3D Geometric Analysis of Anterior Circulation Anatomy in Patients with Intracranial Aneurysms

The formation and progression of intracranial aneurysms are influenced by multiple factors. Previous studies have shown the local geometry surrounding an aneurysm to influence its development. The geometry of the global cerebral vasculature, however, and its potential effects on aneurysms have not been well elucidated. We hypothesized that select geometries within the anterior cerebral circulation would differ among those with ruptured and unruptured aneurysms.

We conducted a retrospective analysis of 38 patients who presented to our institution for catheter-based 3D rotational cerebral angiography for assessment of intracranial aneurysms. Geometric analysis was conducted using Materialise Mimics and 3-Matic.

Those with a ruptured aneurysm (n = 7) had a significantly larger bifurcation angle between the anterior cerebral artery (ACA) and middle cerebral artery (MCA) compared to patients with unruptured aneurysms (97.96°, 91.60°, P = 0.01). Subgroup analysis demonstrated larger ACA diameters in the cohort of patients with ACA aneurysms (3.14 mm) compared to those with internal carotid artery (ICA) and MCA aneurysms (2.45 mm, 2.61 mm, P = 0.004). Patients over the age of 65 had larger MCA bifurcation angles (94.87°) compared to their younger counterparts (86.58°, P = 0.024). Males exhibited a significantly larger petrous ICA diameter (5.33 mm vs. 4.53 mm, P < 0.001), ICA genu diameter (4.97 mm vs. 4.43 mm, P = 0.017), and ACA diameter (2.96 mm vs. 2.55 mm, P = 0.010), compared to female patients, but a smaller ACA-MCA bifurcation angle (91.11° vs. 94.31°, P = 0.039).

We conclude that geometric differences may be the result of systemic vascular remodeling and a potential indicator of aneurysm integrity.