[Organ specific MRI contrast media in general practice].

Conventional MR imaging with non-specific gadolinium contrast agents is useful in the detection and staging of malignancies. With the development of organ-specific MR contrast agents, MR imaging is assuming an even larger role in body imaging. Two different classes of liver-specific agents, hepato-biliary agents targeted to the hepatocytes, and reticulo-endothelial agents (or Kupffer cell agents) targeted to the reticuloendothelial system in the liver and spleen, have been developed. MRI with liver-specific contrast agents is superior to helical CT for detection of liver metastases. Mangafodipir, which was originally developed as a liver-specific agent, has been shown to accumulate in the pancreas as well. Recent studies have revealed that mangafodipir-enhanced MRI is at least equal to spiral CT in the staging of pancreatic cancer and may be superior to CT in the detection of small cancers. Blood-pool contrast agents with a long blood half-life, such as ultrasmall iron oxide particles (USPIO), have been developed for MR angiography. After the clearance from the vascular system, USPIO are taken up by phagocytes and accumulate in normal lymph, but not in metastatic nodes. This effect can be exploited to increase the accuracy of MRI in lymph node staging of cancer of head-neck, lung or pelvis. In conclusion, various organ-specific MR contrast agents with a wide range of clinical applications have been developed. Future studies will demonstrate the role of contrast-enhanced MRI in comparison with multi-detector array CT.