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Reichert S, Schepkin V, Kleimaier D, Zöllner FG, Schad LR. Sodium triple quantum MR signal extraction using a single-pulse sequence with single quantum time efficiency. Magn Reson Med 2024; 92:900-915. [PMID: 38650306 DOI: 10.1002/mrm.30107] [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: 11/07/2023] [Revised: 02/25/2024] [Accepted: 03/20/2024] [Indexed: 04/25/2024]
Abstract
PURPOSE Sodium triple quantum (TQ) signal has been shown to be a valuable biomarker for cell viability. Despite its clinical potential, application of Sodium TQ signal is hindered by complex pulse sequences with long scan times. This study proposes a method to approximate the TQ signal using a single excitation pulse without phase cycling. METHODS The proposed method is based on a single excitation pulse and a comparison of the free induction decay (FID) with the integral of the FID combined with a shifting reconstruction window. The TQ signal is calculated from this FID only. As a proof of concept, the method was also combined with a multi-echo UTE imaging sequence on a 9.4 T preclinical MRI scanner for the possibility of fast TQ MRI. RESULTS The extracted Sodium TQ signals of single-pulse and spin echo FIDs were in close agreement with theory and TQ measurement by traditional three-pulse sequence (TQ time proportional phase increment [TQTPPI)]. For 2%, 4%, and 6% agar samples, the absolute deviations of the maximum TQ signals between SE and theoretical (time proportional phase increment TQTPPI) TQ signals were less than 1.2% (2.4%), and relative deviations were less than 4.6% (6.8%). The impact of multi-compartment systems and noise on the accuracy of the TQ signal was small for simulated data. The systematic error was <3.4% for a single quantum (SQ) SNR of 5 and at maximum <2.5% for a multi-compartment system. The method also showed the potential of fast in vivo SQ and TQ imaging. CONCLUSION Simultaneous SQ and TQ MRI using only a single-pulse sequence and SQ time efficiency has been demonstrated. This may leverage the full potential of the Sodium TQ signal in clinical applications.
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Affiliation(s)
- Simon Reichert
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Cooperative Core Facility Animal Scanner ZI, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Victor Schepkin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA
| | - Dennis Kleimaier
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank G Zöllner
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Cooperative Core Facility Animal Scanner ZI, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Lothar R Schad
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Reichert S, Schepkin V, Kleimaier D, Zöllner FG, Schad LR. Comparison of triple quantum (TQ) TPPI and inversion recovery TQ TPPI pulse sequences at 9.4 and 21.1 T. NMR IN BIOMEDICINE 2024; 37:e5106. [PMID: 38263738 DOI: 10.1002/nbm.5106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/04/2023] [Accepted: 12/27/2023] [Indexed: 01/25/2024]
Abstract
PURPOSE Both sodium T1 triple quantum (TQ) signal and T1 relaxation pathways have a unique sensitivity to the sodium molecular environment. In this study an inversion recovery time proportional phase increment (IRTQTPPI) pulse sequence was investigated for simultaneous and reliable quantification of sodium TQ signal and bi-exponential T1 relaxation times. METHODS The IRTQTPPI sequence combines inversion recovery TQ filtering and time proportional phase increment. The reliable and reproducible results were achieved by the pulse sequence optimized in three ways: (1) optimization of the nonlinear fit for the determination of both T1-TQ signal and T1 relaxation times; (2) suppression of unwanted signals by assessment of four different phase cycles; (3) nonlinear sampling during evolution time for optimal scan time without any compromises in fit accuracy. The relaxation times T1 and T2 and the TQ signals from IRTQTPPI and TQTPPI were compared between 9.4 and 21.1 T. The motional environment of the sodium nuclei was evaluated by calculation of correlation times and nuclear quadrupole interaction strengths. RESULTS Reliable measurements of the T1-TQ signals and T1 bi-exponential relaxation times were demonstrated. The fit parameters for all four phase cycles were in good agreement with one another, with a negligible influence of unwanted signals. The agar samples yielded normalized T1-TQ signals from 3% to 16% relative to single quantum (SQ) signals at magnetic fields of both 9.4 and 21.1 T. In comparison, the normalized T2-TQ signal was in the range 15%-35%. The TQ/SQ signal ratio was decreased at 21.1 T as compared with 9.4 T for both T1 and T2 relaxation pathways. The bi-exponential T1 relaxation time separation ranged from 15 to 18 ms at 9.4 T and 15 to 21 ms at 21.1 T. The T2 relaxation time separation was larger, ranging from 28 to 35 ms at 9.4 T and 37 to 40 ms at 21.1 T. CONCLUSION The IRTQTPPI sequence, while providing a less intensive TQ signal than TQTPPI, allows a simultaneous and reliable quantification of both the T1-TQ signal and T1 relaxation times. The unique sensitivities of the T1 and T2 relaxation pathways to different types of molecular motion provide a deeper understanding of the sodium MR environment.
