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1.
Ladislav Valkovič Marek Chmelík Ivica Just Kukurová Michaela Jakubová Monika Christina Kipfelsberger Patrik Krumpolec Marjeta Tušek Jelenc Wolfgang Bogner Martin Meyerspeer Jozef Ukropec Ivan Frollo Barbara Ukropcová Siegfried Trattnig Martin Krššák 《NMR in biomedicine》2014,27(11):1346-1352
Dynamic 31P‐MRS with sufficiently high temporal resolution enables the non‐invasive evaluation of oxidative muscle metabolism through the measurement of phosphocreatine (PCr) recovery after exercise. Recently, single‐voxel localized 31P‐MRS was compared with surface coil localization in a dynamic fashion, and was shown to provide higher anatomical and physiological specificity. However, the relatively long TE needed for the single‐voxel localization scheme with adiabatic pulses limits the quantification of J‐coupled spin systems [e.g. adenosine triphosphate (ATP)]. Therefore, the aim of this study was to evaluate depth‐resolved surface coil MRS (DRESS) as an alternative localization method capable of free induction decay (FID) acquisition for dynamic 31P‐MRS at 7 T. The localization performance of the DRESS sequence was tested in a phantom. Subsequently, two dynamic examinations of plantar flexions at 25% of maximum voluntary contraction were conducted in 10 volunteers, one examination with and one without spatial localization. The DRESS slab was positioned obliquely over the gastrocnemius medialis muscle, avoiding other calf muscles. Under the same load, significant differences in PCr signal drop (31.2 ± 16.0% versus 43.3 ± 23.4%), end exercise pH (7.06 ± 0.02 versus 6.96 ± 0.11), initial recovery rate (0.24 ± 0.13 mm /s versus 0.35 ± 0.18 mm /s) and maximum oxidative flux (0.41 ± 0.14 mm /s versus 0.54 ± 0.16 mm /s) were found between the non‐localized and DRESS‐localized data, respectively. Splitting of the inorganic phosphate (Pi) signal was observed in several non‐localized datasets, but in none of the DRESS‐localized datasets. Our results suggest that the application of the DRESS localization scheme yielded good spatial selection, and provided muscle‐specific insight into oxidative metabolism, even at a relatively low exercise load. In addition, the non‐echo‐based FID acquisition allowed for reliable detection of ATP resonances, and therefore calculation of the specific maximum oxidative flux, in the gastrocnemius medialis using standard assumptions about resting ATP concentration in skeletal muscle. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
2.
J. Löring W. J. M. van der Kemp S. Almujayyaz J. W. M. van Oorschot P. R. Luijten D. W. J. Klomp 《NMR in biomedicine》2016,29(6):709-720
Widespread use of ultrahigh‐field 31P MRSI in clinical studies is hindered by the limited field of view and non‐uniform radiofrequency (RF) field obtained from surface transceivers. The non‐uniform RF field necessitates the use of high specific absorption rate (SAR)‐demanding adiabatic RF pulses, limiting the signal‐to‐noise ratio (SNR) per unit of time. Here, we demonstrate the feasibility of using a body‐sized volume RF coil at 7 T, which enables uniform excitation and ultrafast power calibration by pick‐up probes. The performance of the body coil is examined by bench tests, and phantom and in vivo measurements in a 7‐T MRI scanner. The accuracy of power calibration with pick‐up probes is analyzed at a clinical 3‐T MR system with a close to identical 1H body coil integrated at the MR system. Finally, we demonstrate high‐quality three‐dimensional 31P MRSI of the human body at 7 T within 5 min of data acquisition that includes RF power calibration. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
3.
4.
