Exploring VivoVist™ for ex vivo micro-CT imaging of mouse vasculature

This study aims to develop a simpler, quicker, and more effective method for ex vivo vascular imaging using VivoVist™, a barium-based micro-CT contrast agent, combined with an anticoagulant. VivoVist™ (Nanoprobes, Inc.) is a commercially available contrast agent that enables rapid and uniform vascular distribution due to its high-water solubility. While previous studies demonstrated its utility for in vivo photon-counting micro-CT, this work evaluates its application in ex vivo imaging as a potential replacement for the lead-based contrast agent MicroFil. Three mice with APOE genotypes were imaged using three distinct preparation protocols. Two mice were scanned with an Energy-Integrating Detector (EID) at 22 μm resolution, while the third underwent imaging at 65 μm on a photon-counting CT (PCCT) system with material decomposition capabilities. The results confirm that VivoVist™ provides excellent vascular contrast, enabling detailed visualization of vascular structures in key organs such as the lung, liver, heart, and brain. The material decomposition from PCCT enabled segmentation-free vascular separation, which is crucial for applications such as identifying atherosclerotic plaques. The imaging outcomes suggest that a fixative is not always necessary, highlighting the potential for a simplified, reproducible protocol. VivoVist™ streamlines imaging workflows by reducing procedural complexity and eliminating the extensive post-mortem steps required for MicroFil. These findings establish VivoVist™ as a useful alternative for ex vivo vascular imaging and highlight the synergy between VivoVist™ and photon-counting CT for advanced preclinical imaging studies.