Improved lateral resolution and contrast in ultrasound imaging using a sidelobe masking technique

In this paper, we propose a method to improve the lateral resolution and the contrast of ultrasound images, based on the cancellation of the sole contribution due to the sidelobes, thus maintaining the original depth of field and penetration capability. In the proposed method, each scan line is obtained by compounding the signals reconstructed by two emissions. For the first one, typical aperture and apodization profile are adopted. In the second emission, the same aperture is used, but the sign of the apodization profile is inverted over the second half of the aperture. The same approach is applied in receive. In this way, the second two-way beam has a main lobe with near-zero amplitude and sidelobes close to those of the first beam. The RF echo-signals corresponding to the two emissions are demodulated and successively subtracted. The resulting signal is finally log-compressed and scan converted. Simulations and in vivo experiments show a significant improvement of both detail and contrast resolution.