Ultrasonic imaging method, wherein: a) at least one ultrasonic pulse is generated by activating a plurality of transmitting electroacoustic transducers (1, 101 to 801) of a predetermined array of transmitting transducers (1, 101 to 801), which pulse is directed into a region under examination of a body under examination; b) said transmitting transducers (1, 101 to 801) being uniformly actuated in such a manner as to generate a series of unfocused or partly focused acoustic waves; c) at a reference straight or curved line or plane or surface, the time-domain signal, consisting of the transmit pulse back-scattered from the structure of the region under examination is received by each of the receiving transducers (2, 102 to 802) of a receiving transducer array, possibly composed of the same transmitting transducers (1, 101 to 801); d) back propagation is calculated for the received signal from each receiving transducer (1, 101 to 801) to at least one straight or curved line or plane or surface (21, 22, 23, 24, 25) through which the signal penetrates the region under examination, which straight or curved line or plane or surface of penetration (21, 22, 23, 24, 25) is at a certain distance from the reference straight or curved line or plane or surface and corresponds to a predetermined penetration depth of the transmit pulse in the region under examination; e) the signals obtained by back propagation calculation, from each receiving transducer (102 to 802), are combined and processed to obtain display driving signals for reconstructing an image on a display; characterized in that a limited number of processing channels is provided, which is smaller than the number of receiving electroacoustic transducers (2, 102 to 802), and is an integer submultiple of said number of receiving transducers (2, 102 to 802), whereas for each imaging operation along a whole scan plane or a part thereof, a number of transmission steps is provided in each one of which all the transmitting transducers (1, 101 to 801) are activated, which number of transmission steps is at least equal to the total number of receiving transducers, divided by said limited number of processing channels, a different group of the receiving transducers (2, 102 to 802) of the array being connected, for each transmission step, to the processing channels, the groups of receiving transducers being composed of as many receiving transducers as the processing channels in use and in that it provides a number of processing channels greater than one, a different number of channels being selectable for processing, which number is variable from a minimum number of said processing channels, i.e. one channel, and a maximum number of said channels, i.e. all the processing channels. a) at least one ultrasonic pulse is generated by activating a plurality of transmitting electroacoustic transducers (1, 101 to 801) of a predetermined array of transmitting transducers (1, 101 to 801), which pulse is directed into a region under examination of a body under examination; b) said transmitting transducers (1, 101 to 801) being uniformly actuated in such a manner as to generate a series of unfocused or partly focused acoustic waves; c) at a reference straight or curved line or plane or surface, the time-domain signal, consisting of the transmit pulse back-scattered from the structure of the region under examination is received by each of the receiving transducers (2, 102 to 802) of a receiving transducer array, possibly composed of the same transmitting transducers (1, 101 to 801); d) back propagation is calculated for the received signal from each receiving transducer (1, 101 to 801) to at least one straight or curved line or plane or surface (21, 22, 23, 24, 25) through which the signal penetrates the region under examination, which straight or curved line or plane or surface of penetration (21, 22, 23, 24, 25) is at a certain distance from the reference straight or curved line or plane or surface and corresponds to a predetermined penetration depth of the transmit pulse in the region under examination; e) the signals obtained by back propagation calculation, from each receiving transducer (102 to 802), are combined and processed to obtain display driving signals for reconstructing an image on a display;