Evaluation of metal nanoparticle- and plastic resin-based x-ray contrast agents for kidney capillary imaging

Abstract

Injection of radiopaque substances into the vasculature followed by post mortem high resolution X-ray μCT imaging currently remains the primary means for capillary imaging in soft tissue. Commercial contrast agents for in vivo applications are, however, typically small molecular compounds that can easily diffuse across the blood vessel walls, which makes them unsuitable for ex vivo high resolution X-ray μCT imaging. We evaluated the suitability for kidney capillary imaging of the nanoparticle-based blood pool contrast agents Aurovist 15 nm and ExiTron nano 12000, along with the vascular casting resin μAngiofil, by post mortem imaging of whole mouse kidneys with 4-5 μm voxel size using the laboratory source μCT system Nanotom m. Based on the results, we identified specific obstacles to reliable capillary filling in the kidney, which will aid in the development of next-generation X-ray contrast agents and protocols.