CT scan effective tool to detect, determine severity of Covid-19 cases: DAK

''CT scan helps in diagnosing and predicting the outcome in Covid-19 patients,'' said DAK President and influenza expert Dr Nisar ul Hassan in a statement here on Saturday afternoon.

''More Covid cases are detected with a CT scan of the chest than through RT-PCR,'' he said.

Dr Hassan said, ''We see many patients who test negative on RT-PCR test, but show CT features consistent with Covid-19 disease.''

''Many infected patients go unreported as only RT-PCR positive cases are reported. We have a large number of patients who test positive through CT, but are not reported,'' he said.

Dr Hassan said RT-PCR, which uses swab for the detection of Covid-19 infection has a sensitivity of 60 per cent-70 per cent. That means more than 30 per cent of positive cases may be missed by the test.

''Another swab test which is now widely used is rapid antigen test. It has a sensitivity of around 50 percent, which raises the possibility of missing more than half of the positive cases,'' he said.

''“Low sensitivity of swab tests implies that many patients with Covid-19 infection may not be identified and consequently are not isolated from healthy population. And these individuals will continue to spread the disease in the community,'' he added.

''Studies have shown that CT has a greater sensitivity ranging from 86 per cent and 98 per cent for detecting positive cases, while having a lower false negative rate than the lab tests,'' Dr Nisar said.

''In a study of 1,014 patients published in the Journal Radiology, researchers in China found that 88 per cent of the patients showed chest CT findings indicative of Covid-19, while RT-PCR test detected only 59 percent of cases. Among those with negative swab test results, 75 percent had positive chest CT findings,'' he said.

The DAK President said not only is CT useful in identifying Covid cases, it also tells us about the severity of the disease.

''That would guide treatment and help reduce the risk of death in Covid patients and save lives,'' he said.