Disclosed is an ultrasonic transducer probe for extracting tissues or body fluids from internal body organs for diagnostic purposes, in which a cannula guide slot portion is formed separately from a carrier body on which transducer elements are arranged, whereby the cannula guide slot portion may be...http://www.google.es/patents/US4289139?utm_source=gb-gplus-sharePatente US4289139 - Ultrasonic transducer probe