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Affiliation(s)
- Simon Reichert
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Cooperative Core Facility Animal Scanner ZI, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Victor Schepkin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA
| | - Dennis Kleimaier
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Frank G Zöllner
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Cooperative Core Facility Animal Scanner ZI, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Lothar R Schad
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Gast LV, Platt T, Nagel AM, Gerhalter T. Recent technical developments and clinical research applications of sodium ( 23Na) MRI. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2023; 138-139:1-51. [PMID: 38065665 DOI: 10.1016/j.pnmrs.2023.04.002] [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: 01/27/2023] [Revised: 04/11/2023] [Accepted: 04/13/2023] [Indexed: 12/18/2023]
Abstract
Sodium is an essential ion that plays a central role in many physiological processes including the transmembrane electrochemical gradient and the maintenance of the body's homeostasis. Due to the crucial role of sodium in the human body, the sodium nucleus is a promising candidate for non-invasively assessing (patho-)physiological changes. Almost 10 years ago, Madelin et al. provided a comprehensive review of methods and applications of sodium (23Na) MRI (Madelin et al., 2014) [1]. More recent review articles have focused mainly on specific applications of 23Na MRI. For example, several articles covered 23Na MRI applications for diseases such as osteoarthritis (Zbyn et al., 2016, Zaric et al., 2020) [2,3], multiple sclerosis (Petracca et al., 2016, Huhn et al., 2019) [4,5] and brain tumors (Schepkin, 2016) [6], or for imaging certain organs such as the kidneys (Zollner et al., 2016) [7], the brain (Shah et al., 2016, Thulborn et al., 2018) [8,9], and the heart (Bottomley, 2016) [10]. Other articles have reviewed technical developments such as radiofrequency (RF) coils for 23Na MRI (Wiggins et al., 2016, Bangerter et al., 2016) [11,12], pulse sequences (Konstandin et al., 2014) [13], image reconstruction methods (Chen et al., 2021) [14], and interleaved/simultaneous imaging techniques (Lopez Kolkovsky et al., 2022) [15]. In addition, 23Na MRI topics have been covered in review articles with broader topics such as multinuclear MRI or ultra-high-field MRI (Niesporek et al., 2019, Hu et al., 2019, Ladd et al., 2018) [16-18]. During the past decade, various research groups have continued working on technical improvements to sodium MRI and have investigated its potential to serve as a diagnostic and prognostic tool. Clinical research applications of 23Na MRI have covered a broad spectrum of diseases, mainly focusing on the brain, cartilage, and skeletal muscle (see Fig. 1). In this article, we aim to provide a comprehensive summary of methodological and hardware developments, as well as a review of various clinical research applications of sodium (23Na) MRI in the last decade (i.e., published from the beginning of 2013 to the end of 2022).
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Affiliation(s)
- Lena V Gast
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Tanja Platt
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
| | - Armin M Nagel
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany; Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
| | - Teresa Gerhalter
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
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Wu C, Blunck Y, Johnston LA. The "Spin-3/2 Bloch Equation": System matrix formalism of excitation, relaxation, and off-resonance effects in biological tissue. Magn Reson Med 2022; 88:1370-1379. [PMID: 35608214 DOI: 10.1002/mrm.29276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 04/03/2022] [Accepted: 04/04/2022] [Indexed: 11/12/2022]
Abstract
PURPOSE This work proposes "Spin-3/2 Bloch Equation" (SBE), a consolidated formalism for spin-3/2 dynamics in biological environments. The formalism encapsulates excitation, relaxation, and off-resonance with accessible matrix representation for a straightforward implementation with high computational efficiency. THEORY The SBE is derived using spherical tensor operators to encapsulate the spin-3/2 dynamics in biological systems in a single system matrix, a formalism akin to the well-known Bloch Equations (BE). METHODS Using the proposed SBE, simulations of three classical 23 Na pulse sequences were performed to demonstrate the versatility and applicability of the model, returning the evolution of the 23 Na spin system during these experiments: soft rectangular and adiabatic inversion recovery (IR) and triple-quantum filtering. IR simulations were compared with two existing spin-3/2 simulators and the adaptive BE as a first-order approximation. RESULTS The proposed SBE is straightforward to implement and facilitates accurate and fast simulations of the underlying higher order coherence in sodium experiments of biological tissues. SBE simulations and comparison spin-3/2 simulators outperform the BE simulations as expected, with the SBE offering superior computational efficiency achieved by the single system matrix formalism. CONCLUSION The proposed SBE enables comprehensive and accurate simulations for spin-3/2 systems in biological tissue. With a one-line call to an ordinary differential equation solver, it offers a computationally efficient and accessible method for use in 23 Na pulse sequence design.
