Ultrasound data (two-dimensional matrices of data)

A MATLAB (The MathWorks, Inc., MA, USA) script reads the RF frames that were acquired by the ultrasound scanner. The acquired RF signals were processed and converted to a two-dimensional matrix M(i,j) (i.e., “file_name.mat”) where i represents the ith line of sight of the image (x axis) and j is the index of the time samples of each line of sight (y axis). The chosen “file_name.mat” can be defined as follows: “a_b_c.mat” where a stands for the dual-mode microbubble (MB) type that was analysed (i.e., MB-plain, MBN-into15, MBN-into38, and MBN-on29); b describes the imaging technique that was applied (CPS3 or Chirp CPS3); c represents the negative peak pressure at the focus depth (230 or 320 kPa).
The ultrasound images were generated by processing the two-dimensional matrices by implementing the same functions as those used on the back end of the scanner system (i.e., envelope detection and logarithmic compression). Finally, the data can be used to calculate the contrast-to-tissue ratio (CTR), following the procedure described in the manuscript.