Reeder Scott B, Brittain Jean H, Grist Thomas M, Yen Yi-Fen
Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
J Magn Reson Imaging. 2007 Oct;26(4):1145-52. doi: 10.1002/jmri.21089.
To describe a new least-squares chemical shift (LSCSI) method for separation of chemical species with widely spaced peaks in a sparse spectrum. The ability to account for species with multiple peaks is addressed.
This method is applied to imaging of (13)C-labeled pyruvate and its metabolites alanine, pyruvate, and lactate. The method relies on a priori knowledge of the resonant frequencies of the different chemical species, as well as the relative signal from the two pyruvate peaks, one of which lies near the alanine peak. With this information a least-squares method was utilized for separation of signal from the three metabolites, facilitating tremendous reductions in the amount of data required to decompose the different chemical species. Optimization of echo spacing for maximum noise performance of the signal separation is also described.
Imaging an enriched (13)C phantom at 3.0T, the LSCSI method demonstrates excellent metabolite separation, very similar to echo planar spectroscopic imaging (EPSI), while only using 1/16th as much data.
This approach may be advantageous for in vivo hyperpolarized (13)C metabolic applications for reduced scan time compared with EPSI.
描述一种新的最小二乘化学位移（LSCSI）方法，用于在稀疏光谱中分离具有宽间距峰的化学物质。探讨了处理具有多个峰的物质的能力。
该方法应用于对（13）C标记的丙酮酸及其代谢产物丙氨酸、丙酮酸和乳酸的成像。该方法依赖于不同化学物质共振频率的先验知识，以及来自两个丙酮酸峰的相对信号，其中一个峰靠近丙氨酸峰。利用这些信息，采用最小二乘法分离三种代谢物的信号，极大地减少了分解不同化学物质所需的数据量。还描述了为实现信号分离的最大噪声性能而对回波间距进行的优化。
在3.0T下对富含（13）C的体模进行成像时，LSCSI方法显示出优异的代谢物分离效果，与回波平面光谱成像（EPSI）非常相似，而仅使用了其1/16的数据量。
与EPSI相比，这种方法对于体内超极化（13）C代谢应用可能具有优势，可减少扫描时间。
