
AI can detect coronavirus from CT scans in twenty seconds - laurex
https://www.linkedin.com/pulse/ai-can-detect-corona-virus-from-ct-scans-just-20-seconds-alan-brown/
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doctoring
So many things.

"It takes doctors around 20 mins to do the same" is patently false. I would
say a full review and dictation of a chest CT by a trained radiologist
takes... 10 minutes? 20 if really complicated (metastatic cancer). But for the
radiologist to decide whether or not there were findings compatible with
COVID-19 (i.e. what this algorithm is performing) would probably take seconds.

In fact, you could probably train almost any adult (and probably most
children!) to distinguish between "possibly COVID" and "no COVID" lung CTs
very quickly.

However, as pointed out elsewhere, the presence of these findings (such as
what we call "ground glass opacities" \-- which is just a fancy/weird way to
describe areas that are slightly less transparent than normal lung but not
quite opaque) is not specific at all. They can be caused by COVID-19 or any
number of other viral or fungal lung infections, as well as by reactions to
drugs, hemorrhage or edema in the lungs, and so on.

A positive CT would almost certainly require a confirmatory COVID-19 test. A
negative CT scan in a patient with symptoms... would still demand a COVID-19
test, because findings in the lungs often lag behind the infection.

So CT doesn't change your decision-making in the screening process. And they
are time-consuming, costly, and harmful (they use radiation!). Their utility
in caring for COVID-19 patients is probably to assess severity of disease,
monitor response, and to rule out additional pathologies in the lungs. (Not to
say AI couldn't help with those!)

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jcampbell1
> And they are time-consuming, costly, and harmful (they use radiation!)

To put things in perspective, I got a CT in China, and the imaging took less
than 5 minutes, and cost $35 (just the machine, not reading). The radiation is
less than the increased radiation than taking a flight to China.

While your perspective is probably accurate for the US, if you step back and
think, it is no more complicated than getting grade school photos.

~~~
projektfu
By my math, a chest CT is about 10x the dose from a flight. However, there is
no “safe” level of ionizing radiation. There is only acceptable and
unacceptable risk.

~~~
jcampbell1
A lung CT can be done at about 1/5th the radiation dose of a chest CT. The
future will decide if we took the correct risk with extremely limited testing
in the early stages.

In my experience, “not my job” , “too much risk”, and “need more data to make
a decision“ is the default attitude in the medical profession. People choose
that career because it is safe, and very few doctors have military experience
these days. That being said, people adjust to a new reality very quickly.

~~~
projektfu
By the time pneumonia has occurred it’s too late for screening. This isn’t
replacing rtPCR for people who are coughing.

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dontreact
CT will not play a role in the diagnosis of Coronavirus in the US now that
both the ACR and Society of Thiracic radiologists have come out not
recommending it for first line diagnosis. This is a complex decision involving
the availability of other tests, the potential for spread via contamination of
CT, the need for CT for other things and the limited availability of scanners.

There is a group that will open source a great dataset first this sometime
soon, as it might be useful in other countries.

~~~
ztratar
Why is this, even though it was so prevalent in China as a key signal for
testing?

~~~
dontreact
I agree that it’s surprising. Medical establishment in the US is much more
conservative.

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scythe
This is cool, but as a medical physics student, it has been repeatedly
emphasized to me that CT scans are extremely dangerous and usually considered
the "imaging of last resort" when no other method is appropriate. The risk of
cancer from a single CT scan can vary from 0.01%-0.4%, bringing it near the
risk of death from COVID-19:

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4635397/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4635397/)

> _An estimated 1 in 270 women who underwent a coronary angiography CT at age
> 40 will develop cancer from that CT (1 in 600 men), compared with an
> estimated 1 in 8,100 women who had routine head CT at the same age (1 in 11,
> 080 men)._

CT scans might just be the _worst_ possible way to detect the coronavirus.

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chrisa
As the first comment there points out, a 96% accuracy doesn't mean much
without knowing the false positive and false negative rates.

I have no doubt that this is good work in the right direction - but the
headline alone doesn't make it a home run.

