May 30, 2020
Reviewed by Zeina A. Kanafani, M.D., MS, FIDSA
December 2019 marked the beginning of the COVID-19 pandemic, which is caused by SARS-CoV-2. The clinical manifestations of the infection are variable and range from a mild infection with no or little respiratory symptoms to a severe lower respiratory tract infection. In a recent Lancet Infectious Diseases study, the authors provide a description of the radiological manifestations in 81 patients with COVID-19 pneumonia from Wuhan, China, the original epicenter of the pandemic.
The cases originated from two hospitals and all were confirmed by RT-PCR analysis of throat swab specimens. Patients were divided into four groups: Group 1 consisted of subclinical cases in which computed tomography (CT) scans were done before onset of symptoms; Group 2 included patients with CT scans done ≤ 1 week after symptom onset; Group 3, those with CT scans done > 1-2 weeks after symptom onset; and Group 4, those with CT scans done > 2-3 weeks after symptom onset.
Eighty-one patients were included in the study: 15 (19%) in Group 1, 21 (26%) in Group 2, 30 (37%) in Group 3, and 15 (19%) in Group 4. There were abnormal CT findings in all patients, with the right lower lobe more likely to be involved (27% of all affected segments in all patients). Patients in Groups 2-4 had, on average, more segments involved compared to those in Group 1 (P < 0.0001). There was bilateral lung involvement in 79% of patients. Imaging patterns included ground glass opacity (65%), ill-defined margins (81%), smooth or irregular interlobular septal thickening (35%), air bronchogram (47%), crazy paving pattern (10%), and thickening of the adjacent pleura (32%). Ground glass opacities were the predominant pattern encountered in 93% of patients in Group 1, and then decreasing in Group 2 (81%), Group 3 (57%), and Group 4 (33%). As the disease progressed, other patterns (reticular, consolidations, and mixed) became more common.
Seventy percent of patients had follow-up CT done, with four types of evolution: Type 1, showing initial progression to peak level followed by radiographic improvement (46%), with 92% of patients discharged; Type 2, showing radiographic deterioration (32%), with 11% of patients dying; Type 3, showing radiographic improvement (14%), with 63% of patients discharged; and Type 4, showing unchanged radiographic appearance (9%), with all patients remaining in the hospital at the end of the follow-up period.
The authors conclude that even asymptomatic patients with COVID-19 will have abnormalities on CT scan. The predominant findings associated with this infection are ground glass opacities with ill-defined margins. Radiographic deterioration seems to be associated with a poor outcome.