title: Assessment of Vascular Stent Heating with Repetitive Transcranial Magnetic Stimulation.
abstract: OBJECTIVE
  A high proportion of patients with stroke do not qualify for repetitive transcranial magnetic stimulation (rTMS) clinical studies due to the presence of metallic stents. The ultimate concern is that any metal could become heated due to eddy currents. However, to date, no clinical safety data are available regarding the risk of metallic stents heating with rTMS.
  
  
  METHODS
  We tested the safety of common rTMS protocols (1 Hz and 10 Hz) with stents used commonly in stroke, nitinol and elgiloy. In our method, stents were tested in gelled saline at 2 different locations: at the center and at the lobe of the coil. In addition, at each location, stent heating was evaluated in 3 different orientations: parallel to the long axis of coil, parallel to the short axis of the coil, and perpendicular to the plane of the coil.
  
  
  RESULTS
  We found that stents did not heat to more than 1°C with either 1 Hz rTMS or 10 Hz rTMS in any configuration or orientation. Heating in general was greater at the lobe when the stent was oriented perpendicularly.
  
  
  CONCLUSIONS
  Our study represents a new method for ex vivo quantification of stent heating. We have found that heating of stents was well below the Food and Drug Administration standards of 2°C. Thus, our study paves the way for in vivo testing of rTMS (≤10 Hz) in the presence of implanted magnetic resonance imaging-compatible stents in animal studies. When planning human safety studies though, geometry, orientation, and location relative to the coil would be important to consider as well.
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Nicole
authors.initials: N
authors.lastname: Varnerin
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: David
authors.initials: D
authors.lastname: Mirando
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Kelsey A
authors.initials: KA
authors.lastname: Potter-Baker
authors.affiliation: Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York.
authors.forename: Jesus
authors.initials: J
authors.lastname: Cardenas
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio; Department of Human Performance and Engineering, Kessler Institute for Rehabilitation, West Orange, New Jersey.
authors.forename: David A
authors.initials: DA
authors.lastname: Cunningham
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Vishwanath
authors.initials: V
authors.lastname: Sankarasubramanian
authors.affiliation: Center for Neurological Restoration, Neurosurgery, Neurological Institute, Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Erik
authors.initials: E
authors.lastname: Beall
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio; Department of Physical Medicine and Rehabilitation, Neurological Institute, Cleveland Clinic Foundation, Cleveland, Ohio. Electronic address: plowe2@ccf.org.
authors.forename: Ela B
authors.initials: EB
authors.lastname: Plow
mesh_terms: D000497:Alloys; D002858:Chromium Alloys; D003035:Cobalt; D057510:Endovascular Procedures / Q000009:adverse effects / Q000295:instrumentation*; D019544:Equipment Failure Analysis; D006361:Heating; D006801:Humans; D008422:Materials Testing; D011474:Prosthesis Design; D011475:Prosthesis Failure; D018570:Risk Assessment; D015607:Stents; D020521:Stroke / Q000628:therapy*; D065908:Transcranial Direct Current Stimulation / Q000009:adverse effects
chemical_list: D000497:Alloys; D002858:Chromium Alloys; C013616:nitinol; D003035:Cobalt
keywords: Stent; implant; magnetic field; rTMS; stroke; temperature