Bilateral middle cerebral arteries that are not clearly visualized on cranial vascular magnetic resonance or angiography may be due to stenosis or occlusion of the proximal middle cerebral artery or distal internal carotid artery, which may result in poor passage of blood flow or contrast medium. This may be due to congenital malformation of the proximal middle cerebral artery or distal internal carotid artery, atheromatous plaque formation, cardiogenic thromboembolism (e.g., congenital patent foramen ovale, atrial fibrillation, etc.), blood clotting, aneurysm, or entrapment, resulting in stenosis or hemodynamic abnormality, and inability to visualize the middle cerebral arteries bilaterally, or poor visualization. Narrowing or hemodynamic abnormality of intracranial arteries can easily lead to cerebrovascular diseases such as cerebral infarction, which can be life-threatening. Once the imaging test shows abnormalities of bilateral middle cerebral arteries, it is necessary to actively cooperate with doctors for further examination or treatment to prevent cardiovascular and cerebrovascular accidents or aggravation of the condition.