RF Heating Study of a New Medical Implant Lead for 1.5 T, 3 T, and 7 T MRI Systems

In the presence of an electrically conducting medical lead, radio frequency (RF) coils in magnetic resonance imaging (MRI) systems may concentrate the RF energy and cause tissue heating near the lead. Here, we present a novel design for a medical lead to reduce this heating by introducing pins. A pin can be taught as an electrical short that connects the main lead to the surrounding tissues. Initially, detail analysis of our proposed design is carried out by using Ansoft HFSS. Then, peak 10 g specific absorption rate (SAR) in heart tissue, an indicator of heating, was calculated and compared for both conventional design and our proposed design. Remcom XFdtd software was used to calculate the peak SAR distribution in a realistic model of the human body. The model contained a medical lead that was exposed to RF magnetic fields at 64 (1.5 T), 128 (3 T), and 300 MHz (7 T) using a model of a magnetic resonance birdcage body coil. We demonstrate that our proposed design of adding pins to the medical lead can significantly reduce the heating from different MRI systems.

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