-tuned balun circuit was built for 7T 1H/23Na MRI and bench tested. The fabricated dual-tuned balun exhibits superior performance at the Larmor frequencies of both 1H and 23Na, with less than 0.15 dB insertion loss and better than 17 dB common-mode rejection ratio at both frequencies.
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Pippard BJ, Neal MA, Maunder AM, Hollingsworth KG, Biancardi A, Lawson RA, Fisher H, Matthews JNS, Simpson AJ, Wild JM, Thelwall PE. Reproducibility of 19 F-MR ventilation imaging in healthy volunteers. Magn Reson Med 2021; 85:3343-3352. [PMID: 33507591 PMCID: PMC7986730 DOI: 10.1002/mrm.28660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/07/2020] [Accepted: 12/07/2020] [Indexed: 01/23/2023]
Abstract
Purpose To assess the reproducibility of percentage ventilated lung volume (%VV) measurements in healthy volunteers acquired by fluorine (19F)‐MRI of inhaled perfluoropropane, implemented at two research sites. Methods In this prospective, ethically approved study, 40 healthy participants were recruited (May 2018‐June 2019) to one of two research sites. Participants underwent a single MRI scan session on a 3T scanner, involving periodic inhalation of a 79% perfluoropropane/21% oxygen gas mixture. Each gas inhalation session lasted about 30 seconds, consisting of three deep breaths of gas followed by a breath‐hold. Four 19F‐MR ventilation images were acquired per participant, each separated by approximately 6 minutes. The value of %VV was determined by registering separately acquired 1H images to ventilation images before semi‐automated image segmentation, performed independently by two observers. Reproducibility of %VV measurements was assessed by components of variance, intraclass correlation coefficients, coefficients of variation (CoV), and the Dice similarity coefficient. Results The MRI scans were well tolerated throughout, with no adverse events. There was a high degree of consistency in %VV measurements for each participant (CoVobserver1 = 0.43%; CoVobserver2 = 0.63%), with overall precision of %VV measurements determined to be within ± 1.7% (95% confidence interval). Interobserver agreement in %VV measurements revealed a high mean Dice similarity coefficient (SD) of 0.97 (0.02), with only minor discrepancies between observers. Conclusion We demonstrate good reproducibility of %VV measurements in a group of healthy participants using 19F‐MRI of inhaled perfluoropropane. Our methods have been successfully implemented across two different study sites, supporting the feasibility of performing larger multicenter clinical studies.
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Affiliation(s)
- Benjamin J. Pippard
- Newcastle Magnetic Resonance CentreNewcastle UniversityNewcastle upon TyneUnited Kingdom
- Translational and Clinical Research InstituteNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Mary A. Neal
- Newcastle Magnetic Resonance CentreNewcastle UniversityNewcastle upon TyneUnited Kingdom
- Translational and Clinical Research InstituteNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Adam M. Maunder
- POLARIS, Department of IICDUniversity of SheffieldRoyal Hallamshire HospitalSheffieldUnited Kingdom
| | - Kieren G. Hollingsworth
- Newcastle Magnetic Resonance CentreNewcastle UniversityNewcastle upon TyneUnited Kingdom
- Translational and Clinical Research InstituteNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Alberto Biancardi
- POLARIS, Department of IICDUniversity of SheffieldRoyal Hallamshire HospitalSheffieldUnited Kingdom
| | - Rod A. Lawson
- Respiratory MedicineSheffield Teaching Hospitals National Health Service Foundation TrustSheffieldUnited Kingdom
| | - Holly Fisher
- Population Health Sciences InstituteNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - John N. S. Matthews
- Population Health Sciences InstituteNewcastle UniversityNewcastle upon TyneUnited Kingdom
- School of Mathematics, Statistics and PhysicsNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - A. John Simpson
- Translational and Clinical Research InstituteNewcastle UniversityNewcastle upon TyneUnited Kingdom
- Respiratory MedicineNewcastle upon Tyne Hospitals National Health Service Foundation TrustNewcastle upon TyneUnited Kingdom
| | - Jim M. Wild
- POLARIS, Department of IICDUniversity of SheffieldRoyal Hallamshire HospitalSheffieldUnited Kingdom
| | - Peter E. Thelwall
- Newcastle Magnetic Resonance CentreNewcastle UniversityNewcastle upon TyneUnited Kingdom
- Translational and Clinical Research InstituteNewcastle UniversityNewcastle upon TyneUnited Kingdom
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Wilcox M, Wright SM, McDougall M. A Review of Non- 1H RF Receive Arrays in Magnetic Resonance Imaging and Spectroscopy. IEEE OPEN JOURNAL OF ENGINEERING IN MEDICINE AND BIOLOGY 2020; 1:290-300. [PMID: 35402958 PMCID: PMC8975242 DOI: 10.1109/ojemb.2020.3030531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 09/15/2020] [Accepted: 09/25/2020] [Indexed: 11/16/2022] Open
Abstract
It is now common practice to use radiofrequency (RF) coils to increase the signal-to-noise ratio (SNR) in 1H magnetic resonance imaging and spectroscopy experiments. Use of array coils for non-1H experiments, however, has been historically more limited despite the fact that these nuclei suffer inherently lower sensitivity and could benefit greatly from an increased SNR. Recent advancements in receiver technology and increased support from scanner manufacturers have now opened greater options for the use of array coils for non-1H magnetic resonance experiments. This paper reviews the research in adopting array coil technology with an emphasis on studies of the most commonly studied non-1H nuclei including 31P, 13C, 23Na, and 19F. These nuclei offer complementary information to 1H imaging and spectroscopy and have proven themselves important in the study of numerous disease processes. While recent work with non-1H array coils has shown promising results, the technology is not yet widely utilized and should see substantial developments in the coming years.
