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One whole-body MRI could replace multiple cancer scans

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Re: One whole-body MRI could replace multiple cancer scans

#121

Post by abecedarius »

mattkrause wrote: post #114
abecedarius wrote: post #101

Earlier quoted context omitted.

For a rational agent the expected value of information is never negative. (Of course it can be less than the cost of the test.) If a system is treating it as negative, that's a problem to fix. I'm reminded of a recent visit to a doctor who refused to say anything quantitative about a test. Sure, your average client knows little decision theory, but this doctor either didn't either or pretended not to follow. To make…

We could do an autopsy on you right now if you want. How sure are you that you just stubbed your toe and it's not some highly metastasized cancer?

"Of course it can be less than the cost of the test." includes non-monetary costs. I thought this was clear since the benefit we're talking about is obviously not wholly monetary. (Or even mostly.)

Re: One whole-body MRI could replace multiple cancer scans

#122

Post by abakker »

concernedstats wrote: post #95
jmhmd wrote: post #91

Earlier quoted context omitted.

The idea that lots of full body MRIs will necessarily lead to better discrimination of malignant vs benign anomalies assumes that the imaging is able to detect differences at all, which often is not true. Some benign and malignant abnormalities can look _exactly_ the same on imaging, particularly at an early stage, when you could make a difference, for example lung nodules. Nevermind the fact that many benign entitie…

I think their statement is more general than what you're making it out to be. The goal of receiving better and more data puts pressure to have better imaging technology.

I think there are perverse incentives at work, too. If running the MRI machine cost $100, people would do it. If it can bill insurance $100k, and then any follow up might cost $500k, there is a rational aversion to doing it as it might make the _system_ less good for everyone if insurance cracked down on exploratory imaging as a billable thing (obviously, they already do this to some extent).

Better technology is unlikely to be cheaper, unless it is so new and novel that it can get its own unique billing codes, and if it becomes ubiquitous so it cheaper and more available than existing machines which are not yet depreciated.

Just typing that out depresses me.

Re: One whole-body MRI could replace multiple cancer scans

#123

Post by DanBC »

jedberg wrote: post #111

I've had this idea floating in my head for a while. Provide free annual full body MRIs to people, including being read by a radiologist, which they can take to anyone they want (doctor, lawyer, whatever). In exchange, they agree to send the org a copy of all their past and future medical records. The records are anonymized and tied to the MRIs. The MRIs and medical data is then pumped through machine learning algorit…

> annual full body MRIs to people

So, these are not medically indicated scans which means you're going to be causing huge amounts of over-diagnosis and thus over-treatment, which cause harm.

Hypothetical Bob has his first scan, and it returns a few shadows on his lung. The doctors ask if he's ever had chicken pox and he doesn't think so but he's not sure. So, these shadows are probably just scaring from chicken pox. But maybe they're cancer. The only sure way to tell is for a biopsy. Every medical intervention carries risk, and because you've increased the numbers of interventions you've increased the numbers of people falling victim to that risk.

Bob got a scare; he got an unnecessary medical intervention; he was subjected to risk: what did Bob gain from this?

The only thing this extra data tells us is "chicken pox sometimes scars the lungs and they sometimes show up on MRI", which is something we already know.

You do have a good point about the difficulty in getting hold of data to train AI. Sadly, because of recent missteps in England that's going to continue to be difficult unless the company can show rigorous protections.

Re: One whole-body MRI could replace multiple cancer scans

#124

Post by DanBC »

Here's the NIHR blog: https://www.nihr.ac.uk/blogs/does-how-we-detect-the-spread-o...

And here's the paper: https://www.journalslibrary.nihr.ac.uk/programmes/hta/106801...

These are worth reading, they're in more detail than the submitted site. I recommend NIHR because they're usually short and very readable.

Re: One whole-body MRI could replace multiple cancer scans

#125

Post by copperx »

mattkrause wrote: post #104
stevesimmons wrote: post #92

Earlier quoted context omitted.

Even if we can't reliably compare a time series of images today, wouldn't it be useful to start scanning now, for use as baselines in several years once the state of the art improves? In the same way astronomers can make new discoveries by digitizing photographic plates from a century ago.

Nope. Really, it's a question of priorities. Scanners cost a lot: ~4M for a 3T (the current 'standard') and much more for higher field strengths. We just got a 7T and, with all the trimmings (scanner, console, coils, the shielded room to hold it all, training, etc), it's in the $10-15M range. As a result, time on these things is already in pretty high demand, even at facilities that are used only for research. The pr…

> We just got a 7T

Where is that? Might be worth the trip in some cases.

Re: One whole-body MRI could replace multiple cancer scans

#126

Post by Brakenshire »

louden wrote: post #118
nnq wrote: post #115

Earlier quoted context omitted.

MDs are idiots in this regard. Mainly because they've been thought medicine by other idiots. They have this stupid idea that "too much data" is bad, also stuff being a sign that you're a bad doctor if you order too much tests etc. It's a whole can of worms of crappy rationalizations here, that also hides the fact that doctors are not capable or trained to correctly deal with large volumes of data, so they know they w…

More data is not always better. The collection process itself can be dangerous or unpleasant for the patient. Several years ago I worked on a study looking at the spread of bacterial lung infections in long term hospital patient. In order to get the data, we would have to intubate patients that did not need it. In this case, the people who approve these studies rightfully ruled that getting that data would be too pai…

> The collection process itself can be dangerous or unpleasant for the patient.

