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Purpose: To assess the diagnostic accuracy of traditional chest X-ray (CXR) and digital tomosynthesis (DTS) compared to computed tomography (CT) in detecting pulmonary interstitial changes in patients having recovered from severe COVID-19. Materials and Methods: This was a retrospective observational study, and received local ethics committee approval. Patients suspected of having COVID-19 pneumonia upon emergency department admission between 1 March and 31 August 2020, and who underwent CXR followed by DTS and CT, were considered. Inclusion criteria were as follows: (1) patients with previous SARS-CoV-2 infection proven by a positive RT-PCR on nasopharyngeal swabs performed upon admission to the hospital, and with complete clinical recovery; (2) a diagnosis of SARS-CoV-2-related ARDS, according to the Berlin criteria, during hospitalization; (3) no recent history of other lung disease; and (4) complete imaging follow-up by CXR, DTS, and CT for at least 6 months and up to one year. Analysis of DTS images was carried out independently by two radiologists with 16 and 10 years of experience in chest imaging, respectively. The following findings were evaluated: (1) ground-glass opacities (GGOs); (2) air-space consolidations with or without air bronchogram; (3) reticulations; and (4) linear consolidation. Indicators of diagnostic performance of RX and digital tomosynthesis were calculated using CT as a reference. All data were analyzed using R statistical software (version 4.0.2, 2020). Results: Out of 44 patients initially included, 25 patients (17 M/8 F), with a mean age of 64 years (standard deviation (SD): 12), met the criteria and were included. The overall average numbers of findings confirmed by CT were GGOs in 11 patients, lung consolidations in 8 patients, 7 lung interstitial reticulations, and linear consolidation in 20 patients. DTS showed a significantly higher diagnostic accuracy compared to CXR in recognizing interstitial lung abnormalities—especially GGOs (p = 0.0412) and linear consolidations (p = 0.0009). The average dose for chest X-ray was 0.10 mSv (0.07–0.32), for DTS was 1.03 mSv (0.74–2.00), and for CT scan was 3 mSv. Conclusions: According to our results, DTS possesses a high diagnostic accuracy, compared with CXR, in revealing lung fibrotic changes in patients who have recovered from COVID-19 pneumonia.

This study aimed to describe the chest CT findings in patients with COVID-19 pneumonia who had initially tested negative by NP/OP swab. The final goal is to assist physicians to avoid missed or delayed diagnoses of SARS-CoV-2 infection. Out of 453 patients admitted to the ED and administered chest CT during the study period, 159 had a confirmed diagnosis of COVID-19 pneumonia, according to WHO guidance. In 28 of these confirmed cases (mean age, 64 ± 15 years; male/female, 18/10), the patients initially tested negative by RT-PCR (study group). SARS-CoV-2 infection was confirmed in these patients by repeated NO/OP swab test (nineteen cases) and bronchoalveolar lavage test (nine cases) over a 6-day duration (range, 3---8 days). Unilateral lung involvement was detected in 20 out of the 28 cases. Radiologic abnormalities had peripheral distribution in 27 cases (96%) and involved two or more lobes in four cases (14%). Unilateral GGOs with or without consolidations or crazy paving were significantly more common among patients in the study group compared with those who initially tested positive (19/28 vs. 6/131; p < 0.0001)