Dana Goerzen^1,2, Tiffany Bell^3,4,5, Jamie Near^1,2, and Ashley D Harris^3,4,5
1McGill University, Montreal, QC, Canada, ²Centre d'Imagerie Cérébrale, Douglas Mental Health University Institute, Montreal, QC, Canada, ³Radiology, University of Calgary, Calgary, AB, Canada, ⁴Hotchkiss Brain Institution, Calgary, AB, Canada, ⁵Alberta Children's Hospital Research Institute, Calgary, AB, Canada

A key challenge in magnetic resonance spectroscopy in the human brain is assessing the reliability of metabolite concentration estimates, since the ground truth is generally unknown. This project assesses the correlations between 3T MRS metabolite measures  against two “gold standard” 7T sequences as a means to assess which 3T sequences are the most reliable at detecting common metabolites of interest. This work will help researchers to make informed choices about which sequences to use for optimal detection of their metabolites of interest.

Guglielmo Genovese¹, Dinesh K. Deelchand¹, Melissa Terpstra¹, and Malgorzata Marjanska^1
1Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, Minneapolis, MN, United States

The goal of this abstract was to deepen the knowledge on the influence of LCModel fitting parameters and SNR on GABA quantification and on the sensitivity for detecting differences in GABA levels. To this aim, GABA concentrations were quantified using different LCModel approaches and different number of averages in synthetically altered spectra generated by adding synthetic GABA signal to in-vivo ultra-short TE, 7-T human spectra.

Philipp Lazen¹, Sahar Nassirpour², Paul Chang², Lukas Hingerl¹, Karl Rössler³, Siegfried Trattnig^1,4, Wolfgang Bogner¹, and Gilbert Hangel^1,3
1Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, ²MR Shim GmbH, Reutlingen, Germany, ³Department of Neurosurgery, Medical University of Vienna, Vienna, Austria, ⁴Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria

A 24-channel array of local shim coils in a 7 T Siemens Terra Fit was tested on eight healthy volunteers. Significant improvements of the homogeneity of the static magnetic field could be achieved and were qualitatively shown and quantitatively analyzed. The standard deviation of the resonance frequency decreased from 42.5 Hz for the standard shim (up to second order spherical harmonics) to 34.5 Hz for the 24-channel local shim array. The full width at half maximum and the signal to noise ratio also improved with the better shim. Lastly, some preliminary MRSI results could be gathered.

Hideto Kuribayashi¹, Yuta Urushibata¹, Thuy Ha Duy Dinh², Hirohiko Imai³, Sinyeob Ahn⁴, Ravi Teja Seethamraju⁵, Tadashi Isa², and Tomohisa Okada^2
1Siemens Healthcare K.K., Tokyo, Japan, ²Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan, ³Kyoto University Graduate School of Informatics, Kyoto, Japan, ⁴Siemens Medical Solutions, Berkeley, CA, United States, ⁵Siemens Medical Solutions, Boston, MA, United States

Single voxel MRS pulse sequences of semi-LASER and short-TE STEAM were compared for cerebral glucose quantification via detecting H1-α-glucose peak at 5.23 ppm.  Young healthy non-fasted subjects were scanned on a whole-body 7T MRI.  Spectra were analyzed on LCModel and in-house MATLAB software.  Semi-LASER (32-ms TE) detected the H1-α-glucose peak at posterior cingulate cortex (27-mL volume) with higher SNR (9.1 vs 5.1) than short-TE STEAM (5-ms TE) in shorter scan time (11 vs. 12.5 minutes), respectively, and estimated glucose concentration to be 1.26 mM.  More robust water suppression techniques are required to stabilize baselines around the peak.

