자기공명 혈관조영 소견을 이용한 윌리스 환 후부위의 형태학적 변이 조사

Abstract

Background: The arterial circle of Willis at the base of the brain serves as a potential collateral pathway, whichenables to maintain adequate cerebral perfusion in case of diminished afferent blood supply through the internalcarotid artery (ICA) or the basilar artery. While its function depends on the continuity of its circular configuration,it is known to vary. The anatomic variants of circle of Willis have been studied based on conventional angiograph-ic or autopsy studies. With the advent of magnetic resonance angiography (MRA), the anatomic variation of theposterior part of circle of Willis can be easily demonstrated in a physiologic state.

Methods: Among the subjectswho underwent both brain magnetic resonance imaging and MRA in the Yonsei Medical Center from 2000 to2003, those without a brain parenchymal lesion and without abnormalities of intracranial and neck vessels wereincluded in the present study. The anatomic variants of the posterior part of the circle were determined by the pres-ence of the posterior communicating artery (PcomA) or the precommunicating segment of the posterior cerebralartery (PCA). The variants were categorized into six groups: type A, bilateral PcomA; type B, unilateral PcomAand fetal type PCA; type C, unilateral PcomA; type D, unilateral fetal type PCA; type E, bilateral fetal type PCA;and type F, no continuity between the ICA and PCA.

Results: Of 1884 subjects, 324 who met the inclusion crite-ria, were finally included for analyses. They were 152 males and 172 females, and the mean age was 54.2 years(range, 3/12~87 years). Type F was most common (171 subjects, 54.8 %), followed by type C (51, 15.6 %), typeD (40, 12.4 %), type A (22, 6.8 %), type B (22, 6.8 %), and type E (5.6 %). In summary, while about a half of thesubjects had no continuity between anterior and posterior circulations, the PCA was supplied only from the anteri-or circulation through the fetal-type PCA in a significant portion of subjects.

Conclusion: We investigated normalreference values for morphologic variants of the posterior part of the circle of Willis based on MRA in Korean.These results would be helpful for consideration of the mechanism and pathogenesis in stroke patients.