In Vivo Evaluation of Magnetic Targeting in Mice Colon Tumors with Ultra-Magnetic Liposomes Monitored by MRI.

PURPOSE: The development of theranostic nanocarriers as an innovative therapy against cancer has been improved by targeting properties in order to optimize the drug delivery to safely achieve its desired therapeutic effect. The aim of this paper is to evaluate the magnetic targeting (MT) efficiency of ultra-magnetic liposomes (UML) into CT26 murine colon tumor by magnetic resonance imaging (MRI).

PROCEDURES: Dynamic susceptibility contrast MRI was applied to assess the bloodstream circulation time. A novel semi-quantitative method called %I0.25 , based on the intensity distribution in T2 * -weighted MRI images was developed to compare the accumulation of T2 contrast agent in tumors with or without MT. To evaluate the efficiency of magnetic targeting, the percentage of pixels under the intensity value I0.25 (I0.25  = 0.25(Imax  - Imin )) was calculated on the intensity distribution histogram.

RESULTS: This innovative method of processing MRI images showed the MT efficiency by a %I0.25 that was significantly higher in tumors using MT compared to passive accumulation, from 15.3 to 28.6 %. This methodology was validated by ex vivo methods with an iron concentration that is 3-fold higher in tumors using MT.

CONCLUSIONS: We have developed a method that allows a semi-quantitative evaluation of targeting efficiency in tumors, which could be applied to different T2 contrast agents.