The best explanation of the radiographic findings in COVID-19 is in this osmosis video. I highly recommend everyone to watch it.
I just highlighted some slides, which I thought were super important.
Chest CT can identify COVID-19 in individuals before they become symptomatic. In these individuals, ground glass opacities were seen, mostly along the peripheral lung. https://www.thelancet.com/action/showPdf?pii=S1473-3099%2820%2930086-4
In CT, we see ground glass opacities which then progress to consolidations and crazy paving patterns as lung air sacs fill with fluid.
At present, the American College of Radiology does not recommend radiographic imaging for initial diagnostic testing of suspected COVID-19 infection. See https://www.acr.org/Advocacy-and-Economics/ACR-Position-Statements/Recommendations-for-Chest-Radiography-and-CT-for-Suspected-COVID19-Infection for more details. The CDC recommends collecting and testing specimens from the upper and lower respiratory tract.
The ACR says that the findings on chest imaging are not specific and overlap with other infections, and it is challenging to distinguish this disease from the flu.
The ACR states that CT should be used sparingly and reserved for hospitalized, symptomatic patients with appropriate indications. They are additionally concerned about the constant environmental cleaning and decontamination of rooms from patients with COVID-19 infection.
This is quite different from the China experience, where the Chinese aggressively imaged everyone. China also built two hospitals in two weeks. China has reported its first day with no new cases of COVID-19 on March 19, 2020, and I wonder if we should be following their example.
The Chinese recommendations are listed and compiled by Jack Ma here: https://covid-19.alibabacloud.com/.
Specifically, they write that:
Thoracic imaging is of great value in the diagnosis of COVID-19, monitoring of therapeutic efficacy, and patient discharge assessment. A high-resolution CT is highly preferable. Portable chest X-rays are helpful for critically ill patients who are immobile. CT for baseline evaluation of patients with COVID-19 is usually performed on the day of admission, or if ideal therapeutic efficacy is not reached, it can be re-performed after 2 to 3 days. If symptoms are stable or improved after treatment, the chest CT scan can be reviewed after 5 to 7 days. Daily routine portable chest X-rays are recommended for critically ill patients.