Background To evaluate the diagnostic performance of chest CT in differentiating coronavirus disease 2019 (COVID-19) and non-COVID-19 causes of ground-glass opacities (GGO). Results A total of 80 patients (49 males and 31 females, 46.48 ± 16.09 years) confirmed with COVID-19 by RT-PCR and who underwent chest CT scan within 2 weeks of symptoms, and 100 patients (55 males and 45 females, 48.94 ± 18.97 years) presented with GGO on chest CT were enrolled in the study. Three radiologists reviewed all CT chest exams after removal of all identifying data from the images. They expressed the result as positive or negative for COVID-19 and recorded the other pulmonary CT features with mention of laterality, lobar affection, and distribution pattern. The clinical data and laboratory findings were recorded. Chest CT offered diagnostic accuracy ranging from 59 to 77.2% in differentiating COVID-19- from non-COVID-19-associated GGO with sensitivity from 76.25 to 90% and specificity from 45 to 67%. The specificity was lower when differentiating COVID-19 from non-COVID-19 viral pneumonias (30.5–61.1%) and higher (53.1–70.3%) after exclusion of viral pneumonia from the non-COVID-19 group. Patients with COVID-19 were more likely to have lesions in lower lobes (p = 0.005), peripheral distribution (p < 0.001), isolated ground-glass opacity (p = 0.043), subpleural bands (p = 0.048), reverse halo sign (p = 0.005), and vascular thickening (p = 0.013) but less likely to have pulmonary nodules (p < 0.001), traction bronchiectasis (p = 0.005), pleural effusion (p < 0.001), and lymphadenopathy (p < 0.001). Conclusions Chest CT offered reasonable sensitivity when differentiating COVID-19- from non-COVID-19-associated GGO with low specificity when differentiating COVID-19 from other viral pneumonias and moderate specificity when differentiating COVID-19 from other causes of GGO.

Background and Purpose:The purpose is to provide a comprehensive report describing the clinical and imaging features of Coronavirus disease 2019 (COVID-19)-related acute invasive fungal sinusitis (AIFS) and associated comorbidities. Methods:A retrospective study was conducted on 25 patients (12 males and 13 females, mean age of 53.9±9.1 years). All patients had positive polymerase chain reaction test for COVID-19 and histopathological proof of AIFS. Patients underwent computed tomography (CT) and magnetic resonance examinations to assess sinonasal, orbital, and cranial spread. Results:The most prevalent comorbidity among the study cohort was diabetes mellitus (DM). Twenty-one patients (84%) were diagnosed in the post-COVID-19 period after hospital discharge, with a mean interval of 19.1±9.2 days. Steroid treatment was given to 19 patients (76%). Orbital manifestations were the presenting symptoms in all patients, followed by facial edema, nasal discharge, and neurological symptoms. Sinonasal involvement ranged from mucosal thickening to complete sinus opacification by a predominant isodensity on CT, low T1, and high T2 signal intensity with variable enhancement patterns.Twenty-four patients had a unilateral orbital extension, and 12 patients showed signs of intracranial extension. Bone involvement was detected in 16 patients (64%). Follow-up scans in 18 patients (72%) showed rapid progression of the disease. Eight patients (32%) died, six from neurological complications and two from severe respiratory failure. Conclusion: Steroids, DM, and severe COVID-19 are the major risk factors of AIFS in the post-COVID-19 era. Imaging scans in all patients revealed different sinonasal, facial, orbital features, and intracranial involvement with rapid progression of the findings on follow-up scans.

COVID-19 (coronavirus disease 2019) is a recently emerged pulmonary infection caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2). It started in Wuhan, China, in December 2019 and led to a highly contagious disease. Since then COVID-19 continues to spread, causing exponential morbidity and mortality and threatening economies worldwide. While the primary diagnostic test for COVID-19 is the reverse transcriptase–polymerase chain reaction (RT-PCR) assay, chest CT has proven to be a diagnostic tool of high sensitivity. A variety of conditions demonstrates CT features that are difficult to differentiate from COVID-19 rendering CT to be of low specificity. Radiologists and physicians should be aware of imaging patterns of these conditions to prevent an erroneous diagnosis that could adversely influence management and patients’ outcome. Our purpose is to provide a practical review of the conditions that mimic COVID-19. A brief description of the forementioned clinical conditions with their CT features will be included.

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