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Affiliation(s)
- Chengchuan Wu
- Melbourne Brain Centre Imaging Unit, The University of Melbourne, Parkville, Victoria, Australia.,Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Yasmin Blunck
- Melbourne Brain Centre Imaging Unit, The University of Melbourne, Parkville, Victoria, Australia.,Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Leigh A Johnston
- Melbourne Brain Centre Imaging Unit, The University of Melbourne, Parkville, Victoria, Australia.,Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
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Water and Ion Dynamics in Confined Media: A Multi-Scale Study of the Clay/Water Interface. COLLOIDS AND INTERFACES 2021. [DOI: 10.3390/colloids5020034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This review details a large panel of experimental studies (Inelastic Neutron Scattering, Quasi-Elastic Neutron Scattering, Nuclear Magnetic Resonance relaxometry, Pulsed-Gradient Spin-Echo attenuation, Nuclear Magnetic Resonance Imaging, macroscopic diffusion experiments) used recently to probe, over a large distribution of characteristic times (from pico-second up to days), the dynamical properties of water molecules and neutralizing cations diffusing within clay/water interfacial media. The purpose of this review is not to describe these various experimental methods in detail but, rather, to investigate the specific dynamical information obtained by each of them concerning these clay/water interfacial media. In addition, this review also illustrates the various numerical methods (quantum Density Functional Theory, classical Molecular Dynamics, Brownian Dynamics, macroscopic differential equations) used to interpret these various experimental data by analyzing the corresponding multi-scale dynamical processes. The purpose of this multi-scale study is to perform a bottom-up analysis of the dynamical properties of confined ions and water molecules, by using complementary experimental and numerical studies covering a broad range of diffusion times (between pico-seconds up to days) and corresponding diffusion lengths (between Angstroms and centimeters). In the context of such a bottom-up approach, the numerical modeling of the dynamical properties of the diffusing probes is based on experimental or numerical investigations performed on a smaller scale, thus avoiding the use of empirical or fitted parameters.
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Hoesl MAU, Schad LR, Rapacchi S. Efficient 23 Na triple-quantum signal imaging on clinical scanners: Cartesian imaging of single and triple-quantum 23 Na (CRISTINA). Magn Reson Med 2020; 84:2412-2428. [PMID: 32463978 PMCID: PMC7402015 DOI: 10.1002/mrm.28284] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 01/15/2023]
Abstract
PURPOSE To capture the multiquantum coherence (MQC) 23 Na signal. Different phase-cycling options and sequences are compared in a unified theoretical layout, and a novel sequence is developed. METHODS An open source simulation overview is provided with graphical explanations to facilitate MQC understanding and access to techniques. Biases such as B0 inhomogeneity and stimulated echo signal were simulated for 4 different phase-cycling options previously described. Considerations for efficiency and accuracy lead to the implementation of a 2D Cartesian single and triple quantum imaging of sodium (CRISTINA) sequence employing two 6-step cycles in combination with a multi-echo readout. CRISTINA was compared to simultaneous single-quantum and triple-quantum-filtered MRI of sodium (SISTINA) under strong static magnetic gradient. CRISTINA capabilities were assessed on 8 × 60 mL, 0% to 5% agarose phantom with 50 to 154 mM 23 Na concentration at 7 T. CRISTINA was demonstrated subsequently in vivo in the brain. RESULTS Simulation of B0 inhomogeneity showed severe signal dropout, which can lead to erroneous MQC measurement. Stimulated echo signal was highest at the time of triple-quantum coherences signal maximum. However, stimulated echo signal is separated by Fourier Transform as an offset and did not interfere with MQC signals. The multi-echo readout enabled capturing both single-quantum coherences and triple-quantum coherences signal evolution at once. Signal combination of 2 phase-cycles with a corresponding B0 map was found to recover the signal optimally. Experimental results confirm and complement the simulations. CONCLUSION Considerations for efficient MQC measurements, most importantly avoiding B0 signal loss, led to the design of CRISTINA. CRISTINA captures triple-quantum coherences and single-quantum coherences signal evolution to provide complete sodium signal characterization including T 2 ∗ fast, T 2 ∗ slow, MQC amplitudes, and sodium concentration.
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Affiliation(s)
| | - Lothar R. Schad
- Computer Assisted Clinical MedicineHeidelberg UniversityMannheimGermany
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Kleimaier D, Schepkin V, Hu R, Schad LR. Protein conformational changes affect the sodium triple-quantum MR signal. NMR IN BIOMEDICINE 2020; 33:e4367. [PMID: 32656956 DOI: 10.1002/nbm.4367] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 06/10/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
The aim of this study was to investigate possible sodium triple-quantum (TQ) signal dependence on pH variation and protein unfolding which may happen in vivo. The model system, composed of bovine serum albumin (BSA), was investigated over a wide pH range of 0.70 to 13.05 and during urea-induced unfolding. In both experimental series, the sodium and BSA concentration were kept constant so that TQ signal changes solely arose from an environmental change. The experiments were performed using unique potential to detect weak TQ signals by implementing a TQ time proportional phase increment pulse sequence. At a pH of 0.70, in which case the effect of the negatively charged groups was minimized, the minimum TQ percentage relative to single-quantum of 1.34% ± 0.05% was found. An increase of the pH up to 13.05 resulted in an increase of the sodium TQ signal by 225%. Urea-induced unfolding of BSA, without changes in pH, led to a smaller increase in the sodium TQ signal of up to 40%. The state of BSA unfolding was verified by fluorescence microscopy. Results of both experiments were well fitted by sigmoid functions. Both TQ signal increases were in agreement with an increase of the availability of negatively charged groups. The results point to vital contributions of the biochemical environment to the TQ MR signals. The sodium TQ signal in vivo could be a valuable biomarker of cell viability, and therefore possible effects of pH and protein unfolding need to be considered for a proper interpretation of changes in sodium TQ signals.
