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Yan Z, Zhang R. Measurement of spin-lattice relaxation times in multiphase polymer systems. J Magn Reson 2023; 357:107597. [PMID: 37984029 DOI: 10.1016/j.jmr.2023.107597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/25/2023] [Accepted: 11/13/2023] [Indexed: 11/22/2023]
Abstract
Solid-state Nuclear Magnetic Resonance (NMR) has emerged as a pivotal technique for unraveling the microstructure and dynamics of intricate polymer and biological materials. Within this context, site-specific proton spin-lattice relaxation times in the laboratory frame (T1) and rotating frame (T1ρ) have become indispensable tools for investigating phase separation structures and molecular dynamics in multiphase polymer systems. Notably, the site-specific measurement of proton T1 and T1ρ is usually achieved via 13C detection in polymers, where 1H polarization is typically transferred to 13C via cross polarization (CP). Nevertheless, CP relies on the 1H-13C heteronuclear dipolar couplings, and thus it does not work well for the mobile components. In this study, via the integration of CP and RINEPT (refocused insensitive nuclei enhanced by polarization transfer), we propose a robust approach for the measurement of site-specific proton T1 and T1ρ in multiphase polymers. It overcomes the limitation of CP on transferring 1H polarization to 13C in mobile components, and thus enables simultaneous determination of site-specific proton T1 and T1ρ in rigid and mobile components in multiphase polymers in a single experiment. Such experiment can also be used for dynamics-based spectral editing due to the dynamic selectivity of CP- and RINEPT-based polarization transfer process. The proposed experiments are well demonstrated on three typical multiphase polymer systems, poly(methyl methacrylate)/polybutadiene (PMMA/PB) polymer blend, polyurethane (PU) and polystyrene-polybutadiene-polystyrene (SBS) elastomers. We envisage the proposed experiments can be a universal avenue for structural and dynamic elucidation of multiphase polymers containing both rigid and mobile components.
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Affiliation(s)
- Zhiwei Yan
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter (SESM), South China University of Technology, Guangzhou, 510640, PR China
| | - Rongchun Zhang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter (SESM), South China University of Technology, Guangzhou, 510640, PR China; Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou, 510640, PR China.
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2
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Stout JN, Liao C, Gagoski B, Turk EA, Feldman HA, Bibbo C, Barth WH, Shainker SA, Wald LL, Grant PE, Adalsteinsson E. Quantitative T 1 and T 2 mapping by magnetic resonance fingerprinting (MRF) of the placenta before and after maternal hyperoxia. Placenta 2021; 114:124-132. [PMID: 34537569 DOI: 10.1016/j.placenta.2021.08.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 06/16/2021] [Accepted: 08/05/2021] [Indexed: 11/13/2022]
Abstract
INTRODUCTION MR relaxometry has been used to assess placental exchange function, but methods to date are not sufficiently fast to be robust to placental motion. Magnetic resonance fingerprinting (MRF) permits rapid, voxel-wise, intrinsically co-registered T1 and T2 mapping. After characterizing measurement error, we scanned pregnant women during air and oxygen breathing to demonstrate MRF's ability to detect placental oxygenation changes. METHODS The accuracy of FISP-based, sliding-window reconstructed MRF was tested on phantoms. MRF scans in 9-s breath holds were acquired at 3T in 31 pregnant women during air and oxygen breathing. A mixed effects model was used to test for changes in placenta relaxation times between physiological states, to assess the dependency on gestational age (GA), and the impact of placental motion. RESULTS MRF estimates of known phantom relaxation times resulted in mean absolute errors for T1 of 92 ms (4.8%), but T2 was less accurate at 16 ms (13.6%). During normoxia, placental T1 = 1825 ± 141 ms (avg ± standard deviation) and T2 = 60 ± 16 ms (gestational age range 24.3-36.7, median 32.6 weeks). In the statistical model, placental T2 rose and T1 remained contant after hyperoxia, and no GA dependency was observed for T1 or T2. DISCUSSION Well-characterized, motion-robust MRF was used to acquire T1 and T2 maps of the placenta. Changes with hyperoxia are consistent with a net increase in oxygen saturation. Toward the goal of whole-placenta quantitative oxygenation imaging over time, we aim to implement 3D MRF with integrated motion correction to improve T2 accuracy.
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Affiliation(s)
- Jeffrey N Stout
- Fetal and Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Boston, MA, 02115, USA.
