ADC refers to Apparent Diffusion Coefficient, which is a magnetic resonance term used in imaging. A low signal ADC map means that the diffusion of water molecules in the area is limited, and when analyzed in combination with diffusion diffusion imaging (DWI), it often suggests that there is a lesion in the area, which is commonly seen in the early stage of cerebral infarction, abscesses, and malignant tumors. The DWI (diffusion-weighted sequence) image of the patient can be obtained from the MRI scan, and the computer can calculate the DWI to generate an ADC map, which, like the DWI map, is used to depict the speed of diffusion of the water molecules in the tissue structure, i.e., the speed of the movement of the water molecules. When the dispersion of water molecules is limited, the ADC map tends to be low signal; when the dispersion of water molecules is not limited, the ADC map tends to be high signal. In diagnostic imaging, many diseases or lesions will show restricted water molecule dispersion. If the ADC shows low signal in the imaging report, it is recommended to listen to the judgment of the imaging department or clinical department doctors according to the patient’s specific condition, and do not make decisions on your own to avoid delaying the condition.