GABA Editing at 3T with Macromolecule Suppression:  MEGA-SPECIAL
Jamie Near¹, Philip J. Cowen¹, Peter Jezzard^2
1Department of Psychiatry, University of Oxford, Oxford, OXON, United Kingdom; ²The Centre for Functional Magnetic Resonance Imaging of the Brain, John Radcliffe Hospital, Oxford, OXON, United Kingdom

GABA editing using the MEGA-PRESS technique at 3T results in signal contamination from macromolecules.  We present a modified spectral editing technique called MEGA-SPECIAL, which enables the use of longer, more frequency-selective editing pulses.  This, in turn, enables the use of previously described strategies for the removal of macromolecular contamination.  In-vitro measurements indicate that the newly developed sequence provides improved editing efficiency over MEGA-PRESS, and experiments performed in-vivo confirm that macromolecular suppression is achieved.

¹³C MRS of Frontal Lobe at 3 Tesla  Using a Volume Coil for Stochastic Proton Decoupling
Shizhe Steve Li¹, Yang Zhang¹, Shumin Wang¹, Maria Ferraris Araneta¹, Christopher S. Johnson¹, Yun Xiang¹, Robert B. Innis¹, Jun Shen^1
1National Institutes of Health, Bethesda, MD, United States

¹³C spectra from the frontal lobe of human brain were acquired for the first time at 3 Tesla. After intravenous infusion of [2-¹³C]glucose, glutamate, glutamine, and aspartate were detected in the carboxylic/amide carbons region. The RF power deposition was well below the safety guidelines, due to enhanced decoupling efficiency from the volume coil and weak J coupling between proton and carboxylic/amide carbons. The effect of the strong B₀ field inhomogeneity in the frontal lobe region was reduced by RF coil arrangement and by a reference deconvolution technique that used the glutamate C5 peak as a lineshape reference.

In Vivo detection of trans-Fatty Acids by ¹³C MRS at 7T
Ivan Dimitrov^1,2, Jimin Ren², Deborah Douglas², A Dean Sherry², Craig R. Malloy^2
1Philips Medical Systems, Cleveland, OH, United States; ²Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States

The severe health implications of trans-fats are well-known: their consumption leads to coronary heart disease, diabetes, cancer, liver dysfunction, and Alzheimer’s. We report the first non-invasive detection of trans-fats in humans by ¹³C MRS at 7T. WALTZ-16 decoupled FIDs with NOE were acquired from calves of healthy volunteers in 5 min. The allylic carbons (α to C=C) display substantially different chemical shifts (cis 27.18 vs. trans 32.59 ppm). A volunteer on a Western diet had a trans : cis ratio = 4.4 %, consistent with ex vivo reports, whereas no trans-fats were detected in a volunteer on a Mediterranean diet.

Stimulated-Echo Contrast with Hyperpolarized [1-¹³C]-Pyruvate
Peder E. Z. Larson¹, Ralph Hurd², Adam B. Kerr³, Robert Bok¹, John Kurhanewicz¹, Daniel B. Vigneron^1
1Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, CA, United States; ²Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States; ³Electrical Engineering, Stanford University, Stanford, CA, United States

Stimulated-echoes can be used to provide high sensitivity to diffusion and flow, providing unique contrast.  We have developed and applied stimulated-echo pulse sequences for hyperpolarized 13C metabolic imaging, studying both normal animals and the TRAMP prostate cancer mouse model to better distinguish the local metabolite environment.  These experiments demonstrated a dramatic increase in CNR for tumors and present a new parameter for characterizing the metabolic state.

Rapid Volumetric Imaging of Cardiac Metabolism
Angus Z. Lau^1,2, Albert P. Chen³, Nilesh Ghugre², Venkat Ramanan², Wilfred W. Lam², Kim A. Connelly⁴, Graham A. Wright^1,2, Charles H. Cunningham^1,2
1Dept. of Medical Biophysics, University of Toronto, Toronto, ON, Canada; ²Imaging Research, Sunnybrook Health Sciences Centre, Toronto, ON, Canada; ³GE Healthcare, Toronto, ON, Canada; ⁴Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael’s Hospital and University of Toronto, Toronto, ON, Canada

A rapid multi-slice cardiac-gated spiral ¹³C imaging pulse sequence consisting of a large flip-angle spectral-spatial excitation RF pulse with a single-shot spiral k-space trajectory was implemented and demonstrated in vivo. This sequence allows for whole heart coverage (6 slices, 8.8 mm in-plane resolution) in any plane, with imaging of the metabolites of interest, [1-¹³C] pyruvate, [1-¹³C] lactate, and ¹³C bicarbonate, within a single 20 s breathhold. The sequence is anticipated to be useful in the non-invasive monitoring of changes in spatial distribution of metabolites in disease.

