Relative identifiability of anisotropic properties from magnetic resonance elastography
NMR in Biomedicine, EarlyView. (Source: NMR in Biomedicine)
Source: NMR in Biomedicine - November 6, 2017 Category: Radiology Source Type: research
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NMR in Biomedicine, Ahead of Print. (Source: NMR in Biomedicine)
Source: NMR in Biomedicine - November 6, 2017 Category: Radiology Source Type: research
Probing the cardiac malate –aspartate shuttle non‐invasively using hyperpolarized [1,2‐13C2]pyruvate
In this study, we investigated the mechanism driving the observed changes to hyperpolarized [2‐13C]pyruvate metabolism. Using hyperpolarized [1,2‐13C]pyruvate with magnetic resonance spectroscopy (MRS) in the porcine heart with different workloads, it was possible to probe 13C–glutamate labeling relative to rates of cytosolic metabolism, PDH flux and TCA cycle turnover in a single experiment non‐invasively. Via the [1‐13C]pyruvate label, we observed more than a five‐fold increase in the cytosolic conversion of pyruvate to [1‐13C]lactate and [1‐13C]alanine with higher workload. 13C–Bicarbonate production b...
Source: NMR in Biomedicine - November 6, 2017 Category: Radiology Authors: Albert P. Chen, Angus Z. Lau, Yi ‐ping Gu, Marie A. Schroeder, Jennifer Barry, Charles H. Cunningham Tags: RESEARCH ARTICLE Source Type: research
Differentiating the histologic grades of gliomas preoperatively using amide proton transfer ‐weighted (APTW) and intravoxel incoherent motion MRI
In conclusion, APTW and IVIM, as two promising supplementary sequences for routine MRI, could be valuable in differentiating LGGs from HGGs.
Amide proton transfer‐weighted (APTW) imaging can generate image contrast mainly related to endogenous cellular proteins in tissue, and intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) can separate water molecular diffusion from microcirculation. Fifty‐one patients with glioma were recruited to investigate the diagnostic performance of APT and IVIM MRI. Our results show that these supplementary MRI methods are valuable in differentiating low‐ from high‐gra...
Source: NMR in Biomedicine - November 3, 2017 Category: Radiology Authors: Tianyu Zou, Hao Yu, Chunxiu Jiang, Xianlong Wang, Shanshan Jiang, Qihong Rui, Yingjie Mei, Jinyuan Zhou, Zhibo Wen Tags: RESEARCH ARTICLE Source Type: research
Is there evidence for more than two diffusion components in abdominal organs? – A magnetic resonance imaging study in healthy volunteers
In this study, we assessed the ground truth of underlying diffusion components in healthy abdominal organs using an extensive DWI protocol and subsequent computation of apparent diffusion coefficient ‘spectra’, similar to the computation of previously described T2 relaxation spectra. Diffusion datasets of eight healthy subjects were acquired in a 3‐T magnetic resonance scanner using 68 different b values during free breathing (equidistantly placed in the range 0–1005 s/mm2). Signal intensity curves as a function of the b value were analyzed in liver, spleen and kidneys using non‐negative least‐squares fitting t...
Source: NMR in Biomedicine - November 3, 2017 Category: Radiology Authors: Moritz C. Wurnig, Manon Germann, Andreas Boss Tags: RESEARCH ARTICLE Source Type: research
Improved resolution of glutamate, glutamine and γ‐aminobutyric acid with optimized point‐resolved spectroscopy sequence timings for their simultaneous quantification at 9.4 T
Glutamine (Gln), glutamate (Glu) and γ‐aminobutyric acid (GABA) are relevant brain metabolites that can be measured with magnetic resonance spectroscopy (MRS). This work optimizes the point‐resolved spectroscopy (PRESS) sequence echo times, TE1 and TE2, for improved simultaneous quantification of the three metabolites at 9.4 T. Quantification was based on the proton resonances of Gln, Glu and GABA at ≈2.45, ≈2.35 and ≈2.28 ppm, respectively. Glu exhibits overlap with both Gln and GABA; in addition, the Gln peak is contaminated by signal from the strongly coupled protons of N‐acetylaspartate (NAA), which resona...
