The first laser ultrasound performed remotely using ultrasound

This is a great first that will mark a milestone in the history of medical imaging: the first laser ultrasound performed remotely, using ultrasound.

Produced by researchers from the prestigious Massachusetts Institute of Technology (MIT), it allows, according to its authors, to obtain an image inside the organism and this, without contact with the body, and from a distance.

The same results as a conventional ultrasound

For many, ultrasound is a safe, painless and non-invasive procedure. It consists of pressing an ultrasound probe with gel on the surface of the skin to generate an image at the desired location. The probe emits sound waves into the tissue, and various features like muscle, fat, blood vessels, and bone reflect the sound back to the probe, which records the reflected signals and produces an ultrasound image. Since the probe must contact the surface of the skin to transmit and detect the ultrasound, the orientation of the probe on the surface of the skin and the compression of the skin create contact-sensitive images.

For some people such as newborns, trauma or burn victims, or surgical patients, this touch sensitivity can be very poorly tolerated. This is why this alternative approach to ultrasound developed by MIT researchers is so revolutionary.

In an article published in the journal Light Science & Applicationthey explain developed a new technique which does not require any direct contact with the surface of the skin since it is capable of remotely detecting ultrasound.

In detail, the emission laser sends out a light pulse which is quickly absorbed by the skin and converted into sound waves by the photo-acoustic effect, that is, the generation of sound by light. The sound waves generated interact with tissues identical to conventional ultrasound and the reflected signals are detected by a laser interferometer on the surface of the skin. The lasers are then moved over the surface of the skin to produce an image.

Successfully tested on human subjects, this system has shown that laser ultrasound is sensitive to the same tissue characteristics detected by conventional ultrasound. It also allows images to be obtained at centimeter depths, which is much deeper than other optical ultrasound techniques and is comparable to the imaging depths of modern clinical ultrasound.

A promising discovery

For the researchers, these first results of laser ultrasound are very encouraging. “We are at the beginning of what we could do with laser ultrasound,” explains Brian W. Anthony, principal investigator in the Department of Mechanical Engineering at MIT and the Institute for Medical Engineering and Science (IMES). “Imagine getting to a point where we can do everything ultrasound can do now, but from a distance. It gives you a whole new way to see organs inside the body and determine deep tissue properties, without coming into contact with the patient.”

Now, researchers hope to improve current technology and push laser ultrasound into future clinical use. “As related technology fields advance, one can imagine designing a laser scanning system that can take remote, volumetric images of a patient without ever disturbing them or coming into contact.”