Carotid Artery Motion Estimation From Sequences of B-Mode Ultrasound Images: Effect of Scanner Settings and Image Normalization

The motion of the carotid artery wall can quantitatively be estimated from sequences of B-mode ultrasound images. In this paper, the effects of dynamic range (DR) and persistence, along with that of image normalization, were studied, in an attempt to suggest optimal values for reliable motion analysis. Image sequences were recorded using four different values for DR, i.e., 0, 48, 66, and 90 dB, and three different values for persistence, i.e., 0, 5.6, and 50. Radial and axial displacements, as well as the correlation coefficients (CCs), were estimated using block matching from recordings with durations of about 3 s. The variances of radial and axial displacements were not significantly affected by changes in DR and persistence. The mean value of the CC, which is an index of the reliability of motion analysis, was also not significantly affected by these settings. However, an increase in persistence increased the delays between peak radial displacements and cardiac systole. Image normalization did not affect the results of motion analysis. It is suggested that high values of DR (66 or 90 dB) and low values of persistence (0 or 5.6) are used for motion analysis based on block matching.