Fabrication of anatomical sonographic phantoms through direct 3D-printing.

Objectives: Sonographic anatomy classes can be curtailed by the availability of subjects for sensitive regional scanning. These limitations can be overcome by using anatomically realistic ultrasound phantoms (USPs). Simulation-based training with USPs also allows interventional radiology (IR) trainees to safely practice complex procedures. However, commercial phantoms are not patient-specific and involve costly, lengthy production methods. We describe a simple method for producing anatomically realistic USPs from 2D grey-scale ultrasound images using rapid direct 3D-printing technology. Methods: Original sonographic images were obtained from an open-source database and by scanning student volunteers. Images were digitally modified using Inkscape, ImageJ, Blender, Meshmixer, and CHITUBOX software programs. Models were printed using resin photopolymer 3D printers. In total, 4 phantoms were made: a femoral trochlea, a pediatric appendix, an eye with retinal detachment, and a radial nerve/brachioradialis model. The ImageJ Fiji plugin function, "Block Matching Correspondences" (BMCs) was used to assess similarity between source and phantom images. Results: All phantom images displayed BMCs with the original images (14%-43% similarity). The radial nerve model displayed the highest similarity. USPs produced with a hydrophilic swellable resin could be imaged throughout their full thickness and penetrated by a needle. Conclusions: In summary, this approach can manufacture USPs from 2D ultrasound data capable of generating anatomically accurate, patient-specific sonographic images. The low cost of these models, alongside their reproducibility through rapid 3D-printing technology, makes them a highly accessible, effective tool for simulation-based IR training. Advances in knowledge: To our knowledge, this study presents the first anatomical USPs, which have been directly 3D-printed from a single 2D ultrasound image source.