OPENCORE NMR: Open-source core modules for implementing an integrated FPGA-based NMR spectrometer

Takeda, Kazuyuki

doi:10.1016/j.jmr.2008.02.019

Cited by 117 publications

(64 citation statements)

References 25 publications

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“…We carried out DNP at the repetition rate of 50 Hz. The NMR experiments and timing control of the DNP, which are shown together with the details of the experimental setup and NMR spectra in SI Text, were programmed with an OPENCORE NMR spectrometer (42,43). The enhancement factor was calculated by comparing the integrated intensities of the 1 H NMR signal S etha of ethanol (40.7 mg) in thermal equilibrium in 0.40 T at 300 K and the hyperpolarized signal S DNP .…”

Section: Methodsmentioning

confidence: 99%

Room temperature hyperpolarization of nuclear spins in bulk

Tateishi

Negoro

Nishida

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

131

161

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Dynamic nuclear polarization (DNP), a means of transferring spin polarization from electrons to nuclei, can enhance the nuclear spin polarization (hence the NMR sensitivity) in bulk materials at most 660 times for 1 H spins, using electron spins in thermal equilibrium as polarizing agents. By using electron spins in photo-excited triplet states instead, DNP can overcome the above limit. We demonstrate a 1 H spin polarization of 34%, which gives an enhancement factor of 250,000 in 0.40 T, while maintaining a bulk sample (∼0.6 mg, ∼0.7 × 0.7 × 1 mm 3 ) containing >10 19 1 H spins at room temperature. Room temperature hyperpolarization achieved with DNP using photo-excited triplet electrons has potentials to be applied to a wide range of fields, including NMR spectroscopy and MRI as well as fundamental physics.N uclear spin is a useful probe for noninvasive analysis of bulk materials such as chemical compounds, industrial products, biological samples, and human bodies. The signal from a spin ensemble is proportional to the polarization P. In thermal equilibrium in a magnetic field B at temperature T, P for spin-1/2 particles is given bywhere Z is the Planck constant, k is the Boltzmann constant, and γ is the gyromagnetic ratio. In a magnetic field of several teslas at room temperature, the nuclear spin energy ZγB=2 is much smaller than the thermal energy kT, so nuclear spins are only slightly polarized. This is the major reason why the sensitivity of NMR spectroscopy and MRI is so low. Dynamic nuclear polarization (DNP) is a means of transferring spin polarization from electrons to nuclei. As a method to enhance the bulk nuclear polarization, DNP has been successfully applied to areas ranging from fundamental physics (1-3) to materials science (4), biology (5-7), and medical science (8), since it was discovered 60 y ago (9, 10). As long as electron spins in thermal equilibrium are used as polarizing agents, the upper limit of the polarization enhancement is 660 for 1 H spins and cryogenic temperatures of around 4.2 K are required for hyperpolarization in the order of 10% even in the strong magnetic fields used for NMR. Hyperpolarization at room temperature will simplify instrumentation and expand the sample variety to materials that prefer ambient temperatures. Other techniques such as optical pumping in semiconductors (11) and the Haupt effect (12) also require cryogenic temperature for increasing bulk polarization beyond 10%.One solution for overcoming the upper limit of the enhancement factor of the conventional DNP, γ e =γ n , is to use nonthermalized electron spins as polarizing agents. A number of organic molecules have photo-excited triplet states where, due to the selection rule in the intersystem crossing from the excited singlet state to the triplet state, the population distribution is highly biased. DNP using electron spins in the photo-excited triplet state can achieve hyperpolarization independent of the magnetic field strength and temperature (13)(14)(15)(16). In this work, we have achieved a bulk hy...

