Simultaneous estimation of T1 and the flip angle in hyperpolarized NMR experiments using acquisition at non-regular time intervals

Puckeridge, Max; Pagès, Guilhem; Kuchel, Philip W.

doi:10.1016/j.jmr.2012.06.006

Cited by 18 publications

(15 citation statements)

References 39 publications

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“…Various NMR methods have been described that provide increased temporal and spatial resolution as well as information content in hyperpolarized probe detection [108–114]. The approaches include modified detection schemes to generate multidimensional spectra from rapid single-scan NMR experiments [54,115–117] or the indirect, amplified detection of signals by saturation transfer methods [86,118].…”

Section: Current Developments and Outlookmentioning

confidence: 99%

Hyperpolarized NMR Probes for Biological Assays

Meier

Jensen

Karlsson

et al. 2014

Sensors

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During the last decade, the development of nuclear spin polarization enhanced (hyperpolarized) molecular probes has opened up new opportunities for studying the inner workings of living cells in real time. The hyperpolarized probes are produced ex situ, introduced into biological systems and detected with high sensitivity and contrast against background signals using high resolution NMR spectroscopy. A variety of natural, derivatized and designed hyperpolarized probes has emerged for diverse biological studies including assays of intracellular reaction progression, pathway kinetics, probe uptake and export, pH, redox state, reactive oxygen species, ion concentrations, drug efficacy or oncogenic signaling. These probes are readily used directly under natural conditions in biofluids and are often directly developed and optimized for cellular assays, thus leaving little doubt about their specificity and utility under biologically relevant conditions. Hyperpolarized molecular probes for biological NMR spectroscopy enable the unbiased detection of complex processes by virtue of the high spectral resolution, structural specificity and quantifiability of NMR signals. Here, we provide a survey of strategies used for the selection, design and use of hyperpolarized NMR probes in biological assays, and describe current limitations and developments.

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Section: Current Developments and Outlookmentioning

confidence: 99%

Hyperpolarized NMR Probes for Biological Assays

Meier

Jensen

Karlsson

et al. 2014

Sensors

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“…Another study 29 calculates flip angles via thermally polarized samples, but the different load of the coil during in vivo study will affect the excitation voltages, which may generate substantial errors. Max et al provided a method 30 for the simultaneous estimation of T 1 and the flip angle in a single scan through acquisition at non-regular time intervals. However, the result of T 1 estimation was significantly affected by the assumed flip angle, and the long acquisition time needed for mounting time intervals also limits its usefulness during in vivo applications.…”

mentioning

confidence: 99%

Fast Determination of Flip Angle and T1 in Hyperpolarized Gas MRI During a Single Breath-Hold

Zhong

Ruan

Han

et al. 2016

Sci Rep

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MRI of hyperpolarized media, such as 129Xe and 3He, shows great potential for clinical applications. The optimal use of the available spin polarization requires accurate flip angle calibrations and T1 measurements. Traditional flip angle calibration methods are time-consuming and suffer from polarization losses during T1 relaxation. In this paper, we propose a method to simultaneously calibrate flip angles and measure T1 in vivo during a breath-hold time of less than 4 seconds. We demonstrate the accuracy, robustness and repeatability of this method and contrast it with traditional methods. By measuring the T1 of hyperpolarized gas, the oxygen pressure in vivo can be calibrated during the same breath hold. The results of the calibration have been applied in variable flip angle (VFA) scheme to obtain a stable steady-state transverse magnetization. Coupled with this method, the ultra-short TE (UTE) and constant VFA (CVFA) schemes are expected to give rise to new applications of hyperpolarized media.

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“…For a more detailed characterization of 4‐pentenoic acid, T 1 measurements were made using a Look–Locker experiment with a flip angle of about 10°, which is a well‐established procedure for relaxation examinations of hyperpolarized samples . Recently presented T 1 estimation experiments might provide more accurate values but will not substantially change the order of magnitude .…”

Section: Resultsmentioning

confidence: 99%

Parahydrogen‐induced polarization of carboxylic acids: a pilot study of valproic acid and related structures

et al. 2014

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Parahydrogen-induced polarization (PHIP) is a promising new tool for medical applications of MR, including MRI. The PHIP technique can be used to transfer high non-Boltzmann polarization, derived from parahydrogen, to isotopes with a low natural abundance or low gyromagnetic ratio (e.g. (13)C), thus improving the signal-to-noise ratio by several orders of magnitude. A few molecules acting as metabolic sensors have already been hyperpolarized with PHIP, but the direct hyperpolarization of drugs used to treat neurological disorders has not been accomplished until now. Here, we report on the first successful hyperpolarization of valproate (valproic acid, VPA), an important and commonly used antiepileptic drug. Hyperpolarization was confirmed by detecting the corresponding signal patterns in the (1)H NMR spectrum. To identify the optimal experimental conditions for the conversion of an appropriate VPA precursor, structurally related molecules with different side chains were analyzed in different solvents using various catalytic systems. The presented results include hyperpolarized (13)C NMR spectra and proton images of related systems, confirming their applicability for MR studies. PHIP-based polarization enhancement may provide a new MR technique to monitor the spatial distribution of valproate in brain tissue and to analyze metabolic pathways after valproate administration.

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Simultaneous estimation of T1 and the flip angle in hyperpolarized NMR experiments using acquisition at non-regular time intervals

Cited by 18 publications

References 39 publications

Hyperpolarized NMR Probes for Biological Assays

Hyperpolarized NMR Probes for Biological Assays

Fast Determination of Flip Angle and T1 in Hyperpolarized Gas MRI During a Single Breath-Hold

Parahydrogen‐induced polarization of carboxylic acids: a pilot study of valproic acid and related structures

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