Novel method for imaging biodegradable polymeric microparticles using MRI: application toward monitoring drug delivery

We have developed a novel, non-invasive method to monitor intravesical drug delivery to the bladder using MRI by encapsulating Gd-DTPA into biodegradable polymeric microparticles. In in vitro experiments, Gd-DTPA-loaded particles could be differentiated from blank particles and water. Images from in vivo experiments demonstrated that particle distribution in the bladder could be assessed and that signal intensity appeared to correspond with particle population. The microparticles were adherent to the urothelium and were detectable by MRI for at least 4 days after the initial instillation due to their muco-adhesiveness and stability. This non-invasive method enables the evaluation of local particle distribution in vivo, thereby enhancing the value of particle-based drug delivery systems.