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Section: Methodsmentioning

confidence: 99%

Room temperature hyperpolarization of nuclear spins in bulk

Tateishi

Negoro

Nishida

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

131

161

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“…The primary tradeoff is that the hardware is not optimized for MRI, which necessitated the development of the synchronization methods described here. However, most previously-described MRI spectrometers have been based on new circuit board designs [13, 2, 1, 14, 15, 6, 7, 6] that a user would have to replicate. Furthermore, the only spectrometer with open-sourced hardware schematics is the OPENCORE NMR platform [14, 15], and it does not provide gradient control channels.…”

Section: Discussionmentioning

confidence: 99%

“…For example, spectrometers have been developed in-house to meet the unique needs of low-field MRI scanners [1, 2], deliver point-of-care relaxometry measurements [3], hyperpolarize exogenous contrast agents [4], increase the number of receive channels in parallel imaging [5, 6, 7], implement parallel transmission [7, 8, 9], and acquire signals in NMR field monitoring probes concurrently with imaging [10, 11, 12]. In particular, many recent systems have been designed around field programmable gate arrays (FPGAs) which perform sequencing and signal processing functions [1, 3, 7, 13, 14, 15, 16]. FPGAs are particularly well-suited for MR at Larmor frequencies of tens to hundreds of megahertz since they can process multiple streams of transmitted and received data in parallel at high speeds.…”

Section: Introductionmentioning

confidence: 99%

gr-MRI: A software package for magnetic resonance imaging using software defined radios

Hasselwander

Cao

Grissom

2016

Journal of Magnetic Resonance

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The goal of this work is to develop software that enables the rapid implementation of custom MRI spectrometers using commercially-available software defined radios (SDRs). The developed gr-MRI software package comprises a set of Python scripts, flowgraphs, and signal generation and recording blocks for GNU Radio, an open-source SDR software package that is widely used in communications research. gr-MRI implements basic event sequencing functionality, and tools for system calibrations, multi-radio synchronization, and MR signal processing and image reconstruction. It includes four pulse sequences: a single-pulse sequence to record free induction signals, a gradient-recalled echo imaging sequence, a spin echo imaging sequence, and an inversion recovery spin echo imaging sequence. The sequences were used to perform phantom imaging scans with a 0.5 Tesla tabletop MRI scanner and two commercially-available SDRs. One SDR was used for RF excitation and reception, and the other for gradient pulse generation. The total SDR hardware cost was approximately $2000. The frequency of radio desynchronization events and the frequency with which the software recovered from those events was also measured, and the SDR’s ability to generate frequency-swept RF waveforms was validated and compared to the scanner’s commercial spectrometer. The spin echo images geometrically matched those acquired using the commercial spectrometer, with no unexpected distortions. Desynchronization events were more likely to occur at the very beginning of an imaging scan, but were nearly eliminated if the user invoked the sequence for a short period before beginning data recording. The SDR produced a 500 kHz bandwidth frequency-swept pulse with high fidelity, while the commercial spectrometer produced a waveform with large frequency spike errors. In conclusion, the developed gr-MRI software can be used to develop high-fidelity, low-cost custom MRI spectrometers using commercially-available SDRs.

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“…In situ 7 Li NMR experiments were conducted using a 7 T superconducting magnet and a homebuilt NMR spectrometer [20]. For this study, we developed an in situ 7 Li NMR probe that can charge-discharge the cell while NMR experiments are performed ( Fig.…”

Section: In Situ Nmrmentioning

confidence: 99%

In situ 7Li nuclear magnetic resonance study of the relaxation effect in practical lithium ion batteries

Gotoh

Izuka

Arai

et al. 2014

Carbon

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(Abstract)Lithium ion cells comprising actual components of positive electrodes (LiCoO2, LiNixCoyAlz, and LiMn2O4) and negative electrodes (graphite and hard carbon) were assembled for in situ 7 Li nuclear magnetic resonance (NMR) experiments. The 7 Li NMR measurements of the cells revealed a "relaxation effect" after overcharging: a decrease of the signal assigned to Li metal deposited on the negative electrode surface by overcharging.The reduction of the Li metal signal was inversely proportional to the increase of the signal of lithium stored in carbon. Therefore, the effect was ascribed to absorption of deposited

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OPENCORE NMR: Open-source core modules for implementing an integrated FPGA-based NMR spectrometer

Cited by 117 publications

References 25 publications

Room temperature hyperpolarization of nuclear spins in bulk

Room temperature hyperpolarization of nuclear spins in bulk

gr-MRI: A software package for magnetic resonance imaging using software defined radios

In situ 7Li nuclear magnetic resonance study of the relaxation effect in practical lithium ion batteries

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