Traditional Posters
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Traditional Poster MRS/MRSI Aquisition Exhibition Hall 1271-1304 Monday 8:15 - 10:15 Metabolite cycled density-weighted concentric rings k-space trajectory (DW-CRT) enables 1H magnetic resonance spectroscopic imaging at 3 Tesla in a clinically feasible timeframe Adam Steel1,2, Mark Chiew3, Peter Jezzard4, Natalie Voets4, Puneet Plaha4, M. Albert Thomas5, Charlotte J Stagg4, and Uzay E Emir6 1Nuffield Department of Medicine, University of Oxford, Headington, United Kingdom, 2National Institute of Mental Health, National Institutes of Health, Bethesda, DC, United States, 3Nuffield Department of Clinical Neuroscience, University of Oxford, Headington, United Kingdom, 4Nuffield Department of Clinical Neurosciences, University of Oxford, Headington, 1271 United Kingdom, 5Department of Radiology, University of California Los Angelas, Los Angeles, CA, United States, 6School of Health Sciences, Purdue University, West Lafayette, IN, United States In this study, we demonstrate that a metabolite-cycled semi-LASER pulse localization with density-weighted concentric rings trajectory (DW-CRT) enables high-resolution MRSI to be acquired at 3 Tesla within a clinically feasible acquisition time. High-resolution (5 x 5 x 10 mm3) DW-CRT feasibility at 3T was assessed in 6 healthy volunteers. Subsequently, the clinical utility of this approach was demonstrated by mapping the presence of 2-HG in a patient with a grade III oligodendroglioma tumor. Standardized Parameterization of Echo-Planar Compressed Sensing MRSI Acquisition and Reconstruction Jason C. Crane1, Marram P Olson1, Yan Li1, Maryam Vareth1, Hsin-Yu Chen1, Zihan Zhu1, Sukumar Subramaniam1, Peder E.Z. Larson1, Duan Xu1, Daniel B. Vigneron1, and Sarah J. Nelson1 1272 1Department of Radiology and Biomedical Imaging, UCSF, San Francisco, CA, United States Advanced MRSI acquisition strategies can be complex to implement and require customized reconstruction software, typically designed for a specific raw file format and that relies upon a priori knowledge of the specific implementation of the pulse sequence being applied. The ISMRMRD format1 has begun to address standardization in describing data acquisition parameters for different types of imaging data, but further development is needed. Here we build on this strategy by demonstrating XML encoding of parameters that describe flyback echo-planar, compressed sensing MRSI acquisitions being implemented on scanners from multiple vendors at UCSF that can be supported with generalized reconstruction software. SNR and PSF Simulations for k-t Trajectories in MRSI: CSI, EPSI, Rosettes, and Concentric Rings Amir Seginer1 and Assaf Tal1 1273 1Weizmann Institute of Science, Rehovot, Israel We compare, using numeric simulations, the point spread functions (PSF) and the SNR of different trajectories in k-t space for magnetic resonance spectral imaging (MRSI). This is a first step towards evaluating the trajectory of choice while balancing SNR efficiency, scan time, and localization of signal (resolution vs. bleed). JSASSI: A B1 Insensitive Technique for J-Resolved 2D Magnetic Resonance Spectroscopy at 7T Judy Alper1,2, Rebecca E Feldman1, Francesco Padormo1, Priti Balchandani1, and Gaurav Verma1 1Radiology, Icahn School of Medicine At Mount Sinai, New York, NY, United States, 2Biomedical Engineering, City College of New York, New York, NY, United States 1274 Magnetic resonance spectroscopy (MRS) can be used to investigate metabolite concentration changes correlated to neurological and psychiatric diseases. Improved spectral resolution and metabolite quantification in these disorders would add to our understanding of neurodegenerative diseases. JSASSI is a novel technique for localized two-dimensional (2D) MRS, based in part on the JPRESS spectroscopic sequence while implementing pulses from the SASSI sequence. An incrementing Δt1 time delay is introduced for resolving J-coupled metabolites from overlapping resonances. JSASSI was applied in phantoms and in vivo. Metabolite peaks for NAA, Glx, Cr and others were clearly identified using JSASSI. Unambiguous detection and resolution of J-coupled metabolites could facilitate reliable quantification of metabolites such as GABA, with potential applications in characterization and treatment monitoring in psychiatric disorders. 