This image shows a 3D scan of a phantom which contains an array of 2 mm diameter anechoic spheres.
GE’s Active Matrix Array multi-row transducers (here, the M12L high-frequency linear array) create a uniformly thin image slice from the near to the far field. The thin image slice provides excellent contrast resolution and allows detection of small cysts, vessels, and other anatomic structures over a greatly extended range of the image.
For comparison, single-row transducers have a single, fixed elevation focus. The image slice which they produce is thin and provides excellent contrast resolution at the focus, but the beam diverges quickly away from the focus and the usable depth of field is limited.