Ultrasound machines are not just one of the most used diagnostic tools in the world, but also one of the safest diagnostic tools. From pregnant women to gallstones, ultrasounds are the best tools for imaging the torso. Here is a brief history of how Ultrasound technology evolved.
Lazzaro Spallanzani and the Bats
As far back as the 1700s, Italian biologist, Lazzaro Spallanzani was the first to demonstrate the existence of high-frequency ultrasound. While experimenting with bats, in a dark room, he realised the bats could find their way around even when they were blinded. When he tried the same experiment with owls, the owls could not fly without some source of light. This experiment proved the presence of some other physical measure that guides the bats in their flight.
Another experiment, carried out by blocking the bats’ ears, got extremely different results. This time the bats flew into strings tired across the room and their flights were not longer co-ordinated. Spallanzani concluded that the bats relied on a sense of sound to locate barriers in their path. In 1826, Swiss Physicist, Jean-Daniel Colladon took it further by measuring the speed of sound in the water of Lake Geneva using an underwater bell.
Then came the Currie brothers with the discovery of the piezoelectric effect and materials in 1880. This was quite a breakthrough for echo-location technology. Piezoelectric materials produce an electric potential when mechanical pressure is applied to them. The materials were applied in the production of generators and receptors for the ultrasound tech.
The term Ultrasound simply refers to the sound of such a low frequency that humans can not hear it. It is quite common in nature and emitted by animals such as bats, dolphins and whales that use ultrasound for echolocation and mating calls.
Underwater SONAR (Sound Navigation and Ranging) used to measure underwater distances were used for submarine navigation during world war one. This was important particularly after the loss of the Titanic to an underwater ice-berg in 1912.
First medical application of ultrasound was as a therapy before William Fry applied it as a neurosurgical tool. Fry used it to destroy Ganglia and carry out craniotomies on certain patients. When the 1940s came around, Ultrasound technology was already being touted as a cure-all in certain quarters. It was around this same time that it was being studied as a diagnostic tool.
The Medical University of Koln, Germany presented a paper discussing the diagnostic possibilities of ultrasound and the probability of detecting tumours and abscesses with it. The researchers couldn’t prove this at the time, but Australian Neurologist, Karl Dussik got to work.
Dussik identified brain tumours and cerebral ventricles by transmitting ultrasound through the skull and measuring the outcome in a process called HYPERPHONOGRAPHY. These results were first presented in 1942 and later improved on in 1947.
While these preliminary images were rudimentary and two-dimensional, it stands to reason that if ventricles could be imaged, so could brain tumours. And with the evolution of low-intensity ultrasound, the entire inner human body. Further experimentation on these images showed that they were flawed due to reflection and attenuation in the skull. The transmission technique had to be abandoned.
Nevertheless, by the late 1940s, the idea of using Ultrasounds as diagnostic tools had gained much more recognition around the United States.
George D. Ludwig, M.D., an Internist who was interning at the Naval Medical Research Institute, in 1948 developed the A-mode ultrasound equipment to detect gallstones. After this, there was no going back.
This was how the modern Ultrasound machine has evolved into something much bigger and life-saving.