1275 Optimisations for ultra-high resolution MRSI of the brain at 7 T: Towards even higher resolutions and faster measurements Gilbert Hangel1,2, Bernhard Strasser3, Michal Povazan4,5, Eva Hečková1,2, Stephan Gruber1,2, Philipp Moser1,2, Lukas Hingerl1,2, Siegfried Trattnig1,2, and Wolfgang Bogner1,2 1High Feld MR Centre, Medical University of Vienna, Vienna, Austria, 2Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria, 3Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States, 4Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, 5F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States Recently, ultra-high resolution (UHR-) MRSI of the brain at 7 T was successfully demonstrated, allowing metabolic mapping at near-anatomical resolution. With this work, we propose further optimised sequences, one for shorter measurement times of under 5 min and one for even higher in-plane resolutions down to 12 µL, which will allow a more flexible application of UHR_MRSI, and show their possibilities and limitations. Furthermore, the effects of slice thickness for UHR-MRSI were investigated with a second set of measurements. Cross-vendor standardization of a 3 T MRS protocol with semi-LASER Adam Berrington1,2, Dinesh K Deelchand3, James Joers3, Michal Považan1,2, Michael Schär1, Joseph Gillen1,2, Peter B Barker1,2, and Gülin Öz3 1Russell H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2F. M. Kirby Center for Functional Brain Imaging, Kennedy 1276 Krieger Institute, Baltimore, MD, United States, 3Center for Magnetic Resonance Reseach, University of Minnesota, Minneapolis, MN, United States Acceptance of 1H-MRS for clinical use is hindered by variability in methodology across platforms. Cross-vendor standardization is thus desirable for large-scale studies to be conducted. Here, we standardize a semi-LASER scheme (TE=30 ms) with identical pulses, inter-pulse durations and acquisition protocol in phantom and healthy volunteers on Philips and Siemens 3 T systems. The implemented method resulted in high quality spectra with matched SNR, linewidth and spectral patterns in phantom and similar estimated metabolite concentrations in vivo: between-subject CVs for NAA were (2.6-11.0)% and (3.3-10.2)% for Philips and Siemens, respectively. This method highlights the potential for pooling data across multiple sites. Intrinsic inversion recovery-based macromolecular nulling in MEGA-PRESS 1H-MR brain spectra Alexander Gussew1, Andreas Masek1, Martin Krämer1, and Jürgen R. Reichenbach1 1Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany 1277 The reliability of 1H-MRS MEGA-PRESS measurements of inhibitory neurotransmitter GABA in the human brain typically suffers from macromolecular (MM) contaminations of GABA resonances. In this work, we present a novel MM suppression approach, which relies on adiabatic inversion of the longitudinal magnetization of both metabolites and MMs prior to playing out the MEGA-PRESS editing scheme, which is applied after an inversion time delay (TI) corresponding to the zero-crossing of MM magnetization. As demonstrated in healthy subjects, this new approach ensures appropriate MM suppression and provides additional GABA signal gain compared to the commonly applied approach with symmetrical MM editing. What is the optimal ROI size for single voxel MRS in global brain pathology? Maike Hoefemann1, Victor Adalid1, and Roland Kreis1 1Depts. Radiology and Biomedical Research, University of Bern, Bern, Switzerland 1278 The purpose of this study was to investigate optimal voxel size (VS) as a compromise between increasing SNR and decreasing linewidth under the side-constraint of minimal artifact levels and to investigate potential benefits from considering signals from single coil elements separately. Eight different VS were evaluated; hinting at optimal VS of 60 cm³ and indicating that lineshape information from unsuppressed water should be included in the fitting process. Differences in single coil elements show substantial impacts on spectral quality, indicating that individual processing and exclusion of certain channels is superior to the standard procedure of an indiscriminate weighted sum. ISIS based Relaxation Enhanced MR spectroscopy (iRE-MRS) for downfield spectroscopy at short echo times Sonia I. Goncalves1 and Noam Shemesh1 1279 1Neuroplasticity and Neural Activity Lab, Champalimaud Foundation, Lisbon, Portugal MRS is a versatile technique that allows for the non-invasive in-vivo exploration of tissue metabolism. In most MRS pulse sequences based on broadband excitation, the acquisition is preceded by water saturation pulses that suppress the water bulk signal and implicitly also exchangeable protons downfield of water. We introduce a new method for short-TE downfield MRS and show that it detects multiple peaks in-vivo that extend beyond 9