[Usefulness and limitation of MR imaging and MR angiography in diagnosis of juvenile moyamoya disease].

Magnetic resonance (MR) images and MR angiograms (MRA) were studied in 20 childhood cases of moyamoya disease. Both MRI and MRA successfully demonstrated moyamoya vessels in the basal ganglia in all cases, with a positive but not definite correlation to the conventional angiographic findings. MRI depicted the stenotic and occlusive lesions of the carotid fork and horizontal portion of the middle cerebral artery effectively. MRA demonstrated some lesions which even MRI failed to prove, but it tended to overestimate the lesions. Post-operative state of collateral flow and the patency of EC-IC bypass graft could be evaluated as accurately with MRA as with conventional angiography, although MRA was limited in spatial resolution and evaluation of flow direction. In conclusion, MRI and MRA were considered to be useful in the diagnosis of moyamoya disease in stage 3 and 4, but less effective in the evaluation of its angiographical stage.