SHORT ECHO TIME DUALBAND SPATIAL-SPECTRAL PULSE SEQUENCE FOR BRAIN MRSI AT 3T

3T 脑 MRSI 短回波时间双频空间频谱脉冲序列

• 批准号: 7358768
• 负责人: Priti Balchandani
• 金额: $ 2.49万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7358768
• 关键词: SHORT; ECHO; TIME; DUALBAND; SPATIAL

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: 1H Magnetic resonance spectroscopic imaging (1H MRSI) is a useful technique for measuring brain metabolites. Dualband spatial-spectral (SPSP) pulses have been designed at 3T for fully exciting the metabolites of interest, partially exciting water, while suppressing lipids. However, in these sequences, the 180¿ SPSP pulses must have nonlinear phase (along the spectral direction) in order to stay below RF peak power limits and consequently both 180¿ pulses in the PRESS excitation are relatively long. This limits TE to a minimum of 90 ms for the brain. In this study, the use of a PRESS sequence with only one dualband spatial-spectral linear phase 90¿ pulse and two standard spatial 180¿ pulses is proposed for brain MRSI. This sequence provides spectral selectivity while allowing significantly shorter echo times than existing SPSP PRESS sequences for the brain. Methods and Discussion: A linear phase 90¿ dualband SPSP pulse was designed using twenty one linear phase subpulses that could excite a slice as thin as 5 mm. The passband for the pulse encompassed choline at 3.2 ppm to NAA at 2.0 ppm while suppressing the lipids at 1.3 ppm and below. The partial water band was designed to excite 2% of the water signal at 4.7 ppm. The final pulse duration was 24 ms resulting in TE=60 ms. The dualband SPSP 90¿ pulse had very low ripple in the metabolite passband but considerable ripple in the partial water passband. However, since we are only using water as a frequency reference and not concerned with its magnitude, this ripple is tolerable. Phantom and in vivo studies demonstrate the new pulse sequence achieved the targeted design parameters. References: [1] Star-Lack JM, et al. Magn Reson Med 2000; 43:325-330. [2] Cunningham CH, et al. Magn Reson Med. 2005 May; 53(5):1033-9. [3] Barker PB, et al. Magn Reson Med. 2001 May;45(5):765-9. Acknowledgements: Lucas Foundation, NIH RR09784,

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。1H磁共振波谱成像（1H MRSI）是一种测量脑代谢物的有用技术。双波段空间光谱（SPSP）脉冲被设计为在3T下完全激发感兴趣的代谢物，部分激发水，同时抑制脂质。然而，在这些序列中，180¿SPSP脉冲必须具有非线性相位（沿着频谱方向），以便保持在RF峰值功率限制之下，因此PRESS激励中的180¿脉冲相对较长。这将大脑的TE限制在至少90毫秒。在这项研究中，提出了使用只有一个双频空间光谱线性相位90′脉冲和两个标准空间180′脉冲的PRESS序列进行脑磁共振成像。该序列提供了光谱选择性，同时允许比现有的大脑SPSP PRESS序列显着缩短回声时间。方法与讨论：利用21个线性相位子脉冲设计了一种线性相位90°双频SPSP脉冲，该脉冲可以激发薄至5 mm的薄片。该脉冲的通带包括3.2 ppm的胆碱到2.0 ppm的NAA，同时抑制1.3 ppm及以下的脂质。部分水波段被设计为在4.7 ppm时激发2%的水信号。最终脉冲持续时间为24毫秒，导致TE=60毫秒。双频spsp90¿脉冲在代谢物通带有很低的纹波，但在部分水通带有相当大的纹波。然而，由于我们只使用水作为频率参考，而不关心其幅度，因此这种波纹是可以容忍的。幻影和体内研究表明，新的脉冲序列达到了目标设计参数。参考文献：[1]Star-Lack JM等。Magn reason Med 2000；43:325 - 330。[10] Cunningham CH，等。2005年5月；53(5): 1033 - 9。bbb10 Barker PB，等。中华医学杂志。2001;45(5):765- 969。致谢：Lucas Foundation， NIH RR09784；