Daniel Spielman¹, Phil Adamson², Ralph Hurd¹, Meng Gu¹, Kirk Riemer³, Ryan Beckman³, Michael Ma³, Kenichi Okamura³, and Frank Hanley^3
1Radiology, Stanford University, Stanford, CA, United States, ²Electrical Engineering, Stanford University, Stanford, CA, United States, ³Cardiothoracic Surgery, Stanford University, Stanford, CA, United States

We used single-voxel ¹H MRS at 3T to study acute brain metabolic changes during cardiopulmonary bypass (CPB) surgery in a neonatal piglet model, with the overall goal of  determining optimal surgical parameters for minimizing brain injury. The recent improvements in proton spectroscopy and MR scanner performance allowed robust measurement of dynamic brain water and metabolic changes during hypothermia and circulatory arrest. Key findings include a linear relationship between unsuppressed water and brain temperature, observation of the theoretically predicted NMR “powder pattern” from intravascular water during hypoxia, and quantitative measurements of glucose, lactate, and phosphocreatine metabolic rates vs temperature.

Tiffany Bell^1,2,3, Mehak Stokoe^1,2,3, and Ashley Harris^1,2,3
1Department of Radiology, University of Calgary, Calgary, AB, Canada, ²Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada, ³Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada

Studies have shown that GABA+ increases with age during development, however roughly 50% of this signal reflects macromolecules. It is often assumed that macromolecule levels are stable, but there has been no attempt to directly validate this in youth. Here, we use a sequence specifically designed to suppress the macromolecule signal that contaminates the measured GABA+ signal when using MEGA-PRESS. We show no relationship between macromolecule-suppressed GABA and age in youth aged 7-14 years. We suggest increases in macromolecule levels may drive previously shown relationships between age and GABA+ levels, highlighting the importance of controlling for macromolecules in MRS analyses.  

Parker L La¹, Robyn Walker¹, Julie M Joyce¹, Tiffany Bell¹, William Craig², Quynh Doan³, Miriam Beauchamp⁴, Roger Zemek⁵, Pediatric Emergency Research Canada (PERC)⁶, Keith O Yeates⁷, and Ashley D Harris^1
1Radiology, University of Calgary, Calgary, AB, Canada, ²Pediatrics, University of Alberta and Stollery Children's Hospital, Edmonton, AB, Canada, ³Pediatrics, University of British Columbia, Vancouver, BC, Canada, ⁴Psychology, University of Montreal and St Justine Hospital, Montreal, QC, Canada, ⁵Pediatrics and Emergency Medicine, University of Ottawa and Children's Hospital of Eastern Ontario, Ottawa, ON, Canada, ⁶Alberta Children's Hospital, Calgary, AB, Canada, ⁷Psychology, University of Calgary, Calgary, AB, Canada

Disruptions in brain metabolites following concussion are commonly reported in the literature. These studies often have different timings following injury, are limited to adults and have limited sample size. Using magnetic resonance spectroscopy (MRS), we show in the largest MRS in pediatric concussion study to date, that there are no group differences in metabolites between concussion and orthopedic injury at acute injury. Glx was associated with cognitive symptoms but no other metabolites showed a relationship with symptoms. No difference between groups may indicate that metabolic disturbance following injury may be a broad indicator of injury or alterations are regionally specific.

Peter Bulanov¹, Andrei Manzhurtsev^1,2, Petr Menshchikov^3,4, Maxim Ublinskiy^2,3, Ilya Melnikov², Natalia Semenova^1,2,3,5, and Tolib Akhadov^2
1Lomonosov Moscow State University, Moscow, Russian Federation, ²Clinical and Research Institute of Emergency Pediatric Surgery and Traumatology, Moscow, Russian Federation, ³Emanuel Institute of Biochemical Physics of RAS, Moscow, Russian Federation, ⁴PHilips Healthcare, Russia, Moscow, Russian Federation, ⁵Semenov Institute of Chemical Physics of the Russian Academy of Sciences, Moscow, Russian Federation

The effect of mild traumatic brain injury (mTBI) on the values of the cerebral pH in the region of the posterior cingulate cortex was studied. pH was determined by analyzing the chemical shifts of mobile protons in the aromatic region of the spectrum of histidine, homocarnosine, resonating at ~7-8 ppm in PRESS spectra. According to our data, the pH value decreases by ~1% in posterior cingulate cortex after acute mTBI.

