Segmenting outer heart walls & septum for developing heart mold

Dear all

For my Master Thesis I need an ± anatomically correct, physical heart phantom and for this I should produce a heart mold. I intended to make a heart mold based on ideas described in the work of Tibamoso-Pedraza et al. (see citation below) using the CTACardio data in 3D Slicer. In the work of Tibamoso-Pedraza et al., they first segment a solid body of the whole heart in Slicer, and from this region, they extract boundaries of a certain thickness to create a hollow heart shape. Afterwards, the septum’s region is segmented to create the ventricular and atrial cavities. The negative of this segmented heart shape is used to create the final heart mold. However, it is not clear to me how to approach the boundary extraction in 3D Slicer. I would be very grateful for any help or comment that can bring me closer to my goal. I hope I have expressed my question clearly enough. Thank you in advance!

Kind regards Marthe

Tibamoso-Pedraza, G., Navarro, I., Dion, P., Raboisson, M., Lapierre, C., Miró, J., Ratté, S., & Duong, L. (2021). Design of heart phantoms for ultrasound imaging of ventricular septal defects. International Journal of Computer Assisted Radiology and Surgery , 17 (1), 177–184. Design of heart phantoms for ultrasound imaging of ventricular septal defects | International Journal of Computer Assisted Radiology and Surgery