Magnetic fluids in the blood

Recently, several medical applications have been proposed for magnetic fluids. These applications, which are reviewed here, involve introduction of magnetic fluids into the blood with subsequent magnetic guidance or magnetic detection by external devices. The issues associated with achieving magnetic guidance and minimizing toxicity are considered. The technical difficulties involved in any of the proposed applications are substantial, and would appear to outweigh the potential advantages at the present time. However, the research and development efforts in this area have been very limited and, therefore, the opportunities for innovation and further progress are significant.