That is absolutly not true. The Magnetic field will adversely effect an electronic pump, causing inacuracy, false alarms or the pump to stop completely.
Medex is approved for use in the MRI.
Do you want to risk your patients life by using an pump off lable?
Of course, when you do that, you have to load the pump outside the scanner, as you have to remove them from the caddy to do so, and if you are in the room, they can be pulled into the bore. That slows flow through time.
It may be fine for sedation started in the room, but if the patient comes to MRI on a Heparin drip, how do you get the bag of heparin and tubing into the MEDEX syringe pump?
By risking infection by drawing up heparin out of the bag into a syringe, disconnecting the original infusion and connecting the one from the syringe pump.