| | - Congyu Liao
- Department of Radiology, Stanford University, Stanford, CA, 94305, USA
| | - Borjan Gagoski
- Fetal and Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Esra Abaci Turk
- Fetal and Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Henry A Feldman
- Centers for Clinical and Translational Research, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Carolina Bibbo
- Brigham and Women's Hospital, Division of Maternal-Fetal Medicine, Boston, MA, 02115, USA
| | - William H Barth
- Maternal-Fetal Medicine, Obstetrics and Gynecology, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Scott A Shainker
- Maternal-Fetal Medicine, Obstetrics and Gynecology, Beth Israel Deaconess Medical Center, Boston, MA, 02115, USA
| | - Lawrence L Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, 02129, USA
| | - P Ellen Grant
- Fetal and Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Elfar Adalsteinsson
- Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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Li Z, Fu Z, Keerthivasan M, Bilgin A, Johnson K, Galons JP, Vedantham S, Martin DR, Altbach MI. Rapid high-resolution volumetric T 1 mapping using a highly accelerated stack-of-stars Look Locker technique. Magn Reson Imaging 2021; 79:28-37. [PMID: 33722634 DOI: 10.1016/j.mri.2021.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/03/2021] [Accepted: 03/03/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE To develop a fast volumetric T1 mapping technique. MATERIALS AND METHODS A stack-of-stars (SOS) Look Locker technique based on the acquisition of undersampled radial data (>30× relative to Nyquist) and an efficient multi-slab excitation scheme is presented. A principal-component based reconstruction is used to reconstruct T1 maps. Computer simulations were performed to determine the best choice of partitions per slab and degree of undersampling. The technique was validated in phantoms against reference T1 values measured with a 2D Cartesian inversion-recovery spin-echo technique. The SOS Look Locker technique was tested in brain (n = 4) and prostate (n = 5). Brain T1 mapping was carried out with and without kz acceleration and results between the two approaches were compared. Prostate T1 mapping was compared to standard techniques. A reproducibility study was conducted in brain and prostate. Statistical analyses were performed using linear regression and Bland Altman analysis. RESULTS Phantom T1 values showed excellent correlations between SOS Look Locker and the inversion-recovery spin-echo reference (r2 = 0.9965; p < 0.0001) and between SOS Look Locker with slab-selective and non-slab selective inversion pulses (r2 = 0.9999; p < 0.0001). In vivo results showed that full brain T1 mapping (1 mm3) with kz acceleration is achieved in 4 min 21 s. Full prostate T1 mapping (0.9 × 0.9 × 4 mm3) is achieved in 2 min 43 s. T1 values for brain and prostate were in agreement with literature values. A reproducibility study showed coefficients of variation in the range of 0.18-0.2% (brain) and 0.15-0.18% (prostate). CONCLUSION A rapid volumetric T1 mapping technique was developed. The technique enables high-resolution T1 mapping with adequate anatomical coverage in a clinically acceptable time.
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Affiliation(s)
- Zhitao Li
- Department of Electrical and Computer Engineering, the University of Arizona, Tucson, AZ 85721, USA; Department of Medical Imaging, the University of Arizona, Tucson, AZ 85724, USA
| | - Zhiyang Fu
- Department of Electrical and Computer Engineering, the University of Arizona, Tucson, AZ 85721, USA; Department of Medical Imaging, the University of Arizona, Tucson, AZ 85724, USA
| | - Mahesh Keerthivasan
- Department of Medical Imaging, the University of Arizona, Tucson, AZ 85724, USA; Siemens Healthcare USA, Tucson, AZ 85724, USA
| | - Ali Bilgin
- Department of Electrical and Computer Engineering, the University of Arizona, Tucson, AZ 85721, USA; Department of Medical Imaging, the University of Arizona, Tucson, AZ 85724, USA; Department of Biomedical Engineering, the University of Arizona, Tucson, AZ 85721, USA
| | - Kevin Johnson
- Department of Medical Imaging, the University of Arizona, Tucson, AZ 85724, USA
| | | | | | - Diego R Martin
- Department of Medical Imaging, the University of Arizona, Tucson, AZ 85724, USA
| | - Maria I Altbach
- Department of Medical Imaging, the University of Arizona, Tucson, AZ 85724, USA; Department of Biomedical Engineering, the University of Arizona, Tucson, AZ 85721, USA.
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Milshteyn E, Reed GD, Gordon JW, von Morze C, Cao P, Tang S, Leynes AP, Larson PEZ, Vigneron DB. Simultaneous T 1 and T 2 mapping of hyperpolarized 13C compounds using the bSSFP sequence. J Magn Reson 2020; 312:106691. [PMID: 32058912 PMCID: PMC7227792 DOI: 10.1016/j.jmr.2020.106691] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/29/2020] [Accepted: 01/30/2020] [Indexed: 06/10/2023]
Abstract
As in conventional 1H MRI, T1 and T2 relaxation times of hyperpolarized (HP) 13C nuclei can provide important biomedical information. Two new approaches were developed for simultaneous T1 and T2 mapping of HP 13C probes based on balanced steady state free precession (bSSFP) acquisitions: a method based on sequential T1 and T2 mapping modules, and a model-based joint T1/T2 approach analogous to MR fingerprinting. These new methods were tested in simulations, HP 13C phantoms, and in vivo in normal Sprague-Dawley rats. Non-localized T1 values, low flip angle EPI T1 maps, bSSFP T2 maps, and Bloch-Siegert B1 maps were also acquired for comparison. T1 and T2 maps acquired using both approaches were in good agreement with both literature values and data from comparative acquisitions. Multiple HP 13C compounds were successfully mapped, with their relaxation time parameters measured within heart, liver, kidneys, and vasculature in one acquisition for the first time.
