Liver abscess is a purulent lesion of the liver caused by a variety of microorganisms such as bacteria, fungi or amebic protozoa. The rich ductal system in the liver, including the biliary system, portal system, hepatic arteriovenous system and lymphatic system, greatly increases the probability of microbial parasitism and infection. There are three types of liver abscesses, among which bacterial liver abscess is often a mixed infection caused by multiple bacteria, about 80%, amoebic liver abscess is about 10%, and fungal liver abscess is less than 10%. MRI manifestation】 The central region of liver abscess is T1WI low signal, T2WI high signal, T2WI central may have separation and debris, central fluid-containing pus cavity is often surrounded by several millimeters thick inflammatory liver parenchyma, abscess wall may contain microabscesses, and perifocal edema may appear. A. T2 fat suppression: wedge-shaped edematous area in the right lobe of the liver surrounding a small focal effusion; B: T1 fat suppression: low signal relative to the liver; C. T1-weighted gradient echo imaging: thick wall in the effusion area; D. Delayed phase: persistent enhancement of the abscess wall. Differential diagnosis】 ①metastatic tumor (signal reduction in the delayed phase). ②Metastatic tumor with co-infection (difficult to differentiate, based on clinical history). ③Candida hepatica infection (multiple, small). ④Encapsulated cysts (with segregation).