We describe the use of a recently developed technique in the field of color Doppler sonography, called power Doppler or color Doppler energy, that produces better images of the intracranial arteries than those obtained by conventional color Doppler techniques. Color Doppler energy makes it possible to identify aneurysms and their relationship to the parent artery, thus allowing one to observe how much of an aneurysm remains patent and the condition of adjacent arteries during endovascular treatment. We describe the use of this technique during the insertion of Guglielmi detachable coils into aneurysms and during subsequent follow-up examination.