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Affiliation(s)
- Eugene Milshteyn
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA.
| | | | - Jeremy W Gordon
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Cornelius von Morze
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Peng Cao
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Shuyu Tang
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Andrew P Leynes
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Daniel B Vigneron
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
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Sucre O, Rondeau-Mouro C. Sequence for simultaneous measurement of long-limit diffusion and longitudinal relaxation in unilateral NMR. J Magn Reson 2019; 309:106619. [PMID: 31706194 DOI: 10.1016/j.jmr.2019.106619] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
When unilateral NMR is employed with large gradients (20 T/m), measurements of T1 using standard sequences become affected by Brownian motion of spins, particularly in samples with long spin-lattice relaxation times T1 (>2000 ms) and a large diffusion coefficient D (2*10-6 mm2/ms). In light of this, a modified saturation sequence which we have called GAUSS-SR is proposed that allows direct measurement of both D and T1 to be carried out subject to certain constraints. The evolution of Mz magnetization is the main phenomenon to be modeled. The sequence is composed of three main parts: (i) a saturation train designed to render the Mz profile in Gaussian form, (ii) a main delay where by the simultaneous effects of T1 and D on this profile has been solved analytically and (iii) a detection train to ensure a good signal-to-noise ratio. An NMR-MOUSE was used to acquire the desired measurement through this sequence. By relying on the coherence of the longitudinal rather than the transverse magnetization component, the sequence successfully provides the long-limit value of the diffusion coefficient.
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Affiliation(s)
- Oscar Sucre
- Irstea, UR OPAALE, 17 avenue de Cucillé, CS 64427, F-35044 Rennes, France; Université Bretagne Loire, France.
| | - Corinne Rondeau-Mouro
- Irstea, UR OPAALE, 17 avenue de Cucillé, CS 64427, F-35044 Rennes, France; Université Bretagne Loire, France
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Bane O, Hectors SJ, Gordic S, Kennedy P, Wagner M, Weiss A, Khaim R, Yi Z, Zhang W, Delaney V, Salem F, He C, Menon MC, Lewis S, Taouli B. Multiparametric magnetic resonance imaging shows promising results to assess renal transplant dysfunction with fibrosis. Kidney Int 2019; 97:414-420. [PMID: 31874802 DOI: 10.1016/j.kint.2019.09.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/31/2019] [Accepted: 09/26/2019] [Indexed: 12/28/2022]
Abstract
Here we assessed the diagnostic value of a quantitative multiparametric magnetic resonance imaging (mpMRI) protocol for evaluation of renal allograft dysfunction with fibrosis. Twenty-seven renal transplant patients, including 15 with stable functional allografts (eGFR mean 71.5 ml/min/1.73m2), and 12 with chronic dysfunction/established fibrosis (eGFR mean 30.1 ml/min/1.73m2), were enrolled in this prospective single-center study. Sixteen of the patients had renal biopsy (mean 150 days) before the MRI. All patients underwent mpMRI at 1.5T including intravoxel-incoherent motion diffusion-weighted imaging, diffusion tensor imaging, blood oxygen level dependent (BOLD R2*) and T1 quantification. True diffusion D, pseudodiffusion D*, perfusion fraction PF, apparent diffusion coefficient (ADC), fractional anisotropy (FA), R2* and T1 were calculated for cortex and medulla. ΔT1 was calculated as (100x(T1 Cortex-T1 Medulla)/T1 Cortex). Test-retest repeatability and inter-observer reproducibility were assessed in four and ten patients, respectively. mpMRI parameters had substantial test-retest and interobserver repeatability (coefficient of variation under 15%), except for medullary PF and D* (coefficient of variation over 25%). Cortical ADC, D, medullary ADC and ΔT1 were all significantly decreased, while cortical T1 was significantly elevated in fibrotic allografts. Cortical T1 showed positive correlation to the Banff fibrosis and tubular atrophy scores. The combination of ΔT1 and cortical ADC had excellent cross-validated diagnostic performance for detection of chronic dysfunction with fibrosis. Cortical ADC and T1 had good performance for predicting eGFR decline at 18 months (4 or more ml/min/1.73m2/year). Thus, the combination of cortical ADC and T1 measurements shows promising results for the non-invasive assessment of renal allograft histology and outcomes.
