What does brain lesion mean?

Brain lesion is a broad term without specificity. It refers to any brain injury that causes cell necrosis in the brain and can be observed by imaging examination. It is usually abnormal density or abnormal signal found in the brain during CT or MRI examination. As long as it is abnormal, it is called brain lesion. There are many causes of brain lesion, and different diseases can be found in different ages. Take the elderly as an example, cerebrovascular disease is the most common, cerebral infarction and cerebral hemorrhage can cause brain cell necrosis, local soft focus, filled with cerebrospinal fluid and glial cells, etc., showing low density shadow on CT, long T1 and long T2 signal on MRI. Brain tumors also suggest brain lesions, which can be high density or mixed density on CT, or even isodensity, and can also be high and low signals on MRI. In addition, brain contusion or encephalitis can cause necrosis of brain cells and cause lesion formation.