Every time I've gotten an MRI the doctors and techs have sworn up and down it's impossible for this stuff to stick around. Getting tired of not being able to believe what doctors say...
You're making me feel lucky about what was otherwise a very unpleasant experience!
Pretty much just diluting it out of your system.
So this reveals to me two issues
1. In general side effects of the contrast agent are not communicated properly. If I knew, I might have asked - hey can you do the analysis without the agent?
2. There’s no recommendation to avoid vitamin C prior and right after the MRI, heightening the risk.
A chemist gave a great talk about this at a big MRI conference (ISMRM) in Paris 10ish years ago. His explanation was that gad behaves a lot like iron does in the body. It deposits where iron does and like iron it lacks a metabolic route for removal (though menstruating females lose iron).
He stated that deposition was entirely predictable. However the harm caused is still debated.
The article here says ‘ Dr Wagner theorized that nanoparticle formation could trigger a disproportionate immune response, with affected cells sending distress signals that intensify the body’s reaction.’
Emphasis on ‘theorised’.
Deposition is discussed in the below link, and the comparison with iron is briefly mentioned.
I hold a different opinion to you though, I'm glad doctors are always learning more while generally operating with good /extremely good intentions.
I agree. Expecting perfection from humans, even experts, is not reasonable and is frankly counterproductive.
Willful ignorance is one thing, but people who genuinely attempt to do the right thing at worst just need to be steered slightly differently.
There's a big difference between perfection and "Statistical Literacy Among Doctors Now Lower Than Chance"[1]. I don't think their intentions are bad, but they are woefully incompetent at many basic things.
[1] https://slatestarcodex.com/2013/12/17/statistical-literacy-a...
As it happens, the daily practice of medicine does not require interpretation of p-values. Indeed, medicine existed before the p-value.
The people who create studies that ultimately guide policy decisions are specialized (much like people who write GPU drivers are different from those who run inference)
What are you talking about? Doctors refer people based on test results every single day. From what I've seen, hardly any of them understand the precision/recall of the tests that they then use to refer you (or not) to screening procedures (which are not all harmless).
What are you talking about? How is a single lab value going to generate a p-value? Why are you presuming that your family med doc should be calculating an ROC for each of her 1,500 patients?
The selection of lab critical values is performed by experts in clinical pathology. Exactly the people who were not included in the paper you cited.
You can find links to support any argument you want on the internet.
To place this in clearer HN terms, you're saying that a front end dev is trash because he didn't write his own web browser in assembly.
Explaining to a parent the fact that their child did in fact not have a rare, deadly and incurable multi-system disorder even though an antibody which is 98% specific for it showed up on the antibody assay, that we took for an entirely different reason, is the kind of thing thats hard to explain without understanding it yourself.
If you use the centor criteria before resting for strep, is that worse than getting out a piece of paper and researching background population prevalence?
The OP is being dogmatic about doctors needing to know things he does which is obviously silly.
Edit - but yes, I agree that we should think about sensitivity and specificity, I just don’t think you need to be a statistician, just to have a helpful script and resources for patients who wish to know more.
A year ago, one insisted vehemently—to the point of yelling—that I shouldn't be supplementing Vitamin K because my potassium levels were fine.
https://en.wikipedia.org/wiki/Not_even_wrong
> "What you said was so confused that one could not tell whether it was nonsense or not."
OTOH Vitamin K can cause blood clots.* I assume you know this and are being appropriately attentive to the issue.
* The K comes from Koagulationsvitamin which it was called in Danish when first discovered.
This paper isn’t saying that MRI contrast agent is high risk in general.
There’s a risk in misinterpreting these niche papers to overstate their relative risk. This is a common mistake when people start reading medical papers and begin overweighting the things they’ve read about as the most significant risks.
But yes cts are cheaper.
There's risk in life and odds-wise if you're in the developed West, you're going to get care and medicine that will greatly prolong your life.
Also this paper is super vague. What percent of people even get this? How long does it last? They havent even done a study to see how long it lasts yet. I have a feeling this isnt going to be our generation's asbestos or thalidomide.
That being said, you should decide your own risk profile. If MRI gives you concerns there are alternatives that dont involve contrast.
But given our track record, a little humility would go along way.
When a highly educated doctor tells you that something is safe, a person is going to assume that means that someone somewhere has proven that the substance is safe. If what they really mean is that no one really knows, but so far, no experiments have been able to prove danger, then we should say that instead.
You can’t prove a negative.
But when a person who doesn’t spend their time nerding out on science goes to the doctor and hears, “the substance is safe”, it is not a guarantee that they know that you can’t prove a negative. If you can’t be sure that your audience knows that it’s not possible to prove a negative, then you should be pretty cautious with your words.
Tylenol is safe. Tylenol can also permanently damage your kidneys.
Walking is safe. Walking can also permanently damage your cartilage.
Food is safe. Thousands of people die from choking.
We all know this, colloquially. When it comes to medicine, it is as if one's brain hops and skips right out of their ear. It's not magic, it works like everything else on Earth works.
These people are then dishonest, because they know, deep down in their heart of hearts, this is absolutely not what safe means.
Again, everyone agrees eating an apple is safe. It's even good for you! But they also know every time they take a bite, there is a risk that they can choke and die. They know that. I know that. You know that. Everybody knows that.
