Longitudinal Analysis of Location- and Growth-Associated Hemodynamics in Matched Paraclinoid Aneurysms

Predicting intracranial aneurysm growth remains difficult, with relatively few widely accepted predictors beyond aneurysm size, location, and patient age. This study investigated the relationship of vascular morphology and hemodynamics to aneurysm location and growth using a matched pairs study design that limited the influence of other predictors.

Longitudinally followed ICA aneurysms identified as growing or stable were matched by size and location, based on their proximity to either the ophthalmic arteries, superior hypophyseal arteries, or posterior communicating arteries (PComA). The 34 aneurysms (17 pairs) were monitored with 3D CTA imaging for an average of 4.10 (1.98) years. Three longitudinal image studies for each aneurysm were collected and used to reconstruct models of arterial geometry. These models were used to analyze morphology and hemodynamics over time with computational fluid dynamics simulation. Results were analyzed with the Wilcoxon signed-rank test and longitudinal multivariate models were built with generalized estimating equations clustered according to each aneurysm.

Higher average flow (P < .01) was observed at the aneurysm inlet and lower average pulsatility index at the outlet (P < .05) of aneurysms near the PComA. Over time, morphologic metrics related to size differed between paired aneurysms, but shape metrics did not. Pulsatility index at the aneurysm body and outlet differed between paired aneurysms (P < .01). Modeling identified correlates of aneurysm size including aneurysm flow and wall shear stress pulsatility index and generally demonstrated high correlation between different time points (0.94). The models showed a strong association between the attachment of the nearby artery to the aneurysm and growth.

Significant differences in hemodynamics were observed between nearby aneurysm locations. Despite the relatively small sample size, longitudinally measured hemodynamics and general aneurysm morphology were significant correlates for aneurysm growth and size, as well as possible predictors of future aneurysm growth.