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Affiliation(s)
- Octavia Bane
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Stefanie J Hectors
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | - Sonja Gordic
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Department of Radiology, University Hospital Zürich, Zürich, Switzerland
| | - Paul Kennedy
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Mathilde Wagner
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Amanda Weiss
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Rafael Khaim
- Division of Nephrology and Recanati Miller Transplantation Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Zhengzi Yi
- Division of Nephrology and Recanati Miller Transplantation Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Mount Sinai Center for Bioinformatics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Weijia Zhang
- Division of Nephrology and Recanati Miller Transplantation Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Mount Sinai Center for Bioinformatics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Veronica Delaney
- Mount Sinai Center for Bioinformatics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Fadi Salem
- Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Cijiang He
- Division of Nephrology and Recanati Miller Transplantation Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Madhav C Menon
- Division of Nephrology and Recanati Miller Transplantation Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Sara Lewis
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Bachir Taouli
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
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Sussman MS, Wintersperger BJ. Modified look-locker inversion recovery (MOLLI) T 1 mapping with inversion group (IG) fitting - A method for improved precision. Magn Reson Imaging 2019; 62:38-45. [PMID: 31170429 DOI: 10.1016/j.mri.2019.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 05/31/2019] [Accepted: 06/02/2019] [Indexed: 11/17/2022]
Abstract
MOLLI-based T1 mapping has been applied to a variety of cardiac pathologies. However, conventional MOLLI's requirement for rest periods between inversion groups increases scan time, and limits the choice of inversion groups. The recently developed inversion group (IG) fitting technique eliminates the rest period requirement, and permits complete flexibility of inversion groups. However, a limitation is that its T1 maps have low precision - up to 30% poorer than conventional 3-parameter methods. In the original IG method, T1 maps were derived from the first inversion group only. In the present study, a technique is presented which utilize data from all inversion groups to generate T1 maps. It is hypothesized this "composite-IG" fitting method will provided improved prevision over conventional-IG T1 mapping methods. Simulations, phantom, and in vivo experiments on nine clinical cardiac patients (congenital heart disease, ischemic- and non-ischemic cardiomyopathy) were performed. Imaging was performed on a 1.5 T Siemens scanner. Myocardial T1 mapping precision and reproducibility were calculated for conventional-IG, composite-IG, and 3-parameter techniques. Precision and reproducibility between the techniques was compared using the Wilcoxon Signed Rank test. Statistical significance was set at the 95% confidence level, with the Bonferroni correction for multiple comparisons employed. Composite-IG improves precision by 16-38% over conventional-IG (p < 0.01). Composite-IG T1 maps provided up to 5% better precision than 3-parameter fits (p < 0.01). Composite-IG had better reproducibility than conventional-IG (p < 0.01). However, there was no significant difference between composite-IG and conventional 5(3)3 3-parameter reproducibility.
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Affiliation(s)
- Marshall S Sussman
- Joint Department of Medical Imaging, University Health Network, University, Toronto, Ontario, Canada; Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.
| | - Bernd J Wintersperger
- Joint Department of Medical Imaging, University Health Network, University, Toronto, Ontario, Canada; Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.
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8
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Cho A, Eskandari R, Miloushev VZ, Keshari KR. A non-synthetic approach to extending the lifetime of hyperpolarized molecules using D 2O solvation. J Magn Reson 2018; 295:57-62. [PMID: 30099234 PMCID: PMC6131049 DOI: 10.1016/j.jmr.2018.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 07/31/2018] [Accepted: 08/01/2018] [Indexed: 06/08/2023]
Abstract
Although dissolution dynamic nuclear polarization is a robust technique to significantly increase magnetic resonance signal, the short T1 relaxation time of most 13C-nuclei limits the timescale of hyperpolarized experiments. To address this issue, we have characterized a non-synthetic approach to extend the hyperpolarized lifetime of 13C-nuclei in close proximity to solvent-exchangeable protons. Protons exhibit stronger dipolar relaxation than deuterium, so dissolving these compounds in D2O to exchange labile protons with solvating deuterons results in longer-lived hyperpolarization of the 13C-nucleus 2-bonds away. 13C T1 and T2 times were longer in D2O versus H2O for all molecules in this study. This phenomenon can be utilized to improve hyperpolarized signal-to-noise ratio as a function of longer T1, and enhanced spectral and imaging resolution via longer T2.
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Affiliation(s)
- Andrew Cho
- Department of Biochemistry & Structural Biology, Weill Cornell Graduate School, New York City, NY 10065, United States; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York City, NY 10065, United States.
| | - Roozbeh Eskandari
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York City, NY 10065, United States.
| | - Vesselin Z Miloushev
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York City, NY 10065, United States.
| | - Kayvan R Keshari
- Department of Biochemistry & Structural Biology, Weill Cornell Graduate School, New York City, NY 10065, United States; Department of Radiology, Memorial Sloan Kettering Cancer Center, New York City, NY 10065, United States; Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York City, NY 10065, United States.
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9
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Boillat Y, Bazin PL, O'Brien K, Fartaria MJ, Bonnier G, Krueger G, van der Zwaag W, Granziera C. Surface-based characteristics of the cerebellar cortex visualized with ultra-high field MRI. Neuroimage 2018; 172:1-8. [PMID: 29339314 DOI: 10.1016/j.neuroimage.2018.01.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 01/04/2018] [Accepted: 01/07/2018] [Indexed: 12/23/2022] Open
Abstract
Although having a relatively homogeneous cytoarchitectonic organization, the cerebellar cortex is a heterogeneous region characterized by different amounts of myelin, iron and protein expression profiles. In this study, we used quantitative T1 and T2* mapping at ultra-high field (7T) MRI to investigate the tissue characteristics of the cerebellar gray matter surface and its layers. Detailed subject-specific surfaces were generated at three different cortical depths and averaged across subjects to create averaged T1- and T2*-maps on the cerebellar surface. T1 surfaces showed an alternation of lower and higher T1 values when going from the median to the lateral part of the cerebellar hemispheres. In addition, longer T1 values were observed in the more superficial gray matter layers. T2*-maps showed a similar longitudinal pattern, but no change related to the cortical depths. These patterns are possibly due to variations in the level of myelination, iron and zebrin protein expression.
