A trial of 13C spectroscopic imaging utilizing a phased-array coil for 1H parallel imaging. Presidential award proceedings

We attempted to use a surface coil for 13C transmission combined with a 4-channel phased array coil for 1H parallel imaging to observe 1H-detected 13C spectroscopic imaging with high sensitivity in a bottle phantom containing 15 ml of 5% [1-13C]glucose solution. For spectroscopic imaging, we used a combined pulse sequence of gradient-enhanced, heteronuclear, multiple-quantum coherence and chemical shift imaging. We processed data utilizing sense encoding (SENSE), a parallel imaging technique, on an external computer. The 4 surface coils for reception showed a limited area of sensitivity, but the signal-to-noise ratio (SNR) by individual coils in the observed spectra was 10-times higher than that in the spectrum by the volume coil from the whole phantom. Processing to unfold the image data with SENSE was successful when we used spin-echo image data. However, acquisition of good results required complex data, not absolute data, for signal processing. To construct spectroscopic imaging, we integrated the signal intensities corresponding to the spectral peak, and the data acquired had to be an absolute value, not a complex value. In addition, reference data obtained by the volume coil was not as homogeneous as 1H image data because the sensitivity of the 13C surface coil affected the 1H signal intensities of the spectroscopic image. At present, the results of data processing utilizing SENSE are not completely successful for spectroscopic image data, and the method requires further improvement. Considering the SNR of the spectral data observed by the surface coil, however, our trial to use a phased-array coil will be a feasible option to increase sensitivity of 1H-detected 13C spectroscopic imaging. (author)