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Gul MR, Ince AE, Ozel B, Uslu AK, Çetin M, Mentes D, Sumnu SG, Oztop MH. Effect of microwave-vacuum drying on the physicochemical properties of a functional tomato snack bar. J Sci Food Agric 2024; 104:83-92. [PMID: 37566724 DOI: 10.1002/jsfa.12894] [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] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 07/24/2023] [Accepted: 08/11/2023] [Indexed: 08/13/2023]
Abstract
BACKGROUND Tomato is an indispensable ingredient of the Mediterranean diet. Reformulation of traditional Mediterranean products to increase the adherence of consumers is becoming popular. In this study, a tomato snack bar enriched with olive powder and pea protein was developed by using microwave-vacuum drying. Formulations also included tomato powder (TP) and low-methoxylated pectin (LMP) as a structuring agent. RESULTS The moisture content of microwave-vacuum-dried samples varied in the range 13.6-19.8% and water activity (aw ) values were ~0.6. LMP and TP concentrations affected the color of microwave-vacuum-dried samples. However, the color mainly changed in conventionally dried samples due to browning. In microwave-vacuum-dried samples, lycopene content decreased with increasing LMP, but increased with increasing TP. Textural properties of microwave-vacuum-dried snack bars increased with increasing LMP and TP. CONCLUSION Both texture and Fourier transform infrared spectroscopy results indicated that there was a network formation due to the contribution of protein and pectin; however, the type of interaction was highly dependent on the drying mechanism. Nuclear magnetic resonance relaxometry data showed that microwave-vacuum-dried samples had a more uniform water distribution. Besides its time and energy efficiency, microwave-vacuum drying improved the color and textural properties of tomato snack bars compared to conventionally dried ones. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Muhammed Rasim Gul
- Department of Food Engineering, Middle East Technical University, Ankara, Turkey
| | - Alev Emine Ince
- Department of Food Engineering, Middle East Technical University, Ankara, Turkey
- Food Processing Department, Kahramankazan Vocational School, Baskent University, Ankara, Turkey
| | - Baris Ozel
- Department of Food Engineering, Middle East Technical University, Ankara, Turkey
- Department of Food Engineering, Ahi Evran University, Kirsehir, Turkey
| | - Aymelek Kubra Uslu
- Department of Food Engineering, Middle East Technical University, Ankara, Turkey
| | - Melis Çetin
- Department of Food Engineering, Middle East Technical University, Ankara, Turkey
| | - Duygu Mentes
- Department of Food Engineering, Middle East Technical University, Ankara, Turkey
| | - Servet Gulum Sumnu
- Department of Food Engineering, Middle East Technical University, Ankara, Turkey
| | - Mecit Halil Oztop
- Department of Food Engineering, Middle East Technical University, Ankara, Turkey
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2
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Kleban E, Jones DK, Tax CM. The impact of head orientation with respect to B 0 on diffusion tensor MRI measures. Imaging Neurosci (Camb) 2023; 1:1-17. [PMID: 38405373 PMCID: PMC10884544 DOI: 10.1162/imag_a_00012] [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] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 07/27/2023] [Indexed: 02/27/2024]
Abstract
Diffusion tensor MRI (DT-MRI) remains the most commonly used approach to characterise white matter (WM) anisotropy. However, DT estimates may be affected by tissue orientation w.r.t. B → 0 due to local gradients and intrinsic T 2 orientation dependence induced by the microstructure. This work aimed to investigate whether and how diffusion tensor MRI-derived measures depend on the orientation of the head with respect to the static magnetic field, B → 0 . By simulating WM as two compartments, we demonstrated that compartmental T 2 anisotropy can induce the dependence of diffusion tensor measures on the angle between WM fibres and the magnetic field. In in vivo experiments, reduced radial diffusivity and increased axial diffusivity were observed in white matter fibres perpendicular to B → 0 compared to those parallel to B → 0 . Fractional anisotropy varied by up to 20 % as a function of the angle between WM fibres and the orientation of the main magnetic field. To conclude, fibre orientation w.r.t. B → 0 is responsible for up to 7 % variance in diffusion tensor measures across the whole brain white matter from all subjects and head orientations. Fibre orientation w.r.t. B → 0 may introduce additional variance in clinical research studies using diffusion tensor imaging, particularly when it is difficult to control for (e.g., fetal or neonatal imaging, or when the trajectories of fibres change due to, e.g., space occupying lesions).
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Affiliation(s)
- Elena Kleban
- CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom
- Inselspital, University of Bern, Bern, Switzerland
| | - Derek K. Jones
- CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom
- MMIHR, Faculty of Health Sciences, Australian Catholic University, Melbourne, Australia
| | - Chantal M.W. Tax
- CUBRIC, School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
- UMC Utrecht, Utrecht University, Utrecht, The Netherlands
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3
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Nosrati R, Balasubramanian M, Mulkern R. Measuring transverse relaxation rates of the major brain metabolites from single-voxel PRESS acquisitions at a single TE. Magn Reson Med 2021; 85:2965-2977. [PMID: 33404069 DOI: 10.1002/mrm.28644] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/21/2020] [Accepted: 11/24/2020] [Indexed: 11/08/2022]
Abstract
PURPOSE To compare transverse relaxation rates of brain metabolites estimated from single-TE PRESS acquisitions with more conventionally derived rates estimated from multiple-TE PRESS acquisitions. METHODS Single-voxel (8 mL) PRESS data within white matter from 6 subjects were acquired at five different TEs. Transverse relaxation rates R2 of N-acetylaspartate, creatine, and choline were estimated from a single TE using full versus right-side-only sampling of the echo. These R2 values were compared with R2Hahn values obtained from the multiple-TE PRESS acquisitions. RESULTS Following baseline subtraction and RMS weighting, interindividual mean R2 values from TE = 288 ms magnitude spectra for choline, creatine, and N-acetylaspartate were highly correlated with respective R2Hahn values (r2 = 0.99). Paired individual measurements at this TE showed less correlation (r2 = 0.48), primarily due to the N-acetylaspartate resonance. Using TE = 360 ms data for N-acetylaspartate and 288 ms for choline and creatine resulted in an improved correlation coefficient (r2 = 0.80). The average absolute intra-individual differences in the estimated R2 s between single-TE and Hahn method was 9.6 ± 7.7%. CONCLUSION For the major brain metabolite singlets, R2Hahn values showed correlations with more fragile measurements of R2 from a single TE that are worthy of interest. Because the left side of long-TE spin echoes is available "for free" from an acquisition perspective, and although the single-TE method for estimating R2 values is associated with lower precision, the reduction in scan time may be clinically helpful.
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Affiliation(s)
- Reyhaneh Nosrati
- Radiology Department, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Mukund Balasubramanian
- Radiology Department, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Robert Mulkern
- Radiology Department, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
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4
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Lee H, Wehrli FW. Alternating unbalanced SSFP for 3D R 2 ' mapping of the human brain. Magn Reson Med 2020; 85:2391-2402. [PMID: 33331076 DOI: 10.1002/mrm.28637] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/11/2020] [Accepted: 11/16/2020] [Indexed: 11/10/2022]
Abstract
PURPOSE Measuring the transverse-relaxation rate R 2 ' provides valuable information in quantitative evaluation of tissue microstructure, for example, in terms of oxygenation levels. Here, we propose an alternating unbalanced SSFP pulse sequence for rapid whole-brain 3D R 2 ' mapping. METHODS Unlike currently practiced, spin echo-based R 2 ' measurement techniques, the proposed method alternates between SSFP-FID and SSFP-ECHO modes for rapid 3D encoding of transverse relaxation rates expressed as R2 + R 2 ' and R2 - R 2 ' . Z-shimming gradients embedded into multi-echo trains of each SSFP module are designed to achieve relative immunity to large-scale magnetic-field variations (ΔB0 ). Appropriate models for the temporal evolution of the two groups of SSFP signals were constructed with ΔB0 -induced modulations accounted for, leading to ΔB0 -corrected estimation of R2 , R 2 ' , and R 2 ∗ (= R2 + R 2 ' ). Additionally, relative magnetic susceptibility (Δχ) maps were obtained by quantitative susceptibility mapping of the phase data. Numerical simulations were performed to optimize scan parameters, followed by in vivo studies at 3 T in 7 healthy subjects. Measured parameters were evaluated in six brain regions, and subjected to interparameter correlation analysis. RESULTS The resultant maps of R 2 ' and additionally derived R2 , R 2 ∗ , and Δχ all demonstrated the expected contrast across brain territories (eg, deep brain structures versus cortex), with the measured values in good agreement with previous reports. Furthermore, regression analyses yielded strong linear relationships for the transverse relaxation parameters ( R 2 ' , R2 , and R 2 ∗ ) against Δχ. CONCLUSION Results suggest feasibility of the proposed method as a practical and reliable means for measuring R 2 ' , R2 , R 2 ∗ , and Δχ across the entire brain.
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Affiliation(s)
- Hyunyeol Lee
- Laboratory for Structural, Physiologic, and Functional Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Felix W Wehrli
- Laboratory for Structural, Physiologic, and Functional Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Patzig F, Mildner T, Schlumm T, Müller R, Möller HE. Deconvolution-based distortion correction of EPI using analytic single-voxel point-spread functions. Magn Reson Med 2020; 85:2445-2461. [PMID: 33220010 DOI: 10.1002/mrm.28591] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 10/19/2020] [Accepted: 10/19/2020] [Indexed: 11/11/2022]
Abstract
PURPOSE To develop a postprocessing algorithm that corrects geometric distortions due to spatial variations of the static magnetic field amplitude, B0 , and effects from relaxation during signal acquisition in EPI. THEORY AND METHODS An analytic, complex point-spread function is deduced for k-space trajectories of EPI variants and applied to corresponding acquisitions in a resolution phantom and in human volunteers at 3 T. With the analytic point-spread function and experimental maps of B0 (and, optionally, the effective transverse relaxation time, T 2 * ) as input, a point-spread function matrix operator is devised for distortion correction by a Thikonov-regularized deconvolution in image space. The point-spread function operator provides additional information for an appropriate correction of the signal intensity distribution. A previous image combination algorithm for acquisitions with opposite phase blip polarities is adapted to the proposed method to recover destructively interfering signal contributions. RESULTS Applications of the proposed deconvolution-based distortion correction ("DecoDisCo") algorithm demonstrate excellent distortion corrections and superior performance regarding the recovery of an undistorted intensity distribution in comparison to a multifrequency reconstruction. Examples include full and partial Fourier standard EPI scans as well as double-shot center-out trajectories. Compared with other distortion-correction approaches, DecoDisCo permits additional deblurring to obtain sharper images in cases of significant T 2 * effects. CONCLUSION Robust distortion corrections in EPI acquisitions are feasible with high quality by regularized deconvolution with an analytic point-spread function. The general algorithm, which is publicly released on GitHub, can be straightforwardly adapted for specific EPI variants or other acquisition schemes.
