Zarei Sevda, Ghalichi Farzan, Ahmadlouydarab Majid
Department of Biomedical Engineering, Division of Biomechanics, Sahand University of Technology, Tabriz, Iran.
Faculty of Chemical & Petroleum Engineering, University of Tabriz, Tabriz, Iran.
Comput Biol Med. 2025 Feb;185:109585. doi: 10.1016/j.compbiomed.2024.109585. Epub 2024 Dec 26.
The liver, a vital metabolic organ, is always susceptible to various diseases that ultimately lead to fibrosis, cirrhosis, acute liver failure, chronic liver failure, and even cancer. Optimal and specific medicine delivery in various diseases, hepatectomy, shunt placement, and other surgical interventions to reduce liver damage, transplantation, optimal preservation, and revival of the donated organ all rely on a complete understanding of perfusion and mass transfer in the liver. This study aims to simulate the computational fluid dynamics of perfusion and the temporal-spatial distribution of a medicine in a healthy liver to evaluate the hemodynamic characteristics of flow and medicine transport with the purpose of more effective liver treatment.
Patient-specific geometries of parenchyma and hepatic artery, portal vein, and hepatic vein vessels of a healthy liver were segmented and reconstructed from the abdominal computed tomography scan images. Mesh was generated for the comprehensive combined model using unstructured tetrahedral elements. Transient pressure values were applied as boundary conditions at the portal vein and hepatic artery inlets, and pressure outlet boundary condition was assumed at the hepatic vein outlet. Medicine injection was done through the portal vein. The liver parenchyma was assumed to be a porous medium. Finally, computational fluid dynamics (CFD) simulation was performed to investigate blood perfusion, medicine distribution, and saturation time.
The velocity parameter values calculated for the hepatic artery, portal vein, and hepatic vein vessels were consistent with the physiological ranges. The mass flow rate was higher in the portal vein than in the hepatic artery, which was consistent with high perfusion through the portal vein. The portal pressure gradient was 8.53 mmHg. From a pharmacokinetic viewpoint, medicine distribution in porous tissue was a heterogeneous process. Medicine distribution was higher at end-diastolic pressure than at peak-systolic pressure which showed the influence of hepatic artery flow. The tissue was saturated faster at first 40 s and with decreasing porosity, saturation time decreased, and distribution improved.
The right lobe included a higher number of vascular terminals due to its larger volume, and the flow rate was higher in this lobe compared to the left lobe. This showed the significant effect of the right lobe on the overall function of the body. Recirculation flow zones along hepatic artery and portal vein branches emphasized the sensitivity of downstream vessels. Rotational flow and potential vortex formation at the hepatic vein outlet may indicate a risk of plaque and clot formation in this region. The heterogeneous distribution of medicine indicated the importance of injection time in treating liver diseases. The percentage of tissue porosity affected the saturation time, so adjusting the medicine dose and injection time could be challenging in treatments.
肝脏作为一个重要的代谢器官，总是容易受到各种疾病的影响，这些疾病最终会导致肝纤维化、肝硬化、急性肝衰竭、慢性肝衰竭，甚至癌症。在各种疾病中实现优化且特异性的药物递送、肝切除术、分流置入以及其他减少肝损伤的外科干预措施、移植、对捐赠器官的优化保存和复苏，所有这些都依赖于对肝脏灌注和传质的全面理解。本研究旨在模拟健康肝脏中灌注的计算流体动力学以及药物的时空分布，以评估血流动力学特征以及药物运输情况，从而实现更有效的肝脏治疗。
从腹部计算机断层扫描图像中分割并重建健康肝脏的实质以及肝动脉、门静脉和肝静脉血管的患者特异性几何模型。使用非结构化四面体单元为综合组合模型生成网格。将瞬态压力值作为门静脉和肝动脉入口处的边界条件，并假设肝静脉出口处为压力出口边界条件。通过门静脉进行药物注射。假设肝脏实质为多孔介质。最后，进行计算流体动力学（CFD）模拟以研究血液灌注、药物分布和饱和时间。
为肝动脉、门静脉和肝静脉血管计算得到的速度参数值与生理范围一致。门静脉中的质量流率高于肝动脉，这与通过门静脉的高灌注一致。门静脉压力梯度为8.53 mmHg。从药代动力学角度来看，药物在多孔组织中的分布是一个非均匀过程。舒张末期压力下的药物分布高于收缩期峰值压力下的分布，这显示了肝动脉血流的影响。最初40秒内组织饱和较快，随着孔隙率降低，饱和时间减少，分布得到改善。
右叶由于体积较大，包含更多的血管末梢，与左叶相比，该叶的血流速度更高。这表明右叶对身体整体功能有显著影响。沿肝动脉和门静脉分支的再循环流动区域强调了下游血管的敏感性。肝静脉出口处的旋转流和潜在涡旋形成可能表明该区域存在斑块和血栓形成的风险。药物的非均匀分布表明注射时间在肝脏疾病治疗中的重要性。组织孔隙率百分比影响饱和时间，因此在治疗中调整药物剂量和注射时间可能具有挑战性。
