Smog is a relatively rare cerebrovascular disease, which was poorly understood by most people and even a small number of medical professionals for a long period of time. Imaging plays an important role in the diagnosis and treatment of smog. Various imaging methods and their significance in the perioperative period of smog disease: 1. The significance of cerebrovascular imaging: it is used to clarify the diagnosis, the degree of vascular stenosis and collateral circulation. It mainly includes DSA, MRA and CTA, among which DSA (also known as whole brain angiography) is the gold standard for the diagnosis of smog disease and can reflect the condition of cerebral vessels comprehensively. 2. Cerebral perfusion imaging: It can reflect the hemodynamic and metabolic conditions from the microcirculation level, and can make an objective assessment of the severity of the disease. The main perfusion imaging includes MRI, CT perfusion and ECT, etc. 3.High-resolution MRI: It can examine the stenosis of the affected vessels and the presence of plaque in the vessel wall. 4.Transcranial ultrasound Doppler (TCD): Transcranial ultrasound Doppler is a non-invasive, low-risk and inexpensive test that can evaluate the intracranial vascular condition and the effect of surgery in a non-invasive way; TCD is non-invasive, painless and inexpensive for patients; the test is more comprehensive, repeatable and reliable, and it can perform real-time dynamic observation and long-term dynamic monitoring; the instrument is small and easy to examine, and it has good complementarity with cerebral angiography. The instrument is small, easy to examine, and has good complementarity with cerebral angiography. It can provide important hemodynamic information that cannot be measured by MRI, DSA/SPECT and other imaging techniques. Therefore, it has important significance in the evaluation of cerebrovascular disorders and differential diagnosis. 5.CT is used for postoperative judgment: whether there is new intracranial infarction and hemorrhage in patients with smog, to assess the level of postoperative recovery and to guide the later treatment and care.