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Affiliation(s)
- Yohan Boillat
- Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
| | - Pierre-Louis Bazin
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Kieran O'Brien
- Siemens Healthcare Pty Ltd., Bowen Hills, Australia; Centre for Advanced Imaging, University of Queensland, Australia
| | - Mário João Fartaria
- Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland; Advanced Clinical Imaging Technology (ACIT, HC CEMEA SUI DI BM PI), Siemens Healthcare AG, Lausanne, Switzerland
| | - Guillaume Bonnier
- A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Gunnar Krueger
- Siemens Medical Solutions USA IM MR COL NEZ, Burlington, MA, USA
| | - Wietske van der Zwaag
- Biomedical Imaging Research Center, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Spinoza Centre for Neuroimaging, Amsterdam, Switzerland
| | - Cristina Granziera
- A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA; Neurology, Department of Clinical Neurosciences, CHUV and University of Lausanne, Netherlands
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10
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Cordes D, Yang Z, Zhuang X, Sreenivasan K, Mishra V, Hua LH. A new algebraic method for quantitative proton density mapping using multi-channel coil data. Med Image Anal 2017; 40:154-171. [PMID: 28668358 DOI: 10.1016/j.media.2017.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/06/2017] [Accepted: 06/15/2017] [Indexed: 11/30/2022]
Abstract
A difficult problem in quantitative MRI is the accurate determination of the proton density, which is an important quantity in measuring brain tissue organization. Recent progress in estimating proton density in vivo has been based on using the inverse linear relationship between the longitudinal relaxation rate T1 and proton density. In this study, the same type of relationship is being used, however, in a more general framework by constructing 3D basis functions to model the receiver bias field. The novelty of this method is that the basis functions developed are suitable to cover an entire range of inverse linearities between T1 and proton density. The method is applied by parcellating the human brain into small cubes with size 30mm x 30mm x 30mm. In each cube the optimal set of basis functions is determined to model the receiver coil sensitivities using multi-channel (32 element) coil data. For validation, we use arbitrary data from a numerical phantom where the data satisfy the conventional MR signal equations. Using added noise of different magnitude and realizations, we show that the proton densities obtained have a bias close to zero and also low noise sensitivity. The obtained root-mean-square-error rate is less than 0.2% for the estimated proton density in a realistic 3D simulation. As an application, the method is used in a small cohort of MS patients, and proton density values for specific brain structures are determined.
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Affiliation(s)
- Dietmar Cordes
- Cleveland Clinic Lou Ruvo Center for Brain Health, 888W. Bonneville Ave, Las Vegas, NV 89106, USA; University of Colorado, Boulder, CO, USA.
| | - Zhengshi Yang
- Cleveland Clinic Lou Ruvo Center for Brain Health, 888W. Bonneville Ave, Las Vegas, NV 89106, USA
| | - Xiaowei Zhuang
- Cleveland Clinic Lou Ruvo Center for Brain Health, 888W. Bonneville Ave, Las Vegas, NV 89106, USA
| | - Karthik Sreenivasan
- Cleveland Clinic Lou Ruvo Center for Brain Health, 888W. Bonneville Ave, Las Vegas, NV 89106, USA
| | - Virendra Mishra
- Cleveland Clinic Lou Ruvo Center for Brain Health, 888W. Bonneville Ave, Las Vegas, NV 89106, USA
| | - Le H Hua
- Cleveland Clinic Lou Ruvo Center for Brain Health, 888W. Bonneville Ave, Las Vegas, NV 89106, USA
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11
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Williamson NH, Röding M, Galvosas P, Miklavcic SJ, Nydén M. Obtaining T1-T2 distribution functions from 1-dimensional T1 and T2 measurements: The pseudo 2-D relaxation model. J Magn Reson 2016; 269:186-195. [PMID: 27344611 DOI: 10.1016/j.jmr.2016.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/14/2016] [Accepted: 06/15/2016] [Indexed: 06/06/2023]
Abstract
We present the pseudo 2-D relaxation model (P2DRM), a method to estimate multidimensional probability distributions of material parameters from independent 1-D measurements. We illustrate its use on 1-D T1 and T2 relaxation measurements of saturated rock and evaluate it on both simulated and experimental T1-T2 correlation measurement data sets. Results were in excellent agreement with the actual, known 2-D distribution in the case of the simulated data set. In both the simulated and experimental case, the functional relationships between T1 and T2 were in good agreement with the T1-T2 correlation maps from the 2-D inverse Laplace transform of the full 2-D data sets. When a 1-D CPMG experiment is combined with a rapid T1 measurement, the P2DRM provides a double-shot method for obtaining a T1-T2 relationship, with significantly decreased experimental time in comparison to the full T1-T2 correlation measurement.