Repeatability of 31P MRSI in the human brain at 7 T with and without the nuclear Overhauser effect
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Miriam W. Lagemaat Bart L. van de Bank Pascal Sati Shizhe Li Marnix C. Maas Tom W. J. Scheenen 《NMR in biomedicine》2016,29(3):256-263
An often‐employed strategy to enhance signals in 31P MRS is the generation of the nuclear Overhauser effect (NOE) by saturation of the water resonance. However, NOE allegedly increases the variability of the 31P data, because variation is reported in NOE enhancements. This would negate the signal‐to‐noise (SNR) gain it generates. We hypothesized that the variation in NOE enhancement values is not caused by the variability in NOE itself, but is attributable to measurement uncertainties in the values used to calculate the enhancement. If true, the expected increase in SNR with NOE would improve the repeatability of 31P MRS measurements. To verify this hypothesis, a repeatability study of native and NOE‐enhanced 31P MRSI was performed in the brains of seven healthy volunteers at 7 T. The repeatability coefficient (RC) and the coefficient of variation in repeated measurements (CoVrepeat) were determined for each method, and the 95% limits of agreement (LoAs) between native and NOE‐enhanced signals were calculated. The variation between the methods, defined by the LoA, is at least as great as that predicted by the RC of each method. The sources of variation in NOE enhancements were determined using variance component analysis. In the seven metabolites with a positive NOE enhancement (nine metabolite resonances assessed), CoVrepeat improved, on average, by 15%. The LoAs could be explained by the RCs of the individual methods for the majority of the metabolites, generally confirming our hypothesis. Variation in NOE enhancement was mainly attributable to the factor repeat, but between‐voxel effects were also present for phosphoethanolamine and (glycero)phosphocholine. CoVrepeat and fitting error were strongly correlated and improved with positive NOE. Our findings generally indicate that NOE enhances the signal of metabolites, improving the repeatability of metabolite measurements. Additional variability as a result of NOE was minimal. These findings encourage the use of NOE‐enhanced 31P MRSI. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
Feasibility and repeatability of localized 31P‐MRS four‐angle saturation transfer (FAST) of the human gastrocnemius muscle using a surface coil at 7 T
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Marjeta Tušek Jelenc Marek Chmelík Wolfgang Bogner Martin Krššák Siegfried Trattnig Ladislav Valkovič 《NMR in biomedicine》2016,29(1):57-65
Phosphorus (31P) MRS, combined with saturation transfer (ST), provides non‐invasive insight into muscle energy metabolism. However, even at 7 T, the standard ST method with T1app measured by inversion recovery takes about 10 min, making it impractical for dynamic examinations. An alternative method, i.e. four‐angle saturation transfer (FAST), can shorten the examination time. The aim of this study was to test the feasibility, repeatability, and possible time resolution of the localized FAST technique measurement on an ultra‐high‐field MR system, to accelerate the measurement of both Pi‐to‐ATP and PCr‐to‐ATP reaction rates in the human gastrocnemius muscle and to test the feasibility of using the FAST method for dynamic measurements. We measured the exchange rates and metabolic fluxes in the gastrocnemius muscle of eight healthy subjects at 7 T with the depth‐resolved surface coil MRS (DRESS)‐localized FAST method. For comparison, a standard ST localized method was also used. The measurement time for the localized FAST experiment was 3.5 min compared with the 10 min for the standard localized ST experiment. In addition, in five healthy volunteers, Pi‐to‐ATP and PCr‐to‐ATP metabolic fluxes were measured in the gastrocnemius muscle at rest and during plantar flexion by the DRESS‐localized FAST method. The repeatability of PCr‐to‐ATP and Pi‐to‐ATP exchange rate constants, determined by the slab‐selective localized FAST method at 7 T, is high, as the coefficients of variation remained below 20%, and the results of the exchange rates measured with the FAST method are comparable to those measured with standard ST. During physical activity, the PCr‐to‐ATP metabolic flux decreased (from FCK = 8.21 ± 1.15 mM s?1 to FCK = 3.86 ± 1.38 mM s?1) and the Pi‐to‐ATP flux increased (from FATP = 0.43 ± 0.14 mM s?1 to FATP = 0.74 ± 0.13 mM s?1). In conclusion, we could demonstrate that measurements in the gastrocnemius muscle are feasible at rest and are short enough to be used during exercise with the DRESS‐localized FAST method at 7 T. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. 相似文献
6.
Bart L. van de Bank Stephan Orzada Frits Smits Miriam W. Lagemaat Christopher T. Rodgers Andreas K. Bitz Tom W. J. Scheenen 《NMR in biomedicine》2015,28(11):1570-1578
The design and construction of a dedicated RF coil setup for human brain imaging (1H) and spectroscopy (31P) at ultra‐high magnetic field strength (7 T) is presented. The setup is optimized for signal handling at the resonance frequencies for 1H (297.2 MHz) and 31P (120.3 MHz). It consists of an eight‐channel 1H transmit–receive head coil with multi‐transmit capabilities, and an insertable, actively detunable 31P birdcage (transmit–receive and transmit only), which can be combined with a seven‐channel receive‐only 31P array. The setup enables anatomical imaging and 31P studies without removal of the coil or the patient. By separating transmit and receive channels and by optimized addition of array signals with whitened singular value decomposition we can obtain a sevenfold increase in SNR of 31P signals in the occipital lobe of the human brain compared with the birdcage alone. These signals can be further enhanced by 30 ± 9% using the nuclear Overhauser effect by B1‐shimmed low‐power irradiation of water protons. Together, these features enable acquisition of 31P MRSI at high spatial resolutions (3.0 cm3 voxel) in the occipital lobe of the human brain in clinically acceptable scan times (~15 min). © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. 相似文献
7.
