A transesophageal phased array transducer for ultrasonic imaging of the heart

In this thesis the development of a miniaturized phased array ultrasound transducer is described. The application of this transducer in the field of echocardiology is devoted to transesophageal cross-sectional scanning of the heart and its great vessels. The enormous increase in diagnostic applications of ultrasound over the last three decades is particularly due to the non-invasive character of this technique. Consequently the developments of transcutaneous scanning techniques have outnumbered all other possibilities, but researchers have continuously been investigating the alternatives of scanning organs from within the human body. In those patients in whom inhibiting factors preclude adequate diagnostic information to be obtained transcutaneously, alternative scanning techniques still may-provide vital information. For cardiac imaging two possibilities exist to enter the human body, invasively by means of a catheter or 'non-invasively' by means of an endoscope. In Chapter I, the introduction, our early experiences with a catheter-mounted scanning system are described. The limited possibilities of such a system combined with the inherent technological complications, as well as the invasive character of such a technique favoured the search for a different approach. The idea to advance in the catheter direction was never left but first the experience gained has been applied to transesophageal scanning with an endoscope-mounted transducer as described in this thesis.