OPTIMIZING LUNG ULTRASOUND: THE EFFECT OF DEPTH, GAIN AND FOCAL POSITION ON SONOGRAPHIC B-LINES

Ultrasonographic B-lines are artifacts present in alveolar-interstitial syndromes. We prospectively investigated optimal depth, gain, focal position and transducer type for B-line visualization and image quality. B-Lines were assessed at a single rib interspace with curvilinear and linear transducers. Video clips were acquired by changing parameters: depth (6, 12, 18 and 24 cm for curvilinear transducer, 4 and 8 cm for linear transducer), gain (10%, 50% and 90%) and focal position (at the pleural line or half the scanning depth). Clips were scored for B-lines and image quality. Five hundred sixteen clips were obtained and analyzed. The curvilin-ear transducer improved B-line visualization (63% vs. 37%, p < 0.0001), with higher image quality (3.52 & PLUSMN; 0.71 vs. 3.31 & PLUSMN; 0.86, p = 0.0047) compared with the linear transducer. B-Lines were better visualized at higher gains (curvilinear: gain of 50% vs. 10%, odds ratio = 7.04, 95% confidence interval: 4.03?12.3; gain of 90% vs. 10%, odds ratio = 9.48, 95% confidence interval: 5.28?17.0) and with the focal point at the pleural line (odds ratio = 1.64, 95% confidence interval: 1.02?2.63). Image quality was highest at 50% gain (p = 0.02) but decreased at 90% gain (p < 0.0001) and with the focal point at the pleural line (p < 0.0001). Image quality was highest at depths of 12?18 cm. B-Lines are best visualized using a curvilinear transducer with at least 50% gain and focal position at the pleural line. Gain less than 90% and image depth between 12 and 18 cm improve image quality.(c) 2022 World Federation for Ultrasound in Medicine & Biology. All rights reserved.

Automated summary

In this prospective study, optimal parameters for visualizing ultrasonographic B-lines were investigated, with results showing that using a curvilinear transducer, gain of at least 50%, and focal position at the pleural line can improve B-line visualization and image quality. Increasing gain above 50% and placing the focal point at the pleural line were associated with better B-line visualization, while maintaining image quality.