Radiographic findings in 240 patients with COVID-19 pneumonia: time-dependence after the onset of symptoms

Abstract

Objective: To analyze the most frequent radiographic features of COVID-19 pneumonia and assess the effectiveness of chest X-ray (CXR) in detecting pulmonary alterations.

Materials and methods: CXR of 240 symptomatic patients (70% male, mean age 65 ± 16 years), with SARS-CoV-2 infection confirmed by RT-PCR, was retrospectively evaluated. Patients were clustered in four groups based on the number of days between symptom onset and CXR: group A (0-2 days), 49 patients; group B (3-5), 75 patients; group C (6-9), 85 patients; and group D (> 9), 31 patients. Alteration's type (reticular/ground-glass opacity (GGO)/consolidation) and distribution (bilateral/unilateral, upper/middle/lower fields, peripheral/central) were noted. Statistical significance was tested using chi-square test.

Results: Among 240 patients who underwent CXR, 180 (75%) showed alterations (group A, 63.3%; group B, 72%; group C, 81.2%; group D, 83.9%). GGO was observed in 124/180 patients (68.8%), reticular alteration in 113/180 (62.7%), and consolidation in 71/180 (39.4%). Consolidation was significantly less frequent (p < 0.01). Distribution among groups was as follows: reticular alteration (group A, 70.9%; group B, 72.2%; group C, 57.9%; group D, 46.1%), GGO (group A, 67.7%; group B, 62.9%; group C, 71%; group D, 76.9%), and consolidation (group A, 35.5%; group B, 31.4%; group C, 47.8%; group D, 38.5%). Alterations were bilateral in 73.3%. Upper, middle, and lower fields were involved in 36.7%, 79.4%, and 87.8%, respectively. Lesions were peripheral in 49.4%, central in 11.1%, or both in 39.4%. Upper fields and central zones were significantly less involved (p < 0.01).

Conclusions: The most frequent lesions in COVID-19 patients were GGO (intermediate/late phase) and reticular alteration (early phase) while consolidation gradually increased over time. The most frequent distribution was bilateral, peripheral, and with middle/lower predominance. Overall rate of negative CXR was 25%, which progressively decreased over time.

Key points: • The predominant lung changes were GGO and reticular alteration, while consolidation was less frequent. • The typical distribution pattern was bilateral, peripheral, or both peripheral and central and involved predominantly the lower and middle fields. • Chest radiography showed lung abnormalities in 75% of patients with confirmed SARS-CoV-2 infection, range varied from 63.3 to 83.9%, respectively, at 0-2 days and > 9 days from the onset of symptoms.

Keywords: COVID-19; Pneumonia; Radiography; Severe acute respiratory syndrome coronavirus 2; Thorax.

Fig. 1

The three main alterations on chest radiography (upper line) and the corresponding findings on chest CT (lower line). Left: diffuse reticular alteration (arrows). The corresponding CT shows diffuse increased lung attenuation and interlobular septal thickening (arrows). Middle: peripheral ground-glass opacities (arrows). Right: extensive consolidations (arrows). The corresponding CT shows predominant consolidative alterations (arrows)

Fig. 2

a Group A, usual distribution. Chest radiography of a 78-year-old man, acquired within the first 2 days since the onset of symptoms, showing bilateral reticular alteration in the middle and lower fields (arrows). b Group B, usual distribution. Chest radiography of a 79-year-old woman, acquired within 3–5 days since the onset of symptoms, showing bilateral peripheral ground-glass opacities (arrows) and faint reticular alteration in the right lower field. c Group C, usual distribution. Chest radiography of a 60-year-old woman, acquired within 6–9 days since the onset of symptoms, showing bilateral and symmetrical mixed patterns with ground-glass opacification, patchy consolidations (arrows); reticular alteration in the right lower and middle fields. d Group D, usual distribution. Chest radiography of a 61-year-old woman, acquired after 10 days since the onset of symptoms, showing bilateral and symmetrical extensive consolidations (arrows)

Fig. 3

The trend of the radiographic alterations in the different groups

Fig. 4

The horizontal distribution (orange) and the craniocaudal distribution (green) of the alterations in the different groups