Positron emission tomography (PET) is sensitive in showing early functional or metabolic abnormalities in lesions and is particularly suitable for detecting early tumor lesions in complex anatomical structures. the principle of PET-CT is to use the physicochemical properties of certain substances to make physiological metabolic changes in the body into images that can be relatively quantified. PET and PET/CT are used to address brain disorders that patients suffer from. 1.Localization of epileptic foci and assessment of surgical efficacy: It helps to localize epileptic foci and provides reference for brain surgery. the match rate between PET/CT and traumatic cranial cortical EEG for locating epileptic foci is over 90%, providing a new non-invasive option for locating epileptic foci. epileptic foci resection under the guidance of PET/CT localization can be controlled in most patients after surgery. 2. Early diagnosis of dementia: Dementia lacks effective treatment, but some patients can improve their symptoms or slow down the progression of the disease through appropriate treatment if detected early. Therefore, early diagnosis of dementia by PET/CT is of great significance to patients, families and society. It can also identify progeria and vascular dementia. 3. Application in cerebrovascular diseases: early localization, efficacy evaluation and prognosis judgment of transient ischemic attack (TIA) and cerebral infarction.