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Early history of diagnostic ultrasound: the role of American radiologists.

In the late 1 940s, after World War II, a few scattered enthusiasts recognized the potential of ultrasonic energy to provide information that could be useful in medical diagnosis.The efforts of these innovators resulted in new concepts and in unique early images that motivated both the manufacturers of instruments and the clinical pioneers to begin to establish meaningful clinical applications for this new phenomenon. The early successes of these individuals created a momentum that encouraged additional users and provided a firm foothold and broadened horizons for this emerging technology. This article examines the highlights of this era as it unfolds up to the late 1960s with emphasis on the contmibutions of American radiologists. The earliest pioneers in the United States included three physicians, John Wild, a surgeon, George Ludwig, an internist, and Douglas Howry, a radiologist [1-6]. Of this group, Douglas Howry had the greatest influence on the other pioneers in radiology. In the late 1 940s he left a formal residency program at Denver Veterans Administration Hospital to devote more time to ultrasound research. Working in his basement with engineers William Rodemick Bliss and George Posakony, Howry pursued his goal of using ultrasound to produce accurate anatomic pictures of soft-tissue structures. In 1 949 Howry and coworkers used surplus radio and Air Force madam parts to build a pulse-echo ultrasonic scanner capable of making two-dimensional images. In 1950, using a 35-mm camera, Howry recorded the first cross-sectional images with ultrasound. However, since only a simple scanning motion was used, without compound sector scanning, the completeness of the anatomic image was not as great because interfaces not perpendicular to the beam could not be recorded. Subsequent instruments were able to correct this initial limitation.