Geometry Of Posterior Communicating Artery:a Possible Correlation With The Presence Of Aneurvsm

OBJECTIVE:There is a high incidence of intracranial aneurysms at the bifurcations suggesting the possibility of a geometric risk factor. So we performed this cross-sectional study to elicit the role of intracranial arterial geometry in the aneurysm formation.METHODS:This study based on87cases of patients who undergoing3D-DSA in the1st affiliate Hospital of Medical School, Zhejiang University from January2009to June2010. In these87cases, we excluded the cases those the PcomA didn’t illustrate on the3D-DSA because of the impossibility to measure the diameter of PcomA and the bifurcation angle, and finally we selected14patients who have PcomA aneurysms(cases) and those of15patients with aneurysms at other sites(AcomA or MCA e.g.)(controls), and the case were matched for age and gender with the controls. Then we performed the measurements on the Philips Integris BH5000Angiographic X-ray system, we cut the branches and measured the diameters of C6(DC6), C7(DC7) and PcomA(Dp) at5mm away from the crotch of the PcomA bifurcation, where the neck of the largest aneurysms in this study couldn’t reach. Then we measured the PcomA bifurcation angle (Ap) by placing a stent along the vessel, so that the system would display the angle of the stent, and we took this angle as the bifurcation angle. Then compare these data by using Student t test.RESULTS:First, we analyzed the diameters and the angels of the bifurction of PcomA, The mean(±SD) angles of the PcomA bifurcation were88.93°±19.63°in the14cases and113.27°±13.73°in the15controls(p<0.01). However the comparison of diameters between cases and controls showed no significant results(p>0.05). Secondly, we ranked the data by the bifurcation angle, an interesting phenomenon was seen that below84°(including84°) were all the cases and above120°(including120°) were all the controls, and the cases between84°to120°were mixed. So we choose the data range from84°to120°-16patients in all-for diameters comparison. The mean(±SD) of diameters of the PcomA was1.42±0.23mm in the7cases and1.87±0.42mm in the9controls(p<0.05), and the mean of ratio(Dp/Dc6) was0.46±0.11in the7cases and0.59±0.09in the9controls(p<0.05).CONCLUSIONS:Sharper bifurcation angles are risk factors associate with the presence of aneurysms at PcomA bifurcation. And in a certain range of angle,84±to120±in our study, larger diameter of outlet vessel would be a protective factor that prevents the presence of intracranial aneurysm at PcomA bifurcation. To determine the new indices for the clinical treatment of aneurysms, a large number of results from both parametric studies and clinical follow-up surveys are needed.