[00:18] Hello. My name is James Whittaker and I’d like to ask you to remove all the ferrous objects from about your person before I welcome you to the third episode of ‘Conditional 1’ my occasional podcast focusing on all aspects of MRI Safety.
[00:34] In this episode I’ll be continuing my discussion of the MRI safety checklist that every patient has to complete before their examination. In Part 1 I touched on where and how to ask these questions and I’ll begin Part 2 with a little sidestep down a path less travelled…who should we be asking these questions?
[00:54] What do you do if the patient can’t answer your questions? It’s almost inevitable as an MRI tech that you’ll encounter patients who don’t speak your language and every workplace will have its own way of handling these patients. I’ve encountered everything from having hospital employed translators available for just about every language you could imagine all the way down to speaking into a patient’s phone in the hopes that google translate knows what a neurostimulator is. A common scenario in New Zealand is having a non-English speaking patient accompanied by an English-speaking family member, often a child or younger relative who has been born and raised in this country. Dependent on local policy, using this family member to translate can be a huge help or a total no-no. I’m not here to tell you how you should approach this, but as always you need to be confident of the accuracy of the information you are receiving.
[01:51] What do you do if the patient isn’t able to communicate for another reason? A few years ago I was in just such a situation. I was asked to scan a lady who had suffered a brain haemorrhage. She was awake and alert but completely non-verbal. I remember her husband was supporting her and he was answering the questions on her behalf as next-of-kin. No pacemaker or other heart surgery. No brain surgery but she had had some surgery on her left knee, possibly a cruciate repair. Nothing appeared amiss so we transferred her into the scanner and got underway.
[02:28] I still remember the first localisers coming up on the screen and getting a sudden queasy feeling in my stomach as I saw the signal void in the centre of her head. I remember talking to the patient via intercom and asking her if she was ok. I can’t tell you how relieved I was when she gave me a thumbs up. I told there would be a short pause while I set up the first scan and to keep her head absolutely, perfectly still. I reviewed her CT from the previous day and there larger than life was an aneurysm clip that as it turns out had been placed after her first brain haemorrhage.
[03:06] As she was not in any distress, for the time being at least, I decided that the safest thing to do was not to move her until I knew what I was dealing with. I remember going to talk to the patients’ husband and asking him about the clip that he had told me wasn’t there. Did he remember when it was placed? Where was the surgery performed?
[03:25] I can’t tell you how relieved I was when he told me it had been placed at a local neurosurgical centre just a couple of years before and I could quickly confirm that it was an MR conditional clip and that I could safely continue with her scan. It all went very smoothly, we returned her to the ward and then I took a short break and seriously considered throwing up. Looking back, I’m still not sure what I would have done if it transpired the clip was MR unsafe. Would we have had to quench the magnet? Would we have been able to slowly withdraw her from the field? I’ve thought about that a lot over the years.
[04:04] In the debriefing afterwards I was very surprised to find that in New Zealand next of kin don’t automatically have power-of-attorney and ever since I’ve been sure to ask whoever is answering on behalf of the patient if they have the legal right to do so. Every state or country has different rules around this so please, please make sure you know exactly where you would stand should you find yourself in a similar position.
[04:31] Now, for those who have heard me talk about this at Conferences or study days you’ll know that this next question is my favourite. I don’t ask “Were you welding yesterday?” or “Have you got metal in your eyes in the last week?” No. “Have you EVER had any injuries or accidents where metal objects may have entered your eyes?” to which the answer is often “Yes, but that was years ago.” It doesn’t matter…and I explain it to the patient as follows.
[05:00] “If you get a metal fragment anywhere else in your body it forms scar tissue as it heals, and this scar tissue can help to hold the fragment in place, though that’s not to say we don’t need to know about them. Unfortunately, your eyes are basically little balls of jelly and there’s nothing to form that scar tissue or hold the fragment in place. The magnet in our scanner loves metal and if you go in the room our scanner will find any bits in your eyes, no matter how small and move them. At the very least it’ll hurt like blazes and worst case it can blind you.”
[05:33] In addition to eye injuries, we need to know about any surgeries to the eyes. There are a huge array of surgical implants that ophthalmologists place nowadays, from glaucoma drainage devices to scleral buckles, to gold or platinum eyelid weights for patients with Bell’s palsy or other types of facial paralysis.
