Abstract
In order to evaluate the relationship between CT and angiographic findings, especially the degree of collateral circulation estimated by 4-vessel study, 47 cases with internal carotid artery occlusion were studied by CT and angiography. The CT findings showed large infarction in 16 cases and small infarction in 24, but 7 cases had no infarction. The CT findings were classified into 7 types : combined superficial + deep type; watershed type; hemispheric type; deep type; atrophic type; and superficial type were present in 12, 10, 8, 6, 5, and 4 cases, respectively. The angiography demonstrated contralateral internal carotid stenosis in 5 cases, contralateral A1-hypoplasia in 3 cases, and occlusio-supra-occlusionem in 6 cases, in addition to internal carotid artery occlusion (5 cases with bilateral internal carotid artery occlusion). Markedly apparent collaterals were seen; ophthalmic anastomoses (Oph.) in 30%, via the circle of Willis (CW) in 53%, and leptomeningeal anastomoses (LM) in 30%. In CW, cross-filling was seen, mainly through the anterior communicating artery in the anterior cerebral artery (ACA) and middle cerebral artery (MCA) region. LM was seen mainly as back-flow from posterior cerebral artery to ACA/MCA region. Among the various combinations of collaterals, 46% were Oph (-) + CW (_??_), + LM (-+). The size of the infarcted area generally depended on CW. But since 28% of CW (_??_) presented large infarctions of the MCA region it is likely that either an occlusio-supra-occlusionem or a propagation of secondary thrombosis from occluded site temporarily blocked the cross-filling through CW. On the other hand, in CW (-+) the combination of Oph and LM determined the size of the infarcted area. But large infarctions were seen in 36% of the Oph (+) /LM (_??_) combination, suggesting that the speed of occlusion of the internal carotid artery influenced the formation of an infarction. That is, the rapid occlusion made the infarcted area larger due to arteriolo-arteriolo anastomoses of Oph and LM.
In this study it seems difficult to conclusively make a clear correlation between the CT and angiographic findings. However, considering the pathophysiological condition, we can say that a good correlation of angiographic assessment of collateral circulation with the CT findings was present.
