Reproducibility of image-based computational models of intracranial aneurysm: a comparison between 3D rotational angiography, CT angiography and MR angiography

Abstract

Background: Reconstruction of patient-specific biomechanical model of intracranial aneurysm has been based on different imaging modalities. However, different imaging techniques may influence the model geometry and the computational fluid dynamics (CFD) simulation. The aim of this study is to evaluate the differences of the morphological and hemodynamic parameters in the computational models reconstructed from computed tomography angiography (CTA), magnetic resonance angiography (MRA) and 3D rotational angiography (3DRA).

Methods: Ten patients with cerebral aneurysms were enrolled in the study. MRA, CTA and 3DRA were performed on all patients. For each patient, three patient-specific models were reconstructed respectively based on the three sets of imaging data of the patient. CFD simulations were performed on each model. Model geometry and hemodynamic parameters were compared between the three models.

Results: In terms of morphological parameters, by comparing CTA based models (CM) and 3DRA based models (DM) which were treated as the "standard models", the aspect ratio had the minimum difference (Δ = 8.3 ± 1.72 %, P = 0.953) and the surface distance was 0.25 ± 0.07 mm. Meanwhile, by comparing MRA based models (MM) and DM, the size had the minimum difference (Δ = 6.6 ± 1.85 %, P = 0.683) and the surface distance was 0.36 ± 0.1 mm. In respect of hemodynamic parameters, all three models showed a similar distribution: low average WSS at the sack, high OSI at the body and high average WSSG at the neck. However, there was a large variation in the average WSS (Δ = 34 ± 5.13 % for CM, Δ = 40.6 ± 9.21 % for MM).

Conclusion: CTA and MRA have no significant differences in reproducing intracranial aneurysm geometry. The CFD results suggests there might be some significant differences in hemodynamic parameters between the three imaging-based models and this needs to be considered when interpreting the CFD results of different imaging-based models. If we only need to study the main flow patterns, three types of image-based model might be all suitable for patient-specific computational modeling studies.

Keywords: Aneurysm; Angiography; CFD; CTA; DSA; MRA; Reproducibility.

Fig. 1

Model reconstruction of patient-specific model. a A original image data, b a rough model by using the threshold segmentation and artificially adjusting, c the final model after surface smoothing, d showing different areas in the model. Arrows represent the aneurysm

Fig. 2

The illustration of the morphological parameters. a Definition of size and AR, b definition of AA and SR

Fig. 3

Differences distribution for morphologic parameters. a Difference between CM and MM, b difference between MM and DM

Fig. 4

Surface distance distribution of a cerebral aneurysm located in ICA

Fig. 5

Surface distance data (mean and standard deviation) of the patients

Fig. 6

The distribution of AWSS, OSI and AWSSG in the three image based models (DM, CM and MM)

Fig. 7

Differences distribution for hemodynamic parameters. a Difference between CM and DM, b difference between MM and DM

Fig. 8

Velocity-colored streamline at the peak systole of two aneurysms located on ACA-A1 (top row) and ACoA (bottom row). Models based on different imaging techniques were present from left to right (DM, CM and MM).The black arrow shows the flow direction