J. P. Wijnen L. Jiang T. R. Greenwood M. Cheng M. Döpkens M. D. Cao Z.M. Bhujwalla B. Krishnamachary D. W. J. Klomp K. Glunde 《NMR in biomedicine》2014,27(6):692-699
Abnormal choline phospholipid metabolism is an emerging hallmark of cancer, which is implicated in carcinogenesis and tumor progression. The malignant metabolic phenotype is characterized by high levels of phosphocholine (PC) and relatively low levels of glycerophosphocholine (GPC) in aggressive breast cancer cells. Phosphorus (31P) MRS is able to non‐invasively detect these water‐soluble metabolites of choline as well as ethanolamine phospholipid metabolism. Here we have investigated the effects of stably silencing glycerophosphoester diesterase domain containing 5 (GDPD5), which is an enzyme with glycerophosphocholine phosphodiesterase activity, in MDA‐MB‐231 breast cancer cells and orthotopic tumor xenografts. Tumors in which GDPD5 was stably silenced with GDPD5‐specific shRNA contained increased levels of GPC and phosphoethanolamine (PE) compared with control tumors. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
J.‐H. Chen R.S. Mehta H.‐M. Baek K. Nie H. Liu M.Q. Lin H.J. Yu O. Nalcioglu M.‐Y. Su 《NMR in biomedicine》2011,24(3):316-324
This study investigated the association between the total choline (tCho) concentration and the clinical characteristics and biomarker status of breast cancer. Sixty‐two patients with breast cancer, 1.5 cm or larger in size on MR images, were studied. The tCho concentration was correlated with the MRI features, contrast enhancement kinetics, clinical variables and biomarkers. Pairwise two‐tailed Spearman's nonparametric test was used for statistical analysis. The tCho concentration was higher in high‐grade than moderate‐/low‐grade tumors (p = 0.04) and in tumors with higher Ktrans and kep (p < 0.001 for both). The association of tCho concentration with age (p = 0.05) and triple negative biomarker (p = 0.09) approached significance. tCho was not detected in 17 patients, including 15 with invasive ductal cancer and two with infiltrating lobular cancer. Fifteen of the 17 patients had moderate‐ to low‐grade cancers, and 11 had human epidermal growth factor‐2‐negative cancer, suggesting that these two factors might lead to false‐negative choline. Higher tCho concentration in high‐grade tumors and tumors with higher Ktrans and kep indicates that choline is associated with cell proliferation and tumor angiogenesis. The higher choline level in younger women may be caused by their more aggressive tumor type. The results presented here may aid in the better interpretation of 1H MRS for the diagnosis of breast lesions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
9.
W. J. M. van der Kemp V. O. Boer P. R. Luijten B. L. Stehouwer W. B. Veldhuis D. W. J. Klomp 《NMR in biomedicine》2013,26(10):1299-1307
An adiabatic multi‐echo spectroscopic imaging (AMESING) sequence, used for 31P MRSI, with spherical k‐space sampling and compensated phase‐encoding gradients, was implemented on a whole‐body 7‐T MR system. One free induction decay (FID) and up to five symmetric echoes can be acquired with this sequence. In tissues with low T2* and high T2, this can theoretically lead to a potential maximum signal‐to‐noise ratio (SNR) increase of almost a factor of three, compared with a conventional FID acquisition with Ernst‐angle excitation. However, with T2 values being, in practice, ≤400 ms, a maximum enhancement of approximately two compared with low flip Ernst‐angle excitation should be feasible. The multi‐echo sequence enables the determination of localized T2 values, and was validated with 31P three‐dimensional MRSI on the calf muscle and breast of a healthy volunteer, and subsequently applied in a patient with breast cancer. The T2 values of phosphocreatine, phosphodiesters (PDE) and inorganic phosphate in calf muscle were 193 ± 5 ms, 375 ± 44 ms and 96 ± 10 ms, respectively, and the apparent T2 value of γ‐ATP was 25 ± 6 ms. A T2 value of 136 ± 15 ms for inorganic phosphate was measured in glandular breast tissue of a healthy volunteer. The T2 values of phosphomonoesters (PME) and PDE in breast cancer tissue (ductulolobular carcinoma) ranged between 170 and 210 ms, and the PME to PDE ratios were calculated to be phosphoethanolamine/glycerophosphoethanolamine = 2.7, phosphocholine/glycerophosphocholine = 1.8 and PME/PDE = 2.3. Considering the relatively short T2* values of the metabolites in breast tissue at 7 T, the echo spacing can be short without compromising spectral resolution, whilst maximizing the sensitivity. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
10.
