Patient specific biomodel of the whole aorta - the importance of calcified plaque removal

Background: The use of anatomical models produced by 3D printing technique (rapid prototyping, RP) is gaining increased acceptance as a complementary tool for planning complex surgical interventions. This paper describes a method for creating a patient specific replica of the whole aorta. Methods: Computed tomography angiography (CTA) DICOM-data was converted to a three-dimensional computer aided design-model (CAD) of the inner wall of the aorta representing the lumen where the calcified plaque contribution was removed in a multi-step editing-manoeuvre. The edited CAD-model was used for creating a physical plaster model of the true lumen in a 3D-printer. Elastic and transparent silicon was applied onto the plaster model, which was then removed leaving a silicon replica of the aorta. Results: The median (interquartile range) difference between diameters obtained from CTA- and RP plaster-model at 19 predefined locations was 0.5 mm (1 mm) which corresponds to a relative median difference of 4.6% (7.0%). The average wall thickness of the silicone model was 3.5 mm. The elasticity property and performance during intervention was good with an acceptable transparency. Conclusions: The integration of RP-techniques with CAD based reconstruction of 3D-medical imaging data provides the needed tools for making a truly patient specific replica of the whole aorta with high accuracy. Plaque removal postprocessing is necessary to obtain a true inner wall configuration.