Distribution statistics apodization with cross-correlation applied to medical ultrasound imaging

In medical ultrasound imaging, two aspects- improving image resolution and preserving background speckle are of great importance. Background speckle, as an intrinsic part of the image, contains clinical information, and its excessive suppression leads to the loss of diagnostic features in areas such as cysts. In this regard, this paper presents the distribution statistics apodization with cross-correlation (DSA-X) algorithm, which seeks to achieve a favorable trade-off between these two objectives. In the proposed method, the receive aperture is divided into two sub-apertures according to the 2-2 alternating pattern. Then, a high-resolution algorithm (known as the distribution correlation factor (DCF)) is used to obtain the beamformed images of each sub-aperture. Finally, a 2D energy-normalized correlation between the obtained outputs is calculated to obtain the proposed weighting coefficient and achieve the DSA-X image. The performance of the proposed method is evaluated through simulations and experimental data. Results demonstrate that DSA-X achieves resolution comparable to DCF (e.g., 0.89 mm vs. 0.84 mm full-width at half-maximum in simulation) while improving contrast and speckle preservation relative to DCF (e.g., 2.15 dB improvement of contrast-to-noise ratio for the geabr-0 dataset). Furthermore, DSA-X improves resolution relative to the minimum variance beamformer, while maintaining background speckle statistics comparable to the standard delay-and-sum beamformer. These findings confirm that DSA-X offers a favorable compromise between resolution enhancement and speckle preservation, making it a promising approach for clinical ultrasound imaging.