Traditional Posters: Miscellaneous

Ulrike Dydak^1,2, Malgorzata Marjanska³, Stefan Posse<sup>4,5

1</sup>School of Health Sciences, Purdue University, West Lafayette, IN, United States; ²Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, United States; ³Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN, United States; ⁴Department of Neurology, University of New Mexico School of Medicine, Albuquerque, NM, United States; ⁵Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, NM, United States

The feasibility of GABA-edited magnetic resonance spectroscopic imaging with short scan times is demonstrated both in a phantom and in vivo by combining the high-speed (Proton-Echo-Planar-Spectroscopic-Imaging) PEPSI sequence with the MEGA editing scheme. We show MEGA-PEPSI spectra from an axial slice in the human brain acquired at 3 T within < 5 min with a nominal resolution of 8 ml. The signal of GABA and co-edited macromolecules is clearly discernable in most spectra and was fitted with LCModel, using a simulated basis for this sequence. Spectral fitting of the GABA resonance was feasible with Cramer Rao lower bounds < 20 %.

962. Correction of Eddy Currents for Time-Domain-Interleaved Blipped-Phase-Encoding Echo-Planar Spectroscopic Imaging

Yoshitaka Bito¹, Koji Hirata¹, Satoshi Hirata¹, Toru Shirai¹, Toshihiko Ebisu², Yuko Kawai³, Yosuke Otake¹, Yoshihisa Soutome¹, Hisaaki Ochi¹, Masahiro Umeda³, Toshihiro Higuchi⁴, Chuzo Tanaka<sup>4

1</sup>Central Research Laboratory, Hitachi, Ltd., Kokubunji-shi, Tokyo, Japan; ²Neurosurgery, Nantan General Hospital, Nantan-shi, Kyoto, Japan; ³Medical Informatics, Meiji University of Integrative Medicine, Nantan-shi, Kyoto, Japan; ⁴Neurosurgery, Meiji University of Integrative Medicine, Nantan-shi, Kyoto, Japan

High-speed spectroscopic imaging using the echo-planar technique is sometimes distorted by eddy currents. We developed an eddy current correction technique for time-domain-interleaved blipped-phase-encoding echo-planar spectroscopic imaging (TDI-BPE-EPSI). This technique uses correction of spatial shift due to chemical shifts in the blipped-phase-encoding direction before applying eddy current correction based on the water signal. Correction of eddy currents is demonstrated by applying this technique to a phantom and a rat brain in vivo. This technique is shown to be also useful in diffusion-weighted spectroscopic imaging, which causes more eddy currents due to strong diffusion gradients.

963. Comparison of Automatic and Manual Prescription Protocols for Brain 3D MRSI

Eugene Ozhinsky^1,2, Daniel B. Vigneron^1,3, Susan M. Chang⁴, Sarah J. Nelson<sup>1,3

1</sup>Surbeck Laboratory of Advanced Imaging, Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; ²UCSF/UCB Joint Graduate Group in Bioengineering, University of California, San Francisco, San Francisco, CA, United States; ³Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States; ⁴Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States

In this work we have evaluated the coverage volume and data quality of 3D MRSI protocols with manual and automatic prescription of outer-volume suppression and selected volume. Automatic oblique prescription allowed approximately 3x increase in coverage volume with no decline in data quality.

964. Inductively Coupled Reference Signal Injection Method for Quantitative MRI