Schricker A A, Pauly J M, Kurhanewicz J, Swanson M G, Vigneron D B
Department of Radiology, University of California-San Francisco, San Francisco, California 94143-1290, USA.
Magn Reson Med. 2001 Dec;46(6):1079-87. doi: 10.1002/mrm.1302.
Although MR spectroscopic imaging (MRSI) of the prostate has demonstrated clinical utility for the staging and monitoring of cancer extent, current acquisition methods are often inadequate in several aspects. Conventional 180 degrees pulses can suffer from chemical shift misregistration, and have high peak-power requirements that can exceed hardware limits in many prostate MRSI studies. Optimal water and lipid suppression are also critical to obtain interpretable spectra. While complete suppression of the periprostatic lipid resonance is desired, controlled partial suppression of water can provide a valuable phase and frequency reference for data analysis and an assessment of experimental success in cases in which all other resonances are undetectable following treatment. In this study, new spectral-spatial RF pulses were developed to negate chemical shift misregistration errors and to provide dualband excitation with partial excitation of the water resonance and full excitation of the metabolites of interest. Optimal phase modulation was also included in the pulse design to provide 40% reduction in peak RF power. Patient studies using the new pulses demonstrated both feasibility and clear benefits in the reliability and applicability of prostate cancer MRSI.
尽管前列腺磁共振波谱成像（MRSI）已在癌症分期和监测癌症范围方面显示出临床实用性，但目前的采集方法在多个方面往往存在不足。传统的180度脉冲可能会出现化学位移配准错误，并且具有较高的峰值功率要求，在许多前列腺MRSI研究中可能会超过硬件限制。最佳的水和脂质抑制对于获得可解释的光谱也至关重要。虽然希望完全抑制前列腺周围脂质共振，但对水进行可控的部分抑制可为数据分析提供有价值的相位和频率参考，并在治疗后所有其他共振均无法检测到的情况下评估实验是否成功。在本研究中，开发了新的频谱空间射频脉冲，以消除化学位移配准误差，并提供双频激发，对水共振进行部分激发，对感兴趣的代谢物进行全激发。脉冲设计中还包括了最佳相位调制，以使射频峰值功率降低40%。使用新脉冲的患者研究证明了前列腺癌MRSI在可靠性和适用性方面的可行性和明显优势。
