Loreen Ruhm
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View article: Joint learning of nonlinear representation and projection for fast constrained MRSI reconstruction
Joint learning of nonlinear representation and projection for fast constrained MRSI reconstruction Open
Purpose To develop and evaluate a novel method for computationally efficient reconstruction from noisy MR spectroscopic imaging (MRSI) data. Methods The proposed method features (a) a novel strategy that jointly learns a nonlinear low‐dime…
View article: Joint Learning of Nonlinear Representation and Projection for Fast Constrained MRSI Reconstruction
Joint Learning of Nonlinear Representation and Projection for Fast Constrained MRSI Reconstruction Open
Learning and utilizing low-dimensional representations for high-dimensional imaging problems is an active research area. We present here a novel method for computationally efficient reconstruction from noisy MR spectroscopic imaging (MRSI)…
View article: LeaRning nonlineAr representatIon and projectIon for faSt constrained MRSI rEconstruction (RAIISE)
LeaRning nonlineAr representatIon and projectIon for faSt constrained MRSI rEconstruction (RAIISE) Open
Learning and utilizing low-dimensional models for high-dimensional spatiospectral imaging problems is an active research area. We present here a novel method for computationally efficient reconstruction from noisy high-dimensional MR spect…
View article: Joint Learning of Nonlinear Representation and Projection for Fast Constrained MRSI Reconstruction
Joint Learning of Nonlinear Representation and Projection for Fast Constrained MRSI Reconstruction Open
Learning and utilizing low-dimensional representations for high-dimensional imaging problems is an active research area. We present here a novel method for computationally efficient reconstruction from noisy MR spectroscopic imaging (MRSI)…
View article: Mapping of glutamate metabolism using 1H FID-MRSI after oral administration of [1-13C]Glc at 9.4 T
Mapping of glutamate metabolism using 1H FID-MRSI after oral administration of [1-13C]Glc at 9.4 T Open
Glutamate is the major excitatory transmitter in the brain and malfunction of the related metabolism is associated with various neurological diseases and disorders. The observation of labeling changes in the spectra after the administratio…
View article: Improving the Effective Spatial Resolution in 1H-MRSI of the Prostate with Three-Dimensional Overdiscretized Reconstructions
Improving the Effective Spatial Resolution in 1H-MRSI of the Prostate with Three-Dimensional Overdiscretized Reconstructions Open
In in vivo 1H-MRSI of the prostate, small matrix sizes can cause voxel bleeding extending to regions far from a voxel, dispersing a signal of interest outside that voxel and mixing extra-prostatic residual lipid signals into the prostate. …
View article: Mapping of Glutamate Metabolism using 1H FID-MRSI after oral Administration of [1-<sup>13</sup>C]Glc at 9.4 T
Mapping of Glutamate Metabolism using 1H FID-MRSI after oral Administration of [1-<sup>13</sup>C]Glc at 9.4 T Open
Glutamate is the major excitatory transmitter in the brain and malfunction of the related metabolism is associated with various neurological diseases and disorders. The observation of labeling changes in the spectra after the administratio…
View article: Deuterium metabolic imaging of the human brain in vivo at 7 T
Deuterium metabolic imaging of the human brain in vivo at 7 T Open
Purpose To explore the potential of deuterium metabolic imaging (DMI) in the human brain in vivo at 7 T, using a multi‐element deuterium ( 2 H) RF coil for 3D volume coverage. Methods 1 H‐MR images and localized 2 H MR spectra were acquire…
View article: A 32‐element loop/dipole hybrid array for human head imaging at <scp>7 T</scp>
A 32‐element loop/dipole hybrid array for human head imaging at <span>7 T</span> Open
Purpose To improve whole‐brain SNR at 7 Tesla, a novel 32‐element hybrid human head array coil was developed, constructed, and tested. Methods Our general design strategy is based on 2 major ideas: Firstly, following suggestions of previou…
View article: Measurement of glucose metabolism in the occipital lobe and frontal cortex after oral administration of [1-13C]glucose at 9.4 T
Measurement of glucose metabolism in the occipital lobe and frontal cortex after oral administration of [1-13C]glucose at 9.4 T Open
For the first time, labeling effects after oral intake of [1-13C]glucose are observed in the human brain with pure 1H detection at 9.4 T. Spectral time series were acquired using a short-TE 1H MRS MC-semiLASER (Metabolite Cycling semi Loca…
View article: Phosphorus transversal relaxation times and metabolite concentrations in the human brain at 9.4 T
Phosphorus transversal relaxation times and metabolite concentrations in the human brain at 9.4 T Open
A method to estimate phosphorus ( 31 P) transversal relaxation times (T 2 s) of coupled spin systems is demonstrated. Additionally, intracellular and extracellular pH and relaxation‐corrected metabolite concentrations are reported. Echo ti…
View article: Double‐row dipole/loop combined array for human whole brain imaging at 7 T
Double‐row dipole/loop combined array for human whole brain imaging at 7 T Open
Important issues in designing radiofrequency (RF) coils for human head imaging at ultra‐high field (UHF; ≥7 T) are the inhomogeneity and longitudinal coverage (along the magnet axis) of the transmit (Tx) RF field. Both the homogeneity and …
