Effects of lung ultrasound technique and pleural line depth on in vitro and in vivo measurements of pleural line thickness

Determine the effects of imaging protocol, technique, and pleural line depth on measured pleural line thickness (PLT). Sonograms were performed on a phantom and healthy volunteers. In vitro, pleural line depth, transducer type (5-1 MHz phased array vs. 13-6 MHz linear array), angle of the pleural line relative to the transducer, and distance between the pleural line and focal length were explicitly modified. PLT was measured using electronic calipers. Regression equations described the effects of independent variables on PLT. Factors influencing PLT in vitro were tested in vivo. In vitro (n=250 sonograms): PLT was 3.8 (Standard error= +/-0.24) mm greater when using the phased array compared to the linear transducer (p