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Affiliation(s)
- Franz Patzig
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Toralf Mildner
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Torsten Schlumm
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Roland Müller
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Harald E Möller
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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6
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Steidle G, Schick F. A new concept for improved quantitative analysis of reversible transverse relaxation in tissues with variable microscopic field distribution. Magn Reson Med 2020; 85:1493-1506. [PMID: 33000529 DOI: 10.1002/mrm.28534] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 09/03/2020] [Accepted: 09/03/2020] [Indexed: 12/12/2022]
Abstract
PURPOSE The intravoxel distribution of the magnetic field strongly influences signal dephasing after RF excitation and the resulting signal decay in gradient echo-based MRI. In this work, several different field distribution models were applied and tested for analysis of microscopic field characteristics within pixels. THEORY A flexible model for improved pixel-wise characterization of the underlying field distribution is introduced. The proposed symmetric alpha-stable (SαS) distribution covers Lorentzian, Gaussian, and intermediate field distributions in a continuous way using a two-parametric (width and shape) function. METHODS The new model was applied on human brain, potatoes (homogeneous isotropic tissue), and stems of pineapple (anisotropic fibrous tissue). Effects of microscopic structure and background gradients on the shape and the widths of the microscopic field distribution were analyzed using gradient echo sampling of the spin echo and multigradient-echo sequences. Effects of non-Lorentzian shapes of microscopic field distributions on the results of common T 2 ∗ measurements with mono-exponential fitting of signal values were tested. RESULTS Many pixels of the examined objects showed field characteristics in between Lorentzian and Gaussian shapes. Microscopic field inhomogeneities caused by microscopic susceptibility effects and background gradients sometimes led to rather Gaussian than Lorentzian field distribution. In cases with nearly Gaussian field distribution, mono-exponential fitting of the signal decay resulted in different T 2 ∗ values, depending on the sampling points. CONCLUSIONS Using the concept of more flexible distributions for characterization of microscopic susceptibility effects in tissue provides better fitting of data and nearly sampling point-independent results than common T 2 ∗ measurements with mono-exponential fitting.
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Affiliation(s)
- Günter Steidle
- Section of Experimental Radiology, Department of Diagnostic and Interventional Radiology, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Fritz Schick
- Section of Experimental Radiology, Department of Diagnostic and Interventional Radiology, Universitätsklinikum Tübingen, Tübingen, Germany
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7
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Mulkern RV, Nosrati R, Balasubramanian M. Spectrally-selective measurements of reversible and irreversible transverse relaxation rates from single spin-echo PRESS acquisitions in muscle. NMR Biomed 2020; 33:e4290. [PMID: 32167612 DOI: 10.1002/nbm.4290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 06/13/2019] [Revised: 02/18/2020] [Accepted: 02/22/2020] [Indexed: 06/10/2023]
Abstract
The goal of this study was to test a new formalism for extracting reversible and irreversible transverse relaxation rates from resonances within typical proton muscle spectra using only a single spin echo as acquired with routine single-voxel, point-resolved echo spectroscopy (PRESS) acquisitions. Single-voxel, non-water-suppressed PRESS acquisitions within the calf muscles of four healthy subjects were performed at 1.5 T using six echo times ranging from 30 to 576 ms. Novel transverse relaxation analyses of water, choline, creatine, and lipid resonances were performed based upon the disparate relaxation sensitivities of the left versus the right sides of spectroscopically sampled spin echoes. Irreversible and reversible transverse relaxation rates R2 and R2 ' were extracted for water, metabolites, and lipids using echo times of 288 ms and longer. The R2 values so obtained were compared with more conventional "gold standard" Hahn values, R2Hahn , evaluated from the echo-time dependence of spectral peak areas generated from right-side sampling alone. Water resonances displayed biexponential Hahn signal decays, consistent with observations of decreasing R2 values with increasing echo time via the new approach. Choline and creatine resonances displayed monoexponential echo-time decays, with R2Hahn values in reasonable agreement with R2 values obtained from the single-echo analyses at the longer echo times. Lipid methylene and methyl R2 values extracted from the new approach were also in reasonable accord with R2Hahn values. Further validation of the technique was provided through PRESS acquisitions on a water phantom to which various levels of gadolinium were added in order to manipulate transverse relaxation rates, yielding excellent agreement between water-resonance R2Hahn and single-echo R2 values. In summary, this work demonstrates the feasibility of measuring reversible and irreversible transverse relaxation rates for individual spectral peaks from single-echo PRESS acquisitions, enabling a reduction in overall scan time relative to the use of multiple acquisitions with varying echo time.
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Affiliation(s)
- Robert V Mulkern
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Reyhaneh Nosrati
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Mukund Balasubramanian
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
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8
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Farrher E, Grinberg F, Kuo LW, Cho KH, Buschbeck RP, Chen MJ, Chiang HH, Choi CH, Shah NJ. Dedicated diffusion phantoms for the investigation of free water elimination and mapping: insights into the influence of T 2 relaxation properties. NMR Biomed 2020; 33:e4210. [PMID: 31926122 DOI: 10.1002/nbm.4210] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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: 05/09/2018] [Revised: 09/16/2019] [Accepted: 10/11/2019] [Indexed: 06/10/2023]
Abstract
Conventional diffusion-weighted (DW) MRI suffers from free water contamination due to the finite voxel size. The most common case of free water contamination occurs with cerebrospinal fluid (CSF) in voxels located at the CSF-tissue interface, such as at the ventricles in the human brain. Another case refers to intra-tissue free water as in vasogenic oedema. In order to avoid the bias in diffusion metrics, several multi-compartment methods have been introduced, which explicitly model the presence of a free water compartment. However, fitting multi-compartment models in DW MRI represents a well known ill conditioned problem. Although during the last decade great effort has been devoted to mitigating this estimation problem, the research field remains active. The aim of this work is to introduce the design, characterise the NMR properties and demonstrate the use of two dedicated anisotropic diffusion fibre phantoms, useful for the study of free water elimination (FWE) and mapping models. In particular, we investigate the recently proposed FWE diffusion tensor imaging approach, which takes explicit account of differences in the transverse relaxation times between the free water and tissue compartments.
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Affiliation(s)
- Ezequiel Farrher
- Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich, Jülich, Germany
| | - Farida Grinberg
- Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich, Jülich, Germany
| | - Li-Wei Kuo
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
- Institute of Medical Device and Imaging, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Kuan-Hung Cho
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
| | - Richard P Buschbeck
- Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich, Jülich, Germany
| | - Ming-Jye Chen
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
| | - Husan-Han Chiang
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
| | - Chang-Hoon Choi
- Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich, Jülich, Germany
| | - N Jon Shah
- Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich, Jülich, Germany
- Department of Neurology, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
- JARA BRAIN Translational Medicine, RWTH Aachen University, Aachen, Germany
- Institute of Neuroscience and Medicine 11,JARA, Forschungszentrum Jülich, Jülich, Germany
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Kim J, Moestue SA, Bathen TF, Kim E. R2* Relaxation Affects Pharmacokinetic Analysis of Dynamic Contrast-Enhanced MRI in Cancer and Underestimates Treatment Response at 7 T. ACTA ACUST UNITED AC 2019; 5:308-319. [PMID: 31572792 PMCID: PMC6752293 DOI: 10.18383/j.tom.2019.00015] [Citation(s) in RCA: 4] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Effective transverse relaxivity of gadolinium-based contrast agents is often neglected in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Here, we assess time and tissue dependence of R2* enhancement and its impact on pharmacokinetic parameter quantification and treatment monitoring. Multiecho DCE-MRI was performed at 7 T on mice bearing subcutaneous TOV-21G human ovarian cancer xenografts (n = 8) and on the transgenic adenocarcinoma of the mouse prostate (TRAMP) model (n = 7). Subsequently, the TOV-21G tumor-bearing mice were treated with bevacizumab and rescanned 2 days later. Pharmacokinetic analysis (extended Tofts model) was performed using either the first echo signal only (standard single-echo DCE-MRI) or the estimated signal at TE = 0 derived from exponential fitting of R2* relaxation (R2*-corrected). Neglecting R2* enhancement causes underestimation of Gd-DOTA concentration (peak enhancement underestimated by 9.4%-16% in TOV-21G tumors and 13%-20% in TRAMP prostates). Median Ktrans and ve were underestimated in every mouse (TOV-21G Ktrans: 11%-19%, TOV-21G ve: 5.3%-8.9%; TRAMP Ktrans: 8.6%-19%, TRAMP ve: 12%-21%). Bevacizumab treatment reduced Ktrans in all TOV-21G tumors after 48 hours. Treatment effect was significantly greater in all tumors after R2* correction (median change of -0.050 min-1 in R2*-corrected Ktrans vs. -0.037 min-1 in uncorrected Ktrans). R2* enhancement in DCE-MRI is both time- and tissue-dependent and may not be negligible at 7 T in tissue with high Ktrans. This has consequences for the use of Ktrans and other DCE-MRI parameters as biomarkers, because treatment effect size can be underestimated when R2* enhancement is neglected.
