The hypointense shadow shown by CT of the brain needs to be combined with the clinical history. If the patient has a previous history of traumatic brain injury, the hypointense shadow in the brain may be a lesion left over from the previous traumatic brain injury. If the patient presents to the clinic with a limb disorder, such as weakness of one limb, this intracerebral hypointense shadow needs to be considered as cerebral infarction. In addition, there is another condition, irregular hypointense shadow in the brain, and the intracranial occupying effect is also obvious, in this case the hypointense shadow in the brain should be considered as brain tumor. If it is found that the hypointense shadow in the brain is not clear what lesion it is, the patient will usually be advised to have further MRI. This can clarify the hypointense shadow and consider whether it is an ischemic lesion or a tumor lesion. The specific diagnosis should also be considered in conjunction with CT values and medical history.