title: On the RF heating of coronary stents at 7.0 Tesla MRI.
abstract: OBJECTIVE
  Examine radiofrequency (RF) induced heating of coronary stents at 7.0 Tesla (T) to derive an analytical approach which supports RF heating assessment of arbitrary stent geometries and RF coils.
  
  
  METHODS
  Simulations are performed to detail electromagnetic fields (EMF), local specific absorption rates (SAR) and temperature changes. For validation E-field measurements and RF heating experiments are conducted. To progress to clinical setups RF coils tailored for cardiac MRI at 7.0T and coronary stents are incorporated into EMF simulations using a human voxel model.
  
  
  RESULTS
  Our simulations of coronary stents at 297 MHz were confirmed by E-field and temperature measurements. An analytical solution which describes SAR(1g tissue voxel) induced by an arbitrary coronary stent interfering with E-fields generated by an arbitrary RF coil was derived. The analytical approach yielded a conservative estimation of induced SAR(1g tissue voxel) maxima without the need for integrating the stent into EMF simulations of the human voxel model.
  
  
  CONCLUSIONS
  The proposed analytical approach can be applied for any patient, coronary stent type, RF coil configuration and RF transmission regime. The generalized approach is of value for RF heating assessment of other passive electrically conductive implants and provides a novel design criterion for RF coils.
authors.affiliation: Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.
authors.forename: Lukas
authors.initials: L
authors.lastname: Winter
authors.affiliation: Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Oberacker
authors.affiliation: Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.
authors.forename: Celal
authors.initials: C
authors.lastname: Özerdem
authors.affiliation: Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.
authors.forename: Yiyi
authors.initials: Y
authors.lastname: Ji
authors.affiliation: Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.|Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: von Knobelsdorff-Brenkenhoff
authors.affiliation: Physikalisch Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Weidemann
authors.affiliation: Physikalisch Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Ittermann
authors.affiliation: Physikalisch Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Seifert
authors.affiliation: Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.|Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.
authors.forename: Thoralf
authors.initials: T
authors.lastname: Niendorf
mesh_terms: D004574:Electromagnetic Fields; D006358:Hot Temperature; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects*; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D011846:Radio Waves; D015607:Stents; D062125:Thermometry
keywords: RF heating; RF power deposition; coronary stents; specific absorption rate; ultrahigh field MR