Intravenous administration of ultrasmall superparamagnetic iron oxide particles (USPIO) as a po- tential contrast medium for MR lymph node structure imaging was tested. An appropriate experi- mental protocol of an animal experiment in rabbits was complemented. The relaxometric studies in vitro and ex vivo were carried out and a significant decrease of MR signals of the nodes was proved. The results obtained confirm that after intravenous administration of USPIO this contrast medium is selectively checked and stored in reticuloendothelial tissue of lymph nodes and thus causes a decrease of the normal T2 relaxation times and MR signal. The appropriate documentation is presented. The authors initial experience confirms impact of tissue specific USPIO contrast agent administration on MR imaging of lymph node structures and their diagnostic impact.

        Key words: diagnostic imaging - MR lymphography - MRI contrast agents