An adjunctive ultrasound mammography system and associated methods use an adjunctive ultrasound display configured for quick, intuitive, interactive viewing of volumetric ultrasound scans, displayed near a conventional x-ray mammogram display. Preferred navigations among a thick-slice image array, a selected enlarged thick-slice image, and planar ultrasound views are described, including a mode in which the planar ultrasound views are updated in real time as a cursor is moved across an active thick-slice image. In one example the thick-slice images are inverted prior to display, with non-breast areas of the image preferably segmented out and reset to dark. The inverted thick-slice images are of more familiar significance to radiologists as they are more like conventional x-ray mammograms and allow benign features to be more easily dismissed as compared to non-inverted thick-slice images. Preferred embodiments emphasize larger mass lesions and that compensate for mass lesions that straddle thick-slice region borders.