Challenges and limitations of patient-specific vascular phantom fabrication using 3D Polyjet printing

Abstract

Additive manufacturing (3D printing) technology offers a great opportunity towards development of patient-specific vascular anatomic models, for medical device testing and physiological condition evaluation. However, the development process is not yet well established and there are various limitations depending on the printing materials, the technology and the printer resolution. Patient-specific neuro-vascular anatomy was acquired from computed tomography angiography and rotational digital subtraction angiography (DSA). The volumes were imported into a Vitrea 3D workstation (Vital Images Inc.) and the vascular lumen of various vessels and pathologies were segmented using a “marching cubes” algorithm. The results were exported as Stereo Lithographic (STL) files and were further processed by smoothing, trimming, and wall extrusion (to add a custom wall to the model). The models were printed using a Polyjet printer, Eden 260V (Objet-Stratasys). To verify the phantom geometry accuracy, the phantom was reimaged using rotational DSA, and the new data was compared with the initial patient data. The most challenging part of the phantom manufacturing was removal of support material. This aspect could be a serious hurdle in building very tortuous phantoms or small vessels. The accuracy of the printed models was very good: distance analysis showed average differences of 120 μm between the patient and the phantom reconstructed volume dimensions. Most errors were due to residual support material left in the lumen of the phantom. Despite the post-printing challenges experienced during the support cleaning, this technology could be a tremendous benefit to medical research such as in device development and testing.

Comparison of Modern Stroke Thrombectomy Approaches Using an In Vitro Cerebrovascular Occlusion Model

“…8,9 This model closely resembles the human intracranial circulation and consists of 3 separate inflow channels mimicking the basilar artery and the 2 intracranial ICA branches. The design includes the MCA branches (M1-M4 segments with the smallest vessels of 1 mm in diameter), bilateral A1 anterior cerebral artery segments connected to a single anterior cerebral artery, and a single posterior communicating artery (right side), allowing near-complete circle of Willis circulation.…”

“…A novel in vitro intracranial cerebrovascular occlusion model for testing thrombectomy devices was developed recently. 8,9 This 3D printed model is uniquely constructed on the basis of patientspecific anatomies to mimic a typical intracranial circulation by the presence of robust collaterals through both anterior and posterior communicating arteries and the typical tortuosity encountered in the intracranial circulation. In addition, the modulus of the model is closer to normal physiologic vessels than typical silicone models, allowing a feel and device deformation that are similar to those in a real clinical situation.…”

Selective Mineralization of Tough Hydrogel Lumens for Simulating Arterial Plaque

“…[10][11][12][13][14][15][16] Most prior designs have been composed of inorganic materials such as glass, [10,11] which do not match the material properties of soft tissues in real human arteries. Silicone-based elastomeric materials have also been widely used, [12,13] such as Elastrat Sarl (Switzerland), [12] to construct phantom models; however, the phantoms were usually mono-layered and single material, and therefore, did not reproduce the wall architecture or chemistry present in plaque.…”

“…Silicone-based elastomeric materials have also been widely used, [12,13] such as Elastrat Sarl (Switzerland), [12] to construct phantom models; however, the phantoms were usually mono-layered and single material, and therefore, did not reproduce the wall architecture or chemistry present in plaque. Other attempts have also been made to directly print vascular phantoms by 3D Polyjet printers, using either hard (acrylic) or elastomeric materials (polyurethane), [14] or by hydrogel molding, using polyvinyl alcohol (PVA). [16] In several cases, stenotic geometries were evaluated showing that these features will influence flow and deformational mechanics of the arterial wall.…”

Three-dimensional printing technology for treatment of intracranial aneurysm

“…Such a model would also inspire neurosurgeons to get new scientific research ideas in the areas of surgical techniques and the shape of aneurysms. [21] Furthermore, training and assessment of surgical skills through the physical models will advance competency training.…”