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NMR in Biomedicine

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https://www.readbyqxmd.com/read/27906525/the-clinical-utility-of-qsm-disease-diagnosis-medical-management-and-surgical-planning
#1
REVIEW
Sarah Eskreis-Winkler, Yan Zhang, Jingwei Zhang, Zhe Liu, Alexey Dimov, Ajay Gupta, Yi Wang
Quantitative susceptibility mapping (QSM) is an MR technique that depicts and quantifies magnetic susceptibility sources. Mapping iron, the dominant susceptibility source in the brain, has many important clinical applications. Herein, we review QSM applications in the diagnosis, medical management, and surgical treatment of disease. To assist in early disease diagnosis, QSM can identify elevated iron levels in the motor cortex of amyotrophic lateral sclerosis patients, in the substantia nigra of Parkinson's disease (PD) patients, in the globus pallidus, putamen, and caudate of Huntington's disease patients, and in the basal ganglia of Wilson's disease patients...
December 1, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27898201/diffusion-weighted-imaging-of-the-abdomen-impact-of-b-values-on-texture-analysis-features
#2
Anton S Becker, Matthias W Wagner, Moritz C Wurnig, Andreas Boss
The purpose of this work was to systematically assess the impact of the b-value on texture analysis in MR diffusion-weighted imaging (DWI) of the abdomen. In eight healthy male volunteers, echo-planar DWI sequences at 16 b-values ranging between 0 and 1000 s/mm(2) were acquired at 3 T. Three different apparent diffusion coefficient (ADC) maps were computed (0, 750/100, 390, 750 s/mm(2) /all b-values). Texture analysis of rectangular regions of interest in the liver, kidney, spleen, pancreas, paraspinal muscle and subcutaneous fat was performed on DW images and the ADC maps, applying 19 features computed from the histogram, grey-level co-occurrence matrix (GLCM) and grey-level run-length matrix (GLRLM)...
November 29, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27898185/perfusion-has-no-effect-on-the-in-vivo-cest-effect-from-cr-crcest-in-skeletal-muscle
#3
Feliks Kogan, Randall B Stafford, Erin K Englund, Garry E Gold, Hari Hariharan, John A Detre, Ravinder Reddy
Creatine, a key component of muscle energy metabolism, exhibits a chemical exchange saturation transfer (CEST) effect between its amine group and bulk water, which has been exploited to spatially and temporally map creatine changes in skeletal muscle before and after exercise. In addition, exercise leads to an increase in muscle perfusion. In this work, we determined the effects of perfused blood on the CEST effects from creatine in skeletal muscle. Experiments were performed on healthy human subjects (n = 5) on a whole-body Siemens 7T magnetic resonance imaging (MRI) scanner with a 28-channel radiofrequency (RF) coil...
November 29, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27891691/probing-metabolite-diffusion-at-ultra-short-time-scales-in-the-mouse-brain-using-optimized-oscillating-gradients-and-short-echo-time-diffusion-weighted-mrs
#4
Clémence Ligneul, Julien Valette
Measuring diffusion at ultra-short time scales may yield information about short-range intracellular structure and cytosol viscosity. However, reaching such time scales usually requires oscillating gradients, which in turn imply long echo times TE . Here we propose a new kind of stretched oscillating gradient that allows us to increase diffusion-weighting b while preserving spectral and temporal properties of the gradient modulation. We used these optimized gradients to measure metabolite diffusion in the mouse brain down to effective diffusion times of 1 ms while keeping TE relatively short (60 ms)...
November 28, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27859827/elevated-phosphodiester-and-t2-levels-can-be-measured-in-the-absence-of-fat-infiltration-in-duchenne-muscular-dystrophy-patients
#5
M T Hooijmans, E H Niks, J Burakiewicz, J J G M Verschuuren, A G Webb, H E Kan
Quantitative MRI and MRS are increasingly important as non-invasive outcome measures in therapy development for Duchenne muscular dystrophy (DMD). Many studies have focussed on individual measures such as fat fraction and metabolite levels in relation to age and functionality, but much less attention has been given to how these indices relate to each other. Here, we assessed spatially resolved metabolic changes in leg muscles of DMD patients, and classified muscles according to the degree of fat replacement compared with healthy controls...