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Affiliation(s)
- Dennis Kleimaier
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| | - Victor Schepkin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, USA
| | - Ruomin Hu
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| | - Lothar R Schad
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
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Porion P, Delville A. A Multi-Scale Study of Water Dynamics under Confinement, Exploiting Numerical Simulations in Relation to NMR Relaxometry, PGSE and NMR Micro-Imaging Experiments: An Application to the Clay/Water Interface. Int J Mol Sci 2020; 21:E4697. [PMID: 32630160 PMCID: PMC7369841 DOI: 10.3390/ijms21134697] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/19/2020] [Accepted: 06/22/2020] [Indexed: 11/17/2022] Open
Abstract
Water mobility within the porous network of dense clay sediments was investigated over a broad dynamical range by using 2H nuclear magnetic resonance spectroscopy. Multi-quanta 2H NMR spectroscopy and relaxation measurements were first performed to identify the contributions of the various relaxation mechanisms monitoring the time evolution of the nuclear magnetisation of the confined heavy water. Secondly, multi-quanta spin-locking NMR relaxation measurements were then performed over a broad frequency domain, probing the mobility of the confined water molecules on a time-scale varying between microseconds and milliseconds. Thirdly, 1H NMR pulsed-gradient spin-echo attenuation experiments were performed to quantify water mobility on a time-scale limited by the NMR transverse relaxation time of the confined NMR probe, typically a few milliseconds. Fourthly, the long living quantum state of the magnetisation of quadrupolar nuclei was exploited to probe a two-time correlation function at a time-scale reaching one second. Finally, magnetic resonance imaging measurements allow probing the same dynamical process on time-scales varying between seconds and several hours. In that context, multi-scale modelling is required to interpret these NMR measurements and extract information on the influences of the structural properties of the porous network on the apparent mobility of the diffusing water molecules. That dual experimental and numerical approach appears generalizable to a large variety of porous networks, including zeolites, micelles and synthetic or biological membranes.
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Affiliation(s)
- Patrice Porion
- Interfaces, Confinement, Matériaux et Nanostructures (ICMN), UMR 7374, CNRS and Université d’Orléans, 1b rue de la Férollerie, CS 40059, CEDEX 2, F-45071 Orléans, France
| | - Alfred Delville
- Interfaces, Confinement, Matériaux et Nanostructures (ICMN), UMR 7374, CNRS and Université d’Orléans, 1b rue de la Férollerie, CS 40059, CEDEX 2, F-45071 Orléans, France
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Wilferth T, Gast LV, Stobbe RW, Beaulieu C, Hensel B, Uder M, Nagel AM. 23Na MRI of human skeletal muscle using long inversion recovery pulses. Magn Reson Imaging 2019; 63:280-290. [PMID: 31425815 DOI: 10.1016/j.mri.2019.08.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/05/2019] [Accepted: 08/15/2019] [Indexed: 12/20/2022]
Abstract
23Na inversion recovery (IR) imaging allows for a weighting toward intracellular sodium in the human calf muscle and thus enables an improved analysis of pathophysiological changes of the muscular ion homeostasis. However, sodium signal-to-noise ratio (SNR) is low, especially when using IR sequences. 23Na has a nuclear spin of 3/2 and therefore experiences a strong electrical quadrupolar interaction. This results in very short relaxation times as well as in possible residual quadrupolar splitting. Consequently, relaxation effects during a radiofrequency pulse can no longer be neglected and even allow for increasing SNR as has previously been shown for human brain and knee. The aim of this work was to increase the SNR in 23Na IR imaging of the human calf muscle by using long inversion pulses instead of the usually applied short pulses. First, the influence of the inversion pulse length (1 to 20 ms) on the SNR as well as on image contrast was simulated for different model environments and verified by phantom measurements. Depending on the model environment (agarose 4% and 8%, xanthan 2% and 3%), SNR values increased by a factor of 1.15 up to 1.35, while NaCl solution was successfully suppressed. Thus, image contrast between the non-suppressed model compartments changes with IR pulse length. Finally, in vivo measurements of the human calf muscle of ten healthy volunteers were conducted at 3 Tesla. On average, a 1.4-fold increase in SNR could be achieved by increasing the inversion pulse length from 1 ms to 20 ms, leaving all other parameters - including the scan time - constant. This enables 23Na IR MRI with improved spatial resolution or reduced acquisition time.
