A mammography system includes a patient support with a breast opening. Beneath the patient support, an x-ray source transmits x-rays through a breast of a patient extending through the opening. An opposing x-ray detector receives the x-rays to obtain an x-ray image of the breast. The x-ray source and x-ray detector rotate around the opening while maintaining a fixed relation relative to one another, and a container is filled with a fluid and positioned proximate to and aligned with the opening to receive the breast. An ultrasound transmitter transmits sound waves through the breast when positioned within the fluid. An opposing ultrasound receiver receives the sound waves to obtain an ultrasound image of the breast. In a preferred embodiment, the mammography system positions the ultrasound transmitter and/or ultrasound receiver at a first position when obtaining the x-ray image of the breast and a second position when obtaining the ultrasound image of the breast. In other preferred embodiments, mammography methods correspond thereto.