Role of HRCT Chest in Diagnosing Covid-19 Disease in Initially RT-PCR Negative Patients

Objective: To analyze CTSS score in clinically symptomatic COVID-19 patients having initial negative RT-PCR report. Design of the Study: It's a retrospective cross sectional descriptive study. Study Settings: This study was carried out at Radiology Department, CMH Lahore from July to December 2021. Material and Methods: A total of 1000 patients presented with suspected clinical symptoms of covid-19. 770 were male patients (average of 52 +/- 15yrs) and 230 were female patients (49 +/- 15 years). Out of which 235 (23.5%) patients had initial negative PCR report & 765 patients had initial PCR positive report. 235 initial PCR negative patients got positive PCR report on subsequent repeat testing. All the patients underwent HRCT chest. Results of the Study: CTSS score of 765 PCR positive patients was determined as 545 (71.2%) having mild to moderate disease (<19.5 CTSS) and 220 (28.7%) as having severe disease (>19.5 CTSS).CTSS score of 235 PCR negative patients was determined on HRCT chest and classified as 210 (89.3%) having mild to moderate disease (<19.5 CTSS) and 25 (10.6%) as having severe disease (>19.5 CTSS). CO-RADS scoring were done and HRCT pattern analyzed in all the patients according to the standard protocol. Multivariate analysis was performed and showed significant correlation between CTSS score and initial PCR negative patients. Sensitivity and specificity of CT chest in determining covid-19 findings was 89.3% and 28.7%.PPV was 89.8% and NPV was 27.8%. Conclusion: HRCT with CTSS scoring is an important tool for diagnosis of COVID-19 infection despite initial negative PCR, having sensitivity and specificity of 89.3% and 28.7% respectively. Timely identification and isolation of COVID-19 patients is helpful in preventing the spread of infection and also aid in prompt symptomatic management.