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NMR in Biomedicine

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https://www.readbyqxmd.com/read/28805936/characterizing-hypoxia-in-human-glioma-a-simultaneous-multimodal-mri-and-pet-study
#1
Christine Preibisch, Kuangyu Shi, Anne Kluge, Mathias Lukas, Benedikt Wiestler, Jens Göttler, Jens Gempt, Florian Ringel, Mohamed Al Jaberi, Jürgen Schlegel, Bernhard Meyer, Claus Zimmer, Thomas Pyka, Stefan Förster
Hypoxia plays an important role for the prognosis and therapy response of cancer. Thus, hypoxia imaging would be a valuable tool for pre-therapeutic assessment of tumor malignancy. However, there is no standard validated technique for clinical application available yet. Therefore, we performed a study in 12 patients with high-grade glioma, where we directly compared the two currently most promising techniques, namely the MR-based relative oxygen extraction fraction (MR-rOEF) and the PET hypoxia marker H-1-(3-[(18) F]-fluoro-2-hydroxypropyl)-2-nitroimidazole ([(18) F]-FMISO)...
August 14, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28796397/clinical-evaluation-of-time-of-flight-mr-angiography-with-sparse-undersampling-and-iterative-reconstruction-for-cerebral-aneurysms
#2
Yasutaka Fushimi, Tomohisa Okada, Takayuki Kikuchi, Akira Yamamoto, Tsutomu Okada, Takayuki Yamamoto, Michaela Schmidt, Kazumichi Yoshida, Susumu Miyamoto, Kaori Togashi
Compressed sensing (CS) MRI has just been introduced to research areas as an innovative approach to accelerate MRI. CS is expected to achieve higher k-space undersampling by exploiting the underlying sparsity in an appropriate transform domain. MR angiography (MRA) provides high spatial resolution information on arteries; however, a relatively long acquisition time is necessary to cover a wide volume. Reduction of acquisition time by CS for time-of-flight (TOF) MR angiography (Sparse-TOF) is beneficial in clinical examinations; therefore, the clinical validity of Sparse-TOF needs to be investigated...
August 10, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28796319/diffusion-weighted-mrs-of-acetate-in-the-rat-brain
#3
Masoumeh Dehghani, Nicolas Kunz, Bernard Lanz, Hikari A I Yoshihara, Rolf Gruetter
Acetate has been proposed as an astrocyte-specific energy substrate for metabolic studies in the brain. The determination of the relative contribution of the intracellular and extracellular compartments to the acetate signal using diffusion-weighted magnetic resonance spectroscopy can provide an insight into the cellular environment and distribution volume of acetate in the brain. In the present study, localized (1) H nuclear magnetic resonance (NMR) spectroscopy employing a diffusion-weighted stimulated echo acquisition mode (STEAM) sequence at an ultra-high magnetic field (14...
August 10, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28777496/t2-mapping-with-magnetization-prepared-3d-tse-based-on-a-modified-bir-4%C3%A2-t2-preparation
#4
Dominik Weidlich, Sarah Schlaeger, Hendrik Kooijman, Peter Börnert, Jan S Kirschke, Ernst J Rummeny, Axel Haase, Dimitrios C Karampinos
The purpose of this work was to investigate the performance of the modified BIR-4 T2 preparation for T2 mapping and propose a method to remove T2 quantification errors in the presence of large B1 and B0 offsets. The theoretical investigation of the magnetization evolution during the T2 preparation in the presence of B1 and B0 offsets showed deviations from a mono-exponential T2 decay (two parameter fit). A three parameter fit was used to improve T2 accuracy. Furthermore, a two parameter fit with an additional saturation preparation scan was proposed to improve T2 accuracy and precision...
August 4, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28759166/altered-metabolites-of-the-rat-hippocampus-after-mild-and-moderate-traumatic-brain-injury-a-combined-in-vivo-and-in-vitro-1-h-mrs-study
#5
Kavita Singh, Richa Trivedi, Ajay Verma, Maria M D'souza, Sunil Koundal, Poonam Rana, Bikash Baishya, Subash Khushu
Traumatic brain injury (TBI) has been shown to affect hippocampus-associated learning, memory and higher cognitive functions, which may be a consequence of metabolic alterations. Hippocampus-associated disorders may vary depending on the severity of injury [mild TBI (miTBI) and moderate TBI (moTBI)] and time since injury. The underlying hippocampal metabolic irregularities may provide an insight into the pathological process following TBI. In this study, in vivo and in vitro proton magnetic resonance spectroscopy ((1) H-MRS) data were acquired from the hippocampus region of controls and TBI groups (miTBI and moTBI) at D0 (pre-injury), 4 h, Day 1 and Day 5 post-injury (PI)...
