5 ms·

One of the key findings coming out of China is that CT scans can outperform reverse-transcription polymerase chain reaction (RT-PCR) lab tests in diagnosing th

by Leary 7y ago

One of the key findings coming out of China is that CT scans can outperform reverse-transcription polymerase chain reaction (RT-PCR) lab tests in diagnosing the Coronavirus[1]. [1]https://www.itnonline.com/content/ct-provides-best-diagnosis-novel-coronavirus-covid-19 https://www.itnonline.com/content/ct-provides-best-diagnosis... If the CDC's current tests are flawed or too few, then the CDC should provide guidelines to health providers to quickly diagnose potential patients using CT scans.

mnm1 7y ago
A CT scan is fairly standard procedure for diagnosing many things. Why do doctors and hospitals need CDC permission to use it to test? This seems like a bad movie where the CDC is not doing much due to political pressure. Why can't doctors act in their patients' best interest on their own?
- eganist 7y ago
  If you want to see the outcome of a country's health department ignoring this outbreak for political purposes, look no further than Iran. https://www.newyorker.com/news/our-columnists/how-iran-became-a-new-epicenter-of-the-coronavirus-outbreak https://www.newyorker.com/news/our-columnists/how-iran-becam...
- semi-extrinsic 7y ago
  A CT has a pretty high radiation dose. As far as I understand, for every 2000 people given a chest CT we expect 1 person to get a fatal form of cancer due to the CT. Compared to the natural incidence of getting a fatal cancer in your lifetime (about 400 in 2000), this is a very low. And for serious conditions, a CT can literally be a life saver. But if you apply chest CTs to screen for a disease with (let's say) a 0.1% fatality rate, the side effects of your screening increases the fatality rate by 50%.
  - eganist 7y ago
    From what we can tell, SARS-CoV-2 has a 2% mortality rate among those diagnosed. That seems like a pretty decent trade in odds if it accelerates early stage treatment.
    - scottlocklin 7y ago
      Considering you just read an article on how the CDC has told people to not test people who aren't obviously going to die, you may want to revise that figure downward some out of sample bias.
    - kalipsosu 7y ago
      2% within confirmed cases. There is a part of the iceberg which we cannot see because mild cases will not seek care. Actual mortality rate is far lower than that. You should check mortality rate for outside wuhan population. It is 0.08%
      - ciceryadam 7y ago
        Italy's 52 deaths vs 1900 cases is higher than 2% - https://www.theguardian.com/world/2020/mar/02/italys-coronavirus-death-toll-rises https://www.theguardian.com/world/2020/mar/02/italys-coronav...
  - anonsivalley652 7y ago
    It's ~29000 deaths / 70M CT scans per year. That's 414 micromorts, which is almost exactly as risky as skydiving once on average. https://en.wikipedia.org/wiki/Micromort https://en.wikipedia.org/wiki/Micromort Source: US NCI 2007
    - jonas21 7y ago
      The wikipedia article says skydiving is 8 micromorts per jump. So more like skydiving 50 times?
      - medymed 7y ago
        I don’t think biologic math always works combinatorially like multiple sky dives. This sometime troubles me with radiation dosing comparisons. Another is time distribution, when a radiologic imaging study is equated with exposure from X amount of time in an airplane at high altitude. The time frames are different—- drinking 1 liter of water in an hour is usually safe, and drinking 50 liters of water is fine spaced out over a longer time period—-but not 50 liters over an hour. Radiation doses are often quite time dense.
    - semi-extrinsic 7y ago
      Yeah, 1 in 2000 is 500 micromorts, somewhere in the 400-500 micromorts region.
  - antognini 7y ago
    Yes, the rule of thumb I know is that you can get about 25 CT scans in your lifetime before having a significantly increased risk of cancer. By contrast you can get about 25,000 chest X-rays.
riahi 7y ago
As someone who interprets CTs, the findings described in that paper are totally nonspecific and just indicate a pulmonary infectious/inflammatory process. The takeaway I have is if the CT is totally clear, COVID is unlikely. Otherwise, you need confirmatory testing to figure out what is going on with the lungs.
kalipsosu 7y ago
CT changes did not occur before disease progression. In one study it occurs after 3-5 days after being admitted to hospital.(I could not find the link right now sorry.) Therefore cannot be use for 'quickly diagnosing'

