MR imaging of murine arthritis using ultrasmall superparamagnetic iron oxide particles☆

The objective of this work was to determine the ability of magnetic resonance (MR) imaging with ultrasmall superparamagnetic iron oxide (USPIO) particles to provide quantitative measures of inflammation in autoimmune arthritis. ere injected intravenously or intra-articularly with USPIO followed by magnetic resonance and histological assessment of the knee joint. Comparisons were made between MR microimages and histology in naı̈ve mice and mice with collagen-induced arthritis. ing intravenous administration, accumulation of USPIO was observed in the popliteal lymph nodes, but not the joint. Administration of USPIO intra-articularly resulted in signal loss in the joint. The MR signal intensity could be quantified and correlated with iron staining in the synovial lining. A marked increase in USPIO uptake and a corresponding decrease in signal intensity were observed in arthritic, compared to naı̈ve mice. Areas of focal signal loss corresponded to foci of iron staining by histology. studies may provide a basis for the clinical application of USPIO in arthritis for assessing disease severity and monitoring response to therapy.