Joint Annual Meeting ISMRM-ESMRMB 2014 10-16 May 2014 Milan, Italy

Normal Brain Physiology by MRS & Other Modalities

Tuesday 13 May 2014
Yellow 1, 2 & 3  16:00 - 18:00 Moderators: Yukio Miki, M.D., Ph.D., Jay J. Pillai, M.D.

16:00 0457.   
Milan Scheidegger1,2, Alexander Fuchs1, Simon Ametamey3,4, Felix Kuhn5, Anass Johayem5, Alfred Buck4,5, Erich Seifritz2,4, and Anke Henning1,6
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 2Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Zurich, Switzerland, 3Institute of Pharmaceutical Sciences, University and ETH Zurich, Zurich, Switzerland,4Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland, 5Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland, 6Max Planck Institute for Biological Cybernetics, Tübingen, Germany

In this multimodal, double-blind, randomized, placebo-controlled PET-MRS study in 20 healthy subjects, we report a pharmacological modulation of glutamate-dependent neuroreceptor plasticity in the pregenual anterior cingulate cortex following the administration of the NMDA-receptor antagonist ketamine. In order to investigate the functional interplay between the major excitatory neurotransmitter glutamate (Glu) and the density of the metabotropic glutamate receptor subtype 5 (mGluR5) we combined proton magnetic resonance spectroscopy (1H-MRS) with positron emission tomography (11C-ABP688-PET). Our findings complement previous reports of increased glutamate release during ketamine challenge by providing additional in vivo molecular imaging evidence for ketamine-induced neurotransmitter-receptor coupling.

16:12 0458.   
Diffusion characteristic of infused Acetate in the rat brain in vivo
Masoumeh Dehghani M.1, Bernard Lanz1, Nicolas Kunz2, Corina Mihaela Berset2, and Rolf Gruetter1,3
1Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Vaud, Switzerland, 2Center for Biomedical Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Vaud, Switzerland, 3Departments of Radiology, Universities of Lausanne and Geneva, Lausanne and Geneva, Switzerland

The aim of this study is to address the diffusion characteristic of Acetate(Ace) in the rat brain in vivo using localized diffusion weighed STEAM-based spectroscopic pulse sequence. The study design is based on the assumption that intracellular and extracellular metabolites experiences different diffusion behavior. Minimizing GABA peak contribution at 1.89 ppm in 1H MR spectra improved the accuracy of the measurement of Ace time course and the Ace diffusion in brain in vivo. The significantly larger ADC of Ace compared to intracellular metabolites suggests a substantial Ace concentration in the extracellular space of rat brain during Ace infusion.

16:24 0459.   Shorter term aerobic exercise improves brain perfusion, cognition, and cardiovascular fitness in aging
Sina Aslan1,2, Sandra Chapman2, Jeffrey Spence2, Laura DeFina3, Nyaz Didehbani2, and Hanzhang Lu4
1Advance MRI, LLC, Frisco, Texas, United States, 2Center for BrainHealth, University of Texas at Dallas, Dallas, Texas, United States, 3The Cooper Institute, Dallas, Texas, United States, 4Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States

This study adds new insights into the mounting evidence of benefits from aerobic training revealing benefits across cardiovascular fitness, cognition, and regional CBF in adults. Most studies show the gains were achieved after six months of physical training. However, the present study shows gains across three domains earlier than previously documented in sedentary middle-aged to old adults. Using pCASL MRI, we measured significant CBF gains in the anterior cingulate region which has been linked to superior cognitive-agers in late life. The findings suggest that healthy life style changes in exercise habits can help to mitigate unnecessary losses.

16:36 0460.   Longitudinal imaging of the preterm brain: white matter multi-component T2 relaxometry and MR spectroscopy
Andrew Melbourne1, Zach Eaton-Rosen1, Giles Kendall2, David Price3, Alan Bainbridge3, Ernest Cady3, Nicola J Robertson2, Neil Marlow2, and Sebastien Ourselin1
1CMIC, University College London, London, London, United Kingdom, 2Academic Neonatology, UCL Institute for Women's Health, London, United Kingdom, 3Medical Physics, University College Hospital, London, United Kingdom

This work describes longitudinal correlations in MR spectroscopy and multi-component T2 relaxometry in a group of very-preterm infants scanned at 30 and 40 weeks equivalent gestational age.

