Analysis of high-resolution computed tomography chest in interferon gamma release assay negative COVID-19 patients: From a COVID hospital of Odisha, India

ABSTRACT

Background: Atypical category of COVID-19 could not be differentiated from tuberculosis (TB) in high-resolution computed tomography (HRCT) of the chest because of similar imaging features. This study aims to distinguish between the HRCT features of TB and atypical COVID-19. Methodology: Interferon-gamma release assay (IGRA) was performed in all the 54 COVID-positive patients, showing atypical COVID features that are suspicious of TB on the HRCT chest. Atypical imaging features such as a tree in bud nodules, patchy consolidations, cavitation with surrounding consolidation, discrete nodules, mediastinal lymphadenopathy, and pleural effusion were analyzed in 50 IGRA-negative patients. Results: We found trees in bud nodules (93%) and consolidations (56%) involving predominantly lower lobes, i.e., superior and posterobasal segments. Discrete nodules and cavitation with surrounding consolidation were seen involving predominantly upper lobes (78 and 57% cases, respectively), i.e., apicoposterior and lingular segments of the left upper lobe. The maximum number (67%) of right paratracheal enlarged nodes and bilateral pleural effusions (71%) were found in IGRA-negative COVID-19 patients. Conclusions: It is not always possible to differentiate features of atypical COVID-19 from TB based on HRCT chest alone because of similar appearances and distribution of tree in bud nodules, consolidation, cavitation, and lymphadenopathy in HRCT chest. Since both bilateral and unilateral pleural effusions may be seen in TB, it is impossible to differentiate COVID-19 from TB based on pleural effusion. Therefore, exclusion of TB will need supportive, relevant laboratory investigations (Sputum acid fast bacilli, cartridge-based nucleic acid amplification test, and IGRA) for appropriate diagnosis and management.