[05:51] Now, how you clear your patient for scanning will again vary from centre to centre so I won’t delve too much into specifics at this point, though it would be cool to do an episode on this in the future. I will say this, however. No matter how busy you are, or how frustrating it might be to have to take the time to get your patient’s orbits imaged no one will thank you for cutting corners. I’ve seen the aftermath of an MRI related orbital injury and it’s horrific.
[06:21] While I’m asking about metal in the eyes, I always follow up more generally to ask about bullet wounds or shrapnel that the patient may have inside them. Fortunately, here in New Zealand the answer is rarely yes, but as there is a thriving rural hunting community and accidents sadly happen, we occasionally find pellets or bullet fragments in strange places. Relatively little of the ammunition in non-military use is ferromagnetic but unless you know exactly what you are dealing with, always assume it’s ferrous. It’s not a hard contraindication, but case by case analysis is required. How long has it been there, is it near any vital organs? What body part is being scanned and why? These are all discussions to have with your Radiologist and the referrer before a final decision is made.
[07:10] I think it would be extremely difficult, if not outright impossible to explicitly ask patients if they have every type of conditional or unsafe implant so there are some more general questions that I would ask as part of my spiel.
[07:24] “Have you ever had any other surgeries (or procedures)? Have you ever had any metal objects placed inside your body, such as broken bones with pins or plates, joint replacements, stents, clips, tubes or anything inside your body that you weren’t born with?” I used to ask if patients had anything man-made inside them, but one patient very shrewdly answered that technically everything inside him was man-made, and I couldn’t really argue with him about that.
[07:56] One of the more intrusive questions we have to ask as part of our spiel is the pregnancy question and it’s amazing the range of answers we get, I’m sure you’ll agree. From the vaguely offended denial to the total oversharing of fertility information we get it all. I’m occasionally asked why I need to know, and it’s a reasonable question considering I’ve just spent the last 5 minutes telling the patient how safe MRI is meant to be. I usually approach answering something like this:
[08:26] “MRI is still a relatively new technology and while there haven’t been any studies that suggest that it can harm your foetus. Doctors are usually very conservative and don’t want to take any chances with the health of patients under their care. So if you are pregnant it might change what we do, or possibly when we do it.”
[08:46] For a long time it was considered to be contraindicated to perform MRI during the first trimester of pregnancy, which I believe was due to it being the time of most rapid development of the unborn child and thus the period of greatest theoretical risk. That has changed now though and MRI can be performed at any stage of pregnancy, assuming there is a real need for it. Research has found no evidence to suggest that scanning at 1.5T causes any adverse effects for mother or foetus. During the first trimester MRI is usually performed due to health issues on the part of the mother rather than the foetus and so is often preferable to x-rays or CT which have a known and quantifiable ionising radiation risk.
[09:32] A small but growing percentage of our female patients will attend with intra-uterine devices or IUDs in place and some are understandably concerned about how it may be affected by exposure to the magnetic field. As of 2018 2% of American and 6% of European women had an IUD in situ and the vast majority of these western IUDs are copper, gold or plastic and thus can be considered MR conditional. Bussmann et al. in 2018 found that there is very limited heating, attraction or artefact relating to these devices at fields of up to 3T.
[10:11] In Asia, specifically China the situation is entirely different. As of 2018, it was estimated that 44% of Chinese women between 15 and 45 had an IUD in situ. There is some discussion as to exactly why this is, but one suggestion is that the one-child policy of the Chinese government between 1979 and 2015 was a significant contributory factor.
[10:38] An interesting statistic perhaps, but why do we care about that in the setting of MRI safety? Well, during the 1980s 90% of IUDs placed in China were made from stainless steel, and unlike their western counterparts the Chinese ring is subject to significant attraction and torque when exposed to the stationary field gradient. These Chinese ring IUDs have a much longer life span than western IUDs and could easily stay in place without issue for up to 20 years. These ring IUDs stopped being manufactured in 2000 but may still be found in older Chinese ladies who may no longer need them but have never had them removed. In my practice in New Zealand I have encountered these Chinese ring IUDs more than once, so they are definitely something to be aware of when scanning female Asian patients.
[11:32] Another question that many patients take issue with is the matter of weight. Many patients either don’t know their weight, are in denial about their weight, or are defensive about their weight. Now, while I suspect many of us have made use of the ‘Best Guess’ methodology in the past, to avoid over heating our patients we need accurate measurements. I’m fortunate in that the scanner I currently work with requires height and weight for its Specific Absorption rate calculations so I do confess to drawing patients’ attention to the measuring tape on our wall, that just so happens to have some scales next to it.
