title: Fully automated shim mapping method for spectroscopic imaging of the mouse brain at 9.4 T.
abstract: For spectroscopic imaging studies of the mouse brain, it is critical to obtain optimal B(0) homogeneity over a large region of interest (ROI). In this paper, a fully automated shimming method for mouse brain at 9.4 T, based on B(0) mapping, is described. B(0) maps were obtained using a multislice gradient echo sequence with multiple phase evolution time delays with a novel unwrapping scheme. The unwrapping method allows phase maps with large bandwidths (+/-1 kHz) but with high resolution (0.3 Hz/ degrees ) to be acquired in a single acquisition, thereby minimizing the number of iterations required. The SD of the B(0) over the ROI (8 x 5 x 1 mm) was less than 10 Hz after shimming. Application of this method to the in vivo mouse brain allowed reproducible, high-quality spectroscopic data to be collected with 1-microl voxels.
authors.affiliation: Department of Radiology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA. nmiyasak@aecom.yu.edu
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Miyasaka
authors.forename: Kan
authors.initials: K
authors.lastname: Takahashi
authors.forename: Hoby P
authors.initials: HP
authors.lastname: Hetherington
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001931:Brain Mapping / Q000379:methods*; D003401:Creatine / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D051379:Mice; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine