Bats! That’s right. We owe a debt a gratitude to bats because without them, we may not have ultrasound technology. In 1794, it was first discovered that bats send calls (i.e., sounds) out to the environment to locate and identify objects in their path.
Over 100 years later, this concept, called echolocation, was leveraged to develop technology that helped scientists change electrical energy into sound and then change it back again. This discovery led to the first application of the technology – the hydrophone – to detect objects at the bottom of the sea. With good old-fashioned ingenuity, scientists started on a journey to use ultrasound for medical purposes.
Over the years, ultrasound has been used for everything from physical therapy for professional soccer players to treating arthritic pain and eczema.1
How is ultrasound used in medical diagnosis?
The first area for diagnostic ultrasound was the brain. An ultrasound beam was directed through the skull to detect brain tumors. Currently, one of the most common uses of ultrasound is to monitor pregnancies. However, there are many other applications, including to help guide biopsies, to diagnose the causes of pain and to assess damage after a heart attack.
The way that this is done is quite fascinating. The ultrasound machine sends high-frequency sound waves into the body through a transducer, or probe. The sound echoes off each type of tissue differently. By measuring these echoes, it is possible to know how far the tissue or organ is from the probe, as well as its size, shape and consistency. This information is used to create visual images in two-dimensions, 3D and even in 4D.
You probably also wonder why they have to spread that sticky gel on your body before moving the probe around to get an image. Well, that gel allows the sound waves to travel from the transducer to the examined area within the body and then back again.
The frequencies used for diagnostic imaging are generally in the range of 1 to 18 MHz. We can’t hear any sound because this is a frequency that is higher than what humans can hear.1
How is ultrasound used therapeutically?
Ultrasound can also be used for therapeutic purposes. INSIGHTEC’s technology, for example, uses high-intensity focused ultrasound to treat a range of medical conditions. One of the devices sends sound waves, which safely pass through tissue and bone, to meet at a very specific spot in the brain. At this spot, the tissue is heated to temperatures high enough to cause an ablation (tiny burn) to destroy the cells being targeted. For people living with essential tremor that does not respond to medication, the Neuravive focused ultrasound treatment targets a small spot in the thalamus which is responsible for the tremor.
While sound is around us all of the time, you can’t hear the sound waves produced from ultrasound. For diagnosing disease, ultrasound gives physicians the ability to see inside the body. For therapy, ultrasound gives physicians a way to treat deep in the body. No scalpels. No incisions. The new sound of surgery – focused ultrasound.