基于快速梯度回波序列的氨基质子转移成像

摘要

磁共振氨基质子转移成像技术已经成为一种对机体内蛋白质浓度及活性检测的新方法。目前，磁共振氨基质子转移成像序列设计主要采用预饱和激发脉冲结合回波平面成像序列采集信号，但是在高场系统中回波平面成像序列容易产生图像变形、信号丢失等问题。文章提出一种用快速梯度回波代替回波平面成像序列进行信号采集的序列设计方法，在仿体上研究了不同浓度氨基酸信号强度随预饱和脉冲偏置频率变化的关系，经过图像后处理得到了仿体的氨基质子转移图像。结果显示，仿体氨基质子转移图像无明显畸变，同时对氨基质子转移的转移率与氨基浓度做了定量分析。%Magnetic resonance amide proton transfer imaging is a novel technical to detect the concentration and viability of protein in vivo. Currently, amide proton transfer (APT) imaging is commonly implemented by the echo planar imaging (EPI) sequence with a series of pre-saturation pulses. However, EPI images suffer from image distortion and signal decay in higher field MR (magnetic resonance) system. In this paper, we proposed to replace EPI with the fast gradient echo sequence for APT imaging. Specifically, the APT data were acquired by a series of pre-saturation pulses with different offset frequency following a fast gradient echo readout with small lfip angle. The APT images were then obtained with ifeld inhomogeneity correction. Experimental results show that the images are free of distortion and the quantitative analysis of APT ratio with the concentration of amide proton exhibits good consistency.