[12:09] I’ve also become a lot less trusting over the past couple of years when it comes to believing what I’m told by referrers about patient weights. As I know you’re all aware, there is a large and growing population of large and growing patients out there and the number of conversations I’ve had regarding table limits and bore size has increased exponentially. My usual conversation with the referrer goes as follows.
[12:35] “Hello MRI, I’ve got a patient here that needs a scan urgently. What is the weight limit for your scanner?”
[12:42] “Why, how much does your patient weigh?”
[12:45] “I haven’t weighed them yet – what’s the maximum that your scanner will take?”
[12:48] “Find out how much they weigh, and what their circumference is at their widest point and I’ll let you know if I think they’ll fit or not.” At this point the Doctor will try a couple more times to find out what the scanner limit is. Stand firm, or more than likely they’ll find out that their patient weighs 5 kilos less than the scanner maximum when they’re on the ward, but that they’ll magically gain 10 kilos when they arrive in Radiology. Same with circumference.
[13:15] Now, talking about this scenario has just triggered a thought so I’m going to go off on a brief tangent for a moment. When it comes to non-MRI staff coming in, who should be getting safety checked? The short answer is Everyone. The long answer is everyone (said really slowly). Your workplace should have a separate safety form for staff. If it doesn’t, I would strongly recommend making one. Whenever a new staff member wants to enter Zone 3 a member of MRI staff should go through the form with them, ensure everything is ship-shape and then the form should be retained, electronically if possible but definitely in a format where it can be searched for and found easily. These forms should be reviewed regularly and updated as necessary. There we go, end of tangent and back to the patients.
[14:10] Towards the end of my spiel I move away from what the patients have in them, to what they have on them. Tattoos have a small risk of interacting with the radiofrequency field to cause skin burns so it’s important to know what tattoos a patient has, where they are, as well as how long they’ve been there.
[14:29] There are a number of case studies in the literature about patients with tattoos or permanent cosmetics complaining of erythema or redness, or suffering burns around their tattooed skin. A 2002 study by Tope & Shellock found that 1.5% of patients with tattoos reported an adverse event in MRI, but 6% of patients had been refused an MRI due to their body art. Ferrous compounds can be found in red, pink, brown, black and yellow pigments and some blue pigments can contain cobalt. In New Zealand there are NO regulations around who can tattoo or what can be in the ink used, so a certain degree of professional paranoia is definitely in order. I’d be interested to hear what the local rules in your region are, so please get in touch and let me know.
[15:24] I’ve only ever had one patient complain about warmth or sensation in their tattoo and it was a gentleman who had been inked by a friend while incarcerated. I can only imagine that the black pigment had some ferrous component, though he had no idea exactly what had been used. A cold compress on the tattoo acted as a heat sink though and we were able to complete the scan without further issue.
[15:49] Body piercings are a bone of contention for many MRI Techs but my feeling is definitely that if a piercing can be removed without damaging the patient it should be. Any that can’t be easily removed should be carefully tested with a hand magnet for any magnetic properties. It’s interesting how many patients say that they can’t remove their piercings but change their minds when I put on my surgical gloves and bring out the pliers. If patients are worried about their piercings closing over then non-metallic spacers can be put in for short periods by any piercing shop. Despite having no tattoos or piercings myself I am on first name terms with the staff at the nearest piercing shop, and dependent on where your practice is based, I would suggest reaching out if at all possible.
[16:36] Last, but by no means least I ask my patients about false teeth and hearing aids. I do it last because many patients when told that they need to remove their hearing aids will do so immediately, with obvious impacts on the quality of communication afterwards. Also, if they don’t take their hearing aids out, they can sometimes forget about them, and many are so small now that spotting them before the patient is trying to put their earplugs in is problematic.
[17:05] It’s also fascinating to me how many patients don’t know if there is any metallic component to their false teeth and will then take them out to show me, which is especially off-putting just before or after lunch. [17:18] On a more serious note, as I was researching this episode I became aware of a recent tragic case in Arkansas, in the United States. 14 year old CJ Harris suffered a significant head injury in a quad bike or ATV accident in March of this year, suffering a brain haemorrhage and fractured skull. In the days before his death at the end of March, CJs parents asked for an MRI to be performed which was allegedly initially refused due to CJ having orthodontic braces. There is an ongoing lawsuit surrounding the circumstances of CJs death so we may never know the full story but it does appear that there was a delay in the scan being performed due to concern that artefact from the braces might render the MRI non-diagnostic. It doesn’t appear to be strictly an MRI safety issue except for the discussion around whether MRI was an appropriate examination for this young patient to undergo. I think we can all agree that it’s a sad case.