Cao MD Döpkens M Krishnamachary B Vesuna F Gadiya MM Lønning PE Bhujwalla ZM Gribbestad IS Glunde K 《NMR in biomedicine》2012,25(9):1033-1042
11.
Wybe J.M. van der Kemp Bertine L. Stehouwer Vincent O. Boer Peter R. Luijten Dennis W.J. Klomp Jannie P. Wijnen 《NMR in biomedicine》2017,30(2)
In vivo water‐ and fat‐suppressed 1H magnetic resonance spectroscopy (MRS) and 31P magnetic resonance adiabatic multi‐echo spectroscopic imaging were performed at 7 T in duplicate in healthy fibroglandular breast tissue of a group of eight volunteers. The transverse relaxation times of 31P metabolites were determined, and the reproducibility of 1H and 31P MRS was investigated. The transverse relaxation times for phosphoethanolamine (PE) and phosphocholine (PC) were fitted bi‐exponentially, with an added short T2 component of 20 ms for adenosine monophosphate, resulting in values of 199 ± 8 and 239 ± 14 ms, respectively. The transverse relaxation time for glycerophosphocholine (GPC) was also fitted bi‐exponentially, with an added short T2 component of 20 ms for glycerophosphatidylethanolamine, which resonates at a similar frequency, resulting in a value of 177 ± 6 ms. Transverse relaxation times for inorganic phosphate, γ‐ATP and glycerophosphatidylcholine mobile phospholipid were fitted mono‐exponentially, resulting in values of 180 ± 4, 19 ± 3 and 20 ± 4 ms, respectively. Coefficients of variation for the duplicate determinations of 1H total choline (tChol) and the 31P metabolites were calculated for the group of volunteers. The reproducibility of inorganic phosphate, the sum of phosphomonoesters and the sum of phosphodiesters with 31P MRS imaging was superior to the reproducibility of 1H MRS for tChol. 1H and 31P data were combined to calculate estimates of the absolute concentrations of PC, GPC and PE in healthy fibroglandular tissue, resulting in upper limits of 0.1, 0.1 and 0.2 mmol/kg of tissue, respectively. 相似文献
12.
Haddadin IS McIntosh A Meisamy S Corum C Styczynski Snyder AL Powell NJ Nelson MT Yee D Garwood M Bolan PJ 《NMR in biomedicine》2009,22(1):65-76
In vivo 1H MRS is rapidly developing as a clinical tool for diagnosing and characterizing breast cancers. Many in vivo and in vitro experiments have demonstrated that alterations in concentrations of choline-containing metabolites are associated with malignant transformation. In recent years, considerable efforts have been made to evaluate the role of 1H MRS measurements of total choline-containing compounds in the management of patients with breast cancer. Current technological developments, including the use of high-field MR scanners and quantitative spectroscopic analysis methods, promise to increase the sensitivity and accuracy of breast MRS. This article reviews the literature describing in vivo MRS in breast cancer, with an emphasis on the development of high-field MR scanning and quantitative methods. Potential applications of these technologies for diagnosing suspicious lesions and monitoring response to chemotherapy are discussed. 相似文献
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14.
