Article Text
PDF
Abstract
Introduction Aneurysm morphology is a determinant factor that influences risk of rupture. Aneurysmal wall enhancement (AWE) has also been associated with increased risk of rupture. Emerging tools including finite element analysis (FEA) and computational fluid dynamics (CFD) may provide insights about aneurysm dynamics. We analyzed AWE, CFD, and FEA to identify the interaction between various metrics in aneurysm morphology.
Methods Only unruptured saccular aneurysms were included. 3T MRI was used to image aneurysms. Two sequences were performed: T1 and T1 after administering gadolinium (Gd). 3D segmentations were produced using 3D slicer. Signal intensity heat maps were generated to quantify AWE. AWE uptake was calculated as the difference between T1+Gd and T1 signal intensity. Wall tension (WT) was calculated using FEA. The time averaged wall shear stress (TAWSS) and the wall sheer stress gradient (WSSG) were calculated with CFD. Finally, aneurysm size, aspect ratio (AR), and size ratio (SR) were calculated in the best image projection. Aneurysms with multiple lobes and/or daughter sacs were considered irregular.
Results Forty-seven aneurysms were included in the study. The median aneurysm size was 6.3 (IQR=4.9, 8.2) mm, the median AR was 1.53 (IQR=1.06, 1.98), and the median SR was 2.61 (IQR=1.54, 3.90). Eighteen aneurysms (38%) were irregular and 29 (62%) had regular morphology. Irregular aneurysms had a significantly higher median WT compared to regular aneurysms (p=0.05). Additionally, irregular aneurysms had a lower median TAWSS (p=0.04) and WSSG (p=0.04) compared to regular aneurysms. WT was also higher in aneurysms larger than 6.1 mm (p<0.001), aneurysms with an AR over 1.5 (p<0.001), and aneurysms with a SR over 2.3 (p<0.001). Similar to irregular aneurysms, highly enhancing aneurysms had higher WT compared to non-enhancing aneurysms (p=0.02). Aneurysms in the ACOM and PCOM had the lowest TAWSS and WSSG (figure 1).
Conclusion Irregular aneurysms tend to have a high WT and low TAWSS and WSSG. Aneurysms with high AWE also have high WT. High-risk locations such as the ACOM have the lowest TAWSS and WSSG. A comprehensive analysis may aid in identifying high-risk aneurysms with a higher accuracy.
This figure shows the highest 25% of AWE in an ACOM aneurysm (A). In this specific location, there is high WT (B) and low TAWSS (C) and WSSG (D)
Disclosures J. Miller: None. S. Sanchez: None. A. Galloy: None. M. Nino: None. D. Ojeda: None. L. Noboa: None. D. Hasan: None. E. Samaniego: None.