Untracked elastography: NCC window size vs. speed and image quality.

The table shows the change in frame rate and in CNR and SNR according to NCC window size of the multi-stream elastography. We varied the window size while fixing the maximum NCC search distance at 2 mm and overlap of 98%. The CNR and SNR were averaged for 198 images. The speed was calculated by calculating elastography images for the first 100 RF pairs 20 times. It is found that window size of 10 is optimal with high mean CNR and a good mean SNR value; although the highest mean SNR value corresponds to window size 14. This table indicates that as the window size increases the mean CNR and SNR increase along with a reduction in frame rate. Intermediate frame rates corresponding to window sizes 8 and 10 give satisfactory mean CNR and SNR and a high frame rate of 52.07 and 48.16 respectively.Untracked elastography: NCC window size vs. speed and image quality.