gms | German Medical Science

Objective: Complete tumor resection is essential for treatment of skull base chondrosarcomas. Mostly located at the petrous apex, anatomical complexity and rarity of the disease make surgery a challenging task. 3D printed models could simplify preoperative planning because they would allow simulation of surgery. However, common single color 3D-printing techniques only depict the surface, while structures beneath cannot be differentiated. Conversely, color jet printing technology produces volumetrically colored 3D prints suitable for simulation of even interlocking structures such as tumor wrapping around vessels. This case study was performed to evaluate fully colored 3D-prints (Figure 1A [Fig. 1]) of patients with intracranial chondrosarcomas regarding accurate reproduction and suitability for preoperative planning and surgical simulation.

Methods: CT, CTA and MRI data of the patients were spatially fused on each other followed by manual segmentation and coloring of relevant structures such as bone, vessels, tumor, optic nerve and pituitary gland in a 3D printing software. The models were printed with color jet printing technology (ZPrinter 450, 3DSystems, Rock Hill, S.C., USA). With this technique plaster based powder is solidified and colored by partially applying binder and the respective ink onto every layer during production. After printing a polymer solution was applied to increase stability.

Results: Printed models were CT scanned and compared to the initial 3D data. In 50 randomly chosen points the deviation between the two models showed a mean distance of 0,021 mm (SD+/-0.076 mm) depicting a high overlapping accuracy (Figure 1B [Fig. 1]). Temporal craniotomy and removal of the tumors using a high speed drill were successfully performed. Unlike other plastic materials often used by filament printers the plaster material showed excellent behavior while drilling and cutting. No melting or deformation occurred. Depending on the printer’s settings the whole volume of a model can be colored. This allows e.g. for successively removing tumor and revealing a red colored blood vessel inside (Figure 2A and B [Fig. 2]).

Conclusion: In this case study fully colored 3D prints were produced resulting in visual appealing and tangible models, which matched the individual patients’ anatomy with high accuracy. Coloring objects inside a volume allows for simulation of even complex configurations (vessel inside of tumor). Major drawbacks were seen in the fact of missing soft tissue to simulate e.g. brain retraction.