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Affiliation(s)
- Tobias Wilferth
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Lena V Gast
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Robert W Stobbe
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Christian Beaulieu
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Bernhard Hensel
- Center for Medical Physics and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Michael Uder
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Armin M Nagel
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany; Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Medical Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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Schepkin VD. Statistical tensor analysis of the MQ MR signals generated by weak quadrupole interactions. Z Med Phys 2019; 29:326-336. [PMID: 31160139 DOI: 10.1016/j.zemedi.2019.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/02/2019] [Accepted: 03/27/2019] [Indexed: 11/16/2022]
Abstract
Multiple quantum NMR signals that appear in the presence of weak quadrupole interactions were formulated using statistical tensors (Fano, 1957). The approach aimed to present a concise and a computer-based tool for a detailed analysis and modification of the MQ pulse sequences. The calculation avoids a lengthy procedure of utilizing exponential operators and, moreover, the same formulae are applicable for any interval in the TQ pulse sequence, as well as any spin value. The quantum operator algebra was implemented using "Mathematica" software (Wolfram Inc.). The results of tensor's evolutions in the TQ pulse sequence were graphically illustrated using corresponding spherical harmonics. The visualization takes into consideration the parity properties of irreducible tensors and the corresponding spherical harmonics.
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Affiliation(s)
- Victor D Schepkin
- CIMAR, National High Magnetic Field Laboratory/FSU, Tallahassee, FL, USA.
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Hoesl MAU, Kleimaier D, Hu R, Malzacher M, Nies C, Gottwald E, Schad LR. 23 Na Triple-quantum signal of in vitro human liver cells, liposomes, and nanoparticles: Cell viability assessment vs. separation of intra- and extracellular signal. J Magn Reson Imaging 2019; 50:435-444. [PMID: 30681221 DOI: 10.1002/jmri.26666] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/10/2019] [Accepted: 01/10/2019] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Triple-quantum (TQ) filtered sequences have become more popular in sodium MR due to the increased usage of scanners with field strengths exceeding 3T. Disagreement as to whether TQ signal can provide separation of intra- and extracellular compartments persists. PURPOSE To provide insight into TQ signal behavior on a cellular level. STUDY TYPE Prospective. PHANTOM/SPECIMEN Cell-phantoms in the form of liposomes, encapsulated 0 mM, 145 mM, 154 mM Na+ in a double-lipid membrane similar to cells. Poly(lactic-co-glycolic acid) nanoparticles encapsulated 154 mM Na+ within a single-layer membrane structure. Two microcavity chips with each 6 × 106 human HEP G2 liver cells were measured in an MR-compatible bioreactor. FIELD STRENGTH/SEQUENCE Spectroscopic TQ sequence with time proportional phase-increments at 9.4T. ASSESSMENT The TQ signal of viable, dead cells, and cell-phantoms was assessed by a fit in the time domain and by the amplitude in the frequency domain. STATISTICAL TESTS The noise variance (σ) was evaluated to express the deviation of the measured TQ signal amplitude from noise. RESULTS TQ signal >20σ was found for liposomes encapsulating sodium ions. Liposomal encapsulation of 0 mM Na+ and 154 mM Na+ encapsulation in the nanoparticles resulted in <2σ TQ signal. Cells under normal perfusion resulted in >9σ TQ signal. Compared with TQ signal under normal perfusion, a 56% lower TQ signal of was observed (25σ) during perfusion stop. TQ signal returned to 92% of the initial signal after reperfusion. DATA CONCLUSION Our measurements indicate that TQ signal in liposomes was observed due to the trapping of ions within the double-lipid membrane rather than from the intraliposomal space. Transfer to the cell results suggests that TQ signal was observed from motion restriction equivalent to trapping. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:435-444.
