A method for determining, in real time, the probability that target biological tissue is opposite an ultrasonic transducer, the method including: transmitting, via an ultrasonic transducer, an ultrasonic signal into biological tissue the ultrasonic transducer receiving the transmitted ultrasonic signal which has been backscattered by the biological tissue calculating at least two instantaneous parameters of the backscattered ultrasonic signal calculating a predictive value of the presence of an acoustic signature of target biological tissue, the predictive value being calculated via a statistical law using the at least two calculated instantaneous parameters estimating the probability that the target biological tissue is opposite the ultrasonic transducer, the estimation depending on the calculated predictive value and/or on at least one strength condition based on at least one of the two calculated instantaneous parameters.