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Affiliation(s)
- Jana Kim
- Department of Circulation and Medical Imaging, Faculty of Medicine, NTNU - Norwegian University of Science and Technology, Trondheim, Norway.,St. Olavs Hospital, Trondheim, Norway
| | - Siver A Moestue
- Department of Circulation and Medical Imaging, Faculty of Medicine, NTNU - Norwegian University of Science and Technology, Trondheim, Norway.,Department of Laboratory Medicine, Women's and Children's Health, NTNU - Norwegian University of Science and Technology, Trondheim, Norway.,Department of Pharmacy, Faculty of Health Sciences, Nord University, Namsos, Norway; and
| | - Tone F Bathen
- Department of Circulation and Medical Imaging, Faculty of Medicine, NTNU - Norwegian University of Science and Technology, Trondheim, Norway.,St. Olavs Hospital, Trondheim, Norway
| | - Eugene Kim
- Department of Circulation and Medical Imaging, Faculty of Medicine, NTNU - Norwegian University of Science and Technology, Trondheim, Norway.,Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, England
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10
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Berman AJL, Pike GB. Transverse signal decay under the weak field approximation: Theory and validation. Magn Reson Med 2017; 80:341-350. [PMID: 29194739 DOI: 10.1002/mrm.27035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [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: 09/01/2017] [Revised: 11/15/2017] [Accepted: 11/16/2017] [Indexed: 12/25/2022]
Abstract
PURPOSE To derive an expression for the transverse signal time course from systems in the motional narrowing regime, such as water diffusing in blood. This was validated in silico and experimentally with ex vivo blood samples. METHODS A closed-form solution (CFS) for transverse signal decay under any train of refocusing pulses was derived using the weak field approximation. The CFS was validated via simulations of water molecules diffusing in the presence of spherical perturbers, with a range of sizes and under various pulse sequences. The CFS was compared with more conventional fits assuming monoexponential decay, including chemical exchange, using ex vivo blood Carr-Purcell-Meiboom-Gill data. RESULTS From simulations, the CFS was shown to be valid in the motional narrowing regime and partially into the intermediate dephasing regime, with increased accuracy with increasing Carr-Purcell-Meiboom-Gill refocusing rate. In theoretical calculations of the CFS, fitting for the transverse relaxation rate (R2 ) gave excellent agreement with the weak field approximation expression for R2 for Carr-Purcell-Meiboom-Gill sequences, but diverged for free induction decay. These same results were confirmed in the ex vivo analysis. CONCLUSION Transverse signal decay in the motional narrowing regime can be accurately described analytically. This theory has applications in areas such as tissue iron imaging, relaxometry of blood, and contrast agent imaging. Magn Reson Med 80:341-350, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Avery J L Berman
- Department of Biomedical Engineering, McGill University, Montreal, Quebec, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - G Bruce Pike
- Department of Biomedical Engineering, McGill University, Montreal, Quebec, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Departments of Radiology and Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
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11
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Barrilero R, Ramírez N, Vallvé JC, Taverner D, Fuertes R, Amigó N, Correig X. Unravelling and Quantifying the "NMR-Invisible" Metabolites Interacting with Human Serum Albumin by Binding Competition and T2 Relaxation-Based Decomposition Analysis. J Proteome Res 2017; 16:1847-1856. [PMID: 28345344 DOI: 10.1021/acs.jproteome.6b00814] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantitative profiling of low-molecular-weight metabolites (LMWMs) by 1H NMR is routinely used in high-throughput serum metabolomics. First, the protein background is attenuated using a T2 filter; then, the LMWM signals are resolved by line-shape fitting. However, protein-binding modifies the motional properties of LMWM, and their signal partially attenuates with the T2 filter, along with the protein background. Consequently, the quantified LMWM signals do not reflect the total concentration in serum but the nonbinding part. Here we present a novel strategy based on binding competition to promote the release of the "NMR-invisible" metabolites from serum proteins and achieve quantifications closer to total concentrations. The study focuses on five clinically relevant amino acids with different binding properties (valine, isoleucine, leucine, tyrosine, and phenylalanine). We analyzed their binding affinity to human serum albumin (HSA) in serum mimic samples and promoted the release of their bound fraction by TSP titration. Furthermore, we used a novel combination of pseudo-2D CPMG and multivariate curve resolution analysis, allowing the separation of LMWM and protein signals and providing LMWM quantifications corrected for transverse relaxation effects. We found that TSP concentrations larger than 3 mM released most of the bound fraction and validated these findings in real serum/plasma samples.
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Affiliation(s)
- Ruben Barrilero
- Department of Electronic Engineering, Universitat Rovira i Virgili , Metabolomics Platform, URV, 43007 Tarragona, Spain.,Pere Virgili Health Research Institute, IISPV , 43204 Reus, Spain.,Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM) , 28029 Madrid, Spain
| | - Noelia Ramírez
- Department of Electronic Engineering, Universitat Rovira i Virgili , Metabolomics Platform, URV, 43007 Tarragona, Spain.,Pere Virgili Health Research Institute, IISPV , 43204 Reus, Spain.,Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM) , 28029 Madrid, Spain
| | - Joan Carles Vallvé
- Pere Virgili Health Research Institute, IISPV , 43204 Reus, Spain.,Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM) , 28029 Madrid, Spain.,Vascular Medicine and Metabolism Unit, Research Unit on Lipids and Atherosclerosis, Universitat Rovira i Virgili , 43201 Reus, Spain
| | - Delia Taverner
- Pere Virgili Health Research Institute, IISPV , 43204 Reus, Spain.,Vascular Medicine and Metabolism Unit, Research Unit on Lipids and Atherosclerosis, Universitat Rovira i Virgili , 43201 Reus, Spain.,Sant Joan University Hospital, Universitat Rovira i Virgili , 43204 Reus, Spain
| | - Rocío Fuertes
- Department of Electronic Engineering, Universitat Rovira i Virgili , Metabolomics Platform, URV, 43007 Tarragona, Spain.,Pere Virgili Health Research Institute, IISPV , 43204 Reus, Spain.,Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM) , 28029 Madrid, Spain.,Biosfer Teslab SL , 43201 Reus, Spain
| | - Núria Amigó
- Department of Electronic Engineering, Universitat Rovira i Virgili , Metabolomics Platform, URV, 43007 Tarragona, Spain.,Pere Virgili Health Research Institute, IISPV , 43204 Reus, Spain.,Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM) , 28029 Madrid, Spain.,Biosfer Teslab SL , 43201 Reus, Spain
| | - Xavier Correig
- Department of Electronic Engineering, Universitat Rovira i Virgili , Metabolomics Platform, URV, 43007 Tarragona, Spain.,Pere Virgili Health Research Institute, IISPV , 43204 Reus, Spain.,Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM) , 28029 Madrid, Spain
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12
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Abstract
This study aimed to determine whether measurements of cerebrovascular reserve and oxygenation, assessed with spin relaxation rate R2', yield similar information about pathology in pre-operative Moyamoya disease patients, and to assess whether R2' is a better measure of oxygenation than other proposed markers, such as R2* and R2. Twenty-five pre-operative Moyamoya disease patients were scanned at 3.0T with acetazolamide challenge. Cerebral blood flow mapping with multi-delay arterial spin labeling, and R2*, R2, and R2' mapping with Gradient-Echo Sampling of Free Induction Decay and Echo were performed. No baseline cerebral blood flow difference was found between angiographically abnormal and normal regions (49 ± 12 vs. 48 ± 11 mL/100 g/min, p = 0.44). However, baseline R2' differed between these regions (3.2 ± 0.7 vs. 2.9 ± 0.6 s-1, p < 0.001), indicating reduced oxygenation in abnormal regions. Cerebrovascular reserve was lower in angiographically abnormal regions (21 ± 38 vs. 41 ± 26%, p = 0.001). All regions showed trend toward significantly improved oxygenation post-acetazolamide. Regions with poorer cerebrovascular reserve had lower baseline oxygenation (Kendall's τ = -0.24, p = 0.003). A number of angiographically abnormal regions demonstrated preserved cerebrovascular reserve, likely due to the presence of collaterals. Finally, of the concurrently measured relaxation rates, R2' was superior for oxygenation assessment.
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Affiliation(s)
- Wendy W Ni
- 1 Department of Radiology, Stanford University, Stanford, CA, USA.,2 Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Thomas Christen
- 1 Department of Radiology, Stanford University, Stanford, CA, USA
| | | | - Zungho Zun
- 3 Division of Diagnostic Imaging and Radiology, Children's National Medical Center, Washington, DC, USA.,4 Department of Pediatrics, George Washington University, Washington, DC, USA
| | | | - Greg Zaharchuk
- 1 Department of Radiology, Stanford University, Stanford, CA, USA
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13
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Ni WW, Christen T, Zaharchuk G. Benchmarking transverse spin relaxation based oxygenation measurements in the brain during hypercapnia and hypoxia. J Magn Reson Imaging 2017; 46:704-714. [PMID: 28306210 DOI: 10.1002/jmri.25582] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 09/03/2016] [Accepted: 11/17/2016] [Indexed: 12/19/2022] Open
Abstract
PURPOSE To simultaneously assess reproducibility of three MRI transverse relaxation parameters ( R2', R2*, and R2 ) for brain tissue oxygenation mapping and to assess changes in these parameters with inhalation of gases that increase and decrease oxygenation, to identify the most sensitive parameter for imaging brain oxygenation. MATERIALS AND METHODS Forty-eight healthy subjects (25 male, ages 35 ± 8 years) were scanned at 3.0 Tesla, each with one of four gases (mildly and strongly hypercapnic and hypoxic) administered in a challenge paradigm, using a gas delivery setup designed for patient use. Cerebral blood flow mapping with arterial spin labeling, and simultaneous R2', R2*, and R2 mapping with gradient-echo sampling of free induction decay and echo (GESFIDE) were performed. Reproducibility in air and gas-induced changes were evaluated using nonparametric analysis with correction for multiple comparisons. RESULTS Our gas delivery setup achieved stable gas challenges as shown by physiological monitoring. Test-retest variability of R2', R2*, and R2 were found to be 0.24 s-1 (8.6% of mean), 0.24 s-1 (1.3% of mean), and 0.15 s-1 (1.0% of mean), respectively. Strong hypoxia produced the most conclusive oxygenation-driven relaxation change, inducing increases in R2' (25 ± 13%, P = 0.03), R2* (5 ± 2%, P = 0.02), and R2 (2 ± 2%, NS). CONCLUSION We benchmarked the intra-scan test-retest variability in GESFIDE-based transverse relaxation rate mapping. Using a reliable framework for gas challenge paradigms, we recommend strong hypoxia for validating oxygenation mapping methods, and the use of tissue R2' change, instead of R2* or R2 , as a metric for studying brain tissue oxygenation using transverse relaxation methods. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:704-714.