November 17, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27862507/accelerated-ferumoxytol-enhanced-4d-multiphase-steady-state-imaging-with-contrast-enhancement-music-cardiovascular-mri-validation-in-pediatric-congenital-heart-disease
#6
Ziwu Zhou, Fei Han, Stanislas Rapacchi, Kim-Lien Nguyen, Daniel Z Brunengraber, Grace-Hyun J Kim, J Paul Finn, Peng Hu
The purpose of this work was to validate a parallel imaging (PI) and compressed sensing (CS) combined reconstruction method for a recently proposed 4D non-breath-held, multiphase, steady-state imaging technique (MUSIC) cardiovascular MRI in a cohort of pediatric congenital heart disease patients. We implemented a graphics processing unit accelerated CS-PI combined reconstruction method and applied it in 13 pediatric patients who underwent cardiovascular MRI after ferumoxytol administration. Conventional breath-held contrast-enhanced magnetic resonance angiography (CE-MRA) was first performed during the first pass of ferumoxytol injection, followed by the original MUSIC and the proposed CS-PI MUSIC during the steady-state distribution phase of ferumoxytol...
November 11, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27862452/effects-of-biological-tissue-structural-anisotropy-and-anisotropy-of-magnetic-susceptibility-on-the-gradient-echo-mri-signal-phase-theoretical-background
#7
Dmitriy A Yablonskiy, Alexander L Sukstanskii
Quantitative susceptibility mapping is a potentially powerful technique for mapping tissue magnetic susceptibility from gradient recalled echo (GRE) MRI signal phase. In this review, we present up-to-date theoretical developments in analyzing the relationships between GRE signal phase and the underlying tissue microstructure and magnetic susceptibility at the cellular level. Two important phenomena contributing to the GRE signal phase are at the focus of this review - tissue structural anisotropy (e.g. cylindrical axonal bundles in white matter) and magnetic susceptibility anisotropy...
November 11, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27859861/development-of-a-7%C3%A2-t-rf-coil-system-for-breast-imaging
#8
Junghwan Kim, Tales Santini, Kyongtae Ty Bae, Narayan Krishnamurthy, Yujuan Zhao, Tiejun Zhao, Tamer S Ibrahim
In ultrahigh-field MRI, such as 7 T, the signal-to-noise ratio (SNR) increases while transmit (Tx) field (B1(+) ) can be degraded due to inhomogeneity and elevated specific absorption rate (SAR). By applying new array coil concepts to both Tx and receive (Rx) coils, the B1(+) homogeneity and SNR can be improved. In this study, we developed and tested in vivo a new RF coil system for 7 T breast MRI. An RF coil system composed of an eight-channel Tx-only array based on a tic-tac-toe design (can be combined to operate in single-Tx mode) in conjunction with an eight-channel Rx-only insert was developed...
November 11, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27859844/in-vivo-estimation-of-gamma-aminobutyric-acid-levels-in-the-neonatal-brain
#9
Moyoko Tomiyasu, Noriko Aida, Jun Shibasaki, Masahiro Umeda, Katsutoshi Murata, Keith Heberlein, Mark A Brown, Eiji Shimizu, Hiroshi Tsuji, Takayuki Obata
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain, and plays a key role in brain development. However, the in vivo levels of brain GABA in early life are unknown. Using edited MRS, in vivo GABA can be detected as GABA+ signal with contamination of macromolecule signals. GABA+ is evaluated as the peak ratio of GABA+/reference compound, for which creatine (Cr) or water is typically used. However, the concentrations and T1 and T2 relaxation times of these references change during development...
November 11, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27859838/aggregation-induced-changes-in-the-chemical-exchange-saturation-transfer-cest-signals-of-proteins
#10
Steffen Goerke, Katharina S Milde, Raul Bukowiecki, Patrick Kunz, Karel D Klika, Thomas Wiglenda, Axel Mogk, Erich E Wanker, Bernd Bukau, Mark E Ladd, Peter Bachert, Moritz Zaiss
Chemical exchange saturation transfer (CEST) is an MRI technique that allows mapping of biomolecules (small metabolites, proteins) with nearly the sensitivity of conventional water proton MRI. In living organisms, several tissue-specific CEST effects have been observed and successfully applied to diagnostic imaging. In these studies, particularly the signals of proteins showed a distinct correlation with pathological changes. However, as CEST effects depend on various properties that determine and affect the chemical exchange processes, the origins of the observed signal changes remain to be understood...
