<p>A catheter-based ultrasonic transducer array (2) is provided which includes a piezoelectric member (22) sandwiched between matching layers (23) and a backing member (21). A flexible stiffening element or elements is embedded in the backing member. The element (10a, 10b) is opaque to radio frequencies and integrated along the azimuthal axis of the array (2) so as to enable a user to view the element in an image of the array derived from the array (2) output and thus determine the angular position of the array (2). A flexible interconnection assembly (11) provides an electrical connection between the electrodes of the piezoelectric member (22) and external cabling. Different methods are provided for adding a surrounding protective cover (3) to the array (2).</p>
