Abstract: A method is provided for observing three-dimensional pulsatile activity in a volume of a subject's tissue, which includes activating an ultrasonic probes array (25) subset portion (20) having a curvature including focussing the ultrasound energy of probes (25) constituting a selected contiguous portion of the subarray in a selected portion of a selected slice of tissue (21) along a line, converting the reflected ultrasound energy to output signals and providing output data corresponding to the pulsatile activity, varying the focus of ultrasound energy along the line and repeating the converting and processing steps to thereby select additional lines within the selected slice, selecting additional subsets of the ultrasound array of probes so as to select additional slices within the volume, and performing tomographic analysis of the output data corresponding to pulsatile activity in the plurality of selected portions of tissue, so as to obtain a three dimensional image of pulsatile activity in the presele