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NMR in Biomedicine

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https://www.readbyqxmd.com/read/28548710/measurement-of-glycine-in-healthy-and-tumorous-brain-by-triple-refocusing-mrs-at-3%C3%A2-t-in-vivo
#1
Vivek Tiwari, Zhongxu An, Sandeep K Ganji, Jeannie Baxter, Toral R Patel, Edward Pan, Bruce E Mickey, Elizabeth A Maher, Marco C Pinho, Changho Choi
Glycine (Gly) has been implicated in several neurological disorders, including malignant brain tumors. The precise measurement of Gly is challenging largely as a result of the spectral overlap with myo-inositol (mI). We report a new triple-refocusing sequence for the reliable co-detection of Gly and mI at 3 T and for the evaluation of Gly in healthy and tumorous brain. The sequence parameters were optimized with density-matrix simulations and phantom validation. With a total TE of 134 ms, the sequence gave complete suppression of the mI signal between 3...
May 26, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543885/dce-mri-prediction-of-survival-time-for-patients-with-glioblastoma-multiforme-using-an-adaptive-neuro-fuzzy-based-model-and-nested-model-selection-technique
#2
Azimeh N V Dehkordi, Alireza Kamali-Asl, Ning Wen, Tom Mikkelsen, Indrin J Chetty, Hassan Bagher-Ebadian
This pilot study investigates the construction of an Adaptive Neuro-Fuzzy Inference System (ANFIS) for the prediction of the survival time of patients with glioblastoma multiforme (GBM). ANFIS is trained by the pharmacokinetic (PK) parameters estimated by the model selection (MS) technique in dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) data analysis, and patient age. DCE-MRI investigations of 33 treatment-naïve patients with GBM were studied. Using the modified Tofts model and MS technique, the following physiologically nested models were constructed: Model 1, no vascular leakage (normal tissue); Model 2, leakage without efflux; Model 3, leakage with bidirectional exchange (influx and efflux)...
May 25, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543814/intra-and-interindividual-variability-of-fatty-acid-unsaturation-in-six-different-human-adipose-tissue-compartments-assessed-by-1-h-mrs-in-vivo-at-3%C3%A2-t
#3
Jürgen Machann, Norbert Stefan, Robert Wagner, Malte Bongers, Erwin Schleicher, Andreas Fritsche, Hans-Ulrich Häring, Konstantin Nikolaou, Fritz Schick
It is generally accepted that the amount and distribution of adipose tissue (AT) in the human body play an important role in the pathogenesis of metabolic diseases. In addition, metabolic effects of released saturated fatty acids (FAs) in blood are known to be more critical than those of unsaturated FAs. However, little is known about the variability in unsaturation of FAs in various AT compartments. The aim of this prospective study was the assessment of mono- and polyunsaturated FAs in various AT compartments by localized (1) H-MRS in order to obtain insight into the intra- and interindividual variability...
May 25, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543797/simultaneous-use-of-linear-and-nonlinear-gradients-for-b1-inhomogeneity-correction
#4
Koray Ertan, Ergin Atalar
The simultaneous use of linear spatial encoding magnetic fields (L-SEMs) and nonlinear spatial encoding magnetic fields (N-SEMs) in B1(+) inhomogeneity problems is formulated and demonstrated with both simulations and experiments. Independent excitation k-space variables for N-SEMs are formulated for the simultaneous use of L-SEMs and N-SEMs by assuming a small tip angle. The formulation shows that, when N-SEMs are considered as an independent excitation k-space variable, numerous different k-space trajectories and frequency weightings differing in dimension, length, and energy can be designed for a given target transverse magnetization distribution...
May 25, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543787/accurate-determination-of-brain-metabolite-concentrations-using-eretic-as-external-reference
#5
Niklaus Zoelch, Andreas Hock, Susanne Heinzer-Schweizer, Nikolai Avdievitch, Anke Henning
Magnetic Resonance Spectroscopy (MRS) can provide in vivo metabolite concentrations in standard concentration units if a reliable reference signal is available. For (1) H MRS in the human brain, typically the signal from the tissue water is used as the (internal) reference signal. However, a concentration determination based on the tissue water signal most often requires a reliable estimate of the water concentration present in the investigated tissue. Especially in clinically interesting cases, this estimation might be difficult...
