| abstract |
Particles comprising a magnetically responsive material, preferably magnetite, and a dispersant, preferably dextran, wherein at least 90% of said particles have a particle size range of about 2 to about 10 nm are described, together with a method for their preparation, comprising admixing a magnetically responsive material with a dispersant to form an admixture, conveniently suspended in a gel phase, and contacting said first admixture with a base, such as ammonium hydroxide, for a time period and under conditions appropriate to form a magnetically responsive material-dispersant particle. n The use of the particles for a method of diagnosis comprising administering to a mammal a contrast effective amount of these particles suspended or dispersed in a physiologically tolerable carrier with generation of an NMR image of the mammal is also described. |