Zhang Xinyu, Gao Xuehua, Zhang Pengpeng, Guo Yanrong, Lin Haoming, Diao Xianfen, Liu Yingxia, Dong Changfeng, Hu Yaxin, Chen Siping, Chen Xin
School of Biomedical Engineering, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China.
Shenzhen Institute of Hepatology, The Third People's Hospital of Shenzhen, Shenzhen, China.
Med Eng Phys. 2017 Jun;44:79-86. doi: 10.1016/j.medengphy.2017.02.014. Epub 2017 Mar 9.
Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder in both developed and developing countries. A noninvasive method of detecting early stage NAFLD and distinguishing non-alcoholic steatohepatitis (NASH) from simple steatosis (SS) would be useful. The over-accumulation of fat in hepatocytes alters the physical microstructure and chemical contents of the liver tissue. This study included dynamic mechanical analysis (DMA) testing on liver samples from a rat model of NAFLD to determine whether the tissue shows any significant changes in viscoelasticity due to the histological changes. Liver steatosis was induced in 57 rats by gavage feeding of a high fat emulsion; 12 rats received a standard diet only and served as controls. Each rat provided 2 or 3 samples for DMA tests. The shear modulus and loss modulus were measured at 9 frequency points evenly-spaced in the range from 1Hz to 41Hz. The phase velocity of shear wave was calculated from the measured modulus. Multivariate T test was used to assess the significance of intra-group difference. The results showed significant changes (p < 0.05) in storage modulus in livers with moderate to severe (S2 to S4) steatosis in comparison with livers without steatosis (S0), while the loss modulus demonstrated significant changes earlier in stage S1, indicating that fat accumulation affects the mechanical properties of liver, particularly viscosity. However, no significant differences were observed between the steatosis grades. These results also suggest that mild inflammation may affect the mechanical properties, which requires further verification. These findings provide new information about the mechanical properties of livers with NAFLD in low frequency range and suggest that it is possible to distinguish normal livers from livers with NAFLD.
非酒精性脂肪性肝病（NAFLD）是发达国家和发展中国家最常见的肝脏疾病。一种检测早期NAFLD并区分非酒精性脂肪性肝炎（NASH）与单纯性脂肪变性（SS）的非侵入性方法将很有用。肝细胞中脂肪的过度积累会改变肝组织的物理微观结构和化学成分。本研究对NAFLD大鼠模型的肝脏样本进行了动态力学分析（DMA）测试，以确定由于组织学变化，该组织的粘弹性是否有任何显著变化。通过灌胃高脂乳剂诱导57只大鼠发生肝脂肪变性；12只大鼠仅接受标准饮食作为对照。每只大鼠提供2或3个样本用于DMA测试。在1Hz至41Hz范围内均匀分布的9个频率点测量剪切模量和损耗模量。根据测量的模量计算剪切波的相速度。采用多变量T检验评估组内差异的显著性。结果显示，与无脂肪变性（S0）的肝脏相比，中度至重度（S2至S4）脂肪变性的肝脏储能模量有显著变化（p < 0.05），而损耗模量在S1期更早出现显著变化，表明脂肪积累会影响肝脏的力学性能，尤其是粘度。然而，脂肪变性等级之间未观察到显著差异。这些结果还表明，轻度炎症可能会影响力学性能，这需要进一步验证。这些发现提供了关于NAFLD肝脏在低频范围内力学性能的新信息，并表明有可能区分正常肝脏和NAFLD肝脏。
