Time-course characterization of an aqueous colloidal polydisperse contrast agent in mice using micro-computed tomography

Abstract

Background: Evaluation of cardiovascular function in mice using micro-CT requires that a contrast agent (CA) be administered to differentiate the blood from the myocardium. eXIA 160, an aqueous colloidal poly-disperse CA with a high concentration of iodine (160mg I/mL), creates strong contrast between blood and tissue with a low injection volume. In this study, the blood-pool enhancement time-course of eXIA 160 is monitored over a 24-hour period to determine its optimal use during cardiac function studies. Methods/Results: 8-second scans were performed (80kVp, 110mA) using the GE Locus Ultra micro-CT scanner. Male mice (black, 22-24g) were injected via tail vein with 5 μL/g body weight eXIA 160 (Binitio Biomedical Inc.). A precontrast scan was performed; following injection, mice were scanned at 15, 30, 45, and 60 minutes, 2, 4, 8, 24, and 48 hours. Overall, the highest contrast in the left ventricle occurred at 5 minutes (687 HU). Uptake of the CA by the myocardium was also observed: myocardial tissue showed increasing enhancement over a 4-hour period, remaining even once the contrast was eliminated from the vasculature. Conclusion: eXIA 160 provided high contrast between blood and myocardial tissue for a period of 30 minutes following injection. Notably, this CA was also taken up by the myocardium and provided continued enhancement when the contrast agent was eliminated from the blood, making LV wall function studies possible. In conclusion, eXIA 160, with its high iodine concentration and targeted tissue uptake characteristics, make it an ideal agent to use when evaluating cardiovascular function in mice.