Table 1. Table of possible influencing factors on BLA visualization. During a pilot study we found the following parameters influencing the detection, number, size and shape of BLA (personal observation of Christoph Dietrich and his group).

Manufacturer

Imaging techniques, e.g., tissue harmonic imaging (THI)

Compound techniques

Transducer type (e.g., cardiac, convex, linear, microconvex probes)

Transducer shape

Transducer size (image size, width)

Transducer frequency, multi-frequency

Depth penetration (transmit zone from the transducer, from the pleura)

Focus level setting, single or multiple focuses (kind of focus, e.g., electronic)

Gain, depth gain compensation (DGC)

Dynamic range

Persistence

Tissue equalization technology

Frame rate

Line density

Smoothing parameters [depending on the equipment used, e.g., “edge” (sharper or smoother border), “delta” (to control the degree of contrast resolution within an image), space time (temporal resolution, spatial resolution)]

Other preprocessing parameters

Post processing parameters

Patient’s position, depth and circle of respiration

Area of examination

Focal changes of the pleura with or without pleural effusion

Examiner

Time of examination

Inter- and intra-observer variability

Pulmonary and extra-pulmonary disease

BLA, B-line artifact.