Shen J, Shungu D C, Rothman D L
Department of Internal Medicine, School of Medicine, Yale University, New Haven, Connecticut, USA.
Magn Reson Med. 1999 Jan;41(1):35-42. doi: 10.1002/(sici)1522-2594(199901)41:1<35::aid-mrm7>3.0.co;2-c.
A gradient-based multiple quantum filtering method is presented for in vivo chemical shift imaging of gamma-aminobutyric acid (GABA) in the human brain, which provides effective suppression of the overlapping creatine singlet with close to optimal detection efficiency. It is shown by product operator calculations and coherence pathway analysis that under conditions of no B1 and B0 inhomogeneity gradient filtering retains 75% of the two outer resonance lines of the GABA-4 triplet with no creatine contamination. A variation of the method with 100% retention of the GABA-4 outer resonance lines but higher sensitivity to B1 inhomogeneity is also discussed. By using a localized version of the sequence with an 8-cm surface coil for transmission and detection, it was found in phantom experiments at 2.1 T that a 69% signal retention of the two outer resonance lines of the GABA-4 triplet was achieved relative to a spin echo sequence with inhibition of GABA J modulation. A creatine suppression ratio of 2000:1 was measured. The use of the method for chemical shift imaging of GABA is demonstrated by coronal images obtained from phantoms and from the occipital lobe of a healthy volunteer.
本文提出了一种基于梯度的多量子滤波方法，用于人脑γ-氨基丁酸（GABA）的体内化学位移成像，该方法能有效抑制与肌酸单重峰的重叠，并具有接近最佳的检测效率。通过乘积算符计算和相干路径分析表明，在不存在B1和B0不均匀性的条件下，梯度滤波可保留GABA - 4三重峰的两条外部共振线的75%，且无肌酸污染。还讨论了该方法的一种变体，它能100%保留GABA - 4外部共振线，但对B1不均匀性更敏感。通过使用带有8厘米表面线圈用于发射和检测的序列局部化版本，在2.1 T的体模实验中发现，相对于抑制GABA J调制的自旋回波序列，GABA - 4三重峰的两条外部共振线的信号保留率达到69%。测得肌酸抑制比为2000:1。从体模和健康志愿者枕叶获得的冠状图像证明了该方法用于GABA化学位移成像的可行性。