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Affiliation(s)
- Wendy W Ni
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Thomas Christen
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Greg Zaharchuk
- Department of Radiology, Stanford University, Stanford, California, USA
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14
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Portnoy S, Seed M, Sled JG, Macgowan CK. Non-invasive evaluation of blood oxygen saturation and hematocrit from T 1 and T 2 relaxation times: In-vitro validation in fetal blood. Magn Reson Med 2017; 78:2352-2359. [PMID: 28191646 DOI: 10.1002/mrm.26599] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [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: 07/21/2016] [Revised: 11/17/2016] [Accepted: 12/13/2016] [Indexed: 01/24/2023]
Abstract
PURPOSE We propose an analytical method for calculating blood hematocrit (Hct) and oxygen saturation (sO2 ) from measurements of its T1 and T2 relaxation times. THEORY Through algebraic substitution, established two-compartment relationships describing R1=T1-1 and R2=T2-1 as a function of hematocrit and oxygen saturation were rearranged to solve for Hct and sO2 in terms of R1 and R2 . Resulting solutions for Hct and sO2 are the roots of cubic polynomials. METHODS Feasibility of the method was established by comparison of Hct and sO2 estimates obtained from relaxometry measurements (at 1.5 Tesla) in cord blood specimens to ground-truth values obtained by blood gas analysis. Monte Carlo simulations were also conducted to assess the effect of T1 , T2 measurement uncertainty on precision of Hct and sO2 estimates. RESULTS Good agreement was observed between estimated and ground-truth blood properties (bias = 0.01; 95% limits of agreement = ±0.13 for Hct and sO2 ). Considering the combined effects of biological variability and random measurement noise, we estimate a typical uncertainty of ±0.1 for Hct, sO2 estimates. CONCLUSION Results demonstrate accurate quantification of Hct and sO2 from T1 and T2 . This method is applicable to noninvasive fetal vessel oximetry-an application where existing oximetry devices are unusable or require risky blood-sampling procedures. Magn Reson Med 78:2352-2359, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Sharon Portnoy
- University of Toronto, Department of Medical Biophysics, Toronto, Canada.,Mouse Imaging Centre, Hospital for Sick Children, Toronto, Canada
| | - Mike Seed
- Hospital for Sick Children, Division of Cardiology, Toronto, Canada.,University of Toronto, Department of Pediatrics and Diagnostic Imaging, Toronto, Canada
| | - John G Sled
- University of Toronto, Department of Medical Biophysics, Toronto, Canada.,Mouse Imaging Centre, Hospital for Sick Children, Toronto, Canada.,University of Toronto, Department of Obstetrics and Gynecology, Toronto, Canada
| | - Christopher K Macgowan
- University of Toronto, Department of Medical Biophysics, Toronto, Canada.,Hospital for Sick Children, Department of Physiology and Experimental Medicine, Toronto, Canada
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15
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Dalvit C, Piotto M. 19 F NMR transverse and longitudinal relaxation filter experiments for screening: a theoretical and experimental analysis. Magn Reson Chem 2017; 55:106-114. [PMID: 27514284 DOI: 10.1002/mrc.4500] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 08/09/2016] [Indexed: 06/06/2023]
Abstract
Ligand-based 19 F NMR screening represents an efficient approach for performing binding assays. The high sensitivity of the methodology to receptor binding allows the detection of weak affinity ligands. The observable NMR parameters that are typically used are the 19 F transverse relaxation rate and isotropic chemical shift. However, there are few cases where the 19 F longitudinal relaxation rate should also be used. A theoretical and experimental analysis of the 19 F NMR transverse and longitudinal relaxation rates at different magnetic fields is presented along with proposed methods for improving the sensitivity and dynamic range of these experiments applied to fragment-based screening. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Claudio Dalvit
- Faculty of Science, University of Neuchatel, Neuchatel, Switzerland
- IDD/SDI, Sanofi, Vitry-sur-Seine, France
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16
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Jeun M, Park S, Lee H, Lee KH. Highly sensitive detection of protein biomarkers via nuclear magnetic resonance biosensor with magnetically engineered nanoferrite particles. Int J Nanomedicine 2016; 11:5497-5503. [PMID: 27799772 PMCID: PMC5085298 DOI: 10.2147/ijn.s118156] [Citation(s) in RCA: 6] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Magnetic-based biosensors are attractive for on-site detection of biomarkers due to the low magnetic susceptibility of biological samples. Here, we report a highly sensitive magnetic-based biosensing system that is composed of a miniaturized nuclear magnetic resonance (NMR) device and magnetically engineered nanoferrite particles (NFPs). The sensing performance, also identified as the transverse relaxation (R2) rate, of the NMR device is directly related to the magnetic properties of the NFPs. Therefore, we developed magnetically engineered NFPs (MnMg-NFP) and used them as NMR agents to exhibit a significantly improved R2 rate. The magnetization of the MnMg-NFPs was increased by controlling the Mn and Mg cation concentration and distribution during the synthesis process. This modification of the Mn and Mg cation directly contributed to improving the R2 rate. The miniaturized NMR system, combined with the magnetically engineered MnMg-NFPs, successfully detected a small amount of infectious influenza A H1N1 nucleoprotein with high sensitivity and stability.
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Affiliation(s)
- Minhong Jeun
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science and Technology, Seoul
| | - Sungwook Park
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science and Technology, Seoul; Department of Biomedical Engineering, Korea University of Science and Technology, Daejeon, Republic of Korea
| | - Hakho Lee
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Kwan Hyi Lee
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science and Technology, Seoul; Department of Biomedical Engineering, Korea University of Science and Technology, Daejeon, Republic of Korea
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17
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Fisher ME, Dobberthien BJ, Tessier AG, Yahya A. Characterization of the response of taurine protons to PRESS at 9.4 T for Resolving choline and Determining taurine T2. NMR Biomed 2016; 29:1427-1435. [PMID: 27496562 DOI: 10.1002/nbm.3588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 03/29/2016] [Revised: 06/13/2016] [Accepted: 06/24/2016] [Indexed: 06/06/2023]
Abstract
Point-resolved spectroscopy (PRESS), characterized by two TEs (TE1 and TE2 ), can be employed to perform animal magnetic resonance spectroscopy (MRS) studies at 9.4 T. Taurine (Tau) and choline (Cho) are relevant metabolites that can be measured by MRS. In this work, the response of the J-coupled protons of Tau as a function of PRESS TE1 and TE2 was characterized at 9.4 T to achieve two objectives. The first was to determine two TE1 and TE2 combinations that could be used to obtain T2 -corrected measures of Tau (3.42 ppm) that were minimally influenced by J coupling. The second was to exploit the Tau J coupling to find a timing combination that minimized the 3.25-ppm Tau signal to enable the Cho (3.22 ppm) resonance to be resolved from the overlapping Tau signal. The response of Tau protons was investigated both numerically and experimentally. It was numerically determined that the timings {TE1 , TE2 } = {17 ms, 10 ms} and {TE1 , TE2 } = {80 ms, 70 ms} yielded similar 3.42-ppm Tau resonance areas (5% difference), rendering them suitable for Tau T2 determination. {TE1 , TE2 } = {25 ms, 50 ms} was found to yield minimal 3.25-ppm Tau signal, reducing its interference with Cho. The efficacy of the timings was demonstrated on phantom solutions and in vivo in four Sprague Dawley rats. LCModel was employed to analyse the in vivo spectra and Tau T2 values were estimated by fitting the Tau peak areas obtained with {TE1 , TE2 } = {17 ms, 10 ms} and {TE1 , TE2 } = {80 ms, 70 ms} to a monoexponentially decaying function. An average Tau T2 of 106 ms (standard deviation, 12 ms) was obtained. LCModel analysis of rat spectra obtained with {TE1 , TE2 } = {25 ms, 50 ms} demonstrated negligible levels of Tau signal, compared with that obtained with short TE.
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Affiliation(s)
- Marissa E Fisher
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
| | | | - Anthony G Tessier
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada
| | - Atiyah Yahya
- Department of Oncology, University of Alberta, Edmonton, AB, Canada.
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada.
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18
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Ciris PA, Balasubramanian M, Seethamraju RT, Tokuda J, Scalera J, Penzkofer T, Fennessy FM, Tempany-Afdhal CM, Tuncali K, Mulkern RV. Characterization of gradient echo signal decays in healthy and cancerous prostate at 3T improves with a Gaussian augmentation of the mono-exponential (GAME) model. NMR Biomed 2016; 29:999-1009. [PMID: 27241215 PMCID: PMC4957529 DOI: 10.1002/nbm.3556] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 05/20/2015] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 05/06/2023]
Abstract
A biomarker of cancer aggressiveness, such as hypoxia, could substantially impact treatment decisions in the prostate, especially radiation therapy, by balancing treatment morbidity (urinary incontinence, erectile dysfunction, etc.) against mortality. R2 (*) mapping with Mono-Exponential (ME) decay modeling has shown potential for identifying areas of prostate cancer hypoxia at 1.5T. However, Gaussian deviations from ME decay have been observed in other tissues at 3T. The purpose of this study is to assess whether gradient-echo signal decays are better characterized by a standard ME decay model, or a Gaussian Augmentation of the Mono-Exponential (GAME) decay model, in the prostate at 3T. Multi-gradient-echo signals were acquired on 20 consecutive patients with a clinical suspicion of prostate cancer undergoing MR-guided prostate biopsies. Data were fitted with both ME and GAME models. The information contents of these models were compared using Akaike's information criterion (second order, AICC ), in skeletal muscle, the prostate central gland (CG), and peripheral zone (PZ) regions of interest (ROIs). The GAME model had higher information content in 30% of the prostate on average (across all patients and ROIs), covering up to 67% of cancerous PZ ROIs, and up to 100% of cancerous CG ROIs (in individual patients). The higher information content of GAME became more prominent in regions that would be assumed hypoxic using ME alone, reaching 50% of the PZ and 70% of the CG as ME R2 (*) approached 40 s(-1) . R2 (*) mapping may have important applications in MRI; however, information lost due to modeling could mask differences in parameters due to underlying tissue anatomy or physiology. The GAME model improves characterization of signal behavior in the prostate at 3T, and may increase the potential for determining correlates of fit parameters with biomarkers, for example of oxygenation status.