Darpolor MM Kennealey PT Le HC Zakian KL Ackerstaff E Rizwan A Chen JH Sambol EB Schwartz GK Singer S Koutcher JA 《NMR in biomedicine》2011,24(9):1159-1168
The topoisomerase I inhibitor, irinotecan, and its active metabolite SN‐38 have been shown to induce G2/M cell cycle arrest without significant cell death in human colon carcinoma cells (HCT‐116). Subsequent treatment of these G2/M‐arrested cells with the cyclin‐dependent kinase inhibitor, flavopiridol, induced these cells to undergo apoptosis. The goal of this study was to develop a noninvasive metabolic biomarker for early tumor response and target inhibition of irinotecan followed by flavopiridol treatment in a longitudinal study. A total of eleven mice bearing HCT‐116 xenografts were separated into two cohorts where one cohort was administered saline and the other treated with a sequential course of irinotecan followed by flavopiridol. Each mouse xenograft was longitudinally monitored with proton (1H)‐decoupled phosphorus (31P) magnetic resonance spectroscopy (MRS) before and after treatment. A statistically significant decrease in phosphocholine (p = 0.0004) and inorganic phosphate (p = 0.0103) levels were observed in HCT‐116 xenografts following treatment, which were evidenced within twenty‐four hours of treatment completion. Also, a significant growth delay was found in treated xenografts. To discern the underlying mechanism for the treatment response of the xenografts, in vitro HCT‐116 cell cultures were investigated with enzymatic assays, cell cycle analysis, and apoptotic assays. Flavopiridol had a direct effect on choline kinase as measured by a 67% reduction in the phosphorylation of choline to phosphocholine. Cells treated with SN‐38 alone underwent 83 ± 5% G2/M cell cycle arrest compared to untreated cells. In cells, flavopiridol alone induced 5 ± 1% apoptosis while the sequential treatment (SN‐38 then flavopiridol) resulted in 39 ± 10% apoptosis. In vivo 1H‐decoupled 31P MRS indirectly measures choline kinase activity. The decrease in phosphocholine may be a potential indicator of early tumor response to the sequential treatment of irinotecan followed by flavopiridol in noninvasive and/or longitudinal studies. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
15.
31P‐MRS of healthy human brain: ATP synthesis,metabolite concentrations,pH, and T1 relaxation times
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The conventional method for measuring brain ATP synthesis is 31P saturation transfer (ST), a technique typically dependent on prolonged pre‐saturation with γ‐ATP. In this study, ATP synthesis rate in resting human brain is evaluated using EBIT (exchange kinetics by band inversion transfer), a technique based on slow recovery of γ‐ATP magnetization in the absence of B1 field following co‐inversion of PCr and ATP resonances with a short adiabatic pulse. The unidirectional rate constant for the Pi → γ‐ATP reaction is 0.21 ± 0.04 s?1 and the ATP synthesis rate is 9.9 ± 2.1 mmol min?1 kg?1 in human brain (n = 12 subjects), consistent with the results by ST. Therefore, EBIT could be a useful alternative to ST in studying brain energy metabolism in normal physiology and under pathological conditions. In addition to ATP synthesis, all detectable 31P signals are analyzed to determine the brain concentration of phosphorus metabolites, including UDPG at around 10 ppm, a previously reported resonance in liver tissues and now confirmed in human brain. Inversion recovery measurements indicate that UDPG, like its diphosphate analogue NAD, has apparent T1 shorter than that of monophosphates (Pi, PMEs, and PDEs) but longer than that of triphosphate ATP, highlighting the significance of the 31P–31P dipolar mechanism in T1 relaxation of polyphosphates. Another interesting finding is the observation of approximately 40% shorter T1 for intracellular Pi relative to extracellular Pi, attributed to the modulation by the intracellular phosphoryl exchange reaction Pi ? γ‐ATP. The sufficiently separated intra‐ and extracellular Pi signals also permit the distinction of pH between intra‐ and extracellular environments (pH 7.0 versus pH 7.4). In summary, quantitative 31P MRS in combination with ATP synthesis, pH, and T1 relaxation measurements may offer a promising tool to detect biochemical alterations at early stages of brain dysfunctions and diseases. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
