Title: Influence of portal vein occlusion on portal flow and liver elasticity in an animal model Show Chinese title

Title: 门静脉阻断对动物模型中门静脉血流和肝脏弹性的影响

Abstract: Hepatic fibrosis causes an increase in liver stiffness, a parameter measured by elastography and widely used as a diagnosis method. The concomitant presence of portal vein thrombosis (PVT) implies a change in hepatic portal inflow that could also affect liver elasticity. The main objective of this study is to determine the extent to which the presence of portal occlusion can affect the mechanical properties of the liver and potentially lead to misdiagnosis of fibrosis and hepatic cirrhosis by elastography. Portal vein occlusion was generated by insertion and inflation of a balloon catheter in the portal vein of four swines. The portal flow parameters peak flow (PF) and peak velocity magnitude (PVM) and liver mechanical properties (shear modulus) were then investigated using 4D-flow MRI and MR elastography, respectively, for progressive obstructions of the portal vein. Experimental results indicate that the reduction of the intrahepatic venous blood flow (PF/PVM decreases of 29.3%/8.5%, 51.0%/32.3% and 83.3%/53.6%, respectively) measured with 50%, 80% and 100% obstruction of the portal vein section results in a decrease of liver stiffness by $0.8\%\pm0.1\%$, $7.7\%\pm0.4\%$ and $12.3\%\pm0.9\%$, respectively. While this vascular mechanism does not have sufficient influence on the elasticity of the liver to modify the diagnosis of severe fibrosis or cirrhosis (F4 METAVIR grade), it may be sufficient to attenuate the increase in stiffness due to moderate fibrosis (F2-F3 METAVIR grades) and consequently lead to false-negative diagnoses with elastography in the presence of PVT. Show Chinese abstract

Abstract: 肝纤维化导致肝脏僵硬度增加，这是一个通过弹性成像测量的参数，被广泛用作诊断方法。门静脉血栓形成（PVT）的同时存在意味着门静脉流入的变化，这可能也会影响肝脏的弹性。本研究的主要目的是确定门静脉阻塞的存在在多大程度上会影响肝脏的机械特性，并可能导致通过弹性成像误诊肝纤维化和肝硬化。通过在四只猪的门静脉中插入并充气球囊导管来生成门静脉阻塞。然后分别使用4D流动MRI和磁共振弹性成像，对门静脉进行逐步阻塞时的门静脉流量参数峰值流量（PF）和峰值速度大小（PVM）以及肝脏机械特性（剪切模量）进行了研究。实验结果表明，门静脉部分阻塞50%、80%和100%时测得的肝内静脉血流减少（PF/PVM分别减少29.3%/8.5%、51.0%/32.3%和83.3%/53.6%），导致肝脏僵硬度分别降低$0.8\%\pm0.1\%$、$7.7\%\pm0.4\%$和$12.3\%\pm0.9\%$。虽然这种血管机制对肝脏弹性的影响力不足以改变严重肝纤维化或肝硬化的诊断（F4 METAVIR分级），但它可能足以减弱中度肝纤维化（F2-F3 METAVIR分级）引起的僵硬度增加，从而在存在PVT的情况下导致弹性成像的假阴性诊断。