Source: NMR in Biomedicine - November 3, 2017 Category: Radiology Authors: Brennen J. Dobberthien, Anthony G. Tessier, Atiyah Yahya Tags: RESEARCH ARTICLE Source Type: research
1H NMRS of carnosine combined with 31P NMRS to better characterize skeletal muscle pH dysregulation in Duchenne muscular dystrophy
In recent years, quantitative nuclear magnetic resonance imaging and spectroscopy (NMRI and NMRS) have been used more systematically as outcome measures in natural history and clinical trial studies for Duchenne muscular dystrophy (DMD). Whereas most of these studies have emphasized the evaluation of the fat fraction as an assessment for disease severity, less focus has been placed on metabolic indices measured by NMRS. 31P NMRS in DMD reveals an alkaline inorganic phosphate (Pi) pool, originating from either leaky dystrophic myocytes or an increased interstitial space. 1H NMRS, exploiting the pH‐sensitive proton resonan...
Source: NMR in Biomedicine - November 1, 2017 Category: Radiology Authors: Harmen Reyngoudt, Suna Turk, Pierre G. Carlier Tags: RESEARCH ARTICLE Source Type: research
Relative identifiability of anisotropic properties from magnetic resonance elastography
In conclusion, Young's modulii, shear modulii and damping can theoretically be well determined from MRE data, but Poisson's ratio is not as well determined and could be set to a reasonable value for biological tissue (close to 0.5).
Parameters that describe a transversely isotropic material are not equally identifiable from MRE displacement fields. This is shown using a finite‐element model update method, based on minimizing the differences between simulated and measured displacements, with simulated and experimental phantom MRE displacements. Identifiability was compared using quantitative measures calculated from the ...
Source: NMR in Biomedicine - November 1, 2017 Category: Radiology Authors: Renee Miller, Arunark Kolipaka, Martyn P. Nash, Alistair A. Young Tags: SPECIAL ISSUE RESEARCH ARTICLE Source Type: research
In vivo detection and automatic analysis of GABA in the mouse brain with MEGA ‐PRESS at 9.4 T
The goals of this study were to develop an acquisition protocol and the analysis tools for Meshcher–Garwood point‐resolved spectroscopy (MEGA‐PRESS) in mouse brain at 9.4 T, to allow the in vivo detection of γ‐aminobutyric acid (GABA) and to examine whether isoflurane alters GABA levels in the thalamus during anesthesia. We implemented the MEGA‐PRESS sequence on a Bruker 94/20 system with ParaVision 6.0.1, and magnetic resonance spectra were acquired from nine male wild‐type C57BL/6 J mice at the thalamus. Four individual scans were obtained for each mouse in a 2‐h time course whilst the mouse was anesthet...
Source: NMR in Biomedicine - November 1, 2017 Category: Radiology Authors: Jia Guo, Zhu Gang, Yanping Sun, Andrew Laine, Scott A. Small, Douglas L. Rothman Tags: RESEARCH ARTICLE Source Type: research
Radiomics in paediatric neuro ‐oncology: A multicentre study on MRI texture analysis
Brain tumours are the most common solid cancers in children in the UK and are the most common cause of cancer deaths in this age group. Despite current advances in MRI, non‐invasive diagnosis of paediatric brain tumours has yet to find its way into routine clinical practice. Radiomics, the high‐throughput extraction and analysis of quantitative image features (e.g. texture), offers potential solutions for tumour characterization and decision support.
In the search for diagnostic oncological markers, the primary aim of this work was to study the application of MRI texture analysis (TA) for the classification of paediatr...
