title: Ex vivo evaluation of ferromagnetism, heating, and artifacts produced by heart valve prostheses exposed to a 1.5-T MR system.
abstract: Ex vivo testing techniques were used to determine the ferromagnetic qualities of, presence of heating in, and artifacts produced by 13 different heart valve prostheses exposed to a 1.5-T (64-MHz) magnetic resonance (MR) system. None of the heart valve prostheses showed a measurable deflection in the 1.5-T static magnetic field. Only minimal artifacts were produced during MR imaging with a fast spoiled GRASS (gradient-recalled acquisition in the steady state) pulse sequence. The largest temperature changes measured during a "worst case" MR imaging sequence (estimated average specific absorption rate, 2.5 W/kg; estimated spatial peak specific absorption rate, 7.6 W/kg) were +0.2 degree C with the implant imaged "in air" and +0.3 degrees C with the implant imaged in normal saline. Therefore, MR procedures performed with a 1.5-T (64-MHz) MR system may be performed safely in patients with any of the 13 different heart valve prostheses evaluated in this study.
authors.affiliation: Tower Imaging, Los Angeles, CA 90048.
authors.forename: F G
authors.initials: FG
authors.lastname: Shellock
authors.forename: S M
authors.initials: SM
authors.lastname: Morisoli
mesh_terms: D000042:Absorption; D016477:Artifacts; D001672:Biocompatible Materials / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D055590:Electromagnetic Phenomena; D005069:Evaluation Studies as Topic; D006350:Heart Valve Prosthesis; D006358:Hot Temperature; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008280:Magnetics; D008422:Materials Testing; D011474:Prosthesis Design; D013314:Stress, Mechanical; D013997:Time Factors; D014025:Titanium / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; C009139:pyrolytic carbon; D002244:Carbon; D014025:Titanium