The first application of diagnostic ultrasound in medicine was in the late 1930s, when Karl Dussik, an Austrian psychiatrist and neurologist, became interested in the potential use of ultrasound for brain imaging. Ultrasound was already in use at that time by mariners for underwater imaging and also by engineers for flaw detection in metals. The piezoelectric effect was already well known, having been discovered more than half a century earlier, and the concept of using a piezoelectric crystal both to transmit and receive ultrasound was described in 1917.

Dussik’s brain imaging technique was different to today’s ultrasound, in that it was based on the transmission of ultrasound waves through an object, rather than detecting waves reflected from an object. His technique, which he called hyperphonography, involved placing a transmitter on one side of the head and a receiver on the other, and using this apparatus he was able to produce images of the ventricles of the brain. Echotransmission was also the first ultrasound technique used for cardiac imaging, by the German physiologist Wolf-Dieter Keidel, in order to make measurements of the heart and thorax.

Echoreflection was first used by Inge Edler and Carl Hellmuth Hertz in Sweden. One weekend in 1953 they borrowed an industrial device, used to detect flaws in metals by the Kockum shipyard in Malmö, to conduct their work on human subjects. By a fortunate coincidence the frequency of the echo transducer happened to be one that was suitable for cardiac imaging. The image of the heart they produced was known as an A-mode scan and was thought to show the posterior wall of the left ventricle (LV). They were soon granted an ultrasound machine of their own and began to produce M-mode scans, with which they were able to examine the mitral valve and also detect atrial thrombus, myxoma, and pericardial effusion.