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Affiliation(s)
- Nathan H Williamson
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
| | - Magnus Röding
- SP Food and Bioscience, Frans Perssons väg 6, 402 29 Göteborg, Sweden; School of Energy and Resources, UCL Australia, University College London, 220 Victoria Square, Adelaide, SA 5000, Australia.
| | - Petrik Galvosas
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand.
| | - Stanley J Miklavcic
- Phenomics and Bioinformatics Research Centre, School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA 5095, Australia.
| | - Magnus Nydén
- School of Energy and Resources, UCL Australia, University College London, 220 Victoria Square, Adelaide, SA 5000, Australia.
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12
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De Santis S, Assaf Y, Jeurissen B, Jones DK, Roebroeck A. T1 relaxometry of crossing fibres in the human brain. Neuroimage 2016; 141:133-142. [PMID: 27444568 PMCID: PMC5035137 DOI: 10.1016/j.neuroimage.2016.07.037] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/13/2016] [Accepted: 07/15/2016] [Indexed: 12/13/2022] Open
Abstract
A comprehensive tract-based characterisation of white matter should include the ability to quantify myelin and axonal attributes irrespective of the complexity of fibre organisation within the voxel. Recently, a new experimental framework that combines inversion recovery and diffusion MRI, called inversion recovery diffusion tensor imaging (IR-DTI), was introduced and applied in an animal study. IR-DTI provides the ability to assign to each unique fibre population within a voxel a specific value of the longitudinal relaxation time, T1, which is a proxy for myelin content. Here, we apply the IR-DTI approach to the human brain in vivo on 7 healthy subjects for the first time. We demonstrate that the approach is able to measure differential tract properties in crossing fibre areas, reflecting the different myelination of tracts. We also show that tract-specific T1 has less inter-subject variability compared to conventional T1 in areas of crossing fibres, suggesting increased specificity to distinct fibre populations. Finally we show in simulations that changes in myelination selectively affecting one fibre bundle in crossing fibre areas can potentially be detected earlier using IR-DTI. We apply the inversion recovery DTI approach to the human brain in vivo for the first time. We demonstrate that IR-DTI can measure tract-specific T1 in crossing fibres. IR-DTI T1 has less inter-subject variability compared to conventional T1 in crossing fibres. Changes in myelination affecting one fibre in crossing fibres can be detected earlier using IR-DTI.
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Affiliation(s)
- Silvia De Santis
- CUBRIC, School of Psychology, Cardiff University, Cardiff CF24 4HQ,UK; Maastricht University, Maastricht, The Netherlands.
| | - Yaniv Assaf
- Department of Neurobiology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ben Jeurissen
- iMinds-Vision Lab, Dept. of Physics, University of Antwerp, Antwerp, Belgium
| | - Derek K Jones
- CUBRIC, School of Psychology, Cardiff University, Cardiff CF24 4HQ,UK; Neuroscience & Mental Health Research Institute, Cardiff University, CF10 3AT,UK
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13
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Muir ER, Cardenas DP, Duong TQ. MRI of brain tissue oxygen tension under hyperbaric conditions. Neuroimage 2016; 133:498-503. [PMID: 27033683 DOI: 10.1016/j.neuroimage.2016.03.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 11/19/2022] Open
Abstract
The brain depends on a continuous supply of oxygen to maintain its structural and functional integrity. This study measured T1 from MRI under normobaric air, normobaric oxygen, hyperbaric air, and hyperbaric oxygen (HBO) conditions as a marker of tissue pO2 since dissolved molecular oxygen acts as an endogenous contrast agent. Brain tissue T1 decreased corresponding to increased pO2 with increasing inhaled oxygen concentrations, and tissue oxygenation was estimated from the T1 changes between different inhaled oxygen levels. Tissue pO2 difference maps between different oxygen conditions showed heterogeneous pO2 changes in the brain. MRI-derived tissue pO2 was markedly lower than the arterial pO2 but was slightly higher than venous pO2. Additionally, for comparison with published extracellular tissue pO2 data obtained using oxygen electrodes and other invasive techniques, a model was used to estimate extracellular and intracellular pO2 from the MRI-derived mean tissue pO2. This required multiple assumptions, and so the effects of the assumptions and parameters used in modeling brain pO2 were evaluated. MRI-derived pO2 values were strongly dependent on assumptions about the extra- and intracellular compartments but were relatively less sensitive to variations in the relaxivity constant of oxygen and contribution from oxygen in the cerebral blood compartment. This approach may prove useful in evaluating tissue oxygenation in disease states such as stroke.
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Affiliation(s)
- Eric R Muir
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States; Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, United States.
| | - Damon P Cardenas
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States; Graduate School of Biomedical Science, University of Texas at San Antonio, San Antonio, TX, United States
| | - Timothy Q Duong
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States; Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, United States; South Texas Veterans Health Care System, Department of Veterans Affairs, San Antonio, TX, United States.
