title: Simple design changes to wires to substantially reduce MRI-induced heating at 1.5 T: implications for implanted leads.
abstract: Reductions in MRI-induced heating at 1.5 T resulting from a simple design change to coiled wires were investigated. MRI-induced heating was assessed for two different coiled wire forms (length, 26 cm): (1) multi-filar coiled wire form and (2) multi-filar coiled wire form having a different coiled pitch, providing an air gap spacing between adjacent five-filar coil loops. Each wire had an electrode and was insulated to create a lead, similar to that which would be used for a medical implant. The wire forms were placed in a gelled-saline-filled head/torso phantom and imaged at 1.5 T [whole-body average specific absorption rate (SAR), 1.79 W/kg]. Fluoroptic thermometry probes were used to measure temperatures at the distal ends of the wires. The experiments demonstrated a substantial reduction in MRI-induced heating for the modified wire compared to the unmodified wire (i.e., 10.5 degrees C difference observed in one experiment and 26 degrees C difference in another). These findings have important implications for MRI-induced heating of leads used for medical implants.
authors.affiliation: Biophan Technologies, Inc., West Henrietta, NY 14586, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Gray
authors.forename: W Timothy
authors.initials: WT
authors.lastname: Bibens
authors.forename: Frank G
authors.initials: FG
authors.lastname: Shellock
mesh_terms: D004559:Electric Wiring / Q000295:instrumentation*; D004567:Electrodes, Implanted; D004867:Equipment Design / Q000379:methods; D006358:Hot Temperature; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D013696:Temperature; D013997:Time Factors