View article: Dynamic observation of<sup>2</sup>H labeled compounds in the human brain with<sup>1</sup>H versus<sup>2</sup>H magnetic resonance spectroscopy at 9.4T
Dynamic observation of<sup>2</sup>H labeled compounds in the human brain with<sup>1</sup>H versus<sup>2</sup>H magnetic resonance spectroscopy at 9.4T Open
The metabolic pathway of [6,6’- 2 H 2 ]-labeled glucose was investigated with two different techniques. The first technique used direct detection of deuterium applying Deuterium Metabolic Imaging (DMI). The second technique used the indire…
View article: <sup>31</sup>P Transversal Relaxation Times and Metabolite Concentrations in the Human Brain at 9.4T
<sup>31</sup>P Transversal Relaxation Times and Metabolite Concentrations in the Human Brain at 9.4T Open
A method to estimate phosphorus ( 31 P) transversal relaxation times (T 2 ) of coupled spin systems is demonstrated. Additionally, intracellular and extracellular pH (pH ext , pH int ) and relaxation corrected metabolite concentrations are…
View article: Deuterium metabolic imaging in the human brain at 9.4 Tesla with high spatial and temporal resolution
Deuterium metabolic imaging in the human brain at 9.4 Tesla with high spatial and temporal resolution Open
View article: 3D <sup>31</sup>P MRSI of the human brain at 9.4 Tesla: Optimization and quantitative analysis of metabolic images
3D <sup>31</sup>P MRSI of the human brain at 9.4 Tesla: Optimization and quantitative analysis of metabolic images Open
Purpose To present 31 P whole brain MRSI with a high spatial resolution to probe quantitative tissue analysis of 31 P MRSI at an ultrahigh field strength of 9.4 Tesla. Methods The study protocol included a 31 P MRSI measurement with an eff…
View article: 9.4 T double‐tuned <sup>13</sup>C/<sup>1</sup>H human head array using a combination of surface loops and dipole antennas
9.4 T double‐tuned <sup>13</sup>C/<sup>1</sup>H human head array using a combination of surface loops and dipole antennas Open
MRI at ultra‐high field (UHF, ≥7 T) provides a natural strategy for improving the quality of X‐nucleus magnetic resonance spectroscopy and imaging due to the intrinsic benefit of increased signal‐to‐noise ratio. Considering that RF coils r…
View article: Feasibility of deuterium magnetic resonance spectroscopy of 3-O-Methylglucose at 7 Tesla
Feasibility of deuterium magnetic resonance spectroscopy of 3-O-Methylglucose at 7 Tesla Open
Deuterium Magnetic Resonance Spectroscopy (DMRS) is a non-invasive technique that allows the detection of deuterated compounds in vivo. DMRS has a large potential to analyze uptake, perfusion, washout or metabolism, since deuterium is a st…
View article: Folded‐end dipole transceiver array for human whole‐brain imaging at 7 T
Folded‐end dipole transceiver array for human whole‐brain imaging at 7 T Open
The advancement of clinical applications of ultrahigh field (UHF) MRI depends heavily on advances in technology, including the development of new radiofrequency (RF) coil designs. Currently, the number of commercially available 7 T head RF…
View article: Unshielded bent folded‐end dipole 9.4 T human head transceiver array decoupled using modified passive dipoles
Unshielded bent folded‐end dipole 9.4 T human head transceiver array decoupled using modified passive dipoles Open
Purpose To develop an unshielded dipole transceiver array for human head imaging at 9.4 Tesla and to improve decoupling of adjacent dipole elements, a novel array design with modified passive dipole antennas was developed, evaluated, and t…
View article: Comparison of four 31P single‐voxel MRS sequences in the human brain at 9.4 T
Comparison of four 31P single‐voxel MRS sequences in the human brain at 9.4 T Open
Purpose In this study, different single‐voxel localization sequences were implemented and systematically compared for the first time for phosphorous MRS ( 31 P‐MRS) in the human brain at 9.4 T. Methods Two multishot sequences, image‐select…
View article: Bent folded‐end dipole head array for ultrahigh‐field MRI turns “dielectric resonance” from an enemy to a friend
Bent folded‐end dipole head array for ultrahigh‐field MRI turns “dielectric resonance” from an enemy to a friend Open
Purpose To provide transmit whole‐brain coverage at 9.4 T using an array with only eight elements and improve the specific absorption rate (SAR) performance, a novel dipole array was developed, constructed, and tested. Methods The array co…
View article: Decoupling of folded‐end dipole antenna elements of a 9.4 T human head array using an RF shield
Decoupling of folded‐end dipole antenna elements of a 9.4 T human head array using an RF shield Open
Dipole antennas have recently been introduced to the field of MRI and successfully used, mostly as elements of ultra‐high field (UHF, ≥ 7 T) human body arrays. Usage of dipole antennas for UHF human head transmit (Tx) arrays is still under…
View article: Double‐tuned <sup>31</sup>P/<sup>1</sup>H human head array with high performance at both frequencies for spectroscopic imaging at 9.4T
Double‐tuned <sup>31</sup>P/<sup>1</sup>H human head array with high performance at both frequencies for spectroscopic imaging at 9.4T Open
Purpose To develop a robust design of a human head double‐tuned 31 P/ 1 H array, which provides good performance at both 31 P and 1 H frequencies for MR spectroscopic imaging at 9.4T. Methods Increasing the number of surface loops in a hum…