~~~
mike_n
Do human doctors have a better rate? And at what cost/throughput?

~~~
jupp0r
This is the base rate fallacy.

    
    
        return “healthy”;
    

would have a 99.9% accuracy right now.

~~~
yellow_lead
I think you have a good idea for an AI startup here.

~~~
smacktoward
For bonus points, have it return one out of every 1000 or so requests with
"not hot dog."

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adrianmonk
Speaking of AI and coronavirus detection, some Chinese tech companies (Megvii,
Baidu, SenseTime) have apparently built systems to detect fever with thermal
imaging cameras and AI.

[https://www.scmp.com/tech/policy/article/3049215/ai-firms-
de...](https://www.scmp.com/tech/policy/article/3049215/ai-firms-deploy-fever-
detection-systems-beijing-help-fight-coronavirus)

[https://www.bbc.com/news/technology-51717164](https://www.bbc.com/news/technology-51717164)

Seems like something that could be useful anywhere. Ideally, people would
self-regulate (go to the doctor, isolate themselves, etc.), but in practice
extra layers of protection seem smart. People may not immediately realize
they're sick, they might go out anyway, etc.

This seems to, in China's case, tie in with facial recognition they already do
(which has privacy implications), but there's no reason the rest of the world
would have to approach it that way.

~~~
MaxBarraclough
It's possible to have the virus without showing significant symptoms, isn't
it? Either because you just recently caught it, or because you happen to be
lucky enough to have only minimal symptoms. Doesn't that undermine
temperature-based detection?

~~~
adrianmonk
Yeah, for sure it can't be 100% effective.

I suppose what really matters is out of all the infected (or more precisely,
contagious) people, what percentage of them have a fever. If it's 10%, then
it's not worth doing. If it's even 50%, then maybe it could make a significant
difference.

Fever is one of the three main symptoms
([https://www.cdc.gov/coronavirus/2019-ncov/about/symptoms.htm...](https://www.cdc.gov/coronavirus/2019-ncov/about/symptoms.html)),
so it seems like it has to at least be a significant percentage. But just how
high a percentage, I don't know.

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rediguanayum
IANAD but just keep in mind that CT scans isn't specific Covid-19, rather that
it detects telltale damage done by the virus but also could be done by other
respiratory viral disease. Only in places where Covid-19 is widespread, one
might assume a positive test result indicates Covid-19 in the patient.

~~~
Engineering-MD
It shows an atypical pneumonia. I believe this appearance in combination with
a lack of cultures for other pathogens which do this was how Covid was first
suspected in China in December.

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anderson123
Is there a possible way to identify COVID-19 without a Chest CT scan? For
those infected, a Chest CT is an added burden, and for those not infected, it
would be unnecessary effects of radiation. However, the use of AI to identify
COVID-19 within 20 seconds is a good way to use technology during a crisis. We
offer awareness and CT Chest scans at
[https://www.andersondiagnostics.com/](https://www.andersondiagnostics.com/)
for added safety.

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bradleybuda
A good heuristic is, don’t get your medical news from LinkedIn. Doubly-so if
the word “AI” appears in the headline.

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duxup
Isn't a CT scan kind of an ordeal to do?

~~~
DigitalVerse
Agreed... seems like the bottleneck is the cost and time to run the CT scan,
not to have a doctor look at the results.

~~~
tguvot
in china they were running partial ct scans: 5min per patient. Usually it's
30+

~~~
riahi
Sorry, modern CT scans are < 20 seconds. The really great scanners are 10
seconds.

