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How often do full-body MRIs find cancer?

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Re: How often do full-body MRIs find cancer?

#131

Post by lostlogin »

cyberax wrote: post #22
p0pularopinion wrote: post #18

Earlier quoted context omitted.

The problem is that just because you‘re detecting something, it does not mean it is worth watching. Bodies are not standardized and most people habe something off. But you can‘t really reschedule everybody constantly, as that would entirely break the concept.

"Worth watching" implies that watching is expensive. It's really not. A full-body MRI scan is about $1k, and it can be even cheaper. So if you have abnormal findings in 10% of patients that merit follow-up scans, you can trivially do a series of 3-4 scans without affecting the overall cost too much. Doctors simply need to get out of the headspace where MRIs are extremely scarce tools of last resort and treat them lik…

> MRIs are extremely scarce tools of last resort and treat them like we treat blood tests.

How would this work?

I can do a blood test and send it to the lab to be processed in ~5 minutes from the moment I meet the patient. Consumable costs are about $2.

I can also do an MR scan. It took a fair bit of training and the scanner and scan room cost about US$2 million. Service contracts on the scanner, scan room, chillers and required staffing utterly dwarf the cost of the scanner over its lifetime.

The scan takes 20-75 minutes. Then the images get sent for reporting. Unlike a blood test, reporting isn’t automated. Even if it was, how could availability of MR ever be similar to a blood test?

Re: How often do full-body MRIs find cancer?

#132

Post by srdjanr »

Can one solution be always doing two scans, N months apart, before drawing any conclusions (excluding things that can be reliably detected from a single scan)? Initial scan could affect N (if you find something potentially aggressive, you can schedule the second scan sooner). And then do a follow up every M years.

That should exclude benign or very slowing growing things

Re: How often do full-body MRIs find cancer?

#133

Post by tjpnz »

mmaunder wrote: post #13

“ One study in 2020 found that 95% of asymptomatic patients had some type of "abnormal" finding, but just 1.8% of these findings were indeed cancer.” This has been my experience. And I’ve had oncologists echo exactly this. In the words of one: MRIs find too much. The CT and the PET/CT are the gold standards for finding cancer, finding recurrences, and staging cancer. The trouble is the radiation dose. MRI provides ve…

>MRIs are great for certain things like herniated disks in your back. They suck at cancer.

MRIs are fine for certain kinds of cancer like liver cancer.

Re: How often do full-body MRIs find cancer?

#134

Post by tjpnz »

lostlogin wrote: post #74
mgraczyk wrote: post #25

Earlier quoted context omitted.

And yes getting frequent full body MRIs is still overwhelming the right thing for the patient.

Here in NZ an Australia, the college of radiologists disagree and say ‘don’t do it’ for screening the worried well. https://www.ranzcr.com/college/document-library/2024-positio...

NZ doesn't have the screening capacity for when it's medically necessary, much less optional.

Re: How often do full-body MRIs find cancer?

#135

Post by kcexn »

nayroclade wrote: post #129

Arguments against proactive MRI scanning always seem to have a whiff of status quo bias to them. Yes, right now MRIs are expensive and false positives are common, but if regular scans were widespread, it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. To use a software analogy…

There's a softer component to healthcare which is that people can overreact to medical results. If a doctor administers a scan, finds a handful of likely benign things but wants to administer another scan later on down the line, I'm probably much more likely to look for a second opinion that tells me to cut them out (even if it may not be medically necessary) than trust my doctor that "it's probably fine".

It's probably more accurate to use a software analogy about performance metrics. We measure random request spikes now and again that strain the system. It's probably fine, but later on down the line, something could change that results in an outage during one of these spikes. Do we proactively fix the problem even if no change is expected? Or do we wait till there is definitely a problem before taking action?

Re: How often do full-body MRIs find cancer?

#136

Post by srean »

nayroclade wrote: post #129

Arguments against proactive MRI scanning always seem to have a whiff of status quo bias to them. Yes, right now MRIs are expensive and false positives are common, but if regular scans were widespread, it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. To use a software analogy…

False positives trigger more diagnostics some of which can be harmful, not just psychologically but physiologically as well.

If false positives are ok, why not build a down time detector that rolls a die every 5 mins and alert on hitting a 6.

Re: How often do full-body MRIs find cancer?

#137

Post by azan_ »

mmaunder wrote: post #13

“ One study in 2020 found that 95% of asymptomatic patients had some type of "abnormal" finding, but just 1.8% of these findings were indeed cancer.” This has been my experience. And I’ve had oncologists echo exactly this. In the words of one: MRIs find too much. The CT and the PET/CT are the gold standards for finding cancer, finding recurrences, and staging cancer. The trouble is the radiation dose. MRI provides ve…

That’s completely and 100% false. It’s much easier to characterize things on MRI and MRI is indeed phenomenal for cancer! The problem is with screening, not actual staging or follow-up, and whole-body screening in ct and pet/ct is even worse than MRI screening even if you ignore radiation.

Re: How often do full-body MRIs find cancer?

#138

Post by azan_ »

ErroneousBosh wrote: post #122
rustyhancock wrote: post #53

Earlier quoted context omitted.

It's not that MRIs suck at cancer. They provide fantastic structural and functional data. The problem is the specificity of the results and the prior. A full body MRI by definition will provide detailed views of areas where the pretest probability for cancer is negligible. That means even a specific test would result in a high risk of false positives. As a counter point, MRS means that you can now MRI someone's prost…

> The danger of an unnecessary CT/PET is causing cancer You'd have to be massively overexposed to CT or PET scanning to cause cancer, like in the region of spending months being scanned continuously with it at full beam current.

Approx. 5% of all cancers in US are caused by CTs

Re: How often do full-body MRIs find cancer?

#139

Post by jb1991 »

srean wrote: post #136
nayroclade wrote: post #129

Arguments against proactive MRI scanning always seem to have a whiff of status quo bias to them. Yes, right now MRIs are expensive and false positives are common, but if regular scans were widespread, it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. To use a software analogy…

False positives trigger more diagnostics some of which can be harmful, not just psychologically but physiologically as well. If false positives are ok, why not build a down time detector that rolls a die every 5 mins and alert on hitting a 6.

Additional diagnostics can also be very expensive. Articles like this don’t seem to understand the overall costs to a health system with decisions like these. And that cost eventually does go down into the pockets of patients one way or another.

Re: How often do full-body MRIs find cancer?

#140

Post by robocat »

mcbain wrote: post #24
p0pularopinion wrote: post #17

Earlier quoted context omitted.

> My father is a part of "full body PET scan every 3 years" program as part of post - cancer treatment, These treatments are wonderful and it is great that they exist. But many people fail to understand the difference in terms of pretest probability, etc. I can absolutely see the heavy psychological impact pending biopsy results may have. People are quick to discount these issues when you raise them as a concern, but…

I have multiple scans a year. "Scanxiety" is real.

> Scanxiety

Cute written word - even though two words pronounced completely differently at join (an versus añ).

Which do you pronounce correctly the scan or the anxiety? [scan]xiety or [sk]anxiety

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