1. A mammography system, comprising: a patient support having at least one opening therein; an x-ray source configured to transmit x-rays through, at least in part, a portion of at least one breast of a patient extending, at least in part, through the opening; an x-ray detector opposing the x-ray source and configured to receive the x-rays transmitted from the x-ray source to obtain, at least in part, an x-ray image of that portion of the breast; a mounting structure configured to rotate the x-ray source and x-ray detector at multiple rotational positions around the opening while the x-rays transmitted by the x-ray source impinge on the x-ray detector, and the x-ray source and x-ray detector maintain a fixed relation relative to one another; a container configured to be filled, at least in part, with a fluid and positioned proximate to and aligned with the opening to receive, at least in part, that portion of the breast; an ultrasound transmitter configured to transmit sound waves through, at least in part, that portion of the breast when positioned, at least in part, within the fluid; and an ultrasound receiver opposing the ultrasound transmitter and configured to receive the sound waves from the ultrasound transmitter to obtain, at least in part, an ultrasound image of that portion of the breast.