Geometric Parameter Analysis of Ruptured and Unruptured Aneurysms in Patients with Symmetric Bilateral Intracranial Aneurysms: A Multicenter CT Angiography Study

Abstract

BACKGROUND AND PURPOSE:Previous studies of geometric and morphologic parameters of intracranial aneurysms have been conducted to determine rupture risk, which remains incompletely defined due to patient-specific risk factors, such as sex, hypertension, and age. To this end, we compared characteristics of ruptured and unruptured aneurysms in the same patients with symmetric bilateral intracranial aneurysms.

Morphological and numerical assessment of intracranial aneurysms ruptures risk

“…This form of aneurysm was described by Weir in 1987 [28]. In recent years, more and more researchers [4,8,11,16,22,23] point to the fact that ruptured aneurysms have irregular shape. From the mechanical point of view, wall of an aneurysm with inhomogeneities can have an inhomogeneous stress field, and structure of the flow inside such aneurysms becomes unstable and inhomogeneous.…”

“…Moreover, it was noted that irregular shape of aneurysm dome indicates a high risk of rupture, regardless of its size [11,22]. The appearance of irregularities on the surface of aneurysm dome indicates degradation of its wall and a possible thrombosis of its lumen [22].…”

“…Moreover, ruptured aneurysms, in contrast to unruptured ones, had more complex structure of blood flow and multiple vortices. This can be explained by the fact that as a rule ruptured aneurysms have inhomogeneous structure of the wall, which assumes the presence of aneurysms in aneurysm (so-called irregular shape) [8,11,22].…”

“…The study was carried out using methods of computational fluid dynamics (CFD), which makes it possible to evaluate blood flow in aneurysms. [29] 2003 Size of aneurysm 7 mm and more -for ruptured [8] 2008 Size ratio 2.05 and more -for ruptured [23] 2010 Size ratio 2.57 -average for unruptured 4.08 -average for ruptured more than 3 -for ruptured [21] 2014 Size of aneurysm, irregular shape 9 mm and more -for ruptured [5] 2015 Size ratio 1.55 -average for unruptured 2.09 -average for ruptured [11] [20] 2017 Size of aneurysm 7 mm and more -for ruptured [10] 2017 Size of aneurysm between 5 and 10 mm -size of ruptured [25] 2017 Size of aneurysm Not availible [3] 2017 Size of aneurysm, irregular shape 2.5 mm -average for unruptured 6.9 mm -average for ruptured [9] 2017 Size ratio 2.1 and more -for ruptured [4] 2018 Size ratio Not availible [24] 2016 Size ratio, size of aneurysm Size ratio more than 1.5 -for ruptured [2] 2013 Size of aneurysm Aneurysms of the anterior communicating artery with 4 mm in diameter should be treated. Other aneurysms less than 7 mm in size have a small risk of rupture.…”

“…Among such factors, first of all, researchers consider size of aneurysms [6]. Authors also estimate size ratio of aneurysm [1,2,9,10], aspect ratio, as well as irregular shape [4,11], wall shear stress [2], effective stresses in the wall, blood pressure in aneurysm dome [12].…”