4 ms·

MRI scans and blood tests are, but what comes next? If they find something there's always a least a follow-up biopsy, and often times what's seen on the screen

MRI scans and blood tests are, but what comes next? If they find something there's always a least a follow-up biopsy, and often times what's seen on the screen would have never impacted the person's life. Yes, there are outliers, but if you do enough scans you are guaranteed to find something wrong with you that you would never have known about otherwise.

kragen 3y ago
if the mri scans and blood tests show strong enough evidence of a problem that will impact your life that the risk outweighs the risk of the follow-up biopsy, you should get the biopsy if they don't you shouldn't so either you're better off or you're no worse off unless you have to be dealing with a doctor in cya mode
- SketchySeaBeast 3y ago
  I have some familiarity with diagnostic imaging - a lot of the time with these scans there's enough to say "yes, there is something there you should definitely get checked out" but you can't make a full assessment without a biopsy. The MRI is going to find things you need to investigate further. It'll also reveal a bunch of stuff you didn't need to know. Do you want to know about that minor slipped disc in your back that wasn't bothering you before? The nocebo effect is very real.
  - kragen 3y ago
    if investigating it further isn't worth the risk, you don't need to investigate further if investigating it further is worth the risk, then it's a good thing you did the scan this superstitious ideology that ignorance is good for you has always been popular; what's surprising is that some people still hold to it despite the industrial and scientific revolutions knowing about the minor slipped disc in your back might be important information if it starts hurting; you'll know it isn't a metastatic bone cancer. you might also be well advised to avoid taking up olympic weightlifting
    - SketchySeaBeast 3y ago
      > if investigating it further isn't worth the risk, you don't need to investigate further How do you make that call? What do you, as an eager but uneducated layman, use to decide that? You now know there's a heterogeneous cyst in your abdomen that the doctor says is super unlikely to be cancerous but it's not impossible that it could be. How do you evaluate your odds? Are you opting for the biopsy? If there's a dozen of such cysts in all corners of your body? Again, the MRI is a tool to help spot a problem, it's not going to give you the diagnosis.
      - kragen 3y ago
        usually i read the wikipedia articles about the disease and the common treatments, a couple dozen papers starting from google scholar via pubmed and sci-hub, maybe a relevant medical textbook via libgen. also talk to family members and friends about the issue. you can also find papers in medical journals and the mmwr on the prevalence of possible complications from different kinds of biopsies this takes a little longer than undergoing the biopsy, but it's enormously more pleasant, and it lets you know when doctors are ignorant or lying, which is perhaps even more important information. it's orders of magnitude easier than undergoing chemo and radiation so i don't know why 'eager but uneducated' laypeople don't always do it. maybe they're too used to living in a world without sci-hub and libgen it's also easier when it's not the first time it's never impossible that any part of your body could be cancerous, so 'super unlikely to be cancerous but it's not impossible that it could be' is a terrible justification for taking action
        SketchySeaBeast 3y ago
        > it's never impossible that any part of your body could be cancerous, so 'super unlikely to be cancerous but it's not impossible that it could be' is a terrible justification for taking action If you knew that you or your spouse had something that could be an issue but was unlikely to be - and it's nearly guaranteed that somewhere in your body right now you have stuff that would come back as "possibly a problem" in imaging - you'd be comfortable not taking action? I doubt that's how most people would response.
- ska 3y ago
  > strong enough evidence This is actually a bit subtle. For example I've heard more than one radiologist claim that if you look carefully, literally anyone's body scan will contain details that could justify work up. The fact is, if you do this broadly in a population and you work up everything you see that would justify it, some small number of people will die or suffer serious problems from complications of follow up. This is a fundamental problem in screening technologies (of any kind) with imperfect sensitivity. You can't get away from this, so you try and be clear that the net benefit is (much) higher. I'm not even against the idea of baseline scans, but the idea that this part is simple is naive.
  - kragen 3y ago
    that's just because the radiologists' standard for 'could justify work up' are too low
    - ska 3y ago
      Or it's because the problem is genuinely hard. See above ('imperfect sensitivity')... the same problem exists in e.g. blood tests. I'm no radiologist but I've seen enough of this done that I'd lean that way. Especially if you consider realistic bounds on time and additional information.
      - kragen 3y ago
        yes, of course the problem is genuinely hard, but having less information about your body makes it harder, not easier
        ska 3y ago
        In the abstract more information is always better. In practical healthcare with real constraints, sometimes it makes things worse globally for reason above. Think about say a diagnostic blood test with a poor sensitivity (but better than chance) on a very rare disease. As an oversimplification: for a bound take your population * workup rate * fatality rate due to workup and you have a baseline needless death due to the screening (NB there is basically always a fatality rate). The number you are comparing to is lives saved due to earlier detection. Better than chance means it's strictly more information always. But as policy, you shouldn't do it unless you can be extremely confident that lives saves is much larger than lives lost due to the process. This is a bit counter intuitive, but it is a fundamental issue in a lot of healthcare policy. The real calculations are more complex but in the end it is unavoidably actuarial in nature.