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14
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Yesinowski JP. Finding the true spin-lattice relaxation time for half-integral nuclei with non-zero quadrupole couplings. J Magn Reson 2015; 252:135-144. [PMID: 25700115 DOI: 10.1016/j.jmr.2014.12.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 12/17/2014] [Accepted: 12/23/2014] [Indexed: 06/04/2023]
Abstract
Measuring true spin-lattice relaxation times T(1) of half-integral quadrupolar nuclei having non-zero nuclear quadrupole coupling constants (NQCCs) presents challenges due to the presence of satellite-transitions (STs) that may lie outside the excitation bandwidth of the central transition (CT). This leads to complications in establishing well-defined initial conditions for the population differences in these multi-level systems. In addition, experiments involving magic-angle spinning (MAS) can introduce spin exchange due to zero-crossings of the ST and CT (or possibly rotational resonance recoupling in the case of multiple sites) and greatly altered initial conditions as well. An extensive comparison of pulse sequences that have been previously used to measure T(1) in such systems is reported, using the (71)Ga (I=3/2) NMR of a Ge-doped h-GaN n-type semiconductor sample as the test case. The T(1) values were measured at the peak maximum of the Knight shift distribution. Analytical expressions for magnetization-recovery of the CT appropriate to the pulse sequences tested were used, involving contributions from both a magnetic relaxation mechanism (rate constant W) and a quadrupolar one (rate constants W(1) and W(2), approximately equal in this case). An asynchronous train of high-power saturating pulses under MAS that is able to completely saturate both CT and STs is found to be the most reliable and accurate method for obtaining the "true T(1)", defined here as (2W+2W1,2)(-)(1). All other methods studied yielded poor agreement with this "true T(1)" value or even resulted in gross errors, for reasons that are analyzed in detail. These methods involved a synchronous train of saturating pulses under MAS, an inversion-recovery sequence under MAS or static conditions, and a saturating comb of pulses on a static sample. Although the present results were obtained on a sample where the magnetic relaxation mechanism dominated the quadrupolar one, the asynchronous saturating pulse train approach is not limited to this situation. The extent to which W(1) and W(2) are unequal does affect the interpretability of the experiment however, particularly when the quadrupolar mechanism dominates. A numerically approximate solution for the I=3/2 recovery case reveals the quantitative effects of any such inequality.
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Affiliation(s)
- James P Yesinowski
- Chemistry Division, Naval Research Laboratory, Washington, DC 20375-5342, USA.
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15
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Castañar L, Nolis P, Virgili A, Parella T. Measurement of T₁/T₂ relaxation times in overlapped regions from homodecoupled ¹H singlet signals. J Magn Reson 2014; 244:30-35. [PMID: 24833611 DOI: 10.1016/j.jmr.2014.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/02/2014] [Accepted: 04/06/2014] [Indexed: 06/03/2023]
Abstract
The implementation of the HOmodecoupled Band-Selective (HOBS) technique in the conventional Inversion-Recovery and CPMG-based PROJECT experiments is described. The achievement of fully homodecoupled signals allows the distinction of overlapped (1)H resonances with small chemical shift differences. It is shown that the corresponding T1 and T2 relaxation times can be individually measured from the resulting singlet lines using conventional exponential curve-fitting methods.
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Affiliation(s)
- Laura Castañar
- Servei de Ressonància Magnètica Nuclear and Departament de Química, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain
| | - Pau Nolis
- Servei de Ressonància Magnètica Nuclear and Departament de Química, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain
| | - Albert Virgili
- Servei de Ressonància Magnètica Nuclear and Departament de Química, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear and Departament de Química, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain.
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Kadayakkara DK, Damodaran K, Hitchens TK, Bulte JWM, Ahrens ET. (19)F spin-lattice relaxation of perfluoropolyethers: Dependence on temperature and magnetic field strength (7.0-14.1T). J Magn Reson 2014; 242:18-22. [PMID: 24594752 PMCID: PMC4008704 DOI: 10.1016/j.jmr.2014.01.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Revised: 01/28/2014] [Accepted: 01/30/2014] [Indexed: 06/03/2023]
Abstract
Fluorine ((19)F) MRI of perfluorocarbon-labeled cells has become a powerful technique to track the migration and accumulation of cells in living organisms. It is common to label cells for (19)F MRI with nanoemulsions of perfluoropolyethers that contain a large number of chemically equivalent fluorine atoms. Understanding the mechanisms of (19)F nuclear relaxation, and in particular the spin-lattice relaxation of these molecules, is critical to improving experimental sensitivity. To date, the temperature and magnetic field strength dependence of spin-lattice relaxation rate constant (R1) for perfluoropolyethers has not been described in detail. In this study, we evaluated the R1 of linear perfluoropolyether (PFPE) and cyclic perfluoro-15-crown-5 ether (PCE) at three magnetic field strengths (7.0, 9.4, and 14.1T) and at temperatures ranging from 256-323K. Our results show that R1 of perfluoropolyethers is dominated by dipole-dipole interactions and chemical shift anisotropy. R1 increased with magnetic field strength for both PCE and PFPE. In the temperature range studied, PCE was in the fast motion regime (ωτc<1) at all field strengths, but for PFPE, R1 passed through a maximum, from which the rotational correlation time was estimated. The importance of these measurements for the rational design of new (19)F MRI agents and methods is discussed.