Marek Chmelik Michal Považan Martin Krššák Stephan Gruber Martin Tkačov Siegfried Trattnig Wolfgang Bogner 《NMR in biomedicine》2014,27(4):478-485
Phosphorus (31P) MRS is a powerful tool for the non‐invasive investigation of human liver metabolism. Four in vivo 31P localization approaches (single voxel image selected in vivo spectroscopy (3D‐ISIS), slab selective 1D‐ISIS, 2D chemical shift imaging (CSI), and 3D‐CSI) with different voxel volumes and acquisition times were demonstrated in nine healthy volunteers. Localization techniques provided comparable signal‐to‐noise ratios normalized for voxel volume and acquisition time differences, Cramer–Rao lower bounds (8.7 ± 3.3%1D‐ISIS, 7.6 ± 2.5%3D‐ISIS, 8.6 ± 4.2%2D‐CSI, 10.3 ± 2.7%3D‐CSI), and linewidths (50 ± 24 Hz1D‐ISIS, 34 ± 10 Hz3D‐ISIS, 33 ± 10 Hz2D‐CSI, 34 ± 11 Hz3D‐CSI). Longitudinal (T1) relaxation times of human liver metabolites at 7 T were assessed by 1D‐ISIS inversion recovery in the same volunteers (n = 9). T1 relaxation times of hepatic 31P metabolites at 7 T were the following: phosphorylethanolamine – 4.41 ± 1.55 s; phosphorylcholine – 3.74 ± 1.31 s; inorganic phosphate – 0.70 ± 0.33 s; glycerol 3‐phosphorylethanolamine – 6.19 ± 0.91 s; glycerol 3‐phosphorylcholine – 5.94 ± 0.73 s; γ‐adenosine triphosphate (ATP) – 0.50 ± 0.08 s; α‐ATP – 0.46 ± 0.07 s; β‐ATP – 0.56 ± 0.07 s. The improved spectral resolution at 7 T enabled separation of resonances in the phosphomonoester and phosphodiester spectral region as well as nicotinamide adenine dinucleotide and uridine diphosphoglucose signals. An additional resonance at 2.06 ppm previously assigned to phosphoenolpyruvate or phosphatidylcholine is also detectable. These are the first 31P metabolite relaxation time measurements at 7 T in human liver, and they will help in the exploration of new, exciting questions in metabolic research with 7 T MR. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
17.
31P MRS offers a unique view of muscle metabolism in vivo, but correct quantification is important. Inter-study correlation of estimates of [Pi] and [phosphocreatine (PCr)] in a number of published studies suggest that the main technical problem in calibrated 31P MRS studies is the measurement of PCr and Pi signal intensities, rather than absolute quantification of [ATP]. For comparison, we discuss the few published biopsy studies of calf muscle and a selection of the many studies of quadriceps muscle. The ATP concentration is close to the value that we obtained in calf muscle in our own study, presented here, on four healthy subjects, by localised 31P MRS using a surface coil incorporating an internal reference and calibrated using an external phantom. However, the freeze-clamp biopsy PCr concentration is approximately 20% lower than the value obtained by 31P MRS, consistent with PCr breakdown by creatine kinase during freezing. Finally, we illustrate some consequences of uncertainty in resting [PCr] for analysis of mitochondrial function from PCr kinetics using a published 31P MRS study of exercise and recovery: the lower the assumed resting [PCr], the lower the absolute rate of oxidative ATP synthesis estimated from the PCr resynthesis rate; in addition, the lower the assumed resting [PCr], or the higher the assumed [total creatine], the higher the apparent resting [ADP], and therefore the more sigmoid the relationship between the rate of oxidative ATP synthesis and [ADP]. Correct quantification of resting metabolite concentrations is crucially important for this sort of analysis. Our own results ([PCr] = 33 +/- 2 mM, [Pi] = 4.5 +/- 0.2 mM, and [ATP] = 8.2 +/- 0.4 mM; mean +/- SEM) are close to the overall mean values of the 10 published studies on calf muscle by 'calibrated' 31P MRS (as in the present work), and of [PCr] and [Pi] in a representative selection of 'uncalibrated' 31P MRS studies (i.e. from measured PCr/ATP and Pi/ATP ratios, assuming a literature value for [ATP]). 相似文献
18.
