Cunningham Charles H, Vigneron Daniel B, Marjanska Malgorzata, Chen Albert P, Xu Duan, Hurd Ralph E, Kurhanewicz John, Garwood Michael, Pauly John M
Department of Electrical Engineering, Stanford University, California, USA.
Magn Reson Med. 2005 May;53(5):1033-9. doi: 10.1002/mrm.20478.
Magnetic resonance spectroscopic imaging (MRSI) has proven to be a powerful tool for the metabolic characterization of prostate cancer in patients before and following therapy. The metabolites that are of particular interest are citrate and choline because an increased choline-to-citrate ratio can be used as a marker for cancer. High-field systems offer the advantage of improved spectral resolution as well as increased magnetization. Initial attempts at extending MRSI methods to 3 T have been confounded by the J-modulation of the citrate resonances. A new pulse sequence is presented that controls the J-modulation of citrate at 3 T such that citrate is upright, with high amplitude, at a practical echo time. The design of short (14 ms) spectral-spatial refocusing pulses and trains of nonselective refocusing pulses are described. Phantom studies and simulations showed that upright citrate with negligible sidebands is observed at an echo time of 85 ms. Studies in a human subject verified that this behavior is reproduced in vivo and demonstrated that the water and lipid suppression of the new pulse sequence are sufficient for application in prostate cancer patients.
磁共振波谱成像（MRSI）已被证明是一种用于前列腺癌患者治疗前后代谢特征分析的有力工具。特别令人感兴趣的代谢物是柠檬酸盐和胆碱，因为胆碱与柠檬酸盐的比例增加可作为癌症的标志物。高场系统具有提高光谱分辨率和增加磁化强度的优势。将MRSI方法扩展到3T的初步尝试因柠檬酸盐共振的J调制而受到困扰。本文提出了一种新的脉冲序列，该序列可在3T时控制柠檬酸盐的J调制，使得在实际回波时间时柠檬酸盐呈直立状态且幅度较高。描述了短（14ms）光谱空间重聚焦脉冲和非选择性重聚焦脉冲序列的设计。体模研究和模拟表明，在85ms的回波时间可观察到具有可忽略边带的直立柠檬酸盐。在人体受试者中的研究证实了这种行为在体内的重现，并表明新脉冲序列的水和脂质抑制足以应用于前列腺癌患者。
