Design and Evaluation of Resistively Tapered Cylindrical Leads to Mitigate MRI-Induced RF Heating: Construction, In...

Active implantable medical devices (AIMDs), such as deep brain stimulation (DBS) systems, often include elongated conductive leads that can undergo significant heating during magnetic resonance imaging (MRI). The radiofrequency (RF) field of the scanner couples to these leads, creating substantial heating at the lead tips and posing a risk to surrounding tissue. This study builds on our recent work in evaluating a novel lead design that strategically varies conductivity along its length to reduce RF-induced heating during MRI at 1.5 T. We fabricated thickly-insulated resistively tapered cylindrical (RTC) wires with discrete conductivity transitions and employed transfer function methodology to predict their in vivo temperature rises during MRI. These predictions were validated through in vitro experiments. Under a 1.5 T MRI scanner $\left({B_1^ + = 4.2\mu {\text{T}}}\right)$, the RTC wire exhibited significantly lower RF heating compared to a uniformly coated wire, both in straight (0.84 ± 0.23 °C vs. 1.06 ± 0.38 °C) and looped (0.16 ± 0.13 °C vs. 0.24 ± 0.22 °C) trajectories. Comparison with a commercially available DBS lead showed an even larger reduction in RF heating, with the standard lead's RF heating reaching 36.6 ± 12 °C for straight and 6.1 ± 4.9 °C for looped trajectories. These findings suggest that leads with carefully tailored conductivity could enable safer MRI procedures for patients with AIMDs.Clinical relevance-This demonstrates that leads with strategically varied conductivity can significantly reduce MRI-induced tip heating in patients with active implantable device leads, thereby enhancing patient safety and expanding access to diagnostic imaging.