July 31, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28731616/inversion-recovery-ultrashort-echo-time-imaging-of-ultrashort-t2-tissue-components-in-ovine-brain-at-3%C3%A2-t-a-sequential-d2-o-exchange-study
#6
Shu-Juan Fan, Yajun Ma, Eric Y Chang, Graeme M Bydder, Jiang Du
Inversion recovery ultrashort echo time (IR-UTE) imaging holds the potential to directly characterize MR signals from ultrashort T2 tissue components (STCs), such as collagen in cartilage and myelin in brain. The application of IR-UTE for myelin imaging has been challenging because of the high water content in brain and the possibility that the ultrashort T2 * signals are contaminated by water protons, including those associated with myelin sheaths. This study investigated such a possibility in an ovine brain D2 O exchange model and explored the potential of IR-UTE imaging for the quantification of ultrashort T2 * signals in both white and gray matter at 3 T...
July 21, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28731544/localized-mrs-reliability-of-in-vivo-glutamate-at-3%C3%A2-t-in-shortened-scan-times-a-feasibility-study
#7
J Eric Jensen, Randy P Auerbach, Angela Pisoni, Diego A Pizzagalli
Glutamate is the prime excitatory neurotransmitter in the mammalian brain and has been implicated in a wide range of psychiatric conditions. To improve the applicability and clinical reach of magnetic resonance spectroscopy (MRS), research is needed to develop shortened, yet reliable, MRS scanning procedures for standard 1.5-3-T clinical magnetic resonance imaging (MRI) systems, particularly with young or vulnerable populations unable to tolerate longer protocols. To this end, we evaluated the test-retest reliability of a shortened J-resolved MRS sequence in healthy adolescents (n = 22) aged 12-14 years...
July 21, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28708304/hyperpolarized-13-c-magnetic-resonance-evaluation-of-renal-ischemia-reperfusion-injury-in-a-murine-model
#8
Celine Baligand, Hecong Qin, Aisha True-Yasaki, Jeremy W Gordon, Cornelius von Morze, Justin Delos Santos, David M Wilson, Robert Raffai, Patrick M Cowley, Anthony J Baker, John Kurhanewicz, David H Lovett, Zhen Jane Wang
Acute kidney injury (AKI) is a major risk factor for the development of chronic kidney disease (CKD). Persistent oxidative stress and mitochondrial dysfunction are implicated across diverse forms of AKI and in the transition to CKD. In this study, we applied hyperpolarized (HP) (13) C dehydroascorbate (DHA) and (13) C pyruvate magnetic resonance spectroscopy (MRS) to investigate the renal redox capacity and mitochondrial pyruvate dehydrogenase (PDH) activity, respectively, in a murine model of AKI at baseline and 7 days after unilateral ischemia reperfusion injury (IRI)...
July 14, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28703331/high-resolution-diffusion-tensor-imaging-in-cervical-spondylotic-myelopathy-a-preliminary-follow-up-study
#9
Li Guan, Xiaolong Chen, Yong Hai, Xiaodong Ma, Le He, Guangzhi Wang, Chun Yuan, Hua Guo
Diffusion imaging is a promising technique as it can provide microstructural tissue information and thus potentially show viable changes in spinal cord. However, the traditional single-shot imaging method is limited as a result of various image artifacts. In order to improve measurement accuracy, we used a newly developed, multi-shot, high-resolution, diffusion tensor imaging (DTI) method to investigate diffusion metric changes and compare them with T2 -weighted (T2W) images before and after decompressive surgery for cervical spondylotic myelopathy (CSM)...
July 13, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28696013/the-role-of-diffusion-mri-in-neuroscience
#10
Yaniv Assaf, Heidi Johansen-Berg, Michel Thiebaut de Schotten
Diffusion-weighted imaging has pushed the boundaries of neuroscience by allowing us to examine the white matter microstructure of the living human brain. By doing so, it has provided answers to fundamental neuroscientific questions, launching a new field of research that had been largely inaccessible. We briefly summarize key questions that have historically been raised in neuroscience concerning the brain's white matter. We then expand on the benefits of diffusion-weighted imaging and its contribution to the fields of brain anatomy, functional models and plasticity...
