title: RF field visualization of RF ablation at the Larmor frequency.
abstract: Radio-frequency ablation (RFA) is an effective minimally invasive treatment for tumors. One primary source of difficulty is monitoring and controlling the ablation region. Currently, RFA is performed at 460 kHz, for which magnetic resonance imaging (MRI) could play a role given its capability for temperature monitoring and tumor visualization. If instead the ablation were to be performed at the MRI Larmor frequency, then the MR capability for B(1) field mapping could be used to directly visualize the radio-frequency (RF) fields created by the ablation currents. Visualizing the RF fields may enable better control of the ablation currents, enabling better control of lesion shape and size and improving repeatability. We demonstrate the feasibility of performing RFAs at 64 MHz and show preliminary results from imaging the RF fields from the ablation. The post-ablation RF fields show an increase in current density in the ablated region, consistent with an increase in conductivity of the ablated tissue.
authors.affiliation: Electrical Engineering Department, Stanford University, CA 94305, USA. kshultz@mrsrl.stanford.edu
authors.forename: Kim
authors.initials: K
authors.lastname: Shultz
authors.forename: Pascal
authors.initials: P
authors.lastname: Stang
authors.forename: Adam
authors.initials: A
authors.lastname: Kerr
authors.forename: John
authors.initials: J
authors.lastname: Pauly
authors.forename: Greig
authors.initials: G
authors.lastname: Scott
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology; D017115:Catheter Ablation / Q000379:methods*; D004553:Electric Conductivity; D004574:Electromagnetic Fields; D005240:Feasibility Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013552:Swine; D013817:Thermography / Q000379:methods