Katherine Breedlove¹, David R Howell², Inga K Koerte^3,4, Eduardo Coello⁴, Molly Charney⁴, Huijin Liao⁴, Corey Lanois⁵, and Alexander Lin^4
1Radiology, Brigham and Women's Hospital, Boston, MA, United States, ²Childrens Hospital Colorado, Aurora, CO, United States, ³Ludwig-Maximilians-Universitat, Munich, Germany, ⁴Brigham and Women's Hospital, Boston, MA, United States, ⁵Boston Children's Hospital, Boston, MA, United States

A population of collegiate athletes was evaluated post-concussion for neurometabolic levels in the PCG by magnetic resonance spectroscopy (MRS) and Post-Concussion Symptom Scale (PCSS) following injury.  Evaluations were conducted within 72 hours of diagnosed concussion with a follow-up two months after injury.  Correlations between neurometabolic concentration and PCSS composite scores were explored.  For the purpose of this work, focus was given to the concentrations and concentration ratios of total NAA (NAA+NAAG), total Glutamate (Glu+Gln), and Glutamate (Glu).  The change in metabolites between the two time points was also computed.  

Matthew Rogan^1,2,3, Joseph B R Smith^1,2,3, Alexander Friend^3,4, Jamie H Macdonald^3,4, Sam J Oliver^3,4, Gabriella M K Rossetti⁵, Mark Mikkelsen^6,7, Richard A E Edden^6,7, and Paul G Mullins^1,2,3
1School of Psychology, Bangor University, Bangor, United Kingdom, ²The Bangor Imaging Unit, Bangor University, Bangor, United Kingdom, ³The Extremes Research Group, Bangor University, Bangor, United Kingdom, ⁴School of Sport Health and Exercise Sciences, Bangor University, Bangor, United Kingdom, ⁵Centre for Integrative Neuroscience and Neurodynamics, University of Reading, Reading, United Kingdom, ⁶Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁷F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States

Our group has previously shown that exposure to environmental hypoxia reduces regional CBF within the posterior nodes of the default mode network. Within the same region, hypoxia also reversed the task evoked BOLD response. However, it is unclear what neurometabolic signals underlie this peculiar hemodynamic response to hypoxia. To investigate we employed event related functional MRS to measure the dynamic changes in neurometabolites within the posterior cingulate during hypoxia. We found that hypoxia negates the functional increase in glutamate as seen in normoxia, and induced a regional reduction in glucose. This observation suggests that hypoxia may reduce regional oxidative metabolism. 

Nathalie Just¹, Pierre-Marie Chevillard¹, and Martine Migaud^1
1NhyRVana, INRAE, Nouzilly, France

A proton MR Spectroscopy investigation of the sheep hypothalamus at 3T was proposed to compare the impact of photoperiodism on neurochemical profiles. Results showed transient metabolic changes as a function of time and significant differences between long days (LD) and short days (SD) demonstrating photoperiodic regulation of the metabolism of the hypothalamus.

Martin Gajdošík^1,2, Karl Landheer¹, Kelley M. Swanberg¹, Fatemeh Adlparvar², Guillaume Madelin², Wolfgang Bogner³, Christoph Juchem^1,4, and Ivan I. Kirov^2,5,6
1Department of Biomedical Engineering, Columbia University, New York City, NY, United States, ²Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York City, NY, United States, ³High-Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria, ⁴Department of Radiology, Columbia University Medical Center, New York City, NY, United States, ⁵Department of Neurology, New York University Grossman School of Medicine, New York City, NY, United States, ⁶Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University Grossman School of Medicine, New York City, NY, United States

The hippocampus is one of the most challenging brain regions for proton MR spectroscopy (MRS) applications. Moreover, quantification of J-coupled species such as myo-inositol (m-Ins) and glutamate + glutamine (Glx) is affected by the presence of macromolecular background. Here we investigate the feasibility of reproducibly measuring their concentrations at long T_E of 120 ms, using sLASER localization.

