Sonographic transducer performance cannot be evaluated with clinical images.

A wide variety of in vitro tests, some too sophisticated to perform in a clinical setting, is available to provide information on the performance of sonographic transducers. However, it is a common belief among many clinicians that clinically generated in vivo images are a necessary and sufficient test of sonographic image quality. In order to examine the sensitivity and reliability of quality judgments made from clinical images, some transducers that failed elaborate in vitro tests were used to create clinical scans. In a discrimination test between clinical images created by normal and abnormal transducers, a panel of experienced sonographers was unable to consistently identify scans made by transducers with major flaws in the beam uniformity when the defect occurred only in the near field. The study confirms that rigorous in vitro tests provide unique information on transducer performance and can reveal performance flaws that are overlooked in routine clinical images.