Influence of insonification angle on echogenicity of B-mode images of atherosclerotic plaque in vitro

A newly developed (off-line) spatial compound scanner was used to scan formalin-fixed atherosclerotic carotid plaques. Forty-eight B-mode images were recorded using 7 insonification angles. All calculations were done on the envelope-detected image data. The mean amplitude level (MAL) in (relative) volts was calculated for the plaque region in each image. The standard deviation over the 48 MAL values were for each of the 7 angles between 0.12 V and 0.18 V. For each scan plane, the standard deviation was also calculated over the 7 images. The mean and standard deviation of these 48 numbers were 0.07 V and 0.04 V, respectively. Thus based on these data, the variation from scan plane to scan plane is normally larger than the variation over angle for a single scan plane