July 11, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28686319/magnetic-resonance-thermometry-of-flowing-blood
#11
Chinthaka C Heyn, Jonathan Bishop, Kyle Duffin, Wayne Lee, Jun Dazai, Shoshana Spring, Brian J Nieman, John G Sled
Blood temperature is a key determinant of tissue temperature and can be altered under normal physiological states, such as exercise, in diseases such as stroke or iatrogenically in therapies which modulate tissue temperature, such as therapeutic hypothermia. Currently available methods for the measurement of arterial and venous temperatures are invasive and, for small animal models, are impractical. Here, we present a methodology for the measurement of intravascular and tissue temperature by magnetic resonance imaging (MRI) using the lanthanide agent TmDOTMA(-) (DOTMA, tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; Tm, thulium)...
July 7, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28678429/global-brain-metabolic-quantification-with-whole-head-proton-mrs-at-3%C3%A2-t
#12
Ivan I Kirov, William E Wu, Brian J Soher, Matthew S Davitz, Jeffrey H Huang, James S Babb, Mariana Lazar, Girish Fatterpekar, Oded Gonen
Total N-acetyl-aspartate + N-acetyl-aspartate-glutamate (NAA), total creatine (Cr) and total choline (Cho) proton MRS ((1) H-MRS) signals are often used as surrogate markers in diffuse neurological pathologies, but spatial coverage of this methodology is limited to 1%-65% of the brain. Here we wish to demonstrate that non-localized, whole-head (WH) (1) H-MRS captures just the brain's contribution to the Cho and Cr signals, ignoring all other compartments. Towards this end, 27 young healthy adults (18 men, 9 women), 29...
July 5, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28678410/simultaneous-mr-quantification-of-hepatic-fat-content-fatty-acid-composition-transverse-relaxation-time-and-magnetic-susceptibility-for-the-diagnosis-of-non-alcoholic-steatohepatitis
#13
B Leporq, S A Lambert, M Ronot, V Vilgrain, B E Van Beers
Non-alcoholic steatohepatitis (NASH) is characterized at histology by steatosis, hepatocyte ballooning and inflammatory infiltrates, with or without fibrosis. Although diamagnetic material in fibrosis and inflammation can be detected with quantitative susceptibility imaging, fatty acid composition changes in NASH relative to simple steatosis have also been reported. Therefore, our aim was to develop a single magnetic resonance (MR) acquisition and post-processing scheme for the diagnosis of steatohepatitis by the simultaneous quantification of hepatic fat content, fatty acid composition, T2 * transverse relaxation time and magnetic susceptibility in patients with non-alcoholic fatty liver disease...
July 5, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28678353/feedback-field-control-improves-the-precision-of-t2-quantification-at-7%C3%A2-t
#14
Michael Wyss, Yolanda Duerst, Daniel Nanz, Lars Kasper, Bertram Jakob Wilm, Benjamin Emmanuel Dietrich, Simon Gross, Thomas Schmid, David Otto Brunner, Klaas Paul Pruessmann
T2 * mapping offers access to a number of important structural and physiological tissue parameters. It is robust against RF field variations and overall signal scaling. However, T2 * measurement is highly sensitive to magnetic field errors, including perturbations caused by breathing motion at high baseline field. The goal of this work is to assess this issue in T2 * mapping of the brain and to study the benefit of field stabilization by feedback field control. T2 * quantification in the brain was investigated by phantom and in vivo measurements at 7 T...
July 5, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28665041/measurement-and-modeling-of-diffusion-time-dependence-of-apparent-diffusion-coefficient-and-fractional-anisotropy-in-prostate-tissue-ex-vivo
#15
Roger Bourne, Sisi Liang, Eleftheria Panagiotaki, Andre Bongers, Paul Sved, Geoffrey Watson
The purpose of this study was to measure and model the diffusion time dependence of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) derived from conventional prostate diffusion-weighted imaging methods as used in recommended multiparametric MRI protocols. Diffusion tensor imaging (DTI) was performed at 9.4 T with three radical prostatectomy specimens, with diffusion times in the range 10-120 ms and b-values 0-3000 s/mm(2) . ADC and FA were calculated from DTI measurements at b-values of 800 and 1600 s/mm(2) ...