Source: NMR in Biomedicine - October 27, 2017 Category: Radiology Authors: Ahmed E. Fetit, Jan Novak, Daniel Rodriguez, Dorothee P. Auer, Christopher A. Clark, Richard G. Grundy, Andrew C. Peet, Theodoros N. Arvanitis Tags: RESEARCH ARTICLE Source Type: research
Erratum
(Source: NMR in Biomedicine)
Source: NMR in Biomedicine - October 26, 2017 Category: Radiology Tags: ERRATUM Source Type: research
Hadamard editing of glutathione and macromolecule ‐suppressed GABA
In this study, a method for simultaneous J‐difference spectral‐edited magnetic resonance spectroscopy (MRS) of GSH and GABA with suppression of macromolecular (MM) signals at 3 T is proposed. MM‐suppressed Hadamard encoding and reconstruction of MEGA (Mescher–Garwood)‐edited spectroscopy (HERMES) consists of four sub‐experiments (TE = 80 ms), with 20‐ms editing pulses applied at: (A) 4.56 and 1.9 ppm; (B) 4.56 and 1.5 ppm; (C) 1.9 ppm; and (D) 1.5 ppm. One Hadamard combination (A + B – C – D) yields GSH‐edited spectra, and another (A – B + C – D) yields GABA‐edited spectra, with symmetric suppress...
Source: NMR in Biomedicine - October 26, 2017 Category: Radiology Authors: Georg Oeltzschner, Kimberly L. Chan, Muhammad G. Saleh, Mark Mikkelsen, Nicolaas A. Puts, Richard A. E. Edden Tags: RESEARCH ARTICLE Source Type: research
Value of whole breast magnetic resonance elastography added to MRI for lesion characterization
The purpose of this work was to assess the diagnostic value of magnetic resonance elastography (MRE) in addition to MRI to differentiate malignant from benign breast tumors, and the feasibility of performing MRE on the whole breast.
MRE quantified biomechanical properties within the entire breast (50 slices) using an 11 min acquisition protocol at an isotropic image acquisition resolution of 2 × 2 × 2 mm3. Fifty patients were included. Finally, 43 patients (median age 52) with a suspect breast lesion detected by mammography and/or ultrasound were examined by MRI and MRE at 1.5 T. The viscoelastic parameters, i.e. ...
Source: NMR in Biomedicine - October 26, 2017 Category: Radiology Authors: Corinne Balleyguier, Aicha Ben Lakhdar, Ariane Dunant, Marie ‐Christine Mathieu, Suzette Delaloge, Ralph Sinkus Tags: RESEARCH ARTICLE Source Type: research
Interleaved 31P MRS imaging of human frontal and occipital lobes using dual RF coils in combination with single ‐channel transmitter–receiver and dynamic B0 shimming
This article presents a simple and effective approach which allows the interleaved measurement of 31P spectra and imaging from two distinct human brain regions of interest with dynamic B0 shimming capability. A transistor–transistor logic controller was employed to actively switch the single‐channel X‐nuclear radiofrequency (RF) transmitter–receiver between two 31P RF surface coils, enabling the interleaved acquisition of two 31P free induction decays (FIDs) from human occipital and frontal lobes within the same repetition time. Linear gradients were incorporated into the RF pulse sequence to perform the first‐or...
Source: NMR in Biomedicine - October 26, 2017 Category: Radiology Authors: Byeong ‐Yeul Lee, Xiao‐Hong Zhu, Myung Kyun Woo, Gregor Adriany, Scott Schillak, Wei Chen Tags: RESEARCH ARTICLE Source Type: research
Density ‐weighted concentric rings k‐space trajectory for 1H magnetic resonance spectroscopic imaging at 7 T
In this study, we propose a new concentric ring trajectory (CRT) for DW‐MRSI that samples k‐space with a density that is proportional to a spatial, isotropic Hanning window. The properties of two different DW‐CRTs were compared against a radially equidistant (RE) CRT and an echo‐planar spectroscopic imaging (EPSI) trajectory in simulations, phantoms and in vivo experiments. These experiments, conducted at 7 T with a fixed nominal voxel size and matched acquisition times, revealed that the two DW‐CRT designs improved the shape of the spatial response function by suppressing side lobes, also resulting in improved s...
Source: NMR in Biomedicine - October 18, 2017 Category: Radiology Authors: Mark Chiew, Wenwen Jiang, Brian Burns, Peder Larson, Adam Steel, Peter Jezzard, M. Albert Thomas, Uzay E. Emir Tags: RESEARCH ARTICLE Source Type: research
