Targeted Delivery of Contrast Agents to the Tympanic Medial Wall at Minimum Amount and the Efficient Uptake in the Inner Ear through Oval and Round Windows

Inner ear MRI after intratympanic administration of Gadolinium chelate (GdC) has become a valuable method in detecting endolymphatichy drops attributing to the efficient uploading in the inner ear while avoiding high dose intravenous application that can cause renal injury. In addition to the well-accepted round window pathway, the oval window was discovered as a dominant approach for the agents to move from the middle ear into the inner ear. In order to fine-tune this method, a targeted delivery of GdC to the medial wall of the middle ear cavity was developed in a minimally invasive way. The targeted tympanic medial wall administration was expended in the topical tympanic application of super paramagnetic iron oxide nanoparticles and manganese as contrast agents in the inner ear MRI. This review provides an overview of the developments in the field.