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Affiliation(s)
- Michaela A U Hoesl
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| | - Dennis Kleimaier
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| | - Ruomin Hu
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| | - Matthias Malzacher
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| | - Cordula Nies
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Eric Gottwald
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Lothar R Schad
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
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Multi-Quanta Spin-Locking Nuclear Magnetic Resonance Relaxation Measurements: An Analysis of the Long-Time Dynamical Properties of Ions and Water Molecules Confined within Dense Clay Sediments. MAGNETOCHEMISTRY 2017. [DOI: 10.3390/magnetochemistry3040035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Storek M, Adjei-Acheamfour M, Christensen R, Martin SW, Böhmer R. Positive and Negative Mixed Glass Former Effects in Sodium Borosilicate and Borophosphate Glasses Studied by 23Na NMR. J Phys Chem B 2016; 120:4482-95. [DOI: 10.1021/acs.jpcb.6b00482] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael Storek
- Fakultät
Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | | | - Randilynn Christensen
- Department
of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, United States
| | - Steve W. Martin
- Department
of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, United States
| | - Roland Böhmer
- Fakultät
Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
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14
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Rösler MB, Nagel AM, Umathum R, Bachert P, Benkhedah N. In vivo observation of quadrupolar splitting in (39)K magnetic resonance spectroscopy of human muscle tissue. NMR IN BIOMEDICINE 2016; 29:451-457. [PMID: 26837061 DOI: 10.1002/nbm.3476] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 11/02/2015] [Accepted: 11/28/2015] [Indexed: 06/05/2023]
Abstract
The purpose of this work was to explore the origin of oscillations of the T(*)2 decay curve of (39)K observed in studies of (39)K magnetic resonance imaging of the human thigh. In addition to their magnetic dipole moment, spin-3/2 nuclei possess an electric quadrupole moment. Its interaction with non-vanishing electrical field gradients leads to oscillations in the free induction decay and to splitting of the resonance. All measurements were performed on a 7T whole-body MRI scanner (MAGNETOM 7T, Siemens AG, Erlangen, Germany) with customer-built coils. According to the theory of quadrupolar splitting, a model with three Lorentzian-shaped peaks is appropriate for (39)K NMR spectra of the thigh and calf. The frequency shifts of the satellites depend on the angle between the calf and the static magnetic field. When the leg is oriented parallel to the static magnetic field, the satellites are shifted by about 200 Hz. In the thigh, rank-2 double quantum coherences arising from anisotropic quadrupolar interaction are observed by double-quantum filtration with magic-angle excitation. In addition to the spectra, an image of the thigh with a nominal resolution of (16 × 16 × 32) mm(3) was acquired with this filtering technique in 1:17 h. From the line width of the resonances, (39)K transverse relaxation time constants T(*)2, fast = (0.51 ± 0.01) ms and T(*)2, slow = (6.21 ± 0.05) ms for the head were determined. In the thigh, the left and right satellite, both corresponding to the short component of the transverse relaxation time constant, take the following values: T(*)2, fast = (1.56 ± 0.03) ms and T(*)2, fast = (1.42 ± 0.03) ms. The centre line, which corresponds to the slow component, is T(*)2, slow = (9.67 ± 0.04) ms. The acquisition time of the spectra was approximately 10 min. Our results agree well with a non-vanishing electrical field gradient interacting with (39)K nuclei in the intracellular space of muscle tissue.
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Affiliation(s)
- M B Rösler
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - A M Nagel
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - R Umathum
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - P Bachert
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - N Benkhedah
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
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15
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Feldman RE, Stobbe R, Watts A, Beaulieu C. Sodium imaging of the human knee using soft inversion recovery fluid attenuation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 234:197-206. [PMID: 23896067 DOI: 10.1016/j.jmr.2013.06.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 06/27/2013] [Accepted: 06/30/2013] [Indexed: 06/02/2023]
Abstract
Sodium signal strength in MRI is low when compared with (1)H. Thus, image voxel volumes must be relatively large in order to produce a sufficient signal-to-noise ratio (SNR). The measurement of sodium in cartilage is hindered by conflation with signal from the adjacent fluid spaces. Inversion recovery can be used to null signal from fluid, but reduces SNR. The purpose of this work was to optimize inversion recovery sodium MRI to enhance cartilage SNR while nulling fluid. Sodium relaxation was first measured for knee cartilage (T1=21±1 ms, T(2 fast)(∗)=0.8±0.2 ms, T(2 slow)(∗)=19.7±0.5 ms) and fluid (T1=48±3 ms, T2(∗)=47±4 ms) in nine healthy subjects at 4.7 T. The rapid relaxation of cartilage in relation to fluid permits the use of a lengthened inversion pulse to preferentially invert the fluid components. Simulations of inversion pulse length were performed to yield a cartilage SNR enhancing combination of parameters that nulled fluid. The simulations were validated in a phantom and then in vivo. B0 inhomogeneity was measured and the effect of off-resonance during the soft inversion pulse was assessed with simulation. Soft inversion recovery yielded twice the SNR and much improved sodium images of cartilage in human knee with little confounding signal from fluid.
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16
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Kotecha M, Ravindran S, Schmid TM, Vaidyanathan A, George A, Magin RL. Application of sodium triple-quantum coherence NMR spectroscopy for the study of growth dynamics in cartilage tissue engineering. NMR IN BIOMEDICINE 2013; 26:709-17. [PMID: 23378198 PMCID: PMC3634872 DOI: 10.1002/nbm.2916] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 10/23/2012] [Accepted: 12/09/2012] [Indexed: 06/01/2023]
Abstract
We studied the tissue growth dynamics of tissue-engineered cartilage at an early growth stage after cell seeding for four weeks using sodium triple-quantum coherence NMR spectroscopy. The following tissue-engineering constructs were studied: 1) bovine chondrocytes cultured in alginate beads; 2) bovine chondrocytes cultured as pellets (scaffold-free chondrocyte pellets); and 3) human marrow stromal cells (HMSCs) seeded in collagen/chitosan based biomimetic scaffolds. We found that the sodium triple-quantum coherence spectroscopy could differentiate between different tissue-engineered constructs and native tissues based on the fast and slow components of relaxation rate as well as on the average quadrupolar coupling. Both fast (Tf ) and slow (Ts ) relaxation times were found to be longer in chondrocyte pellets and biomimetic scaffolds compared to chondrocytes suspended in alginate beads and human articular cartilage tissues. In all cases, it was found that relaxation rates and motion of sodium ions measured from correlation times were dependent on the amount of macromolecules, high cell density and anisotropy of the cartilage tissue-engineered constructs. Average quadrupolar couplings were found to be lower in the engineered tissue compared to native tissue, presumably due to the lack of order in collagen accumulated in the engineered tissue. These results support the use of sodium triple-quantum coherence spectroscopy as a tool to investigate anisotropy and growth dynamics of cartilage tissue-engineered constructs in a simple and reliable way.
