Impedance measurements detect the temperature rise near DBS

Motivation: Scanning patients with neurostimulators is a serious safety concern. Goal(s): To work towards subject- and situation-specific risk assessments for implant carriers by demonstrating that crucial safety information can be read directly from a commercial deep brain stimulator (DBS) device. Approach: Calibration, phantom and MRI experiments based on impedance measurements of commercial 8-electrode DBS lead are performed. Results: RF-induced heating alters the tissue electrical conductivity (~2%/℃) around DBS electrodes, which can be measured as an impedance or reciprocal admittance change. The causal relationship is demonstrated at both 3T and 7T. RF-induced heating is suppressed using implant-friendly mode in MRI solely based on impedance measurements Impact: This work opens the door towards direct temperature measurements near the tip end of active medical implants using the implant itself as a temperature sensor. This could bring a disruptive change in the management of implant safety in MRI.