Abstract
MR angiography (MRA) has been rapidly developed as a clinically useful modality. We present our experiences with MRA in the diagnosis and surgical treatment of Moyamoya disease.
We have examined patients with Moyamoya disease using a 1.5 T MR unit (Signa, GE). The findings were analyzed in comparison with those of conventional cerebral angiography. A 0.5 T MR unit (Gyroscan, Phillips) was also used in some cases to compare MRA findings under different magnetic field strength. 3-D Time-of-Flight (3D-TOF) imaging was very sensitive in detecting steno-occlusive changes at the supraclinoid portion of the internal carotid artery and/or the origins of the anterior and middle cerebral arteries. There was, however, a tendency to overestimate the stenotic changes. In half the cases, it was difficult to visualize Moyamoya vessels clearly. 2D-TOF imaging detected the Moyamoya vessels better than 3D-TOF. MRI, which shows the Moyamoya vessels in the basal ganglia as flow void, is also helpful for diagnosis. In about 90% of the cases Moyamoya disease could be diagnosed by a combination of 3D-TOF, 2D-TOF and/or MRI without angiography. MRA at 0.5 T also detected the steno-occlusive lesions but its overestimation was more than that by 1.5T unit. Postoperative collateral formation from the external carotid artery to the brain was also observed on MRA by presaturation method. MRA can be used in the follow-up study at OPD and as a screening of Moyamoya disease.
