3D printing of an aortic aneurysm to facilitate decision making and device selection for endovascular aneurysm repair in complex neck anatomy.

PURPOSE: To describe rapid prototyping or 3-dimensional (3D) printing of aneurysms with complex neck anatomy to facilitate endovascular aneurysm repair (EVAR). CASE REPORT: A 75-year-old man had a 6.6-cm infrarenal aortic aneurysm that appeared on computed tomographic angiography to have a sharp neck angulation of ~90°. However, although the computed tomography (CT) data were analyzed using centerline of flow, the true neck length and relations of the ostial origins were difficult to determine. No multidisciplinary consensus could be reached as to which stent-graft to use owing to these borderline features of the neck anatomy. Based on past experience with rapid prototyping technology, a decision was taken to print a model of the aneurysm to aid in visualization of the neck anatomy. The CT data were segmented, processed, and converted into a stereolithographic format representing the lumen as a 3D volume, from which a full-sized replica was printed within 24 hours. The model demonstrated that the neck was adequate for stent-graft repair using the Aorfix device. CONCLUSION: Rapid prototyping of aortic aneurysms is feasible and can aid decision making and device delivery. Further work is required to test the value of 3D replicas in planning procedures and their impact on procedure time, radiation dose, and procedure cost.

Feasibility and limitations of an automated 2D-3D rigid image registration system for complex endovascular aortic procedures.

PURPOSE: To examine the feasibility of an automated 2-dimensional (2D) to 3- dimensional (3D) image registration system to simplify the navigational challenges faced in complex endovascular aortic procedures. METHODS: An automated 2D-3D image registration system was used to overlay pre-acquired 3D computed tomography images onto fluoroscopy images taken during endovascular aneurysm repair. Errors between the 3D overlay and digital subtraction angiograms were measured and correlated with aortic neck angulation. A mean discrepancy < or =3 mm was considered clinically acceptable. RESULTS: There was a strong correlation between maximum neck angulation and maximum registration error (Pearson's r = 0.75). Aortas with a maximum neck angulation < or =30 degrees had a mean error of 2.5+/-1.2 mm, whereas aortas with neck angulation >30 degrees had a mean error of 6.2+/-2.5 mm (p<0.0001). CONCLUSION: The major source of registration errors is aortic deformation caused by the presence of the introducer and endovascular graft. Further work is required if this technology is to be routinely applied to severely angulated aortic anatomy.