Additive Fabrication of a Vascular 3D Phantom for Stereotactic Radiosurgery of Arteriovenous Malformations

Abstract

In this study, an efficient methodology for manufacturing a realistic three-dimensional (3D) cerebrovascular phantom resembling a brain arteriovenous malformation (AVM) for applications in stereotactic radiosurgery is presented. The AVM vascular structure was 3D reconstructed from brain computed tomography (CT) data acquired from a patient. For the phantom fabrication, stereolithography was used to produce the AVM model and combined with silicone casting to mimic the brain parenchyma surrounding the vascular structure. This model was made with tissues-equivalent materials for radiology. The hollow vascular system of the phantom was filled with a contrast agent usually employed on patients for CT scans. The radiological response of the phantom was tested and compared with the one of the clinical case. The constructed model demonstrated to be a very accurate physical representation of the AVM and its vasculature and good morphological consistency was observed between the model and the patient-specific source anatomy. These results suggest that the proposed method has potential to be used to fabricate patient-specific phantoms for neurovascular radiosurgery applications and medical research.

Keywords: additive manufacturing; anthropomorphic phantoms; stereolithography; surgical applications; tissue-equivalent materials.

FIG. 1.

Workflow adopted for the vascular phantom realization. (A) Schematic illustration of the DECT scanner employed for CT imaging and a representative image acquired. The green circle highlights the presence of the AVM. (B) 3D rendering elaborated from CT images, used to identify and isolate the AVM (green circle) from the surrounding anatomical structures. (C) 3D solid model of the AVM and (D) 3D model elaboration using MeshMixer^® to obtain the hollow AVM. (E) Schematization of the printing process to produce the physical model of the vascular AVM. (F) Representation of the complete phantom constituted by the AVM embedded into the silicone-based cube, fitting the commercial anthropomorphic phantom. 3D, three-dimensional; AVM, arteriovenous malformation; CT, computed tomography; DECT, double energy computed tomography.

FIG. 2.

(A) Picture of the CBCT Electron Density Phantom employed to generate the calibration curve for the assessment of the test materials' tissue-equivalence. (B) A CT scan of the phantom. (C) Calibration curve relating the standard inserts rED and CT numbers (WL 46, WW 1068). CBCT, cone beam computed tomography; CT, computed tomography; rED, relative electronic density.

FIG. 3.

(A) AVM model straight after printing and (B) after removal of supports. (C) AVM filled with an aqueous solution containing a blue dye. AVM, arteriovenous malformation; CT, computed tomography.

FIG. 4.

3D reconstruction, axial and sagittal CT scans of the SLA-printed phantom sealed with lids and immersed into a water vat. In (A) to (C) the phantom was empty, whereas in (D) to (F), it was filled with the contrast agent solution. CT, computed tomography; SLA, stereolithography.

FIG. 5.

(a) AVM model printed with SLA and embedded in PDMS without (A) and with (B) the presence of the contrast agent in the vessels. AVM, arteriovenous malformation; CT, computed tomography; PDMS, polydimethylsiloxane.

FIG. 6.

(A) Experimental setup for the validation of the AVM phantom embedded in PDMS filled with the contrast agent and fitted into the anthropomorphic phantom. (B) Sagittal, (C) coronal, and (D) axial CT scans of the phantom. AVM, arteriovenous malformation; CT, computed tomography; PDMS, polydimethylsiloxane.

FIG. 7.

(A) AVM structure of the patient, isolated, modeled, and postprocess directly form CT images compared with (B) the 3D reconstruction of the AVM elaborated from CT data acquired using our phantom. AVM, arteriovenous malformation; CT, computed tomography.