Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany.
NMR Biomed. 2012 Aug;25(8):1000-6. doi: 10.1002/nbm.2764. Epub 2012 Jan 31.
A novel spectroscopic method for submillisecond TEs and three-dimensional arbitrarily shaped voxels was developed and applied to phantom and in vivo measurements, with additional parallel excitation (PEX) implementation. A segmented spherical shell excitation trajectory was used in combination with appropriate radiofrequency weights for target selection in three dimensions. Measurements in a two-compartment phantom realized a TE of 955 µs, excellent spectral quality and comparable signal-to-noise ratios between accelerated (R = 2) and nonaccelerated modes. The two-compartment model allowed a comparison of the spectral suppression qualities of the method and, although outer volume signals were suppressed by factors of 1434 and 2246 compared with the theoretical unsuppressed case for the clinical and PEX modes, respectively, incomplete suppression of the outer volume (935 cm(3) compared with a target volume of 5.86 cm(3) ) resulted in a spectral contamination of 10.2% and 6.5% compared with the total signal. The method was also demonstrated in vivo in human brain on a clinical system at TE = 935 µs with good signal-to-noise ratio and spatial and spectral selection, and included LCModel relative quantification analysis. Eight metabolites showed significant fitting accuracy, including aspartate, N-acetylaspartylglutamate, glutathione and glutamate.
一种新的亚毫秒级 TEs 和任意三维形状体素的光谱方法被开发出来，并应用于体模和体内测量，同时实现了额外的并行激发 (PEX)。分段球形壳激发轨迹与适当的射频权重相结合，用于三维目标选择。在两腔室体模中的测量实现了 955 µs 的 TE、出色的光谱质量和可比较的信噪比，在加速（R = 2）和非加速模式之间。两腔室模型允许比较该方法的光谱抑制质量，尽管与临床和 PEX 模式的理论未抑制情况相比，外体积信号分别被抑制了 1434 和 2246 倍，但外体积的不完全抑制（与目标体积 5.86 cm(3) 相比，为 935 cm(3)）导致与总信号相比，光谱污染分别为 10.2%和 6.5%。该方法还在临床系统上对人体大脑进行了体内演示，具有良好的信噪比、空间和光谱选择，包括 LCModel 相对定量分析。八种代谢物显示出显著的拟合准确性，包括天冬氨酸、N-乙酰天门冬氨酸谷氨酸、谷胱甘肽和谷氨酸。
