ABSTRACT
Background: During the Covid -19 pandemic, there was a need to diagnose the infection at an earlier stage for better treatment and containment of the disease.The standard method of detection was by the real-time reverse-transcription polymerase chain reaction (RT-PCR) tests. However in some cases when the initial PCR tests was negative, HRCT thorax played an important role for earlier detection. Aim: To test the accuracy of HRCT thorax in diagnosing COVID-19 infection in suspected patients with initial negative RT-PCR. Materials and methods: Retrospective analysis of patients with a negative RT PCR but with clinical suspicion of COVID who were referred for HRCT thorax during the initial phase of the disease, were included in the study. HRCT thorax images were categorized as per CORADS scoring system. Those patients with score of 4 or 5 were subjected to repeat RT-PCR test and results were analysed. Results: Total of 52 (33 (63%) males and 19 (37%)females) patients in age group from 36-62yrs,who had clinical suspicion of COVID and underwent HRCT were included.The CT was performed within 10 days of the illness. All these patients had a negative RT-PCR result when CT was performed.22 patients had a CORADS score of 4 and 30 patients had a score of 5. Follow up RT-PCR done within a week after the CT came out to be positive in 45(82.3%) patients. In rest of the 7 (13.4%) patients it was negative. The sensitivity of CT came out to be 84.8% which was statistically significant. Conclusion: HRCT appears to be more accurate in detection of the disease whereas RT-PCR test may produce false-negative results in the initial phase of the disease.