A longitudinal study of R2* and R2 magnetic resonance imaging relaxation rate measurements in murine liver after a single administration of 3 different iron oxide-based contrast agents.

OBJECTIVE: The objective of this study was to investigate the duration of R2* and R2 enhancement in murine liver in vivo after administration of a single dose of 3 different iron oxide-based contrast agents.
MATERIALS AND METHODS: Murine liver R2* and R2 were quantified longitudinally postadministration of 2.5 mgFe/kg ferumoxides, 2.5 mgFe/kg ferumoxytol, 2.5 or 5 mgFe/kg feruglose, or saline over 50 days. Changes in R2* and R2 were evaluated histologically using Perl's staining and by atomic absorption spectrometry.
RESULTS: All 3 contrast agents significantly increased liver R2* and R2 4 hours after challenge. After 10 days, R2* and R2 for both the ferumoxides and ferumoxytol cohorts had recovered to saline control levels, whereas the faster R2* and R2 of the feruglose cohort was sustained and significantly faster than control at day 50. Histology revealed feruglose in both Kupffer and endothelial cells, whereas both ferumoxides and ferumoxytol were associated with the Kupffer cells.
CONCLUSION: Compared with ferumoxides and ferumoxytol, feruglose exhibits prolonged R2* and R2 enhancement of murine liver.