Correlation Analysis Between Anterior Communication Aneurysms And Variation Of Willis Cycle: CTA And Clinical Study

Background and PurposeIntracranial aneurysm is the most common cause of non-traumatic subarachnoid hemorrhage(SAH), and with a high mortality rate. Early diagnosis intracranial aneurysm is associated withdecrease mortality. Computed tomographic angiography (CTA) is a useful tool for detection ofintracranial aneurysms. Variation of Willis circle is very common in intracranial aneurysmpatients. Our purpose was to assess the diagnostic accuracy of 64-slices CTA for intracranialaneurysms and the relationship between generation of anterior communication aneurysms andvariation of anterior cerebral artery and evaluate the factors related to rupture of intracranialaneurysms and the prognosis of the patients.Materials and MethodsFifty-seven patients with non-traumatic subarachnoid hemorrhage (SAH) in nonenhancedCT who also underwent 64-slices CTA were included in our study. We reviewed the CTA resultsin 57 patients and compared with digital subtraction angiography (DSA) or operation. Volumerendering (VR) and maximum intensity project (MIP) were used in CTA. Anteriorcommunication aneurysm patients which were confirmed by CTA was as an experimental group,and non-anterior communication aneurysms which cause spontaneous subarachnoid hemorrhagewas as a control group, we observed the variation of Willis circle in these two group. To evaluatethe factors associated rupture, we also observed 9 unrupture intracranial aneurysm patients, andcompared with the rupture intracranial aneurysms. The statistics is Chi-square test. The diameterof aneurysm was divided into four sizes: small, less than 5mm; medium, 5-10mm; large,10-25mm; huge, more than 25mm.ResultsFifty-seven patients in anterior communication aneurysm group (n=17) and non-anteriorcommunication group (n=40) had abnormal CTA manifestation in 57 patients. Fifty-four patientsinclude 50 intracranial aneurysms patients and 4 arteriovenous malformation patients. Only 3patients had normal CTA malformations. All the intracranial aneurysms were confirmed by DSAor operation. Fifty-night aneurysms included 19 anterior communication aneurysms (19/59,32.3%), twelve internal carotid aneurysms, eight medium cerebral aneurysms, fiveposterior cerebral aneurysms, eight anterior cerebral aneurysms, four posterior communicationaneurysms, and three vertebral aneurysms. Ten patients existed variation of Willis circle inseventeen anterior communication aneurysm group, and 7 patients in non-anteriorcommunication aneurysm group (7/40,17.5%), the difference between groups (p=0.010<0.05).Eleven intracranial aneurysms were found in nine unrupture intracranial aneurysm patients. Therupture rate doesn't have statistic difference according to the size or the location of aneurysm.ConclusionIntracranial aneurysms are the common cause of non-traumatic subarachnoid hemorrhage.Our results also show that the generation of anterior communication aneurysms is correlated withvariation of Willis circle. The rupture of intracranial aneurysms may be independent of the sizeand location of aneurysms.