High Resolution ³¹P Magnetic Resonance Spectroscopic Imaging of the Human Brain at 7T
Jannie Petra Wijnen¹, Arend Heerschap¹, Tom W.J. Scheenen^1,2
1Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, Gelderland, Netherlands; ²Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany

We demonstrated the use of a surface ³¹P quadrature coil in combination with a ¹H CP head coil for ³¹P MRSI of the brain at 7T with high sensitivity and spatial resolution. ³¹P MRS was run with a pulse acquire MRSI sequence with adiabatic excitation. With this method we detected phosphorylated signals from the energy metabolism in the brain as well as resonances from phosphomono and diester compounds and inorganic phosphate in the human brain within relatively short acquisition times (16 or 25minutes).

Diffusion-Weighted Spectroscopy in the Healthy and U87 Glioblastoma-Induced Mouse Brain - not available
Julien Valette^1,2, Boucif Djemai², Françoise Geffroy², Mohamed Ahmed Ghaly², Fawzi Boumezbeur², Denis Le Bihan², Franck Lethimonnier^2
1CEA-MIRCen, Fontenay-aux-Roses, France; ²CEA-NeuroSpin, Gif-sur-Yvette, France

Diffusion-weighted (DW) spectroscopy is a unique tool for probing the intracellular compartment in vivo. As far as we know, the apparent diffusion coefficient (ADC) of metabolites has never been reported in the mouse brain. In this preliminary work, the ADC of six metabolites is measured in a mouse brain for the first time, using an original DW-LASER sequence. In addition, measurements are performed in a Human U87-MG glioblastoma induced in the same animal, showing a dramatic increase in the ADC of choline compounds, which might be ascribed to lactacidosis-induced cell swelling.

Real Time Measurement and Correction of Motion-Induced Changes in B0 Field for Neuro Spectroscopic Imaging
Aaron Timothy Hess¹, Ovidiu C. Andronesi^2,3, Matthew Dylan Tisdall^2,3, Ernesta M. Meintjes^1,4, Andre J. van der Kouwe^2,3
1University of Cape Town, Cape Town, South Africa; ²Martinos Center for Biomedical Imaging, Massachusetts General Hospital, MA, United States; ³Department of Radiology, Harvard Medical School, MA, United States; ⁴MRC/UCT Medical Imaging Research Unit

Real time measurement of the B0 field using an EPI navigator is presented, its use in real time first order shim correction for LASER spectroscopic imaging is demonstrated. Homogeneity of the B0 field is important in spectroscopy and spectroscopic imaging and thus, by measuring the B0 field in real time, changes to the linear shim gradients and frequency offset are corrected on the fly. This technique is shown to minimise line broadening due to motion induced B0 changes.

Accelerated ¹H Chemical Shift Imaging of the Brain Using Compressive Sensing
Sairam Geethanath¹, Hyeonman Baek², Vikram D. Kodibagkar^1,2
1Biomedical Engineering, UT Southwestern Medical Center at Dallas, Dallas, TX, United States; ²Dept of Radiology, UT Southwestern Medical Center at Dallas, Dallas, TX, United States

Application of compressed sensing to 1H Chemical Shift Imaging (CSI) of in vivo human brain data has been performed for the first time. The CSI data is sparse in the wavelet domain along the spatial and temporal dimensions and hence can be reconstructed with high SNR from significantly undersampled k-space. This provides a significant reduction in acquisition time which is highly desired for CSI. The metabolite maps generated for 3 major metabolites of N-acetylaspartate, Creatine and Choline from 20% of the original k-space data match closely with the corresponding metabolite maps generated for the original k-space.

In Vivo L-COSY MR Distinguishes Glutamate from Glutamine and  Shows Neuropathic Pain to Cause a Buildup of Glutamine in the Brain
Alexander Peter Lin¹, Saadallah Ramadan¹, Peter Stanwell¹, Tuan Luu¹, James Celestin², Zahid Bajwa², Carolyn Mountford^1
1Center for Clinical Spectroscopy, Brigham and Women's Hospital, Boston, MA, United States; ²Pain Management Center, Beth Israel Deaconess Medical Center, Boston, MA, United States

This study utilizes two-dimensional (2D)  COrrelated SpectroscopY (COSY) to allow, in a clinically accepted time, detailed chemical information to be collected in situ from the brain.  2D COSY can in theory separate the glutamate and glutamine resonances by measuring distinct  scalar coupling.  These metabolites are neurotransmitters and  affected by a number of diseases.  For the first time we successfully distinguished between  glutamine and glutamate using 2D COSY and show that glutamine is present  in higher quantities  in subjects with neuropathic pain.