Radiological Characteristics in Moyamoya Disease


1.Cerebral Angiography

Cerebral angiography used to be the gold standard diagnostic method.
Although it provides valuable information, less invasive method such as MRI (MRA) is sufficient enough if used only for diagnostic purposes.
Typically, narrowing internal carotid artery and middle cerebral artery are observed in bilateral hemisphere.
In response to the arterial narrowing, Moyamoya vessels (net like vessels at the base of the brain) begin to develop.



MRI can detect acute brain damage from stroke. The figure below was taken when the patient was referred to the hospital and it illustrates the small cerebral infarction. MRA is useful for both the diagnosis and for the follow-up of the patients. The stenosis of the artery can progress during the follow-up period, therefore patients usually require repeated radiological examinations.





Both SPECT and PET show the amount of cerebral blood flow. It is very important to note that the amount of blood flow cannot be assessed by the severity of the stenosis on angiography. Therefore, we need to examine cerebral blood flow directly. Another important point is that cerebral blood flow can be normal in natural condition yet it can reduce dramatically at critical level. Because it is difficult and harmful to force crying (hyperventilation) for those who have moyamoya disease, we usually use vasodilator (acetazolamide) to enhance the abnormality on imaging. Patients with positive test results generally are the good candidates for the surgery.