MRS & Other

Thursday 15 May 2014

Jack Tristan Pearson¹, Steven Reynolds², Adriana Bucur², Allan Pacey¹, and Martyn Paley^2
1Human Metabolism, The University of Sheffield, Sheffield, South Yorkshire, United Kingdom, ²Cardiovascular Science, The University of Sheffield, Sheffield, South Yorkshire, United Kingdom

Approximately 25% of males have poor semen quality and diagnosis of male infertility relies on techniques developed in the 1950’s. To investigate sperm metabolism, HR MAS NMR of boar sperm was performed at two incubation temperatures and in the presence or absence of α-chlorohydrin (an inhibitor of glycolysis). HR MAS successfully identified significant increases in acetate, glutamine and glucose at increased incubation temperatures. A significant decrease in lactate was identified when metabolism was inhibited with α-chlorohydrin. This data supports the potential use for HR MAS in identification of metabolic biomarkers in sperm and for infertility diagnosis in the clinical setting.

Rama Jayasundar¹, Somenath Ghatak¹, Prashant K Rai¹, and Gaurav Sharma^1
1Department of NMR, All India Institute of Medical Sciences, New Delhi, Delhi, India

With growing importance of nutrition in healthcare, NMR can be used to obtain metabolosensory signatures related to food. In this context, organoleptic property of 23 nutraceuticals (13 sweet, 10 pungent) has been analysed with proton NMR and correlated with objective taste measurements using Electronic Tongue. Similar classification was arrived at independently by PCA analysis of data from NMR and Etongue. Potential spectral markers such as sucrose (sweet) and non-sweet amino acids like valine and isoleucine (pungent) could provide NMR sensory descriptors. With increasing interest in nutritional therapeutics, NMR based chemosensory signatures could open new vistas of application in nutritional healthcare.

Hetty Prinsen¹, Cosimo Giannini², Robin A de Graaf¹, Nicola Santoro¹, Christoph Juchem¹, Sonia Caprio¹, and Raimund I Herzog^1
1Yale University, New Haven, CT, United States, ²University of Chieti, Chieti, Italy

The prevalence of obesity has increased to epidemic levels, not only in adults, but also in children. Obesity has been associated with the development of insulin resistance, progression to type 2 diabetes, development of fatty liver, and progression to liver cirrhosis. We are still in need for sensitive biomarkers that allow identification of the particularly at risk individuals amenable to early and intensive interventions. Here we correlate clinical markers of obesity-related complications with plasma metabolite levels in obese insulin-sensitive and insulin-resistant youth, using a novel workflow for acquisition and processing of metabolomic ¹H NMR data.

Veronika Rackayová¹, Olivier Braissant², Valérie A. McLin³, and Cristina Cudalbu^4
1Laboratory for Functional and Metabolic Imaging, Center for Biomedical Imaging, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Vaud, Switzerland, ²Laboratoire de Chimie Clinique, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Vaud, Switzerland, ³Swiss Center for Liver Disease in Children, Department of Pediatrics, University Hospitals Geneva, Geneva, Switzerland, ⁴Centre d’Imagerie Biomedicale (CIBM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Vaud, Switzerland

Chronic liver disease affects both adults and children and is often associated with some degree of hepatic encephalopathy (HE). In childhood, acute hyperammonemia (HA) is associated with brain edema and leads to irreversible damage of the developing central nervous system (CNS). Although cognitive deficits exist in children with CLD, the underlying mechanism is unclear [2]. How the developing brain responds to the metabolic changes of CLD, and how these mechanisms differ from those in adult patients are two unknowns. We hypothesized that blood-brain-barrier permeability and energy metabolism may be different in adult and developing brain.

Nathalie Just¹, Carola Jaquelina Romero², and Rolf Gruetter^1,3
1CIBM-AIT, EPFL, Lausanne, Switzerland, ²Laboratory for functional and metabolic Imaging, EPFL, Lausanne, Switzerland, ³Departments of Radiology, University of Lausanne and University of Geneva, Lausanne and Geneva, Switzerland

To date the metabolic mechanisms of regulation of the barrel cortex by thalamocortical transmissions remain unclear. In the present work, the neurochemical profiles of the barrel cortex and thalamus were measured using functional MRS during 32-minute periods of rest and trigeminal nerve stimulation. Significant changes in Lactate and Glutamate were estimated in both structures during stimulation. In addition, GABA and Glutamate levels were correlated within or between each structure. GABA levels in the thalamus were linearly correlated to GABA levels in S1BF during activation. Upon validation, these results should contribute to the accurate interpretation of functional neuroimaging signals.

