*IF* all the images look like this, it is rather easy, EXCEPT for the fact that the bottom edge of the ultrasound is not very well defined.
The key is to find the background to determine the foreground, The background is black, so take only one channel (the image is RGB), compare against zero and that would give the background but with the annotations and bits you want to remove, so close the image with imclose with a structural element sufficiently large to cover those elements:
Then, you only need to take the complement and recover the ultrasound part
imagesc(A6__14_9N_.*(repmat(1-background,[1 1 3])))
If you compare with the original, it seems that the job is done.