Figure 4.
Quantification of contrast on the hypoechoic cyst located at 80 mm as a function of the number of plane waves. (a–c). Expanded view of the hypoechoic region located at 80 mm (green rectangle in Fig. 3 (b) and (d)) going from one array (a) to three arrays (b) and after applying the SVD beamformer (c). The ROIs indicate the inside and outside areas selected to calculate the contrast metrics. The dynamic range is 60 dB for all images. (d) The autocorrelation of the speckle as a function of the lateral distance confirms the change in speckle aspect utilizing three arrays with reduced lateral correlation distance. (e) The contrast ratio as a function of the number of angles shows a slight degradation going from one to three arrays that is partially compensated by the SVD beamformer. (f, g) The contrast-to-noise ratio (f) and generalized contrast-to-noise ratio (g) as a function of the number of angles are very similar between one and three arrays, especially for a higher number of angles. A small degradation is seen for three arrays for a small number of angles but is compensated when applying the SVD beamformer.