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Affiliation(s)
- Pelin Aksit Ciris
- Department of Biomedical Engineering, Akdeniz University, Antalya, Turkey
- Harvard Medical School, Boston, MA, USA
- Brigham and Women's Hospital, Boston, MA, USA
| | | | | | - Junichi Tokuda
- Harvard Medical School, Boston, MA, USA
- Brigham and Women's Hospital, Boston, MA, USA
| | - Jonathan Scalera
- Harvard Medical School, Boston, MA, USA
- Brigham and Women's Hospital, Boston, MA, USA
| | - Tobias Penzkofer
- Harvard Medical School, Boston, MA, USA
- Brigham and Women's Hospital, Boston, MA, USA
- Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Fiona M Fennessy
- Harvard Medical School, Boston, MA, USA
- Brigham and Women's Hospital, Boston, MA, USA
- Dana-Farber Cancer Institute, MA, USA
| | | | - Kemal Tuncali
- Harvard Medical School, Boston, MA, USA
- Brigham and Women's Hospital, Boston, MA, USA
| | - Robert V Mulkern
- Harvard Medical School, Boston, MA, USA
- Boston Children's Hospital, Boston, MA, USA
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19
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Balasubramanian M, Jarrett DY, Mulkern RV. Bone marrow segmentation based on a combined consideration of transverse relaxation processes and Dixon oscillations. NMR Biomed 2016; 29:553-562. [PMID: 26866627 DOI: 10.1002/nbm.3498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 08/26/2015] [Revised: 12/04/2015] [Accepted: 01/08/2016] [Indexed: 06/05/2023]
Abstract
The aim of this study was to demonstrate that gradient-echo sampling of single spin echoes can be used to isolate the signal from trabecular bone marrow, with high-quality segmentation and surface reconstructions resulting from the application of simple post-processing strategies. Theoretical expressions of the time-domain single-spin-echo signal were used to simulate signals from bone marrow, non-bone fatty deposits and muscle. These simulations were compared with and used to interpret signals obtained by the application of the gradient-echo sampling of a spin-echo sequence to image the knee and surrounding tissues at 1.5 T. Trabecular bone marrow has a much higher reversible transverse relaxation rate than surrounding non-bone fatty deposits and other musculoskeletal tissues. This observation, combined with a choice of gradient-echo spacing that accentuates Dixon-type oscillations from chemical-shift interference effects, enabled the isolation of bone marrow signal from surrounding tissues through the use of simple image subtraction and thresholding. Three-dimensional renderings of the marrow surface were then readily generated with this approach - renderings that may prove useful for bone morphology assessment, e.g. for the measurement of femoral anteversion. In conclusion, understanding the behavior of signals from bone marrow and surrounding tissue as a function of time through a spin echo facilitates the segmentation and reconstruction of bone marrow surfaces using straightforward post-processing strategies that are typically available on modern radiology workstations.
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Affiliation(s)
- Mukund Balasubramanian
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Delma Y Jarrett
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Robert V Mulkern
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
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20
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Yuan Y, Ding Z, Qian J, Zhang J, Xu J, Dong X, Han T, Ge S, Luo Y, Wang Y, Zhong K, Liang G. Casp3/7-Instructed Intracellular Aggregation of Fe3O4 Nanoparticles Enhances T2 MR Imaging of Tumor Apoptosis. Nano Lett 2016; 16:2686-2691. [PMID: 27031226 DOI: 10.1021/acs.nanolett.6b00331] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Large magnetic nanoparticles or aggregates are advantageous in their magnetic resonance properties over ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles (NPs), but the former are cleared faster from the blood pool. Therefore, the "smart" strategy of intracellular aggregation of USPIO NPs is required for enhanced T2-weighted MR imaging. Herein, employing an enzyme-instructed condensation reaction, we rationally designed a small molecule Ac-Asp-Glu-Val-Asp-Cys(StBu)-Lys-CBT (1) to covalently modify USPIO NPs to prepare monodispersive Fe3O4@1 NPs. In vitro results showed that Fe3O4@1 NPs could be subjected to caspase 3 (Casp3)-instructed aggregation. T2 phantom MR imaging showed that the transverse molar relaxivity (r2) of Fe3O4@1 NPs with Casp3 or apoptotic HepG2 cells was significantly larger than those of control groups. In vivo tumor MR imaging results indicated that Fe3O4@1 NPs could be specifically applied for enhanced T2 MR imaging of tumor apoptosis. We propose that the enzyme-instructed intracellular aggregation of Fe3O4 NPs could be a novel strategy for the design of "smart" probes for efficient T2 MR imaging of in vivo biomarkers.
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Affiliation(s)
- Yue Yuan
- CAS Key Laboratory of Soft Matter Chemistry, Department of Chemistry, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Zhanling Ding
- CAS Key Laboratory of Soft Matter Chemistry, Department of Chemistry, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Junchao Qian
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences , 350 Shushanhu Road, Hefei, Anhui 230031, China
| | - Jia Zhang
- CAS Key Laboratory of Soft Matter Chemistry, Department of Chemistry, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Jinyong Xu
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences , 350 Shushanhu Road, Hefei, Anhui 230031, China
| | - Xuejiao Dong
- CAS Key Laboratory of Soft Matter Chemistry, Department of Chemistry, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Tao Han
- CAS Key Laboratory of Soft Matter Chemistry, Department of Chemistry, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Shuchao Ge
- School of Life Sciences, University of Science and Technology of China , Hefei, Anhui 230027, China
| | - Yufeng Luo
- CAS Key Laboratory of Soft Matter Chemistry, Department of Chemistry, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Yuwei Wang
- CAS Key Laboratory of Soft Matter Chemistry, Department of Chemistry, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Kai Zhong
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences , 350 Shushanhu Road, Hefei, Anhui 230031, China
| | - Gaolin Liang
- CAS Key Laboratory of Soft Matter Chemistry, Department of Chemistry, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China
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21
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Ciris PA, Balasubramanian M, Damato AL, Seethamraju RT, Tempany-Afdhal CM, Mulkern RV, Viswanathan AN. Characterizing gradient echo signal decays in gynecologic cancers at 3T using a Gaussian augmentation of the monoexponential (GAME) model. J Magn Reson Imaging 2016; 44:1020-30. [PMID: 26971387 DOI: 10.1002/jmri.25226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 07/02/2015] [Accepted: 02/23/2016] [Indexed: 12/26/2022] Open
Abstract
PURPOSE To assess whether R2* mapping with a standard Monoexponential (ME) or a Gaussian Augmentation of the Monoexponential (GAME) decay model better characterizes gradient-echo signal decays in gynecological cancers after external beam radiation therapy at 3T, and evaluate implications of modeling for noninvasive identification of intratumoral hypoxia. MATERIALS AND METHODS Multi-gradient-echo signals were acquired on 25 consecutive patients with gynecologic cancers and three healthy participants during inhalation of different oxygen concentrations at 3T. Data were fitted with both ME and GAME models. Models were compared using F-tests in tumors and muscles in patients, muscles, cervix, and uterus in healthy participants, and across oxygenation levels. RESULTS GAME significantly improved fitting over ME (P < 0.05): Improvements with GAME covered 34% of tumor regions-of-interest on average, ranging from 6% (of a vaginal tumor) to 68% (of a cervical tumor) in individual tumors. Improvements with GAME were more prominent in areas that would be assumed hypoxic based on ME alone, reaching 90% as ME R2* approached 100 Hz. Gradient echo decay parameters at different oxygenation levels were not significantly different (P = 0.81). CONCLUSION R2* may prove sensitive to hypoxia; however, inaccurate representations of underlying data may limit the success of quantitative assessments. Although the degree to which R2 or σ values correlate with hypoxia remains unknown, improved characterization with GAME increases the potential for determining any correlates of fit parameters with biomarkers, such as oxygenation status. J. MAGN. RESON. IMAGING 2016;44:1020-1030.
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Affiliation(s)
- Pelin A Ciris
- Biomedical Engineering, Akdeniz University, Antalya, Turkey. .,Harvard Medical School, Boston, Massachusetts, USA. .,Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA.
| | - Mukund Balasubramanian
- Harvard Medical School, Boston, Massachusetts, USA.,Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Antonio L Damato
- Harvard Medical School, Boston, Massachusetts, USA.,Radiation Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | | | - Clare M Tempany-Afdhal
- Harvard Medical School, Boston, Massachusetts, USA.,Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Robert V Mulkern
- Harvard Medical School, Boston, Massachusetts, USA.,Radiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Akila N Viswanathan
- Harvard Medical School, Boston, Massachusetts, USA.,Siemens Healthcare, Boston, Massachusetts, USA
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22
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Breitkreutz DY, Fallone BG, Yahya A. Effect of J coupling on 1.3-ppm lipid methylene signal acquired with localised proton MRS at 3 T. NMR Biomed 2015; 28:1324-1331. [PMID: 26314546 DOI: 10.1002/nbm.3387] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [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: 05/05/2015] [Revised: 07/10/2015] [Accepted: 07/30/2015] [Indexed: 06/04/2023]
Abstract
The purpose of this work was to investigate the effect of J-coupling interactions on the quantification and T2 determination of 1.3-ppm lipid methylene protons at 3 T. The response of the 1.3-ppm protons of hexanoic, heptanoic, octanoic, linoleic and oleic acid was measured as a function of point-resolved spectroscopy (PRESS) and stimulated echo acquisition mode (STEAM) TE. In addition, a narrow-bandwidth refocusing PRESS sequence designed to rewind J-coupling evolution of the 1.3-ppm protons was applied to the five fatty acids, to corn oil and to tibial bone marrow of six healthy volunteers. Peak areas were plotted as a function of TE, and data were fitted to monoexponentially decaying functions to determine Mo (the extrapolated area for TE = 0 ms) and T2 values. In phantoms, rewinding J-coupling evolution resulted in 198%, 64%, 44%, 20% and 15% higher T2 values for heptanoic, octanoic, linoleic and oleic acid, and corn oil, respectively, compared with those obtained with standard PRESS. The narrow-bandwidth PRESS sequence also resulted in significant changes in Mo , namely -77%, -22%, 28%, 23% and 28% for heptanoic, octanoic, linoleic and oleic acid, and corn oil, respectively. T2 values obtained with STEAM were closer to the values measured with narrow-bandwidth PRESS. On average, in tibial bone marrow (six volunteers) rewinding J-coupling evolution resulted in 21% ± 3% and 9 % ± 1% higher Mo and T2 values, respectively. This work demonstrates that the consequence of neglecting to consider scalar coupling effects on the quantification of 1.3-ppm lipid methylene protons and their T2 values is not negligible. The linoleic and oleic acid T2 results indicate that T2 measures of lipids with standard MRS techniques are dependent on lipid composition.