by Leary 7y ago

mnm1 7y ago

A CT scan is fairly standard procedure for diagnosing many things. Why do doctors and hospitals need CDC permission to use it to test? This seems like a bad movie where the CDC is not doing much due to political pressure. Why can't doctors act in their patients' best interest on their own?

eganist 7y ago
If you want to see the outcome of a country's health department ignoring this outbreak for political purposes, look no further than Iran. https://www.newyorker.com/news/our-columnists/how-iran-became-a-new-epicenter-of-the-coronavirus-outbreak https://www.newyorker.com/news/our-columnists/how-iran-becam...
semi-extrinsic 7y ago
A CT has a pretty high radiation dose. As far as I understand, for every 2000 people given a chest CT we expect 1 person to get a fatal form of cancer due to the CT. Compared to the natural incidence of getting a fatal cancer in your lifetime (about 400 in 2000), this is a very low. And for serious conditions, a CT can literally be a life saver. But if you apply chest CTs to screen for a disease with (let's say) a 0.1% fatality rate, the side effects of your screening increases the fatality rate by 50%.
- eganist 7y ago
  From what we can tell, SARS-CoV-2 has a 2% mortality rate among those diagnosed. That seems like a pretty decent trade in odds if it accelerates early stage treatment.
  - scottlocklin 7y ago
    Considering you just read an article on how the CDC has told people to not test people who aren't obviously going to die, you may want to revise that figure downward some out of sample bias.
  - kalipsosu 7y ago
    2% within confirmed cases. There is a part of the iceberg which we cannot see because mild cases will not seek care. Actual mortality rate is far lower than that. You should check mortality rate for outside wuhan population. It is 0.08%
    - ciceryadam 7y ago
      Italy's 52 deaths vs 1900 cases is higher than 2% - https://www.theguardian.com/world/2020/mar/02/italys-coronavirus-death-toll-rises https://www.theguardian.com/world/2020/mar/02/italys-coronav...
- anonsivalley652 7y ago
  It's ~29000 deaths / 70M CT scans per year. That's 414 micromorts, which is almost exactly as risky as skydiving once on average. https://en.wikipedia.org/wiki/Micromort https://en.wikipedia.org/wiki/Micromort Source: US NCI 2007
  - jonas21 7y ago
    The wikipedia article says skydiving is 8 micromorts per jump. So more like skydiving 50 times?
    - medymed 7y ago
      I don’t think biologic math always works combinatorially like multiple sky dives. This sometime troubles me with radiation dosing comparisons. Another is time distribution, when a radiologic imaging study is equated with exposure from X amount of time in an airplane at high altitude. The time frames are different—- drinking 1 liter of water in an hour is usually safe, and drinking 50 liters of water is fine spaced out over a longer time period—-but not 50 liters over an hour. Radiation doses are often quite time dense.
  - semi-extrinsic 7y ago
    Yeah, 1 in 2000 is 500 micromorts, somewhere in the 400-500 micromorts region.
- antognini 7y ago
  Yes, the rule of thumb I know is that you can get about 25 CT scans in your lifetime before having a significantly increased risk of cancer. By contrast you can get about 25,000 chest X-rays.

riahi 7y ago

As someone who interprets CTs, the findings described in that paper are totally nonspecific and just indicate a pulmonary infectious/inflammatory process. The takeaway I have is if the CT is totally clear, COVID is unlikely. Otherwise, you need confirmatory testing to figure out what is going on with the lungs.

kalipsosu 7y ago

CT changes did not occur before disease progression. In one study it occurs after 3-5 days after being admitted to hospital.(I could not find the link right now sorry.) Therefore cannot be use for 'quickly diagnosing'