The diagnostic accuracy of time-of-flight MR angiography in diagnosing Moyamoya disease

Conventional cerebral angiography is essential for achieving the diagnosis of Moyamoya disease. It is, however, an invasive examination, especially for the pediatric patients. In this paper, we report on the results of an investigation as to whether MRA is able to accurately visualize the steno-occlusive changes in the carotid fork and the basal moyamoya vessels less invasively. Twenty patients among them, 16 children who were diagnosed as having Moyamoya disease with conventional angiography underwent MRI and MRA using a 1.5T MR unit (Signa, G.E.). Angiographically, 37 sides were determined to be in stage 3. MRA was performed using two-dimensional time-of-flight (2D-TOF), 3D-TOF, and gadolinium (Gd)-enhanced 3D-TOF methods. The 3D-TOF MRAs showed almost equal sensitivity to that of conventional angiography for the detection of steno-occlusive changes in the carotid fork. However, it was difficult to visualize the moyamoya vessels clearly. Further, 3D-TOF, 2D-TOF, and Gd-enhanced 3D-TOF methods depicted the moyamoya vessels in 65%, 79%, and 80% of the examined sides, respectively. In contrast, MRI visualized the moyamoya vessels as multiple flow voids in the basal ganglia in 38 of 40 sides (95%). Based on the above findings, it was thus concluded that approximately 90% of the stage 3 Moyamoya disease cases could be diagnosed by a combination of 3D-TOF MRA and MRI without the use of conventional angiography. (author)