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Many endeavors of improving chemical shift imaging (CSI) techniques have been made during last two decades. Good examples of two-dimensional CSI and three-dimensional CSI can be found in the literature. However, clinical CSI using available sequences is still not satisfactory. The purpose of this study was to assess the effect of outer volume saturation bands on signal homogeneity in MR 2D chemical shift imaging. The 2D CSI scans were acquired using a point resolved spectroscopy (PRESS) CSI sequence on a phantom filled with brain metabolites. A single PRESS volume of interest was prescribed graphically. The acquisition matrix was 18x18 phase encodings over a 24-cm FOV. Identical acquisitions were obtained with and without outer-volume saturation bands. After initial acquisition was obtained, four more acquisitions were repeated for both studies with and without saturation bands. Identical five groups of voxels were compared for both studies. Standard deviations of metabolite ratios were calculated in each group for both studies. Spectra obtained without outer-volume saturation bands showed signal to noise gradient with higher concentration of signal within voxels at the center of the volume of interest. Outer volume saturation bands reduced this gradient. In general, standard deviations of metabolite ratios with saturation bands were smaller than those without saturation bands. Improved spatial homogeneity of spectra in voxels of CSI with saturation bands was obtained. Outer-volume saturation bands improve spatial signal homogeneity of chemical shift imaging.

Understanding the abundance and distribution characteristics of FeO on the surface of the Moon is important for investigating its evolution. The current high resolution maps of the global FeO abundance are mostly produced with visible and near infrared reflectance spectra. The Christiansen Feature (CF) in mid-infrared has strong sensitivity to lunar minerals and correlates to major elements composing minerals. This paper investigates the possibility of mapping global FeO abundance using the CF values from the Diviner Lunar Radiometer Experiment aboard the Lunar Reconnaissance Orbiter (LRO) mission. A high correlation between the CF values and FeO abundances from the Apollo samples was found. Based on this high correlation, a new global map (±60 • ) of FeO was produced using the CF map. The results show that the global FeO average is 8.2 wt.%, the highland average is 4.7 wt.%, the global modal abundance is 5.4 wt.% and the lunar mare mode is 15.7 wt.%. These results are close to those derived from data provided by Clementine, the Lunar Prospector Gamma Ray Spectrometer (LP-GRS) and the Chang'e-1 Interference Imaging Spectrometer (IIM), demonstrating the feasibility of estimating FeO abundance based on the Diviner CF data. The near global FeO abundance map shows an enrichment of lunar major elements.

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