Method for focusing an ultrasonic wave field

Method for focusing an ultrasonic wave field in a medium (1) including a targeted ultrasonic contrast agent (3), by an array (4) of several transducers (5), said method including: (a) an emission step in which a first ultrasonic wave field is transmitted in the medium and scattered by scatterers in said medium, which transmit a scattered wave to said transducer array, (b) a capture step in which the transducers i of the transducer array capture respective scattered signals S i (t) generated ed by said scattered wave; (c) a focusing step in which each transducer i of the transducer array emits an emission signal e i (t) which is a Time reversal of a signature signal Si(t) obtained from the scattered signal S i (t) received by said transducer i, to create a focused ultrasonic wave field in the medium.