Patent ID: 6251366
Filing Date: 2001-06-26
Classification: A61K,G01R

Abstract:
A dual purpose MRI contrast medium consisting essentially of an aqueous dispersion of superparamagnetic solid particles and at least one polyelectrolyte which acts as a dispersant, said polyelectrolyte having an average molecular weight of from 1,000 to 25,000 said superparamagnetic solid particles having a primary particle size of from 7 to 50 nm and a specific surface area of from 30 to 130 m.sup.2 /g and being present in the dispersions in the form of colloidal units with on average only one superparamagnetic solid particle enveloped by the polyelectrolyte, and said polyelectrolyte having a charge number greater than 5, with the proviso that the relaxivities of the contrast media are such that r.sub.1 is greater than 9.times.10.sup.4 M.sup.-1 s.sup.-1 and the ratio of r.sub.2 to r.sub.1 is at least 7, measured at 20 MHz and 37.degree. C.