That’s asinine, obviously he doesn’t mean more data is always better even if the test is invasive or dangerous.

> Biopsies caused by benign findings from a full body scan are not without pain, emotional distress, risk or cost to the patient. Period. It must be weighed against the benefit that the patient would recieve (all in the aggregate, or course).

Both need to be judged on time and cost, but only the biopsy needs to be weighed against risk, not the scan. If people see a scan with anomalies and want dangerous procedures even if the risk is not demonstrated that is a cultural, education, and legal problem. Both for doctors wanting to avoid malpractice ordering unjustified tests, and for patients “wanting it out”.

But if the scan can demonstrate some marginal elevated risk, not the need for immediate intervention but for increased screening, that data could potentially save many lives, and it should be used, not hidden away because of the possibility of overreaction. Researchers need to find how best to use the data and patients and doctors need to be educated in our current best understanding, not pandered to.

Re: One whole-body MRI could replace multiple cancer scans

#127

Post by codingdave »

jedberg wrote: post #111

I've had this idea floating in my head for a while. Provide free annual full body MRIs to people, including being read by a radiologist, which they can take to anyone they want (doctor, lawyer, whatever). In exchange, they agree to send the org a copy of all their past and future medical records. The records are anonymized and tied to the MRIs. The MRIs and medical data is then pumped through machine learning algorit…

> agree to send the org a copy of all their past and future medical records..

Even ignoring the issue of false positives, which alone is serious enough to make this a dubious idea... that is an extreme thing to ask of people. All my future records? I have no idea what my future holds, and what I may feel about that as I age and experience new problems. Nor how my family might feel about it on my deathbed.

I applaud new ways to for early detection of problems, but not like this.

Re: One whole-body MRI could replace multiple cancer scans

#128

Post by canada_dry »

paulsutter wrote: post #52
nknealk wrote: post #13

Many doctors hate full body scans. Every individual has a handful of anomalies which are almost always benign. They show up on full body scans and chasing them down comes with cost and patient risk. I have a hard time with reporting like this that doesn't quantify cost of biopsy on false-positives as well as cost of complications from examining false-positives. Source: worked in clinical research for 2 years.

You're describing a problem with the doctors, not a problem with the scans. I'm curious to understand the real motivation to avoid information. Is it something in the system, litigation risk? There are many ways to deal with incidentalomas. If full body scans were more widespread, maybe doctors would have confidence to deal with them properly. For example, watching them over time.

> watching them over time

In my mind this is the key... a way to frequently and conveniently do a full body scan so that anomalies can be detected via the delta. Scanning and detection is a problem that likely could be tackled via machine learning.

I'm hoping it's not too long before a method is developed where a low res MRI like scan is feasible at home (e.g. using radio or ultrasound).

Done on a regular basis the system could detect anomalies like the appearance or enlargement of a growth inside the body.

Re: One whole-body MRI could replace multiple cancer scans

#129

Post by jedberg »

DanBC wrote: post #123
jedberg wrote: post #111

I've had this idea floating in my head for a while. Provide free annual full body MRIs to people, including being read by a radiologist, which they can take to anyone they want (doctor, lawyer, whatever). In exchange, they agree to send the org a copy of all their past and future medical records. The records are anonymized and tied to the MRIs. The MRIs and medical data is then pumped through machine learning algorit…

> annual full body MRIs to people So, these are not medically indicated scans which means you're going to be causing huge amounts of over-diagnosis and thus over-treatment, which cause harm. Hypothetical Bob has his first scan, and it returns a few shadows on his lung. The doctors ask if he's ever had chicken pox and he doesn't think so but he's not sure. So, these shadows are probably just scaring from chicken pox.…

> So, these are not medically indicated scans which means you're going to be causing huge amounts of over-diagnosis and thus over-treatment, which cause harm.

What if we did something like set up a system where Bob's doctor can put in other symptoms, and only if one shows up that would indicate a lung MRI would the doctor be told, "Oh hey, we already did that, here's the MRI, and there was some shadow on the lung"?

Re: One whole-body MRI could replace multiple cancer scans

#130

Post by epistasis »

Brakenshire wrote: post #126
louden wrote: post #118

Earlier quoted context omitted.

More data is not always better. The collection process itself can be dangerous or unpleasant for the patient. Several years ago I worked on a study looking at the spread of bacterial lung infections in long term hospital patient. In order to get the data, we would have to intubate patients that did not need it. In this case, the people who approve these studies rightfully ruled that getting that data would be too pai…

> The collection process itself can be dangerous or unpleasant for the patient. That’s asinine, obviously he doesn’t mean more data is always better even if the test is invasive or dangerous. > Biopsies caused by benign findings from a full body scan are not without pain, emotional distress, risk or cost to the patient. Period. It must be weighed against the benefit that the patient would recieve (all in the aggregat…

> but only the biopsy needs to be weighed against risk, not the scan.

You're setting an arbitrary boundary because you don't want to consider the downsides. If you set the same boundary on the benefits of the MRI, then you wouldn't be able to include treatment of cancer as part of the upside to doing an MRI scan.

Doctors are far wiser about these things than HN commenters that have never dealt with the complex tradeoffs of dealing not only with populations of people, but also with dealing with the psychology of humans beyond people that prioritize rationality over everything else.

Doctors are responsible for treating all of humanity, not just the subset that behave the way we want them to.

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