How to assess severity of COVID-19 based on CT score

ROLE OF CHEST CT IN DIAGNOSTIC DECISION MAKING

Chest CT(Computed Tomography) is performed to detect any abnormalities in the lung or respiratory tract. Generally, COVID-19 symptomatic patients go for rapid or RT PCR tests to confirm COVID-19 infection, but many doctors refer to Chest CT for more accurate results. It is because of the accuracy and helps for a better diagnosis of the condition.

In the CT report, you are given a CORDS number, CT severity score, CT findings, etc. People are not aware of the severity of their respective scores. Everyone needs to know about scores and their severity level.

During a CT scan, you are sent into a tunnel-like machine, while the inside of the machine rotates and takes a series of x-rays from different angles. These pictures are then sent to a computer, where they are combined to create images of slices of the part taken.

A radiologist studies the scan report assesses the percentage of infection in each lung lobe, and gives a total CT severity score.

 

 

LOBES OF LUNG

Lobes are five distinct anatomical compartments.

The right lung has three lobes-Superior, Middle, Inferior

Whereas the left lung has two lobes-Superior and inferior.

 

 

LOBAR SCORING

According to the lobar scoring system, score calculation is done based on the involvement of each lobe.

If less than 5% of the lobe is involved -1 point

If  5-25% of the lobe is involved -2 points

If 25-50% of the lobe is involved -3 points

If 50-60% of the lobe is involved, -4 points

If more than 70% of the lobe is involved -5 points

In this way, all five lobes are given a total score out of 25. This is the CT severity score.

 

 

INTERPRETATION

If the total CT severity score is below 8/25 - it suggests MILD COVID

                                                9/25-15/25- suggests MODERATE COVID

                                       more than 15/25- suggests SEVERE COVID

 

 

CORADS CLASSIFICATION

CORAD score is a CT-based system that is used to assess the suspicion of pulmonary involvement in COVID-19. The following table provides information about the CORDS scores given by the doctor in the scan report.

CO-RADS 0                inadequate scans technically insufficient for assigning a score

CO-RADS 1                Very low                    normal lung is present, no lung involvement in infections

CO-RADS 2                  Low                          Abnormalities consistent with infections other than COVID-19

CO-RADS 3                Intermediate             Unclear whether COVID  is present or not

CO-RADS 4                   High                       Abnormalities suspicious for COVID

CO-RADS 5                Very high                  Typical COVID-19 features

CO-RADS 6                Proven                      RT PCR positive for SARS CoV-2

 

 

 

CT severity score is only given for CO-RADS 5 and 6.

In this way, you can assess the severity of COVID-19 and interpret the values given in your CT scan report. CT Thorax has greater sensitivity (86%-98%) and lowers the false-negative rate.

The 25 point CT severity score correlates well with COVID-19 disease clinical severity. It is high time; everyone should have a minimum basic knowledge about the tests performed and how they are assessed. Awareness about vaccines, precautions, tests performed, medicines, etc., is necessary. Immediate action should be taken when you suspect COVID-19 symptoms. Consult a doctor and get treated.

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