- In 2003 Dextran coated ultra small superparamagnetic iron oxide particles (USPIO), also known as Ferumoxtran-10 (Combidex , AMAG Pharmaceuticals, Inc. Lexington, MA, US) was shown to localize lymph node metastases with much greater accuracy than unenhanced MRI. Although a large study in prostate cancer was successful, an FDA Advisory Panel did not recommend approval and the company abandoned the agent.