Chest x-ray in the COVID-19 pandemic: Radiologists’ real-world reader performance

Andrea Cozzi, Simone Schiaffino, Francesco Arpaia, Gianmarco Della Pepa, Stefania Tritella, Pietro Bertolotti, Laura Menicagli, Cristian Giuseppe Monaco, Luca Alessandro Carbonaro, Riccardo Spairani, Bijan Babaei Paskeh, Francesco Sardanelli

Research output: Contribution to journalArticlepeer-review


Purpose: To report real-world diagnostic performance of chest x-ray (CXR) readings during the COVID-19 pandemic. Methods: In this retrospective observational study we enrolled all patients presenting to the emergency department of a Milan-based university hospital from February 24th to April 8th 2020 who underwent nasopharyngeal swab for reverse transcriptase-polymerase chain reaction (RT-PCR) and anteroposterior bedside CXR within 12 h. A composite reference standard combining RT-PCR results with phone-call-based anamnesis was obtained. Radiologists were grouped by CXR reading experience (Group-1, >10 years; Group-2, <10 years), diagnostic performance indexes were calculated for each radiologist and for the two groups. Results: Group-1 read 435 CXRs (77.0 % disease prevalence): sensitivity was 89.0 %, specificity 66.0 %, accuracy 83.7 %. Group-2 read 100 CXRs (73.0 % prevalence): sensitivity was 89.0 %, specificity 40.7 %, accuracy 76.0 %. During the first half of the outbreak (195 CXRs, 66.7 % disease prevalence), overall sensitivity was 80.8 %, specificity 67.7 %, accuracy 76.4 %, Group-1 sensitivity being similar to Group-2 (80.6 % versus 81.5 %, respectively) but higher specificity (74.0 % versus 46.7 %) and accuracy (78.4 % versus 69.0 %). During the second half (340 CXRs, 81.8 % prevalence), overall sensitivity increased to 92.8 %, specificity dropped to 53.2 %, accuracy increased to 85.6 %, this pattern mirrored in both groups, with decreased specificity (Group-1, 58.0 %; Group-2, 33.3 %) but increased sensitivity (92.7 % and 93.5 %) and accuracy (86.5 % and 81.0 %, respectively). Conclusions: Real-world CXR diagnostic performance during the COVID-19 pandemic showed overall high sensitivity with higher specificity for more experienced radiologists. The increase in accuracy over time strengthens CXR role as a first line examination in suspected COVID-19 patients.

Original languageEnglish
Article number109272
JournalEuropean Journal of Radiology
Publication statusPublished - Nov 2020


  • COVID-19
  • Pneumonia, viral
  • Radiography, thoracic
  • Severe acute respiratory syndrome coronavirus 2

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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