Uptake characteristics of MRI and CT contrast agents in 3D printing materials for vascular phantoms

BACKGROUND: To determine the reusability and robustness of three 3D-printing materials for anatomical vessels by evaluating their contrast agent uptake characteristics throughout different timeframes. METHODS: The tested samples were 3D-printed cylindrical samples that have the same diameter and wall thickness as a healthy adult aorta. Three different materials of varying degrees of Shore hardness were used to print these samples on a Stratasys J850 Prime PolyJet 3D printer (VeroClear, Agilus, and an Agilus/VeroClear mixture). Each sample was filled with one of three contrast agent dilutions or a control solution. Samples remained filled with their respective solution for one week, one day, or one hour. Computed tomography (CT) and magnetic resonance (MR) images were taken of all 54 samples. The CT and MR images were evaluated to determine the diameters of the samples, as well as the radiodensity/signal intensity of the samples. An Intraclass Correlation Coefficient (ICC) was calculated to determine the degree of measurement variation between the investigators. Sample mass increase was determined by weighing samples before and after exposure to the solutions. A generalized linear mixed model (GLMM) was used to evaluate the contrast agent uptake behavior of the materials based on CT and MR imaging data. RESULTS: A small relative mass increase in the 3D-printed materials was noted: VeroClear showed mass increases of between 1.1% and 2.5%, which is in line with the respective data sheet. Agilus showed mass increases of 2.9% to 4.4%. In CT images, very small, but statistically significant effects were detected for VeroClear in the measured diameters (t = −2.31, p = 0.02) and the signal intensity (t = 3.40, p < 0.001). All other tested material combinations revealed no significant effects in comparison to the reference sample. CONCLUSIONS: This study suggests that the tested materials using the Stratasys J850 3D printer can produce structures that do not absorb clinically detectable amounts of CT or MR imaging contrast agent solutions. Thus, the tested materials are suitable for the 3D printing of vascular phantoms that are filled with contrast agent solutions and can be reused in the time periods evaluated.