Comparative performance of magnetic resonance angiography and conventional angiography in moyamoya disease

Patients with moyamoya disease verified by conventional cerebral angiography (CCA) were evaluated by means of magnetic resonance angiography (MRA), in order to clarify its advantages and limitations in comparison with CCA. This retrospective study was carried out in 13 hemispheres of seven patients with moyamoya disease (including one atypical patient). In MRA, magnetisation transfer contrast (MTC) and maximal intensity projection (MIP) techniques were used. A good correspondence between MRA and CCA was noted in 11 hemispheres (86.4%) on evaluating stenotic lesions and overestimation in the remaining 2. Underestimation of moyamoya vessels in MRA was noted in 3 hemispheres, since well developed moyamoya vessels were detectable, while poorly developed ones were not. No difference between MRA and CCA findings was found in 10 hemispheres (76.9%). MRA tends to overestimate the stenosis and underestimate moyamoya vessels. These characteristics may lead to wrong classification in the angiographic grade of patients with early and advanced stages and should be taken into consideration in interpreting MRA images of moyamoya disease (compatible rate of grade between MRA and CCA; 84.6%). In conclusion MRA with MTC and MIP techniques offers an acceptable quality of assessment of stenotic lesions and moyamoya vessels. MRA is a useful follow up method at present and in the near future it may replace CCA as the initial diagnostic tool.