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Lepucki P, Dioguardi AP, Karnaushenko D, Schmidt OG, Grafe HJ. The normalized limit of detection in NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 332:107077. [PMID: 34634649 DOI: 10.1016/j.jmr.2021.107077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 09/19/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
We derive the normalized limit of detection for frequency space (nLODf) as a parameter to measure the sensitivity of an NMR spectroscopy setup. nLODf is independent of measurement settings such as bandwidth or number of measurement points, and allows to compare performances of different setups. We demonstrate the usefulness of the new nLODf by comparing the sensitivity of NMR setups from various publications, which all use microcoils. Finally, we want to propose a standard measurement and report format for the sensitivity of new NMR setups.
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Affiliation(s)
- Piotr Lepucki
- IFW Dresden, Institut für Festkörperforschung, Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Adam P Dioguardi
- IFW Dresden, Institut für Festkörperforschung, Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Daniil Karnaushenko
- IFW Dresden, Institut für Integrative Nanowissenschaften, Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Oliver G Schmidt
- IFW Dresden, Institut für Integrative Nanowissenschaften, Helmholtzstraße 20, 01069 Dresden, Germany; TU Dresden, Nanophysik, Häckelstraße 3, 01069 Dresden, Germany; TU Chemnitz, Material Systems for Nanoelectronics, Straße der Nationen 62, 09111 Chemnitz, Germany.
| | - Hans-Joachim Grafe
- IFW Dresden, Institut für Festkörperforschung, Helmholtzstraße 20, 01069 Dresden, Germany.
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Deborne J, Pinaud N, Crémillieux Y. Proton MRS on sub-microliter volume in rat brain using implantable NMR microcoils. NMR IN BIOMEDICINE 2021; 34:e4578. [PMID: 34189772 DOI: 10.1002/nbm.4578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/20/2021] [Accepted: 06/09/2021] [Indexed: 06/13/2023]
Abstract
The use of miniaturized NMR receiver coils is an effective approach for improving detection sensitivity in studies using MRS and MRI. By optimizing the filling factor (the fraction of the coil occupied by the sample), and by increasing the RF magnetic field produced per unit current, the sensitivity gain offered by NMR microcoils is particularly interesting when small volumes or regions of interest are investigated. For in vivo studies, millimetric or sub-millimetric microcoils can be deployed in tissues to access regions of interest located at a certain depth. In this study, the implementation and application of a tissue-implantable NMR microcoil with a detection volume of 850 nL is described. The RF magnetic field generated by the microcoil was evaluated using a finite element method simulation and experimentally determined by high spatial resolution MRI acquisitions. The performance of the microcoil in terms of spectral resolution and limit of detection was measured at 7 T in vitro and in vivo in rodent brains. These performances were compared with those of a conventional external detection coil. Proton MR spectra were acquired in the cortex of rat brain. The concentrations of main metabolites were quantified and compared with reference values from the literature. In vitro and in vivo results obtained with the implantable microcoil showed a gain in sensitivity greater than 50 compared with detection using an external coil. In vivo proton spectra of diagnostic value were obtained from brain regions of a few hundred nanoliters. The similarities between spectra obtained with the implanted microcoil and those obtained with the external NMR coil highlight the minimally invasive nature of the coil implantation procedure. These implantable microcoils represent new tools for probing tissue metabolism in very small healthy or diseased regions using MRS.
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Affiliation(s)
- Justine Deborne
- Institut des Sciences Moléculaires, Université de Bordeaux, Bordeaux, France
| | - Noël Pinaud
- Institut des Sciences Moléculaires, Université de Bordeaux, Bordeaux, France
| | - Yannick Crémillieux
- Institut des Sciences Moléculaires, Université de Bordeaux, Bordeaux, France
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Implantable NMR Microcoils in Rats: A New Tool for Exploring Tumor Metabolism at Sub-Microliter Scale? Metabolites 2021; 11:metabo11030176. [PMID: 33803055 PMCID: PMC8002894 DOI: 10.3390/metabo11030176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/08/2021] [Accepted: 03/12/2021] [Indexed: 12/18/2022] Open
Abstract
The aim of this study was to evaluate the potential of a miniaturized implantable nuclear magnetic resonance (NMR) coil to acquire in vivo proton NMR spectra in sub-microliter regions of interest and to obtain metabolic information using magnetic resonance spectroscopy (MRS) in these small volumes. For this purpose, the NMR microcoils were implanted in the right cortex of healthy rats and in C6 glioma-bearing rats. The dimensions of the microcoil were 450 micrometers wide and 3 mm long. The MRS acquisitions were performed at 7 Tesla using volume coil for RF excitation and microcoil for signal reception. The detection volume of the microcoil was measured equal to 450 nL. A gain in sensitivity equal to 76 was found in favor of implanted microcoil as compared to external surface coil. Nine resonances from metabolites were assigned in the spectra acquired in healthy rats (n = 5) and in glioma-bearing rat (n = 1). The differences in relative amplitude of choline, lactate and creatine resonances observed in glioma-bearing animal were in agreement with published findings on this tumor model. In conclusion, the designed implantable microcoil is suitable for in vivo MRS and can be used for probing the metabolism in localized and very small regions of interest in a tumor.