[18:20] One thing that I would strongly suggest when safety checking your patients is going through the full consent process for administration of contrast media. Unless you are absolutely certain that your patient won’t be injected with contrast I feel it’s better to at least discuss it with them. Otherwise, if you have to give contrast due to an unexpected finding, you’re then trying to explain what it is, why you need it, and why you didn’t mention it before to a patient wearing hearing protection that you desperately don’t want to move. As with many other topics that I’ve touched on in the last two episodes, contrast agents in MRI deserve to be looked at more closely and I hope to do so in the not-too-distant future.
[19:05] When I reach the end of my safety checks I always finish with this. “Now, I’ve asked you a lot of questions but now it’s your turn. Has everything I’ve said made sense? Have I explained everything ok? What questions would you like to ask me?” The phrasing of this is very important because it takes the responsibility of understanding the process off the patient and on to me. Have you ever asked someone if they understand, and they nod and agree but you know for a fact they don’t really understand? It’s because no one wants to look foolish or stupid in front of others. By asking if I’ve made sense the implication is that they don’t understand because I haven’t explained well enough. It’s my issue, not theirs.
[19:45] By asking what questions they have, rather than “do you have any questions?” it gives them permission to clarify that one thing that bugs them or revisit the information that they didn’t quite comprehend. It gives the impression that questions are not just tolerated but expected and I’ve found that many patients will take the opportunity and be grateful for it.
[20:19] I’d love to get some feedback on this next part…how much clothing do you make patients take off for their scan? And what do you give them to wear in its place? I personally prefer to get all my patients to undress down to their underwear and ask my female patients to remove their bra unless it has NO underwiring or clip fasteners at back or shoulders. Also be prepared for the inevitable few who have neglected to put on underwear. My current practice has disposable underwear if required, but long cotton gowns or scrubs cover a multitude of sins. Hair clips, slides and bands should be removed. Jewelry off, with the exception of rings where arthritis or weight gain make removal unfeasible.
[21:05] I’m sure that many of you are all too well aware of the dangers of antimicrobial sportswear, but for those of you listening who haven’t had the pleasure as yet, these smart garments are advertised as performance or activity wear and have small metal fibres, usually silver woven into the material. These fibres can heat when exposed to Radiofrequency and back in 2012 an 11 year old girl sustained second degree burns on her abdomen after being scanned with a silver impregnated undershirt. Her case was unfortunately made more serious by the fact that she had been sedated for her MRI scan and it was only when she was roused that the burns were discovered.
[21:49] Moving on, another point I’d like some feedback on is this. Does your MRI suite have a shower? If it doesn’t it’s something that you might want to think about for the future. Why is that I hear you ask. Well, on the west coast of New Zealand, just outside Auckland is a place called Piha Beach. It’s an awesome place and home to some of the best waves in the country, as well as beautiful and amazingly ferrous black sand. From experience it can cause significant artefact on MR images and I can’t imagine it has a positive effect on field homogeneity if it collects in the bore.
[22:28] Ah well, I hear you say, that sounds like a very specifically New Zealand problem so why should I be concerned? For one thing there are black sand beaches all over the world, and for another it’s not just sand that you might need to wash off.
[22:44] A very good friend and colleague had to basically frogmarch a patient to the shower as he had just come from his job as a mechanic. He was insistent that he always wore eye protection when welding but unfortunately his goggles didn’t cover his head and he had slag, swarf and who-knows-what other fragments in his dreadlocks. Dreadlocks apparently only get washed once a week or so, so can you imagine how much metal was in there after a busy week in a workshop or garage?
[23:13] So, there you have it. I hope that all this has been helpful, or at the very least interesting. I appreciate that this has been a far from exhaustive run through, so if you have any safety checking stories of your own, I’d love to hear them.
[23:29] I’d like to say thank you to Purpleplanet.com for the use of their music, and also thank Jaenelle Whittaker for graphic design. If you have any questions about the content of this podcast, or ideas for future episodes of Conditional 1, please email me. My email address is podcast @ conditional1.com. You can also message me on my website www.conditional1.com.
[23:55] And remember, if anyone ever tells you that being an MRI Technologist isn’t Rocket Science, tell them No, but it is Nuclear Physics.