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Affiliation(s)
- Mrignayani Kotecha
- Department of Bioengineering, University of Illinois at Chicago, IL 60607, USA.
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17
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Bain AD, Berno B. Liouvillians in NMR: the direct method revisited. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2011; 59:223-244. [PMID: 21920219 DOI: 10.1016/j.pnmrs.2010.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2010] [Accepted: 12/16/2010] [Indexed: 05/31/2023]
Affiliation(s)
- Alex D Bain
- Department of Chemistry and Chemical Biology, McMaster University 1280 Main St., West Hamilton, Ontario, Canada L8S 4M1.
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18
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Watts A, Stobbe RW, Beaulieu C. Signal-to-noise optimization for sodium MRI of the human knee at 4.7 Tesla using steady state. Magn Reson Med 2011; 66:697-705. [PMID: 21437972 DOI: 10.1002/mrm.22838] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 12/17/2010] [Accepted: 12/27/2010] [Indexed: 11/07/2022]
Abstract
Sodium magnetic resonance imaging of knee cartilage is a possible diagnostic method for osteoarthritis, but low signal-to-noise ratio yields low spatial resolution images and long scan times. For a given scan time, a steady-state approach with reduced repetition time and increased averaging may improve signal-to-noise ratio and hence attainable resolution. However, repetition time reduction results in increased power deposition, which must be offset with increased radiofrequency pulse length and/or reduced flip angle to maintain an acceptable specific absorption rate. Simulations varying flip angle, repetition time, and radiofrequency pulse length were performed for constant power deposition corresponding to ∼6 W/kg over the human knee at 4.7 T. For 10% agar, simulation closely matched experiment. For healthy human knee cartilage, a 37% increase in signal-to-noise ratio was predicted for steady-state over "fully relaxed" parameters while a 29% ± 4% increase was determined experimentally (n=10). Partial volume of cartilage with synovial fluid, inaccurate relaxation parameters used in simulation, and/or quadrupolar splitting may be responsible for this disagreement. Excellent quality sodium images of the human knee were produced in 9 mins at 4.7 T using the signal-to-noise ratio enhancing steady-state technique.
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Affiliation(s)
- Alexander Watts
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
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19
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Cleveland ZI, Pavlovskaya GE, Elkins ND, Stupic KF, Repine JE, Meersmann T. Hyperpolarized 83Kr MRI of lungs. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 195:232-7. [PMID: 18948043 DOI: 10.1016/j.jmr.2008.09.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 09/05/2008] [Accepted: 09/10/2008] [Indexed: 05/22/2023]
Abstract
Hyperpolarized (hp) (83)Kr (spin I=9/2) is a promising gas-phase contrast agent that displays sensitivity to the surface chemistry, surface-to-volume ratio, and surface temperature of the surrounding environment. This proof-of-principle study demonstrates the feasibility of ex vivo hp (83)Kr magnetic resonance imaging (MRI) of lungs using natural abundance krypton gas (11.5% (83)Kr) and excised, but otherwise intact, rat lungs located within a custom designed ventilation chamber. Experiments comparing the (83)Kr MR signal intensity from lungs to that arising from a balloon with no internal structure inflated to the same volume with krypton gas mixture suggest that most of the observed signal originated from the alveoli and not merely the conducting airways. The (83)Kr longitudinal relaxation times in the rat lungs ranged from 0.7 to 3.7s but were reproducible for a given lung. Although the source of these variations was not explored in this work, hp (83)Kr T(1) differences may ultimately lead to a novel form of MRI contrast in lungs. The currently obtained 1200-fold signal enhancement for hp (83)Kr at 9.4T field strength is found to be 180 times below the theoretical upper limit.
