Novel Design of Implantable Esophageal Stent to Reduce the MRI RF-Induced Heating

In this work, the magnetic resonance imaging (MRI) radio frequency (RF)-induced heating mechanism for an esophageal stent is discussed from the prospective of forward scattering and the reciprocity theorem. We conclude that the RF-induced heating largely depends on the induced currents on the surface of the stent. Based on this understanding, a novel implantable segmented stent structure is developed to reduce the RF-induced heating of an esophageal stent under MRI procedures. By using a segmented structure, the specific absorption rate (SAR) for a 10-mm-radius and 98-mm-length stent decreased from 53.0 to 14.2 W/kg at a whole-body average SAR of 2 W/kg, and the maximum temperature rise over 15-min MRI exam is reduced from 4.52 to 1.72 degrees C. The simulated results and experimental measurements agree with each other within the combined uncertainty and demonstrate the effectiveness of the structured stent design. Related to RF-induced heating, this novel design can be used to develop inherently safe esophageal stents.