Smoldering disease is a Willis ring chronic progressive occlusive disease with a long course. The clinical manifestations vary in different stages due to the extent and degree of vascular involvement, and thus its clinical manifestations are complex and diverse, which can be simply divided into hemorrhagic and ischemic types, the former including subarachnoid hemorrhage, parenchymal hemorrhage, and ventricular hemorrhage, and the latter including TIA, cerebral infarction, headache, dizziness, epilepsy, and mental retardation. In patients with the hemorrhagic type, clinicians often look for vascular factors to confirm the diagnosis. In children with ischemic type, the typical presentation is episodic numbness and weakness of one limb or hemiparesis after hyperventilation or exercise, and such patients are not easy to miss the diagnosis, but if there are only symptoms such as blurred vision, headache, dizziness, limb twitching and mental retardation, and the clinician lacks sufficient knowledge of the disease, it is difficult to think of looking for the cause from vascular factors. Therefore, for pediatric patients with the above clinical manifestations, if no other clear cause is found, the possibility of the disease should be considered. In adult ischemic patients, in addition to the above-mentioned reasons for underdiagnosis, patients with TIA and cerebral infarction are often simply diagnosed as atherosclerotic cerebral thrombosis. In fact, smog disease has certain characteristic changes on plain CT and MRI. The progressive occlusion of the skull base arteries in patients with smoldering disease leads to the formation of extensive intracranial and extracranial and cortical collateral branches, resulting in changes in the extent of blood supply to the major cerebral arteries, so that the lesions of cerebral infarction in some patients do not correspond to the extent of cerebral artery distribution. In addition, the smoke-like vessels at the base of the brain and the brain parenchyma show more vascular flow hollow shadow in T1 and T2 phases; while the dilated cortical soft meningeal arteries show the characteristic “ivy sign” on FLAIR sequences: dotted or thin striped high signal and dotted or thin striped enhancement shadow in T1 enhancement phase, like crawling ivy on a stone. Ivy. The possibility of smog should also be considered for those with these imaging findings. In addition to enabling the clinician to think of “smog”, a noninvasive cerebrovascular examination is a decisive factor in improving the diagnosis of smog. As mentioned above, the patient’s clinical presentation as well as general CT and MRI may provide informative values such as abnormal basal vascular flow, but in many cases only suggest ischemic or hemorrhagic lesions, so it is especially important to choose further noninvasive cerebrovascular examinations. In combination with our national situation, the inexpensive TCD test is preferred in screening for smog. The sensitivity, specificity, and accuracy of MRI+MRA are 92%, 100%, and 94%, respectively, when major arterial stenosis or occlusion and lateral branch compensatory TCD changes are detected. Stenosis or occlusion of the beginning segment of the artery; smoke-like abnormal vascular network visible in the basal ganglia area; lesions are bilateral. In fact, it is not difficult to improve the diagnosis rate of smoldering disease, as long as we think about it, and then perform TCD screening or MRI examination together with MRA examination, we can avoid a large proportion of patients from being missed or misdiagnosed.