Is Quasi-moyamoya Disease a Uniform Disease Entity? A Three-Dimensional Constructive Interference in Steady State Imaging Study

These findings strongly suggest that quasi-MMD is not a uniform disease entity and includes at least 2 pathophysiologically different groups: the arterial shrinkage group and the nonarterial shrinkage group. A certain subgroup of MMD patients may be misdiagnosed as quasi-MMD because of the patients' comorbid disorders and mixed up with the patients who present angiographic findings similar to MMD in spite of the lack of arterial shrinkage.