electrode 1730 to isolate the electrode 1730 an example of the magnetically sensitive switch may be found in u s application no 61 981 768 which is incorporated herein by reference returning to the imd 1702 the probe processing unit 1722 may be a conventional temperature sensing unit but in this case has an electrical connection suitable for receiving the electrical signals produced by the temperature sensor 1738 the probe processing unit 1722 may have an output that is electrically coupled to the stimulation engine 1708 and or to a controller 1710 of the imd 1702 the probe processing unit 1722 may then output a signal representative of the measured temperature to the controller 1710 and the controller 1710 may then compare the temperature to a threshold and take further action such as causing the stimulation engine 1708 or other circuit to shunt any energy to the device case or other heat sink or to telemeter an alarm or machine instruction to an external device to cause the mri scan to be altered alternatively the probe processing unit 1722 may perform additional logic such as comparing the temperature to a threshold and then sending an interrupt signal to the stimulation engine 1722 or other circuit to cause further action to be taken such as operating a switch to shunt the energy away fig1 shows a set of operations that may be performed by a controller of an imd as introduced for the various embodiments above where a temperature sensor with a fiber optic signal path or a dedicated electrical path is being used in this example the controller receives an mri trigger at an operation 1802 such as receiving a telemetry signal that instructs.