reception is achieved as described above the endoscope 22 is inserted within the body with the balloon 26 39 deflated the balloon 26 39 is inflated at the desired body location to provide good surface contact and efficient transmission and reception of ultrasonic energy in an alternative embodiment the electrodes 16 39 may be on the inside surface of the balloon 26 39 it should be understood that in alternative embodiments in accordance with the invention the longitudinal strip electrodes 16 and continuous cylinder electrodes 12 ca be reversed in position that is the electrodes 16 are positioned closer to the endoscope 22 and the continuous cylindrical electrode 12 is away from the endoscope shaft 24 further the electrode 12 may also be divided into separated strips segments and the like the electrodes 12 16 may also be divided in the longitudinal direction and in patterns to suit a desired objective each electrode segment in use is connected by a lead directly or indirectly to a driving signal generating data processing system external to the human body in fig5 a sheath 30 is similar to the sheath 10 of fig1 and 2 with the addition of flexible cuffs 32 having resilience and a greater flexibility than the piezoelectric element 14 by known techniques for example double injection molding such cuffs 32 of greater resilience and elasticity than the combined core and transducing layers 12 14.