Wednesday, December 03, 2008

MRIs and Cochlear Implants

Let's talk MRIs.

When I went to Chicago for the ALDA convention, I met several people that didn't want to get a cochlear implant because they need an MRI every six months. I will admit when I first started researching cochlear implants, MRIs was not a major concern of mine. I just read the I can have a MRI done if the magnet was removed. Fine. Great! That is all I needed to know but now I realize how much it means to others that suffer from other illnesses where they require MRIs.

Why would a person need to get one? MRIs provide better contrast in soft tissue, which helps to distinguish between normal and diseased tissue. MRIs do not show bones like a CAT scan or X-Ray. Brain tumors, strokes, multiple sclerosis and Neurofibromatosis, type 2 (NF2), are diagnosed by an MRI. Which means anything metal - paper clips, pens, keys, jewelry, scissors, underwire in your bra, belts, glasses and any other small objects can be pulled out of pockets and off the body or out of the body can become dangerous projectiles hurdling at the opening of the tube at incredibly high speeds.

Joy. Its a good thing that they make you remove anything metal.

Could you imagine if someone left a tongue piercing in and they turned the MRI machine on? Ouch.

Anyway, I did me a little research on MRIs. The magnet in an MRI system is rated using a unit of measure known as a Tesla and they are grouped into three fields.

Low-Field = Under .2 Tesla

Mid-Field = .2 to 0.6 Tesla

High-Field = 1.0 to 1.5 Tesla

What is the difference between low-field and high-field? The high-field setup has superior image quality AND has a higher rate of detecting tumor remnants. This abstract that I found supports that statement. The next generation of MRIs are circulating around at the strength of 3.0 Tesla.

Sounds like the higher the Tesla - the better the detection rate. I would imagine it would be like going from a two mega pixel camera to a ten mega pixel camera.

Now both Advanced Bionics, HiResolution Bionic Ear System's HiRes 90K implant and Cochlear Americas, Nucleus Freedom is MRI Safe up to 1.5 Tesla with the internal magnet removed.

I took a look at Med-El's website and discovered in bold letters, MRI Safe - Without Magnet Removal. Leaping lizards, no faking! They don't require the internal magnet to be removed. In fact, it is designed where the magnet can't be removed at all.

That cool!

But then I read the fine print:

In the US, PULSARCI100 and SONATATI100 are currently approved for use at a scanner strength of 0.2 Tesla.

Oh. That means recipients of a Med-El device can only use MRI's rated at low-field strength of 0.2 Tesla where they could be sacrificing image quality that could lead to a potential misdiagnoses.

What if one with a Med-EL device wants a high-field MRI that has a better image quality and higher rate of detection? Does that mean the entire implant has to be removed because they don't have a removable magnet?


This is a link to an article that talks about the latest MRI machines that are rated 3.0 Tesla which can demagnetize an implant. It also discusses how there is permanent damage to devices with non-removable magnets such as Med-El's PULSARCI100 and SONATATI100.

However, I'm privileged to know someone in my harem of cochlear implant users that had an MRI done and had the internal magnet removed and what he had to say really calmed my nerves if I ever had to get one.

First of all, it seems to be kind of a rare event. My surgeon has performed over 550 implant surgeries and has never had to do this procedure (taking the internal magnets out, then reinserting new magnets). In fact, of the 700+ Midwest Ear Institute patients, I believe I am the first to have an MRI. To get an MRI, the internal magnets need to be removed from the implant, then you get in the tube, then back to the OR to have new, sterile magnets and stitched up. The thought of having the internal magnets taken out probably bothers some people but it shouldn't - it was not a big deal at all. In fact, they asked if I wanted to be sedated and I said no - so they just did a local and it was fine. There is a little pain...but very little, and easily handled with OTC pain relievers. In fact, I haven't needed any today at all. I was going to write a great, detailed account of this but it is such a non-event that there is little to write. Kind of like getting some stitches in your head - that's it. The most irritating thing is being inside the MRI tube - at least you can't hear it though, because you are completely deaf while inside.

