Optimal timing for in vivo 1H-MR spectroscopic imaging of the human prostate at 3T
Optimal timing for in vivo 1H-MR spectroscopic imaging of the human prostate at 3T
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DOI：
10.1002/mrm.20468
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发表时间：
2005-06-01
影响因子：
3.3
通讯作者：
Heerschap, A
中科院分区：
文献类型：
--
作者：
Scheenen, TWJ;Gambarota, G;Heerschap, A
人类前列腺的质子磁共振波谱成像(H-1-MRSI)具有有趣的临床潜力，可以通过将磁场强度从1.5T增加到3T来改进。为了优化3T人体前列腺光谱成像的脉冲定时，理论和实践上的考虑都是必要的。对于体内检测柠檬酸盐的强耦合自旋系统，不仅信号的光谱形状应该容易识别，而且所用的时间应该在相当短的回声时间(TES)产生MR信号。在这项研究中，用密度矩阵计算模拟了柠檬酸盐亚甲基质子的光谱形状，并用模体测量进行了验证。用2D光谱成像序列在前列腺癌患者中测量了不同计算的最佳光谱形状。计算了前列腺中感兴趣的两种主要代谢物柠檬酸盐和胆碱的T-1和T-2松弛时间。我们得出结论：在体点分辨光谱(PRESS)3T成像的最佳时序是90度-25ms-180度-37.5ms-180度-12.5ms-ECHO的脉间时序。750ms的短重复时间(Tr)部分饱和了胆碱信号，但增加了柠檬酸盐的单位时间信噪比，并容纳了椭圆采样k空间的最大数量的加权平均，以实现准确定位和最小的单个光谱污染。这是通过活体完整的前列腺的3D光谱成像实验来说明的。(C)2005年Wiley-Liss，Inc.
Proton MR spectroscopic imaging (H-1-MRSI) of the human prostate, which has an interesting clinical potential, may be improved by increasing the magnetic field strength from 1.5T to 3T. Both theoretical and practical considerations are necessary to optimize the pulse timing for spectroscopic imaging of the human prostate at 3T. For in vivo detection of the strongly coupled spin system of citrate, not only should the spectral shape of the signal be easy to identify, but the timing used should produce MR signals at reasonably short echo times (TEs). In this study the spectral shape of the methylene protons of citrate was simulated with density matrix calculations and checked with phantom measurements. Different calculated optimal spectral shapes were measured in patients with prostate cancer with a 2D spectroscopic imaging sequence. T-1 and T-2 relaxation times were calculated for citrate and choline, the two major metabolites of interest in the prostate. We conclude that the optimum timing for in vivo point-resolved spectroscopy (PRESS) imaging at 3T is an interpulse timing sequence of 90 degrees - 25 ms - 180 degrees - 37.5 ms - 180 degrees - 12.5 ms - echo. A short repetition time (TR) of 750 ms partially saturates choline signals, but increases the SNR per unit time for citrate, and accommodates a maximum number of weighted averages of an elliptically sampled k-space for accurate localization and minimal contamination of the individual spectra. This is illustrated by means of a 3D spectroscopic imaging experiment in a complete prostate in vivo. (c) 2005Wiley-Liss, Inc.