Descriptive analysis of a comparison between lung ultrasound and chest radiography in patients suspected of COVID-19

Abstract

Background: Lung ultrasound (LUS) and chest radiography (CXR) are the most used chest imaging tools in the early diagnosis of COVID-19 associated pneumonia. However, the relationship between LUS and CXR is not clearly defined. The aim of our study was to describe the comparison between LUS interpretation and CXR readings in the first approach to patients suspected of COVID-19.

Methods: In the time of the first COVID-19 pandemic surge, we prospectively evaluated adult patients presenting to an emergency department complaining of symptoms raising suspicion of COVID-19. Patients were studied by LUS and only those performing also CXR were analyzed. All the patients performed viral reverse transcriptase-polymerase chain reaction (RT-PCR). LUS studies were classified in 4 categories of probabilities, based on the presence of typical or alternative signs of COVID-19-associated interstitial pneumonia. Accordingly, the CXR readings were retrospectively adapted by 2 experts in 4 categories following the standard language that describes the computed tomography (CT) findings. Patients were divided in two groups, based on the agreement of the LUS and CXR categories. Results were also compared to RT-PCR and, when available, to CT studies.

Results: We analyzed 139 cases (55 women, mean age 59.1 ± 15.5 years old). The LUS vs CXR results disagreed in 60 (43.2%) cases. RT-PCR was positive in 88 (63.3%) cases. In 45 cases, a CT scan was also performed and only 4 disagreed with LUS interpretation versus 24 in the comparison between CT and CXR. In 18 cases, LUS detected signs of COVID-19 pneumonia (high and intermediate probabilities) while CXR reading was negative; in 14 of these cases, a CT scan or a RT-PCR-positive result confirmed the LUS interpretation. In 6 cases, LUS detected signs of alternative diagnoses to COVID-19 pneumonia while CXR was negative; in 4 of these cases, CT scan confirmed atypical findings.

Conclusion: Our study demonstrated a strong disagreement between LUS interpretation and CXR reading in the early approach to patients suspected of COVID-19. Comparison with CT studies and RT-PCR results seems to confirm the superiority of LUS over a second retrospective reading of CXR.

Fig. 1

The flow chart of patients enrolled in the study

Fig. 2

The case of an otherwise healthy 46-year-old man complaining of fever, cough and dyspnea for 7 days (severe phenotype). LUS and CXR were in agreement. LUS showed a high probability pattern for COVID-19 pneumonia. The LUS scans reported in the bottom panel show a patchy and bilateral distribution of clusters of B-lines and light beam (1, 2, 4), alternating with normal A-lines pattern (3). CXR in the upper right panel was read typical for the presence of bilateral GGO and reticular alterations. The corresponding CT scan in the upper left panel shows multiple GGO alterations that were considered typical appearance. The points numbered in the CT image correspond to the 4 LUS scans. RT-PCR was positive. Unfortunately, the patient died of COVID-19 after 20 days from admission. LUS   Lung Ultrasound, CXR  Chest Radiography, COVID-19  Corona Virus Disease 2019, GGO   Ground Glass Opacity, CT   Computed Tomography, RT-PCR  Reverse Transcriptase-Polymerase Chain Reaction

Fig. 3

The case of an otherwise healthy 77-year-old man complaining of fever and cough for 7 days (mild phenotype). LUS and CXR were in disagreement. LUS showed a high probability pattern for COVID-19 pneumonia. The LUS scans reported in the bottom show the patchy and bilateral distribution of clusters of B-lines and light beam (1, 2, 4) with some irregularity of the pleural line (1, 4), alternating with normal A-lines pattern (3). CXR in the upper right panel was read negative. Corresponding CT scan in the upper left panel shows bilateral GGO and was considered typical appearance. The points numbered in the CT image correspond to the 4 LUS scans. Viral RT-PCR was positive. LUS   Lung Ultrasound, CXR  Chest Radiography, COVID-19  Corona Virus Disease 2019, GGO   Ground Glass Opacity, CT   Computed Tomography, RT-PCR  Reverse Transcriptase-Polymerase Chain Reaction

Fig. 4

The case of an otherwise healthy 44-year-old woman complaining of malaise, anosmia, fever and cough for 4 days (mild phenotype). LUS and CXR were in disagreement. LUS showed an intermediate probability pattern for COVID-19 pneumonia. One of the LUS scans reported in the bottom shows an isolated area with B-lines, light beam and a peripheral consolidation (3). The other LUS scans show A-lines (1, 2, 4). CXR in the upper right panel was read negative. Corresponding CT scan in the upper left panel shows a limited peripheral area with GGO and a consolidation and was considered indeterminate appearance. The points numbered in the CT scan correspond to the 4 LUS scans. Viral RT-PCR was positive. LUS   Lung Ultrasound, CXR  Chest Radiography, COVID-19  Corona Virus Disease 2019, GGO   Ground Glass Opacity, CT   Computed Tomography, RT-PCR  Reverse Transcriptase-Polymerase Chain Reaction

Fig. 5

The case of a 48-year-old woman with a history of HCV related chronic hepatitis, complaining of fever and cough for two weeks (mild phenotype). LUS and CXR were in disagreement. LUS showed an alternative pattern to COVID-19 pneumonia. One of the LUS scans reported in the bottom shows a large lobar isolated consolidation with dynamic air bronchograms (3). The other LUS scans show A-lines (1, 2, 4). CXR in the upper right panel was read typical of COVID-19 pneumonia due to bilateral reticular alterations and GGO. Corresponding CT scan in the upper left panel shows a large consolidation with air bronchograms without significant GGO alterations and was confirmed atypical appearance (bacterial pneumonia) The points numbered in the CT scan correspond to the 4 LUS scans. Viral RT-PCR was negative. The patient recovered after antibiotic treatment. LUS   Lung Ultrasound, CXR  Chest Radiography, COVID-19  Corona Virus Disease 2019, GGO   Ground Glass Opacity, CT   Computed Tomography, RT-PCR  Reverse Transcriptase-Polymerase Chain Reaction