CT and MRI compatibility of flexible 3D printed materials for soft actuators and robots used in image-guided interventions.

PURPOSE 3D printing allows for the fabrication of medical devices with complex geometries, such as soft actuators and robots that can be used in image-guided interventions. This study investigates flexible and rigid 3D printing materials in terms of their impact on multimodal medical imaging. METHODS The generation of artifacts in clinical CT and MR imaging was evaluated for six flexible and three rigid materials, each with a cubical and a cylindrical geometry, and for one exemplary flexible fluidic actuator. Additionally, CT Hounsfield units (HU) were quantified for various parameter sets iterating peak voltage, X-ray tube current, slice thickness and convolution kernel. RESULTS We found the image artifacts caused by the materials to be negligible in both CT and MR images. The HU values mainly depended on the elemental composition of the materials and applied peak voltage ranging between 80 kVp to 140 kVp. Flexible, non-silicone-based materials ranged between 51 HU and 114 HU. The voltage dependency was less than 29 HU. Flexible, silicone-based materials ranged between 60 HU and 365 HU. The voltage-dependent influence was as large as 172 HU. Rigid materials ranged between -69 HU and 132 HU. The voltage-dependent influence was less than 33 HU. CONCLUSION All tested materials may be employed for devices placed in the field of view during CT and MR imaging as no significant artifacts were measured. Moreover, the material selection in CT could be based on the desired visibility of the material depending on the application. Given the wide availability of the tested materials, we expect our results to have a positive impact on the development of devices and robots for image-guided interventions.