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Chen J, You X, Sun H, Tian J, Fang H, Xie J, Huang Y, Chen Z. Optimization of twin parallel microstrips based nuclear magnetic resonance probe for measuring the kinetics in molecular assembly in ultra-small samples. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033106. [PMID: 33820024 DOI: 10.1063/5.0030452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 02/26/2021] [Indexed: 06/12/2023]
Abstract
We present the design, fabrication, characterization, and optimization of a TPM (twin parallel microstrip)-based nuclear magnetic resonance (NMR) probe, produced by using a low-loss Teflon PTFE F4B high frequency circuit board. We use finite element analysis to optimize the radio frequency (RF) homogeneity and sensitivity of the TPM probe jointly for various sample volumes. The RF homogeneity of this TPM planar probe is superior to that of only a single microstrip probe. The optimized TPM probe properties such as RF homogeneity and field strength are characterized experimentally and discussed in detail. By combining this TPM based NMR probe with microfluidic technology, the sample amount required for kinetic study using NMR spectroscopy was minimized. This is important for studying costly samples. The TPM NMR probes provide high sensitivity to analysis of 5 µl samples with 2 mM concentrations within 10 min. The miniaturized microfluidic NMR probe plays an important role in realizing down to seconds timescale for kinetic monitoring.
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Affiliation(s)
- Jiahe Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Xueqiu You
- School of Information Engineering, Jimei University, Xiamen 361021, People's Republic of China
| | - Huijun Sun
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Jiaqin Tian
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Hongxun Fang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China
| | - Junyao Xie
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Yuqing Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, People's Republic of China
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Kollmeier AS, de la Torre X, Müller C, Botrè F, Parr MK. In-depth gas chromatography/tandem mass spectrometry fragmentation analysis of formestane and evaluation of mass spectral discrimination of isomeric 3-keto-4-ene hydroxy steroids. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8937. [PMID: 32876355 DOI: 10.1002/rcm.8937] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/27/2020] [Accepted: 08/28/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE The aromatase inhibitor formestane (4-hydroxyandrost-4-ene-3,17-dione) is included in the World Anti-Doping Agency's List of Prohibited Substances in Sport. However, it also occurs endogenously as do its 2-, 6- and 11-hydroxy isomers. The aim of this study is to distinguish the different isomers using gas chromatography/electron ionization mass spectrometry (GC/EI-MS) for enhanced confidence in detection and selectivity for determination. METHODS Established derivatization protocols to introduce [2 H9 ]TMS were followed to generate perdeuterotrimethylsilylated and mixed deuterated derivatives for nine different hydroxy steroids, all with 3-keto-4-ene structure. Formestane was additionally labelled with H2 18 O to obtain derivatives doubly labelled with [2 H9 ]TMS and 18 O. GC/EI-MS spectra of labelled and unlabelled TMS derivatives were compared. Proposals for the generation of fragment ions were substantiated by high-resolution MS (GC/QTOFMS) and tandem mass spectrometry (MS/MS) experiments. RESULTS Subclass-specific fragment ions include m/z 319 for the 6-hydroxy and m/z 219 for the 11-hydroxy compounds. Ions at m/z 415, 356, 341, 313, 269 and 267 were indicative for the 2- and 4-hydroxy compounds. For their discrimination the transition m/z 503 → 269 was selective for formestane. In 2-, 4- and 6-hydroxy steroids loss of a TMSO radical takes place as cleavage of a TMS-derived methyl radical and a neutral loss of (CH3 )2 SiO. Further common fragments were also elucidated. CONCLUSIONS With the help of stable isotope labelling, the structures of postulated diagnostic fragment ions for the different steroidal subclasses were elucidated. 18 O-labelling of the other compounds will be addressed in future studies to substantiate the obtained findings. To increase method sensitivity MS3 may be suitable in future bioanalytical applications requiring discrimination of the 2- and 4-hydroxy compounds.
