1. A system for ultrasound examination of a patient's breast, comprising: a scanning apparatus, comprising: (i) an ultrasonically transparent compressive membrane in a substantially taut state configured to selectively compress the patient's breast in a chestward direction, (ii) an ultrasound transducer, and (iii) an automated translation assembly coupled to the ultrasound transducer and configured to translate the ultrasound transducer across the compressive membrane as the ultrasound transducer scans the chestwardly compressed breast through the compressive membrane to acquire image data representative of a three-dimensional data volume of sonographic property values related to respective positions in the chestwardly compressed breast; a processor configured to process the image data representative of the three-dimensional data volume by combining said sonographic property values of said three-dimensional data volume through computer processing to generate therefrom two-dimensional thick-slice images representative of thick slices of the chestwardly compressed breast, wherein said respective positions in the chestwardly compressed breast are at fine spacings relative to a thickness of said thick slices such that one of said thick slices encompasses plural ones of said positions in its thickness direction, the two-dimensional thick-slice images comprising (a) a plurality of two-dimensional coronal thick-slice images, each coronal thick-slice image representing said sonographic property of the chestwardly compressed breast within a slab subvolume thereof between about 2 mm-20 mm thick substantially parallel to a coronal plane of the patient, and (b) a plurality of two-dimensional axial thick-slice images, each axial thick-slice image representing said sonographic property of the chestwardly compressed breast within a slab subvolume thereof between about 2 mm-20 mm thick substantially parallel to an axial plane of the patient; and a computerized display that displays said coronal thick-slice images and said axial thick-slice images.