1. A diagnostic ultrasound system for imaging multiple planes of target anatomy comprising: a matrix array probe configured to scan a plurality of image planes in real-time in a region of a body; a controller coupled to control scanning by the matrix array probe; an image processor, coupled to the matrix array probe, configured to produce real-time ultrasound images of image planes scanned by the matrix array probe; a display, coupled to the image processor, for displaying ultrasound images in real-time; data representing an anatomical model of the target anatomy; an image registration processor configured to register an ultrasound image with the data representing the anatomical model; image plane orientation data, derived from the anatomical model in response to registration of an ultrasound image, and coupled to the controller; wherein the matrix array probe is configured to scan a plurality of mutually different image planes in real-time, at least one of which is identified by the image plane orientation data.