November 11, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27862471/assessment-of-passive-muscle-elongation-using-diffusion-tensor-mri-correlation-between-fiber-length-and-diffusion-coefficients
#11
Valentina Mazzoli, Jos Oudeman, Klaas Nicolay, Mario Maas, Nico Verdonschot, Andre M Sprengers, Aart J Nederveen, Martijn Froeling, Gustav J Strijkers
In this study we investigated the changes in fiber length and diffusion parameters as a consequence of passive lengthening and stretching of the calf muscles. We hypothesized that changes in radial diffusivity (RD) are caused by changes in the muscle fiber cross sectional area (CSA) as a consequence of lengthening and shortening of the muscle. Diffusion Tensor MRI (DT-MRI) measurements were made twice in five healthy volunteers, with the foot in three different positions (30° plantarflexion, neutral position and 15° dorsiflexion)...
November 8, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27809405/pulmonary-perfusion-quantification-with-flow-sensitive-inversion-recovery-fair-ute-mri-in-small-animal-imaging
#12
Marta Tibiletti, Andrea Bianchi, Detlef Stiller, Volker Rasche
Blood perfusion in lung parenchyma is an important property for assessing lung function. In small animals, its quantitation is limited even with radioactive isotopes or dynamic contrast-enhanced MRI techniques. In this study, the feasibility flow-sensitive alternating inversion recovery (FAIR) for the quantification of blood flow in lung parenchyma in free breathing rats at 7 T has been investigated. In order to obtain sufficient signal from the short T2 * lung parenchyma, a 2D ultra-short echo time (UTE) Look-Locker read-out has been implemented...
November 3, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27809383/ultra-high-field-rf-coil-development-for-evaluating-upper-extremity-imaging-applications
#13
Shailesh B Raval, Tiejun Zhao, Narayanan Krishnamurthy, Tales Santini, Cynthia Britton, Vijay S Gorantla, Tamer S Ibrahim
The purpose of this study is to develop and evaluate a custom-designed 7  T MRI coil and explore its use for upper extremity applications. An RF system composed of a transverse electromagnetic transmit coil and an eight-channel receive-only array was developed for 7  T upper extremity applications. The RF system was characterized and evaluated using scattering parameters and B1(+) mapping. Finite difference time domain simulations were performed to evaluate the B1(+) field distribution and specific absorption rate for the forearm region of the upper extremity...
November 3, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27809376/an-in-vivo-study-of-the-orientation-dependent-and-independent-components-of-transverse-relaxation-rates-in-white-matter
#14
Rita Gil, Diana Khabipova, Marcel Zwiers, Tom Hilbert, Tobias Kober, José P Marques
Diffusion-weighted imaging (DWI) provides information that allows the estimation of white-matter (WM) fibre orientation and distribution, but it does not provide information about myelin density, fibre concentration or fibre size within each voxel. On the other hand, quantitative relaxation contrasts (like the apparent transverse relaxation, R2∗) offer iron and myelin-related contrast, but their dependence on the orientation of microstructure with respect to the applied magnetic field, B0 , is often neglected...
November 3, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27779348/simultaneous-detection-of-valine-and-lactate-using-mega-press-editing-in-pyogenic-brain-abscess
#15
Thomas Lange, Cheng-Wen Ko, Ping-Hong Lai, Michael Dacko, Shang-Yueh Tsai, Martin Buechert
Valine and lactate have been recognized as important metabolic markers to diagnose brain abscess by means of MRS. However, in vivo unambiguous detection and quantification is hampered by macromolecular contamination. In this work, MEGA-PRESS difference editing of valine and lactate is proposed. The method is validated in vitro and applied for quantitative in vivo experiments in one healthy subject and two brain abscess patients. It is demonstrated that with this technique the overlapping lipid signal can be reduced by more than an order of magnitude and thus the robustness of valine and lactate detection in vivo can be enhanced...