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Affiliation(s)
| | | | - Christian Müller
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstr. 34-36, Berlin, 14195, Germany
| | - Francesco Botrè
- Laboratorio Antidoping FSMI, Largo Giulio Onesti 1, Rome, 00197, Italy
| | - Maria Kristina Parr
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, Berlin, 14195, Germany
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Design of High Performance Scroll Microcoils for Nuclear Magnetic Resonance Spectroscopy of Nanoliter and Subnanoliter Samples. SENSORS 2020; 21:s21010170. [PMID: 33383815 PMCID: PMC7795071 DOI: 10.3390/s21010170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/18/2020] [Accepted: 12/20/2020] [Indexed: 01/05/2023]
Abstract
The electromagnetic properties of scroll microcoils are investigated with finite element modelling (FEM) and the design of experiment (DOE) approach. The design of scroll microcoils was optimized for nuclear magnetic resonance (NMR) spectroscopy of nanoliter and subnanoliter sample volumes. The unusual proximity effect favours optimised scroll microcoils with a large number of turns rolled up in close proximity. Scroll microcoils have many advantages over microsolenoids: such as ease of fabrication and better B1-homogeneity for comparable intrinsic signal-to-noise ratio (SNR). Scroll coils are suitable for broadband multinuclei NMR spectroscopy of subnanoliter sample.
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Göbel K, Gruschke OG, Leupold J, Kern JS, Has C, Bruckner-Tuderman L, Hennig J, von Elverfeldt D, Baxan N, Korvink JG. Phased-array of microcoils allows MR microscopy ofex vivohuman skin samples at 9.4 T. Skin Res Technol 2014; 21:61-8. [DOI: 10.1111/srt.12157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2014] [Indexed: 11/28/2022]
Affiliation(s)
- K. Göbel
- Department of Radiology; Medical Physics; University Medical Center Freiburg; Freiburg Germany
| | - O. G. Gruschke
- Laboratory of Simulation; IMTEK; University of Freiburg; Freiburg Germany
| | - J. Leupold
- Department of Radiology; Medical Physics; University Medical Center Freiburg; Freiburg Germany
| | - J. S. Kern
- Department of Dermatology; University Medical Center Freiburg; Freiburg Germany
| | - C. Has
- Department of Dermatology; University Medical Center Freiburg; Freiburg Germany
| | | | - J. Hennig
- Department of Radiology; Medical Physics; University Medical Center Freiburg; Freiburg Germany
| | - D. von Elverfeldt
- Department of Radiology; Medical Physics; University Medical Center Freiburg; Freiburg Germany
| | - N. Baxan
- Bruker BioSpin MRI GmbH; Ettlingen Germany
| | - J. G. Korvink
- Laboratory of Simulation; IMTEK; University of Freiburg; Freiburg Germany
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Gruschke OG, Baxan N, Clad L, Kratt K, von Elverfeldt D, Peter A, Hennig J, Badilita V, Wallrabe U, Korvink JG. Lab on a chip phased-array MR multi-platform analysis system. LAB ON A CHIP 2012; 12:495-502. [PMID: 22200053 DOI: 10.1039/c2lc20585h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a lab on a chip (LOC) compatible modular platform for magnetic resonance (MR)-based investigation of sub-millimetre samples. The platform combines the advantages offered respectively by microcoils (high resolution at the microscale) and macroscopic surface coils (large field of view) as MR-detectors and consists of a phased array of microcoils (PAMs) providing a flat MR-sensitive area of 18.3 mm(2) with a B(0)-field uniformity better than 0.25 ppm in the sensor centre area. We demonstrate both high-resolution magnetic resonance imaging (MRI) and NMR spectroscopy using this platform. To demonstrate the application for biological samples, we report MR imaging of fish oocytes with an in-plane resolution of 30 × 30 μm(2) and a contrast to noise ratio of 10 for a scan time of only 13 min 39 s. We have also demonstrated high-resolution spectroscopy of a water phantom achieving 11 ppb (4.5 Hz at 400 MHz) linewidth and an SNR of 28 for only 12 s scan time. State of the art automatic wire bonding technology in conjunction with MEMS techniques has been employed to manufacture the platform with potential applications in MR-investigation of planar samples.
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Affiliation(s)
- Oliver G Gruschke
- University of Freiburg, Department of Microsystems Engineering (IMTEK), Lab of Simulation, Georges-Köhler-Allee 103, 79110 Freiburg, Germany.
