Properly accounting for ultrasound scattering from heterogeneities within the breast is essential for high-resolution ultrasound breast imaging. This requires a reflectivity image reconstruction method capable of accurately handling ultrasound scattering. We develop an optimized ultrasound-wave propagator for reflectivity image reconstruction using pulse-echo ultrasound signals. The method is based on a solution of one-way wave equation and recursive inward continuation of ultrasound wavefields in the frequency-space and frequency-wavenumber domains using a heterogeneous sound-speed model of the breast obtained from tomography. It minimizes ultrasound phase errors during wavefield inward continuation while maintaining the advantage of high computational efficiency. Pulse-echo ultrasound imaging tests for a numerical breast phantom demonstrate that our optimized method has the potential to improve the reliability and accuracy of ultrasound breast imaging.