基于可控混叠的快速并行磁共振成像初步研究

Preliminary Research on Controlled Aliasing in Parallel Imaging Results in Higher Acceleration

基于可控混叠的快速并行成像是目前磁共振快速成像领域的研究热点。该技术在传统的多层同时激发成像原理的基础上,利用相位调制后的多频带射频脉冲同时激发多层,避免被激发的多层图像在同一区域叠加,有利于利用不同层面线圈灵敏度不同的先验信息将不同层的图像分离出来。该技术不仅能够成倍地减少扫描时间,而且所得图像的信噪比相对传统的多层同时激发技术有大幅提升。文章详细介绍基于可控混叠的快速并行成像技术的原理,并给出我们基于该技术与梯度回波序列相结合的快速成像序列及其在水模和人体上的初步测试结果。

Controlled aliasing in parallel imaging results in higher acceleration（CAIPIRINHA） is a key technique for fast magnetic resonance imaging because of its high acceleration rate and high signal-to-noise ratio（SNR）. Based on the traditional simultaneous multiple-slices excitation（SMS）, CAIPIRINHA utilizes phase-modulated radio frequency pulse to simultaneously excite multiple slices to reduce overlaps of different excited slices in the same region, which benefi ts the separation of individual images with the help of prior information of coil sensitivity. CAIPIRINHA can largely reduce scanning time according to the number of simultaneously excited slices. Additionally, compared with traditional SMS, CAIPIRINHA also increases the SNR of the reconstructed images. In this paper, the principle of CAIPIRINHA was introduced and the sequence of CAIPIRINHA combined with gradient echo was presented as well as the preliminary experiment results on phantom and human brain.