CT hypointense shadow is not always a tumor, it may also be a cyst or a tumor, which needs to be combined with clinical symptoms and relevant laboratory tests. Enhanced CT can be done to clarify what lesion the hypointense shadow tends to be. For example, if a hypointense lesion on the liver is shown to be hypointense on plain scan, but, after enhancement, there will be nodular enhancement around the lesion in the arterial phase, enlargement in the venous phase and gradual inward filling, and the basic lesion is filled in the delayed phase with relative hypointense or high density, it is considered to be a hemangioma, which is a benign lesion. However, if it is simply a cyst on the liver, there is no enhancement, and it is hypointense in the plain phase, arterial phase and venous phase, so hypointense is not necessarily a tumor, and it is better to do enhanced CT to clarify whether it is a tumor.