A Brief History of Ultrasound

Patients are always commenting to me about how great this “new” technology is that we have to see inside people’s bodies in a non-invasive way. However, what most people do not realize is that Ultrasound has been used for medical imaging purposes since the 1950’s. I suppose as science is concerned, this isn’t a very long amount of time, however the research of how these high frequency sound waves could be used, started way back in the 1700’s. It is interesting to look back and see how one of the most widely used medical imaging modaliltes came about and how it has changed over the decades to become what it is today. Moreover, one can only imagine how ultrasound technology will continue to evolve.

Ultrasound was first researched in 1790 when Italian biologist Lozzaro Spallanzani researched how bats were able to maneuver without sight. He disovered that they had an internal radar that allowed them to use high frequency sound as their way of navigating.

In 1826, physiscist/engineer Jean-Daniel Colladon used an underwater bell to accurately determine the speed of sound in water.

Pierre Currie was able to find the breakthrough needed to create the first ultrasound transducer, in 1881, when he found the connection between electrical voltage and pressure on crystalline material. We still use the crystalline material lead zircinate titinate in modern day transducers.

Not only was the historical sinking of the ship Titanic turned into a blockbuster film, it also lead to the invention of the very first ultrasound transudcer.This transducer called the “hydrophone” was developed after the ship’s sinking to detect icebergs. The “hydrophone” was later used in World War I to detect submarines.

Dr. Karl Dussik, a psychiatrist, first used ultrasound for medical purposes to attempt to detect brain tumors in his patients in the 1930’s. Later, ultrasound would be used on animals to test how it traveled through soft tissue, muscles, and organs by Dr. George Ludwig in the late 1940’s.

During World War II, Professor Ian Donald became interested in radar and sonar. In the 1950’s,when a woman presented to him with inoperable stomach cancer, he used his equipment to discover that she had an ovarian cyst which was later safely removed. He was also able to detect a twin pregnancy. Prof. Donald became the father of obstetric ultrasound.

In 1953, a cardiologist named Inge Edler along with a graduate student in Nuclear Physics named Carl Hellmuth Hertz at Lund University in Sweden,were able to detect and measure heart activity using barrowed ultrasound equipment from a ship builder.

In the 1950’s and 60’s, in order to perform and ultrasound scan on a patient, the patient had to be submerged in water in order to produce an image. At that time, the transducer being used was not in direct contact with the patient. Being that there is a large difference in the speed of sound in air and the speed of sound in soft tissue, having the patient submerged in water allowed the ultrasound to penetrate the body. Douglas Howry and Joseph Holmes improved the technology of the transducer allowing it to be used in direct contact with the patient which lead to the ultrasound pictures common in today’s technology. However, a water based gel is still applied to the patient’s skin to be used as a coupling medium that allows the ultrasound beam to enter the body.

Throughout the 1970’s, 80’s, 90’s, and continuing on into the new millenium ultrasound has continued to advance with the developement of 2D gray scale imaging, doppler, color flow doppler, and 3D imaging. Not to mention the addition of using contrast agents to further improve the diagnostic quality of images. Today, ultrasound is the second most commonly used medical imaging modality. Due to the fact that most ultrasound exams are non-invasive, cost less than many other medical tests, and that it serves as a way to avoid unnecessary surgeries, there is ongoing research and new methods applied to ultrasound technology to further it’s use and accuracy.