16:48 0461.   Event-related dynamics of glutamate and BOLD signal at 3 T in a repetition suppression paradigm
Dace Apšvalka1, Andrew Gadie1, and Paul Gerald Mullins1
1Psychology, Bangor University, Bangor, Gwynedd, United Kingdom

Improvements in scanner technologies and data acquisition and analysis methods allow magnetic resonance spectroscopy (MRS) techniques to detect neurochemical concentration changes associated with neural activity. This functional MRS (fMRS) technique is gaining increasing interest in neuroscience, however a debate exists as to whether stimulus related changes of metabolites might be reliably detected using fMRS, and if it is possible to do so at 3T. This study presents event related dynamics of glutamate (Glu) and blood-oxygen-level-dependent (BOLD) signal at 3T in a repetition suppression paradigm.

17:00 0462.   
Assessing Activation Induced Changes in Creatine Kinase Activity in the Human Brain using 31P Spectroscopy with Magnetisation Transfer
Chen Chen1, Penny Gowland1, Susan Francis1, Mary Stephenson1, Peter Morris1, and Andrew Peters1
1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom

31P magnetic spectroscopy with magnetisation transfer was used to investigate changes in creatine kinase (CK) kinetics induced in human visual cortex during visual stimulation by measuring the unidirectional PCr->ATP rate constant (k1). Results revealed that 1) intrinsic and apparent spin-lattice relaxation time T1 of PCr at 3T are 4.67±0.91s and 1.51±0.18s, respectively; 2) k1 increased by 17± 12 % during visual stimulation, indicating that CK turnover is elevated during increased neuronal activity.

17:12 0463.   
GABA, glutamate and intellectual ability
Anouk Marsman1, Rene C.W. Mandl1, Dennis W.J. Klomp2, Vincent O. Boer2, Anna Andreychenko3, Wiepke Cahn1, Rene S. Kahn1, Peter R. Luijten2, and Hilleke E. Hulshoff Pol1
1Psychiatry, University Medical Center Utrecht, Utrecht, Netherlands, 2Radiology, University Medical Center Utrecht, Utrecht, Netherlands,3Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands

Minimizing energy resources may be beneficial to intelligence and a combination of higher GABA and lower glutamate (Glu) levels suggest a more efficient energy use. Performing 1H-MRS at an ultra-high field strength of 7T results in increased sensitivity and spectral resolution, which are particularly important when measuring Glu and GABA. Using 7T 1H-MRS, we found that a higher Working Memory Index (an aspect of intelligence) was associated with a significantly higher GABA/Glu ratio in the occipital cortex in healthy individuals. This suggests that individuals with a higher intelligent working memory performance make more efficient use of their brains’ energy resources.

17:24 0464.   MM-suppressed GABA measurements correlate more strongly with behavior than MM-contaminated GABA+ measurements
NICOLAAS A PUTS1,2, Ashley D Harris1,2, Peter B Barker1,2, and Richard A Edden1,2
1Russell J. Morgan department of Radiology and Radiological Sciences, The Johns Hopkins University, Baltimore, Maryland, United States, 2FM Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, United States

MM-suppressed GABA concentration correlates more strongly with behavioral performance than GABA+

17:36 0465.   Changes in cerebral physiology with ageing assessed by respiratory-calibrated MRI
Michael Kelly1,2, Hannah Hare1, Michael Germuska1, Nicola Filippini1, and Daniel Bulte1
1FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, United Kingdom, 2Centre for Core Biotechnology Services, University of Leicester, Leicester, Leicestershire, United Kingdom

Recently, respiratory-calibrated MRI methods capable of providing a quantitative assessment of cerebral physiology have been developed. In this study, respiratory-calibrated MRI was applied to healthy aged subjects to investigate the effect of potentially altered baseline physiology on the parameters quantified by respiratory-calibrated MRI. The parameters were not found to correlate with physiological parameters such as age, blood pressure, BMI and pulse rate. Oxygen extraction fraction and cerebral blood flow (CBF) were found be inversely correlated and cerebrovascular reactivity and CBF were positively correlated. These findings are in agreement with recent PET studies and provide validation of respiratory-calibrated MRI methods.

17:48 0466.   Default Mode Network (DMN) Activity during Olfactory Processing
Prasanna Karunanayaka1, Megha Vasavada1, Michael Tobia1, Jianli Wang1, Paul Eslinger2, and Qing X Yang1
1Radiology, Penn State University, Hershey, Pennsylvania, United States, 2Neurology, Penn State University, Hershey, Pennsylvania, United States

Default mode Network modulations during olfactory processing can provide valuable information since both networks are implicated in higher-order cognitive processing. Network deactivation refers to a relatively higher level of neural activity during rest conditions (or low demand tasks) compared to active (or high-demand) conditions. Using olfactory fMRI, we provide direct evidence to 1) support DMN deactivation during odor stimulation and 2) establish a functional connection between olfactory and DMN networks to suggest a role for higher-order cognitive processing for olfaction.