Polarization transfer for sensitivity‐enhanced MRS using a single radio frequency transmit channel

Klomp, Dennis W. J.; Kentgens, A.P.M.; Heerschap, Arend

doi:10.1002/nbm.1208

Cited by 20 publications

(19 citation statements)

References 25 publications

(60 reference statements)

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“…A distortionless enhanced polarization transfer (DEPT) sequence for 1 H to 13 C polarization transfer combined with proton image-selected in vivo spectroscopy ( 1 H ISIS) localization (18) was used for acquisition of 13 C magnetic resonance spectra. Adiabatic 13 C radiofrequency pulses were used in all sequences to ensure homogeneous excitation using the 13 C surface coil, as well as wideband alternating phase low-power technique for zero residue splitting (WALTZ-16) proton decoupling (19) to simplify the spectra and enhance signal-to-noise ratio (SNR).…”

Section: Methodsmentioning

confidence: 99%

Effect of Acute Hypoglycemia on Human Cerebral Glucose Metabolism Measured by 13C Magnetic Resonance Spectroscopy

et al. 2011

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OBJECTIVETo investigate the effect of acute insulin-induced hypoglycemia on cerebral glucose metabolism in healthy humans, measured by 13C magnetic resonance spectroscopy (MRS).RESEARCH DESIGN AND METHODSHyperinsulinemic glucose clamps were performed at plasma glucose levels of 5 mmol/L (euglycemia) or 3 mmol/L (hypoglycemia) in random order in eight healthy subjects (four women) on two occasions, separated by at least 3 weeks. Enriched [1-13C]glucose 20% w/w was used for the clamps to maintain stable plasma glucose labeling. The levels of the 13C-labeled glucose metabolites glutamate C4 and C3 were measured over time in the occipital cortex during the clamp by continuous 13C MRS in a 3T magnetic resonance scanner. Time courses of glutamate C4 and C3 labeling were fitted using a one-compartment model to calculate metabolic rates in the brain.RESULTSPlasma glucose 13C isotopic enrichment was stable at 35.1 ± 1.8% during euglycemia and at 30.2 ± 5.5% during hypoglycemia. Hypoglycemia stimulated release of counterregulatory hormones (all P < 0.05) and tended to increase plasma lactate levels (P = 0.07). After correction for the ambient 13C enrichment values, label incorporation into glucose metabolites was virtually identical under both glycemic conditions. Calculated tricarboxylic acid cycle rates (VTCA) were 0.48 ± 0.03 μmol/g/min during euglycemia and 0.43 ± 0.08 μmol/g/min during hypoglycemia (P = 0.42).CONCLUSIONSThese results indicate that acute moderate hypoglycemia does not affect fluxes through the main pathways of glucose metabolism in the brain of healthy nondiabetic subjects.

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Section: Methodsmentioning

confidence: 99%

Effect of Acute Hypoglycemia on Human Cerebral Glucose Metabolism Measured by 13C Magnetic Resonance Spectroscopy

et al. 2011

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“…13 C MRS has been used for several in vitro studies and in vivo investigations on animal models. In addition, increased dynamic lactate production has recently been shown in vivo in a high-grade brain tumor by 13 C MRS using polarization transfer (Klomp et al 2008a) during infusion with 13 C-labeled glucose in a patient (Wijnen et al 2008). Further, 13 C MRS can play an important role in the detection of hyperpolarized compounds.…”

Section: Clinical Applicationsmentioning

confidence: 99%

In vivo magnetic resonance spectroscopy: basic methodology and clinical applications

2009

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The clinical use of in vivo magnetic resonance spectroscopy (MRS) has been limited for a long time, mainly due to its low sensitivity. However, with the advent of clinical MR systems with higher magnetic field strengths such as 3 Tesla, the development of better coils, and the design of optimized radio-frequency pulses, sensitivity has been considerably improved. Therefore, in vivo MRS has become a technique that is routinely used more and more in the clinic. In this review, the basic methodology of in vivo MRS is described—mainly focused on 1H MRS of the brain—with attention to hardware requirements, patient safety, acquisition methods, data post-processing, and quantification. Furthermore, examples of clinical applications of in vivo brain MRS in two interesting fields are described. First, together with a description of the major resonances present in brain MR spectra, several examples are presented of deviations from the normal spectral pattern associated with inborn errors of metabolism. Second, through examples of MR spectra of brain tumors, it is shown that MRS can play an important role in oncology.

