title: Potential for high-permittivity materials to reduce local SAR at a pacemaker lead tip during MRI of the head with a body transmit coil at 3 T.
abstract: To illustrate the potential for high permittivity materials to be used in decreasing peak local SAR associated with implants when the imaging region is far from the implant.
  
  
  
  We performed numerical simulations of a human subject with a pacemaker in a body-sized birdcage coil driven at 128 MHz with and without a thin (5 mm) shell of material of high electric permittivity around the head.
  
  
  
  For a shell with relative permittivity of 600, the maximum specific energy absorption rate averaged over any 1 g of tissue near the pacemaker was reduced by 73.5% for a given B1field strength at the center of the brain.
  
  
  
  Although further study is required, initial simulations indicate that strategic use of high permittivity materials may broaden the conditions under which patients with certain implants can be imaged safely. Magn Reson Med 78:383-386, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Radiology, New York University College of Medicine, New York, New York, USA.
authors.forename: Zidan
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guang Zhou, Guang Dong Province, China.
authors.forename: Xuegang
authors.initials: X
authors.lastname: Xin
authors.affiliation: Department of Radiology, New York University College of Medicine, New York, New York, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Collins
mesh_terms: D065638:Absorption, Radiation; D001672:Biocompatible Materials / Q000737:chemistry*; D001921:Brain / Q000000981:diagnostic imaging*; D017097:Electric Impedance; D004567:Electrodes, Implanted; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008422:Materials Testing; D010138:Pacemaker, Artificial; D000069079:Radiation Exposure / Q000032:analysis* / Q000517:prevention & control*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers; D051598:Whole Body Imaging / Q000295:instrumentation*
chemical_list: D001672:Biocompatible Materials
keywords: MRI; dielectric; pacemaker; permittivity; safety