Negative Magnetic Resonance Contrast of Peri-Aortic Lymph Nodes Created by Uptake of Ultrasmall Superparamagnetic Particles of Iron Oxide (USPIOs) May Mask the Aortic Lumen and Lead to False Positive Results with Regard to the Diagnosis of Atherosclerosis.

Bernard C. te Boekhorst¹, Sandra M. Bovens^1,2, Marcel G. Nederhoff^1,2, Kees W. van de Kolk¹, Maarten J. Cramer¹, Matthijs F. van Oosterhout³, Michiel ten Hove¹, Pieter A. Doevendans¹, Gerard Pasterkamp¹, Cornelis J. van Echteld¹

The strong T2* shortening effect of USPIOs leading to the effect of glooming and the uptake of USPIOs in lymph nodes adjacent to the aorta may pose limits to their use as contrast agent for visualization of atherosclerotic plaque in the aorta in animal models. We show a strong T2* and T2 effect of USPIOs uptaken in the para-aortic lymph nodes on MR images, which probably masks any effect of plaque uptake of USPIOs. With histology, when compared with lymph node uptake of USPIOs, hardly any uptake of USPIOs in plaque is observed 120 hours after administration.