Ferumoxides (SPIO)

Endorem, also known as Ferumoxides, is a superparamagnetic iron oxide (SPIO) nanoparticle contrast agent used in magnetic resonance imaging (MRI) to enhance the detection of liver and spleen lesions (NIH, 2022; mr-tip.com). It consists of iron oxide cores coated with dextran, which facilitates its uptake by the reticuloendothelial system (RES), particularly the Kupffer cells in the liver (NIH, 2022). Upon intravenous administration, these nanoparticles are phagocytosed by healthy RES cells, leading to a significant reduction in T2 and T2* relaxation times and a subsequent darkening of normal tissue on MRI scans (mr-tip.com). In contrast, malignant tissues such as metastases or primary liver tumors typically lack Kupffer cells and do not take up the agent, appearing relatively hyperintense against the darkened healthy parenchyma (NIH, 2022). This differential signal intensity improves the diagnostic accuracy for identifying hepatic malignancies and other focal lesions. While historically significant for liver imaging, the clinical use of Endorem has declined as newer contrast agents and imaging protocols have been developed. Safety concerns associated with its use include transient back pain, flushing, and rare hypersensitivity reactions (NIH, 1995).

Other names

EndoremFeridexAMI-25Superparamagnetic iron oxide nanoparticlesSPIO

Ferumoxides are superparamagnetic iron oxide nanoparticles that are sequestered by the phagocytic Kupffer cells of the reticuloendothelial system (RES) (NIH, 2022). This sequestration leads to a decrease in T2 and T2* relaxation times, resulting in a loss of signal intensity (darkening) in normal liver and spleen tissue on MRI, which enhances the contrast against lesions that do not contain Kupffer cells (mr-tip.com).