MRI evaluation of an atrial-anchored transcatheter mitral valve replacement implant

Abstract

OBJECTIVE. A medical implant that is made from metal must undergo proper MRI testing to ensure patient safety. The purpose of this investigation was to assess issues with MRI with a newly developed atrial-anchored transcatheter mitral valve replacement (TMVR) implant. MATERIALS AND METHODS. The atrial-anchored TMVR implant underwent an in vitro evaluation for MRI safety issues using standardized techniques and well-accepted methods. Magnetic field interactions including translational attraction and torque and artifacts were tested at 3 T. MRI-related heating was assessed at 1.5 T/64 MHz and 3 T/128 MHz using numeric simulations with analytical modeling and experimental testing. RESULTS. The atrial-anchored TMVR implant exhibited minor magnetic field interactions (9° deflection angle and no torque) at 3 T. The findings from the numeric simulations with analytical modeling were used to guide the placement of the implant in the phantom for the heating test and to identify the position on the implant that would result in the highest temperature rise. The highest temperature elevations recorded for the TMVR implant obtained on MRI at 1.5 T/64 MHz and 3 T/128 MHz were 2.7°C and 2.4°C, respectively. The maximum artifact size seen on a gradient echo pulse sequence extended approximately 5 mm relative to the size of the implant. CONCLUSION. The results of the tests performed on the atrial-anchored TMVR implant revealed no substantial concerns with respect to the conditions used in this investigation. Therefore, a patient with this new implant can safely undergo MRI by following the specific conditions defined by this study. The implant was deemed MR Conditional.