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Affiliation(s)
- Zackary I Cleveland
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
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20
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Stobbe R, Beaulieu C. Sodium imaging optimization under specific absorption rate constraint. Magn Reson Med 2008; 59:345-55. [DOI: 10.1002/mrm.21468] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Borthakur A, Mellon E, Niyogi S, Witschey W, Kneeland JB, Reddy R. Sodium and T1rho MRI for molecular and diagnostic imaging of articular cartilage. NMR IN BIOMEDICINE 2006; 19:781-821. [PMID: 17075961 PMCID: PMC2896046 DOI: 10.1002/nbm.1102] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In this article, both sodium magnetic resonance (MR) and T1rho relaxation mapping aimed at measuring molecular changes in cartilage for the diagnostic imaging of osteoarthritis are reviewed. First, an introduction to structure of cartilage, its degeneration in osteoarthritis (OA) and an outline of diagnostic imaging methods in quantifying molecular changes and early diagnostic aspects of cartilage degeneration are described. The sodium MRI section begins with a brief overview of the theory of sodium NMR of biological tissues and is followed by a section on multiple quantum filters that can be used to quantify both bi-exponential relaxation and residual quadrupolar interaction. Specifically, (i) the rationale behind the use of sodium MRI in quantifying proteoglycan (PG) changes, (ii) validation studies using biochemical assays, (iii) studies on human OA specimens, (iv) results on animal models and (v) clinical imaging protocols are reviewed. Results demonstrating the feasibility of quantifying PG in OA patients and comparison with that in healthy subjects are also presented. The section concludes with the discussion of advantages and potential issues with sodium MRI and the impact of new technological advancements (e.g. ultra-high field scanners and parallel imaging methods). In the theory section on T1rho, a brief description of (i) principles of measuring T1rho relaxation, (ii) pulse sequences for computing T1rho relaxation maps, (iii) issues regarding radio frequency power deposition, (iv) mechanisms that contribute to T1rho in biological tissues and (v) effects of exchange and dipolar interaction on T1rho dispersion are discussed. Correlation of T1rho relaxation rate with macromolecular content and biomechanical properties in cartilage specimens subjected to trypsin and cytokine-induced glycosaminoglycan depletion and validation against biochemical assay and histopathology are presented. Experimental T1rho data from osteoarthritic specimens, animal models, healthy human subjects and as well from osteoarthritic patients are provided. The current status of T1rho relaxation mapping of cartilage and future directions is also discussed.
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Affiliation(s)
- Arijitt Borthakur
- MMRRCC, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104-6100, USA
| | - Eric Mellon
- MMRRCC, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104-6100, USA
| | - Sampreet Niyogi
- MMRRCC, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104-6100, USA
| | - Walter Witschey
- MMRRCC, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104-6100, USA
| | - J. Bruce Kneeland
- MMRRCC, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104-6100, USA
| | - Ravinder Reddy
- MMRRCC, Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104-6100, USA
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22
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Stobbe R, Beaulieu C. In vivo sodium magnetic resonance imaging of the human brain using soft inversion recovery fluid attenuation. Magn Reson Med 2006; 54:1305-10. [PMID: 16217782 DOI: 10.1002/mrm.20696] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sodium imaging with soft inversion recovery fluid attenuation, which may be advantageous for intracellular weighting, was demonstrated with cerebrospinal fluid (CSF) suppression in five healthy volunteers at 4.7 T. Long rectangular inversion pulses reduce the average power deposition in an inversion recovery sequence, allowing repetition time to be shortened and more averages acquired for a given scan length. Longer pulses also significantly reduce the "depth" of Mz inversion in environments with rapid T1 and T2 relaxation (i.e., brain relative to CSF). Phantom experiments and simulation show a marked SNR increase when using a 10-ms, rather than a 1-ms, rectangular inversion pulse. Images were acquired in 11.1 min with a voxel size of 0.25 cm3 and the SNR in CSF, which is typically approximately 3 times larger than in brain, was reduced to 23% of that in the brain tissue, which had an average SNR of 17.
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Affiliation(s)
- Robert Stobbe
- Department of Biomedical Engineering, University of Alberta, Alberta, Canada
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23
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Porion P, Faugère AM, Delville A. Analysis of the Degree of Nematic Ordering within Dense Aqueous Dispersions of Charged Anisotropic Colloids by 23Na NMR Spectroscopy. J Phys Chem B 2005; 109:20145-54. [PMID: 16853604 DOI: 10.1021/jp053224i] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Aqueous dispersions of Laponite, a synthetic clay neutralized by sodium counterions, are used as a model of charged anisotropic colloids to probe the influence of the shape of the particle on their organization within a macroscopic nematic phase. Because of the large fraction of condensed sodium counterions in the vicinity of the clay particle, (23)Na NMR is a sensitive probe of the nematic ordering of the clay dispersions. We used line shape analysis of the (23)Na NMR spectra and measurements of the Hahn echo attenuation to quantify the degree of alignment of the individual clay particles along a single nematic director. As justified by simple dynamical simulations of the interplay between the sodium quadrupolar relaxation and its diffusion through the porous network limited by the surface of the clay particles, we probe the degree of ordering within these clay nematic dispersions by measuring the variation of the apparent (23)Na NMR relaxation rates as a function of the macroscopic orientation of the clay dispersion within the magnetic field.
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Affiliation(s)
- Patrice Porion
- Centre de Recherche sur la Matière Divisée CNRS, 1b rue de la Férollerie, 45071 Orléans Cedex 02, France.
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24
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Bain AD, Khasawneh M. From NQR to NMR: The complete range of quadrupole interactions. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/cmr.a.20013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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