CONTRAST AGENT COMPRISING ALGINATE AND AN ISOTOPE OR PARAMAGNETIC ION

摘要

A system for the delivery of contrast agents such as manganese (MR-active Mn²⁺ or other manganese isotopes) into extravascular body compartments in living subjects (mammals, amphibians, fish etc.) is described. The compound consists of alginate, manganese ions and other stabilizing ions (Ba²⁺, Ca²⁺ etc.) in a gel, formed by mixing of alginate and solutions of the ions mentioned above. The primary alginate used in production of the compound can be adjusted in structure (M- and G-block content and sequence), molecular weight and concentration. In addition, the salt solution and concentration can be varied in order to produce alginate gels of variable manganese amount (dose) and local manganese release rate (dose-rate). When injected or implanted into extravascular body compartments manganese ions will be released from the gel by ion exchange with body fluids and passive diffusion. Once released the manganese ions shortens the longitudinal MR relaxation time of water molecules in their vicinity amounting to positive image contrast in T1-weighted MR images. Furthermore, the compound may also act as slow release agent for positron emission tomography scanning, provided the manganese-isotope is emitting positrons (^m52mMn).