May 25, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28544012/comments-on-tumor-apparent-diffusion-coefficient-as-an-imaging-biomarker-to-predict-tumor-aggressiveness
#6
LETTER
Li Xu, Rong-Pin Wang, SiWei Zhang, Zhi-Guang Chen
No abstract text is available yet for this article.
May 24, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543921/correlations-of-low-field-nmr-and-variable-field-nmr-parameters-with-osteoarthritis-in-human-articular-cartilage-under-load
#7
Erik Rössler, Carlos Mattea, Simo Saarakkala, Petri Lehenkari, Mikko Finnilä, Lassi Rieppo, Sakari Karhula, Miika T Nieminen, Siegfried Stapf
NMR experiments carried out at magnetic fields below 1 T provide new relaxation parameters unavailable with conventional clinical scanners. Contrast of T1 generally becomes larger towards low fields, as slow molecular reorientation processes dominate relaxation at the corresponding Larmor frequencies. This advantage has to be considered in the context of lower sensitivity and frequently reduced spatial resolution. The layered structure of cartilage is one example where a particularly strong variation of T1 across the tissue occurs, being affected by degenerative diseases such as osteoarthritis (OA)...
May 24, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543840/imaging-of-nuclear-overhauser-enhancement-at-7-and-3%C3%A2-t
#8
Yuanyu Shen, Gang Xiao, Zhiwei Shen, Xiaolei Zhang, Xiangyong Tang, Wei Hu, Zhiyan Zhang, Jitian Guan, Renhua Wu
Nuclear Overhauser enhancement (NOE) is a type of magnetization transfer using cross-relaxation. It originates from mobile macromolecules, which may have relevance to the evaluation of tumor features. We studied the value of NOE imaging at 7 and 3 T and suggest a utility for diagnosing human brain tumors. Two types of protein solution at different concentrations and pH values, and six normal Sprague Dawley (SD) rats, were used to detect NOE signal with a 7 T scanner. Then, six healthy volunteers and 11 patients with brain tumors (six gliomas and five meningiomas) were included at 3 T...
May 24, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543640/electric-properties-tomography-biochemical-physical-and-technical-background-evaluation-and-clinical-applications
#9
REVIEW
Ulrich Katscher, Cornelius A T van den Berg
Electric properties tomography (EPT) derives the patient's electric properties, i.e. conductivity and permittivity, using standard magnetic resonance (MR) systems and standard MR sequences. Thus, EPT does not apply externally mounted electrodes, currents or radiofrequency (RF) probes, as is the case in competing techniques. EPT is quantitative MR, i.e. it yields absolute values of conductivity and permittivity. This review summarizes the physical equations underlying EPT, the corresponding basic and advanced reconstruction techniques and practical numerical aspects to realize these reconstruction techniques...
May 24, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28544286/early-regional-cuprizone-induced-demyelination-in-a-rat-model-revealed-with-mri
#10
Wendy Oakden, Nicholas A Bock, Alia Al-Ebraheem, Michael J Farquharson, Greg J Stanisz
The cuprizone model of demyelination is well established in the mouse as a tool for the study of the mechanisms of both demyelination and remyelination. It is often desirable, however, to have a larger model, such as the rat, especially for imaging-based studies, yet initial work has failed to show demyelination in cuprizone-fed rats. Several recent studies have demonstrated demyelination in the rat, but only in the corpus callosum. In this study, we acquired high-resolution, three-dimensional images of the whole brain every 2 weeks, using a T1 -weighted magnetization-prepared rapid acquisition gradient echo imaging sequence, optimized for myelin contrast, in order to assess myelination across the entire rat brain over a period of 8 weeks on a 1% cuprizone diet...