~~~
tguvot
had a couple of CT myself. Usually it's minutes of active scanning. But all
the preparations/calibrations/whatever is done - you stay in machine at least
half an hour+. They cut it down to 5.

~~~
riahi
Are you sure you aren’t mixing up CT and MRI? Our scheduled diagnostic CT
slots are at every 15 minutes, of which probably 10 minutes are getting the
patient on-off the table and positioned and 2 minutes are cleaning the room.

I do CT guided procedures every day. It’s seconds for data acquisition for any
scanner made in the last 15 years. Even our ancient scanners from the early
2000s are this fast.

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esjeon
The thing is that, not all COVID-19 patients will suffer viral pneumonia, and
lung damages are only visible in later stages of infection, when you would not
need a doctor to realize you're infected. What's the point of this?

EDIT: Hmm, so it seems like CT is more accurate than current test kits, which
reportedly result in many false negatives. Yet, I found that other AI
companies had already made their own models, with 90 ~ 97.6% accuracy[1].

[1]:
[https://translate.google.com/translate?sl=auto&tl=en&u=http%...](https://translate.google.com/translate?sl=auto&tl=en&u=http%3A%2F%2Fwww.biotimes.co.kr%2Fnews%2FarticleView.html%3Fidxno%3D3154)

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avip
Spoiler: "X can do Y" is not the same as "random dude on LI says random
company says X can do Y given Z without providing any relevant numbers"

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hprotagonist
accuracy don't mean shit. give me precision and recall too or you're just
picking numbers.

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riahi
Can it differentiate between all the various types of atypical infection?
Because the findings of COVID are nonspecific viral pneumonia, which could
literally be any atypical infectious/inflammatory process.

CT only has great sensitivity; it has terrible specificity.

Anyone have the paper?

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westurner
Is it possible to detect coronavirus with NIRS (Near-Infrared Spectroscopy)?
[https://en.wikipedia.org/wiki/Near-
infrared_spectroscopy](https://en.wikipedia.org/wiki/Near-
infrared_spectroscopy)

FWIU, the equipment costs and scan times are lower with NIRS than with CT or
MRI? And infrared is zero rads?

(Edit) I think it was this or the TED video that had the sweet demo: "The
Science of Visible Thought & Our Translucent Selves | Mary Lou Jepsen | SU
Global Summit" [https://youtu.be/IRCXNBzfeC4](https://youtu.be/IRCXNBzfeC4)

Are these devices in production?

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DerSaidin
CT scan room and machine is going to need a lot of cleaning.

~~~
mattkrause
I've read that that's the real bottleneck--you need to clean the bejesus out
of the machine if you don't want it becoming part of the problem.

The actual scanning itself only takes a moment. We do head ones and they're
surprisingly fast once everything's ready to go.

~~~
Gibbon1
I saw a summary of China's efforts, supposedly before they had enough testing
available they were at one point running 300-400 patients a day through each
CT machine in Wuhan.

That's one every 4 minutes.

~~~
mattkrause
Do you know if they did anything clever to keep the scanners clean?

I wonder if you could somehow isolate the patient rather than deep-clean the
machine (ours has some exposed moving parts, which would make that time-
consuming, but perhaps the non-research ones are better designed).

~~~
Gibbon1
> isolate the patient

That's what I would do. Someone else that claims to be a radiology tech said
you just need to wipe the machine down for SARS since it's spread by droplets
and fluids.

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blackrock
Props to these China AI scientists!

Even more impressive is that they were able to develop it in about 6-7 weeks
after the initial containment effort.

This is a win for AI, as a massive pattern recognition machine, to help reduce
the labor load of critical personnel, like radiologists. It helps by removing
them as the limiting factor, that would slow down a critical process.

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LordHumungous
A radiologist can do it in about the same time. It presents as "ground glass
opacities" which are pretty easy to spot.

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manicdee
Is this actually detecting COVID-19 or yellow rulers?

[https://www.ben-evans.com/benedictevans/2019/4/15/notes-
on-a...](https://www.ben-evans.com/benedictevans/2019/4/15/notes-on-ai-bias)

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lowdose
Would be awesome if radiology finally gets disrupted. 50% of hospital bills
can be attributed to the radiology department thus scalable innovation will
result in a more affordable healthcare service all round.

~~~
agoodthrowaway
It would be good but not sure that radiologists are the dominant cost.
Radiological equipment is heavily regulated because it can cause significant
harm to people if the equipment malfunctions.

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Gonzih
I think this is the case when false positives and false negatives can do a lot
of harm, so in human review of CT scan is a must. Especially if we consider
how small dataset this model is trained on.

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m3kw9
Only if you are way past symptomatic and have bilateral pneumonia. The CT scan
wait time is extra.

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luckylittle
Github, or it didn't happen

