The identification of the phosphodiester (PDE) (31)P MR signals in the healthy human breast at ultra-high field.
In vivo (31)P MRS measurements at 7 T of the PDE signals in the breast were performed ...investigating the chemical shifts, the transverse- and the longitudinal relaxation times. Chemical shifts and transverse relaxation times were compared with non-ambiguous PDE signals from the liver.
The chemical shifts of the PDE signals are shifted -0.5 ppm with respect to glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE), and the transverse and longitudinal relaxation times for these signals are a factor 3 to 4 shorter than expected for aqueous GPC and GPE.
The available experimental evidence suggests that GPC and GPE are not the main source of the PDE signals measured in fibroglandular breast tissue at 7 T. These signals may predominantly originate from mobile phospholipids.
Purpose: The identification of the phosphodiester 31P MR signals in the healthy human breast at ultra-high field.Methods:In vivo 31P MRS measurements at 7 tesla of the phosphodiester signals in the ...breast were performed investigating the chemical shifts, the transverse- and the longitudinal relaxation times. Chemical shifts and transverse relaxation times were compared with non-ambiguous phosphodiester signals from the liver.Results: The chemical shifts of the phosphodiester signals are shifted -0.5 ppm with respect to glycerophosphocholine and -ethanolamine, and the transverse and longitudinal relaxation times for these signals are a factor 3 to 4 shorter than expected for aqueous glycerophosphocholine and -ethanolamine.Conclusions: The available experimental evidence suggests that glycerophosphocholine and –ethanolamine are not the main source of the phosphodiester signals measured in fibroglandular breast tissue at 7 tesla. These signals may predominantly originate from mobile phospholipids.
Purpose: To assess the reproducibility of super(1)H-MR spectroscopic imaging (MRSI) of the human brain at 3T with volume selection by a double spin echo sequence for localization with adiabatic ...refocusing pulses (semi-LASER). Materials and Methods: Twenty volunteers in two different institutions were measured twice with the same pulse sequence at an echo time of 30 msec. Magnetic resonance (MR) spectra were analyzed with LCModel with a simulated basis set including an experimentally acquired macromolecular signal profile. For specific regions in the brain mean metabolite levels, within and between subject variance, and the coefficient of variation (CoV) were calculated (for taurine, glutamate, total N-acetylaspartate, total creatine, total choline, myo-inositol + glycine, and glutamate + glutamine). Results: Repeated measurements showed no significant differences with a paired t-test and a high reproducibility (CoV ranging from 3%-30% throughout the selected volume). Mean metabolite levels and CoV obtained in similar regions in the brain did not differ significantly between two contributing institutions. The major source of differences between different measurements was identified to be the between-subject variations in the volunteers. Conclusion: We conclude that semi-LASER super(1)H-MRSI at 3T is an adequate method to obtain quantitative and reproducible measures of metabolite levels over large parts of the brain, applicable across multiple centers. J. Magn. Reson. Imaging 2010; 31:61-70. copyright 2009 Wiley-Liss, Inc.
Objectives - As a unique tool to assess metabolic fluxes noninvasively, super(13)C magnetic resonance spectroscopy (MRS) could help to characterize and understand malignancy in human tumors. However, ...its low sensitivity has hampered applications in patients. The aim of this study was to demonstrate that with sensitivity-optimized localized super(13)C MRS and intravenous infusion of 1- super(13)Cglucose under euglycemia, it is possible to assess the dynamic conversion of glucose into its metabolic products in vivo in human glioma tissue. Materials and Methods - Measurements were done at 3 T with a broadband single RF channel and a quadrature super(13)C surface coil inserted in a super(1)H volume coil. A super(1)H/ super(13)C polarization transfer sequence was applied, modified for localized acquisition, alternatively in two (50 ml) voxels, one encompassing the tumor and the other normal brain tissue. Results - After about 20 min of 1- super(13)Cglucose infusion, a 3- super(13)Clactate signal appeared among several resonances of metabolic products of glucose in MR spectra of the tumor voxel. The resonance of 3- super(13)Clactate was absent in MR spectra from contralateral tissue. In addition, the intensity of 1- super(13)Cglucose signals in the tumor area was about 50% higher than that in normal tissue, likely reflecting more glucose in extracellular space due to a defective blood-brain barrier. The signal intensity for metabolites produced in or via the tricarboxylic acid (TCA) cycle was lower in the tumor than in the contralateral area, albeit that the ratios of isotopomer signals were comparable. Conclusion - With an improved super(13)C MRS approach, the uptake of glucose and its conversion into metabolites such as lactate can be monitored noninvasively in vivo in human brain tumors. This opens the way to assessing metabolic activity in human tumor tissue.
Abstract Objectives As a unique tool to assess metabolic fluxes noninvasively,13 C magnetic resonance spectroscopy (MRS) could help to characterize and understand malignancy in human tumors. However, ...its low sensitivity has hampered applications in patients. The aim of this study was to demonstrate that with sensitivity-optimized localized13 C MRS and intravenous infusion of 1-13 Cglucose under euglycemia, it is possible to assess the dynamic conversion of glucose into its metabolic products in vivo in human glioma tissue. Materials and Methods Measurements were done at 3 T with a broadband single RF channel and a quadrature13 C surface coil inserted in a1 H volume coil. A1 H/13 C polarization transfer sequence was applied, modified for localized acquisition, alternatively in two (50 ml) voxels, one encompassing the tumor and the other normal brain tissue. Results After about 20 min of 1-13 Cglucose infusion, a 3-13 Clactate signal appeared among several resonances of metabolic products of glucose in MR spectra of the tumor voxel. The resonance of 3-13 Clactate was absent in MR spectra from contralateral tissue. In addition, the intensity of 1-13 Cglucose signals in the tumor area was about 50% higher than that in normal tissue, likely reflecting more glucose in extracellular space due to a defective blood–brain barrier. The signal intensity for metabolites produced in or via the tricarboxylic acid (TCA) cycle was lower in the tumor than in the contralateral area, albeit that the ratios of isotopomer signals were comparable. Conclusion With an improved13 C MRS approach, the uptake of glucose and its conversion into metabolites such as lactate can be monitored noninvasively in vivo in human brain tumors. This opens the way to assessing metabolic activity in human tumor tissue.
Purpose: This work aims to address the limitations faced by researchers in developing and sharing new MRI sequences by implementing an interpreter for the open-source MRI pulse sequence format, ...Pulseq, on a Philips MRI scanner. Methods: The implementation involved modifying a few source code files to create a Pulseq interpreter for the Philips MRI system. Validation experiments were conducted using simulations and phantom scans performed on a 7T Achieva MRI system. The observed sequence and waveforms were compared to the intended ones, and the gradient waveforms produced by the scanner were verified using a field camera. Image reconstruction was performed using the raw k-space samples acquired from both the native vendor environment and the Pulseq interpreter. Results: The reconstructed images obtained through the Pulseq implementation were found to be comparable to those obtained through the native implementation. The performance of the Pulseq interpreter was assessed by profiling the CPU utilization of the MRI spectrometer, showing minimal resource utilization for certain sequences. Conclusion: The successful implementation of the Pulseq interpreter on the Philips MRI scanner demonstrates the feasibility of utilizing Pulseq sequences on Philips MRI scanners. This provides an open-source platform for MRI sequence development, facilitating collaboration among researchers and accelerating scientific progress in the field of MRI.
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