October 25, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27779341/study-of-neurometabolic-and-behavioral-alterations-in-rodent-model-of-mild-traumatic-brain-injury-a-pilot-study
#16
Kavita Singh, Richa Trivedi, Seenu Haridas, Kailash Manda, Subash Khushu
Mild traumatic brain injury (mTBI) is the most common form of TBI (70-90%) with consequences of anxiety-like behavioral alterations in approximately 23% of mTBI cases. This study aimed to assess whether mTBI-induced anxiety-like behavior is a consequence of neurometabolic alterations. mTBI was induced using a weight drop model to simulate mild human brain injury in rodents. Based on injury induction and dosage of anesthesia, four animal groups were included in this study: (i) injury with anesthesia (IA); (ii) sham1 (injury only, IO); (iii) sham2 (only anesthesia, OA); and (iv) control rats...
October 25, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27779334/simultaneous-in-vivo-assessment-of-cardiac-and-hepatic-metabolism-in-the-diabetic-rat-using-hyperpolarized-mrs
#17
Lydia M Le Page, Daniel R Ball, Vicky Ball, Michael S Dodd, Jack J Miller, Lisa C Heather, Damian J Tyler
Understanding and assessing diabetic metabolism is vital for monitoring disease progression and improving treatment of patients. In vivo assessments, using MRI and MRS, provide non-invasive and accurate measurements, and the development of hyperpolarized (13) C spectroscopy in particular has been demonstrated to provide valuable metabolic data in real time. Until now, studies have focussed on individual organs. However, diabetes is a systemic disease affecting multiple tissues in the body. Therefore, we have developed a technique to simultaneously measure metabolism in both the heart and liver during a single acquisition...
October 25, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27763692/accelerated-mapping-of-magnetic-susceptibility-using-3d-planes-on-a-paddlewheel-pop-epi-at-ultra-high-field-strength
#18
Daniel Stäb, Steffen Bollmann, Christian Langkammer, Kristian Bredies, Markus Barth
With the advent of ultra-high field MRI scanners in clinical research, susceptibility based MRI has recently gained increasing interest because of its potential to assess subtle tissue changes underlying neurological pathologies/disorders. Conventional, but rather slow, three-dimensional (3D) spoiled gradient-echo (GRE) sequences are typically employed to assess the susceptibility of tissue. 3D echo-planar imaging (EPI) represents a fast alternative but generally comes with echo-time restrictions, geometrical distortions and signal dropouts that can become severe at ultra-high fields...
October 20, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27753155/post-contractile-bold-contrast-in-skeletal-muscle-at-7%C3%A2-t-reveals-inter-individual-heterogeneity-in-the-physiological-responses-to-muscle-contraction
#19
Theodore F Towse, Christopher P Elder, Emily C Bush, Samuel W Klockenkemper, Jared T Bullock, Richard D Dortch, Bruce M Damon
Muscle blood oxygenation-level dependent (BOLD) contrast is greater in magnitude and potentially more influenced by extravascular BOLD mechanisms at 7 T than it is at lower field strengths. Muscle BOLD imaging of muscle contractions at 7 T could, therefore, provide greater or different contrast than at 3 T. The purpose of this study was to evaluate the feasibility of using BOLD imaging at 7 T to assess the physiological responses to in vivo muscle contractions. Thirteen subjects (four females) performed a series of isometric contractions of the calf muscles while being scanned in a Philips Achieva 7 T human imager...
October 18, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27731914/magnetic-resonance-imaging-of-ischemic-injury-produced-by-varying-severities-of-photothrombosis-differs-in-neonatal-and-adult-brain
#20
Ursula I Tuor, Min Qiao, Manasi Sule, Melissa Morgunov, Tadeusz Foniok
Stroke is a major cause of disability in adults and children. Recently, we have developed an adult rat model of minor stroke containing a peri-infarct region with a modest T2 increase and mild ischemic damage. We hypothesized that a neonatal minor stroke with mild peri-ischemic changes could also be produced, but with potential ontogenic differences. Using our minor photothrombosis method, we produced a range of severities of ischemic lesions (mini, minor, moderate and severe) within magnetic resonance imaging (MRI) slices of adult and neonatal rats...
October 12, 2016: NMR in Biomedicine
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