- ISSN: 1999-7086
- EISSN: 1999-7094
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oa Analysis of reversed halo and bullseye signs in patients with COVID-19 pneumonia on CT scan
- Source: Journal of Emergency Medicine, Trauma and Acute Care, Volume 2022, Issue 3 - The International and Scientific Conference of Alnahrain College of Medicine and Colleges of Medicine in Iraq confronting COVID-19 Pandemic (ISMC-2022) , Jul 2022,
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- 06 April 2022
- 03 May 2022
- 06 June 2022
Abstract
Background: The reversed halo sign described in the pre-COVID era in certain pulmonary pathologies, most notably cryptogenic organizing pneumonia, has been reported with varying frequency in coronavirus disease 2019 (COVID-19) pneumonia caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, we aimed to analyze the pattern of the reversed halo sign and its variant, the bullseye sign in patients with COVID-19 pneumonia. Methods: In this study, a retrospective analysis of chest CT scans performed in the CT unit of Al-Imammain Al-Kadhymain Medical City for a three-month duration (from June to August 2020) was done. Of the 490 CT scans performed for patients with COVID-19, 330 had signs of COVID-19 pneumonia. These were evaluated for the presence of reversed halo or bullseye sign, and only obvious signs detected in at least two orthogonal planes were included. The number of these signs in each scan was documented, and an analysis of individual signs was performed. The following features were recorded; size, location, shape, and type of the peripheral rim (whether complete or incomplete, thin or thick, distinct or hazy, and uniform or non-uniform). Results: A total of 26 CT exams were included in the study. The average age of the patients was 44.85 ± 20.14 years, and the total number of typical reversed halo or bullseye sign lesions was 63. The rate of reversed halo/bullseye sign in this study was 7.88%. In 15 patients, the typical sign of reversed halo was seen, the bullseye sign was noted in eight patients, and three patients had both the reversed halo and bullseye signs. Nearly all the patients had other CT findings of COVID-19 pneumonia, except one with only a solitary bullseye lesion. The number of lesions ranged from one to nine with the average number of lesions per patient being 2.42. The mean size of the lesions was 3.39 cm with a size range 1–8.5 cm. Lesions were located in the periphery of the lung in most patients (93.7%). Basal predominance was seen in 76.19% patients, located in the lower lobes. A higher percent of bullseye lesions located in the upper and right middle lobes was observed (n = 12/23) than the typical reversed halo lesions (n = 3/40). Most lesions were oval (52.38%) or rounded (48.86%). In 77.78%, the peripheral rim was incomplete. The thickness of the peripheral rim was variable ranging from 2–19 mm. Most lesions (92.06%) exhibited a thin peripheral rim ( < 1 cm). The rim was clearly distinct in 53.97% of lesions. It was non-uniform in thickness in most cases (95.24%). Conclusion: The reversed halo sign is not infrequent among CT findings in patients with COVID-19 pneumonia. The typical reversed halo sign is more common than its variant, the bullseye sign. Variability in morphology and size does exist. In patients with COVID-19, these lesions exhibit thin, incomplete peripheral rims and are multiple in most cases.
