A New Method of Intracranial Aneurysm Modeling for Stereolithography Apparatus 3D Printer: The "Wall-Carving Technique" Using Digital Imaging and Communications in Medicine Data

Objective: To assess the ability of the "wall-carving (WC) image technique", which uses vascular images from 3-dimensional digital subtraction angiograms (3DDSAs). Also, to verify the accuracy of the resulting 3D-printed hollow models of intracranial aneurysms.

Methods: The 3DDSA data from 9 aneurysms were processed to obtain volumetric models suitable for the stereolithography apparatus. The resulting models were filled with iodinated contrast media. 3D rotational angiography of the models was carried out, and the aneurysm geometry was compared with the original patient data. The accuracy of the 3D-printed hollow models' sizes and shapes was evaluated using the nonparametric Wilcoxon signed-rank test and the Dice coefficient index.

Results: The aneurysm volumes ranged from 34.1 to 4609.8 mm³ (maximum diameters 5.1-30.1 mm), and no statistically significant differences were noted between the patient data and the 3D-printed models (P = 0.4). Shape analysis of the aneurysms and related arteries indicated a high level of accuracy (Dice coefficient index value: 88.7%-97.3%; mean ± SD: 93.6% ± 2.5%). The vessel wall thickness of the 3D-printed hollow models was 0.4 mm for the parent and 0.2 mm for small branches and aneurysms, almost the same as the patient data.

Conclusions: The WC technique, which involves volume rendering of 3DDSAs, can provide a detailed description of the contrast enhancement of intracranial vessels and aneurysms at arbitrary depths. These models can provide precise anatomic information and be used for simulations of endovascular treatment.