Imaging Features of COVID-19

Imaging Features of COVID-19

As of March 16th, so in just the first three
months of the outbreak, there have been 167,511 cases of COVID-19 and 6,606 deaths, working
out to a mortality rate of 3.9%. On top of that, every case of COVID-19, leads to roughly
2.3 new cases, meaning that the outbreak is still spreading. Many countries have been
affected, and there are numerous cases of community spread, meaning that individuals
are getting sick without being around any sick contacts or having traveled to outbreak
areas. In that context, healthcare workers need diagnostic tools to investigate cases
of potential COVID-19 that are both sensitive and specific. The gold standard for diagnosis of COVID-19
is RT-PCR, or reverse transcription polymerase chain reaction. In the early days of the epidemic
in China RT-PCR was only 30 to 70% sensitive whereas Chest CT was reportedly much more
sensitive in that context. However, more recent data from the US labs at the University of
Washington suggests that second generation COVID RT-PCR tests are faring much better,
with 95%+ sensitivity. Despite its usefulness in the early days of the epidemic in China,
Chest CT findings are no longer part of the diagnostic criteria for COVID. There are still clearly issues with access
to RT-PCR and related wait times in the US and elsewhere. Nevertheless, over the past
several weeks, several major US radiology societies have come out with statements making
it clear that CT should be used sparingly in COVID and only when it will impact management. However, because there will be certain cases
when imaging is indicated, as well as patients imaged for other reasons whose scans reveal
findings potentially suggestive of COVID, it is essential that healthcare providers
be familiar with the imaging features of the infection. Typically, when a patient has symptoms of
COVID-19, like fever, cough, or shortness of breath, they may get a chest X-ray. The
most common abnormal finding is “ground glass” opacities, meaning that some portions
of the lungs look like a “hazy” shade of gray instead of being black with fine white
lung markings for blood vessels. It looks a bit like frosted glass, like a window in
the wintertime. It is important to note, however, that chest X-rays are not very sensitive for
COVID-19 and can yield false negatives. Now compared to chest X-rays, chest CT gives
a much more detailed view. The most common CT finding in COVID-19 are those ground-glass
opacities scattered throughout the lungs. They represent tiny air-sacs or alveoli getting
filled with fluid, and turning a shade of grey on a CT scan. In severe or more advanced infections, more
and more fluid will accumulate in the lobes of the lungs, so the ground glass appearance
will progress to a solid white “consolidation.” Finally, there’s a finding called the “crazy
paving” pattern due to swelling of the interstitial space along the walls of the lung lobules.
This makes the walls look thicker, like white lines against the hazy, ground glass background.
The appearance is similar to irregular shaped stones used to pave a street, hence the name
“crazy paving.” These three CT findings – ground glass opacities,
consolidations, and crazy paving patterns, can be seen in isolation or in combination
with one another. Ground glass is usually the first sign and is followed later by one
or both of the others. These findings usually occur in multiple lobes
throughout both lungs, and more commonly affect the outermost or periphery of the lungs. Having
said that, in mild or recovering cases of COVID-19, the findings can be isolated to
just one lobe. It’s no surprise then, that disease severity
is proportionate to the lung findings. The sickest individuals typically have the most
severe findings on chest CT. And as patients improve, there’s gradual resolution of the
ground glass and consolidations. Now, it’s worth mentioning that there are
some key CT findings that are usually not seen in n COVID-19, or at least seen less
often. You don’t usually see pleural effusions, which are fluid collections in the pleural
space right outside of the lungs. These are more common in conditions like congestive
heart failure and bacterial pneumonia. You also don’t see large lymph nodes in the
mediastinum or near the hilum or central part of the lung, which are often seen in other
types of pneumonia. Finally, you don’t typically see lung cavities, which usually develop in
bacterial and fungal pneumonia due to necrosis of the lung tissue later turning into an air-filled
cavity. Now, even though a chest CT is very sensitive
for COVID-19, the key findings, ground glass opacities, consolidations, and crazy paving,
can also be seen with other causes of viral pneumonia like influenza and adenovirus. They
can also be seen in a variety of non-infectious conditions. That means that chest CT is sensitive,
but not very specific for COVID-19, and that individuals with these findings should get
further clinical evaluation and laboratory tests done to exclude other causes. So as a quick recap. Chest CT is sensitive
for severe cases of COVID but not specific for COVID and should be performed only when
the referring physician feels it will impact management.d. The key findings on chest CT
include ground glass opacities, consolidations, and crazy paving. Individuals presenting to
hospitals with these chest CT findings may need isolation, and should get thorough confirmatory
testing and appropriate treatment.

44 Replies to “Imaging Features of COVID-19”

  1. Hi everyone, we've changed this video to update the current recommendations for when imaging should be used as part of diagnosis for COVID-19.

  2. Oh. just turned away from the live stream, where he talked about this video coming soon. well he wasnt wrong 😮 thx osmosis

  3. This is a real, great education video for people all over the world… 🙏. Thanks & many, many thanks… 🙏…

  4. Very worthwhile and potentially important video covering some aspects of the differential diagnosis of COVID-19 infection.

  5. You DO NOT know how many infections there are … because no one knows. But it is alot. People get it, it's not serious (like Tom Hanks' bout that started last week) and never report the infection

  6. 0:22 shouldn't mortality rate be based on closed cases rather than active ones?

    Worldwide as of 19March, 2020:
    – Coronavirus Cases:
    – Deaths:
    – Recovered:
    – Leaving us 10% mortality rate in closed cases.

    In some countries closed cases mortality rate differ:
    – China 4%.
    – Italy 43%.
    – Germany 28%.
    – USA 64% (usa not accurate because closed cases only 339, so no enough data).

  7. This virus chinese is so dangerous. I hope doctor will find out the anti-virus soon. Too many ppl has dead. God bless you, guys.

  8. I see you saw my comment in the February video where I told you “RT” stands for “reverse transcriptase” instead of “real time.” Don’t worry, I’ve made that mistake myself in grad school—That’s why I always remember that!

  9. Can you do a video on the evidence behind potential therapies (e.g. hydroxychloroquine, azithromycin, lopinavir/ritonavir etc.)

  10. loving the content on COVID19. Would u please upload recent pharmacological advances and new drugs tested in your next video

  11. How is the sensitivity of the gold standard calculated? Isn’t it calculated using the Gold std itself?

  12. Antes hacían videos geniales cuando tenían varias traducciones. Ahora veo que ya casi ningún está traducido y que además borraron videos como el de vasculitis o el de coartación de aorta 😔

  13. Excellent man! I'm from Pakistan and your videos are really making difference in my clinical decision making here where resources are limited! keep the good work up!

  14. Although its very sensitive to pick up covid pneumonia, question how good is it to rule of covid infection? As many infected individuals have mild urti symptoms, but still contagious.

  15. It seems to me predator (aliens) has re-shaped to be a super small size to destroy humanity..and a God sent message to challenge the humanity in a manifestation as a virus so that we can improve and learn how to be more in united as the smartest being in planet, rather just say "I am me" ! If we pass this challenge we more likely will also pass the next one, and the next one many not be as easy to combat ! Stop making strange movies, such a bad role model!

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