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SPECT and MRI evaluations of the posterior circulation in moyamoya disease
Unlabelled:
We evaluated the posterior circulation in patients with moyamoya disease by SPECT and MRI.
Methods:
Six patients with idiopathic moyamoya disease were studied by SPECT, MRI and angiography. Patients received an injection of 555-740 MBq of 99mTc-HMPAO, after which SPECT images were taken. The cerebral-to-cerebellar activity ratio in five cerebral regions was calculated to assess the regional cerebral blood flow (rCBF). The SPECT and MRI findings were then compared with angiographic.
Results:
Of the 12 posterior cerebral arteries (PCAs) in the six patients studied, seven PCAs (58%) in five patients had a stenotic or occluded lesion. Furthermore, rCBF in all five regions significantly decreased as the degree of steno-occlusive lesions of the PCA progressed. No significant correlation, however, was found between the steno-occlusive lesions of the internal carotid artery bifurcation and the rCBF. The rCBF significantly decreased in the absence of leptomeningeal collateral vessels from the PCA to the anterior circulation. On the basis of the MR images, the frequency of cerebral infractions significantly increased in patients with steno-occulasive PCA lesions.
Conclusion:
The rCBF in moyamoya disease decreases proportionally with the degree of steno-occlusive lesions of the PCA. The steno-occlusive PCA lesions decrease the number of leptomeningeal collateral vessels to the anterior circulation, thereby causing severe cerebral ischemia that is likely to result in infractions.