Colloquially, even to the most naive, we know that zero risk does not exist, and that "safe" merely means "an acceptably small amount of risk". If we are changing our definitions based on the context, for example, everything on Earth and then medicine, that is dishonesty. If we are dishonest to ourselves, then we are delusional.
Contrast agent has been widely studied and determined to be reasonably safe. You’re not going to be administered any routine procedures or compounds that are known to be dangerous without an examination of the risks and benefits.
> If what they really mean is that no one really knows, but so far, no experiments have been able to prove danger, then we should say that instead.
“No experiments have been able to prove danger” is too generic to be usefully different than saying that it’s understood to be reasonably safe.
Even this paper isn’t saying that contrast agent is bad or dangerous in general. It’s exploring a potential effect that we can now detect and study.
Every procedure has some negligible risk, and doctors are trained to mitigate major risks to peoples' health with screenings, medications and surgeries that are of lesser risk than the alternative of inaction. "Safe" is a reasonable explanation for the vast majority of laymen they have to communicate with.
We shouldn't have to clarify that everything is only 99.999% safe and assume that everything carries some form of risk even if small.
Going for a test itself via car has a quite significant risk itself, should the doctor say that you shouldn't move out of this room, it's not safe?
Like even regularly used medicine has some slight chance of an adverse reaction, that's how minuscule side effects multiplied to human population times the number it's taken results in.
Guess what often has many orders of magnitude greater risk? Continuing having the disease you went to the doctor with in the first place, or having it lie undiscovered.
Which is strong evidence that the danger is very small, very rare, or takes a very long time to develop.
You don't need a large clinical trial to prove that being shot in the head is harmful; you do need a very large trial to detect that, say, a drug increases the risk of cardiovascular disease by 4% in a specific sub-population.
Here in Germany you have to sign something if they give you "stuff" informing you of possible risks. Something that always exists.
That's why we don't give MRI's out the wazoo. We actually gatekeep them a lot, and most research will tell you that investigative MRIs without chief complaints are a bad idea and we don't do them.
I had cancer. I had no MRIs, but multiple CT and PET scans. CT scans and PET scans have risk - they don't just do those for kicks. But you know what else has risks? Cancer. So there's a calculus here.
Every single medical procedure, down to getting your blood drawn, has this calculus. Nothing is risk free.
Why? What are the risks of MRIs without contrast?
These types of MRIs often cause anxiety and can lead to riskier medical procedures that are not necessary. This is because imaging is actually not perfect. There is always a risk you see something there that is not a big deal, or that you misinterpret the image. That potentially means unnecessary surgery or medicine. That can kill you.
That's why if you go to any doctor in the US and say "I want an MRI, no, nothing is currently wrong with me" they won't do it.
In medicine, there is obviously a benefit in having less data. If I told you that you have a vein in your brain that could aneurysm at any point and instantly kill you, but no, we can't do anything about that - would that help you?
No, that would exclusively make your life worse, at least for the vast majority of people. It's also true for a lot of people. It could be true for you, right now.
Also, just because the error is in interpreting DOES NOT mean that the MRI is somehow magically off the hook. The risk came from the MRI. If you never did the MRI, then it would be impossible for that scenario to happen. That's just plainly true.
So therefore, if you do the MRI, there is a risk of that happening. Taking that risk without any complaints is deemed not worth it, so we don't do it.
There is no 'perfect information' but instead there is noise with every signal. It feels like that shouldn't be true ('the picture shows exactly what is happening, right?') but there are several levels at which the 'truth' that is assessed in an MRI can be degraded that have nothing to do with misinterpretation.
Even 'misinterpretation' is tricky - if something is only sometimes going to cause a clinically bad outcome, commenting or not commenting isn't a question of interpretation but of personal practice standards.
As a thought experiment, if MRI was as cheap and fast as testing blood pressure, do you think they’d still be given as rarely?
You’re assuming that we would skip this step, implicitly.
Now when would we do further screening? In a Bayesian framework, when we have a certain pre-test probability that we think we can improve to our desired level of post-test probability in order to take an action.
The fact that this is all automated doesn’t change our uncertainty about whether borderline calls should be targeted. Indeed, we’ll likely have more stringent criteria about things to ignore than are used today, and that may be worse for the small number of times we currently catch an actionable incidental finding.
And we’re not even beginning to consider cost, resource misuse, and the risks we’re incurring (an MRI machine isn’t safe to be around and costs a lot to maintain)
Edit: the things that kill people are smoking, heart disease, lack of exercise and poor diet. Targeting these is so much more useful than detecting a larger number of incidental findings
https://www.linkedin.com/posts/gunnmartin_ranzcr-activity-72...
They’re also loud and can give patients a sense of claustrophobia or panic.
However, I do think the reason MRI aren't used more often is because they are fucking expensive to operate. They need to run more or less 24/7 to be economical, which means they are commonly not scheduled with slack for "optional" investigations.
I've only had a couple with contrast. My understanding is that contrast highlights abnormal stuff and some tissue sorts more than without contrast. Specifically, they use it in MS to get a better look at an active lesion in the brain. You can still see the lesion without the contrast, though, so most of the MRIs are taken without contrast and then another with contrast if necessary. They have known about various side effects of contrast for some years (allergies, etc).
With MS, active lesions enhance and old, inactive ones don’t.
There are a lot uses for contrast in brain imaging and it is very helpful.
Gadolinium deposition obviously isn’t great.