I wouldn't go get an MRI for fun, but if it is suggested that you need one, please do not hesitate to do it. An MRI is an incredible piece of technology and can be a difference maker in terms of diagnosing certain things.

And that is all he said folks!


mishkazena said...

That's correct. The magnets of newer cochlear implants are designed to be removed easier.

What about the older models? Are the magnets more difficult to be removed?

Sam said...

Interesting and thoroughly researched article! Thanks for the insight! :)

Vivie said...

Pretty good article Abbie...

Can I translate it for my Greek blog ? I'll give you full credit , it's just insightful.

Anonymous said...

WOW! Thank you for this article! Can I get your permission to post your post on my blog? said...

i love my cochlear implant too much to even dare get a MRI! I wouldnt like to lose it but if something came to the crunch and i needed an MRI scan for a serious disease or condition i wouldnt hesitate but for now im staying well away from them! haha

Anonymous said...

That's interesting post you provide! Good work, girl.

It made me to think about other metal/screw surgeries in other parts of the body.

MRI can do anything!

Doctors, researchers and others require to study calculus/physics to success anything!

What's next? Airport's Security Scanners.....they ought to fix anything.....

White Ghost

MKChaikof said...

Check out , MRI Machines May Damage Cochlear Implants, which talks about state of the art MRI equipment that operates at 3 tesla. The article states that CIs without removable magnets were tested on these machines, and they are not safe. Since CIs are expected to be in place in a person's head for 20+ years, I think that the removable magnet is the better way to go since we can't anticipate future MRI technology.

Anonymous said...

A friend of mine is Deaf, his brother hearing mentioned that he has to have xray first before MRI. The reason, he works in the metal shop, he may have the metal dust in his eyes. Doctor prefer to have xray on his head before process to MRI to see any white spots on the Xray films. Otherwise, MRI will picking up the metal dust might damage his eyes.

Anonymous said...


Great informative article! I've always wondered about MRI and its effect on the cochlear implants.


Laurie said...

What a great and informative article, especially the "fine print" about Med-El and MRI's.

As you know, I am dealing with some health issues and the easiest way for my ENT doctor to make a quick diagnosis would be to do an MRI. He is also my CI doctor and knows he cannot do that. So, he is doing two other tests instead to confirm his diagnosis, which I will post in my blog when I find out (probably in January.)

Hugs to you! I miss you!

Abbie said...


The older models such as the AB's Clarion I and II does not have removable magnets. Cochlear Americas, Nucleus 24 implant is rated as MRI safe up to 1.5 Tesla. There are two models for Nucleus 22 implant that does and does not have a removable magnet.


Go right ahead and translate it and thank you for spreading the word!


Please go right ahead!


Thank you for that link! I've updated the post to point that out. I just read that article last week too!

Laurie hon,

I am really praying for you! I miss you so much :(

David said...

Well researched and well written. Thanks Abbie.
Much needed for many!

Mistabone said...

One of the most interesting articles with real concerns about CIs. I am a CI user as well and my ENT always advised me about the importance of removing the magnet. I wonder about those that often need it in the lomg term - will constant removal eventually lead to scarring, perhaps a possible change in CI performance from constant soft tissue manipulation?

Vivie said...

Hey Abbie..I did a loose translate of your article ( yeah late I know , but been busy ) and I want to thank you for your terrific help again!

look it there , and in the bottom I'm thanking you in English!

I look forward to any other useful articles you publish!!

Vivie said...

Abbie just wanted to get hold of you...Seems that MEDEL are approved in Europe without magnet removal for a MRI 1,5T without magnet removal.

I'm not sure though if that *is* true , haven't seen any official word on it.

assyntca said...


Moreover, even the web sites of Cochlear Corp. claim their Freedom implants to be safe for MRI scans up to 1.5 Tesla without the need to remove the magnet, and up to 3 Tesla with the magnet temporarily removed. You can find this statement on every Cochlear site across the globe except the North America version (I checked UK, AU, DE, SP, and South American sites). I just cannot help wondering why the information for US and Canada stands out...