MRI manifestation of novel superparamagnetic iron oxide nanoparticles in the rat inner ear.

Aim: Superparamagnetic iron oxide nanoparticles hierarchically coated with oleic acid and Pluronic F127 copolymers (POA@SPION) have shown exceptional 12 contrast enhancement. The aim of the present work was to investigate the MRI manifestation of POA@SPION in the inner ear. Materials & methods: A total of 26 male Wister rats were selected for testing POA@SPION administered through intracochlear, intratympanic and intravenous routes. MRI was performed with a 4.7 T MR scanner. Results & conclusion: POA@SPION can be introduced into the perilymph space, after which it becomes widely distributed and can demonstrate the integrity of the perilymph-endolymph barrier. Positive highlighting of the endolymph compartment against the darkened perilymph was visualized for the first time. POA@SPION passed through the middle-inner ear barriers in only small amounts, but stayed in the perilymph for 3 days. They did not traverse the blood-perilymph barrier or blood-endolymph barrier. The inner ear distribution of POA@SPION was confirmed by histology. POA@SPION is a promising T2 negative contrast agent.