title: Evaluation of MRI issues at 3-Tesla for a transcatheter aortic valve replacement (TAVR) bioprosthesis.
abstract: OBJECTIVE
  Replacement of the aortic heart valve typically requires open-heart surgery. A new transcatheter aortic valve replacement (TAVR) bioprosthesis made from metallic material was recently developed that is an advantageous alternative insofar as it is implanted using a minimally invasive procedure. Because of the presence of metal, there are safety issues related to MRI. Therefore, the purpose of this study was to use standardized testing techniques to evaluate MRI issues for this TAVR bioprosthesis in association with a 3-Tesla MR system.
  
  
  METHODS
  The TAVR bioprosthesis (Hydra Aortic Valve, Percutaneous Heart Valve Prosthesis, Vascular Innovations Company, Ltd, Thailand) was evaluated for magnetic field interactions (translational attraction and torque), MRI-related heating at a relative high specific absorption rate level (whole body average SAR, 2.9-W/kg), and artifacts (T1-weighted, spin echo, and gradient echo pulse sequences) at 3-Tesla.
  
  
  RESULTS
  The TAVR bioprosthesis demonstrated negligible magnetic field interactions (deflection angle, 3-degrees; torque, 0) and minimal heating (maximum temperature rise, 2.5°C; background temperature rise, 1.7°C). Artifacts were relatively small in relation to the size and shape of the implant.
  
  
  CONCLUSIONS
  The TAVR bioprosthesis that was evaluated in this investigation is acceptable, or using current MRI terminology "MR Conditional", for a patient undergoing MRI at 3-Tesla or less.
authors.affiliation: Loyola Marymount University, 1 LMU Drive, Los Angeles, CA 90045. Electronic address: msaeedi23@hotmail.com.
authors.forename: Mahrad
authors.initials: M
authors.lastname: Saeedi
authors.affiliation: Loyola Marymount University, 1 LMU Drive, Los Angeles, CA 90045. Electronic address: asishthomas77@gmail.com.
authors.forename: Asish
authors.initials: A
authors.lastname: Thomas
authors.affiliation: Keck School of Medicine, University of Southern California and Institute for Magnetic Resonance Safety, Education, and Research, Playa Del Rey, CA 90293. Electronic address: frank.shellock@mrisafety.com.
authors.forename: Frank G
authors.initials: FG
authors.lastname: Shellock
mesh_terms: D065638:Absorption, Radiation; D001021:Aortic Valve / Q000473:pathology* / Q000601:surgery; D016477:Artifacts; D001705:Bioprosthesis; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D025321:Surgery, Computer-Assisted / Q000379:methods; D013696:Temperature; D065467:Transcatheter Aortic Valve Replacement / Q000295:instrumentation* / Q000379:methods
keywords: MRI, artifacts; MRI, implants; MRI, safety; Specific absorption rate, SAR