June 30, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28661075/mri-reveals-increased-tumorigenesis-following-high-fat-feeding-in-a-mouse-model-of-triple-negative-breast-cancer
#16
Devkumar Mustafi, Sully Fernandez, Erica Markiewicz, Xiaobing Fan, Marta Zamora, Jeffrey Mueller, Matthew J Brady, Suzanne D Conzen, Gregory S Karczmar
High animal fat consumption is associated with an increase in triple-negative breast cancer (TNBC) risk. Based on previous MRI studies demonstrating the feasibility of detecting very early non-palpable mammary cancers in simian virus 40 large T antigen (SV40TAg) mice, we examined the effect of dietary fat fed from weaning to young adulthood in this model of TNBC. Virgin female C3(1)SV40TAg mice (n = 16) were weaned at 3-4 weeks of age and then fed either a low fat diet (LFD) (n = 8, 3.7 kcal/g; 17.2% kcal from vegetable oil) or a high animal fat diet (HAFD) (n = 8, 5...
June 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28661067/medial-prefrontal-cortex-deficits-correlate-with-unrefreshing-sleep-in-patients-with-chronic-fatigue-syndrome
#17
Zack Y Shan, Richard Kwiatek, Richard Burnet, Peter Del Fante, Donald R Staines, Sonya M Marshall-Gradisnik, Leighton R Barnden
Unrefreshing sleep is a hallmark of chronic fatigue syndrome/myalgic encephalomyelitis (CFS). This study examined brain structure variations associated with sleep quality in patients with CFS. 38 patients with CFS (34.8 ± 10.1 years old) and 14 normal controls (NCs) (34.7 ± 8.4 years old) were recruited. All subjects completed the Hospital Anxiety and Depression Scale, Pittsburgh Sleep Quality Index (PSQI), and Chalder Fatigue Scale (CFQ) questionnaires. Brain MRI measures included global and regional grey and white matter volumes, magnetization transfer T1 weighted (MT-T1w) intensities, and T1 weighted (T1w) and T2 weighted spin echo signal intensities...
June 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28661066/sexual-dimorphism-in-hepatic-lipids-is-associated-with-the-evolution-of-metabolic-status-in-mice
#18
Ana Francisca Soares, Jonathan Paz-Montoya, Hongxia Lei, Marc Moniatte, Rolf Gruetter
Ectopic lipid accumulation in the liver is implicated in metabolic disease in an age- and sex-dependent manner. The role of hepatic lipids has been well established within the scope of metabolic insults in mice, but has been insufficiently characterized under standard housing conditions, where age-related metabolic alterations are known to occur. We studied a total of 10 male and 10 female mice longitudinally. At 3, 7 and 11 months of age, non-invasive (1) H-magnetic resonance spectroscopy ((1) H-MRS) was used to monitor hepatic lipid content (HLC) and fatty acid composition in vivo, and glucose homeostasis was assessed with glucose and insulin challenges...
June 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28654718/building-connectomes-using-diffusion-mri-why-how-and-but
#19
Stamatios N Sotiropoulos, Andrew Zalesky
Why has diffusion MRI become a principal modality for mapping connectomes in vivo? How do different image acquisition parameters, fiber tracking algorithms and other methodological choices affect connectome estimation? What are the main factors that dictate the success and failure of connectome reconstruction? These are some of the key questions that we aim to address in this review. We provide an overview of the key methods that can be used to estimate the nodes and edges of macroscale connectomes, and we discuss open problems and inherent limitations...
June 27, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28643891/direct-comparison-of-high-temporal-resolution-cine-mri-with-doppler-ultrasound-for-assessment-of-diastolic-dysfunction-in-mice
#20
Thomas A Roberts, Anthony N Price, Laurence H Jackson, Valerie Taylor, Anna L David, Mark F Lythgoe, Daniel J Stuckey
Diastolic dysfunction is a sensitive early indicator of heart failure and can provide additional data to conventional measures of systolic function. Transmitral Doppler ultrasound, which measures the one-dimensional flow of blood through the mitral valve, is currently the preferred method for the measurement of diastolic function, but the measurement of the left ventricular volume changes using high-temporal-resolution cinematic magnetic resonance imaging (CINE MRI) is an alternative approach which is emerging as a potentially more robust and user-independent technique...
June 23, 2017: NMR in Biomedicine
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