Computed Tomography of Polymeric Biomedical Implants from Bench to Bedside

Abstract

Implanted biomedical devices require porosity to encourage tissue regeneration. However, characterizing porosity, which affects many functional device properties, is non-trivial. Computed tomography (CT) is a quick, versatile, and non-destructive way to gain 3D structural information. While optimization of CT for polymeric devices has been investigated at the bench on high-resolution micro-CT (μCT) scanners, pre-clinical and clinical systems cannot be tuned the same way, given an overriding objective to minimize ionizing radiation exposure to living tissues. Therefore, in this study we tested feasibility of obtaining structural information in pre-clinical systems and μCT under physiological conditions. The size of resolved features in porous structures is highly dependent on the resolution (voxel size) of the scan. Lower resolution underestimated porosity and overestimated pore size. With the homogeneous introduction of radiopaque nanoparticle contrast agent into both biopolymers and synthetic polymers, devices could be imaged in the hydrated state, even at high-resolution. Biopolymers had significant structural changes at the micro-scale post-hydration, including a mean increase of 130% in pore wall thickness that could potentially impact biological response. Through optimizing devices for medical imaging, CT has the potential to be a facile way to monitor devices from initial design stages through to clinical translation.