Comprehensive morphomechanical and wall enhancement analysis of intracranial aneurysms

Understanding the relationship between aneurysm wall enhancement (AWE), wall shear stress (WSS), and wall tension (WT) across different brain aneurysm compartments may improve the assessment of rupture risk and vessel wall dynamics. Our comprehensive analysis aimed to evaluate these characteristics across different brain aneurysm compartments.

Patients with intracranial aneurysms underwent 3-T high-resolution magnetic resonance imaging (MRI). T1-weighted images were obtained before and after administering gadolinium (Gd) contrast. 3D segmentations of the aneurysms were generated using 3D Slicer. AWE was quantified based on the signal intensity of the aneurysm wall on T1+Gd images. Finite element analysis calculated WT, while computational fluid dynamics assessed WSS metrics, including time-averaged wall shear stress (TAWSS), wall shear stress gradient (WSSG), and oscillatory shear index (OSI). AWE, WT, and WSS metrics were compared among aneurysms compartments and aneurysms stratified by size, aspect ratio (AR), and size ratio (SR).

AWE was elevated in aneurysms with greater size and AR. WT and OSI were higher in aneurysms with larger sizes and higher AR and SR. Aneurysm necks exhibited higher WT, TAWSS, and WSSG compared to the aneurysm body. Irregular aneurysms displayed lower TAWSS, WSSG, and higher OSI in areas of high AWE. The bleb had the highest AWE and lowest WT and WSSG, while necks showed the lowest AWE and highest WT and WSSG.

Aneurysm necks typically exhibit high WT and WSS, while the body often shows low WSS. Blebs express elevated AWE alongside diminished WSS and WT which potentially increases rupture risk KEY POINTS: Question Areas of high wall enhancement in irregular aneurysms are characterized by low wall sheer stress and high oscillatory sheer index. Findings High risk structures such as daughter sacs exhibit the highest wall enhancement and lowest wall sheer stress. Clinical relevance Comprehensive morphomechanical and wall enhancement analysis of brain aneurysms have the potential to offer valuable new insights into aneurysm biology.