Uneven enhancement is slightly more pronounced in the venous phase than in the arterial phase, which means that the density of the contrast agent is not uniform within the lesion, and the density of the contrast agent is higher in the venous phase than in the arterial phase. After a lesion has occurred in the human body, examinations such as enhanced CT or enhanced MRI can be performed, which require injection of contrast medium from a vein, and then the enhancement of the lesion is observed; if the density of contrast medium within the lesion is both high and low, it is called inhomogeneous enhancement. When observing the enhancement of the lesion, it can be divided into arterial, venous, and delayed phases. In the venous phase, if the density of the contrast agent is slightly higher than that of the arterial phase, it is called the enhancement of the venous phase is slightly higher than that of the arterial phase. After a lesion occurs in a tissue or organ, the enhancement is different for different types of lesions, and the disease can be diagnosed according to the enhancement.