肝移植已成为终末期肝病患者最有效的治疗手段。但肝移植手术复杂程度高，术后并发症常难以避免。随着新型免疫抑制剂的使用，术后感染已成为肝移植术后最常见的并发症。除供体、受者及术者因素外，肝移植术后感染的发生与患者营养状况关系密切，但临床常用的体重、白蛋白等指标受肝功能影响较大，有时不能真实反映患者营养状况。本论文通过阅读文献和观察临床病例，总结肝移植术后相关并发症的CT表现，提高对于肝移植术后并发症的诊断与识别能力。同时使用CT体成分分析法对肝移植患者进行研究，探索基于CT定量体成分分析法测量脂肪分布对于肝移植术后感染的预测价值，以期为临床决策提供帮助。本论文的主要内容包括：1．对肝移植术后并发症的防治现状进行文献调研，依照术后并发症的不同类型进行系统性综述，聚焦于肝移植术后感染、肝血管源性及肝实质并发症，并展开相关内容的总结与研究。2．对肝血管源性并发症及肝实质并发症的CT表现进行总结。肝移植术后肝动脉、门静脉及下腔静脉血管狭窄主要以吻合口的狭窄为主，导致狭窄的主要原因有手术操作、吻合口血管管径不匹配、急慢性排斥反应等。肝动脉及门静脉血栓形成在CTA上主要表现为血管管腔内不规则充盈缺损，管腔相对变窄甚至完全闭塞。肝动脉瘤在CTA上主要表现为肝动脉管壁局部瘤样膨出。肝移植术后早期出现肿瘤复发的患者CT可表现为移植肝内动脉期多发明显强化结节、边界清晰，门脉期、延迟期强化减低，呈典型“快进快出”表现，并可见延迟强化包膜。对于肝移植术后中晚期出现肿瘤复发的患者CT多表现为移植肝内多发类圆形低密度影，边界清晰，增强扫描可见边缘强化。移植肝实质缺血在CT上表现为包膜下肝实质片状低密度影，边界清晰，可单发也可多发融合成片，增强扫描呈轻度强化。肝脓肿的CT表现为移植肝内见片状低密度影，边界清晰，病变内可见气液平面，增强扫描脓肿壁可见强化。3．在基于CT的体成分分析对肝移植术后感染的预测价值的研究中，结果显示：肝移植患者术前皮下脂肪指数及肌肉指数的减低可能会增加术后感染的发生风险；患者术前L3椎体水平横断面的内脏脂肪面积与皮下脂肪面积的比值可作为预测肝移植术后感染发生的危险因素。

Liver transplantation has become the most effective therapy for the patients with end-stage liver disease. But postoperative complications are often difficult to avoid due to the high complexity of liver transplantation. With the introduction of novel immunosuppressive drugs, postoperative infection has become the most common complication after liver transplantation. The likelihood of postoperative infection following liver transplantation is closely related to patient nutrition, in addition to donor, recipient, and operator factors. However, commonly used clinical indicators like weight and serum albumin are greatly influenced by liver function, and sometimes do not accurately reflect patient nutrition. This thesis summarizes the CT manifestations of post-liver transplantation-related complications by reading the literature and observing clinical cases to improve the diagnosis and identification of post-liver transplantation complications. We also used CT-based body composition analysis to study liver transplant patients and explore the predictive value of measuring fat distribution based on CT quantitative body composition analysis for post-liver transplant infection, in order to provide help for clinical decision making. The main work and contributions of the paper include:1. After conducting a literature survey on the prevention and treatment of postoperative complications of liver transplantation, we conducted a systematic review according to the different types of postoperative complications, focusing on postoperative infections, hepatic vascular origin and parenchymal complications of liver transplantation, and conducted a summary and study of the relevant contents.2. The CT manifestations of hepatic vascular original complications and liver parenchymal complications were summarized. Stenosis of the hepatic artery and portal vein, after liver transplantation is mainly dominated by stenosis of the anastomosis. The main causes of stenosis are surgical operation, mismatch of anastomotic vessel diameters, acute and chronic rejection reactions. Hepatic artery and portal vein thrombosis on CTA mainly shows irregular filling defects in the lumen of the vessel, and relative narrowing or even complete occlusion of the lumen. Hepatic artery aneurysm is mainly manifested as localized aneurysmal expansion of the hepatic artery wall on CTAThe CT presentation of patients with tumor recurrence after liver transplantation can be multiple distinctly enhanced nodules with clear borders in the arterial phase of the transplanted liver, and reduced enhancement in the portal phase and delayed phase, with typical " fast in and fast out" presentation, and delayed enhancement envelope can be seen. In addition, patients with recurrent tumor may also show multiple round-like hypodense shadows with clear borders in the transplanted liver, and marginal enhancement can be seen in the enhanced scan.Ischemia of the transplanted liver parenchyma mainly appears on CT as a lamellar hypodense shadow of the subperitoneal liver parenchyma with clear borders, which can be single or multiple fused into a single patch, and mild enhancement on enhancement scan. The CT manifestation of liver abscess is a lamellar hypodense shadow in the transplanted liver with slightly blurred borders, with gas-fluid planes visible in some lesions, and enhancement of the abscess wall on enhanced scan.3. The study on the predictive value of CT-based body composition analysis for postoperative infection following liver transplantation found that: decreased preoperative subcutaneous adiposity index and muscle index in liver transplant patients may increase the risk of postoperative infection; the ratio of visceral fat area to subcutaneous fat area at the level of L3 vertebrae in patients before surgery may be used as a risk factor to predict the development of postoperative infection after liver transplantation. In addition, decreased preoperative muscle index in liver transplant patients may increase the risk of postoperative mortality in patients.