Prescot Andrew P, Shi Xianfeng, Choi Changho, Renshaw Perry F
Brain Institute, University of Utah, Salt Lake City, UT, USA; Department of Radiology, University of Utah School of Medicine, Salt Lake City, UT, USA.
NMR Biomed. 2014 Aug;27(8):863-9. doi: 10.1002/nbm.3115. Epub 2014 May 28.
The accuracy of metabolite concentrations measured using in vivo proton ((1) H) MRS is enhanced following correction for spin-spin (T2 ) relaxation effects. In addition, metabolite proton T2 relaxation times provide unique information regarding cellular environment and molecular mobility. Echo-time (TE) averaging (1) H MRS involves the collection and averaging of multiple TE steps, which greatly simplifies resulting spectra due to the attenuation of spin-coupled and macromolecule resonances. Given the simplified spectral appearance and inherent metabolite T2 relaxation information, the aim of the present proof-of-concept study was to develop a novel data processing scheme to estimate metabolite T2 relaxation times from TE-averaged (1) H MRS data. Spectral simulations are used to validate the proposed TE-averaging methods for estimating methyl proton T2 relaxation times for N-acetyl aspartate, total creatine, and choline-containing compounds. The utility of the technique and its reproducibility are demonstrated using data obtained in vivo from the posterior-occipital cortex of 10 healthy control subjects. Compared with standard methods, distinct advantages of this approach include built-in macromolecule resonance attenuation, in vivo T2 estimates closer to reported values when maximum TE ≈ T2 , and the potential for T2 calculation of metabolite resonances otherwise inseparable in standard (1) H MRS spectra recorded in vivo.
在对自旋 - 自旋（T2）弛豫效应进行校正后，使用体内质子（（1）H）磁共振波谱（MRS）测量的代谢物浓度准确性会提高。此外，代谢物质子T2弛豫时间提供了有关细胞环境和分子流动性的独特信息。回波时间（TE）平均（1）H MRS涉及多个TE步骤的采集和平均，由于自旋耦合和大分子共振的衰减，这极大地简化了所得光谱。鉴于简化的光谱外观和固有的代谢物T2弛豫信息，本概念验证研究的目的是开发一种新颖的数据处理方案，以便从TE平均（1）H MRS数据中估计代谢物T2弛豫时间。光谱模拟用于验证所提出的TE平均方法，以估计N - 乙酰天门冬氨酸、总肌酸和含胆碱化合物的甲基质子T2弛豫时间。使用从10名健康对照受试者枕后皮质获得的体内数据证明了该技术的实用性及其可重复性。与标准方法相比，该方法的明显优势包括内置的大分子共振衰减、当最大TE≈T2时，体内T2估计值更接近报告值，以及在体内记录的标准（1）H MRS光谱中原本无法分离的代谢物共振进行T2计算的潜力。
