A radiographic analysis of common 3D print materials and assessment of their fidelity within vertebral models

Introduction: The objective of this investigation is to examine a wide array of commonly accessible 3D print filaments and assess their radiographic fidelity in vertebral models. Material and methods: Solid cylinders were 3D printed on an Ultimaker S5 (Ultimaker B.V., Utrecht, Netherlands) in 12 commonly accessible filaments: ABS (Acrylonitrile butadiene styrene), PLA (Polylactic acid), Tough PLA, PP (Poly propylene), Carbon Fiber ABS, Wood fill, PETG (Polyethylene terephthalate glycol), Nylon, PC (Polycarbonate), Bronze fill, TPU 95A (Thermoplastic polyurethane), and CPE (Chlorinated polyethylene). Cylinders were imaged in a CT phantom with anatomic standards. Next, 11 identical L4 human vertebral models were 3D printed in the same materials (omission of TPU 95A). AP and lateral fluoroscopic images were taken of each of the vertebrae and sent to board-certified/board-eligible neurosurgeons, neuroradiologists, and orthopedic spine surgeons for evaluation. Results: CT imaging of the materials yielded a range of Hounsfield values from –120.6 HU (PP) to 167.76 HU (PETG). The polled experts rated CF ABS as the highest fidelity model (mean 4.069) and Bronze fill as lowest (mean 2.000). All simulated vertebrae in this study ranked higher than Bronze fill (p<0.05). Notably, CF ABS (p=0.0029), ABS (p=0.0075), and CPE (p=0.0182) ranked significantly higher than Tough PLA. Discussion: It was determined that CT values of examined filaments were not comparable to cortical bone standard but similar to other bone standards. Our results suggest that apart from Bronze fill, educators can create high fidelity fluoroscopic models with print materials such as ABS, CF ABS, and CPE.