利用动态接收增益提高磁共振成像信噪比的方法  

Improving Signal-to-Noise Ratio in Magnetic Resonance Imaging Using Dynamic Receiver Gain

作　　者：孙宏宇[1] 汤伟男[2] 王为民[1] 

机构地区：[1]北京大学信息科学技术学院量子电子学研究所,北京100871 [2]北京大学磁共振成像研究中心,北京100871

出　　处：《波谱学杂志》2014年第4期515-522,共8页Chinese Journal of Magnetic Resonance

基　　金：国家科技重大专项资助项目(2011ZX05008-004)

摘　　要：提出了一种提高磁共振成像(MRI)信噪比的有效方法.该方法在每次采集回波信号前,能够快速、灵活地控制MRI接收机的增益,实现磁共振信号动态范围的压缩;在图像重建之前采用双精度浮点运算扩展动态范围压缩的磁共振信号,最终得到信噪比提高的重建图像.在1.5 T超导MRI系统上进行了自旋回波序列的水模成像,实验结果表明,相比传统的基于固定接收增益的扫描图像,利用该方法得到的T1加权图像信噪比可以提高10%.和其他提高磁共振信号动态范围的方法相比,该方法无需增加额外硬件电路,避免多次采集图像,因而具有实现成本低的优点,是一种提高MRI信噪比的有效方法.A method to increase signal-to-noise ratio （SNR） in magnetic resonance imaging using dynamic receiver gain was proposed. In the method, the receiver gain was adjusted dynamically according to amplitude of each echo signal before acquisition. By doing so, the receiver dynamic range could be optimized to improve SNR of each acquisition. To reconstruct the images, a double-precision floating-point arithmetic processing procedure was used to expand the dynamic range of all acquisitions to the same scale. Imaging experiments were conducted using the proposed method on a 1.5 T clinical MRI scanner. The results showed that the SNR of T1-weighted images could be improved by approximately 10%, compared to the fixed-receiver-gain images. More importantly, the method proposed needs no extra circuits or multiple time-consuming scans. It is concluded that using dynamic receiver gain for each acquisition is an effective way to improve SNR in MR imaging, especially for high-resolution and high-filed imaging applications.

关 键 词：磁共振成像(MRI) 动态接收增益 量化噪声 动态范围 信噪比 

分 类 号：O482.53[理学—固体物理]