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Affiliation(s)
| | - B Gino Fallone
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada
| | - Atiyah Yahya
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada
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Towse TF, Childs BT, Sabin SA, Bush EC, Elder CP, Damon BM. Comparison of muscle BOLD responses to arterial occlusion at 3 and 7 Tesla. Magn Reson Med 2015; 75:1333-40. [PMID: 25884888 DOI: 10.1002/mrm.25562] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [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: 09/03/2014] [Revised: 10/21/2014] [Accepted: 11/12/2014] [Indexed: 12/16/2022]
Abstract
PURPOSE The purpose of this study was to determine the feasibility of muscle BOLD (mBOLD) imaging at 7 Tesla (T) by comparing the changes in R2* of muscle at 3 and 7T in response to a brief period of tourniquet-induced ischemia. METHODS Eight subjects (three male), aged 29.5 ± 6.1 years (mean ± standard deviation, SD), 167.0 ± 10.6 cm tall with a body mass of 62.0 ± 18.0 kg, participated in the study. Subjects reported to the lab on four separate occasions including a habituation session, two MRI scans, and in a subset of subjects, a session during which changes in blood flow and blood oxygenation were quantified using Doppler ultrasound (U/S) and near-infrared spectroscopy (NIRS) respectively. For statistical comparisons between 3 and 7T, R2* rate constants were calculated as R2* = 1/T2*. RESULTS The mean preocclusion R2* value was greater at 7T than at 3T (60.16 ± 2.95 vs. 35.17 ± 0.35 s(-1), respectively, P < 0.001). Also, the mean ΔR2 *END and ΔR2*POST values were greater for 7T than for 3T (-2.36 ± 0.25 vs. -1.24 ± 0.39 s(-1), respectively, Table 1). CONCLUSION Muscle BOLD contrast at 7T is as much as six-fold greater than at 3T. In addition to providing greater SNR and CNR, 7T mBOLD studies may offer further advantages in the form of greater sensitivity to pathological changes in the muscle microcirculation.
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Affiliation(s)
- Theodore F Towse
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Physical Medicine and Rehabilitation, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Benjamin T Childs
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Shea A Sabin
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Emily C Bush
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Christopher P Elder
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Bruce M Damon
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
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24
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Craveiro M, Cudalbu C, Mlynárik V, Gruetter R. Optimized MEGA-SPECIAL for in vivo glutamine detection in the rat brain at 14.1 T. NMR Biomed 2014; 27:1151-1158. [PMID: 25070114 DOI: 10.1002/nbm.3168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 11/11/2013] [Revised: 04/04/2014] [Accepted: 06/22/2014] [Indexed: 06/03/2023]
Abstract
Glutamine has multiple roles in brain metabolism and its concentration can be altered in various pathological conditions. An accurate knowledge of its concentration is therefore highly desirable to monitor and study several brain disorders in vivo. However, in recent years, several MRS studies have reported conflicting glutamine concentrations in the human brain. A recent hypothesis for explaining these discrepancies is that a short T2 component of the glutamine signal may impact on its quantification at long echo times. The present study therefore aimed to investigate the impact of acquisition parameters on the quantified glutamine concentration using two different acquisition techniques, SPECIAL at ultra-short echo time and MEGA-SPECIAL at moderate echo time. For this purpose, MEGA-SPECIAL was optimized for the first time for glutamine detection. Based on the very good agreement of the glutamine concentration obtained between the two measurements, it was concluded that no impact of a short T2 component of the glutamine signal was detected.
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Affiliation(s)
- Mélanie Craveiro
- Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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25
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Bouhrara M, Reiter DA, Spencer RG. Bayesian analysis of transverse signal decay with application to human brain. Magn Reson Med 2014; 74:785-802. [PMID: 25242062 DOI: 10.1002/mrm.25457] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [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: 05/08/2014] [Revised: 08/23/2014] [Accepted: 08/24/2014] [Indexed: 12/20/2022]
Abstract
PURPOSE Transverse relaxation analysis with several signal models has been used extensively to determine tissue and material properties. However, the derivation of corresponding parameter values is notoriously unreliable. We evaluate improvements in the quality of parameter estimation using Bayesian analysis and incorporating the Rician noise model, as appropriate for magnitude MR images. THEORY AND METHODS Monoexponential, stretched exponential, and biexponential signal models were analyzed using nonlinear least squares (NLLS) and Bayesian approaches. Simulations and phantom and human brain data were analyzed using three different approaches to account for noise. Parameter estimation bias (reflecting accuracy) and dispersion (reflecting precision) were derived for a range of signal-to-noise ratios (SNR) and relaxation parameters. RESULTS All methods performed well at high SNR. At lower SNR, the Bayesian approach yielded parameter estimates of considerably greater precision, as well as greater accuracy, than did NLLS. Incorporation of the Rician noise model greatly improved accuracy and, to a somewhat lesser extent, precision, in derived transverse relaxation parameters. Analyses of data obtained from solution phantoms and from brain were consistent with simulations. CONCLUSION Overall, estimation of parameters characterizing several different transverse relaxation models was markedly improved through use of Bayesian analysis and through incorporation of the Rician noise model.
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Affiliation(s)
- Mustapha Bouhrara
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - David A Reiter
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Richard G Spencer
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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26
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Semmineh NB, Xu J, Skinner JT, Xie J, Li H, Ayers G, Quarles CC. Assessing tumor cytoarchitecture using multiecho DSC-MRI derived measures of the transverse relaxivity at tracer equilibrium (TRATE). Magn Reson Med 2014; 74:772-84. [PMID: 25227668 DOI: 10.1002/mrm.25435] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [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: 01/13/2014] [Revised: 08/06/2014] [Accepted: 08/10/2014] [Indexed: 01/06/2023]
Abstract
PURPOSE In brain tumor dynamic susceptibility contrast (DSC)-MRI studies, multiecho acquisition methods are used to quantify the dynamic changes in T1 and T2 * that occur when contrast agent (CA) extravasates. Such methods also enable the estimation of the effective tissue CA transverse relaxivity. The goal of this study was to evaluate the sensitivity of the transverse relaxivity at tracer equilibrium (TRATE) to tumor cytoarchitecture. METHODS Computational and in vitro studies were used to evaluate the biophysical basis of TRATE. In 9L, C6, and human brain tumors, TRATE, the apparent diffusion coefficient (ADC), the CA transfer constant (K(trans) ), the extravascular extracellular volume fraction (ve ), and histological data were compared. RESULTS Simulations and in vitro results indicate that TRATE is highly sensitive to variations in cellular properties such as cell size and density. The histologic cell density and TRATE values were significantly higher in 9L tumors as compared to C6 tumors. In animal and human tumors, a voxel-wise comparison of TRATE with ADC, ve , and K(trans) maps showed low spatial correlation. CONCLUSION The assessment of TRATE is clinically feasible and its sensitivity to tissue cytoarchitectural features not present in other imaging methods indicate that it could potentially serve as a unique structural signature or "trait" of cancer.
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Affiliation(s)
- Natenael B Semmineh
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA
| | - Junzhong Xu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Jack T Skinner
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Jingping Xie
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Hua Li
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA
| | - Gregory Ayers
- Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, USA
| | - C Chad Quarles
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Department of Cancer Biology, Vanderbilt University, Nashville, Tennessee, USA
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Weiskopf N, Callaghan MF, Josephs O, Lutti A, Mohammadi S. Estimating the apparent transverse relaxation time (R2(*)) from images with different contrasts (ESTATICS) reduces motion artifacts. Front Neurosci 2014; 8:278. [PMID: 25309307 PMCID: PMC4159978 DOI: 10.3389/fnins.2014.00278] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [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: 04/11/2014] [Accepted: 08/18/2014] [Indexed: 12/26/2022] Open
Abstract
Relaxation rates provide important information about tissue microstructure. Multi-parameter mapping (MPM) estimates multiple relaxation parameters from multi-echo FLASH acquisitions with different basic contrasts, i.e., proton density (PD), T1 or magnetization transfer (MT) weighting. Motion can particularly affect maps of the apparent transverse relaxation rate R2*, which are derived from the signal of PD-weighted images acquired at different echo times. To address the motion artifacts, we introduce ESTATICS, which robustly estimates R2* from images even when acquired with different basic contrasts. ESTATICS extends the fitted signal model to account for inherent contrast differences in the PDw, T1w and MTw images. The fit was implemented as a conventional ordinary least squares optimization and as a robust fit with a small or large confidence interval. These three different implementations of ESTATICS were tested on data affected by severe motion artifacts and data with no prominent motion artifacts as determined by visual assessment or fast optical motion tracking. ESTATICS improved the quality of the R2* maps and reduced the coefficient of variation for both types of data—with average reductions of 30% when severe motion artifacts were present. ESTATICS can be applied to any protocol comprised of multiple 2D/3D multi-echo FLASH acquisitions as used in the general research and clinical setting.
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Affiliation(s)
- Nikolaus Weiskopf
- Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London London, UK
| | - Martina F Callaghan
- Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London London, UK
| | - Oliver Josephs
- Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London London, UK ; Birkbeck-UCL Centre for NeuroImaging London, UK
| | - Antoine Lutti
- Laboratoire de Recherche en Neuroimagerie, Department of Clinical Neurosciences, Centre Hospitalier Universitaire Vaudois Lausanne, Switzerland
| | - Siawoosh Mohammadi
- Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London London, UK
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Mulkern RV, Balasubramanian M, Mitsouras D. On the lorentzian versus Gaussian character of time-domain spin-echo signals from the brain as sampled by means of gradient-echoes: Implications for quantitative transverse relaxation studies. Magn Reson Med 2014; 74:51-62. [PMID: 25078089 DOI: 10.1002/mrm.25365] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [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: 01/30/2014] [Revised: 06/19/2014] [Accepted: 06/24/2014] [Indexed: 11/09/2022]
Abstract
PURPOSE To determine whether Lorentzian or Gaussian intra-voxel frequency distributions are better suited for modeling data acquired with gradient-echo sampling of single spin-echoes for the simultaneous characterization of irreversible and reversible relaxation rates. Clinical studies (e.g., of brain iron deposition) using such acquisition schemes have typically assumed Lorentzian distributions. THEORY AND METHODS Theoretical expressions of the time-domain spin-echo signal for intra-voxel Lorentzian and Gaussian distributions were used to fit data from a human brain scanned at both 1.5 Tesla (T) and 3T, resulting in maps of irreversible and reversible relaxation rates for each model. The relative merits of the Lorentzian versus Gaussian model were compared by means of quality of fit considerations. RESULTS Lorentzian fits were equivalent to Gaussian fits primarily in regions of the brain where irreversible relaxation dominated. In the multiple brain regions where reversible relaxation effects become prominent, however, Gaussian fits were clearly superior. CONCLUSION The widespread assumption that a Lorentzian distribution is suitable for quantitative transverse relaxation studies of the brain should be reconsidered, particularly at 3T and higher field strengths as reversible relaxation effects become more prominent. Gaussian distributions offer alternate fits of experimental data that should prove quite useful in general. Magn Reson Med 74:51-62, 2015. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Robert V Mulkern
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Mukund Balasubramanian
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Dimitrios Mitsouras
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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29
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Yadav NN, Xu J, Bar-Shir A, Qin Q, Chan KWY, Grgac K, Li W, McMahon MT, van Zijl PCM. Natural D-glucose as a biodegradable MRI relaxation agent. Magn Reson Med 2014; 72:823-8. [PMID: 24975029 DOI: 10.1002/mrm.25329] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [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: 01/28/2014] [Revised: 05/31/2014] [Accepted: 06/02/2014] [Indexed: 11/06/2022]
Abstract
PURPOSE Demonstrate applicability of natural D-glucose as a T2 MRI contrast agent. METHODS D-glucose solutions were prepared at multiple concentrations and variable pH. The relaxation rate (R2 = 1/T2 ) was measured at 3, 7, and 11.7 T. Additional experiments were performed on blood at 11.7 T. Also, a mouse was infused with D-glucose (3.0 mmol/kg) and dynamic T2 weighted images of the abdomen acquired. RESULTS The transverse relaxation rate depended strongly on glucose concentration and solution pH. A maximum change in R2 was observed around physiological pH (pH 6.8-7.8). The transverse relaxivities at 22°C (pH 7.3) were 0.021, 0.060, and 0.077 s(-1) mM(-1) at 3.0, 7.0, and 11.7 T, respectively. These values showed good agreement with expected values from the Swift-Connick equation. There was no significant dependence on glucose concentration or pH for T1 and the diffusion coefficient for these solutions. The transverse relaxivity in blood at 11.7 T was 0.09 s(-1) mM(-1) . The dynamic in vivo experiment showed a 10% drop in signal intensity after glucose infusion followed by recovery of the signal intensity after about 50-100 s. CONCLUSION Glucose can be used as a T2 contrast agent for MRI at concentrations that are already approved for human use.
