Fatty liver, also known as hepatic steatosis, is a metabolic and functional abnormality of the liver that leads to abnormal deposition of fat in liver cells. Fatty liver typically presents characteristic features on a CT scan, generally starting with a decrease in density. The reference standard for decreased density is based on the spleen. Normally, the CT value of the liver is greater than that of the spleen. If the CT value of the liver is lower than that of the spleen, it can be diagnosed as fatty liver. Some focal fatty liver changes can also be diagnosed by CT, mainly manifested by a decrease in density in a particular lobe or segment of the liver, but the blood vessels can still be normally visualized.