Last Thursday afternoon I made an unplanned visit to the ER with a ‘suspected stroke’. Because of my physical symptoms the ER Doctor ordered an MRI of my head. Of course it was necessary to remove my insulin pump and the Dexcom. The MRI was done with ‘contrast dye’ (I don’t know the name of the medication that was used). Later that evening I inserted a new sensor and everything seemed to be OK after the warm up period. During the night the Dexcom alerted me and the onscreen message indicated that “sensor failed”. Since I was a patient in the hospital and I had a room mate, I didn’t feel it was appropriate to try and wait out the re-starting of that sensor. I removed the sensor and put the transmitter in my purse and went back to sleep. I am wondering if the contrast dye that was used could be responsible for the sensor failure? I know certain medications like Tylenol are not good for the Dexcom, but I haven’t been able to sort out the possible reason for the sensor failure since it was brand new. I made the mistake of throwing the old sensor away, so I can’t call Dexcom regarding my problem. Sorry for the long post…
You should still call DexCom with the question. If they ask if you have the old sensor simply explain the situation to them. I’m sure they’ve had others lost as well. They should know about the failure though and will know if they have a record of other sensors failing shortly after MRI’s.
First of all, you could still contact DexCom customer service about the failed sensor. My experience with DexCom service indicates they do not play games looking for excuses to deny resonsibility for failed sensors. More than likely, your sensor failed during your sleep when you rolled over and either slept on it for a while or bumped it. In retrospect, I think I have killed some sensors placed on my right side because I tend to sleep on that side.
I recently underwent a cardiac stress test that uses similar radioactive dyes. I did not need to remove my sensor and the sensor was uneffected by the dye. Thallium, Gallium and some other radioactive markers are incorporated into chemicals that the body absorbs and uses in normal body chemical processes. From a chemical point of view these marked chemicals are no different from the non- radioactive versions that your body uses. Your body uses the radioactive marked chemicals in the same ways as it would the non-radioactive chemicals. The difference is that the radioactive markers give off protons which the camera/detector “sees.” The radiation passes through your body just like light passes through water. Modern imaging software then converts the information from the camera/detector to meaningful images which enable the doctors to view your brain tissues. The “cameras” are very sensitive and the amounts of radiation are very small. The process taking place in the CGM sensor is a chemical process unrelated to nuclear decay process.
I hope you are recovering from your episode and that this little explanation of mine eases your mind.
AaronM
Thank You Rebecca and AaronM - I did make that phone call to Dexcom this morning and spoke with a very nice young lady. She told me that to the best of her knowledge they didn’t have any complaints of sensor failure after an MRI…BUT that I did the right thing to remove it during said MRI. Then she offered to replace the failed sensor even after I explained my situation. I was very happy and surprised to hear her say that. Just wanted to let you both know I appreciate your advice. Thanks. 
I’m glad to hear this. I’ve never been anything less than impressed with DexCom customer service when a sensor gets messed up. Right now they really seem to be doing things right.
I am happy to have been of help. Hope you are feeling better.