Determination of Total Tissue Sodium Concentrations by Use of Radiosodium

Green, D. M.; Reynolds, Telfer B.; Girerd, R. J.

doi:10.1161/01.res.3.4.330

Cited by 6 publications

(4 citation statements)

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“…The average TSC in soft tissues is 40 mM (15), with TSC values varying between 20 mM and 60 mM for different tissues. For example, TSC values of 20 mM in muscle, 25 mM in spleen, 30 mM in liver, 40 mM in heart and brain, 50 mM in stomach, and 60 mM in kidney (15) have been reported. Given our experience in performing very accurate FA calibrations at the sodium frequency in rat brains (average concentration ϭ 40 mM; results displayed in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The main advantage of this approach is that a high enough tissue sodium concentration (TSC) exists in most live tissues to allow for accurate FA calibration at this frequency using endogenous signal. The average TSC in soft tissues is 40 mM (15), with TSC values varying between 20 mM and 60 mM for different tissues. For example, TSC values of 20 mM in muscle, 25 mM in spleen, 30 mM in liver, 40 mM in heart and brain, 50 mM in stomach, and 60 mM in kidney (15) have been reported.…”

Section: Discussionmentioning

confidence: 99%

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Accurate flip‐angle calibration for ¹³C MRI

Hancu

Watkins

Kohler

et al. 2007

Magnetic Resonance in Med

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13 C imaging and spectroscopy in the presence of injected labeled compounds can vastly extend the capability of MRI to perform metabolic imaging. The details of imaging in the presence of injected compounds, however, pose new technological challenges. Pulse sequences, in general, rely on precise flipangle (FA) calibration to create high signal-to-noise ratio (SNR), artifact-free images. Signal quantification also requires precise knowledge of the excitation FA. In MRI scans that rely on signal acquisitions from injected compounds, however, such FA calibration is challenged by low natural-abundance 13 C signal levels before injection, and by time-varying signal following injection. A method to precisely set the FA at the 13 Given the ubiquitous presence of carbon atoms in most metabolic processes, and the large chemical shift range of the 13 C nuclei, 13 C spectroscopy is very promising for following metabolism in vivo. Static or dynamic 13 C images or spectra from animals and humans have been reported using both natural abundance and infusion of 13 C labeled compounds (1-6). Given the low gyromagnetic ratio of the 13 C nuclei, however, even images/spectra aided by the infusion of labeled compounds suffer from limited spatial resolution and low signal-to-noise ratio (SNR) at infusion doses and imaging times compatible with a routine clinical exam.The recent development of hyperpolarization techniques (7,8) can dramatically change the impact that 13 C MRI and MRS can have in managing a variety of pathological conditions. Real-time imaging of metabolism has been reported in a variety of animal models of disease using MRI of 13 C labeled, hyperpolarized compounds (9 -12). In order to successfully translate the results of research performed in animals to humans, care must be taken when imaging such compounds to ensure that the maximum information is extracted using the minimum relevant agent dose. The hyperpolarized signals are large, nonrenewable, and fast decaying, and require special attention when imaged to extract the maximum image SNR per injected agent dose.Many pulse sequences require precise flip-angle (FA) calibration to produce high-SNR, artifact-free images. Moreover, quantification of compound concentration relies on precise knowledge of the excitation FA. For most MRI or MRS scans, FA calibration is performed in a prescan step, at the same frequency as the one used for imaging. For infusion or injection of 13 C labeled (or labeled and hyperpolarized) compounds, such a calibration step is challenged by the low availability of natural-abundance signal prior to injection, and by the variable nature of the signal following injection. One approach to overcome these difficulties is to use a phantom that loads the coil in a manner similar to that in which a patient would load it, and perform a FA calibration on that phantom prior to any patient scan. The same transmit gain (TG) setting would then be used for all of the in vivo studies. However, in 23 Na scans of human brains, for example, the transmit power c...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Accurate flip‐angle calibration for ¹³C MRI

Hancu

Watkins

Kohler

et al. 2007

Magnetic Resonance in Med

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“…; Green et al. ) or more recently, magnetic resonance spectroscopy (Christensen et al. ; Kopp et al.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, these measurements are typically confined to liquid samples, that is, cerebrospinal fluid and/or serum/ plasma. Tissue measurements usually involve radiolabeled nuclei (Christensen et al 1996;Green et al 1955) or more recently, magnetic resonance spectroscopy (Christensen et al 1996;Kopp et al 2012;Reetz et al 2012;Wang et al 2013;Yushmanov et al 2007), although other techniques such as ashing followed by flame photometry have been implemented (Titze et al 2005(Titze et al , 2002.…”

Section: Introductionmentioning

confidence: 99%

Measurement of cations, anions, and acetate in serum, urine, cerebrospinal fluid, and tissue by ion chromatography

et al. 2018

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Accurate quantification of cations and anions remains a major diagnostic tool in understanding diseased states. The current technologies used for these analyses are either unable to quantify all ions due to sample size/volume, instrument setup/method, or are only able to measure ion concentrations from one physiological sample (liquid or solid). Herein, we adapted a common analytical chemistry technique, ion chromatography and applied it to measure the concentration of cations; sodium, potassium, calcium, and magnesium (Na+, K+, Ca2+, and Mg2+) and anions; chloride, and acetate (Cl−, − OAc) from physiological samples. Specifically, cations and anions were measured in liquid samples: serum, urine, and cerebrospinal fluid, as well as tissue samples: liver, cortex, hypothalamus, and amygdala. Serum concentrations of Na+, K+, Ca2+, Mg2+, Cl−, and − OAc (mmol/L): 138.8 ± 4.56, 4.05 ± 0.21, 4.07 ± 0.26, 0.98 ± 0.05, 97.7 ± 3.42, and 0.23 ± 0.04, respectively. Cerebrospinal fluid concentrations of Na+, K+, Ca2+, Mg2+, Cl−, and − OAc (mmol/L): 145.1 ± 2.81, 2.41 ± 0.26, 2.18 ± 0.38, 1.04 ± 0.11, 120.2 ± 3.75, 0.21 ± 0.05, respectively. Tissue Na+, K+, Ca2+, Mg2+, Cl−, and − OAc were also measured. Validation of the ion chromatography method was established by comparing chloride concentration between ion chromatography with a known method using an ion selective chloride electrode. These results indicate that ion chromatography is a suitable method for the measurement of cations and anions, including acetate from various physiological samples.

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