May 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28544159/simultaneous-measurement-of-t1-b1-and-pharmacokinetic-model-parameters-using-active-contrast-encoding-ace-mri
#11
Jin Zhang, Kerryanne Winters, Olivier Reynaud, Sungheon Gene Kim
The aim of this study was to assess the feasibility of combining dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) with the measurement of the radiofrequency (RF) transmit field B1 and pre-contrast longitudinal relaxation time T10 . A novel approach has been proposed to simultaneously estimate B1 and T10 from a modified DCE-MRI scan that actively encodes the washout phase of the curve with different amounts of T1 and B1 weighting using multiple flip angles and repetition times, hence referred to as active contrast encoding (ACE)-MRI...
May 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28544035/chemical-exchange-sensitive-mri-of-amide-amine-and-noe-at-9-4%C3%A2-t-versus-15-2%C3%A2-t
#12
Julius Juhyun Chung, Wonmin Choi, Tao Jin, Jung Hee Lee, Seong-Gi Kim
Chemical exchange (CE)-sensitive MRI benefits greatly from stronger magnetic fields; however, field effects on CE-sensitive imaging have not yet been studied well in vivo. We have compared CE-sensitive Z-spectra and maps obtained at the fields of 9.4 T and 15.2 T in phantoms and rats with off-resonance chemical-exchange-sensitive spin lock (CESL), which is similar to conventional chemical exchange saturation transfer. At higher fields, the background peak at water resonance has less spread and the exchange rate relative to chemical shift decreases, thus CESL intensity is dependent on B0 ...
May 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543843/white-matter-biomarkers-from-fast-protocols-using-axially-symmetric-diffusion-kurtosis-imaging
#13
Brian Hansen, Ahmad R Khan, Noam Shemesh, Torben E Lund, Ryan Sangill, Simon F Eskildsen, Leif Østergaard, Sune N Jespersen
White matter tract integrity (WMTI) can characterize brain microstructure in areas with highly aligned fiber bundles. Several WMTI biomarkers have now been validated against microscopy and provided promising results in studies of brain development and aging, as well as in a number of brain disorders. Currently, WMTI is mostly used in dedicated animal studies and clinical studies of slowly progressing diseases, and has not yet emerged as a routine clinical tool. To this end, a less data intensive experimental method would be beneficial by enabling high resolution validation studies, and ease clinical applications by speeding up data acquisition compared with typical diffusion kurtosis imaging (DKI) protocols utilized as part of WMTI imaging...
May 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28543772/parp-inhibitor-rucaparib-induces-changes-in-nad-levels-in-cells-and-liver-tissues-as-assessed-by-mrs
#14
Gilberto S Almeida, Carlo M Bawn, Martin Galler, Ian Wilson, Huw D Thomas, Suzanne Kyle, Nicola J Curtin, David R Newell, Ross J Maxwell
Poly(adenosine diphosphate ribose) polymerases (PARPs) are multifunctional proteins which play a role in many cellular processes. Namely, PARP1 and PARP2 have been shown to be involved in DNA repair, and therefore are valid targets in cancer treatment with PARP inhibitors, such as rucaparib, currently in clinical trials. Proton magnetic resonance spectroscopy ((1) H-MRS) was used to study the impact of rucaparib in vitro and ex vivo in liver tissue from mice, via quantitative analysis of nicotinamide adenosine diphosphate (NAD(+) ) spectra, to assess the potential of MRS as a biomarker of the PARP inhibitor response...
May 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28508450/simultaneous-assessment-of-both-lung-morphometry-and-gas-exchange-function-within-a-single-breath-hold-by-hyperpolarized-129-xe-mri
#15
Jianping Zhong, Huiting Zhang, Weiwei Ruan, Junshuai Xie, Haidong Li, He Deng, Yeqing Han, Xianping Sun, Chaohui Ye, Xin Zhou
During the measurement of hyperpolarized (129) Xe magnetic resonance imaging (MRI), the diffusion-weighted imaging (DWI) technique provides valuable information for the assessment of lung morphometry at the alveolar level, whereas the chemical shift saturation recovery (CSSR) technique can evaluate the gas exchange function of the lungs. To date, the two techniques have only been performed during separate breaths. However, the request for multiple breaths increases the cost and scanning time, limiting clinical application...