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Affiliation(s)
- Nirbhay N Yadav
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA
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Ni W, Christen T, Zun Z, Zaharchuk G. Comparison of R2' measurement methods in the normal brain at 3 Tesla. Magn Reson Med 2014; 73:1228-36. [PMID: 24753286 DOI: 10.1002/mrm.25232] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [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: 12/10/2013] [Revised: 03/05/2014] [Accepted: 03/07/2014] [Indexed: 01/12/2023]
Abstract
PURPOSE R2', the reversible component of transverse relaxation, is an important susceptibility measurement for studies of brain physiology and pathologies. In existing literature, different R2' measurement methods are used with assumption of equivalency. This study explores the choice of measurement method in healthy, young subjects at 3T. METHODS In this study, a modified gradient-echo sampling of free induction decay and echo (GESFIDE) sequence was used to compare four standard R2' measurement methods: asymmetric spin echo (ASE), standard GESFIDE, gradient echo sampling of the spin echo (GESSE), and separate R2 and R2* mapping. RESULTS GESSE returned lower R2' measurements than other methods (P < 0.05). Intersubject mean R2' in gray matter was found to be 2.7 s(-1) using standard GESFIDE and GESSE, versus 3.4-3.8 s(-1) using other methods. In white matter, mean R2' from GESSE was 2.3 s(-1) while other methods produced 3.7-4.3 s(-1) . R2 correction was applied to partially reduce the discrepancies between the methods, but significant differences remained, likely due to violation of the fundamental assumption of a single-compartmental tissue model, and hence monoexponential decay. CONCLUSION R2' measurements are influenced significantly by the choice of method. Awareness of this issue is important when designing and interpreting studies that involve R2' measurements.
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Affiliation(s)
- Wendy Ni
- Department of Radiology, Stanford University, Stanford, California, USA; Department of Electrical Engineering, Stanford University, Stanford, California, USA
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Callaghan MF, Helms G, Lutti A, Mohammadi S, Weiskopf N. A general linear relaxometry model of R1 using imaging data. Magn Reson Med 2014; 73:1309-14. [PMID: 24700606 PMCID: PMC4359013 DOI: 10.1002/mrm.25210] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/21/2014] [Accepted: 02/23/2014] [Indexed: 12/20/2022]
Abstract
PURPOSE The longitudinal relaxation rate (R1 ) measured in vivo depends on the local microstructural properties of the tissue, such as macromolecular, iron, and water content. Here, we use whole brain multiparametric in vivo data and a general linear relaxometry model to describe the dependence of R1 on these components. We explore a) the validity of having a single fixed set of model coefficients for the whole brain and b) the stability of the model coefficients in a large cohort. METHODS Maps of magnetization transfer (MT) and effective transverse relaxation rate (R2 *) were used as surrogates for macromolecular and iron content, respectively. Spatial variations in these parameters reflected variations in underlying tissue microstructure. A linear model was applied to the whole brain, including gray/white matter and deep brain structures, to determine the global model coefficients. Synthetic R1 values were then calculated using these coefficients and compared with the measured R1 maps. RESULTS The model's validity was demonstrated by correspondence between the synthetic and measured R1 values and by high stability of the model coefficients across a large cohort. CONCLUSION A single set of global coefficients can be used to relate R1 , MT, and R2 * across the whole brain. Our population study demonstrates the robustness and stability of the model.
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Affiliation(s)
- Martina F Callaghan
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College LondonLondon, United Kingdom
- * Correspondence to: Martina F. Callaghan, Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK. E-mail:
| | - Gunther Helms
- MR Research in Neurology and Psychiatry, Department of Cognitive Neurology, University Medical CenterGoettingen, Germany
| | - Antoine Lutti
- LREN, Department des Neurosciences Cliniques, CHUV, Universite de LausanneLausanne, Switzerland
| | - Siawoosh Mohammadi
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College LondonLondon, United Kingdom
| | - Nikolaus Weiskopf
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College LondonLondon, United Kingdom
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Gregori J, Schuff N, Kern R, Günther M. T2-based arterial spin labeling measurements of blood to tissue water transfer in human brain. J Magn Reson Imaging 2013; 37:332-42. [PMID: 23019041 PMCID: PMC3554863 DOI: 10.1002/jmri.23822] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 08/14/2012] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To investigate blood to tissue water transfer in human brain, in vivo and spatially resolved using a T2-based arterial spin labeling (ASL) method with 3D readout. MATERIALS AND METHODS A T2-ASL method is introduced to measure the water transfer processes between arterial blood and brain tissue based on a 3D-GRASE (gradient and spin echo) pulsed ASL sequence with multiecho readout. An analytical mathematical model is derived based on the General Kinetic Model, including blood and tissue compartment, T1 and T2 relaxation, and a blood-to-tissue transfer term. Data were collected from healthy volunteers on a 3 T system. The mean transfer time parameter T(bl → ex) (blood to extravascular compartment transfer time) was derived voxelwise by nonlinear least-squares fitting. RESULTS Whole-brain maps of T(bl → ex) show stable results in cortical regions, yielding different values depending on the brain region. The mean value across subjects and regions of interest (ROIs) in gray matter was 440 ± 30 msec. CONCLUSION A novel method to derive whole-brain maps of blood to tissue water transfer dynamics is demonstrated. It is promising for the investigation of underlying physiological mechanisms and development of diagnostic applications in cerebrovascular diseases.
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Affiliation(s)
- Johannes Gregori
- Institute for Medical Image Computing MEVIS, Fraunhofer MEVIS, Bremen, Germany.
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Intrapiromkul J, Zhu H, Cheng Y, Barker PB, Edden RAE. Determining the in vivo transverse relaxation time of GABA in the human brain at 7T. J Magn Reson Imaging 2012; 38:1224-9. [PMID: 23239232 DOI: 10.1002/jmri.23979] [Citation(s) in RCA: 10] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 11/06/2012] [Indexed: 12/25/2022] Open
Abstract
PURPOSE To measure in vivo transverse relaxation times (T2 ) of gamma-aminobutyric acid (GABA) at 7T using the experimental spectral-editing method. MATERIALS AND METHODS Experiments were performed at 7T in a 10 mM GABA phantom to determine the intrinsic TE-dependence of the edited signal. Then the same method was applied with editing-based suppression of coedited macromolecular signals to five healthy volunteers to determine T2 of GABA in vivo. RESULTS From in vivo data acquired at multiple echo times, the in vivo GABA T2 relaxation time was estimated to be 63 ± 19 msec. CONCLUSION We present a measurement of the T2 of edited GABA signal at 7T by first using phantom measurements to determine the echo time-dependence of edited signal. The method is purely experimental and does not rely on prior knowledge of coupling constants or simulation of realistic experiments. J. Magn. Reson. Imaging 2013;38:1224-1229. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Jarunee Intrapiromkul
- Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Mitsumori F, Watanabe H, Takaya N, Garwood M, Auerbach EJ, Michaeli S, Mangia S. Toward understanding transverse relaxation in human brain through its field dependence. Magn Reson Med 2012; 68:947-53. [PMID: 22161735 PMCID: PMC3424402 DOI: 10.1002/mrm.23301] [Citation(s) in RCA: 21] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 10/24/2011] [Accepted: 10/26/2011] [Indexed: 12/23/2022]
Abstract
Apparent transverse-relaxation rate constants (R₂⁺ = 1/T₂⁺) were measured in various regions of the healthy human brain using a multiecho adiabatic spin-echo sequence at five different magnetic fields, 1.5, 1.9, 3, 4.7, and 7 T. The R₂⁺ values showed a clear dependence on magnetic field strength (B(0) ). The regional distribution of the R ₂⁺ was well explained by the sum of three components: (1) regional nonhemin iron concentration ([Fe]), (2) regional macromolecular mass fraction (f(M) ), and (3) a region-independent factor. Accordingly, R₂⁺ = α[Fe] + βf(M) + γ, where coefficients α, β, and γ were experimentally determined at each magnetic field by a least square fitting method using multiple regression analysis. Although the coefficient α linearly increased with B(0) , β showed a quadratic dependence on top of a field-independent component. The coefficient γ also increased slightly with B(0) on top of a field-independent component. The linear dependence of α on B(0) was consistent with that observed for the transverse-relaxation rate of water protons in ferritin solutions as found previously by others. The quadratic dependence of β on B(0) was accounted for by isochronous and anisochronous exchange mechanisms using intrinsic-relaxation parameters obtained from the literature.
