MRI: Myths and truth

Recently, I came across a query from one the patients, “Is it safe to breast-feed after MRI? If no, then how long we should stop?” For the moment, question seemed weird to me, and tried to analyze magnetic susceptibilities of breast milk in my mind, but I was going nowhere. Being a radiologist, never heard of any such contra-indication. But yes, if at all, contrast is to be administered, there is a catch! So, I thought of clearing such myths which exist in our mind, when we go for MRI.

Myth 1: MRI gives a lot of radiation, and may cause undue illness.

Truth: MRI has nothing to do with radiation of any kind. I think we are confusing it with CT scan. It’s the CT scan which is a similar kind of machine and procedure, where we use radiation. MRI can never ever give a radiation, or cause any undue illness just due to the procedure. Sometimes, we do need to give a contrast injection, but it will be pre-informed, and will only be given after assessing renal status. In patients with renal failure of certain degree, contrast can cause reactions and undue illness. But, a non-contrast MRI, which is done more commonly, causes no harm of any kind to anybody.

Myth 2: Breast feeding after MRI is to be avoided for 24 hours.

Truth: There is absolutely nothing like that, and MRI is perfectly safe for breastfeeding mother as well as baby. It has no after-affects. In some cases, when we need to give contrast, then mother should express the breast milk before the study, and keep it for use during next 24 hours. Contrast may be secreted in breast milk. However, contrast won’t be needed in most cases to make the diagnosis. E.g. if you have back pain and need to find out if there is disc prolapse, there is no need of contrast. Even if contrast is needed, patient will be informed in advance, and they can prepare accordingly.

Myth 3: Oh! That black-hole machine, they will leave you in narrow hole in a dark room with nobody around and a lot of noise.

Truth: I do see people sweating before going for MRI and even during the procedure still, but it’s much rare these days. It’s more of pre-feeded notions, which bring fear. It’s usually a well-lit room these days, and the machines are getting wide-bored and sometimes, open MRI machines, where there is no hole at all. But, a machine with a hole has better resolution and gives good images. Technologist team can always see you, through the glass, and you can see him too. A buzzer will be given in your hand, which you can use in any emergency to call the technologist, and immediately stop the examination. Also, any of your friend or relative can sit with you through out the examination. A nice music would be played during the examination, and ear plug will be given to avoid the machine noise. Definitely, its not a fun-game, rather a diagnostic test, which you need urgently to figure out your disease, but there is nothing scary or eerie feeling about it. It can be the most pleasant test you will have.

Myth 4: I cannot have MRI, as I have a metal rod in my leg.

Truth: Almost all the metallic prosthesis or implants these days are MR safe.

However, these implants should not be there –

1. Pacemaker (however, MR safe pacemakers have also come now)

2. External hearing devices (should be taken out outside MRI room before the procedure)

3. Foley’s urinary catheter (especially one with temperature sensor to be avoided. Better to take it out before the procedure. However, there are ways to make it MR safe. http://www.mrisafety.com/safety_article.asp?subject=206 )

4. Penile implants (however, MR safe penile implants are available)

5. Pellets or bullets inside body or spine (better to avoid MRI if possible)

6. Transdermal patches (better to take it out before the procedure, and may be re-implanted, especially if they contain some metallic component like alumunium)

7. Cochlear implants

Which implants are safe:

1. Metal implants in hand, leg, shoulder etc. (Unless it was implanted some 20 yrs back!, when we had magnetic implants)

2. Intrauterine contraceptive devices including MIRENA

3. Artificial lens in eye

4. Denture

5. Screws and plates in spine

6. Prosthetic heart valves (they are mostly safe, but, indication of MRI should be justified)

7. Knee or hip replacement implants

8. I.V. cannula, central line or chemotherapy ports

09. Surgical sutures, especially if done 3 months back.

10. DJ stent

11. Guidewire

Please pre-inform the technician if you have these implants

However, all the information about any implant, will be asked before examination. But, please inform the technologist about these implants, so that he can take certain precautions during study

1. Permanent tattoos in body – sometimes, people may experience some itching or burning sensation, which should be pre-explained to the patient and patient should also inform immediately during the examination.

2. Body piercing jewellery – ideally, they should be removed before the examination. If not possible, then, they should be taped or glued to some fixed part o