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

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

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.

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.

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.