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Potapov A, Thurber KR, Yau WM, Tycko R. Dynamic nuclear polarization-enhanced ¹H-¹³C double resonance NMR in static samples below 20 K. J Magn Reson 2012; 221:32-40. [PMID: 22743540 PMCID: PMC3727229 DOI: 10.1016/j.jmr.2012.05.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [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: 03/20/2012] [Revised: 05/07/2012] [Accepted: 05/09/2012] [Indexed: 05/21/2023]
Abstract
We demonstrate the feasibility of one-dimensional and two-dimensional ¹H-¹³C double resonance NMR experiments with dynamic nuclear polarization (DNP) at 9.4 T and temperatures below 20 K, including both ¹H-¹³C cross-polarization and ¹H decoupling, and discuss the effects of polarizing agent type, polarizing agent concentration, temperature, and solvent deuteration. We describe a two-channel low-temperature DNP/NMR probe, capable of carrying the radio-frequency power load required for ¹H-¹³C cross-polarization and high-power proton decoupling. Experiments at 8 K and 16 K reveal a significant T₂ relaxation of ¹³C, induced by electron spin flips. Carr-Purcell experiments and numerical simulations of Carr-Purcell dephasing curves allow us to determine the effective correlation time of electron flips under our experimental conditions. The dependence of the DNP signal enhancement on electron spin concentration shows a maximum near 80 mM. Although no significant difference in the absolute DNP enhancements for triradical (DOTOPA-TEMPO) and biradical (TOTAPOL) dopants was found, the triradical produced greater DNP build-up rates, which are advantageous for DNP experiments. Additionally the feasibility of structural measurements on ¹³C-labeled biomolecules was demonstrated with a two-dimensional ¹³C-¹³C exchange spectrum of selectively ¹³C-labeled β-amyloid fibrils.
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Affiliation(s)
- Alexey Potapov
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Bethesda, MD 20892-0520, USA.
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Reiter DA, Roque RA, Lin PC, Doty SB, Pleshko N, Spencer RG. Improved specificity of cartilage matrix evaluation using multiexponential transverse relaxation analysis applied to pathomimetically degraded cartilage. NMR Biomed 2011; 24:1286-94. [PMID: 21465593 PMCID: PMC3487711 DOI: 10.1002/nbm.1690] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [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: 04/26/2010] [Revised: 01/05/2011] [Accepted: 01/17/2011] [Indexed: 05/11/2023]
Abstract
The noninvasive early detection of specific matrix alterations in degenerative cartilage disease would be of substantial use in basic science studies and clinically, but remains an elusive goal. Recently developed MRI methods exhibit some specificity, but require contrast agents or nonstandard pulse sequences and hardware. We present a multiexponential approach which does not require contrast agents or specialized hardware, and uses a standard multiple-echo spin-echo sequence. Experiments were performed on tissue models of degenerative cartilage using enzymes with distinct actions. MR results were validated using histologic, biochemical and infrared spectroscopic analyses. The sulfated glycosaminoglycan per dry weight (dw) in bovine nasal cartilage was 0.72 ± 0.06 mg/mg dw and was reduced through chondroitinase AC and collagenase digestion to 0.56 ± 0.12 and 0.58 ± 0.13 mg/mg dw, respectively. Multiexponential analysis of data obtained at 9.4 T permitted the identification of tissue compartments assigned to the proteoglycan component of the matrix and to bulk water. Enzymatic treatment resulted in a significant reduction in the ratio of proteoglycan-bound to free water from 0.13 ± 0.02 in control cartilage to 0.03 ± 0.02 and 0.05 ± 0.06 under chondroitinase AC and collagenase treatment, respectively. As expected, monoexponential T(2) increased with both degradation protocols, but without further specificity to the nature of the degradation. An important eventual extension of this approach may be to map articular cartilage degeneration in the clinical setting. As an initial step towards this, localized multiexponential T(2) analysis was performed on control and trypsin treated excised bovine patella. The results obtained on this articular cartilage sample were readily interpretable in terms of proteoglycan-associated and relatively free water compartments. In potential clinical applications, signal-to-noise ratio constraints will define the threshold for the detection of macromolecular compartment changes at a given spatial scale. The multiexponential approach has potential application to the early detection of cartilage degradation with the use of appropriate pulse parameters under high signal-to-noise ratio conditions.
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Affiliation(s)
- David A Reiter
- Magnetic Resonance Imaging and Spectroscopy Section, National Institute of Aging, National Institutes on Health, Baltimore, MD, USA.
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Abstract
When applying RF saturation to tissue, MRI signal reductions occur due to magnetization transfer (MT) and direct saturation (DS) effects on water protons. It is shown that the direct effects, often considered a nuisance, can be used to distinguish gray matter (GM) regions with different iron content. DS effects were selected by reducing the magnitude and duration of RF irradiation to minimize confounding MT effects. Contrary to MT saturation spectra, direct water saturation spectra are characterized by a symmetric Lorentzian-shaped frequency dependence that can be described by an exact analytical solution of the Bloch equations. The effect of increased transverse relaxation, e.g., due to the presence of iron, will broaden this saturation spectrum. As a first application, DS ratio (DSR) images were acquired to visualize GM structures in the human brain. Similar to T(2)*-weighted images, the quality of DSR images was affected by local field inhomogeneity, but this could be easily corrected for by centering the saturation spectrum on a voxel-by-voxel basis. The results show that, contrary to commonly used T(2)*-weighted and absolute R(2) images, the DSR images visualize all GM structures, including cortex. A direct correlation between DSR and iron content was confirmed for these structures.
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Affiliation(s)
- Seth A. Smith
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD
- F.M. Kirby Research Center for Functional Brain Imaging Kennedy Krieger Institute, Baltimore, MD
| | - Jeff W.M. Bulte
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD
- Department of Chemical & Biomolecular Engineering, The Johns Hopkins University Whiting School of Engineering
- Cellular Imaging Section and Vascular Biology Program, Institute for Cellular Engineering, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Peter C. M. van Zijl
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD
- F.M. Kirby Research Center for Functional Brain Imaging Kennedy Krieger Institute, Baltimore, MD
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Smith LM, Maher AD, Want EJ, Elliott P, Stamler J, Hawkes GE, Holmes E, Lindon JC, Nicholson JK. Large-scale human metabolic phenotyping and molecular epidemiological studies via 1H NMR spectroscopy of urine: investigation of borate preservation. Anal Chem 2009; 81:4847-56. [PMID: 19453167 PMCID: PMC2721977 DOI: 10.1021/ac9004875] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [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] [Indexed: 01/11/2023]
Abstract
Borate is an antibacterial preservative widely used in clinical and large-scale epidemiological studies involving urine sample analysis. Since it readily forms covalent adducts and reversible complexes with hydroxyl and carboxylate groups, the effects of borate preservation in (1)H NMR-spectroscopy-based metabolic profiling of human urine samples have been assessed. Effects of various concentrations of borate (range 0-30 mM) on (1)H NMR spectra of urine were observed at sequential time points over a 12 month period. Consistent with known borate chemistry, the principal alterations in the (1)H resonance metabolite patterns were observed for compounds such as mannitol, citrate, and alpha-hydroxyisobutyrate and confirmed by ESI-MS analysis. These included line-broadening, T(1) and T(2) relaxation, and chemical shift changes consistent with complex formation and chemical exchange processes. To further investigate complexation behavior in the urinary metabolite profiles, a new tool for visualization of multicomponent relaxation variations in which the spectra were color-coded according to the T(1) and T(2) proton relaxation times respectively (T(1) or T(2) ordered projection spectroscopy, TOPSY) was also developed and applied. Addition of borate caused a general decrease in (1)H T(1) values, consistent with nonspecific effects such as solution viscosity changes. Minor changes in proton T(2) relaxation rates were observed for the most strongly complexing metabolites. From a molecular phenotyping and epidemiologic viewpoint, typical interpersonal biological variation was shown to be vastly greater than any variation introduced by the borate complexation, which had a negligible effect on the metabolic mapping and classification of samples. While caution is indicated in the assignment of biomarker signals where metabolites have diol groupings or where there are adjacent hydroxyl and carboxylate functions, it is concluded that borate preservation is "fit-for-purpose" for (1)H NMR-based epidemiological studies, since the essential biochemical classification features of the samples are robustly maintained.
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Affiliation(s)
- Leon M. Smith
- Department of Biomolecular Medicine, Faculty of Medicine, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Anthony D. Maher
- Department of Biomolecular Medicine, Faculty of Medicine, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Elizabeth J. Want
- Department of Biomolecular Medicine, Faculty of Medicine, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Paul Elliott
- Department of Epidemiology & Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London, W2 1PG, UK
| | - Jeremiah Stamler
- Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Geoffrey E. Hawkes
- School of Biological and Chemical Sciences, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, UK
| | - Elaine Holmes
- Department of Biomolecular Medicine, Faculty of Medicine, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - John C. Lindon
- Department of Biomolecular Medicine, Faculty of Medicine, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Jeremy K. Nicholson
- Department of Biomolecular Medicine, Faculty of Medicine, Imperial College London, South Kensington, London, SW7 2AZ, UK
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Jochimsen TH, Newbould RD, Skare ST, Clayton DB, Albers GW, Moseley ME, Bammer R. Identifying systematic errors in quantitative dynamic-susceptibility contrast perfusion imaging by high-resolution multi-echo parallel EPI. NMR Biomed 2007; 20:429-38. [PMID: 17044140 PMCID: PMC3985853 DOI: 10.1002/nbm.1107] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [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] [Indexed: 05/12/2023]
Abstract
Several obstacles usually confound a straightforward perfusion analysis using dynamic-susceptibility contrast-based magnetic resonance imaging (DSC-MRI). In this work, it became possible to eliminate some of these sources of error by combining a multiple gradient-echo technique with parallel imaging (PI): first, the large dynamic range of tracer concentrations could be covered satisfactorily with multiple echo times (TE) which would otherwise result in overestimation of image magnitude in the presence of noise. Second, any bias from T(1) relaxation could be avoided by fitting to the signal magnitude of multiple TEs. Finally, with PI, a good tradeoff can be achieved between number of echoes, brain coverage, temporal resolution and spatial resolution. The latter reduces partial voluming, which could distort calculation of the arterial input function. Having ruled out these sources of error, a 4-fold overestimation of cerebral blood volume and flow remained, which was most likely due to the completely different relaxation mechanisms that are effective in arterial voxels compared with tissue. Hence, the uniform tissue-independent linear dependency of relaxation rate upon tracer concentration, which is usually assumed, must be questioned. Therefore, DSC-MRI requires knowledge of the exact dependency of transverse relaxation rate upon tracer concentration in order to calculate truly quantitative perfusion maps.
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Affiliation(s)
- Thies H Jochimsen
- Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr. 1a, D-04103 Leipzig, Germany.
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