[Dandelion clock-like sign on CT for diagnose of COVID-19]

Abstract

Objective: To explore the value of the "dandelion clock-like" sign on chest CT for diagnosis of SARS-CoV-2-associated pneumonia.

Methods: This retrospective analysis was conducted based on the data of 119 cases from the Department of Fever and the Department of Infection undergoing chest high-resolution CT examinations in Sanshui District People's Hospital between January, 24 and February 10, 2020. The cases with no abnormality on chest CT were excluded. Twenty-three patients were diagnosed to have pneumonia, including 9 with SARS-CoV-2-associated pneumonia and 14 with other types of pneumonia. We comparatively analyzed the CT signs, location of the lesions and the dandelion clock-like sign among different types of pneumonia.

Results: Among the 23 patients with pneumonia, 9 (39.1%) had common or severe SARS-CoV-2- associated pneumonia with a positive epidemiological history and corresponding respiratory symptoms. Seven of the SARSCoV-2-associated pneumonia patients had multiple lesions in bilateral lungs, compromising mainly the lung field and the subpleural area and showing patchy, lumpy, and umbrella-shaped ground glass opacity, often accompanied by pulmonary vascular thickening and increased microvessels, interlobular septal thickening and fibrosis and lined with grid-like and small-bubble-like "crazy-paving" patterns. The dandelion clock-like sign was found in all the 9 patients with SARSCoV-2-associated pneumonia, with a total of 46 lesions (60.5%, 76 total lesions); 9 of the lesions presented with a "dandelion clek-like" sign and 37 with a "dandelion seed sign". These signs were not found in the 14 patients with other types of pneumonia.

Conclusions: The dandelion clock-like sign is a common and characteristic chest CT finding in patients with SARS-CoV-2-associated pneumonia, and can help to distinguish SARS-CoV-2-associated pneumonia from other types of pneumonia.

Keywords: computed tomography; dandelion clock-like; ground-glass opacity; novel coronavirus; novel coronavirus pneumonia.

1

NCP患者典型的“蒲公英果实征” Typical "dandelion clock-like" sign on chest CT in patients with SARS-CoV-2-associated pneumonia. A: Chest CT finding of dandelion clew-like sign in a 22-year-old female patient. The pulmonary blood vessel (arrow) forms the "flower stem" and the thickened blood vessels or the grid-like interstitial tissues (arrow) form the "seeds"; B: Image of a dandelion clock; C: Dandelion seed sign in a 38-year-old female patient. The subpleural fusion of the lesions gives rise to the dandelion seed sign (arrow), with the pulmonary vessels (arrow) as the "seed stem", with the "seeds" carried by wind (respiratory tract) to fall below the pleura; D: Coronal reconstruction image showing dandelion seed sign (arrow) in a 38-year-old male patient, with the pulmonary blood vessel (arrow) as the seed stem; E: Dandelion flower seeds.

2

NCP患者CT图像 Chest CT images of 2 patients with SARS-CoV-2-associated pneumonia. A, B: Bilateral subpleural multiple ground glass opacity with solid components (arrows) and "dandelion clew-like" sign (arrows in A) in a 58-year-old female patient. C, D: Bilateral subpleural multiple ground glass opacity (arrows) and dandelion seed sign (triangle) in a 48-year-old female patient (arrows indicate the pulmonary vessels).

3

其他类型肺炎CT图像 CT images of other types of pneumonia. A, B: Influenza viral pneumonia in a 21-year-old female patient. Four days later, CT reexamination showed ground glass opacity in the dorsal segment of the lower lobe of the right lung (arrow) with less solid components. SARS-CoV-2 nucleic acid test was negative for several times, and immunofluorescence test showed positivity for influenza B virus. C: Bacterial pneumonia showing large flaky consolidation of bilateral lungs with air bronchogram.