Dunja Simicic^1,2,3, Katarzyna Pierzchala^1,2, Olivier Braissant⁴, Stefanita-Octavian Mitrea^1,2, Dario Sessa⁵, Valerie McLin⁵, and Cristina Cudalbu^1,2
1CIBM Center for Biomedical Imaging, Lausanne, Switzerland, ²Animal Imaging and Technology, EPFL, Lausanne, Switzerland, ³Laboratory of Fuctional and Metabolic Imaging, EPFL, Lausanne, Switzerland, ⁴Service of Clinical Chemistry, University of Lausanne and University Hospital of Lausanne, Lausanne, Switzerland, ⁵Swiss Center for Liver Disease in Children, University Hospitals Geneva, Geneva, Switzerland

Type-C hepatic encephalopathy (CHE) is a complication of chronic liver disease (CLD). It is known that children are more affected by CLD than adult patients. Bile duct ligated rat (BDL) is a model of CLD-induced CHE. It was shown that rats having acquired CLD as pups display more profound neurometabolic disturbances than adults. Cr-treatment showed a positive effect in youngP21 BDL-rats resulting in less pronounced metabolic changes. Our aim was to test whether Cr-supplementation dampens the changes observed in CHE in a longitudinal model of CLD acquired in early childhood-P15 and if these changes are similar to those in P21-rats.

Peter Adany¹, In-Young Choi^1,2, and Phil Lee^1,3
1Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, KS, United States, ²Department of Neurology, University of Kansas Medical Center, Kansas City, KS, United States, ³Department of Radiology, University of Kansas Medical Center, Kansas City, KS, United States

The availability of robust lipid signal removal methods for whole slab MRSI opens up the possibility to measure signals from the edge of the brain, including cortical regions. We have developed a Fast LIpid signal Processing (FLIP) algorithm that effectively removes subcutaneous lipid signals. Recently, we have further developed our FLIP method to include a novel multi-scale auto-alignment feature at a sub-millimeter scale. This study demonstrates that the new alignment algorithm enables the detection of subtle displacement of subject head positions between scans and significantly improves the performance of lipid removal in full-FOV MRSI.

Layla Tabea Riemann¹, Christoph Stefan Aigner¹, Ralf Mekle², Sebastian Schmitter¹, Bernd Ittermann¹, and Ariane Fillmer^1
1Physikalisch-Technische Bundesanstalt (PTB), Braunschweig und Berlin, Germany, ²Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany

This work assesses the test-retest repeatability and reproducibility of spectral shapes and neurochemical profiles of the SPECIAL ¹H MR spectroscopy sequence employing three different adiabatic pulses in-vivo at 7T: the standard hyperbolic secant pulse and two gradient-modulated pulses, namely a GOIA and a WURST pulse. Nine healthy volunteers were scanned four times each, with all three SPECIAL variants to establish three different repeatability or reproducibility measures and to evaluate the limits in the precision of the resulting metabolite quantification. 

Rajakumar Nagarajan¹, Anant Shinde^2,3, Muhammed Enes Gunduz^2,3, and Gottfried Schlaug^2,3
1Human Magnetic Resonance Center, Institute for Applied Life Sciences, University of Massachusetts Amherst, Amherst, MA, United States, ²Biomedical Engineering, University of Massachusetts Amherst, Amherst, MA, United States, ³Baystate Medical Center, University of Massachusetts Medical School, Springfield, MA, United States

We studied the effects of motor region tDCS on metabolite levels in a spectroscopic voxel with repeated episodes of 5min of constant current dose levels anticipating stimulation-induced alterations in metabolite concentration at rest. The cumulative change in GABA from before the first tDCS stimulation epoch to after the last epoch showed a significant polarity effect. The first tDCS epoch revealed polarity dependent opposite trends in GABA and Glx from baseline (before stimulation) to post-stimulation. This study provides insights into how tDCS leads to polarity dependent modulation of cerebral metabolites and might provide a model for future MRS stimulation studies. 

