Lung ultrasound scan non-inferior to chest X-ray for COVID-19 pneumonia diagnosis

11th February 2022

A lung ultrasound scan is an imaging modality found to be non-inferior to chest X-rays for the diagnosis of COVID-19 pneumonia

The use of a lung ultrasound scan has been observed to be non-inferior to the use of chest X-rays for the diagnosis of patients with COVID-19 viral pneumonia. This was the conclusion of a study by a team from U.O.C. Geriatria, Accettazione Geriatrica e Centro di Ricerca per l’invecchiamento, Ancona, Italy.

The use of a lung ultrasound has been advocated for use in symptomatic medical inpatients with known or suspected COVID-19, to support the diagnosis of pneumonitis. Lung ultrasound enables the identification of early lung involvement during the course of an infection with COVID-19. Nevertheless, the specific role of lung ultrasound in COVID-19 is still evolving and a recent review concluded that the current enthusiasm for lung ultrasound should be directed into strong controlled studies and descriptive analyses towards determining patient outcomes. In addition, ultrasound findings should also be taken in context of all other clinical and radiological.

For the present, retrospective analysis, the authors wanted to demonstrate the usefulness of a lung ultrasound scan in the early diagnosis of COVID-19 positive patients and to compare these results with those of a chest X-ray. Both the ultrasound and chest X-rays were performed on patients during the visit to an emergency department with symptoms suggestive of COVID-19 and there were no exclusions, such as that all patients who received both a lung ultrasound and chest X-ray were included in the analysis. The authors used multiple regression analysis in an effort to identify whether any of the observed changes on the lung ultrasound were significant predictors of both the presence of a positive COVID-19 test result and other clinical outcomes such as the need for intubation and subsequent COVID-19-related mortality.

Lung ultrasound scan findings in relation to COVID-19

A total of 479 patients were included in the retrospective analysis, of whom, 82.6% tested positive for COVID-19 (mean age 66.4 years, 41.2% female). The most common findings on the ultrasound were B-lines (80.17%), irregular pleural lines (59.3%) and small sub-pleural consolidations (55.3%). Moreover, a normal chest X-ray was found in only 18.9% of cases.

When looking at the results of the lung ultrasound, there were some significant differences between COVID-19 positive and negative patients. For example, both pleural effusion (P < 0.001) and B-lines (P < 0.001) were significantly different for the two groups of patients. Using multiple regression analysis, the authors identified how only B-lines and small consolidation were significant predictors of whether a patient tested positive for COVID-19. However, when using adjusted regression models, only consolidations (p < 0.001) on the lung ultrasound scan was significantly associated with a positive COVID-19 test result. Additional analyses also revealed that predictors of the need for orotracheal intubation were ultrasound findings of small consolidation (p = 0.004) and how the presence of ultrasound effusion was a significant predictor of subsequent COVID-19 mortality (p = 0.045), as was X-ray small consolidation (p = 0.043).

Discussing these findings, the authors suggested that their data showed the value of lung ultrasound for the diagnosis of COVID-19 in patients presenting to an emergency department. They added how lung ultrasound was potentially useful for risk stratification of patients given the association of findings with the need for intubation and the mortality risk. They concluded that a lung ultrasound scan was shown to be non-inferior to a chest X-ray and that the ultrasound findings were associated with the presence of a positive test result for COVID-19.

Citation
Caroselli C et al. Early Lung Ultrasound Findings in Patients With COVID‐19 Pneumonia. A Retrospective Multicenter Study of 479 Patients J Ultrasound Med 2022

Lung ultrasound severity index score predicts COVID-19 diagnosis

20th September 2021

A lung ultrasound severity index tool has been shown to be able to identify those with COVID-19 and predict in-hospital mortality.

Although a formal diagnosis of COVID-19 is based on a positive PCR test, it can take up to 24 hours before the result is available. Given that COVID-19 is a respiratory infection, clinicians have often turned to chest imaging with lung ultrasound, X-rays and CT scans, to diagnose the infection prior to confirmation from a PCR test. In fact, a Cochrane review has concluded that the use of a lung ultrasound correctly diagnoses COVID-19 in 86.4% of infected patients.

With the potential value of lung ultrasound as a diagnostic aid in COVID-19, an Italian team from the Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Italy, undertook a prospective, observational study to further examine the value of the imaging modality in those with suspected COVID-19. Patients were those consecutively admitted to the emergency department of a single hospital with suspected COVID-19. Each underwent a standard lung ultrasound examination which included 12 thoracic areas. The team then calculated several different measures with a view to determining whether any of these could be used prognostically for COVID-19. The scores for each thoracic areas were added to calculate a regional lung ultrasound severity score (rLUSS) and a lung ultrasound severity score (LUSS) was calculated by summing all rLUSS values. The number of different ultrasound patterns found in each area defined the regional lung ultrasound heterogeneity score (rLUHS). A regional lung ultrasound severity index (rLUSI) was then calculated as rLUSS/rLUHS for each area. Finally, the team computed a lung ultrasound severity index (LUSI), which was the sum of all the rLUSI scores. The team were interested in whether LUSI, rLUSS or LUHS. The outcomes of interest were a diagnosis of COVID-19 pneumonia and in-hospital mortality and the area under the receiver operating curves (AUROC) analysis was used to determine the relationship between LUSS, LUHS, LUSI and the severity of pneumonia.

Findings
The study included 159 patients with a mean age of 64.6 years (66% male) of whom, 49% had respiratory failure upon admission. For each of the three lung ultrasound measures (i.e., LUSS, LUHS and LUSI), in relation to the differentiation of COVID-19 positive and negative cases, LUSI offered the greatest sensitivity and specificity with an AUROC of 0.72 (95% CI 0.64 – 0.78), giving a sensitivity of 63% and a specificity of 75%. With respect to overall in-hospital mortality, again LUSI scores provided the best AUROC, at 0.81 (95% CI 0.73 – 0.86) providing a sensitivity of 90.9% and a specificity of 65.6%. Finally, when considering only COVID-19 patients, LUSI also gave the highest AUROC, 0.76 (95% CI 0.66 – 0.84) with a sensitivity of 63.1% and a specificity of 90%.

The authors concluded that their newly developed lung ultrasound severity index provided the highest accuracy with respect to COVID-19 diagnosis and prognosis. They also added that a further advantage was how the lung ultrasound could be performed in under 10 minutes, allowing LUSI scores to quickly identify patients at a higher risk of both COVID-19 and mortality and called for future studies to understand LUSI’s role for different clinical goals such as monitoring of treatment or progression.

Citation
Spampinato MD et al. Lung Ultrasound Severity Index: Development and Usefulness in Patients with Suspected SARS-Cov-2 Pneumonia. A Prospective Study. Ultrasound Med Biol 2021