Gastroesophageal varices, the most relevant portal-system collaterals, and acute variceal bleeding are critical complications that result directly from portal hypertension in patients with cirrhosis. Gastroesophageal varices are present approximately in 50% of patients with cirrhosis. Their presence correlates with the severity of liver disease. Only 40% of Child-Pugh A patients have varices whilst 85% of the occurrence rate in Child-Pugh C patients. Due to remarkable improvements in diagnostic and therapeutic modalities such as vasoactive agents, endoscopic therapy and antibiotics, the overall prognosis has been improved during the past several decades. However, it is still associated with increased mortality, which is still around 20% at 6 weeks. Acute variceal bleeding is also responsible for a variety of other complications in patients with cirrhosis including acute on chronic liver failure, hepatorenal syndrome, ascites liquid infection and hepatic encephalopathy. Therefore, timely and effective control of acute variceal bleeding is of crucial importance for the prognosis in patients with cirrhosis.

In the early stages of cirrhosis, when portal hypertension is moderate, increased cardiac output compensated for a modest reduction in the systemic vascular resistance, ensuring the arterial pressure and effective arterial blood volume to maintain within the normal limits. Patients with advanced cirrhosis have an intense overactivity of the endogenous vasoactive systems characterized by arterial hypotension and low peripheral vascular resistance. This cascade of events sets the stage for further renal vasoconstriction and renal sodium retention as the splanchnic and systemic vasodilatation worsens with the progression of cirrhosis. Severe renal vasoconstriction in consequence of marked arterial vasodilatation in splanchnic circulation triggers the reduction of glomerular filtration rate, and thus induces acute kidney injury (AKI)/ hepato-renal syndrome (HRS) which may implicate in the increasing mortality in patients with cirrhosis.

Renal functional magnetic resonance imaging (fMRI), a technique considered superior to the most common method used to estimate the glomerular filtration rate, allows for non-invasive, accurate measurements of renal structures and functions in both animals and humans. It has become increasingly prevalent in research and clinical applications. In recent years, renal fMRI has developed rapidly with progress in MRI hardware and emerging post-processing algorithms. Function related imaging markers could be acquired via renal fMRI, encompassing water molecular diffusion, perfusion, and oxygenation. The study will use phase contrast - MR angiography, intravoxel incoherent motion - diffusion weighted imaging (IVIM-DWI) and blood-oxgen-level-dependent (BOLD)-MRI to evaluate renal functional changes after using vasoactive medications in patients with cirrhosis.

The rationale for the use of vasoactive medications, including terlipressin and octreotide, is to produce splanchnic vasoconstriction and reduce portal blood flow and portal pressure, thereby underpinning the application of these vasoactive drugs in the management of cirrhotic patients with acute variceal bleeding. Meanwhile, terlipressin has been recommended as the international first-line pharmacological therapy for the treatment of HRS because terlipressin may improve renal hemodynamics, improve renal function in patients and potentially enable HRS a reversible condition without the need of liver transplantation. However, the renal protection effect of terlipressin vs. octreotide remains unknown. In this study, the investigators aim to conduct a multicenter, single-blind randomized controlled trial to compare the renal protection effect of terlipressin vs. octreotide assessed by fMRI in the management of cirrhotic patients with acute variceal bleeding.