Alexey Yakovlev^1,2,3, Andrei Manzhurtsev^1,3, Petr Menshchikov^3,4, Maxim Ublinskiy³, Tolib Akhadov¹, and Natalia Semenova^1,2,3
1Clinical and Research Institute of Emergency Pediatric Surgery and Trauma, Moscow, Russian Federation, ²N.N.Semenov Federal research center of Chemical Physics Russian Academy of Sciences, Moscow, Russian Federation, ³N.M. Emanuel Institute of Biochemical Physics RAS, Moscow, Russian Federation, ⁴Philips Healthcare, Moscow, Russian Federation

Changes in the concentration of neurotransmitters in response to a short (or event-related) stimulus in not well investigated. Due to low neurotransmitter cycle rates, these changes can be related to  neurotransmitter release from vesicles. In this work, we measured a time course of Glx level in response to a short visual stimulus in a period exceeding the BOLD response using 3T MR scanner. This Glx level dynamic is considered as the release of Glu from the vesicles, reuptake, and refilling. For the first time, we investigated the dynamics of the BOLD-effect using the metabolic signal.

Alexandra Lipka^1,2, Eva Heckova¹, Assunta Dal-Bianco³, Gilbert Hangel¹, Bernhard Strasser¹, Stanislav Motyka¹, Lukas Hingerl¹, Paulus Rommer³, Fritz Leutmezer³, Petra Hnilicová⁴, Ema Kantorová⁴, Stephan Gruber¹, Siegfried Trattnig^1,2, and Wolfgang Bogner^1,2
1High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, ²Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria, ³Department of Neurology, Medical University of Vienna, Vienna, Austria, ⁴Jessenius Faculty of Medicine in Martin, Comenius University, Bratislava, Slovakia

Routine T1/T2-weighted magnetic resonance imaging (MRI) is the method of choice for diagnosis and treatment monitoring of Multiple Sclerosis (MS), but is not being able to map the underlying pathological processes. In contrast to T1/T2-lesions which represent the general macroscopic tissue damage, MR Spectroscopic Imaging (MRSI) can detect pathologies on a biochemical level. In 54 relapsing-remitting (RRMS) patients and 16 healthy age/sex-matched controls, we show - enabled through ultra-high resolution Free Induction Decay(FID)-MRSI at 7T - the metabolic distribution within lesions and their close proximity as well as the importance of myo-Inositol as an imaging biomarker in early lesion development.

Alexandra Lipka^1,2, Wolfgang Bogner^1,2, Assunta Dal-Bianco³, Gilbert Hangel¹, Bernhard Strasser¹, Stanislav Motyka¹, Lukas Hingerl¹, Paulus Rommer³, Fritz Leutmezer³, Stephan Gruber¹, Siegfried Trattnig^1,2, and Eva Heckova^1
1High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, ²Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria, ³Department of Neurology, Medical University of Vienna, Vienna, Austria

Conventional T1/T2-weighted magnetic resonance imaging (MRI) is the method of choice for diagnosis and treatment monitoring of Multiple Sclerosis (MS). Susceptibility weighted imaging (SWI) provides additional information about iron deposition. In addition to these imaging modalities, MR Spectroscopic Imaging (MRSI) can detect pathologies on a biochemical level. In 32 relapsing remitting (RRMS) patients, we showed - with ultra-high spatial resolution Free Induction Decay(FID)-MRSI at 7T - the metabolic changes associated with different types of iron accumulation and the metabolic gradient spanning from within the lesion to its close proximity.

Wufan Zhao¹, Eduardo Coello¹, Marcia Sahaya Louis¹, Katherine Breedlove¹, Assaf Tal², and Alexander Lin^1
1Radiology, Brigham and Women's Hospital, Boston, MA, United States, ²Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel

This work introduces a novel way to analyze MR spectroscopic imaging scans by characterizing grey matter and white matter tissue types based on their contributions to metabolite concentrations. This method extracts grey matter and white matter components from anatomical images after tissue segmentation and correlates them with relative metabolite concentrations. The value of the method is shown in visualizing different metabolic profiles for grey and white matter and establishing ranges of metabolite contribution.