Convex Versus Linear Transducer In COVID-19 Lung Ultrasound: A Prospective Comparative Cohort

Background and purposeIt is currently unknown whether ultrasound transducer differences influence COVID-19 pneumonia images. Our aim was to describe and compare the results obtained using convex and linear transducers for image acquisition in COVID-19 lung ultrasound. MethodsThis is a single centre prospective cohort study, comparing convex and linear probes in 16 adult patients with SARS-CoV-2 pneumonia. We analysed 12 lung-fields and described the presence of pleural thickening, pleural irregularity, B-lines, >3 B-lines, coalescing B-lines, subpleural consolidation, pulmonary consolidation and pleural effusion in each of these fields and with both transducers. In addition, the Lung Ultrasound Score (LUS) was calculated for every patient using the two transducers. ResultThe mean LUS difference between both transducers was statistically significant in the right lower lateral, upper and lower posterior quadrants; as well as in the left lower anterior and upper posterior quadrants. Furthermore, mean total LUS difference was also statistically significant (15.81 convex vs. 10.81 linear; p = 0.001). The most frequently described findings with the convex transducer compared to the linear transducer were pleural irregularity, pleural thickening, >3 B-lines, coalescing B-lines and subpleural consolidation. On the opposite side, pleural effusion was more frequently described with the linear probe. ConclusionsLung ultrasound in COVID-19 pneumonia is a transducer-dependent technique. This difference is more pronounced in posterior quadrants and in the cardiac area. Although both linear and convex transducers are suitable for the evaluation of COVID-19 pneumonia, the convex probe provides more information than the linear probe if only one of the two is accessible.