Manufacturing flexible vascular models for cardiovascular surgery planning and endovascular procedure simulations: An approach to segmentation and post-processing with open-source software and end-user 3D printers

Abstract

306Three-dimensional (3D)-printed vascular models for cardiovascular surgery planning and endovascular procedure simulations often lack realistic biological tissues mimicking material properties, including flexibility or transparency, or both. Transparent silicone or silicone-like vascular models were not available for end-user 3D printers and had to be fabricated using complex and cost-intensive workarounds. This limitation has now been overcome by novel liquid resins with biological tissue properties. These new materials enable simple and low-cost fabrication of transparent and flexible vascular models using end-user stereolithography 3D printers and are promising technological advances toward more realistic patient-specific, radiation-free procedure simulations and planning in cardiovascular surgery and interventional radiology. This paper presents our patient-specific manufacturing process of fabricating transparent and flexible vascular models using freely available open-source software for segmentation and 3D post-processing, aiming to facilitate the integration of 3D printing into clinical care.

Keywords: 3D printing; Biological tissue; Endovascular simulation; Flexible; Resin.

Figure 1

309 Process of ROI interpolation in segmenting vascular structures. Based on a DICOM stack of CTA images in arterial contrast phase, the regions of interest were interpolated from manually defined regions (yellow dotted lines). Using a macro, the structures outside these regions were removed, resulting in an image stack of the visceral arteries.

Figure 2

Results of segmentation and 3D post-processing. (A) Segmentation after removing all non-vascular structures and smoothing. (B) Surface model generated by stack triangulation using the integrated 3D Viewer plugin. (C) Vascular model after using the “Bisect” tool to remove unnecessary arteries and cut the vessels open in Blender. (D) Vascular model after generating vascular walls with 1-mm wall thickness (white arrow heads).

Figure 3

Thoracic aortic aneurysm in right descending aorta with Kommerell’s diverticulum. (A) Coronal projection of the CTA. (B) Parasagittal maximum intensity projection of the thoracic aorta. (C) 3D reconstruction of the thoracic aorta, representing the right descending course. (D) 3D-printed model of the thoracic aorta. (E) Proof of flexibility of the silicone-like resin. Abbreviations: Asc, ascending aorta; KD, Kommerell’s diverticulum; TAA, thoracic aortic aneurysm.

Figure 4

Segmental renal artery bleeding after percutaneous nephrostomy. (A) Coronal projection of the preprocedural CT scan in arterial phase (white arrow: nephrostomy catheter; white arrow heads: affected segmental renal artery). (B) Flexible resin vascular model (black arrow heads: segmental artery; single star: right renal artery; double star: proper hepatic artery). Abbreviation: Ao, infrarenal aorta.

Figure 5

Splenic pseudoaneurysm with arterial hemorrhage from pancreatitis. (A) Axial projection of the preprocedural CT scan with pseudoaneurysm of the splenic artery (white arrow head). (B) 3D-printed vascular model of the visceral arteries, including the pseudoaneurysm (black arrow head). (C) Simulation setting of the 3D-printed model connected to a peristaltic water pump while performing microcatheter navigation in the splenic artery. Abbreviations: Ao, aorta; Gb, gall bladder; Ki, kidney; Li, Liver; Pa, pancreas; Pc, pseudocyst; Sp, spleen; *, celiac trunk; **, superior mesenteric artery