Hannes M. Wiesner¹, Wei Luo², Qing X. Yang³, Xiao-Hong Zhu¹, Scott Schillak¹, and Wei Chen^1
1Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States,²Department of Engineering Science and Mechanics, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States, ³Center for NMR Research, Department of Radiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States

In vivo MRS and MRI can benefit significantly from high/ultrahigh field in improving detection sensitivity and spectral resolution. However, the RF wave property can behave substantially differently at high field and influence both B₁⁺ and B₁^- fields, thus, affect the transmission and reception efficiencies as well as RF power transmission and SAR. This study aims to quantitatively investigate and compare the transmission and reception efficiencies of ¹H and common X-nuclei ³¹P, ²³Na and ¹⁷O at 7T. The results indicate that low- nuclei require a large RF pulse voltage (or power) to achieve the same flip angle as compared to ¹H spin, nevertheless, their relative RF power demand is significantly reduced due to a higher B₁⁺ transmission efficiency at high field. Moreover, low- nuclei exhibit much better reception efficiencies than that of ¹H, leading to superior detection sensitivity at high/ultrahigh field.

Wybe JM van der Kemp¹, Vincent O Boer¹, Peter R Luijten¹, and Dennis WJ Klomp^1
1Radiology, UMC Utrecht, Utrecht, Netherlands

The SNR per time unit of the signals of heteronuclear J-coupled 31P metabolites can be increased by using an adiabatic multi-echo polarization transfer technique with an even number of 180 refocusing pulses on the 31P channel combined with an adiabatic multi-echo direct detection sequence in one TR, without adversely affecting the polarization transfer or the direct detection signal. The in vivo increase in SNR for phosphomonoesters as compared to low flip Ernst angle excitation pulse acquire can be up to 370%.

Hyungseok Jang¹, Sankaran Subramanian², Nallathamby Devasahayam², Shingo Matsumoto², Keita Saito², Jiachen Zhuo³, Murali C. Krishna², and Alan B. McMillan^1
1Radiology, University of Wisconsin, Madison, WI, United States, ²Radiation Biology Branch, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, MD, United States, ³Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, United States

Electron Paramagnetic Resonance Imaging (EPRI) has emerged as a promising imaging modality that is capable of imaging in vivo tissue oxygenation. Recently, single acquisition EPRI using gridding and k-space extrapolation (KSE) has been proposed to improve temporal resolution of single-point (SP) imaging acquisitions by 3x. However, SP-EPRI is still limited in temporal and spatial resolution. In this work, we have developed new methods for accelerated SP imaging by combining a new, bilateral KSE technique with model-based compressed sensing.

Milan Scheidegger^1,2, Alexander Fuchs¹, and Anke Henning^1,3
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Zurich, Switzerland, ²Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Zurich, Switzerland, ³Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Würtemberg, Germany

This work demonstrates that both accuracy and precision are important to evaluate for performance validation of spectral fitting packages as demonstrated on the example of ProFit – a spectral fitting package for 2D JPRESS. Strong regularization or tight constraints as implemented in different commercial or freely available spectral fitting routines can lead to small coefficients of variance but strong bias of the quantification results which hinder the detection of naturally occurring variance of metabolite concentrations.

Hyungseok Jang¹, Sankaran Subramanian², Nallathamby Devasahayam², Shingo Matsumoto², Keita Saito², Murali C. Krishna², and Alan B. McMillan^1
1Radiology, University of Wisconsin, Madison, WI, United States, ²Radiation Biology Branch, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, MD, United States

Electron paramagnetic resonance imaging (EPRI) has surfaced as a promising technique that can allow quantitative imaging of tissue oxygenation. Owing to the extremely short spin-spin relaxation time, single point imaging (SPI) is used, where entire FID is phase-encoded. Several methods have been proposed to overcome zoom-in effect inherent in SPI-EPRI. Among them, spin echo based SPI-EPRI (ESPI-EPRI) is worthy of study because it can allow simultaneous T₂ and T₂* estimation when combined with a single acquisition method. In this study, the physical and physiological significance of T₂ and T₂* measures was explored through the proposed single acquisition method in ESPI-EPRI.