Diagnostic impact of bedside chest X-ray features of 2019 novel coronavirus in the routine admission at the emergency department: case series from Lombardy region

Abstract

Purpose: To evaluate the diagnostic accuracy and the imaging features of routine admission chest X-ray in patients suspected for novel Coronavirus 2019 (SARS-CoV-2) infection.

Method: We retrospectively evaluated clinical and X-ray features in all patients referred to the emergency department for suspected SARS-CoV-2 infection between March 1st and March 13th. A single radiologist with more than 15 years of experience in chest-imaging evaluated the presence and extent of alveolar opacities, reticulations, and/or pleural effusion. The percentage of lung involvement (range <25 % to 75-100 %) was also calculated. We stratified patients in groups according to the time interval between symptoms onset and X-ray imaging (≤ 5 and > 5 days) and according to age (≤ 50 and > 50 years old).

Results: A total of 518 patients were enrolled. Overall 314 patients had negative and 204 had positive RT-PCR results. Lung lesions in patients with SARS-Cov2 pneumonia primarily manifested as alveolar and interstitial opacities and were mainly bilateral (60.8 %). Lung abnormalities were more frequent and more severe by symptom duration and by increasing age. The sensitivity and specificity of chest X-ray at admission in the overall cohort were 57 % (95 % CI = 47-67) and 89 % (83-94), respectively. Sensitivity was higher for patients with symptom onset > 5 days compared to ≤ 5 days (76 % [62-87] vs 37 % [24-52]) and in patients > 50 years old compared to ≤ 50 years (59 % [48-69] vs 47 % [23-72]), at the expense of a slightly lower specificity (68 % [45-86] and 82 % [73-89], respectively).

Conclusions: Overall chest X-ray sensitivity for SARS-CoV-2 pneumonia was 57 %. Sensitivity was higher when symptoms had started more than 5 days before, at the expense of lesser specificity, while slightly higher in older patients in comparison to younger ones.

Keywords: Coronavirus; Infections; Radiography; Tomography; X-ray computed.

Fig. 1

Representative chest radiographic (A) and CT images (B, C, and D) of SARS-CoV-2 pneumonia manifesting as confluent pure alveolar or ground-glass opacities. A. Anteroposterior chest radiograph shows tiny and hazy alveolar opacities in the right middle left upper and middle lung, located in peripheral zones (arrow and arrowheads). B, C, and D. Axial and coronal chest CT images show focal pure ground-glass opacities involving both lungs, in the left upper lobe (arrowheads), and the posterior segment of the right upper lobe (arrow). No pleural effusion or consolidative lesions are evident.

Fig. 2

Representative chest radiograph of SARS-CoV-2 pneumonia in a 67-year-old man, manifesting as an interstitial pattern or alveolar opacities. The anteroposterior chest radiograph shows multiple bilateral and symmetric linear reticular and diffuse alveolar opacities involving all the parts of both lungs (lung involvement 50-75 %), mainly in peripheral zones.

Fig. 3

Representative chest radiographs of SARS-CoV-2 pneumonia in a 71-year-old man manifesting as diffuse alveolar opacities. The anteroposterior chest radiograph reveals an extensive alveolar involvement in the peripheral zone of both lungs, more evident in the middle and inferior part or right lung, and the inferior part of the left lung (lung involvement 50-75 %). Pleural effusion can be appreciated on the left side.

Fig. 4

Representative chest radiographic (A) and CT images (B, C, and D) of SARS-CoV-2 pneumonia manifesting as confluent mixed alveolar or ground-glass opacities and consolidation. A. Anteroposterior chest radiograph shows multifocal alveolar opacities (arrowheads) and patchy peripheral consolidations in both lungs (arrows) B, C and D. Axial chest CT images show mixed ground-glass opacities (arrowheads) and consolidative lesions (arrows) bilaterally in peripheral zones. The confluent lesions are mainly distributed in peripheral areas and some of them contain air-bronchograms.

Fig. 5

Representative chest radiograph of SARS-CoV-2 pneumonia in a 61-year-old man, manifesting mainly as reticular opacities. The anteroposterior chest radiograph shows a few focal linear reticular opacities in the middle part of both lungs located in the central and peripheral areas.