Following the development of gray-scale imaging, real-time scanning, Doppler examination, and high-frequency sonography, endosonography is one of the latest major breakthroughs in the history of diagnostic ultrasound. Although early attempts at inserting ultrasound transducers in natural cavities of the body can be traced back more than two decades, only in the past few years has technology allowed the development and commercialization of effective, easy-to-use endosono scopic probes. Because the transducer can be placed in direct contact with or close to lesions, high frequencies (up to 2...