MRI-Based Image Signal-to-Noise Ratio Enhancement with Different Receiving Gains in K-Space.

Lin Wu,Tao Zhang,Shuang Zhang

doi:10.3390/s21165296

Abstract

Echo signals in different regions in the k-space of magnetic resonance imaging (MRI) data possess different amplitudes. The signal-to-noise ratio (SNR) of a received signal can be improved by differentially setting the receiving gain (RG) parameter in different areas of the k-space. Previously, the k-space data splicing method and the gain normalization implementation method were not specifically investigated; however, this study focuses on this aspect. Specifically, to improve the SNR, three RGs and MRI scans are herein designed for each gain parameter using the gradient echo sequence to obtain one group of k-space data. Subsequently, the three groups of experimental k-space data obtained using MRI scans are spliced into one group of k-space data. For the splicing process, a method for gain and phase correction and compensation is developed that normalizes different RG parameters in the k-space. The experimental results indicate that the developed methods improve the SNR by 5–13%. When the RGs are set to other combinations, the k-space data splicing and gain normalization methods presented in this paper are still applicable.

Highlights

Signal acquisition research has far focused on the maximum signal-to-noise ratio (SNR) at individual amplitude points to prevent saturation under a fixed receiving gain (RG)
Data obtained under different k-space gain parameters are normalized by the amplitude under the maximum RG parameter
Comparison between the images reconstructed from the spliced k-space data and the kspace data obtained under the lowest RG was further performed to verify the effectiveness of the proposed k-space data splicing and gain normalization methods

Summary

Introduction

Signal acquisition research has far focused on the maximum signal-to-noise ratio (SNR) at individual amplitude points to prevent saturation under a fixed receiving gain (RG). Several researchers have attempted to improve the SNR by reducing the receiver noise [1,2,3,4,5,6,7,8]. When compared with analog receivers, digital receivers can reduce the noise of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI), thereby improving the SNR [1,2,3,4]. For conventional MRI digital receivers (3T), analog-to-digital convertors (ADCs) with a conversion rate of 100 MHz are typically used for under-sampling and analog-to-digital signal conversion [5]. Under the normal temperature operating mode, the SNR of a system does not improve even if the ADC sampling rate exceeds 100 MHz, owing to the impact of physiological noise from the human body [6].

Objectives

Results

Conclusion