3D printing complex lattice structures for permeable liver phantom fabrication

Abstract

Liver cancer is currently the third deadliest cancer in the world, affecting over 700,000 people per year. To improve early detection of tumours, perfusion testing is used for imaging of blood flow in the liver. Creating a phantom to accurately mimic the liver in imaging techniques such as Dynamic Contrast-enhanced (DCE) computed tomography (CT) will improve testing and calibration of different imaging protocols and pharmacokinetic perfusion models. In current literature, there lacks a permeable, easily producible and reusable liver phantom for dynamic contrast-enhanced CT perfusion testing. This study details the production of phantoms with controllable permeability for standardization in hepatic perfusion using commercially available 3D printing methods. Phantoms with hexagonal channels were designed in nTopology Element and printed in materials with a density of 0.9–1.5 g/cm3. Polylactic acid was selected for fused deposition modelling (FDM), while proprietary resins were used for an inkjet printing process called MultiJet Printing (MJP). Permeability tests were performed on samples to observe flow rates obeying Darcy's Law. Scanning electron microscopy (SEM) was used to analyze pore size in FDM and MJP samples, while micro-CT scans were performed to analyze pore interconnectivity. The collected permeability data exceeds reported literature values of 0.0167 mL s−1 cm2 and approach the desired range of 0.15–0.3 mL s−1 cm2. Micro-CT scans show obstructions from the MJP printing process. SEM images were analyzed in Fiji and showed varying results for FDM printing. Future work will involve reducing pore size while maintaining high permeability. Using 3D printing in phantom development will help create adaptable, reliable and permeable phantoms for diagnostic imaging.