Stagnant thinking means that the association is not easily developed, showing obvious inertia and always dwelling on the same problem. For the examination of thought stagnation, the commonly used imaging examinations are CT, MRI, PET, EEG, etc. 1. Structural imaging Used to rule out other underlying diseases and to detect specific imaging manifestations of AD. Head CT (thin-section scanning) and MRI (coronal) examinations can show significant cortical atrophy, especially in the hippocampus and medial temporal lobe, supporting the clinical diagnosis of AD. Compared with CT, MRI is more sensitive to detect subcortical vascular changes (e.g., infarcts at critical sites) and changes suggestive of specific diseases (e.g., multiple sclerosis, progressive supranuclear palsy, multisystem atrophy, corticobasal ganglion degeneration, prion disease, frontotemporal dementia, etc.). 2. Functional neuroimaging Such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) can improve the confidence of dementia diagnosis. 18F-deoxyribose glucose positron emission tomography (18FDG-PET) can show decreased glucose metabolism in the temporoparietal and superior/posterior temporal regions, posterior cingulate cortex, and precuneus, revealing specific abnormal changes in AD. tool, especially for the differential diagnosis of AD from other dementias. Amyloid PET imaging is a very promising technique, but it is not yet routinely used. 3. Electroencephalography (EEG) The EEG of AD is characterized by decreased alpha waves, increased theta waves, and decreased mean frequency. However, 14% of patients have normal EEG in the early stages of the disease.EEG is used in the differential diagnosis of AD and may provide early evidence of prion disease or suggest the possible presence of toxic-metabolic abnormalities, transient epileptic amnesia, or other epileptic disorders.