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Affiliation(s)
- Deepak K Kadayakkara
- Russell H. Morgan Dept. of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Dept. of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Cellular Imaging Section, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Krishnan Damodaran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - T Kevin Hitchens
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Pittsburgh NMR Center for Biomedical Research, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Jeff W M Bulte
- Russell H. Morgan Dept. of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Dept. of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Dept. of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Dept. of Chemical & Biomolecular Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Cellular Imaging Section, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Eric T Ahrens
- Department of Radiology, University of California at San Diego, La Jolla, CA 92093, USA
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Towner RA, Smith N, Saunders D, Lupu F, Silasi-Mansat R, West M, Ramirez DC, Gomez-Mejiba SE, Bonini MG, Mason RP, Ehrenshaft M, Hensley K. In vivo detection of free radicals using molecular MRI and immuno-spin trapping in a mouse model for amyotrophic lateral sclerosis. Free Radic Biol Med 2013; 63:351-60. [PMID: 23722162 DOI: 10.1016/j.freeradbiomed.2013.05.026] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 05/13/2013] [Accepted: 05/17/2013] [Indexed: 11/19/2022]
Abstract
Free radicals associated with oxidative stress play a major role in amyotrophic lateral sclerosis (ALS). By combining immuno-spin trapping and molecular magnetic resonance imaging, in vivo trapped radical adducts were detected in the spinal cords of SOD1(G93A)-transgenic (Tg) mice, a model for ALS. For this study, the nitrone spin trap DMPO (5,5-dimethyl-1-pyrroline N-oxide) was administered (ip) over 5 days before administration (iv) of an anti-DMPO probe (anti-DMPO antibody covalently bound to an albumin-gadolinium-diethylenetriamine pentaacetic acid-biotin MRI contrast agent) to trap free radicals. MRI was used to detect the presence of the anti-DMPO radical adducts by a significant sustained increase in MR signal intensities (p < 0.05) or anti-DMPO probe concentrations measured from T₁ relaxations (p < 0.01). The biotin moiety of the anti-DMPO probe was targeted with fluorescence-labeled streptavidin to locate the probe in excised tissues. Negative controls included either Tg ALS mice initially administered saline rather than DMPO followed by the anti-DMPO probe or non-Tg mice initially administered DMPO and then the anti-DMPO probe. The anti-DMPO probe was found to bind to neurons via colocalization fluorescence microscopy. DMPO adducts were also confirmed in diseased/nondiseased tissues from animals administered DMPO. Apparent diffusion coefficients from diffusion-weighted images of spinal cords from Tg mice were significantly elevated (p < 0.001) compared to wild-type controls. This is the first report regarding the detection of in vivo trapped radical adducts in an ALS model. This novel, noninvasive, in vivo diagnostic method can be applied to investigate the involvement of free radical mechanisms in ALS rodent models.
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Affiliation(s)
- Rheal A Towner
- Advanced Magnetic Resonance Center, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
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Tomasi C, Corsi C, Turco D, Severi S. An exploratory study on coronary sinus lead tip three-dimensional trajectory changes in cardiac resynchronization therapy. Heart Rhythm 2013; 10:1360-7. [PMID: 23851066 DOI: 10.1016/j.hrthm.2013.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Indexed: 11/24/2022]
Abstract
BACKGROUND Prediction of response to cardiac resynchronization therapy (CRT) is still an unsolved major issue. The interface between left ventricular mechanics, coronary sinus (CS) lead, and pacing delivery has been little investigated. OBJECTIVE To investigate CS lead tip movements at baseline and during biventricular pacing (BiV) in the hypothesis that they could provide some insights into left ventricular mechanical behavior in CRT. METHODS Three-dimensional reconstruction of CS lead tip trajectory throughout the cardiac cycle using a novel fluoroscopy-based method was performed in 22 patients with chronic heart failure (19 men; mean age 70 ± 10 years). Three trajectories were computed: before (T-1) and immediately after (T0) BiV start-up and after 6 months (T1). CRT response was the echocardiographic end-systolic volume reduction ≥15% at T1. Metrics describing trajectory at T0, T-1, and T1 were compared between 9 responders (R) and 13 nonresponders (NR). RESULTS At T-1 trajectories demonstrated heterogeneous shapes and metrics, but at T0 the variations in the ratio between the two main axes (S1/S2) and in the eccentricity were statistically different between R and NR, pointing out a trajectory's change toward a significantly more circular shape at BiV start-up in R. Remarkably, R and NR could be completely separated by means of the percent variation in S1/S2 from T-1 to T0 (R: 47.5% [31.5% to 54.1%] vs. NR: -25.6% [-67% to -6.5%]). This single marker computed at T0 would have predicted CRT response at T1. CONCLUSIONS Preliminary data showed that CS lead tip trajectory changes induced by BiV were related to mechanical resynchronization.
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