Antitumor effects of the combination of magnetohydrodynamic thermochemotherapy and magnetic resonance tomography

Fe₃O₄ nanoparticles were coated with a layer of citric acid, forming coordination bonds between citrate ions and iron ions. The resulting aqueous citrate ferrite colloid was used as a T₂-weighted MRI negative contrasting agent. Sequential i.v. doses of citrate ferrite and Magnevist led to increases in MRI image contrast for 40 h and brightness for 30 min; scanning using a Bruker Biospec BC 70/30 USR biospectrotomograph yielded enhanced MRI images. This enhancement of MRI images was used to monitor oncogenesis during magnetohydrodynamic thermochemotherapy (MT) of mammary adenocarcinoma Ca 755 in female C57Bl/6j mice. Dextran ferrite colloid containing cyclophosphamide was tested as a magnetically directed antitumor agent using MT. Treatment of non-infiltrating tumors of volume ≈ 30 mm³ with six sessions of MT each lasting 30 min at 46°C led to 40% tumor regression and 300% increases in survival time. Treatment of infiltrating tumors of volume ≈ 300 mm³ in the same conditions yielded a 200% increase in survival time.