Erwin Krikken Wybe J.M. van der Kemp Paul J. van Diest Thijs van Dalen Hanneke W.M. van Laarhoven Peter R. Luijten Dennis W.J. Klomp Jannie P. Wijnen 《NMR in biomedicine》2019,32(6)
The purpose of this work was to investigate whether noninvasive early detection (after the first cycle) of response to neoadjuvant chemotherapy (NAC) in breast cancer patients was possible. 31P‐MRSI at 7 T was used to determine different phosphor metabolites ratios and correlate this to pathological response. 31P‐MRSI was performed in 12 breast cancer patients treated with NAC. 31P spectra were fitted and aligned to the frequency of phosphoethanolamine (PE). Metabolic signal ratios for phosphomonoesters/phosphodiesters (PME/PDE), phosphocholine/glycerophosphatidylcholine (PC/GPtC), phosphoethanolamine/glycerophosphoethanolamine (PE/GPE) and phosphomonoesters/in‐organic phosphate (PME/Pi) were determined from spectral fitting of the individual spectra and the summed spectra before and after the first cycle of NAC. Metabolic ratios were subsequently related to pathological response. Additionally, the correlation between the measured metabolic ratios and Ki‐67 levels was determined using linear regression. Four patients had a pathological complete response after treatment, five patients a partial pathological response, and three patients did not respond to NAC. In the summed spectrum after the first cycle of NAC, PME/Pi and PME/PDE decreased by 18 and 13%, respectively. A subtle difference among the different response groups was observed in PME/PDE, where the nonresponders showed an increase and the partial and complete responders a decrease (P = 0.32). No significant changes in metabolic ratios were found. However, a significant association between PE/Pi and the Ki‐67 index was found (P = 0.03). We demonstrated that it is possible to detect subtle changes in 31P metabolites with a 7 T MR system after the first cycle of NAC treatment in breast cancer patients. Nonresponders showed different changes in metabolic ratios compared with partial and complete responders, in particular for PME/PDE; however, more patients need to be included to investigate its clinical value. 相似文献
19.
In vivo 31P MRS assessment of intracellular NAD metabolites and NAD+/NADH redox state in human brain at 4 T
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NAD+ and NADH play key roles in cellular respiration. Intracellular redox state defined by the NAD+/NADH ratio (RX) reflects the cellular metabolic and physiopathological status. By taking advantage of high/ultrahigh magnetic field strengths, we have recently established a novel in vivo 31P MRS‐based NAD assay for noninvasive and quantitative measurements of intracellular NAD concentrations and redox state in animal and human brains at 16.4 T, 9.4 T and 7 T. To explore its potential for clinical application, in this study we investigated the feasibility of assessing the NAD metabolism and redox state in human brain at a lower field of 4 T by incorporating the 1H‐decoupling technique with the in vivo 31P NAD assay. The use of 1H decoupling significantly narrowed the linewidths of NAD and α‐ATP resonances, resulting in higher sensitivity and better spectral resolution as compared with the 1H‐coupled 31P spectrum. These improvements made it possible to reliably quantify cerebral NAD concentrations and RX, consistent with previously reported results obtained from similar age human subjects at 7 T. In summary, this work demonstrates the capability and utility of the 1H‐decoupled 31P MRS‐based NAD assay at lower field strength; thus, it opens new opportunities for studying intracellular NAD metabolism and redox state in human brain at clinical settings. This conclusion is supported by the simulation results, indicating that similar performance and reliability as observed at 4T can be achieved at 3 T with the same signal‐to‐noise ratio. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
20.
Kan HE Klomp DW Wong CS Boer VO Webb AG Luijten PR Jeneson JA 《NMR in biomedicine》2010,23(8):995-1000
Non‐invasive determination of mitochondrial content is an important objective in clinical and sports medicine. 31P MRS approaches to obtain information on this parameter at low field strength typically require in‐magnet exercise. Direct observation of the intra‐mitochondrial inorganic phosphate (Pi) pool in resting muscle would constitute an alternative, simpler method. In this study, we exploited the higher spectral resolution and signal‐to‐noise at 7T to investigate the MR visibility of this metabolite pool. 31P in vivo MR spectra of the resting soleus (SOL) muscle were obtained with 1H MR image‐guided surface coil localization (six volunteers) and of the SOL and tibialis anterior (TA) muscle using 2D CSI (five volunteers). A resonance at a frequency 0.38 ppm downfield from the cytosolic Pi resonance (Pi1; pH 7.0 ± 0.04) was reproducibly detected in the SOL muscle in all subjects and conditionally attributed to the intra‐mitochondrial Pi pool (Pi2; pH 7.3 ± 0.07). In the SOL muscle, the Pi2/Pi1 ratio was 1.6 times higher compared to the TA muscle in the same individual. Localized 3D CSI results showed that the Pi2 peak was present in voxels well away from blood vessels. Determination of the T1 of the two Pi pools in a single individual using adiabatic excitation of the spectral region around 5 ppm yielded estimates of 4.3 ± 0.4 s vs 1.4 ± 0.5 s for Pi1 and Pi2, respectively. Together, these results suggest that the intra‐mitochondrial Pi pool in resting human skeletal muscle may be visible with 31P MRS at high field. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献