Yin Meng, Glaser Kevin J, Manduca Armando, Mounajjed Taofic, Malhi Harmeet, Simonetto Douglas A, Wang Ruisi, Yang Liu, Mao Shennen A, Glorioso Jaime M, Elgilani Faysal M, Ward Christopher J, Harris Peter C, Nyberg Scott L, Shah Vijay H, Ehman Richard L
From the Departments of Radiology (M.Y., K.J.G., A.M., R.L.E.) and Physiology and Biomedical Engineering (A.M.) and the Divisions of Anatomic Pathology (T.M.), Gastroenterology and Hepatology (H.M., D.A.S., R.W., L.Y., V.H.S.), Transplantation Surgery (S.A.M., J.M.G., F.M.E., S.L.N.), and Nephrology and Hypertension (C.J.W., P.C.H.), Mayo Clinic, 200 First St SW, Rochester, MN 55905.
Radiology. 2017 Sep;284(3):694-705. doi: 10.1148/radiol.2017160622. Epub 2017 Jan 27.
Purpose To investigate the utility of magnetic resonance (MR) elastography-derived mechanical properties in the discrimination of hepatic inflammation and fibrosis in the early stages of chronic liver diseases. Materials and Methods All studies were approved by the institutional animal care and use committee. A total of 187 animals were studied, including 182 mice and five pigs. These animals represented five different liver diseases with a varying combination and extent of hepatic inflammation, fibrosis, congestion, and portal hypertension. Multifrequency three-dimensional MR elastography was performed, and shear stiffness, storage modulus, shear loss modulus, and damping ratio were calculated for all animals. Necroinflammation, fibrosis, and portal pressure were either histologically scored or biochemically and physically quantified in all animals. Two-sided Welch t tests were used to evaluate mean differences between disease and control groups. Spearman correlation analyses were used to evaluate the relationships between mechanical parameters and quantitative fibrosis extent (hydroxyproline concentration) and portal pressure. Results Liver stiffness and storage modulus increased with progressively developed fibrosis and portal hypertension (mean stiffness at 80 Hz and 48-week feeding, 0.51 kPa ± 0.12 in the steatohepatitis group vs 0.29 kPa ± 0.01 in the control group; P = .02). Damping ratio and shear loss modulus can be used to distinguish inflammation from fibrosis at early stages of disease, even before the development of histologically detectable necroinflammation and fibrosis (mean damping ratio at 80 Hz and 20-week feeding, 0.044 ± 0.012 in the steatohepatitis group vs 0.014 ± 0.008 in the control group; P < .001). Damping ratio and liver stiffness vary differently with respect to cause of portal hypertension (ie, congestion- or cirrhosis-induced hypertension). These differentiation abilities have frequency-dependent variations. Conclusion Liver stiffness and damping ratio measurements can extend hepatic MR elastography to potentially enable assessment of necroinflammatory, congestive, and fibrotic processes of chronic liver diseases. RSNA, 2017 Online supplemental material is available for this article.
目的 探讨磁共振（MR）弹性成像得出的力学特性在鉴别慢性肝病早期肝炎症和纤维化中的作用。材料与方法 所有研究均获机构动物护理与使用委员会批准。共对187只动物进行了研究，包括182只小鼠和5头猪。这些动物代表了五种不同的肝病，伴有不同组合和程度的肝脏炎症、纤维化、充血和门静脉高压。进行了多频三维MR弹性成像，并计算了所有动物的剪切刚度、储能模量、剪切损耗模量和阻尼比。对所有动物的坏死性炎症、纤维化和门静脉压力进行了组织学评分或生化及物理定量。采用双侧韦尔奇t检验评估疾病组与对照组之间的平均差异。采用斯皮尔曼相关性分析评估力学参数与定量纤维化程度（羟脯氨酸浓度）和门静脉压力之间的关系。结果 肝脏硬度和储能模量随着纤维化和门静脉高压的逐渐发展而增加（脂肪性肝炎组在80Hz和喂养48周时的平均硬度为0.51kPa±0.12，而对照组为0.29kPa±0.01；P = 0.02）。阻尼比和剪切损耗模量可用于在疾病早期区分炎症和纤维化，甚至在组织学上可检测到的坏死性炎症和纤维化出现之前（脂肪性肝炎组在80Hz和喂养20周时的平均阻尼比为0.044±0.012，而对照组为0.014±0.008；P < 0.001）。阻尼比和肝脏硬度因门静脉高压的原因（即充血性或肝硬化性高血压）而异。这些区分能力具有频率依赖性变化。结论 肝脏硬度和阻尼比测量可扩展肝脏MR弹性成像，从而有可能评估慢性肝病的坏死性炎症、充血性和纤维化过程。RSNA，2017 本文提供在线补充材料。
