Two decades of transesophageal phased array probes.

After its introduction about two decades ago, transesophageal echocardiography (TEE) has rapidly evolved into an important diagnostic feature for the cardiologist, since it offers anatomic and hemodynamic information which cannot be obtained precordially. Part of this success was due to the developments in transducer technology which resulted in smaller probes with progressively better imaging qualities. A short review of past, recent and future developments of TEE phased array probes, in particular those at the Erasmus University in Rotterdam, will be given. Furthermore, this article discusses basic parameters of the transducer dictating image quality such as centre frequency, array aperture and focusing illustrated with several simulations. The simulations show that a poor design of the transducer will limit the resolution and will give artefacts in the two-dimensional image.