基于灌注和代谢功能磁共振成像TIPS术后脑的适应性机制及肝性脑病预警研究

Treatment with a transjugular intrahepatic portosystemic shunt (TIPS) is highly effective in the control of portal hypertension in cirrhotic patients. However, hepatic encephalopathy (HE) is a common complication after the TIPS procedure. The morbidity and mortality of post-TIPS HE is high in cirrhotic patients 1-3 months after the TIPS placement, which strongly affects the outcome of patients. Also, it restricts the clinical usage of TIPS. The TIPS procedure can induce not only hemodynamic changes, but also elevate the concentration of neurotoxins (specially ammonia level). In this proposal, we suppose that post-TIPS HE is related to cerebral adaptations to hemodynamic changes and to elevated neurotoxin based on cerebral adaptability theory. To verify such a hypothesis, we aim to comprehensively study the cerebral adaptability based on perfusion and metabolism functional MRI. We will modulate cerebral blood flow to study the post-TIPS mechanism of cerebral adaptability to hemodynamic changes. Also, we will assess the relationships among by-passed ammonia, cerebral ammonia delivery, and cerebral metabolic rate of ammonia to the post-TIPS mechanism of cerebral adaptability to changes in ammonia. We hope that our findings about the mechanisms of cerebral adaptability could be used to predict post-TIPS HE.

经颈静脉门体分流术（transjugular intrahepatic portosystemic shunt,TIPS）是治疗肝硬化门脉高压的有效手段之一。然而， TIPS术后1-3个月间肝性脑病发病率和死亡率较高，限制了TIPS术在临床的更广泛应用。由于TIPS术后不仅血流动力学发生改变，而且分流后神经毒素(特别是氨)水平上升，所以根据TIPS术后脑的适应性理论，推断术后肝性脑病发生与脑对血流动力学改变和对毒素的适应能力有关。为此，拟基于灌注和代谢功能磁共振技术，通过肝－脑一体化系统地研究脑对TIPS术的适应性机制。拟通过调制脑血流波动模拟TIPS术对脑的血流动力学发生改变，研究脑对血流动力学改变的的适应性机制；拟分析支架的分流氨量、脑氨递送和脑氨代谢间的关系，研究脑对氨的适应性机制。预期通过研究TIPS术后肝性脑病发生与脑的适应性机制间关系，为肝性脑病预警提供可行方案。

肝性脑病是经颈静脉门体分流术（transjugular intrahepatic portosystemic shunt,TIPS）的主要并发症且死亡率较高，限制了TIPS术在临床的更广泛应用。本项目基于灌注和代谢功能磁共振技术，通过肝－脑一体化系统地研究脑对TIPS术的适应性机制。研究结果显示病人的全脑血流量先增加后下降，氧摄取分数在肝硬化病人中上升，且维持在一个高水平，肝硬化无脑病和隐匿性肝性脑病组的病人全脑氧代谢维持在正常水平，而临床型肝性脑病组病人的氧代谢显著下降。研究结果支持肝性脑病发生与脑的适应性机制间关系，为肝性脑病预警提供可行方案。