Introduction: Although 3D rotational angiography (3DRA) is routinely used for morphological and computational fluid dynamic (CFD) analysis of intracranial aneurysms, cone beam computed tomography angiography (CBCT-A), has emerged as a potentially more accurate option for angiographic imaging. The objective of this study is to determine the effect of image modality and reconstruction parameters on aneurysm analysis.
Methods: 3DRA was reconstructed using preset medium and small volume of interest (VOI) sizes, and normal and smooth kernels. CBCT-A was reconstructed over a small VOI using normal and sharp kernels. Dome size, neck diameter, and dome/neck ratio were evaluated in 3D. CFD simulations were performed on the resulting models in five aneurysms. Wall shear stress (WSS) magnitude was evaluated on the aneurysm dome, and on the area of 5% lowest WSS (LWSS).
Results: Morphological measures were higher for small vs. medium VOI, normal vs. smooth kernel, and CBCT-A vs. 3DRA modality, with up to 30% differences. Smaller VOI resulted in lower WSS for all aneurysms (1-59%). Higher resolution kernels resulted in lower WSS and LWSS (2-557%). Large WSS differences were noted between 3DRA and CBCT-A reconstructions (1-125%). In two aneurysms CBCT-A revealed aneurysms features not visible on 3DRA imaging.
Conclusions: Choice of modality and reconstruction settings has considerable effects on morphological and hemodynamic aneurysm analysis. Smaller VOI and higher resolution kernels resulted in larger morphological measurements and lower WSS. CBCT-A models had higher dome/neck sizes compared to 3DRA models, a potentially important clinical finding. Large hemodynamic differences were noted between 3DRA and CBCT-A models, particularly in regions of low WSS. Use of CBCT-A, small VOI, and high resolution kernels provided a higher level of imaging detail, possibly resulting in more accurate analysis. Mixing models across modalities and reconstruction settings could compromise the accuracy of the quantitative aneurysm evaluation.
Patient Care: This research evaluates the effect of imaging heterogeneity on aneurysm hemodynamic analysis in order to ensure hemodynamic reproducibility across modalities and reconstruction parameters. It will lead to more accurate quantitative aneurysm analysis, potentially resulting in better methodologies for clinical evaluation, rupture risk stratification, and treatment planning of intracranial aneurysms.
Learning Objectives: By the conclusion of this session participants should be able to (1) describe the effect of using different modalities and reconstruction parameters (size of volume of interest, type of kernel) on morphological and hemodynamics aneurysm analysis, and to (2) discuss the implications of mixing models across modalities and reconstruction types when performing quantitative aneurysm evaluation over large datasets.