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Baxan N, Kahlert U, Maciaczyk J, Nikkhah G, Hennig J, von Elverfeldt D. Microcoil-based MR phase imaging and manganese enhanced microscopy of glial tumor neurospheres with direct optical correlation. Magn Reson Med 2011; 68:86-97. [PMID: 22127877 DOI: 10.1002/mrm.23208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2010] [Revised: 07/06/2011] [Accepted: 08/16/2011] [Indexed: 12/22/2022]
Abstract
Susceptibility differences among tissues were recently used for highlighting complementary contrast in MRI different from the conventional T(1), T(2), or spin density contrasts. This method, based on the signal phase, previously showed improved image contrast of human or rodent neuroarchitecture in vivo, although direct MR phase imaging of cellular architecture was not available until recently. In this study, we present for the first time the ability of microcoil-based phase MRI to resolve the structure of human glioma neurospheres at significantly improved resolutions (10 × 10 μm(2)) with direct optical image correlation. The manganese chloride property to function as a T(1) contrast agent enabled a closer examination of cell physiology with MRI. Specifically the temporal changes of manganese chloride uptake, retention and release time within and from individual clusters were assessed. The optimal manganese chloride concentration for improved MR signal enhancement was determined while keeping the cellular viability unaffected. The presented results demonstrate the possibilities to reveal structural and functional observation of living glioblastoma human-derived cells. This was achieved through the combination of highly sensitive microcoils, high magnetic field, and methods designed to maximize contrast to noise ratio. The presented approach may provide a powerful multimodal tool that merges structural and functional information of submilimeter biological samples.
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Affiliation(s)
- Nicoleta Baxan
- Department of Radiology, Medical Physics, University Medical Center, Freiburg, Germany.
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Weber H, Baxan N, Paul D, Maclaren J, Schmidig D, Mohammadzadeh M, Hennig J, von Elverfeldt D. Microcoil-based MRI: feasibility study and cell culture applications using a conventional animal system. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2011; 24:137-45. [PMID: 21331647 DOI: 10.1007/s10334-011-0244-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 01/10/2011] [Accepted: 01/24/2011] [Indexed: 12/22/2022]
Abstract
OBJECT The aim of this study was to demonstrate the feasibility of MR microimaging on a conventional 9.4 T horizontal animal MRI system using commercial available microcoils in combination with only minor modifications to the system, thereby opening this field to a larger community. MATERIALS AND METHODS Commercially available RF microcoils designed for high-resolution NMR spectrometers were used in combination with a custom-made probehead. For this purpose, changes within the transmit chain and modifications to the adjustment routines and image acquisition sequences were made, all without requiring expensive hardware. To investigate the extent to which routine operation and high-resolution imaging is possible, the quality of phantom images was analysed. Surface and solenoidal microcoils were characterized with regard to their sensitive volume and signal-to-noise ratio. In addition, the feasibility of using planar microcoils to achieve high-resolution images of living glioma cells labelled with MnCl(2) was investigated. RESULTS The setup presented in this work allows routine acquisition of high-quality images with high SNR and isotropic resolutions up to 10 μm within an acceptable measurement time. CONCLUSION This study demonstrates that MR microscopy can be applied at low cost on animal MR imaging systems, which are in widespread use. The successful imaging of living glioma cells indicates that the technique promises to be a useful tool in biomedical research.
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Affiliation(s)
- Hans Weber
- Medical Physics, Department of Radiology, University Medical Center Freiburg, Breisacher Str. 60a, 79106, Freiburg, Germany.
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Bart J, Janssen JWG, van Bentum PJM, Kentgens APM, Gardeniers JGE. Optimization of stripline-based microfluidic chips for high-resolution NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 201:175-185. [PMID: 19786359 DOI: 10.1016/j.jmr.2009.09.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 08/26/2009] [Accepted: 09/04/2009] [Indexed: 05/28/2023]
Abstract
We here report on the optimization, fabrication and experimental characterization of a stripline-based microfluidic NMR probe, realized in a silicon substrate. The stripline geometry was modelled in respect of rf-homogeneity, sensitivity and spectral resolution. Using these models, optimal dimensional ratios were found, which hold for every sample size. Based on the optimized parameters, a simple integrated stripline-based microfluidic chip was realized. The fabrication of this chip is described in detail. We achieved a sensitivity of 0.47 nmol/square root(Hz) and a resolution of 0.7 Hz. The rf-homogeneity (A(810 degrees)/A(90 degrees)) was 76% and was proved to be suitable for 2D-NMR analysis of glucose.
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Affiliation(s)
- J Bart
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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