Patent ID: 8710826

Claim:
A system, comprising: a stimulation lead having a proximal portion and a distal portion; at least one electrode along the distal portion of the at least one lead; and an implantable medical device, coupled to the proximal portion of the lead, the implantable device including: a stimulator adapted to generate stimulation signals with appropriate signal characteristics to provide therapy; and a controller to communicate with the stimulator, the controller being adapted to deliver an electrical signal to the at least one electrode to provide therapy; a sensing circuit including at least one inductor having a magnetic core that saturates in the presence of a magnetic field having a prescribed flux density of a magnetic resonance imaging device; and an impedance measuring circuit connected to the sensing circuit, the impedance measuring circuit adapted to periodically measure impedance of the sensing circuit and to provide a signal to the controller when the impedance changes by a prescribed amount.