Vascular Flow Phantom of A Cohort-Based Averaged Abdominal Aortic Aneurysm: Design, Fabrication and Characterization

Vascular flow phantoms are an invaluable tool for in vitro and in silico studies, but their design and fabrication processes are often not reported. In this study, a framework is introduced to design and fabricate 3D printable high-fidelity cohort-based averaged abdominal aortic aneurysm (AAA) phantoms.

AAA geometries of 50 patients were segmented from preoperative computed tomography angiography scans. The segmented geometries and center lumen lines (CLL) were used in an in-house developed algorithm to average the CLL coordinates and corresponding diameters over the entire cohort. The reconstructed averaged anatomy was 3D printed as a thin-walled flow phantom with Formlabs Flexible 80A resin. The acoustic properties of the resin were characterized and the feasibility of flow field quantification inside the phantom with ultrasound particle imaging velocimetry (echoPIV) was investigated.

Comparison between patient-specific models generated by our method and their corresponding reference segmentations, for ten patients, showed a mean Sørensen-Dice similarity coefficient of 0.916 ± 0.21 and the largest distances (5-10% of the lumen diameter) were found at the aneurysmal sac. The Flexible 80A resin had an average speed of sound of 1785 m/s, attenuation of 7.8 dB/mm and density of 1130 kg/m³. Volumetric flow profiles obtained with echoPIV in the suprarenal artery (i.e. phantom inlet) matched the flow sensor data.

The reported framework was used to make an averaged, cohort-based AAA model, which showed a good match with its reference model. A 3D printed, thin-walled phantom was made based on this model and the feasibility of flow field quantification inside the phantom was shown.