C-and D-weighted imaging: theory and simulation

Conventional ultrasound systems depict tissue backscatter; that is, the energy reflected directly back to the transmitter. While diagnostically useful, these systems fail to exploit information available in the echoes scattered in other directions (angular scatter). This paper describes a new method of angular scatter imaging. It applies the translating apertures algorithm to maintain a nearly uniform psf over a range of interrogation angles. Data from two angles is processed to form images of the constant scatter with angle and the differential scatter with angle. The authors refer to these images as c-weighted (constant) and d-weighted (difference) images. Since psf uniformity is maintained and speckle variation avoided, these images depict local angular scatter without spatial averaging. The authors present an algorithm and accompanying equations for formation of c- and d-weighted images. They present simulations showing that c- and d-weighted images may offer improved contrast in soft tissues, and that they will significantly improve the detectability of microcalcifications (MCs), important indicators of breast cancer.