Hypodense lesions in the liver are seen in the following diseases: first, simple hepatic cysts, which are congenital developmental abnormalities and are associated with bile duct dilatation. Many patients do not have clinical manifestations but are found during health check-ups, so this condition also does not require special treatment and can be reviewed regularly. Second, it can be an occupying lesion of the liver, commonly known as liver tumor, and malignant tumor is also more common. The cause of occurrence is related to viral hepatitis or alcoholic cirrhosis caused by years of alcohol consumption, secondary to which the patient will also experience pain in the liver area and weakness, loss of appetite or accompanied by weight loss, and the evolution of the disease will also appear abnormal liver function. In primary malignant lesions of the liver, methemoglobin measurements may be significantly increased.