Localized hemodynamic assessment and rupture risk evaluation of intracranial aneurysms using the TESLA framework via...

Intracranial aneurysms, particularly saccular types, are localized dilations of cerebral vessels prone to rupture, leading to life-threatening complications such as subarachnoid hemorrhage.

This study aimed to characterize the localized hemodynamic environment within the aneurysm dome and evaluate how spatial interactions among key flow parameters contribute to rupture risk, using a synergistic analytical framework.

We applied the targeted evaluation of synergistic links in aneurysms (TESLA) framework to analyze 18 intracranial aneurysms from 15 patients. Patient-specific vascular geometries were reconstructed from high-resolution three-dimensional (3D) time-of-flight magnetic resonance angiography (TOF-MRA), acquired using a 1.5T magnetic resonance imaging (MRI) scanner (MAGNETOM Aera, Siemens Healthineers) with a 20-channel head and neck coil. TOF-MRA employed a gradient-echo sequence leveraging the inflow effect to enhance signal intensity from flowing blood, obviating the need for contrast agents. Imaging parameters were: TR/TE = 24/7 ms, flip angle = 22°, field of view (FOV) = 230 × 200 mm², matrix size = 320 × 196, 100 contiguous slices with a slice thickness of 0.7 mm, and voxel dimensions = 0.72 × 1.02 × 0.7 mm³ (acquired) and 0.7 × 0.7 × 0.7 mm³ (reconstructed isotropic). Computational fluid dynamics (CFD) simulations were performed to wall shear stress (WSS), time-averaged WSS (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), pressure gradient (PG), and vorticity. A standardized pulsatile inflow waveform (mean flow rate: 275 mL min^-1) was applied uniformly at the inlet of each model. Outflow boundary conditions assumed constant pressure at distal locations, with resistance equalization via extension segments. Hemodynamic parameters were compared between ruptured and unruptured aneurysms.

The CFD analysis of 18 intracranial aneurysms revealed marked hemodynamic heterogeneity within the aneurysm dome, with WSS ranging from an average of 0.7042 Pa in low-stress zones associated with stagnant flow to peaks of 54.0371 Pa in high-stress regions indicative of mechanical strain, while TAWSS averaged 12.4875 Pa with maximum values reaching 25.9159 Pa, highlighting localized stress amplifications. Vorticity averaged 2,422.34 s^-1 with peaks up to 4,645.50 s^-1, reflecting turbulent and recirculating flow, complemented by an OSI averaging 0.4557 and peaking at 0.4952, and RRT averaging 6.2278 Pa^-1, both signifying oscillatory flow and stagnation linked to increased wall vulnerability. Comparative analysis between ruptured and unruptured aneurysms demonstrated markedly higher maximum values of WSS, TAWSS, OSI, PGs, and vorticity (averaging 33,635.322 Pa m^-1 and peaking at 47,390.5 Pa m^-1) in ruptured cases, alongside elevated RRT, underscoring the association of extreme hemodynamic disturbances with rupture risk.

The TESLA framework effectively captured localized hemodynamic extremes-elevated stress, oscillatory flow, and prolonged residence time-that were more pronounced in ruptured aneurysms. These findings support TESLA's utility in improving rupture risk assessment and guiding personalized clinical management.