May 16, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28481039/covariance-j-resolved-spectroscopy-theory-and-application-in-vivo
#16
Zohaib Iqbal, Gaurav Verma, Anand Kumar, M Albert Thomas
Magnetic resonance spectroscopy (MRS) is a powerful tool capable of investigating the metabolic status of several tissues in vivo. In particular, single-voxel-based (1) H spectroscopy provides invaluable biochemical information from a volume of interest (VOI) and has therefore been used in a variety of studies. Unfortunately, typical one-dimensional MRS data suffer from severe signal overlap and thus important metabolites are difficult to distinguish. One method that is used to disentangle overlapping resonances is the two-dimensional J-resolved spectroscopy (JPRESS) experiment...
May 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28481037/regional-quantification-of-myocardial-mechanics-in-rat-using-3d-cine-dense-cardiovascular-magnetic-resonance
#17
Xiaoyan Zhang, Zhan-Qiu Liu, Dara Singh, Gregory J Wehner, David K Powell, Kenneth S Campbell, Brandon K Fornwalt, Jonathan F Wenk
Rat models have assumed an increasingly important role in cardiac research. However, a detailed profile of regional cardiac mechanics, such as strains and torsion, is lacking for rats. We hypothesized that healthy rat left ventricles (LVs) exhibit regional differences in cardiac mechanics, which are part of normal function. In this study, images of the LV were obtained with 3D cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance in 10 healthy rats. To evaluate regional cardiac mechanics, the LV was divided into basal, mid-ventricular, and apical regions...
May 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28470823/modifications-of-pancreatic-diffusion-mri-by-tissue-characteristics-what-are-we-weighting-for
#18
REVIEW
Noam Nissan
Diffusion-weighted imaging holds the potential to improve the diagnosis and biological characterization of pancreatic disease, and in particular pancreatic cancer, which exhibits decreased values of the apparent diffusion coefficient (ADC). Yet, variable and overlapping ADC values have been reported for the healthy and the pathological pancreas, including for cancer and other benign conditions. This controversy reflects the complexity of probing the water-diffusion process in the pancreas, which is dependent upon multiple biological factors within this organ's unique physiological environment...
May 4, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28470768/susceptibility-sensitive-mri-of-multiple-sclerosis-lesions-and-the-impact-of-normal-appearing-white-matter-changes
#19
Vanessa Wiggermann, Simon Hametner, Enedino Hernández-Torres, Christian Kames, Verena Endmayr, Gregor Kasprian, Romana Höftberger, David K B Li, Anthony Traboulsee, Alexander Rauscher
Susceptibility-sensitive magnetic resonance imaging (MRI) has gained importance in multiple sclerosis (MS) research because of its versatility, high resolution and excellent sensitivity to changes in tissue structure and composition. In particular, mapping of the resonance frequency of the MR signal and quantitative susceptibility mapping (QSM) have been explored for the description of MS lesions. Many current studies utilizing these techniques attribute increases in the MR frequency or QSM to elevated tissue iron content, in addition to myelin loss...
May 4, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28430379/-17-o-mrs-assesses-the-effect-of-mild-hypothermia-on-oxygen-consumption-rate-in-tumors
#20
Marie-Aline Neveu, Nicolas Joudiou, Géraldine De Preter, Jean-Paul Dehoux, Bénédicte F Jordan, Bernard Gallez
Although oxygen consumption is a key factor in metabolic phenotyping, its assessment in tumors remains critical, as current technologies generally display poor specificity. The objectives of this study were to explore the feasibility of direct (17) O nuclear magnetic resonance (NMR) spectroscopy to assess oxygen metabolism in tumors and its modulations. To investigate the impact of hypometabolism induction in the murine fibrosarcoma FSAII tumor model, we monitored the oxygen consumption of normothermic (37°C) and hypothermic (32°C) tumor-bearing mice...
April 21, 2017: NMR in Biomedicine
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