Wang Yi Xiang J, Huang Hua, Zheng Cun-Jing, Xiao Ben-Heng, Chevallier Olivier, Wang Wei
Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong New Territories, Hong Kong SAR, China.
Department of Radiology, The Third People's Hospital of Shenzhen, The Second Affiliated Hospital of Southern University of Science and Technology, National Clinical Research Center for Infectious Diseases Shenzhen, Guangdong Province, China.
Am J Nucl Med Mol Imaging. 2021 Apr 15;11(2):107-142. eCollection 2021.
Diffusion-weighted imaging (DWI) is sensitive to the mobility of water molecule at cellular and macromolecular level, much smaller than the spatial resolution of the images. It is commonly based on single shot echo-planar imaging sequence with the addition of motion-probing gradient pulses and fat suppression. DWI is increasingly incorporated into routine body magnetic resonance imaging protocols. However, the liver is particularly affected by physiological motions such as respiration; the left liver is also affected by cardiac motion artifacts and susceptibility artefact due to contents in the stomach. Intravoxel incoherent motion (IVIM) DWI data analysis requires high-quality data acquisition using multiple -values and confidence in the measurements at low -values. This article reviews the technical developments of DWI and its applications in the liver. Challenges and some solutions for the quantification of apparent diffusion coefficient and intravoxel incoherent motion are discussed. Currently, acquisition protocols vary between research groups; patient preparation and data post-processing are not standardized. Increased standardization, both in data acquisition and in image analysis, is imperative so to allow generation of reliable DW-MRI biomarker measures that are broadly applicable.
扩散加权成像（DWI）对细胞和大分子水平上水分子的移动性敏感，其比图像的空间分辨率小得多。它通常基于单次激发回波平面成像序列，并添加运动探测梯度脉冲和脂肪抑制。DWI越来越多地被纳入常规体部磁共振成像协议中。然而，肝脏特别容易受到诸如呼吸等生理运动的影响；左肝还受到心脏运动伪影以及胃内容物引起的敏感性伪影的影响。体素内不相干运动（IVIM）DWI数据分析需要使用多个值进行高质量的数据采集，并对低值测量有信心。本文综述了DWI的技术发展及其在肝脏中的应用。讨论了表观扩散系数和体素内不相干运动量化的挑战及一些解决方案。目前，不同研究组之间的采集协议各不相同；患者准备和数据后处理也未标准化。在数据采集和图像分析方面提高标准化势在必行，以便能够生成广泛适用的可靠的DW-MRI生物标志物测量值。
