Signal-to-Noise Ratio Enhancement of MR Images With Variable Gains and K-Space Splicing Method

Increasing the receiving gain (RG) of magnetic resonance imaging (MRI) systems can improve the signal-to-noise ratio (SNR) of MR images. Setting the RG too high; however, may cause partial signal saturation of the K-space data, which will distort the reconstructed images. In this article, we propose a novel and optimized K-space splicing scheme to integrate phase-encoding (PE) lines acquired, respectively, at high RG and normal RG. A detailed implementation process of the K-space splicing method is presented, and a comparative study is conducted using different splicing schemes and multiple sets of K-space data with variable RGs. Based on many trials and experiments, an optimized splicing scheme is selected that approximately 20% of the total PE lines at the K-space center with high RG are replaced by the data acquired with normal RG. This is a good balance between the SNR improvement and easy implementation since it can be generally applied to a variety of RG settings, pulse sequences, and acquisition protocols. The efficacy of the proposed K-space splicing scheme is further verified by more multislice imaging experiments, demonstrating that the image SNR improvement ranges from 30.63% to 36.46% on a spherical homogeneous phantom and from 21.75% to 31.88% on a cylindrical structure phantom. Finally, a practical solution to this splicing scheme is suggested that can be readily integrated into the existing MR system hardware with slight workflow changes and a minimal increase in scan time. This is a great benefit to clinical applications compared to repeated scanning or other K-space splicing methods that may either significantly increase the scan time or require substantial hardware and workflow modifications.