FAST 1H MISSING-PULSE SSFP CHEMICAL SHIFT IMAGING OF THE HUMAN BRAIN AT 7 TESLA

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Recently, steady state free precession (SSFP) chemical shift imaging techniques have been introduced which are particularly attractive because of their short measurement time (Tacq) and high sensitivity (SNR/Tacq). The main disadvantages of SSFP-based methods are that the effects of both T1 and T2 on the signal intensities complicate quantitation and the spectral resolution is limited due to the short TRs. Whereas the former is an inherent problem, the latter is less problematic at high field strengths such as 7 T due to the increased dispersion of the chemical shift. Spectroscopic missing pulse SSFP (spMP-SSFP) has the advantage that the full echo can be acquired. This allows data to be analyzed in magnitude mode without spectral line broadening. Therefore, the aim of this work was to implement spMP-SSFP with a spectral-spatial radiofrequency pulse for combined water and lipid suppression at 7 T. The higher field strength provides better signal separation and higher SNR relative to low- and midfield systems. Even when using a relatively small flip angle (45¿) with the currently available RF coil, B1 inhomogeneity has a substantial impact on data quality. Better coil designs and parallel RF transmission techniques should help to reduce the artifacts caused by B1 inhomogeneity. Funding Sources " NIH grants RR09784, AA12388, AA13521. Relevant publications " D. Mayer, D. M. Spielman Fast 1H Missing-Pulse SSFP Chemical Shift Imaging of the Human Brain at 7 Tesla, Proc ISMRM, 15th Annual Meeting, Berlin, 2007, 771.