基于神经网络拟合的腹部化学交换饱和转移成像

doi:10.11938/cjmr20212903

摘要/Abstract

摘要：

磁共振成像（Magnetic Resonance Imaging，MRI）化学交换饱和转移（Chemical Exchange Saturation Transfer，CEST）技术在临床诊断中展现了巨大的潜力，但在腹部成像中受到主磁场偏移量大的挑战，而且利用传统的非对称性分析法得到的酰胺质子转移（Amide Proton Transfer，APT）成像对比度受到核奥氏增强（Nuclear Overhauser Enhancement，NOE）效应的干扰.本文提出了一种基于神经网络拟合的CEST后处理方法，对每个像素采集得到的Z谱特征进行识别，不需要额外序列扫描即可得到背景参考Z谱与主磁场偏移量，用以校正和获得理想的Z谱，并进一步分离得到源自APT效应与NOE效应的信号.鸡蛋清和健康志愿者腹部成像结果显示，本文提出的基于神经网络的CEST后处理方法效果较好.

关键词: 磁共振成像（MRI）, 化学交换饱和转移（CEST）, 酰胺质子转移（APT）, 核奥氏增强（NOE）, 神经网络

Abstract:

Chemical exchange saturation transfer (CEST) imaging shows great potential in clinical applications. However, CEST imaging is challenging in abdomen due to the large B₀ shift. Meanwhile, the nuclear Overhauser enhancement (NOE) effect contaminates amide proton transfer (APT) image when using the conventional asymmetry analysis. In this paper, a CEST post-processing approach based on neural network fitting was proposed. Through recognizing the characteristics of acquired Z-spectrum, the background reference Z-spectrum and the B₀offset were obtained and used to correct the acquired Z-spectrum. The APT effect and NOE effect could be calculated by subtracting the background reference Z-spectrum from the acquired Z-spectrum. The proposed CEST post-processing approach was validated by the egg white imaging and the abdomen imaging on four healthy volunteers.

Key words: magnetic resonance imaging (MRI), chemical exchange saturation transfer (CEST), amide proton transfer (APT), nuclear Overhauser enhancement (NOE), neural network

中图分类号:

O482.53

王志超,张记磊,赵羽,华婷,汤光宇,李建奇. 基于神经网络拟合的腹部化学交换饱和转移成像[J]. 波谱学杂志, 2022, 39(1): 33-42.

Zhi-chao WANG,Ji-lei ZHANG,Yu ZHAO,Ting HUA,Guang-yu TANG,Jian-qi LI. CEST Imaging of the Abdomen with Neural Network Fitting[J]. Chinese Journal of Magnetic Resonance, 2022, 39(1): 33-42.

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质子池类别	生理参数类别	数值范围
自由水池	纵向弛豫率R₁/s^?1	0.5~1.3
自由水池	横向弛豫率R₂/s^?1	4~20
自由水池	化学位移	δ ?1.6~1.6
半固态大分子MT池	质子浓度分数/%	0~8
半固态大分子MT池	交换率/s^?1	19~40
半固态大分子MT池	纵向弛豫率R₁/s^?1	1.1~1.35
半固态大分子MT池	横向弛豫率R₂/s^?1	8×10⁴~1.5×10⁵

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