Fifty-eighth annual meeting of the american association of physicists in medicine
SU-F-I-64: Comparison of Lipid Contents Using STEAM and PRESS with in Vivo High-Resolution Spectra at 9.4 T
The objective of this study is to compare lipid contents using localized point-resolved spectroscopy (PRESS) and stimulated echo acquisition mode (STEAM) sequences to assess lipid resonances in the liver, using in vivo high-resolution spectra at 9.4 T.
The examinations were performed on a Bruker 9.4T scanner using 4-channel animal coil for higher resolution. We used PRESS (repetition time [TR]/ TE = 3500/20 ms; number of signal averages [NSA] = 128; acquisition data points = 2048) and STEAM (TR/TM/TE = 3500/10/20 ms; NSA = 128; acquisition data points = 2048). Lipid relaxations in HF diet mice were estimated at a fixed TR of 5000 ms, and TEs of 20–70 ms. All spectra acquired were processed using the Advanced Method for Accurate, Robust, and Efficient Spectral (AMARES) fitting algorithm including in the Java-based Magnetic Resonance User Interface (jMRUI) software package. Preprocessing was performed using an automatic frequency shift and the Hankel-Lanczos Singular Value Decomposition (HLSVD) filter with subtraction of water peak (4.70 ppm).
To accurately quantify lipid content, a sequence was selected. The total lipid and total saturated fatty acid were differently changed in HF diet mice that underwent PRESS compared with those that underwent STEAM (total lipid, p < 0.05; total saturated fatty acid, p < 0.001). Compared with PRESS, STEAM showed different total unsaturated fatty acid value (p < 0.001). Compared with PRESS, STEAM showed different total unsaturated and poly unsaturated bonds (total unsaturated bond, p<0.001; poly unsaturated bond, p < 0.001).
Due to stronger J-coupling effects on the PRESS sequence, the accurate estimation could not be obtained. STEAM is less sensitive to J-coupling and gives a theoretically more accurate estimate at 9.4T.