kragen 3y ago

if the mri scans and blood tests show strong enough evidence of a problem that will impact your life that the risk outweighs the risk of the follow-up biopsy, you should get the biopsy if they don't you shouldn't so either you're better off or you're no worse off unless you have to be dealing with a doctor in cya mode

SketchySeaBeast 3y ago
I have some familiarity with diagnostic imaging - a lot of the time with these scans there's enough to say "yes, there is something there you should definitely get checked out" but you can't make a full assessment without a biopsy. The MRI is going to find things you need to investigate further. It'll also reveal a bunch of stuff you didn't need to know. Do you want to know about that minor slipped disc in your back that wasn't bothering you before? The nocebo effect is very real.
- kragen 3y ago
  if investigating it further isn't worth the risk, you don't need to investigate further if investigating it further is worth the risk, then it's a good thing you did the scan this superstitious ideology that ignorance is good for you has always been popular; what's surprising is that some people still hold to it despite the industrial and scientific revolutions knowing about the minor slipped disc in your back might be important information if it starts hurting; you'll know it isn't a metastatic bone cancer. you might also be well advised to avoid taking up olympic weightlifting
  - SketchySeaBeast 3y ago
    > if investigating it further isn't worth the risk, you don't need to investigate further How do you make that call? What do you, as an eager but uneducated layman, use to decide that? You now know there's a heterogeneous cyst in your abdomen that the doctor says is super unlikely to be cancerous but it's not impossible that it could be. How do you evaluate your odds? Are you opting for the biopsy? If there's a dozen of such cysts in all corners of your body? Again, the MRI is a tool to help spot a problem, it's not going to give you the diagnosis.
    - kragen 3y ago
      usually i read the wikipedia articles about the disease and the common treatments, a couple dozen papers starting from google scholar via pubmed and sci-hub, maybe a relevant medical textbook via libgen. also talk to family members and friends about the issue. you can also find papers in medical journals and the mmwr on the prevalence of possible complications from different kinds of biopsies this takes a little longer than undergoing the biopsy, but it's enormously more pleasant, and it lets you know when doctors are ignorant or lying, which is perhaps even more important information. it's orders of magnitude easier than undergoing chemo and radiation so i don't know why 'eager but uneducated' laypeople don't always do it. maybe they're too used to living in a world without sci-hub and libgen it's also easier when it's not the first time it's never impossible that any part of your body could be cancerous, so 'super unlikely to be cancerous but it's not impossible that it could be' is a terrible justification for taking action
      - SketchySeaBeast 3y ago
        > it's never impossible that any part of your body could be cancerous, so 'super unlikely to be cancerous but it's not impossible that it could be' is a terrible justification for taking action If you knew that you or your spouse had something that could be an issue but was unlikely to be - and it's nearly guaranteed that somewhere in your body right now you have stuff that would come back as "possibly a problem" in imaging - you'd be comfortable not taking action? I doubt that's how most people would response.
ska 3y ago
> strong enough evidence This is actually a bit subtle. For example I've heard more than one radiologist claim that if you look carefully, literally anyone's body scan will contain details that could justify work up. The fact is, if you do this broadly in a population and you work up everything you see that would justify it, some small number of people will die or suffer serious problems from complications of follow up. This is a fundamental problem in screening technologies (of any kind) with imperfect sensitivity. You can't get away from this, so you try and be clear that the net benefit is (much) higher. I'm not even against the idea of baseline scans, but the idea that this part is simple is naive.
- kragen 3y ago
  that's just because the radiologists' standard for 'could justify work up' are too low
  - ska 3y ago
    Or it's because the problem is genuinely hard. See above ('imperfect sensitivity')... the same problem exists in e.g. blood tests. I'm no radiologist but I've seen enough of this done that I'd lean that way. Especially if you consider realistic bounds on time and additional information.
    - kragen 3y ago
      yes, of course the problem is genuinely hard, but having less information about your body makes it harder, not easier
      - ska 3y ago
        In the abstract more information is always better. In practical healthcare with real constraints, sometimes it makes things worse globally for reason above. Think about say a diagnostic blood test with a poor sensitivity (but better than chance) on a very rare disease. As an oversimplification: for a bound take your population * workup rate * fatality rate due to workup and you have a baseline needless death due to the screening (NB there is basically always a fatality rate). The number you are comparing to is lives saved due to earlier detection. Better than chance means it's strictly more information always. But as policy, you shouldn't do it unless you can be extremely confident that lives saves is much larger than lives lost due to the process. This is a bit counter intuitive, but it is a fundamental issue in a lot of healthcare policy. The real calculations are more complex but in the end it is unavoidably actuarial in nature.