Overview
Coronaviruses are a family of viruses that can cause illnesses such as the common cold, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). In 2019, a new coronavirus was identified as the cause of a disease outbreak that originated in China.
The virus is now known as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease it causes is called coronavirus disease 2019 (COVID-19). In March 2020, the World Health Organization (WHO) declared the COVID-19 outbreak a pandemic.
Public health groups, including the U.S. Centers for Disease Control and Prevention (CDC) and WHO, are monitoring the pandemic and posting updates on their websites. These groups have also issued recommendations for preventing and treating the illness.
Symptoms
Signs and symptoms of coronavirus disease 2019 (COVID-19) may appear two to 14 days after exposure. This time after exposure and before having symptoms is called the incubation period. Common signs and symptoms can include:
- Fever
- Cough
- Tiredness
Early symptoms of COVID-19 may include a loss of taste or smell.
Other symptoms can include:
- Shortness of breath or difficulty breathing
- Muscle aches
- Chills
- Sore throat
- Runny nose
- Headache
- Chest pain
- Pink eye (conjunctivitis)
- Nausea
- Vomiting
People who are older have a higher risk of serious illness from COVID-19, and the risk increases with age. People who have existing medical conditions also may have a higher risk of serious illness.
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ROLE OF RADIOLOGY IN COVID
Definitive diagnosis of coronavirus disease 2019 (COVID-19) is usually made by using a reverse transcription-polymerase chain reaction (RT-PCR) assay, which performs accurately in a laboratory setting. However, reported sensitivities in clinical practice range from 42% to 83% and depend on symptom duration, viral load, and test sample quality. Cases are increasingly reported in which the assay yielded a positive result only after multiple negative results in patients with typical clinical and imaging signs of COVID-19. Also, RT-PCR takes hours, or even days, before the results are available, putting strain on the holding units where patients are kept before being sent to a normal or COVID-19 ward. Increasingly, situations arise in which RT-PCR tests are scarce and cannot be used for every patient.In light of this, the role of chest CT in patients suspected of having COVID-19 is constantly evolving with modest scientific evidence but substantial differences in opinion on when and how the technique should be used for clinical work-up or treatment decisions.
The primary findings on CT in adults are:
ground-glass opacities (GGO): bilateral, subpleural, peripheral
crazy paving appearance (GGOs and inter-/intra-lobular septal thickening)
air space consolidation
bronchovascular thickening in the lesion
traction bronchiectasis
The ground-glass and/or consolidative opacities are usually bilateral, peripheral, and basal in distribution
ATYPICAL FINDINGS
These findings only seen in a small minority of patients should raise concern for super-added bacterial pneumonia or other diagnoses :
mediastinal lymphadenopathy
pleural effusions: may occur as a complication of COVID-19
multiple tiny pulmonary nodules (unlike many other types of viral pneumonia)
tree-in-bud
pneumothorax
cavitation
atoll sign
pneumomediastinum
CO-RADS, the COVID-19 Reporting and Data System
CO-RADS provides a level of suspicion for pulmonary involvement of COVID-19 based on the features seen at unenhanced chest CT. The level of suspicion increases from very low (CO-RADS category 1) to very high (CO-RADS category 5). Two additional categories encode a technically insufficient examination (CO-RADS category 0) and RT-PCR–proven severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection at the time of examination (CO-RADS category 6).
It should be noted that CO-RADS is a CT-based system that is used to assess the suspicion of pulmonary involvement in COVID-19. The actual interpretation of whether a patient has COVID-19 needs to include other data, such as laboratory test results, clinical findings, and type and duration of symptoms. At present, the reference standard for diagnosing COVID-19 remains positive RT-PCR results.
The CT severity score index is a scoring system used to assess the lung changes and involvement by COVID-19 based on approximate estimation of pulmonary involved areas. Each of the five lung lobes has been visually scored and given a score from 1 to 5 :
- 1: representing less than 5% lobar involvement.
- 2: 5–25% lobar involvement.
- 3: 26–50% lobar involvement
- 4: 51–75% lobar involvement
- 5: > 75% lobar involvement..
Then, the final score will be the summation of individual lobar scores and will be out of 25 (total score)
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