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“…Recently, additional signal enhancement has been attained at 3T via refocusing of the homonuclear 1 H-1 H Jcouplings (J SS ) using frequency selective inversion pulses on the proton channel (12). At lower fields such as 1.5T the application of this method will be hindered because of the lower chemical shift dispersion raising the demand for even higher frequency selectivity of the additional pulses.…”

Section: Discussionmentioning

confidence: 99%

3D RINEPT {¹H}‐³¹P CSI: A feasible approach for the study of membrane turnover in the human brain

Wokrina

Ulrich

Weber‐Fahr

2008

Magnetic Resonance in Med

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A fast, full 3D elliptical k-space encoding phosphorous-31 ( 31 P) chemical shift imaging sequence, incorporating heteronuclear polarization transfer editing (RINEPT), was established. RINEPT literally requires simultaneous pulses at the frequencies of both the sensitive and the insensitive nuclei, but only a few MR imaging systems feature a second independent transmit channel. In this study, possible signal degradation of a sequential sequence design on systems featuring a single transmit channel was investigated with spin density matrix calculations and phantom measurements. In addition, metabolite signal intensities were determined in vivo as a function of echo and repetition times. The results enable optimization of the signal-to-noise ratio of one or more metabolites of interest. The results convincingly show that the optimized RINEPT sequence is useful in clinical routine 31 PMRS protocols and provides spectra of excellent quality for the study of cell membrane phospholipid turnover in the human brain even at a low field strength of 1.5T. Phosphomonoesters (PME) and phosphodiesters (PDE) are intermediates of cell membrane phospholipid turnover and thus phosphorous-31 ( 31 P) chemical shift imaging (CSI) of the human brain gains in importance in, e.g., brain diseases that involve membrane defects. At low magnetic field strengths (1.5T or less) the PME and PDE signals are difficult to quantify using standard 31 P CSI. Proton decoupling during acquisition might help to improve spectral resolution; however, spectral quantification is still hampered by the low signal-to-noise ratio (SNR) of these metabolites. In addition, broad macromolecular contributions underlying the PME and PDE resonances obscure the determination of PME and PDE metabolite concentrations (1). The application of multinuclear spectral resolutionenhancing techniques known from high-resolution MR spectroscopy (MRS) is generally limited by the low SNR at field strengths available for clinical routine which lead to long measurement times and/or low spatial resolution. The heteronuclear polarization transfer editing method RINEPT (2) has been previously proposed for in vivo brain studies; however, no spatial localization was obtained (3,4), or measurement times were extremely long (5).In theory RINEPT requires simultaneous RF pulses on both proton 1 H and 31 P frequencies, but only a few MR imaging systems feature a second independent transmit channel. We investigated possible signal degradation by spin density matrix calculations and phantom measurements for the subsequent application of pulses for the two nuclei on a single transmit channel. In addition, human brain RINEPT resonance signals were measured in vivo as a function of a wide range of echo and repetition times on a dual transmit channel system. This allows for directed maximization of the SNR of one or more resonances of interest, depending on the research question. The large chemical shifts of most 31 P metabolites prohibit the application of slice selection pulses or single voxel te...

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Polarization transfer for sensitivity‐enhanced MRS using a single radio frequency transmit channel

Cited by 20 publications

References 25 publications

Effect of Acute Hypoglycemia on Human Cerebral Glucose Metabolism Measured by 13C Magnetic Resonance Spectroscopy

Effect of Acute Hypoglycemia on Human Cerebral Glucose Metabolism Measured by 13C Magnetic Resonance Spectroscopy

In vivo magnetic resonance spectroscopy: basic methodology and clinical applications

3D RINEPT {¹H}‐³¹P CSI: A feasible approach for the study of membrane turnover in the human brain

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Polarization transfer for sensitivity‐enhanced MRS using a single radio frequency transmit channel

Cited by 20 publications

References 25 publications

Effect of Acute Hypoglycemia on Human Cerebral Glucose Metabolism Measured by 13C Magnetic Resonance Spectroscopy

Effect of Acute Hypoglycemia on Human Cerebral Glucose Metabolism Measured by 13C Magnetic Resonance Spectroscopy

In vivo magnetic resonance spectroscopy: basic methodology and clinical applications

3D RINEPT {1H}‐31P CSI: A feasible approach for the study of membrane turnover in the human brain

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3D RINEPT {¹H}‐³¹P CSI: A feasible approach for the study of membrane turnover in the human brain