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Choi CH, Hong SM, Felder J, Shah NJ. The state-of-the-art and emerging design approaches of double-tuned RF coils for X-nuclei, brain MR imaging and spectroscopy: A review. Magn Reson Imaging 2020; 72:103-116. [DOI: 10.1016/j.mri.2020.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/16/2020] [Accepted: 07/01/2020] [Indexed: 12/18/2022]
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Maunder A, Chan HF, Hughes PJC, Collier G, Norquay G, Rodgers O, Thelwall P, Robb F, Rao M, Wild JM. MR properties of 19 F C 3 F 8 gas in the lungs of healthy volunteers: T 2 ∗ and apparent diffusion coefficient at 1.5T and T 2 ∗ at 3T. Magn Reson Med 2020; 85:1561-1570. [PMID: 32926448 DOI: 10.1002/mrm.28511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 08/08/2020] [Accepted: 08/17/2020] [Indexed: 01/07/2023]
Abstract
PURPOSE To measure the transverse relaxation time ( T 2 ∗ ) and apparent diffusion coefficient (ADC) of 19 F-C3 F8 gas in vivo in human lungs at 1.5T and 3T, and to determine the representative distribution of values of these parameters in a cohort of healthy volunteers. METHODS Mapping of ADC at lung inflation levels of functional residual capacity (FRC) and total lung capacity (TLC) was performed with inhaled 19 F-C3 F8 (eight subjects) and 129 Xe (six subjects) at 1.5T. T 2 ∗ mapping with 19 F-C3 F8 was performed at 1.5T (at FRC and TLC) for 8 subjects and at 3T (at TLC for seven subjects). RESULTS At both FRC and TLC, the 19 F-C3 F8 ADC was smaller than the free diffusion coefficient demonstrating airway microstructural diffusion restriction. From FRC to TLC, the mean ADC significantly increased from 1.56 mm2 /s to 1.83 mm2 /s (P = .0017) for 19 F-C3 F8, and from 2.49 mm2 /s to 3.38 mm2 /s (P = .0015) for 129 Xe. The posterior-to-anterior gradient in ADC for FRC versus TLC in the superior half of the lungs was measured as 0.0308 mm2 /s per cm versus 0.0168 mm2 /s per cm for 19 F-C3 F8 and 0.0871 mm2 /s per cm versus 0.0326 mm2 /s per cm for 129 Xe. A consistent distribution of 19 F-C3 F8 T 2 ∗ values was observed in the lungs, with low values observed near the diaphragm and large pulmonary vessels. The mean T 2 ∗ across volunteers was 4.48 ms at FRC and 5.33 ms at TLC for 1.5T, and 3.78 ms at TLC for 3T. CONCLUSION In this feasibility study, values of physiologically relevant parameters of lung microstructure measurable by MRI ( T 2 ∗ , and ADC) were established for C3 F8 in vivo lung imaging in healthy volunteers.
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Affiliation(s)
- Adam Maunder
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Ho-Fung Chan
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Paul J C Hughes
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Guillhem Collier
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Graham Norquay
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Oliver Rodgers
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Peter Thelwall
- Newcastle Magnetic Resonance Centre, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Fraser Robb
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom.,GE Healthcare, Aurora, Ohio, USA
| | - Madhwesha Rao
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
| | - Jim M Wild
- POLARIS, Imaging Group, Department of IICD, University of Sheffield, Sheffield, United Kingdom
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